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Sample records for reactive functionality synthesis

  1. Synthesis of reactive nucleic acid analogues and their application for the study of structure and functions of biopolymers

    NASA Astrophysics Data System (ADS)

    Kanevskii, Igor'E.; Kuznetsova, Svetlana A.

    1998-07-01

    Data on the synthesis of reactive derivatives of nucleic acid analogues and their application for the study of structure and functions of biopolymers are generalised. The main types of such analogues including photoactivated reagents containing azidoaryl, halogeno, and thiol groups, psoralen and its derivatives, platinum-based reagents, and nucleic acid analogues containing substituted pyrophosphate or acyl phosphate internucleotide groups are presented. The mechanisms of interaction of these compounds with proteins and nucleic acids are considered. The prospects for the in vivo application of reactive nucleic acids in various systems are discussed. The bibliography includes 76 references.

  2. Tailored functionalization of ZnO nanoparticle via reactive cyclodextrin and its bionanocomposite synthesis.

    PubMed

    Abdolmaleki, Amir; Mallakpour, Shadpour; Borandeh, Sedigheh

    2014-03-15

    β-cyclodextrin was grafted onto the surface of ZnO nanoparticles via efficient, simple and fast technique through nucleophilic substitution reaction of OH groups on ZnO nanoparticle surface with reactive cyclic oligosaccharide, Monochlorotriazinyl-β-cyclodextrin (MCT-β-CD). Characterization of functionalized ZnO nanoparticles were carried out by Fourier transform infrared spectra (FT-IR), elemental analysis (CHN), Thermogravimetric analysis (TGA), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The amount of MCT-β-CD bonded to the ZnO surface was determined by CHN and TGA analysis. Followed by, innovative poly(ester-amide)/ZnO bionanocomposites (PEA/ZnO BNCs) were fabricated through solution mixing method. Due to using biodegradable amino acid containing polymer, the synthesized nanocomposites are expected to classify as biologically active materials. Morphological studies of prepared BNC proved good distribution of modified ZnO in PEA matrix with nanoscale size. Good dispersion and less aggregation, indicate the effect of functionalization on preventing nanoparticles to aggregate.

  3. 2,2,6,6-Tetramethylpiperydinyl-1-oxyl (TEMPO) Functionalized Benzoxazines Prepared with a One-Pot Synthesis for Reactive/Crosslinkable Initiators of Nitroxide Mediated Polymerization.

    PubMed

    Han, Yi-Jen; Liu, Ying-Ling

    2017-08-01

    In this work, the incorporation of a 2,2,6,6-tetramethylpiperydinyl-1-oxyl (TEMPO) group to a benzoxazine ring is performed using a one-pot synthesis for the preparation of TEMPO-functionalized benzoxazine compounds and polymers as reactive and crosslinkable initiators for nitroxide-mediated polymerization (NMP). The TEMPO-functionalization reaction of benzoxazine, traced with (1) H NMR, is conducted with sequential radical transfer and coupling reactions. Moreover, polystyrene-grafted polybenzoxazine copolymers are prepared with the TEMPO-benzoxazine initiator and NMP of styrene. The polymerization system exhibits the characteristics of controlled radical polymerization, including controlled molecular weights of products and ability for sequential polymerization. Moreover, based on the chemical reactivity and crosslinking ability of benzoxazine groups, the synthesis route developed in this work will widen the scope of the design and synthesis of functional and high-performance polymers. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Metallacyclopentadienes: synthesis, structure and reactivity.

    PubMed

    Ma, Wangyang; Yu, Chao; Chen, Tianyang; Xu, Ling; Zhang, Wen-Xiong; Xi, Zhenfeng

    2017-02-20

    Metallacyclopentadienes, which possess two M-C(sp(2)) bonds and feature the structure of M(C[upper bond 1 start]R(1)[double bond, length as m-dash]CR(2)-CR(3)[double bond, length as m-dash]C[upper bond 1 end]R(4)), are an important class of five-membered metallacycles. They are considered as both reactive intermediates in the stoichiometric and catalytic transformations of organic molecules and useful precursors to main group element compounds, and have received considerable attention in organometallic chemistry, coordination chemistry and synthetic organic chemistry over the past six decades because of their unique metallacyclic structure. This review comprehensively presents the synthesis, structure and reactivity of the s-, p-, d- and f-block metallacyclopentadienes distributed in the whole periodic table. In addition, their application in synthetic organic chemistry and polymer chemistry is summarized. This review aims to be beneficial for the design and synthesis of novel metallacyclopentadienes, and for promoting the rapid development of metallacyclic chemistry.

  5. Synthesis, characterization and reactivity study of ethoxytriisothiocyanatosilane

    NASA Astrophysics Data System (ADS)

    Singh, Gurjaspreet; Promila, Saroa, Amandeep; Sharma, Geetika; Kalra, Pooja

    2017-07-01

    This paper defines the synthesis of ethoxytriisothiocyanatosilane (EtO)Si(NCS)4 and its novel silicon (IV) complexes (5-8). Silane 4 constitutes a unique class of silicon source with three reactive Si-NCS functionality. The synthesis of silicon complexes were carried out by reacting the 4 with four ligands viz. 2-hydroxy-5-methylazobenzene HL1, benzatriazoleHL2, 2-picolinic acid HL3and2-((3-methylpyridin-2-ylimino)methyl)phenol HL4. Compounds 5-8 were well characterized by1H, 13C, 29Si NMR, FT-IR, UV-Vis spectroscopy and elemental analysis. The redox properties of the complexes were investigated by electrochemical method using cyclic voltammetry.

  6. Synthesis and Photocatalytic Reactivity of Vinylsulfonium Ylides.

    PubMed

    Klose, Immo; Misale, Antonio; Maulide, Nuno

    2016-08-19

    Although sulfur ylides are textbook reagents in organic synthesis, surprisingly little variation of substituents on sulfur is usually observed. In particular, vinylsulfonium ylides have been neglected so far. Herein, we present a study on their synthesis and reactivity, including interesting behavior under photocatalytic conditions.

  7. Coinage Metal Hydrides: Synthesis, Characterization, and Reactivity.

    PubMed

    Jordan, Abraham J; Lalic, Gojko; Sadighi, Joseph P

    2016-08-10

    Hydride complexes of copper, silver, and gold encompass a broad array of structures, and their distinctive reactivity has enabled dramatic recent advances in synthesis and catalysis. This Review summarizes the synthesis, characterization, and key stoichiometric reactions of isolable or observable coinage metal hydrides. It discusses catalytic processes in which coinage metal hydrides are known or probable intermediates, and presents mechanistic studies of selected catalytic reactions. The purpose of this Review is to convey how developments in coinage metal hydride chemistry have led to new organic transformations, and how developments in catalysis have in turn inspired the synthesis of reactive new complexes.

  8. Synthesis, Characterization, and Reactivity of Functionalized Trinuclear Iron–Sulfur Clusters – A New Class of Bioinspired Hydrogenase Models

    PubMed Central

    Kaiser, Manuel; Knör, Günther

    2015-01-01

    The air- and moisture-stable iron–sulfur carbonyl clusters Fe3S2(CO)7(dppm) (1) and Fe3S2(CO)7(dppf) (2) carrying the bisphosphine ligands bis(diphenylphosphanyl)methane (dppm) and 1,1′-bis(diphenylphosphanyl)ferrocene (dppf) were prepared and fully characterized. Two alternative synthetic routes based on different thionation reactions of triiron dodecacarbonyl were tested. The molecular structures of the methylene-bridged compound 1 and the ferrocene-functionalized derivative 2 were determined by single-crystal X-ray diffraction. The catalytic reactivity of the trinuclear iron–sulfur cluster core for proton reduction in solution at low overpotential was demonstrated. These deeply colored bisphosphine-bridged sulfur-capped iron carbonyl systems are discussed as promising candidates for the development of new bioinspired model compounds of iron-based hydrogenases. PMID:26512211

  9. Synthesis, Characterization, and Reactivity of Functionalized Trinuclear Iron-Sulfur Clusters - A New Class of Bioinspired Hydrogenase Models.

    PubMed

    Kaiser, Manuel; Knör, Günther

    2015-09-01

    The air- and moisture-stable iron-sulfur carbonyl clusters Fe3S2(CO)7(dppm) (1) and Fe3S2(CO)7(dppf) (2) carrying the bisphosphine ligands bis(diphenylphosphanyl)methane (dppm) and 1,1'-bis(diphenylphosphanyl)ferrocene (dppf) were prepared and fully characterized. Two alternative synthetic routes based on different thionation reactions of triiron dodecacarbonyl were tested. The molecular structures of the methylene-bridged compound 1 and the ferrocene-functionalized derivative 2 were determined by single-crystal X-ray diffraction. The catalytic reactivity of the trinuclear iron-sulfur cluster core for proton reduction in solution at low overpotential was demonstrated. These deeply colored bisphosphine-bridged sulfur-capped iron carbonyl systems are discussed as promising candidates for the development of new bioinspired model compounds of iron-based hydrogenases.

  10. Synthesis and Reactivity of Triazaphenanthrenes

    PubMed Central

    2016-01-01

    Pyridonaphthyridines (triazaphenanthrenes) were prepared in 4 steps and in 13–52% overall yield using Negishi cross-couplings between iodopicolines and 2-chloro-pyridylzinc derivatives. After chlorination, Gabriel amination and spontaneous ring-closure, the final aromatization leading to the triazaphenanthrenes was achieved with chloranil. This heterocyclic scaffold underwent a nucleophilic addition at position 6 leading to further functionalized pyridonaphthyridines. The influence of these chemical modifications on the optical properties was studied by steady-state and time-resolved optical spectroscopy. While the thiophene-substituted heterocycles exhibited the most extended absorption, the phenyl- and furan-substituted compounds showed a stronger photoluminescence, reaching above 20% quantum yield and lifetimes of several nanoseconds. PMID:27321707

  11. Synthesis, Aqueous Reactivity, and Biological Evaluation of Carboxylic Acid Ester-Functionalized Platinum–Acridine Hybrid Anticancer Agents

    PubMed Central

    Graham, Leigh A.; Suryadi, Jimmy; West, Tiffany K.; Kucera, Gregory L.; Bierbach, Ulrich

    2012-01-01

    The synthesis of platinum–acridine hybrid agents containing carboxylic acid ester groups is described. The most active derivatives and the unmodified parent compounds showed up to 6-fold higher activity in ovarian cancer (OVCAR-3) and breast cancer (MCF-7, MDA-MB-23) cell lines than cisplatin. Inhibition of cell proliferation at nanomolar concentrations was observed in pancreatic (PANC-1) and non-small cell lung cancer cells (NSCLC, NCI-H460) of 80- and 150-fold, respectively. Introduction of the ester groups did not affect the cytotoxic properties of the hybrids, which form the same monofunctional–intercalative DNA adducts as the parent compounds, as demonstrated in a plasmid unwinding assay. In-line high-performance liquid chromatography and electrospray mass spectrometry (LC-ESMS) shows that the ester moieties undergo platinum-mediated hydrolysis in a chloride concentration-dependent manner to form carboxylate chelates. Potential applications of the chloride-sensitive ester hydrolysis as a self-immolative release mechanism for tumor-selective delivery of platinum–acridines are discussed. PMID:22871158

  12. Synthesis and reactivity of iron carbene complexes

    SciTech Connect

    McCormick, F.B.

    1980-01-01

    In an effort to more fully understand the chemistry of carbene complexes, two series of complexes, Cp(CO)/sub 2/Fe- (C(XR)YR)/sup +/ and Cp(CO) (L) Fe(C(SCH/sub 3/)/sub 2/)/sup +/ where X and Y are O, S, Se, and/or NR and L is CH/sub 3/NC, P(OPh)/sub 3/, P(OCH/sub 3/)/sub 3/, PPh/sub 3/, AsPh/sub 3/, SbPh/sub 3/, C/sub 5/H/sub 5/N, or CH/sub 3/CN, were prepared, and their reactivity towards nucleophilic reagents, especially amines was studied. The purpose was to correlate the reactivity patterns of these complexes with the electronic environment of the carbene carbon. Techniques for probing the electronic environment of the carbene carbon were IR, /sup 1/H-NMR, and /sup 13/C-MNR spectroscopy. The dissertation is composed of the following five sections: (I) synthesis of cyclopentadienyldicarbonyl(dithiocarbene) iron cations and their reactions with amines; (II) preparation of eta/sup 5/-cyclopentadienyldicarbonyltri (organo-thio) methyliron complexes and the structure of eta/sup 5/-cyclopentadienyldicarbonyltri (methylthio)-methyliron; (III) synthesis and spectroscopic study of eta/sup 5/-C/sub 5/H/sub 5/(CO)/sub 2/Fe(C(XR)YR)/sup +/ carbene complexes, where X and Y are O, S, Se, and/or NR; (IV) reactions eta/sup 5/-C/sub 5/H/sub 5/(CO)/sub 2/Fe(C(XR)YR)/sup +/ carbene complexes, where X and Y are O, S, Se, and/or NR, with amines; (V) synthesis, reactivity, and spectroscopic studies of eta/sup 5/-C/sub 5/H/sub 5/(CO) (L) Fe-(C(SCH/sub 3/)/sub 2/)/sup +/ carbene complexes. Each section has an introduction, experimental section, results and discussion section and references.

  13. Reactive plasma synthesis of nanocrystalline ceramic oxides

    NASA Astrophysics Data System (ADS)

    Sreekumar, K. P.; Vijay, M.; Thiyagarajan, T. K.; Krishnan, K.; Ananthapadmanabhan, P. V.

    2010-02-01

    Reactive plasma synthesis is an attractive route to synthesize nanocrystalline materials. A 40 kW DC non-transferred arc plasma reactor has been designed and developed in our laboratory for synthesis of nanocrystalline materials. The main components of the plasma reactor include a 40 kW DC plasma generator or plasma torch, water-cooled reactor segment, product collection facility, DC power supply, cooling-water system and exhaust gas vent. The system has been used to synthesize nano-crystalline oxides of aluminium, titanium and zirconium. Aluminium metal powder was used as the starting material to synthesize alumina. The hydrides of Ti and Zr were used as the precursor for synthesis of nanocrystalline titania and zirconia respectively. The precursor powders were injected into the thermal plasma jet and were allowed to react with oxygen injected downstream the jet. The precursor powder particles were oxidized 'in-flight' to form nano-sized powder of the respective metal, which deposited on the walls of the reactor and collector assembly. Various analytical tools were used to characterized the products.

  14. Direct Laser Synthesis of Functional Coatings

    SciTech Connect

    P. Schaaf; Michelle D. Shinn; E. Carpene; J. Kaspar

    2005-06-01

    The direct laser synthesis of functional coatings employs the irradiation of materials with short intensive laser pulses in a reactive atmosphere. The material is heated and plasma is ignited in the reactive atmosphere. This leads to an intensive interaction of the material with the reactive species and a coating is directly formed on the materials surface. By that functional coatings can be easily produced a fast way on steel, aluminium, and silicon by irradiation in nitrogen, methane, or even hydrogen. The influence of the processing parameters to the properties of the functional coatings will be presented for titanium nitride coating produced on titanium with the free electron laser.

  15. Combining reactive sputtering and rapid thermal processing for synthesis and discovery of metal oxynitrides

    SciTech Connect

    Zhou, Lan; Suram, Santosh K.; Becerra-Stasiewicz, Natalie; Mitrovic, Slobodan; Kan, Kevin; Jones, Ryan J. R.; Gregoire, John M.

    2015-05-27

    Recent efforts have demonstrated enhanced tailoring of material functionality with mixed-anion materials, yet exploratory research with mixed-anion chemistries is limited by the sensitivity of these materials to synthesis conditions. In order to synthesize a particular metal oxynitride compound by traditional reactive annealing we require specific, limited ranges of both oxygen and nitrogen chemical potentials in order to establish equilibrium between the solid-state material and a reactive atmosphere. While using Ta-O-N as an example system, we describe a combination of reactive sputter deposition and rapid thermal processing for synthesis of mixed-anion inorganic materials. Heuristic optimization of reactive gas pressures to attain a desired anion stoichiometry is discussed, and the ability of rapid thermal processing to enable amorphous to crystalline transitions without preferential anion loss is demonstrated through the controlled synthesis of nitride, oxide and oxynitride phases.

  16. Combining reactive sputtering and rapid thermal processing for synthesis and discovery of metal oxynitrides

    DOE PAGES

    Zhou, Lan; Suram, Santosh K.; Becerra-Stasiewicz, Natalie; ...

    2015-05-27

    Recent efforts have demonstrated enhanced tailoring of material functionality with mixed-anion materials, yet exploratory research with mixed-anion chemistries is limited by the sensitivity of these materials to synthesis conditions. In order to synthesize a particular metal oxynitride compound by traditional reactive annealing we require specific, limited ranges of both oxygen and nitrogen chemical potentials in order to establish equilibrium between the solid-state material and a reactive atmosphere. While using Ta-O-N as an example system, we describe a combination of reactive sputter deposition and rapid thermal processing for synthesis of mixed-anion inorganic materials. Heuristic optimization of reactive gas pressures to attainmore » a desired anion stoichiometry is discussed, and the ability of rapid thermal processing to enable amorphous to crystalline transitions without preferential anion loss is demonstrated through the controlled synthesis of nitride, oxide and oxynitride phases.« less

  17. Synthesis, crystal structure analysis, molecular docking studies and density functional theory predictions of the local reactive properties and degradation properties of a novel halochalcone

    NASA Astrophysics Data System (ADS)

    Arshad, Suhana; Pillai, Renjith Raveendran; Zainuri, Dian Alwani; Khalib, Nuridayanti Che; Razak, Ibrahim Abdul; Armaković, Stevan; Armaković, Sanja J.

    2017-09-01

    In the present study, single crystals of E)-3-(3,5-dichlorophenyl)-1-(4-fluorophenyl)prop-2-en-1-one, were prepared and structurally characterized by single crystal X-ray diffraction analysis. The molecular structure crystallized in monoclinic crystal system with P21/c space group. Sensitivity of the title molecule towards electrophilic attacks has been examined by calculations of average localized ionization energies (ALIE) and their mapping to electron density surface. Further determination of atoms that could be important reactive centres has been performed by calculations of Fukui functions. Sensitivity of title molecule towards autoxidation and hydrolysis mechanisms has been assessed by calculations of bond dissociation energies and radial distribution functions (RDF), respectively. Also, in order to explore possible binding mode of the title compound towards Dihydrofolate reductase enzyme, we have utilized in silico molecular docking to explore possible binding modes of the title compound with the DHFR enzyme.

  18. Silsesquioxane nanoparticles with reactive internal functional groups

    NASA Astrophysics Data System (ADS)

    Brozek, Eric M.; Washton, Nancy M.; Mueller, Karl T.; Zharov, Ilya

    2017-02-01

    A series of silsesquioxane nanoparticles containing reactive internal organic functionalities throughout the entire particle body have been synthesized using a surfactant-free method with organosilanes as the sole precursors and a base catalyst. The organic functional groups incorporated are vinyl, allyl, mercapto, cyanoethyl, and cyanopropyl groups. The sizes and morphologies of the particles were characterized using SEM and nitrogen adsorption, while the compositions were confirmed using TGA, FT-IR, solid state NMR, and elemental analysis. The accessibility and reactivity of the functional groups inside the particles were demonstrated by performing bromination and reduction reactions in the interior of the particles.

  19. Reactive Functionalized Membranes for Polychlorinated Biphenyl Degradation.

    PubMed

    Gui, Minghui; Ormsbee, Lindell E; Bhattacharyya, Dibakar

    2013-08-07

    Membranes have been widely used in water remediation (e.g. desalination and heavy metal removal) because of the ability to control membrane pore size and surface charge. The incorporation of nanomaterials into the membranes provides added benefits through increased reactivity with different functionality. In this study, we report the dechlorination of 2-chlorobiphenyl in the aqueous phase by a reactive membrane system. Fe/Pd bimetallic nanoparticles (NPs) were synthesized (in-situ) within polyacrylic acid (PAA) functionalized polyvinylidene fluoride (PVDF) membranes for degradation of polychlorinated biphenyls (PCBs). Biphenyl formed in the reduction was further oxidized into hydroxylated biphenyls and benzoic acid by an iron-catalyzed hydroxyl radical (OH•) reaction. The formation of magnetite on Fe surface was observed. This combined pathway (reductive/oxidative) could reduce the toxicity of PCBs effectively while eliminating the formation of chlorinated degradation byproducts. The successful manufacturing of full-scale functionalized membranes demonstrates the possibility of applying reactive membranes in practical water treatment.

  20. Design and synthesis of reactive separation systems

    SciTech Connect

    Doherty, M.F.

    1992-01-01

    During the last decade there has been a rapid upturn in interest in reactive distillation. The chemical process industry recognizes the favorable economics of carrying out reaction simultaneously with distillation for certain classes of reacting systems, and many new processes have been built based on this technology. Interest is also increasing by academics and software vendors. Systematic design methods for reactive distillation systems have only recently begun to emerge. In this report we survey the available design techniques and point out the contributions made by our group at the University of Massachusetts.

  1. Synthesis and reactivity of highly nucleophilic pyridines.

    PubMed

    De Rycke, Nicolas; Berionni, Guillaume; Couty, François; Mayr, Herbert; Goumont, Regis; David, Olivier R P

    2011-02-04

    3,4,5-Triamino-substituted pyridines are avid for electrophiles but are still willing to give them back. In these compounds three amino groups conjoin their forces into the heterocyclic nitrogen, making it a powerful Lewis base. A short and efficient synthesis is described, and the origin of its unique activity in nucleophilic organocatalysis is rationalized by kinetics and thermodynamic quantifications.

  2. Synthesis, structure and reactivity of [15]-macrodilactones.

    PubMed

    Si, Debjani; Peczuh, Mark W

    2015-06-21

    A strategy for utilizing parameters such as the ring size, planar units and the connections between them, and the location of asymmetric centers has been applied to the design and synthesis of a new class of 15-membered macrocycles. The interplay between three planar units in combination with a hinge atom and a stereogenic center, introduces a planar chirality that defines the molecular topology of these [15]-macrodilactones.

  3. Covalent functionalization of graphene with reactive intermediates.

    PubMed

    Park, Jaehyeung; Yan, Mingdi

    2013-01-15

    Graphene, a material made exclusively of sp(2) carbon atoms with its π electrons delocalized over the entire 2D network, is somewhat chemically inert. Covalent functionalization can enhance graphene's properties including opening its band gap, tuning conductivity, and improving solubility and stability. Covalent functionalization of pristine graphene typically requires reactive species that can form covalent adducts with the sp(2) carbon structures in graphene. In this Account, we describe graphene functionalization reactions using reactive intermediates of radicals, nitrenes, carbenes, and arynes. These reactive species covalently modify graphene through free radical addition, CH insertion, or cycloaddition reactions. Free radical additions are among the most common reaction, and these radicals can be generated from diazonium salts and benzoyl peroxide. Electron transfer from graphene to aryl diazonium ion or photoactivation of benzoyl peroxide yields aryl radicals that subsequently add to graphene to form covalent adducts. Nitrenes, electron-deficient species generated by thermal or photochemical activation of organic azides, can functionalize graphene very efficiently. Because perfluorophenyl nitrenes show enhanced bimolecular reactions compared with alkyl or phenyl nitrenes, perfluorophenyl azides are especially effective. Carbenes are used less frequently than nitrenes, but they undergo CH insertion and C═C cycloaddition reactions with graphene. In addition, arynes can serve as a dienophile in a Diels-Alder type reaction with graphene. Further study is needed to understand and exploit the chemistry of graphene. The generation of highly reactive intermediates in these reactions leads to side products that complicate the product composition and analysis. Fundamental questions remain about the reactivity and regioselectivity of graphene. The differences in the basal plane and the undercoordinated edges of graphene and the zigzag versus arm-chair configurations

  4. Reactivity of functionalized indoles with rare-earth metal amides. Synthesis, characterization and catalytic activity of rare-earth metal complexes incorporating indolyl ligands.

    PubMed

    Feng, Zhijun; Wei, Yun; Zhou, Shuangliu; Zhang, Guangchao; Zhu, Xiancui; Guo, Liping; Wang, Shaowu; Mu, Xiaolong

    2015-12-21

    The reactivity of several functionalized indoles 2-(RNHCH2)C8H5NH (R = C6H5 (1), (t)Bu (2), 2,6-(i)Pr2C6H3 (3)) with rare-earth metal amides is described. Reactions of 1 or 2 with [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 (RE = Eu, Yb) respectively produced the europium complexes [2-(C6H5N[double bond, length as m-dash]CH)C8H5N]2Eu[N(SiMe3)2] (4) and [2-((t)BuN[double bond, length as m-dash]CH)C8H5N]Eu[N(SiMe3)2]2 (5), and the ytterbium complex [2-((t)BuN[double bond, length as m-dash]CH)C8H5N]2Yb[N(SiMe3)2] (6), containing bidentate anionic indolyl ligands via dehydrogenation of the amine to the imine. In contrast, reactions of the more sterically bulky indole 3 with [(Me3Si)2N]3RE(μ-Cl)Li(THF)3 afforded complexes [2-(2,6-(i)Pr2C6H3NCH2)C8H5N]RE[N(SiMe3)2](THF)2 (RE = Yb (7), Y (8), Er (9), Dy (10)) with the deprotonated indolyl ligand. While reactions of 3 with yttrium and ytterbium amides in refluxing toluene respectively gave the complexes [2-(2,6-(i)Pr2C6H3N[double bond, length as m-dash]CH)C8H5N]3Y (11) and [2-(2,6-(i)Pr2C6H3N[double bond, length as m-dash]CH)C8H5N]2Yb(II)(THF)2 (12), along with transformation of the amino group to the imino group, and also with a reduction of Yb(3+) to Yb(2+) in the formation of 12. Reactions of 3 with samarium and neodymium amides provided novel dinuclear complexes {[μ-η(5):η(1):η(1)-2-(2,6-(i)Pr2C6H3NCH2)C8H5N]RE[N(SiMe3)2]}2 (RE = Sm (13), Nd (14)) having indolyl ligands in μ-η(5):η(1):η(1) hapticities. The pathway for the transformation of the amino group to the imino group is proposed on the basis of the experimental results. The new complexes displayed excellent activity in the intramolecular hydroamination of aminoalkenes.

  5. Synthesis and reactivity of tantalum corrole complexes.

    PubMed

    Ziegler, Jessica A; Buckley, Heather L; Arnold, John

    2017-01-17

    Reaction of the free base corrole (Mes2(p-OMePh)corrole)H3 with tantalum trialkyl precursors TaMe3Cl2 and TaBn3N(t)Bu resulted in the formation of the tantalum dichloride (1) and tantalum imido (4) corrole complexes via alkane elimination. The X-ray crystal structures of these two compounds have been determined and the structural parameters are discussed. The Ta centre of 1 was found to sit out of the plane of the corrole ring by 0.903 Å and is cis-ligated, similarly to what has been reported for group 4 porphyrin complexes. From complex 1 we synthesized the dimethyl derivative (2), the reactivity of which is compared to an analogous tantalum dimethyl porphyrin cation. The imido complex 4 reacted with triphenylmethanol and 4-methylbenzyl alcohol, resulting in different extents of protonation of the imido group.

  6. Reactive Functionalized Membranes for Polychlorinated Biphenyl Degradation

    PubMed Central

    Gui, Minghui; Ormsbee, Lindell E.; Bhattacharyya, Dibakar

    2014-01-01

    Membranes have been widely used in water remediation (e.g. desalination and heavy metal removal) because of the ability to control membrane pore size and surface charge. The incorporation of nanomaterials into the membranes provides added benefits through increased reactivity with different functionality. In this study, we report the dechlorination of 2-chlorobiphenyl in the aqueous phase by a reactive membrane system. Fe/Pd bimetallic nanoparticles (NPs) were synthesized (in-situ) within polyacrylic acid (PAA) functionalized polyvinylidene fluoride (PVDF) membranes for degradation of polychlorinated biphenyls (PCBs). Biphenyl formed in the reduction was further oxidized into hydroxylated biphenyls and benzoic acid by an iron-catalyzed hydroxyl radical (OH•) reaction. The formation of magnetite on Fe surface was observed. This combined pathway (reductive/oxidative) could reduce the toxicity of PCBs effectively while eliminating the formation of chlorinated degradation byproducts. The successful manufacturing of full-scale functionalized membranes demonstrates the possibility of applying reactive membranes in practical water treatment. PMID:24954974

  7. Immune Function and Reactivation of Latent Viruses

    NASA Technical Reports Server (NTRS)

    Butel, Janet S.

    1999-01-01

    A major concern associated with long-duration space flight is the possibility of infectious diseases posing an unacceptable medical risk to crew members. One major hypothesis addressed in this project is that space flight will cause alterations in the immune system that will allow latent viruses that are endogenous in the human population to reactivate and shed to higher levels than normal, which may affect the health of crew members. The second major hypothesis being examined is that the effects of space flight will alter the mucosal immune system, the first line of defense against many microbial infections, including herpesviruses, polyomaviruses, and gastroenteritis viruses, rendering crew members more susceptible to virus infections across the mucosa. We are focusing the virus studies on the human herpesviruses and polyomaviruses, important pathogens known to establish latent infections in most of the human population. Both primary infection and reactivation from latent infection with these groups of viruses (especially certain herpesviruses) can cause a variety of illnesses that result in morbidity and, occasionally, mortality. Both herpesviruses and polyomaviruses have been associated with human cancer, as well. Effective vaccines exist for only one of the eight known human herpesviruses and available antivirals are of limited use. Whereas normal individuals display minimal consequences from latent viral infections, events which alter immune function (such as immunosuppressive therapy following solid organ transplantation) are known to increase the risk of complications as a result of viral reactivations.

  8. Immune Function and Reactivation of Latent Viruses

    NASA Technical Reports Server (NTRS)

    Butel, Janet S.

    1999-01-01

    A major concern associated with long-duration space flight is the possibility of infectious diseases posing an unacceptable medical risk to crew members. One major hypothesis addressed in this project is that space flight will cause alterations in the immune system that will allow latent viruses that are endogenous in the human population to reactivate and shed to higher levels than normal, which may affect the health of crew members. The second major hypothesis being examined is that the effects of space flight will alter the mucosal immune system, the first line of defense against many microbial infections, including herpesviruses, polyomaviruses, and gastroenteritis viruses, rendering crew members more susceptible to virus infections across the mucosa. We are focusing the virus studies on the human herpesviruses and polyomaviruses, important pathogens known to establish latent infections in most of the human population. Both primary infection and reactivation from latent infection with these groups of viruses (especially certain herpesviruses) can cause a variety of illnesses that result in morbidity and, occasionally, mortality. Both herpesviruses and polyomaviruses have been associated with human cancer, as well. Effective vaccines exist for only one of the eight known human herpesviruses and available antivirals are of limited use. Whereas normal individuals display minimal consequences from latent viral infections, events which alter immune function (such as immunosuppressive therapy following solid organ transplantation) are known to increase the risk of complications as a result of viral reactivations.

  9. Reactive Functionalized Multilayer Polymers in Coextrusion Process

    NASA Astrophysics Data System (ADS)

    Lamnawar, Khalid; Maazouz, Abderrahim

    2007-04-01

    Coextrusion technologies are commonly used to produce multilayered composite sheets or films with a large range of applications. The contrast of rheological properties between layers can lead to interfacial instabilities during flow. Important theoretical and experimental advances have been made during the last decades on the stability of compatible and incompatible polymers using a mechanical approach. The present study deals with the influence of this affinity on interfacial instabilities for functionalized incompatible polymers between the neighboring layers. Polyamide (PA6)/Polyethylene-grafted (GMA) or pure PE were studied with different viscosity and elasticity ratios. We have experimentally confirmed, in this case, that the weak disturbance can be predicted by considering an interphase of non-zero thickness (corresponding to interdiffusion/reaction zone) instead of a purely geometrical interface between the two reactive layers. As a first step, rheological behavior of multilayer coextruded cast films was investigated to probe: (i) the competition between polymer/polymer interdiffusion and the interfacial reaction and (ii) the influence of the interphase. The contribution of this one effect has been studied along with the increase of the number of layers. The results show that the variation in dynamic modulus of the multilayer system reflects both diffusion and chemical reaction. Finally, and in order to quantify the contribution of the effect of the interface/interphase with a specific interfacial area, an expression was developed to take into account the interphase triggered between the neighboring layers and allowed us to estimate its thickness at a specific welding time and shear rate. As the second step, we formulate an experimental strategy to optimize the process by listing the different parameters controlling the stability of the reactive multilayer flows. The plastic films of two, three and five layers were coextruded in symmetrical and asymmetrical

  10. Synthesis of Reactive Polymers for Acrolein Capture Using AGET ATRP.

    PubMed

    Beringer, Laura T; Li, Shaohua; Gilmore, Gary; Lister, John; Averick, Saadyah

    2015-10-05

    Acrolein is a toxic metabolite of the anticancer agent cyclophosphamide (CP). Current strategies to mitigate acrolein toxicity are insufficient, and in this brief article, we report the synthesis of well-defined low molecular weight block copolymers using activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) capable of reacting with the cytotoxic small molecule acrolein. Acrolein reactivity was introduced into the block copolymers via incorporation of either (a) aminooxy or (b) sulfhydryl groups. The cytoprotective effect of the polymers was compared to sodium 2-sulfanylethanesulfonate (mesna) the current gold standard for protection from CP urotoxicity, and we found that the polymers bearing sulfhydryl moieties demonstrated superior cytoprotective activity.

  11. Synthesis, Structure and Reactivity of Molecules Attached to Electrode Surfaces.

    DTIC Science & Technology

    2014-09-26

    FAD-A1i58 621 SYNTHESIS STRUCTURE AND REACTIVITY OF MOLECULES - - BARBARA DEPT OF CHEMISTRY A T HUBBARD 18 JUL 85 UNCATACHED O ELETR-8D UR .)CLFO RN...PRINCIPAL INVESTIGATOR: Arthur T. Hubbard Professor, Department of Chemistry SUniversity of California Santa Barbara, CA 93106 (805) 961-3707 CO...3 "-627 GaL NAME OF PERFORMING ORGANIZATION b. OFFICE SYMBOL 7a. NAME OF MONITORING ORGANIZATION Department of Chemistry (,rappSi abi9 ,/C.- 6c

  12. Function through synthesis-informed design.

    PubMed

    Wender, Paul A; Quiroz, Ryan V; Stevens, Matthew C

    2015-03-17

    In 1996, a snapshot of the field of synthesis was provided by many of its thought leaders in a Chemical Reviews thematic issue on "Frontiers in Organic Synthesis". This Accounts of Chemical Research thematic issue on "Synthesis, Design, and Molecular Function" is intended to provide further perspective now from well into the 21st century. Much has happened in the past few decades. The targets, methods, strategies, reagents, procedures, goals, funding, practices, and practitioners of synthesis have changed, some in dramatic ways as documented in impressive contributions to this issue. However, a constant for most synthesis studies continues to be the goal of achieving function with synthetic economy. Whether in the form of new catalysts, reagents, therapeutic leads, diagnostics, drug delivery systems, imaging agents, sensors, materials, energy generation and storage systems, bioremediation strategies, or molecules that challenge old theories or test new ones, the function of a target has been and continues to be a major and compelling justification for its synthesis. While the targets of synthesis have historically been heavily represented by natural products, increasingly design, often inspired by natural structures, is providing a new source of target structures exhibiting new or natural functions and new or natural synthetic challenges. Complementing isolation and screening approaches to new target identification, design enables one to create targets de novo with an emphasis on sought-after function and synthetic innovation with step-economy. Design provides choice. It allows one to determine how close a synthesis will come to the ideal synthesis and how close a structure will come to the ideal function. In this Account, we address studies in our laboratory on function-oriented synthesis (FOS), a strategy to achieve function by design and with synthetic economy. By starting with function rather than structure, FOS places an initial emphasis on target design

  13. Mechanochemical synthesis and reactivity of PbS nanocrystals

    NASA Astrophysics Data System (ADS)

    Baláž, Peter; Pourghahramani, Parviz; Achimovičová, Marcela; Dutková, Erika; Kováč, Jaroslav; Šatka, Alexander; Jiang, Jiangzhong

    2011-10-01

    PbS nanocrystals using surfactant assisted mechanochemical synthesis have been prepared by co-milling of lead acetate (CH 3COO) 2Pb rad 3H 2O and sodium sulfide Na 2S rad 9H 2O. The methods of XRD, FE-SEM, TEM (HRTEM), UV-vis, specific surface area measurements as well as reactivity in acidic FeCl 3 media were used for the nanocrystals characterization. The XRD patterns confirmed the presence of galena PbS (JCPDS 5-592) whatever treatment conditions were applied. The strong observable peaks indicate the highly crystalline nature in formation of PbS nanostructures where preferential crystal growth in the (2 0 0) direction after addition of ethylenediamine (EDA), sodiumdodecylsulphate (SDS) and ethylendiaminetetraacetic disodium salt dihydrate (EDH) surfactants has been observed. The surface weighted crystallite sizes 3, 8, 11 and 19 nm have been calculated from XRD data using the Warren-Averbach method for surfactant-free and/or EDA, SDS and EDH surfactants assisted mechanochemical synthesis. The leaching rate of galena PbS in acidic FeCl 3 solution has been studied. The dependence of PbS nanocrystals reactivity on preferential growth parameter is documented. The highest value of the specific rate constant of leaching, k0/ SA has been obtained for the mechanochemically synthesized PbS in presence of EDH surfactant.

  14. Lung function and bronchial reactivity in farmers.

    PubMed Central

    Iversen, M; Dahl, R; Jensen, E J; Korsgaard, J; Hallas, T

    1989-01-01

    The purpose of this study was to evaluate the prevalence and type of lung function disorders in Danish farmers. Three samples of farmers were drawn from a group of unselected farmers who had participated in an epidemiological study. Group I (47 persons) was a sample of the 8% of all farmers who had reported that they had asthma; group II (63 persons) was a sample of the 28% of farmers who had had wheezing, shortness of breath, or cough without phlegm; and group III (34 persons) a sample of the farmers (64% of the total) who had no asthma and no respiratory symptoms. The farmers with symptoms (groups I and II) had low mean levels of FEV1 and high values for residual volume, whereas the symptomless farmers had normal lung function and no airways obstruction. The proportion of farmers with an FEV1 below the 95% confidence limit for predicted values was 43% in group I and 23% in group II; there were none in group III. Bronchial hyperreactivity to histamine occurred in 96% of asthmatic farmers, 67% of farmers with wheezing or shortness of breath, and 59% of symptomless farmers. A low level of FEV1 was associated with the number of years in pig farming and bronchial hyperreactivity in group II but not group I or III. Most of the bronchial hyperreactivity was explained in the multiple regression analysis by a low FEV1, though this was significant only for farmers in group II. Thus farmers who reported asthma, wheezing, shortness of breath, or a dry cough in general had airways obstruction with an increased residual volume, whereas symptomless farmers had normal lung function. Severe bronchial hyperreactivity was mostly explained by a diagnosis of asthma and poor lung function, though some farmers with normal lung function and no respiratory symptoms had increased bronchial reactivity. PMID:2799744

  15. Function through Synthesis-Informed Design

    PubMed Central

    2016-01-01

    Conspectus In 1996, a snapshot of the field of synthesis was provided by many of its thought leaders in a Chemical Reviews thematic issue on “Frontiers in Organic Synthesis”. This Accounts of Chemical Research thematic issue on “Synthesis, Design, and Molecular Function” is intended to provide further perspective now from well into the 21st century. Much has happened in the past few decades. The targets, methods, strategies, reagents, procedures, goals, funding, practices, and practitioners of synthesis have changed, some in dramatic ways as documented in impressive contributions to this issue. However, a constant for most synthesis studies continues to be the goal of achieving function with synthetic economy. Whether in the form of new catalysts, reagents, therapeutic leads, diagnostics, drug delivery systems, imaging agents, sensors, materials, energy generation and storage systems, bioremediation strategies, or molecules that challenge old theories or test new ones, the function of a target has been and continues to be a major and compelling justification for its synthesis. While the targets of synthesis have historically been heavily represented by natural products, increasingly design, often inspired by natural structures, is providing a new source of target structures exhibiting new or natural functions and new or natural synthetic challenges. Complementing isolation and screening approaches to new target identification, design enables one to create targets de novo with an emphasis on sought-after function and synthetic innovation with step-economy. Design provides choice. It allows one to determine how close a synthesis will come to the ideal synthesis and how close a structure will come to the ideal function. In this Account, we address studies in our laboratory on function-oriented synthesis (FOS), a strategy to achieve function by design and with synthetic economy. By starting with function rather than structure, FOS places an initial emphasis on

  16. Synthesis and processing of composites by reactive metal penetration

    SciTech Connect

    Loehman, R.E.; Ewsuk, K.G.; Tomsia, A.P.; Fahrenholtz, W.G.

    1996-07-01

    Ceramic-metal composites are being developed as engineering materials because of their high stiffness-to-weight ratios, good fracture toughness, and because their electrical and thermal properties can be varied through control of their compositions and microstructures. Wider use of ceramic-metal composites requires improvements in synthesis and processing so that high-performance parts can be produced more economically. Over the past three years reactive metal penetration has been shown to be a promising technique for making ceramic and metal-matrix composites to near-net-shape with control of both composition and microstructure. It appears that reactive metal penetration could be an economical process for manufacturing many of the advanced ceramic composites that are needed for light-weight structural and wear applications for transportation and energy conversion devices. Near-net-shape fabrication of parts has the additional advantage that costly and energy intensive grinding and machining operations are significantly reduced, and the waste generated from such finishing operations is minimized. The goals of this research and development program are: (1) to identify compositions favorable for making composites by reactive metal penetration; (2) to understand the mechanism(s) by which these composites are formed; and (3) to control and optimize the process so that composites and composite coatings can be made economically.

  17. Process Improvement of Reactive Dye Synthesis Using Six Sigma Concept

    NASA Astrophysics Data System (ADS)

    Suwanich, Thanapat; Chutima, Parames

    2017-06-01

    This research focuses on the problem occurred in the reactive dye synthesis process of a global manufacturer in Thailand which producing various chemicals for reactive dye products to supply global industries such as chemicals, textiles and garments. The product named “Reactive Blue Base” is selected in this study because it has highest demand and the current chemical yield shows a high variation, i.e. yield variation of 90.4% - 99.1% (S.D. = 2.405 and Cpk = -0.08) and average yield is 94.5% (lower than the 95% standard set by the company). The Six Sigma concept is applied aiming at increasing yield and reducing variation of this process. This approach is suitable since it provides a systematic guideline with five improvement phases (DMAIC) to effectively tackle the problem and find the appropriate parameter settings of the process. Under the new parameter settings, the process yield variation is reduced to range between 96.5% - 98.5% (S.D. = 0.525 and Cpk = 1.83) and the average yield is increased to 97.5% (higher than the 95% standard set by the company).

  18. Reactive Oxygen Species and Neutrophil Function.

    PubMed

    Winterbourn, Christine C; Kettle, Anthony J; Hampton, Mark B

    2016-06-02

    Neutrophils are essential for killing bacteria and other microorganisms, and they also have a significant role in regulating the inflammatory response. Stimulated neutrophils activate their NADPH oxidase (NOX2) to generate large amounts of superoxide, which acts as a precursor of hydrogen peroxide and other reactive oxygen species that are generated by their heme enzyme myeloperoxidase. When neutrophils engulf bacteria they enclose them in small vesicles (phagosomes) into which superoxide is released by activated NOX2 on the internalized neutrophil membrane. The superoxide dismutates to hydrogen peroxide, which is used by myeloperoxidase to generate other oxidants, including the highly microbicidal species hypochlorous acid. NOX activation occurs at other sites in the cell, where it is considered to have a regulatory function. Neutrophils also release oxidants, which can modify extracellular targets and affect the function of neighboring cells. We discuss the identity and chemical properties of the specific oxidants produced by neutrophils in different situations, and what is known about oxidative mechanisms of microbial killing, inflammatory tissue damage, and signaling.

  19. Carbasugars: Synthesis and Functions

    NASA Astrophysics Data System (ADS)

    Kobayashi, Yoshiyuki

    It is well recognized that glycosidase inhibitors are not only tools to elucidate the mechanism of a living system manipulated by glycoconjugates but also potential clinical drugs and insecticides by inducing the failure of glycoconjugates to perform their function. In this chapter, the syntheses and functions of natural glycosidase inhibitors (cyclophelitol , allosamidine , and trehazoilin ), which possess highly oxygenated and functionalized cyclohexanes or cyclopentanes in their structures and are defined as carbasugars , and the structure and activity relationships (SAR) of their derivatives are described. Also, recently much attention has been focused on neuraminidase inhibitors as anti-influenza drugs since relenza , which was derived from sialic acid, and also, tamiflu , which is the artificial carbasugar designed as a transition state analogue in the hydrolysis pathway of substrates by neuraminidase, were launched in the market. Herein, the medicinal chemistry efforts to discover tamiflu and some efficient syntheses applicable to process chemistry are described. Finally, useful synthetic methodologies for carbasugar formation from sugars are also introduced in this chapter.

  20. Reactivation of hepatic EPO synthesis in mice after PHD loss.

    PubMed

    Minamishima, Yoji Andrew; Kaelin, William G

    2010-07-23

    The kidney controls erythropoietin production in adults, and the anemia that can accompany renal failure is a major medical problem. The liver controls erythropoietin production during fetal life but is silenced shortly after birth. Erythropoietin transcription is controlled by hypoxia-inducible factor (HIF), which is inhibited by three prolyl hydroxylases (PHD1, PHD2, and PHD3). Systemic PHD2 inactivation has been found to increase renal, but not hepatic, erythropoietin production. In contrast, we show here that simultaneous genetic inactivation of all three PHD paralogs in mice reactivates hepatic erythropoietin production and stimulates red blood synthesis, suggesting that pan-PHD inhibitory drugs might be useful for the treatment of anemia caused by chronic kidney disease.

  1. Combustion synthesis of reactive nickel-aluminum particles as an innovative approach for thermal joining applications

    NASA Astrophysics Data System (ADS)

    Schreiber, S.; Theodossiadis, G. D.; Zaeh, M. F.

    2017-03-01

    Reactive systems, which are widely used in combustion synthesis, represent a promising solution for challenging joining tasks. They are able to undergo a self-sustaining, highly exothermic reaction when exposed to an external energy source. Reactive foils are the only systems that are currently commercially available. However, their industrial use is limited due to the brittle nature of the material and the restriction to planar geometries. Reactive particles represent a more flexible format, but are currently not commercially available. Therefore, a two-step electroless plating process has been developed to synthesize nickel-aluminum core-shell structures. These structures function as microreactors, which provide the energy for the thermal joining process. Ignition tests with electromagnetic waves were performed in order to investigate the overall reactivity. Energy input and particle size significantly influence the activation and the reaction behavior of the core-shell structures. Furthermore, a general approach to use reactive particles as a heat source in joining applications is proposed.

  2. Concise Synthesis of Functionalized Benzocyclobutenones

    PubMed Central

    Chen, Peng-hao; Savage, Nikolas A.; Dong, Guangbin

    2014-01-01

    A concise approach to access functionalized benzocyclobutenones from 3-halophenol derivatives is described. This modified synthesis employs a [2+2] cycloaddition between benzynes generated from dehydrohalogenation of aryl halides using LiTMP and acetaldehyde enolate generated from n-BuLi and THF, followed by oxidation of the benzocyclobutenol intermediates to provide benzocyclobutenones. The [2+2] reaction can be run on a 10-gram scale with an increased yield. A number of functional groups including alkenes and alkynes are tolerated. Coupling of benzynes with ketene silyl acetals to give 8-substituted benzocyclobutenones is also demonstrated. PMID:24926108

  3. Reactivity indicators for degenerate states in the density-functional theoretic chemical reactivity theory.

    PubMed

    Cárdenas, Carlos; Ayers, Paul W; Cedillo, Andrés

    2011-05-07

    Density-functional-theory-based chemical reactivity indicators are formulated for degenerate and near-degenerate ground states. For degenerate states, the functional derivatives of the energy with respect to the external potential do not exist, and must be replaced by the weaker concept of functional variation. The resultant reactivity indicators depend on the specific perturbation. Because it is sometimes impractical to compute reactivity indicators for a specific perturbation, we consider two special cases: point-charge perturbations and Dirac delta function perturbations. The Dirac delta function perturbations provide upper bounds on the chemical reactivity. Reactivity indicators using the common used "average of degenerate states approximation" for degenerate states provide a lower bound on the chemical reactivity. Unfortunately, this lower bound is often extremely weak. Approximate formulas for the reactivity indicators within the frontier-molecular-orbital approximation and special cases (two or three degenerate spatial orbitals) are presented in the supplementary material. One remarkable feature that arises in the frontier molecular orbital approximation, and presumably also in the exact theory, is that removing electrons sometimes causes the electron density to increase at the location of a negative (attractive) Dirac delta function perturbation. That is, the energetic response to a reduction in the external potential can increase even when the number of electrons decreases.

  4. Unified Synthesis of 10-Oxygenated Lycopodium Alkaloids: Impact of C10-Stereochemistry on Reactivity.

    PubMed

    Saha, Mrinmoy; Li, Xin; Collett, Nathan D; Carter, Rich G

    2016-07-15

    The pronounced impact of the C10 stereochemistry on the successful construction of a polycyclic Lycopodium alkaloid scaffold has been explored. A wide range of reaction conditions and functionality were investigated to control a keto sulfone Michael addition to construct the C7-C12 linkage. An unexpected, overriding impact of the C10 stereochemistry in stereoselectivity and reaction rate in the Michael addition was observed. Furthermore, divergent reactivity of a conformationally accelerated, intramolecular Mannich cyclization based on the C10 stereochemistry was discovered. The successful execution of this synthetic route resulted in the total synthesis of all three known 10-oxygenated Lycopodium alkaloids: 10-hydroxylycopodine, paniculine, and deacetylpaniculine.

  5. Chemical reactivity of quinmerac herbicide through the Fukui function.

    PubMed

    Mendoza-Huizar, Luis Humberto

    2014-01-01

    In the present work we have calculated DFT reactivity descriptors for quinmerac (7-chloro-3-methylquinoline-8-carboxylic acid) at the MP2/6-311++G(d,p)//B3LYP/6-311++G(2d,2p) level of theory to analyze its reactivity. Reactivity descriptors such as ionization energy, molecular hardness, electrophilicity, condensed Fukui function and total energies were calculated to predict changes in its reactivity. The Fukui function values predict that electrophilic and free radical attacks on quinmerac might cause aromatic substitutions, while nucleophilic attacks would cause cleavage of the C=N bond.

  6. Negishi Cross-Coupling Is Compatible with a Reactive B–Cl Bond: Development of a Versatile Late-Stage Functionalization of 1,2-Azaborines and Its Application to the Synthesis of New BN Isosteres of Naphthalene and Indenyl

    PubMed Central

    Brown, Alec N.; Li, Bo; Liu, Shih-Yuan

    2016-01-01

    The compatibility of the Negishi cross-coupling reaction with the versatile B–Cl functionality has been demonstrated in the context of late-stage functionalization of 1,2-azaborines. Alkyl-, aryl-, and alkenylzinc reagents have been utilized for the functionalization of the triply orthogonal precursor 3-bromo-1-(tert-butyldimethylsilyl)-2-chloro-1,2-dihydro-1,2-azaborine (2) to furnish new 2,3-substituted monocyclic 1,2-azaborines. This methodology has enabled the synthesis of previously elusive BN-naphthalene and BN-indenyl structures from a common intermediate. PMID:26148959

  7. Phthalides: Distribution in Nature, Chemical Reactivity, Synthesis, and Biological Activity.

    PubMed

    León, Alejandra; Del-Ángel, Mayela; Ávila, José Luis; Delgado, Guillermo

    2017-01-01

    oxidation, reduction, addition, elimination, and cycloaddition reactions, and treatments with Lewis acids of (Z)-ligustilide have afforded linear dimers. Some intramolecular condensations and differentiated cyclizations of the dimeric phthalides have been carried out, providing evidences for the particular chemical reactivity of these compounds.Several structural modifications of phthalides have been carried out subjecting them to microbial transformations by different species of bacteria, fungi and algae, and these included resolutions of racemic mixtures and oxidations, among others.The [π4s + π2s] and [π2s + π2s] cycloadditions of (Z)-ligustilide for the synthesis of dimeric phthalides have been reported, and different approaches involving cyclizations, Alder-Rickert reactions, Sharpless asymmetric hydroxylations, or Grignard additions have been used for the synthesis of monomeric phthalides. The use of phthalides as building blocks for divergent oriented synthesis has been proven.Many of the naturally occurring phthalides display different biological activities including antibacterial, antifungal, insecticidal, cytotoxic, and anti-inflammatory effects, among many others, with a considerable recent research on the topic. In the case of compounds isolated from the Apiaceae, the bioactivities correlate with the traditional medicinal uses of the natural sources. Some monomeric phthalides have shown their ability to attenuate certain neurological diseases, including stroke, Alzheimer's and Parkinson's diseases.The present contribution covers the distribution of phthalides in nature and the findings in the structural diversity, chemical reactivity, biotransformations, syntheses, and bioactivity of natural and semisynthetic phthalides.

  8. Synthesis, Characterization and Reactivity of a Hexane-Soluble Silver Salt

    ERIC Educational Resources Information Center

    Stockland, Robert A. Jr.; Wilson, Brian D.; Goodman, Caton C.; Giese, Barret J.; Shrimp, Frederick L., II

    2007-01-01

    The connectivity of a hexane-soluble silver salt is established by using NMR spectroscopy to describe the synthesis, characterization and reactivity of the salt. The results found hexane-soluble silver to be an effective transfer agent.

  9. Synthesis, Characterization and Reactivity of a Hexane-Soluble Silver Salt

    ERIC Educational Resources Information Center

    Stockland, Robert A. Jr.; Wilson, Brian D.; Goodman, Caton C.; Giese, Barret J.; Shrimp, Frederick L., II

    2007-01-01

    The connectivity of a hexane-soluble silver salt is established by using NMR spectroscopy to describe the synthesis, characterization and reactivity of the salt. The results found hexane-soluble silver to be an effective transfer agent.

  10. Synthesis, characterization, and reactivity of pentamethylcyclopentadienyl complexes of divalent cobalt and nickel

    SciTech Connect

    Smith, Michael Edward

    1993-10-01

    The thesis is divided into the following 4 chapters: synthesis, characterization, and reactivity of trinuclear pentamethylcyclopentadienyl cobalt and nickel clusters with triply-bridging methylidyne groups; chemical and physical properties of pentamethylcyclopentadienyl acetylacetonate complexes of Co(II) and Ni(II); synthesis, characterization, and reactivity of pentamethylcyclopentadienyl halide complexes of Co and Ni; and crystallographic studies of distortions in metallocenes with C5-symmetrical cyclopentadienyl rings.

  11. Fluorescent silica nanoparticles with chemically reactive surface: Controlling spatial distribution in one-step synthesis.

    PubMed

    Vera, María L; Cánneva, Antonela; Huck-Iriart, Cristián; Requejo, Felix G; Gonzalez, Mónica C; Dell'Arciprete, María L; Calvo, Alejandra

    2017-06-15

    The encapsulation of fluorescent dyes inside silica nanoparticles is advantageous to improve their quality as probes. Inside the particle, the fluorophore is protected from the external conditions and its main emission parameters remains unchanged even in the presence of quenchers. On the other hand, the amine-functionalized nanoparticle surface enables a wide range of applications, as amino groups could be easily linked with different biomolecules for targeting purposes. This kind of nanoparticle is regularly synthesized by methods that employ templates, additional nanoparticle formation or multiple pathway process. However, a one-step synthesis will be an efficient approach in this sort of bifunctional hybrid nanoparticles. A co-condensation sol-gel synthesis of hybrid fluorescent silica nanoparticle where developed. The chemical and morphological characterization of the particles where investigated by DRIFTS, XPS, SEM and SAXS. The nanoparticle fluorescent properties were also assessed by excitation-emission matrices and time resolved experiments. We have developed a one-pot synthesis method that enables the simultaneous incorporation of functionalities, the fluorescent molecule and the amino group, by controlling co-condensation process. An exhaustive characterization allows the definition of the spatial distribution of the fluorescent probe, fluorescein isothiocyanate, inside the particle and reactive amino groups on the surface of the nanoparticle with diameter about 100nm.

  12. Reactivity of End-functionalized Polymers Containing Diels-Alder Functional Groups

    NASA Astrophysics Data System (ADS)

    Meng, Yuan; Zhang, Yuan; Anthamatten, Mitchell

    2013-03-01

    Incorporation of reversible covalent bond into macromolecular systems has proven useful in engineering novel responsive architectures, and Diels-Alder bonding in this context is now well established. However, efficient synthesis of end-functionalized polymers is a major obstacle hindering further development of responsive and modular polymer architectures. In this current research, two immiscible polymers, poly(methyl methacrylate) (PMMA) and poly(benzyl methacrylate) (PBzMA) with controlled molecular weight, bearing terminal furan-maleimide groups, are prepared via Reversible Addition-Fragmentation chain transfer (RAFT) polymerization. The reactivity of such end-functionalized polymers is explored to expose the relationship between chain composition and their ability to undergo modular cross-coupling to form monodisperse block copolymers. To elucidate how reaction conditions affect the efficiency of the Diels-Alder reaction, Hydrogen Nuclear Magnetic Resonance (H-NMR) and Size Exclusion Chromatography (SEC) techniques are actively applied. Experimental results will be interpreted on the basis of dissimilarity between interaction energies of polymer segments and the concentration of reactive groups.

  13. Perfluorophenyl Azides: New Applications in Surface Functionalization and Nanomaterial Synthesis

    PubMed Central

    Liu, Li-Hong; Yan, Mingdi

    2010-01-01

    Conspectus A major challenge in materials science is the ongoing search for coupling agents that are readily synthesized, capable of versatile chemistry, able to easily functionalize materials and surfaces, and efficient in covalently linking organic and inorganic entities. A decade ago, we began a research program investigating perfluorophenylazides (PFPAs) as the coupling agents in surface functionalization and nanomaterial synthesis. The p-substituted PFPAs are attractive heterobifunctional coupling agents because of their two distinct and synthetically distinguishable reactive centers: (i) the fluorinated phenylazide, which is capable of forming stable covalent adducts, and (ii) the functional group R, which can be tailored through synthesis. Two approaches have been undertaken for material synthesis and surface functionalization. The first method involves synthesizing PFPA bearing the first molecule or material with a functional linker R, and then attaching the resulting PFPA to the second material by activating the azido group. In the second approach, the material surface is first functionalized with PFPA via functional center R, and coupling of the second molecule or material is achieved with the surface azido groups. In this Account, we review the design and protocols of the two approaches, providing examples in which PFPA derivatives were successfully used in material surface functionalization, ligand conjugation, and the synthesis of hybrid nanomaterials. The methods developed have proved to be general and versatile, and they are applicable to a wide range of materials (especially those that lack reactive functional groups or are difficult to derivatize) and to various substrates of polymers, oxides, carbon materials, and metal films. The coupling chemistry can be initiated by light, heat, and electrons. Patterned structures can be generated by selectively activating the areas of interest. Furthermore, the process is easy to perform, and light activation

  14. Quantitative reactivity profiling predicts functional cysteines in proteomes

    PubMed Central

    Weerapana, Eranthie; Wang, Chu; Simon, Gabriel M.; Richter, Florian; Khare, Sagar; Dillon, Myles B.D.; Bachovchin, Daniel A.; Mowen, Kerri; Baker, David; Cravatt, Benjamin F.

    2010-01-01

    Cysteine is the most intrinsically nucleophilic amino acid in proteins, where its reactivity is tuned to perform diverse biochemical functions. The absence of a consensus sequence that defines functional cysteines in proteins has hindered their discovery and characterization. Here, we describe a proteomics method to quantitatively profile the intrinsic reactivity of cysteine residues en masse directly in native biological systems. Hyperreactivity was a rare feature among cysteines and found to specify a wide range of activities, including nucleophilic and reductive catalysis and sites of oxidative modification. Hyperreactive cysteines were identified in several proteins of uncharacterized function, including a residue conserved across eukaryotic phylogeny that we show is required for yeast viability and involved in iron-sulfur protein biogenesis. Finally, we demonstrate that quantitative reactivity profiling can also form the basis for screening and functional assignment of cysteines in computationally designed proteins, where it discriminated catalytically active from inactive cysteine hydrolase designs. PMID:21085121

  15. Three bilindione isomers: synthesis, characterization and reactivity of biliverdin analogs.

    PubMed

    Wang, Jun-Fei; Ma, Fang; Sun, Hao-Ling; Zhang, Jing; Zhang, Jun-Long

    2017-02-07

    Linear tetrapyrrole is the core structure of light-sensitive native cofactors such as phycocyanobilin, phytochromobilin and bile pigments, which attracts increasing attention in biomimetic chemistry, photochemistry and coordination chemistry. To decipher the relationship between structures and functions, in this work, we firstly reported the synthesis, isolation and characterization of three bilindione isomers (ZZZ, syn, syn, syn 1, EZE, syn, syn, anti 2 and EZE, anti, syn, anti 3) bearing meso-pentafluorophenyl groups. The structures were confirmed by X-ray diffraction and 2-D NMR spectroscopes. More importantly, the interconversion between three isomers under heating and light irradiation was investigated, and isomer 3 was found to be transformed to 1 and 2 more easily, which is in line with the results of DFT calculation. This work provides important insights for understanding the relationship between structures and functions and would be important to further construct metal complexes based on linear tetrapyrrole ligands, which are complementary to well-studied the cyclic analogs such as porphyrin and corroles.

  16. Asymmetric synthesis of pyrazoles and pyrazolones employing the reactivity of pyrazolin-5-one derivatives.

    PubMed

    Chauhan, Pankaj; Mahajan, Suruchi; Enders, Dieter

    2015-08-21

    Due to the frequent occurrence of the pyrazole core in many important naturally occurring and synthetic molecules, tremendous efforts have been made for their synthesis. The pyrazolin-5-one derivatives have emerged as the most effective substrates for the synthesis of useful pyrazoles and their corresponding pyrazolone derivatives. Recently, the reactivity of pyrazolin-5-ones has been used for the asymmetric synthesis of highly functionalised pyrazole and pyrazolone derivatives by employing organo- and metal-catalysts. This feature article focuses on the progress in the catalytic asymmetric synthesis of pyrazoles and pyrazolones using pyrazolin-5-one derivatives.

  17. Relations among several nuclear and electronic density functional reactivity indexes

    NASA Astrophysics Data System (ADS)

    Torrent-Sucarrat, Miquel; Luis, Josep M.; Duran, Miquel; Toro-Labbé, Alejandro; Solà, Miquel

    2003-11-01

    An expansion of the energy functional in terms of the total number of electrons and the normal coordinates within the canonical ensemble is presented. A comparison of this expansion with the expansion of the energy in terms of the total number of electrons and the external potential leads to new relations among common density functional reactivity descriptors. The formulas obtained provide explicit links between important quantities related to the chemical reactivity of a system. In particular, the relation between the nuclear and the electronic Fukui functions is recovered. The connection between the derivatives of the electronic energy and the nuclear repulsion energy with respect to the external potential offers a proof for the "Quantum Chemical le Chatelier Principle." Finally, the nuclear linear response function is defined and the relation of this function with the electronic linear response function is given.

  18. Chemical reactivity in the framework of pair density functional theories.

    PubMed

    Otero, Nicolás; Mandado, Marcos

    2012-05-15

    Chemical reactivity descriptors are derived within the framework of the pair density functional theory. These indices provide valuable information about bonding rearrangements and activating mechanisms upon electrophilic or nucleophilic reactions. Indices derived and tested in this work represent nonlocal counterparts of the local reactivity indices derived in the context of conceptual density functional theory (CDFT) and frequently used in reactivity studies; the Fukui function, the local softness and the dual descriptor. In this work, we show how these nonlocal indices provide a quantum chemical basis to explain the success of qualitative resonance models in chemical reactivity predictions. Also, local information is implicitly contained as CDFT indices are obtained by simple integration. As illustrative examples, we have considered in this work the Markovnikov's rule, the reactivity of enolate anion, the nucleophilic conjugate addition to α,β-unsaturated compounds and the electrophilic aromatic substitution of benzene derivatives. The densities used in this work were obtained with Hartree-Fock, Kohn-Sham DFT, and singles and doubles configuration interaction (CISD) approaches.

  19. Reactive Attachment Disorder: Implications for School Readiness and School Functioning

    ERIC Educational Resources Information Center

    Schwartz, Eric; Davis, Andrew S.

    2006-01-01

    School readiness and functioning in children diagnosed with Reactive Attachment Disorder (RAD) are important issues due to the dramatic impact RAD has on multiple areas of development. The negative impact of impaired or disrupted early relationships, characterized by extreme neglect, abuse, parental mental illness, domestic violence, and repeated…

  20. Lanthanide alkyl and silyl compounds: Synthesis, reactivity and catalysts for green

    SciTech Connect

    Pindwal, Aradhana

    2016-01-01

    The last few decades have witnessed enormous research in the field of organometallic lanthanide chemistry. Our research group has developed a few rare earth alkyl compounds containing tris(dimethylsilyl)methyl ligand and explored their reactivity. This thesis focusses on extending the study of lanthanide alkyl and silyl compounds to develop strategies for their synthesis and explore their reactivity and role as catalysts in processes such as hydrosilylation and cross-dehydrocoupling.

  1. Identification and Optimization of Short Helical Peptides with Novel Reactive Functionality as Catalysts for Acyl Transfer by Reactive Tagging

    DTIC Science & Technology

    2014-01-21

    spectrograms, reactive tag synthesis and their physical data, library hits mass-spectrograms, CD spectra, NOE spectra, cartoon representations of peptide...with reactive tag RT2 to look for hits that additionally have competitive deacylation properties . In this mode, the tagging time was extended so that...In prin- ciple, beads displaying a fast k1 (acylation) and a competent deacylation (k3) should have good catalytic properties . This two step treatment

  2. Design and synthesis of reactive separation systems. Final report

    SciTech Connect

    Doherty, M.F.

    1992-12-31

    During the last decade there has been a rapid upturn in interest in reactive distillation. The chemical process industry recognizes the favorable economics of carrying out reaction simultaneously with distillation for certain classes of reacting systems, and many new processes have been built based on this technology. Interest is also increasing by academics and software vendors. Systematic design methods for reactive distillation systems have only recently begun to emerge. In this report we survey the available design techniques and point out the contributions made by our group at the University of Massachusetts.

  3. Synthesis and Reactivity of Aluminized Fluorinated Acrylic (AIFA) Nanocomposites (Postprint)

    DTIC Science & Technology

    2012-06-18

    REACTIVITY OF ALUMINIZED FLUORINATED ACRYLIC (ALFA) NANOCOMPOSITES (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...the nano Al throughout the material, the composite was compounded for 3 min in a DACA Instruments benchtop twin screw extruder at 150 C. The com

  4. Synthesis and processing of composites by reactive metal penetration

    SciTech Connect

    Loehman, R.E.; Ewsuk, K.G.; Tomsia, A.P.

    1995-05-01

    Ceramic-metal composites are being developed because their high stiffness-to weight ratios, good fracture toughness, and variable electrical and thermal properties give them advantages over more conventional materials. However, because ceramic-metal composite components presently are more expensive than monolithic materials, improvements in processing are required to reduce manufacturing costs. Reactive metal penetration is a promising new method for making ceramic- and metal-matrix composites that has the advantage of being inherently a net-shape process. This technique, once fully developed, will provide another capability for manufacturing the advanced ceramic composites that are needed for many light-weight structural and wear applications. The lower densities of these composites lead directly to energy savings in use. Near-net-shape fabrication of composite parts should lead to additional savings because costly and energy intensive grinding and machining operations are significantly reduced, and the waste generated from such finishing operations is minimized. The goals of this research program are: (1) to identify feasible compositional systems for making composites by reactive metal penetration; (2) to understand the mechanism(s) of composite formation by reactive metal penetration; and (3) to learn how to control and optimize reactive metal penetration for economical production of composites and composite coatings.

  5. Simple Molecular Reactive Force Field for Metal-Organic Synthesis.

    PubMed

    Andrejevic, Jovana; Stevenson, James; Clancy, Paulette

    2016-02-09

    For colloidal quantum dots to transition from research laboratories to deployment as optical and electronic products, there will be a need to scale-up their production to large-scale manufacturing processes. This demand increases the need to understand their formation via a molecular representation of the nucleation of lead sulfide (PbS) quantum dot systems passivated by lead oleate complexes. We demonstrate the effectiveness of a new type of reactive potential, custom-made for this system, that is drawn from simple Morse, Lennard-Jones, and Coulombic components, which can reproduce reactions across a broad range of PbS quantum dot sizes with good accuracy. We validate the capability of this model to capture reactive systems by comparison to ab initio calculations for a reaction between two dots.

  6. Integrated reactive absorption process for synthesis of fatty esters.

    PubMed

    Kiss, Anton Alexandru; Bildea, Costin Sorin

    2011-01-01

    Reactive separations using green catalysts offer great opportunities for manufacturing fatty esters, involved in specialty chemicals and biodiesel production. Integrating reaction and separation into one unit provides key benefits such as: simplified operation, no waste, reduced capital investment and low operating costs. This work presents a novel heat-integrated reactive absorption process that eliminates all conventional catalyst related operations, efficiently uses the raw materials and equipment, and considerably reduces the energy requirements for biodiesel production--85% lower as compared to the base case. Rigorous simulations based on experimental results were carried out using Aspen Plus and Dynamics. Despite the high degree of integration, the process is well controllable using an efficient control structure proposed in this work. The main results are provided for a plant producing 10 ktpy fatty acid methyl esters from methanol and waste vegetable oil with high free fatty acids content, using sulfated zirconia as solid acid catalyst.

  7. Oxetanes: Recent Advances in Synthesis, Reactivity, and Medicinal Chemistry.

    PubMed

    Bull, James A; Croft, Rosemary A; Davis, Owen A; Doran, Robert; Morgan, Kate F

    2016-10-12

    The four-membered oxetane ring has been increasingly exploited for its contrasting behaviors: its influence on physicochemical properties as a stable motif in medicinal chemistry and its propensity to undergo ring-opening reactions as a synthetic intermediate. These applications have driven numerous studies into the synthesis of new oxetane derivatives. This review takes an overview of the literature for the synthesis of oxetane derivatives, concentrating on advances in the last five years up to the end of 2015. These methods are clustered by strategies for preparation of the ring and further derivatization of preformed oxetane-containing building blocks. Examples of the use of oxetanes in medicinal chemistry are reported, including a collation of oxetane derivatives appearing in recent patents for medicinal chemistry applications. Finally, examples of oxetane derivatives in ring-opening and ring-expansion reactions are described.

  8. Tuning Energetic Material Reactivity Using Surface Functionalization of Aluminum Fuels

    DTIC Science & Technology

    2012-10-30

    of thermites, aluminum synthesis, aluminum fluoropolymer combustion, acid coatings Keerti S. Kappagantula, Cory Farley, Michelle L. Pantoya, Jillian... Michelle Pantoya 806-742-3563 3. DATES COVERED (From - To) Standard Form 298 (Rev 8/98) Prescribed by ANSI Std. Z39.18 - Tuning Energetic Material...Functionalization of Aluminum Fuels Keerti S. Kappagantula,† Cory Farley,† Michelle L. Pantoya,*,† and Jillian Horn‡ †Department of Mechanical Engineering, Texas

  9. Synthesis and processing of composites by reactive metal penetration

    SciTech Connect

    Loehman, R.E.; Ewsuk, K.G.; Tomsia, A.P.

    1997-04-01

    Achieving better performance in commercial products and processes often is dependent on availability of new and improved materials. Ceramic-metal composites have advantages over more conventional materials because of their high stiffness-to-weight ratios, good fracture toughness, and because their electrical and thermal properties can be varied through control of their compositions and microstructures. However, ceramic composites will be more widely used only when their costs are competitive with other materials and when designers have more confidence in their reliability. Over the past four years reactive metal penetration has been shown to be a promising technique for making ceramic and metal-matrix composites to near-net-shape with control of both composition and microstructure. It appears that, with sufficient development, reactive metal penetration could be an economical process for manufacturing many of the advanced ceramic composites that are needed for light-weight structural and wear applications for transportation and energy conversion devices. Near-net-shape fabrication of parts is a significant advantage because costly and energy intensive grinding and machining operations are substantially reduced, and the waste generated from such finishing operations is minimized. The most promising compositions to date consist of Al and Al{sub 2}O{sub 3}; thus, these composites should be of particular interest to the aluminum industry. The goals of this ceramic-metal composite research and development program are: (1) to identify compositions favorable for making composites by reactive metal penetration; (2) to understand the mechanism(s) by which these composites are formed; (3) to control and optimize the process so that composites and composite coatings can be made economically; and (4) to apply R&D results to problems of interest to the aluminum industry.

  10. Reactive multilayer synthesis of hard ceramic foils and films

    DOEpatents

    Makowiecki, D.M.; Holt, J.B.

    1996-02-13

    A method is disclosed for synthesizing hard ceramic materials such as carbides, borides and aluminides, particularly in the form of coatings provided on another material so as to improve the wear and abrasion performance of machine tools, for example. The method involves the sputter deposition of alternating layers of reactive metals with layers of carbon, boron, or aluminum and the subsequent reaction of the multilayered structure to produce a dense crystalline ceramic. The material can be coated on a substrate or formed as a foil which can be coiled as a tape for later use.

  11. Reactive multilayer synthesis of hard ceramic foils and films

    SciTech Connect

    Makowiecki, D.M.; Holt, J.B.

    1993-12-31

    Disclosed is method for synthesizing hard ceramic materials such as carbides, borides and aluminides, particularly in the form of coatings provided on another material so as to improve the wear and abrasion performance of machine tools, for example. Method involves the sputter deposition of alternating layers of reactive metals with layers of carbon, boron, or aluminum and the subsequent reaction of the multilayered structure to produce a dense crystalline ceramic. The material can be coated on a substrate or formed as a foil which can be coiled as a tape for later use.

  12. Reactive multilayer synthesis of hard ceramic foils and films

    DOEpatents

    Makowiecki, Daniel M.; Holt, Joseph B.

    1996-01-01

    A method for synthesizing hard ceramic materials such as carbides, borides nd aluminides, particularly in the form of coatings provided on another material so as to improve the wear and abrasion performance of machine tools, for example. The method involves the sputter deposition of alternating layers of reactive metals with layers of carbon, boron, or aluminum and the subsequent reaction of the multilayered structure to produce a dense crystalline ceramic. The material can be coated on a substrate or formed as a foil which can be coild as a tape for later use.

  13. Synthesis and characterization of organotin containing copolymers: reactivity ratio studies.

    PubMed

    Al-Deyab, Salem S; Al-Hazmi, Ali Mohsen; El-Newehy, Mohamed H

    2010-03-12

    Organotin monomers containing dibutyltin groups--dibutyltin citraconate (DBTC) as a new monomer and dibutyltin maleate (DBTM)--were synthesized. Free radical copolymerizations of the organotin monomers with styrene (ST) and butyl acrylate (BA) were performed. The overall conversion was kept low (< or = 15% wt/wt) for all studied samples and the copolymers composition was determined from tin analysis using the Gillman and Rosenberg method. The reactivity ratios were calculated from the copolymer composition using the Fineman-Ross (FR) method. The synthesized monomers were characterized by elemental analysis, 1H-, 13C-NMR and FTIR spectroscopy.

  14. Synthesis of belite cement clinker of high hydraulic reactivity

    SciTech Connect

    Kacimi, Larbi Simon-Masseron, Angelique Salem, Souria Ghomari, Abdelhamid Derriche, Zoubir

    2009-07-15

    This study is concerned with the increase of the cooling rate of belite clinker, by using the water quenching for the chemical stabilization of reactive belite, which improves the hydraulic properties of this clinker. The addition of adequate mineralizers, as NaF and Fe{sub 2}O{sub 3}, contributes to the improvement of the clinker properties obtained at low burning temperature. X-ray fluorescence spectroscopy, X-ray diffraction analysis and optical microscopy were used to determine the chemical and mineralogical compositions of this clinker. The samples were analyzed by means of a scanning electronic microscope connected with an energy-dispersive X-ray spectrometer to detect the composition of the belite phase and its morphology. Physical and mechanical properties of this clinker cement were determined. The results show that the belite clinker obtained at 1150 {sup o}C, with lime saturation factor 0.67, is characterized by a great hydraulic reactivity, similar to that of the ordinary alite clinker. The addition of 2% of NaF and the water quenching improved the chemical, mineralogical and structural properties, while improving the cement hydraulic properties.

  15. Synthesis and Reactivity of 4′-Deoxypentenosyl Disaccharides

    PubMed Central

    2015-01-01

    4-Deoxypentenosides (4-DPs) are versatile synthons for rare or higher-order pyranosides, and they provide an entry for structural diversification at the C5 position. Previous studies have shown that 4-DPs undergo stereocontrolled DMDO oxidation; subsequent epoxide ring-openings with various nucleophiles can proceed with both anti or syn selectivity. Here, we report the synthesis of α- and β-linked 4′-deoxypentenosyl (4′-DP) disaccharides, and we investigate their post-glycosylational C5′ additions using the DMDO oxidation/ring-opening sequence. The α-linked 4′-DP disaccharides were synthesized by coupling thiophenyl 4-DP donors with glycosyl acceptors using BSP/Tf2O activation, whereas β-linked 4′-DP disaccharides were generated by the decarboxylative elimination of glucuronyl disaccharides under microwave conditions. Both α- and β-linked 4′-DP disaccharides could be epoxidized with high stereoselectivity using DMDO. In some cases, the α-epoxypentenosides could be successfully converted into terminal l-iduronic acids via the syn addition of 2-furylzinc bromide. These studies support a novel approach to oligosaccharide synthesis, in which the stereochemical configuration of the terminal 4′-DP unit is established at a post-glycosylative stage. PMID:24797640

  16. Synthesis of RuAl by reactive powder processing

    NASA Astrophysics Data System (ADS)

    Wolff, I. M.

    1996-11-01

    The unusual combination of high-temperature strength and room-temperature ductility makes compounds based on RuAl attractive for structural applications. Difficulties inherent in the manufacture of RuAl by melt processing can be circumvented by powder metallurgical (PM) techniques. The present work shows that reactive hot isostatic pressing (RHIPing) based on the self-propagating exothermic reaction of the constituent powders allows homogeneous, high-density material to be made. Controlled process parameters include green density, prior degassing, the powder size distribution, heating rate, pressure, and homogenizing schedule. The nature of the reaction products was found to be determined primarily by the applied pressure during combustion. While concurrent pressure is required to ensure densification, pressurization leads to the formation of a host of nonequilibrium phases that necessitate extended homogenizing practices to drive the reaction to completion. The readily assimilable process parameters allow the production of structural components based on RuAl to be envisaged.

  17. Synthesis of Fe carbides species by reactive milling

    NASA Astrophysics Data System (ADS)

    Lodya, J. A. L.; Gericke, H.; Ngubane, J.; Dlamini, T. H.

    2009-04-01

    The formation of iron carbides by reactive milling of α-Fe and C powders is reported. The products formed were analyzed by Mössbauer spectroscopy and X-ray diffraction. It was found that iron carbide phases start forming after an incubation period of about 3 h depending on the ball-to-powder weight ratio (BPR). Carbide amounts increased with increasing milling time while α-Fe content decreased. Energy transfer increased with increasing BPR and high BPR resulted in an increase in the reaction rate. Although it was not possible to selectively synthesise a specific Fe x C phase, samples containing predominantly one type of carbide phase, either Hägg carbide or cementite, were successfully prepared. The formation of the different iron carbide phases is discussed within the context of the Fe-C phase diagram for non-equilibrium processes.

  18. Reactive oxygen species produced via plasma membrane NADPH oxidase regulate anthocyanin synthesis in apple peel.

    PubMed

    Zhang, Jiangli; Chen, Changsheng; Zhang, Di; Li, Houhua; Li, Pengmin; Ma, Fengwang

    2014-11-01

    Solar ultraviolet irradiation regulates anthocyanin synthesis in apple peel by modulating the production of reactive oxygen species via plasma membrane NADPH oxidase instead of other pathways. The synthesis of anthocyanin in apple peels is dependent upon solar irradiation. Using 3-mm commercial glass to attenuate solar UV-A and UV-B light, we confirmed that solar UV irradiation regulated anthocyanin synthesis in apple peels after exposing previously bagged fruit to sunlight. During sunlight exposure, UV attenuation did not affect the expression of MdHY5, MdCOP1, or MdCRY2, but significantly lowered plasma membrane NADPH oxidase activity and superoxide anion concentrations. UV attenuation also reduced the expression levels of MdMYB10, MdPAL, MdCHS, MdF3H, MdDFR, MdANS and MdUFGT1, UDP-glycose:flavonoid 3-O-glycosyltransferase (UFGT) activity, and local concentrations of anthocyanin and quercetin-3-glycoside. In contrast, exogenous application of hydrogen peroxide could enhance anthocyanin and quercetin-3-glycoside synthesis. Xanthophyll cycle pool size on a chlorophyll basis was higher but its de-epoxidation was lower under direct sunlight irradiation than that under UV-attenuating conditions. This suggests that reactive oxygen species (ROS) produced in chloroplast are not major contributors to anthocyanin synthesis regulation. Inhibition of plasma membrane NADPH oxidase activity lowered the production of ROS through this mechanism, significantly inhibited the synthesis of anthocyanin, and increased the total production of ROS in apple peel under direct sunlight irradiation, suggesting that ROS produced via plasma membrane NADPH oxidase regulates anthocyanin synthesis. In summary, solar UV irradiation regulated anthocyanin synthesis in apple peels by modulating the production of ROS via plasma membrane NADPH oxidase.

  19. Dithiolopyranthione Synthesis, Spectroscopy and an Unusual Reactivity with DDQ

    PubMed Central

    Pimkov, Igor V.; Nigam, Archana; Venna, Kiran; Solntsev, Pavlo V.; Nemykin, Victor N.

    2014-01-01

    The bicyclic pyran thiolone tetrahydro-3αH-[1,3]dithiolo[4,5-β]pyran-2-thione (3a) engages in a highly unusual fragmentation in the presence of DDQ. The pyran thiolone, 3a, was synthesized by chlorination of 3,4-dihydro-2H-pyran (1), followed by condensing with CS2 and NaSH. Reaction of 3a with DDQ generates the isomerized pyran thiolone tetrahydro-3αH-[1,3]dithiolo[4,5-β]pyran-2-thione (3b) and 4-benzyl-5-(3-hydroxypropyl)-1,3-dithiole-2-thione (4) via a deep-seated rearrangement. The identity of 3b was confirmed by single crystal X-ray analysis: P21/c, a=5.807(9) Å, b = 12.99(2) Å, c = 11.445(15), β=113.23(6)°. Mechanistic experiments and computational insight is used to explain the likely sequence of events in the highly unusual formation of 4. Collectively, these results establish fundamental reactivity patterns for further research in this area. PMID:25328243

  20. Synthesis of Alumina Thin Films Using Reactive Magnetron Sputtering Method

    NASA Astrophysics Data System (ADS)

    Angarita, G.; Palacio, C.; Trujillo, M.; Arroyave, M.

    2017-06-01

    Alumina (Al2O3) thin films were deposited on Si (100) by Magnetron Sputtering in reactive conditions between an aluminium target and oxygen 99.99% pure. The plasma was formed employing Argon with an R.F power of 100 W, the dwelling time was 3 hours. 4 samples were produced with temperatures between 350 and 400 ºC in the substrate by using an oxygen flow of 2 and 8 sccm, the remaining parameters of the process were fixed. The coatings and substrates were characterized using Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), X-ray diffraction (XRD) and Energy Dispersive Spectroscopy (EDS) in order to compare their properties before and after deposition. The films thicknesses were between 47 and 70 nm. The results show that at high oxygen flow the alumina structure prevails in the coatings while at lower oxygen flow only aluminum is deposited in the coatings. It was shown that the temperature increases grain size and roughness while decreasing the thicknesses of the coatings.

  1. REACTIVITY OF THE GERMANIUM SURFACE: Chemical Passivation and Functionalization

    NASA Astrophysics Data System (ADS)

    Loscutoff, Paul W.; Bent, Stacey F.

    2006-05-01

    With the rapidly changing materials needs of modern microelectronics, germanium provides an opportunity for future-generation devices. Controlling germanium interfaces will be essential for this purpose. We review germanium surface reactivity, beginning with a description of the most commonly used surfaces, Ge(100) and Ge(111). An analysis of oxide formation shows why the poor oxide properties have hindered practical use of germanium to date. This is followed by an examination of alternate means of surface passivation, with particular attention given to sulfide, chloride, and hydride termination. Specific tailoring of the interface properties is possible through organic functionalization. The few solution functionalization methods that have been studied are reviewed. Vacuum functionalization has been studied to a much greater extent, with dative bonding and cycloaddition reactions emerging as principle reaction mechanisms. These are reviewed through molecular reaction studies that demonstrate the versatility of the germanium surface.

  2. Reactivity of carbides in synthesis of MgB 2 bulks

    NASA Astrophysics Data System (ADS)

    Yamamoto, Akiyasu; Shimoyama, Jun-ichi; Ueda, Shinya; Horii, Shigeru; Kishio, Kohji

    2006-10-01

    The reactivity of various carbides (B4C, Al4C3, SiC, TiC, ZrC, NbC, Mo2C, HfC and WC) with magnesium and boron in synthesis of MgB2 was systematically studied. Decreases in the a-axis length and transition temperature were observed in all the carbide doped MgB2 bulks, reflecting a certain amount of carbon substituted for boron site in MgB2. The reactivity of each carbide estimated by the carbon content in MgB2 was found to be different depending on the chemical stability. Our results suggest that carbon content in MgB2 lattice can be controlled to its optimal doping level by adjusting synthesis conditions and selection of doping reagents.

  3. An experimental evaluation of the instrumented flux synthesis method for the real-time estimation of reactivity. Final report

    SciTech Connect

    Hughes, J.C.; Henry, A.F.; Lanning, D.D.; Bernard, J.A.

    1996-01-01

    One method of determining the flux density is flux synthesis which approximates the flux in the core by linear combinations of precomputed shape functions. In traditional flux synthesis, the unknown mixing coefficients are determined using a weighted residual method of solving the diffusion equation. In the instrumented synthesis method, the mixing coefficients are determined using count rates from neutron detectors in the core. In this way the mixing coefficients are linked to conditions in the reactor. Using the synthesized flux, kinetics parameters, notably reactivity, can be calculated in real time. An experimental evaluation has been performed in the Massachusetts Institute of Technology Reactor, MITR-II. Detector measurements have been collected using fission chambers placed at the periphery of the core. The reactor was put into a number of various conditions, both static and transient, and data were collected using a digital acquisition system for later combination with shape functions. Transients included increasing power, decreasing power, and a reactor scram. The shape functions were generated using Version 3.0 of the QUARTZ code, a quadratic nodal diffusion theory code in triangular-Z geometry. Supernodal analysis algorithms have been added to the original program, along with subroutines to guarantee diagonal dominance of the leakage matrix in the finite difference or quadratic current approximations in the coarse mesh. The agreement between coarse mesh and fine mesh in all cases is excellent, with finite difference coarse mesh solutions generally slightly better. The synthesis method has been shown to accurately reflect the changes from an initial condition by combining representative flux shapes. It can be concluded that, with proper calibration of the measurement system and inclusion of representative flux shapes, the instrumented synthesis method will properly predict the flux in the core under a number of conditions.

  4. Symposium Supramolecular Assemblies on Surface: Nanopatterning, Functionality and Reactivity

    DTIC Science & Technology

    2016-05-19

    functional supramolecular structures at surfaces as well as surfaced-confined reactions, including the bottom-up synthesis of linear conjugated polymers and...two-dimensional polymers . (a) Papers published in peer-reviewed journals (N/A for none) Enter List of papers submitted or published that acknowledge...Anna Organized metal  nanoparticle  assemblies by block copolymer templating Université Laval 10:00 AM 10:20 AM Frida 20 Tahara, Kazukuni Multi‐component

  5. Synthesis and tunable reactivity of N-heterocyclic germylene.

    PubMed

    Xiong, Yun; Yao, Shenglai; Driess, Matthias

    2012-09-01

    Modifying the β-diketimine ligand LH 1 (LH=[ArN=C(Me)-CH=C(Me)-NHAr], Ar=2,6-iPr(2)C(6)H(3)) through replacement of the proton in 3-position by a benzyl group (Bz) leads to the new (Bz)LH ligand 2, which could be isolated in 77% yield. According to (1) H NMR spectroscopy, 2 is a mixture of the bis(imino) form [(ArN=C(Me)](2)CH(Bz) 2a and its tautomer [ArN=C(Me)-C(Bz)=C(Me)NHAr] 2b. Nevertheless, lithiation of the mixture of 2a and 2b affords solely the N-lithiated β-diketiminate [ArN=C(Me)-C(Bz)=C(Me)-NLiAr], (Bz)LLi 3. The latter reacts readily with GeCl(2)· dioxane to form the chlorogermylene (Bz)LGeCl 4, which serves as a precursor for a new zwitterionic germylene by dehydrochlorination with LiN(SiMe(3))(2). This reaction leads to the zwitterionic germylene (Bz)L'Ge: 5 ((Bz)L'=ArNC(=CH(2))C(Bz)=C(Me)NAr) which could be isolated in 83% yield. The benzyl group has a distinct influence on the reactivity of zwitterionic 5 in comparison to its benzyl-free analogue, as shown by the reaction of 5 with phenylacetylene, which yields solely the 1,4-addition product 6, that is, the alkynyl germylene (Bz)LGeCCPh. Compounds 2-6 have been fully characterized by multinuclear NMR spectroscopy, mass spectrometry, elemental analyses, and single-crystal X-ray diffraction analyses.

  6. The synthesis, characterization, and reactivity of some alkyne, vinylidene, and butatrienylidene complexes of ruthenium

    SciTech Connect

    Lomprey, J.R.

    1993-01-01

    Cumulene complexes of ruthenium were studied in regard to their preparation, characterization, and reactivity. This work is divided into two parts: first, a study of the alkyne to vinylidene isomerization on a ruthenium (II) center, and second the study of the synthesis of metal butatrienylidene complexes. The isomeric C[sub 2]H[sub 2] complexes [Ru([eta][sup 2]-HC[triple bond]CH) (PMe[sub 2]-Ph)[sub 2] (Cp)] [BF[sub 4

  7. Chirality-Selective Functionalization of Semiconducting Carbon Nanotubes with a Reactivity-Switchable Molecule.

    PubMed

    Powell, Lyndsey R; Kim, Mijin; Wang, YuHuang

    2017-09-13

    Chirality-selective functionalization of semiconducting single-walled carbon nanotubes (SWCNTs) has been a difficult synthetic goal for more than a decade. Here we describe an on-demand covalent chemistry to address this intriguing challenge. Our approach involves the synthesis and isolation of a chemically inert diazoether isomer that can be switched to its reactive form in situ by modulation of the thermodynamic barrier to isomerization with pH and visible light that resonates with the optical frequency of the nanotube. We found that it is possible to completely inhibit the reaction in the absence of light, as determined by the limit of sensitive defect photoluminescence (less than 0.01% of the carbon atoms are bonded to a functional group). This optically driven diazoether chemistry makes it possible to selectively functionalize a specific SWCNT chirality within a mixture. Even for two chiralities that are nearly identical in diameter and electronic structure, (6,5)- and (7,3)-SWCNTs, we are able to activate the diazoether compound to functionalize the less reactive (7,3)-SWCNTs, driving the chemical reaction to near exclusion of the (6,5)-SWCNTs. This work opens opportunities to chemically tailor SWCNTs at the single chirality level for nanotube sorting, on-chip passivation, and nanoscale lithography.

  8. The Functional Role of Reactive Stroma in Benign Prostatic Hyperplasia

    PubMed Central

    Schauer, Isaiah G.; Rowley, David R.

    2011-01-01

    The human prostate gland is one of the only internal organs that continue to enlarge throughout adulthood. The specific mechanisms that regulate this growth, as well as the pathological changes leading to the phenotype observed in the disease benign prostatic hyperplasia (BPH), are essentially unknown. Recent studies and their associated findings have made clear that many complex alterations occur, involving persistent and chronic inflammation, circulating hormonal level deregulation, and aberrant wound repair processes. BPH has been etiologically characterized as a progressive, albeit discontinuous, hyperplasia of both the glandular epithelial and stromal cell compartments coordinately yielding an expansion of the prostate gland and clinical symptoms. Interestingly, the inflammatory and repair responses observed in BPH are also key components of general wound repair in post-natal tissues. These responses include altered expression of chemokines, cytokines, matrix remodeling factors, chronic inflammatory processes, altered immune surveillance and recognition, as well as the formation of a prototypical ‘reactive’ stroma which is similar to that observed across various fibroplasias and malignancies of a variety of tissue sites. Stromal tissue, both embryonic mesenchyme, and adult reactive stroma myofibroblasts, has been shown to exert potent and functional regulatory control over epithelial proliferation and differentiation as well as immunoresponsive modulation. Thus, the functional biology of a reactive stroma, within the context of an adult disease typified by epithelial and stromal aberrant hyperplasia, is critical to understand within the context of prostate disease and beyond. The mechanisms that regulate reactive stroma biology in BPH represent targets of opportunity for new therapeutic approaches that may extend to other tissue contexts. Accordingly, this review seeks to address the dissection of important factors, signaling pathways, genes, and other

  9. Synthesis and Reactivity of Tripodal Complexes Containing Pendant Bases

    SciTech Connect

    Blacquiere, Johanna M.; Pegis, Michael L.; Raugei, Simone; Kaminsky, Werner; Forget, Amelie; Cook, Sarah; Taguchi, Taketo; Borovik, Andrew S.; Mayer, James M.

    2014-09-02

    The synthesis of a new tripodal ligand family is reported, with tertiary-amine groups in the second-coordination sphere. The ligands are tris(amido)amine derivatives, with the pendant amines attached via a peptide coupling strategy. They were designed to be used in new catalysts for the oxygen reduction reaction (ORR), in which the pendant acid/base group could improve catalyst performance. Two members of the new ligand family were each metallated with Co(II) and Zn(II) to afford trigonal monopyramidal complexes. Reaction of the cobalt complexes, [Co(L)]-, with dioxygen reversibly generates a small amount of a Co(III)-superoxo species, which was characterized by EPR. Protonation of the zinc complex Zn[N{CH2CH2NC(O)CH2N(CH2Ph)2}3)-– ([Zn(TNBn)]-) with one equivalent of acid occurs with displacement and dissociation of an amide ligand. Addition of excess acid to the any of the complexes [M(L)]- results in complete proteolysis and formation of the ligands H3L. This decomposition limits the use of these complexes as catalysts for the ORR. An alternative ligand with two pyridyl arms was also prepared but could not be metallated. These studies highlight the importance of stability of the primary-coordination sphere of ORR electrocatalysts to both oxidative and acidic conditions. This research was supported as part of the Center for Molecular Electrocatalysis, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences.

  10. Block of glucocorticoid synthesis during re-activation inhibits extinction of an established fear memory

    PubMed Central

    Blundell, Jacqueline; Blaiss, Cory A.; Lagace, Diane C.; Eisch, Amelia J.; Powell, Craig M.

    2012-01-01

    Background The pharmacology of traumatic memory extinction has not been fully characterized despite its potential as a therapeutic target for established, acquired anxiety disorders, including post-traumatic stress disorder (PTSD). Here we examine the role of endogenous glucocorticoids in traumatic memory extinction. Methods Male C57BL/6J mice were injected with corticosterone (10 mg/kg, i.p.) or metyrapone (50 mg/kg, s.c.) during re-activation of a contextual fear memory, and compared to vehicle groups (N = 10–12 per group). To ensure that metyrapone was blocking corticosterone synthesis, we measured corticosterone levels following re-activation of a fear memory in metyrapone- and vehicle-treated animals. Results Corticosterone administration following extinction trials caused a long-lasting inhibition of the original fear memory trace. In contrast, blockade of corticosteroid synthesis with metyrapone prior to extinction trials enhanced retrieval and prevented extinction of context-dependent fear responses in mice. Further behavioral analysis suggested that the metyrapone enhancement of retrieval and prevention of extinction were not due to non-specific alterations in locomotor or anxiety-like behavior. In addition, the inhibition of extinction by metyrapone was rescued by exogenous administration of corticosterone following extinction trials. Finally, we confirmed that the rise in corticosterone during re-activation of a contextual fear memory was blocked by metyrapone. Conclusions We demonstrate that extinction of a classical contextual fear memory is dependent on endogenous glucocorticoid synthesis during re-activation of a fear memory. Our data suggest that decreased glucocorticoids during fear memory re-activation may contribute to the inability to extinguish a fear memory, thus contributing to one of the core symptoms of PTSD. PMID:21333745

  11. Block of glucocorticoid synthesis during re-activation inhibits extinction of an established fear memory.

    PubMed

    Blundell, Jacqueline; Blaiss, Cory A; Lagace, Diane C; Eisch, Amelia J; Powell, Craig M

    2011-05-01

    The pharmacology of traumatic memory extinction has not been fully characterized despite its potential as a therapeutic target for established, acquired anxiety disorders, including post-traumatic stress disorder (PTSD). Here we examine the role of endogenous glucocorticoids in traumatic memory extinction. Male C57BL/6J mice were injected with corticosterone (10 mg/kg, i.p.) or metyrapone (50 mg/kg, s.c.) during re-activation of a contextual fear memory, and compared to vehicle groups (N=10-12 per group). To ensure that metyrapone was blocking corticosterone synthesis, we measured corticosterone levels following re-activation of a fear memory in metyrapone- and vehicle-treated animals. Corticosterone administration following extinction trials caused a long-lasting inhibition of the original fear memory trace. In contrast, blockade of corticosteroid synthesis with metyrapone prior to extinction trials enhanced retrieval and prevented extinction of context-dependent fear responses in mice. Further behavioral analysis suggested that the metyrapone enhancement of retrieval and prevention of extinction were not due to non-specific alterations in locomotor or anxiety-like behavior. In addition, the inhibition of extinction by metyrapone was rescued by exogenous administration of corticosterone following extinction trials. Finally, we confirmed that the rise in corticosterone during re-activation of a contextual fear memory was blocked by metyrapone. We demonstrate that extinction of a classical contextual fear memory is dependent on endogenous glucocorticoid synthesis during re-activation of a fear memory. Our data suggest that decreased glucocorticoids during fear memory re-activation may contribute to the inability to extinguish a fear memory, thus contributing to one of the core symptoms of PTSD. Copyright © 2011 Elsevier Inc. All rights reserved.

  12. Low-reactive circulating fluidized bed combustion (CFBC) fly ashes as source material for geopolymer synthesis.

    PubMed

    Xu, Hui; Li, Qin; Shen, Lifeng; Zhang, Mengqun; Zhai, Jianping

    2010-01-01

    In this contribution, low-reactive circulating fluidized bed combustion (CFBC) fly ashes (CFAs) have firstly been utilized as a source material for geopolymer synthesis. An alkali fusion process was employed to promote the dissolution of Si and Al species from the CFAs, and thus to enhance the reactivity of the ashes. A high-reactive metakaolin (MK) was also used to consume the excess alkali needed for the fusion. Reactivities of the CFAs and MK were examined by a series of dissolution tests in sodium hydroxide solutions. Geopolymer samples were prepared by alkali activation of the source materials using a sodium silicate solution as the activator. The synthesized products were characterized by mechanical testing, scanning electron microscopy (SEM), X-ray diffractography (XRD), as well as Fourier transform infrared spectroscopy (FTIR). The results of this study indicate that, via enhancing the reactivity by alkali fusion and balancing the Na/Al ratio by additional aluminosilicate source, low-reactive CFAs could also be recycled as an alternative source material for geopolymer production.

  13. Low-reactive circulating fluidized bed combustion (CFBC) fly ashes as source material for geopolymer synthesis

    SciTech Connect

    Xu Hui; Li Qin; Shen Lifeng; Zhang Mengqun; Zhai Jianping

    2010-01-15

    In this contribution, low-reactive circulating fluidized bed combustion (CFBC) fly ashes (CFAs) have firstly been utilized as a source material for geopolymer synthesis. An alkali fusion process was employed to promote the dissolution of Si and Al species from the CFAs, and thus to enhance the reactivity of the ashes. A high-reactive metakaolin (MK) was also used to consume the excess alkali needed for the fusion. Reactivities of the CFAs and MK were examined by a series of dissolution tests in sodium hydroxide solutions. Geopolymer samples were prepared by alkali activation of the source materials using a sodium silicate solution as the activator. The synthesized products were characterized by mechanical testing, scanning electron microscopy (SEM), X-ray diffractography (XRD), as well as Fourier transform infrared spectroscopy (FTIR). The results of this study indicate that, via enhancing the reactivity by alkali fusion and balancing the Na/Al ratio by additional aluminosilicate source, low-reactive CFAs could also be recycled as an alternative source material for geopolymer production.

  14. Role of reactive nitrogen species in blood platelet functions.

    PubMed

    Olas, Beata; Wachowicz, Barbara

    2007-12-01

    Blood platelets, in analogy to other circulating blood cells, can generate reactive oxygen/nitrogen species (ROS/RNS) that may behave as second messengers and may regulate platelet functions. Accumulating evidence suggest a role of ROS/RNS in platelet activation. On the other hand, an increased production of ROS/RNS causes oxidative stress, and thus, may contribute to the development of different diseases, including vascular complications, inflammatory and psychiatric illnesses. Oxidative stress in platelets leads to chemical changes in a wide range of their components, and platelet proteins may be initial targets of ROS/RNS action. It has been demonstrated that reaction of proteins with ROS/RNS results in the oxidation and nitration of some amino acid residues, formation of aggregates or fragmentation of proteins. In oxidized proteins new carbonyl groups and protein hydroperoxides are also formed. In platelets, low molecular weight thiols such as glutathione (GSH), cysteine and cysteinylglycine and protein thiols may be also target for ROS/RNS action. This review describes the chemical structure and biological activities of reactive nitrogen species, mainly nitric oxide ((*)NO) and peroxynitrite (ONOO(-)) and their effects on blood platelet functions, and the mechanisms involved in their action on platelets.

  15. Synthesis, characterization, and reactivity of sulfided hexanuclear molybdenum cluster compounds

    SciTech Connect

    Spink, D.

    1990-09-21

    Hexanuclear molybdenum clusters with mixed chloride and sulfide bridging ligands were prepared by reacting {alpha}-MoCl{sub 2} with sodium hydrosulfide in the presence of sodium butoxide. The resulting species, Mo{sub 6}Cl{sub (8-x)}S{sub x}{center dot}npy(x {congruent} 3.6, n {congruent} 4, py = pyridine), was pyrophoric and insoluble. The mixed sulfide chloride cluster species Mo{sub 6}S{sub 4}Cl{sub 4}{center dot}6OPEt{sub 3} and Mo{sub 6}S{sub {approximately}5}Cl{sub {approximately}3}{center dot}6PEt{sub 3} and Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3} were isolated and characterized. Phosphorus-31 nuclear magnetic resonance, electron paramagnetic resonance, and UV/visible spectra were obtained for each fraction. The completely sulfided cluster, Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3}, was prepared similarly and used in various experiments as a possible precursor to Chevrel phase materials of the type Mo{sub 6}S{sub 8}or M{sub n}Mo{sub 6}S{sub 8}. With the goal of removing all of the triethylphosphine ligands, Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3} was reacted with the transition metal carbonyls molybdenum hexacarbonyl and dicobalt octacarbonyl. Reaction on the molecular sulfide cluster with copper(I) chloride in toluene gave a completely insoluble product. The reaction of Mo{sub 6}S{sub 8}{center dot}6PEt{sub 3} with propylene sulfide gave a product whose infrared spectra showed only very weak peaks associated with coordinated triethylphosphine. The elemental analysis of this product fit the formula Mo{sub 6}S{sub 8}{center dot}5SPEt{sub 3}. Reactivity of the outer ligands of the Mo{sub 6}S{sub 8}{center dot}npy and Mo{sub 6}S{sub 8}{center dot}(6{minus}x)PrNH{sub x} clusters were investigated. Crystalline Mo{sub 6}S{sub 8}{center dot}6THT was recovered from the reaction of the n-propylamine derivative with THT. A crystal structure determination was done. 87 refs., 12 fig., 15 tabs.

  16. Bronchial Reactivity and Lung Function After World Trade Center Exposure.

    PubMed

    Aldrich, Thomas K; Weakley, Jessica; Dhar, Sean; Hall, Charles B; Crosse, Tesha; Banauch, Gisela I; Weiden, Michael D; Izbicki, Gabriel; Cohen, Hillel W; Gupta, Aanchal; King, Camille; Christodoulou, Vasilios; Webber, Mayris P; Zeig-Owens, Rachel; Moir, William; Nolan, Anna; Kelly, Kerry J; Prezant, David J

    2016-12-01

    World Trade Center (WTC)-exposed rescue/recovery workers endured massive respiratory insult from inhalation of particulate matter and gases, resulting in respiratory symptoms, loss of lung function, and, for many, bronchial hyperreactivity (BHR). The persistence of respiratory symptoms and lung function abnormalities has been well-documented, whereas persistence of BHR has not been investigated. A total of 173 WTC-exposed firefighters with bronchial reactivity measured within 2 years after September 11, 2001 (9/11) (baseline methacholine challenge test), were reevaluated in 2013 and 2014 (follow-up methacholine challenge test). FEV1 measurements were obtained from the late pre-9/11, early post-9/11, and late post-9/11 periods. Respiratory symptoms and corticosteroid treatment were recorded. Bronchial reactivity remained stable (within 1 doubling dilution) for most (n = 101, 58%). Sixteen of 28 (57%) with BHR (provocative concentration of methacholine producing a 20% decline in FEV1 <8 mg/mL) at baseline had BHR at follow-up, and an additional 27 of the 145 (19%) without BHR at baseline had BHR at follow-up. In multivariable models, we found that BHR baseline was strongly associated with BHR follow-up (OR, 6.46) and that BHR at follow-up was associated with an estimated 15.4 mL/y greater FEV1 decline than experienced by those without BHR at follow-up. Annual FEV1 decline was moderated by corticosteroid use. Persistent BHR and its deleterious influence on lung function suggest a role for airway inflammation in perpetuation of WTC-associated airway disease. In future massive occupational exposure to inorganic dust/gases, we recommend early and serial pulmonary function testing, including measurements of bronchial reactivity, when possible, and inhaled corticosteroid therapy for those with symptoms or pulmonary function tests consistent with airway disease. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

  17. Chemical reactivity analysis of deoxyribonucleosides and deoxyribonucleoside analogues (NRTIs): a first-principles density functional approach.

    PubMed

    Kumar, Vipin; Kishor, Shyam; Ramaniah, Lavanya M

    2012-08-01

    The structures, energetics, as well as several important chemical parameters, of antiretroviral drugs - nucleoside reverse transcriptase inhibitors (NRTIs) - and natural deoxyribonucleosides in both neutral, and positively and negatively charged states, are investigated. These studies are carried out within the frame work of first-principles density-functional theory (DFT), using the Becke-Lee-Yang-Parr (BLYP) generalized gradient corrections to the local spin density approximation exchange and correlation energy, norm-conserving pseudopotentials and a plane-wave expansion of Kohn-Sham orbitals. Conceptual DFT is used to determine global and local chemical reactivity parameters. Our results are in good agreement with the best available experiments to date. The variation in the bond lengths and bond angles on cation formation indicates that the electron is lost from the base part of these molecules. Further, the presence of the deoxyribose sugar moiety lowers their ionization potential and increases their electron affinity, in comparison to the isolated DNA base. The effectiveness of the drug action in terminating the viral DNA chain, is explained using the global reactivity parameters, by comparing the reactivities of the drug molecules with those of the competing deoxyribonucleosides. The widely followed clinical practice, of avoiding the simultaneous administration of certain drugs, is also explained from the hardness and softness parameters. For most of the drug molecules, our study validates the generally accepted wisdom, that monophosphorylation is the crucial reaction step in the phosphorylation reaction in DNA nucleotide synthesis.

  18. Synthesis, reactivity and application studies for different biolubricants.

    PubMed

    Salimon, Jumat; Abdullah, Bashar Mudhaffar; Yusop, Rahimi M; Salih, Nadia

    2014-03-10

    Vegetable oils have different unique properties owing to their unique chemical structure. Vegetable oils have a greater ability to lubricate and have higher viscosity indices. Therefore, they are being more closely examined as base oil for biolubricants and functional fluids. In spite of their many advantages, vegetable oils suffer from two major drawbacks of inadequate oxidative stability and poor low-temperature properties, which hinder their utilization as biolubricant base oils. Transforming alkene groups in fatty acids to other stable functional groups could improve the oxidative stability, whereas reducing structural uniformity of the oil by attaching alkyl side chains could improve the low-temperature performance. In that light, the epoxidation of unsaturated fatty acids is very interesting as it can provide diverse side chains arising from the mono- or di-epoxidation of the unsaturated fatty acid. Oxirane ring opening by an acid-catalyzed reaction with a suitable reagent provides interesting polyfunctional compounds.

  19. Synthesis, reactivity and application studies for different biolubricants

    PubMed Central

    2014-01-01

    Vegetable oils have different unique properties owing to their unique chemical structure. Vegetable oils have a greater ability to lubricate and have higher viscosity indices. Therefore, they are being more closely examined as base oil for biolubricants and functional fluids. In spite of their many advantages, vegetable oils suffer from two major drawbacks of inadequate oxidative stability and poor low-temperature properties, which hinder their utilization as biolubricant base oils. Transforming alkene groups in fatty acids to other stable functional groups could improve the oxidative stability, whereas reducing structural uniformity of the oil by attaching alkyl side chains could improve the low-temperature performance. In that light, the epoxidation of unsaturated fatty acids is very interesting as it can provide diverse side chains arising from the mono- or di-epoxidation of the unsaturated fatty acid. Oxirane ring opening by an acid-catalyzed reaction with a suitable reagent provides interesting polyfunctional compounds. PMID:24612780

  20. Vinylogous Reactivity of Enoldiazoacetates with Donor-Acceptor Substituted Hydrazones. Synthesis of Substituted Pyrazole Derivatives

    PubMed Central

    Xu, Xinfang; Zavalij, Peter Y.; Hu, Wenhao; Doyle, Michael P.

    2013-01-01

    A regiospecific synthesis of multi-functional pyrazoles has been developed from a cascade process triggered by Rh(II)-catalyzed dinitrogen extrusion from enoldiazoacetates with vinylogous nucleophilic addition followed by Lewis acid catalyzed cyclization and aromatization. PMID:23301562

  1. ortho-Quinol Acetate Chemistry - Reactivity towards Aryl-Based Nucleophiles and Applications to the Synthesis of Natural Products.

    PubMed

    Companys, Simon; Pouységu, Laurent; Peixoto, Philippe A; Chassaing, Stefan; Quideau, Stephane

    2017-03-10

    Two model ortho-quinol acetates were easily prepared by iodane-mediated acetoxylative phenol dearomatization and evaluated for their reactivity towards various aryl-based nucleophiles, i.e., aryl metallic reagents and phenolic derivatives. Novel modes of reactivity, allowing the formation of biaryl linkages, were revealed and here exploited for the synthesis of two natural phenolics.

  2. Functional significance of men's testosterone reactivity to social stimuli.

    PubMed

    Zilioli, Samuele; Bird, Brian M

    2017-10-01

    Rapid testosterone fluctuations in response to social stimuli are observed across a wide range of species, and the highly conserved nature of these fluctuations suggests an adaptive function. This paper reviews the current literature on testosterone reactivity, primarily in human males, and illustrates how life-history theory provides an adequate theoretical framework to interpret findings. The review is structured around supporting evidence suggesting that situations implicated in mating effort either directly (e.g., interactions with a mate) or indirectly (e.g., intrasexual competition) are generally associated with a brief elevation of testosterone, while situations implicated in parenting effort (e.g., nurturant interactions with offspring) are generally associated with a decline in testosterone. Further, we discuss how these fluctuations in testosterone have been linked to future behaviors, and how situational, motivational, and physiological variables moderate the interplay between social stimuli, testosterone reactivity, and behavior. Supporting the notion that testosterone can play a causal role in modulating behavior in response to social stimuli, we also summarize recent single administration studies examining the effects of testosterone on physiology, neurobiology, and behavior. A conceptual model provides links between supported findings, and hypothesized pathways requiring future testing. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Zero Valent Iron: Impact of Anions Present during Synthesis on Subsequent Nanoparticle Reactivity

    SciTech Connect

    Moore, Kirsten; Forsberg, Brady; Baer, Donald R.; Arnold, William A.; Penn, R. Lee

    2011-10-01

    Zero-valent iron particles are an effective remediation technology for groundwater contaminated with halogenated organic compounds. In particular, nano-scale zero-valent iron is a promising material for remediation due to its high specific surface area, which results in faster rate constants and more effective use of the iron. An aspect of iron nanoparticle reactivity that has not been explored is the impact of anions present during iron metal nanoparticle synthesis. Solutions containing chloride, phosphate, sulfate, and nitrate anions and ferric ions were used to generate iron oxide nanoparticles. The resulting materials were dialyzed to remove dissolved byproducts and then dried and reduced by hydrogen gas at high temperature. The reactivity of the resulting zero valent iron nanoparticles was quantified by monitoring the kinetics as well as products of carbon tetrachloride reduction, and significant differences in reactivity and chloroform yield were observed. The reactivity of nanoparticles prepared in the presence of sulfate and phosphate demonstrated the highest reactivity and chloroform yield. Furthermore, substantial variations in the solid-state products of oxidation (magnetite, iron sulfide, and goethite, among others) were also observed.

  4. Applications of the Conceptual Density Functional Theory Indices to Organic Chemistry Reactivity.

    PubMed

    Domingo, Luis R; Ríos-Gutiérrez, Mar; Pérez, Patricia

    2016-06-09

    Theoretical reactivity indices based on the conceptual Density Functional Theory (DFT) have become a powerful tool for the semiquantitative study of organic reactivity. A large number of reactivity indices have been proposed in the literature. Herein, global quantities like the electronic chemical potential μ, the electrophilicity ω and the nucleophilicity N indices, and local condensed indices like the electrophilic P k + and nucleophilic P k - Parr functions, as the most relevant indices for the study of organic reactivity, are discussed.

  5. Reactivities of vinyl azides and their recent applications in nitrogen heterocycle synthesis

    PubMed Central

    Hu, Bao; DiMagno, Stephen G.

    2015-01-01

    Nitrogen heterocycles are abundant in natural products and pharmaceuticals. An emerging interest among synthetic chemists is to apply vinyl azides as a pivotal three-atom synthon for the construction of structurally complex and diverse N-heterocyclic skeletons. The unique features of the azide group connected to an alkene moiety permit vinyl azides to function as electrophiles, nucleophiles, or radical acceptors; their access to diverse reaction pathways provides great opportunities to generate highly reactive intermediates with often unusual or unconventional reactivities. This tutorial review will systematically illustrate the reactivities of vinyl azides and describe recent breakthroughs in the development of new transformations that create N-heterocycles. PMID:25731154

  6. Emotional reactivity, functioning, and C-reactive protein alterations in remitted bipolar patients: Clinical relevance of a dimensional approach.

    PubMed

    Dargél, Aroldo A; Godin, Ophelia; Etain, Bruno; Hirakata, Vânia; Azorin, Jean-Michel; M'Bailara, Katia; Bellivier, Frank; Bougerol, Thierry; Kahn, Jean-Pierre; Passerieux, Christine; Aubin, Valerie; Courtet, Philippe; Leboyer, Marion; Henry, Chantal

    2017-08-01

    Inter-episode mood instability has increasingly been considered in bipolar disorder. This study aimed to investigate emotional reactivity as a major dimension for better characterizing remitted bipolar patients with subthreshold mood symptoms and functional status. This study also aimed to investigate whether high-sensitivity C-reactive protein, a marker of low-grade inflammation, could be a biological marker of emotional dysregulation in bipolar disorder (BD). Cross-sectional study of 613 subjects who met Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition criteria for BD recruited from the FondaMental Advanced Centers of Expertise in Bipolar Disorders cohort from 2009 to 2014. All patients had been in remission for at least 3 months before assessment. Patients were classified into three groups according to levels of emotional reactivity. Emotional reactivity was assessed by using the Multidimensional Assessment of Thymic States, and functional status was assessed by the Functioning Assessment Short Test. Clinical characteristics and blood sample were collected from all patients. In total, 415 (68%) patients had abnormal emotional reactivity. Independent of potential confounders, including age, gender and subthreshold mood symptoms, serum levels of high-sensitivity C-reactive protein were significantly higher in patients with emotional hyper-reactivity (median = 4.0 mg/L, interquartile range = 2.7-5.6), and with emotional hypo-reactivity (median = 3.0 mg/L, interquartile range = 1-4) compared with patients with normal emotional reactivity (median = 0.95 mg/L, interquartile range = 0.4-1.9, p < 0.001). Patients with emotional hyper-reactivity showed significant cognitive functioning impairment ( p < 0.001). Emotional reactivity appears to be a relevant dimension for better characterizing remitted bipolar patients with subthreshold mood symptoms. Levels of high-sensitivity C-reactive protein may be an

  7. Unsaturated platinum-rhenium cluster complexes. Synthesis, structures and reactivity.

    PubMed

    Adams, Richard D; Captain, Burjor; Smith, Mark D; Beddie, Chad; Hall, Michael B

    2007-05-09

    functional calculations confirm the hydride positions in the lowest energy structural isomers of 11 and 12 and suggest a mechanism for H2 addition to 11 that occurs on the Pt atom with the lower coordination number.

  8. Divergent synthesis and chemical reactivity of bicyclic lactone fragments of complex rearranged spongian diterpenes.

    PubMed

    Schnermann, Martin J; Beaudry, Christopher M; Genung, Nathan E; Canham, Stephen M; Untiedt, Nicholas L; Karanikolas, Breanne D W; Sütterlin, Christine; Overman, Larry E

    2011-11-02

    The synthesis and direct comparison of the chemical reactivity of the two highly oxidized bicyclic lactone fragments found in rearranged spongian diterpenes (8-substituted 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one and 6-substituted 7-acetoxy-2,8-dioxabicyclo[3.3.0]octan-3-one) are reported. Details of the first synthesis of the 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one ring system, including an examination of several possibilities for the key bridging cyclization reaction, are described. In addition, the first synthesis of 7-acetoxy-2,8-dioxabicyclo[3.3.0]octanones containing quaternary carbon substituents at C6 is disclosed. Aspects of the chemical reactivity and Golgi-modifying properties of these bicyclic lactone analogs of rearranged spongian diterpenes are also reported. Under both acidic and basic conditions, 8-substituted 2,7-dioxabicyclo[3.2.1]octanones are converted to 6-substituted-2,8-dioxabicyclo[3.3.0]octanones. Moreover, these dioxabicyclic lactones react with primary amines and lysine side chains of lysozyme to form substituted pyrroles, a conjugation that could be responsible for the unique biological properties of these compounds. These studies demonstrate that acetoxylation adjacent to the lactone carbonyl group, in either the bridged or fused series, is required to produce fragmented Golgi membranes in the pericentriolar region that is characteristic of macfarlandin E.

  9. Heavy Grignard Reagents: Synthesis, Physical and Structural Properties, Chemical Behavior, and Reactivity.

    PubMed

    Westerhausen, Matthias; Koch, Alexander; Görls, Helmar; Krieck, Sven

    2017-01-31

    The Grignard reaction offers a straight forward atom-economic synthesis of organomagnesium halides, which undergo redistribution reactions (Schlenk equilibrium) yielding diorganylmagnesium and magnesium dihalides. The homologous organocalcium complexes (heavy Grignard reagents) gained interest only quite recently owing to several reasons. The discrepancy between the inertness of this heavy alkaline earth metal and the enormous reactivity of its organometallics hampered a vast and timely development after the first investigation more than 100 years ago. In this overview the synthesis of organocalcium reagents is described as is the durability in ethereal solvents. Aryl-, alkenyl-, and alkylcalcium halides are prepared by direct synthesis. Characteristic structural features and NMR parameters are discussed. Ligand redistribution reactions can be performed by addition of potassium tert-butanolate to ethereal solutions of arylcalcium iodides yielding soluble diarylcalcium, whereas sparingly soluble potassium iodide and calcium bis(tert-butanolate) precipitate. Furthermore, reactivity studies with respect to metalation and addition to unsaturated organic compounds and metal-based Lewis acids, leading to the formation of heterobimetallic complexes, are presented.

  10. Divergent Synthesis and Chemical Reactivity of Bicyclic Lactone Fragments of Complex Rearranged Spongian Diterpenes

    PubMed Central

    Schnermann, Martin J.; Beaudry, Christopher M.; Genung, Nathan E.; Canham, Stephen M.; Untiedt, Nicholas L.; Karanikolas, Breanne D. W.; Sütterlin, Christine; Overman, Larry E.

    2011-01-01

    The synthesis and direct comparison of the chemical reactivity of the two highly oxidized bicyclic lactone fragments found in rearranged spongian diterpenes (8-substituted 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one and 6-substituted 7-acetoxy-2,8-dioxabicyclo[3.3.0]octan-3-one) are reported. Details of the first synthesis of the 6-acetoxy-2,7-dioxabicyclo[3.2.1]octan-3-one ring system, including an examination of several possibilities for the key bridging cyclization reaction, are described (Schemes 2–5). In addition, the first synthesis of 7-acetoxy-2,8-dioxabicyclo[3.3.0]octanones containing quaternary carbon substituents at C6 is disclosed (Scheme 6). Aspects of the chemical reactivity and Golgi-modifying properties of these bicyclic lactone analogs of rearranged spongian diterpenes are also reported. Under both acidic and basic conditions, 8-substituted 2,7-dioxabicyclo[3.2.1]octanones are converted to 6-substituted-2,8-dioxabicyclo[3.3.0]octanones. Moreover, these dioxabicyclic lactones react with primary amines and lysine side chains of lysozyme to form substituted pyrroles, a conjugation that could be responsible for the unique biological properties of these compounds. These studies demonstrate that acetoxylation adjacent to the lactone carbonyl group—in either the bridged or fused series—is required to produce fragmented Golgi membranes in the pericentriolar region that is characteristic of macfarlandin E. PMID:21988207

  11. Pyro-Synthesis of Functional Nanocrystals

    PubMed Central

    Gim, Jihyeon; Mathew, Vinod; Lim, Jinsub; Song, Jinju; Baek, Sora; Kang, Jungwon; Ahn, Docheon; Song, Sun-Ju; Yoon, Hyeonseok; Kim, Jaekook

    2012-01-01

    Despite nanomaterials with unique properties playing a vital role in scientific and technological advancements of various fields including chemical and electrochemical applications, the scope for exploration of nano-scale applications is still wide open. The intimate correlation between material properties and synthesis in combination with the urgency to enhance the empirical understanding of nanomaterials demand the evolution of new strategies to promising materials. Herein we introduce a rapid pyro-synthesis that produces highly crystalline functional nanomaterials under reaction times of a few seconds in open-air conditions. The versatile technique may facilitate the development of a variety of nanomaterials and, in particular, carbon-coated metal phosphates with appreciable physico-chemical properties benefiting energy storage applications. The present strategy may present opportunities to develop “design rules” not only to produce nanomaterials for various applications but also to realize cost-effective and simple nanomaterial production beyond lab-scale limitations. PMID:23230511

  12. Pyro-Synthesis of Functional Nanocrystals

    NASA Astrophysics Data System (ADS)

    Gim, Jihyeon; Mathew, Vinod; Lim, Jinsub; Song, Jinju; Baek, Sora; Kang, Jungwon; Ahn, Docheon; Song, Sun-Ju; Yoon, Hyeonseok; Kim, Jaekook

    2012-12-01

    Despite nanomaterials with unique properties playing a vital role in scientific and technological advancements of various fields including chemical and electrochemical applications, the scope for exploration of nano-scale applications is still wide open. The intimate correlation between material properties and synthesis in combination with the urgency to enhance the empirical understanding of nanomaterials demand the evolution of new strategies to promising materials. Herein we introduce a rapid pyro-synthesis that produces highly crystalline functional nanomaterials under reaction times of a few seconds in open-air conditions. The versatile technique may facilitate the development of a variety of nanomaterials and, in particular, carbon-coated metal phosphates with appreciable physico-chemical properties benefiting energy storage applications. The present strategy may present opportunities to develop ``design rules'' not only to produce nanomaterials for various applications but also to realize cost-effective and simple nanomaterial production beyond lab-scale limitations.

  13. Time resolved ion energy distribution functions of non-reactive and reactive high power impulse magnetron sputtering of titanium

    NASA Astrophysics Data System (ADS)

    Grosse, Katharina; Breilmann, Wolfgang; Maszl, Christian; Benedikt, Jan; von Keudell, Achim

    2016-09-01

    High power impulse magnetron sputtering (HiPIMS) is a technique for thin film deposition and can be operated in reactive and non-reactive mode. The growth rate of HiPIMS in non-reactive mode reduces to 30% compared to direct current magnetron sputtering (dcMS) at same average power. However, the quality of the coatings produced with HiPIMS is excellent which makes these plasmas highly appealing. In reactive mode target poisoning is occurring which changes the plasma dynamics. An advantage of reactive HiPIMS is that it can be operated hysteresis-free which can result in a higher growth rate compared to dcMS. In this work thin films are deposited by a HiPIMS plasma which is generated by short pulses of 100 μs with high power densities in the range of 1 kW/cm2. Ar and Ar/N2 admixtures are used as a working gas to sputter a 2'' titanium target. The particle transport is analysed with time resolved ion energy distribution functions which are measured by a mass spectrometer with a temporal resolution of 2 μs. Phase resolved optical emission spectroscopy is executed to investigate the particle dynamics of different species. The time and energy resolved particle fluxes in non-reactive and reactive mode are compared and implications on the sputter process are discussed.

  14. Reliability and reactivity of three new functional assessment measures.

    PubMed

    Matheson, Leonard N; Rogers, Lisa C; Kaskutas, Victoria; Dakos, Mark

    2002-01-01

    This study of the reliability of three new tests of work performance considered the effect of test reactivity on measured performance. The tests are components of an employment screening battery designed for placement of applicants in automotive assembly jobs. Statistical measures of reliability were compared with a simple measure of test reactivity in a sample of 51 healthy adults. The effect of test reactivity on employment selection decisions using various cut scores was studied. Test reactivity is found to be a significant threat to reliability that must be considered when skill-based performance tests are used on a serial basis. When intended for use on a serial basis, such tests should be studied for both reliability and reactivity. In addition to reporting traditional statistical indices of reliability, an index of the reactivity should be reported.

  15. In Situ Synthesis of FeAl Dense Coatings by Very Low Pressure Reactive Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Zhu, Lin; Zhang, Nannan; Zhang, Baicheng; Bolot, Rodolphe; Liao, Hanlin; Coddet, Christian

    2013-03-01

    With the purpose of elaborating high-quality FeAl coatings, a so-called very low pressure reactive plasma spray technique that combines very low pressure plasma spray and self-propagation high-temperature synthesis processes was used in the present study. A dense and homogeneous FeAl coating was thus successfully in situ synthesized by reactive plasma spraying of an Al/Fe2O3 composite powder under 1 mbar. The phase composition and microstructural features of the coating were characterized by XRD and SEM. Results indicated that the B2 ordered FeAl phase was synthesized, and the coating featured a dense and defect-free microstructure. The fracture mechanism of the coating remains mainly a brittle failure but the appearance of some dimples in local zones suggested some unexpected toughness.

  16. Tuning the Synthesis of Ternary Lead Chalcogenide Quantum Dots by Balancing Precursor Reactivity

    SciTech Connect

    Smith, Danielle K.; Luther, Joseph M; Semonin, Octavi Escala; Nozik, Arthur J; Beard, Matthew C

    2011-01-25

    We report the synthesis and characterization of composition-tunable ternary lead chalcogenide alloys PbSe{sub x}Te{sub 1-x}, PbS{sub x}Te{sub 1-x}, and PbS{sub x}Se{sub 1-x}. This work explores the relative reaction rates of chalcogenide precursors to produce alloyed quantum dots (QDs), and we find the highly reactive bis(trimethylsilyl) (TMS{sub 2})-based precursors allow for the homogeneous incorporation of anions. By varying the Pb to oleic acid ratio, we demonstrate size control of similar composition alloys. We find the resulting QDs are Pb-rich but the Pb/anion ratio is size- and composition-dependent in all alloyed QD as well as in PbSe, PbTe, and PbS QDs and is consistent with the reaction rates of the anion precursors. A more reactive anion precursor results in a lower Pb/anion ratio.

  17. Arginine deiminase modulates endothelial tip cells via excessive synthesis of reactive oxygen species.

    PubMed

    Zhuo, Wei; Song, Xiaomin; Zhou, Hao; Luo, Yongzhang

    2011-10-01

    ADI (arginine deiminase), an enzyme that hydrolyses arginine, has been reported as an anti-angiogenesis agent. However, its molecular mechanism is unclear. We have demonstrated for the first time that ADI modulates the angiogenic activity of endothelial tip cells. By arginine depletion, ADI disturbs actin filament in endothelial tip cells, causing disordered migratory direction and decreased migration ability. Furthermore, ADI induces excessive synthesis of ROS (reactive oxygen species), and activates caspase 8-, but not caspase 9-, dependent apoptosis in endothelial cells. These findings provide a novel mechanism by which ADI inhibits tumour angiogenesis through modulating endothelial tip cells.

  18. Synthesis, structure and reactivity of rare-earth metal complexes containing anionic phosphorus ligands.

    PubMed

    Li, Tianshu; Kaercher, Sabrina; Roesky, Peter W

    2014-01-07

    A comprehensive review of structurally characterized rare-earth metal complexes containing anionic phosphorus ligands is presented. Since rare-earth elements form hard ions and phosphorus is considered as a soft ligand, the rare-earth metal phosphorus coordination is regarded as a less favorite combination. Three classes of phosphorus ligands, (1) the monoanionic organophosphide ligands (PR2(-)) bearing one negative charge on the phosphorus atom; (2) the dianionic phosphinidene (PR(2-)) and P(3-) ligands; and (3) the pure inorganic polyphosphide ligands (Pn(x-)), are included here. Particular attention has been paid to the synthesis, structure, and reactivity of the rare-earth metal phosphides.

  19. Synthesis, Characterization, and Reactivity Studies of Iron Complexes Supported by the Redox-Active [ONO] Ligand

    NASA Astrophysics Data System (ADS)

    Wong, Janice Lin

    The work reported herein primarily focuses on the development of new platforms for multi-electron reactivity using iron complexes supported by a redox-active pincer-type ligand. This dissertation details the synthesis, characterization, and reactivity of iron complexes coordinated to the redox-active [ONO] ([ONO]H3 = bis(3,5-di-tert-butyl-2-phenol)amine) ligand. Chapter 1 provides a general background on ligand-centered and metal-centered redox reactivity. Specifically, the characteristics of redox-active ligands and their ability to promote multi-electron reactivity at redox-inert metal centers is presented. In addition, iron-catalyzed organic transformations in which the metal center undergoes redox changes is also discussed. Finally, ligand-enabled redox reactions mediated by iron complexes containing redox-active ligands is described. Chapter 2 reports on the complexation of bis(3,5-di-tert-butyl-2-phenoxy)amine, [ONHO], and the redox-active [ONO] ligands by iron centers to afford a new family of iron complexes. Characterizations of each compound through a battery of analytical techniques reveal the oxidation states of the metal center and ligand. Furthermore, the electronic properties of each complex were investigated in order to evaluate their potential to facilitate multi-electron reactivity. Chapter 3 details the reactivity of the [ONO]Fe platform. Metathesis reactions are conducted with [ONOq]FeIIIX 2 (X = Cl, N[SiMe3]2) complexes, demonstrating the capability of the fully-oxidized [ONOq]1-- to act as a two-electron acceptor to generate the fully reduced [ONO cat]3-- that is coordinated to an iron(III) center. Similarly, oxidation of [ONOcat]FeIII(py) 3 (py = pyridine) using dihalogens result in two-electron oxidations of the tridentate ligand while the metal oxidation state remains the same. These redox reactions showcase the ability of the [ONO] ligand platform to undergo reversible two-electron oxidation state changes, allowing multi-electron reactivity

  20. Reactive Oxygen and Nitrogen Species and Functional Adaptation of the Placenta

    PubMed Central

    Myatt, Leslie

    2009-01-01

    The placenta regulates fetal growth and development via transport of nutrients and gases, and synthesis and secretion of steroid and peptide hormones. These functions are determined by vascular development and blood flow and by growth and differentiation of the trophoblast, which contains receptors, transporters and enzymes. The placenta generates reactive oxygen species which may contribute to the oxidative stress seen even in normal pregnancy but this is increased in pregnancies complicated by preeclampsia, IUGR and pregestational diabetes where oxidative and nitrative stress have been clearly documented. Nitrative stress is the covalent modification of proteins and DNA by peroxynitrite formed by the interaction of superoxide and nitric oxide. We have demonstrated nitrative stress by localizing nitrotyrosine residues in these placentas and found increased expression of NADPH oxidase (NOX) enzyme isoforms 1 and 5 as a potential source of superoxide generation. The presence of nitrative stress was associated with diminished vascular reactivity of the fetal placental circulation, a situation that could be reproduced by treatment with peroxynitrite in vitro. We find many nitrated proteins in the placenta, including p38 MAP kinase which has a role in development of the villous vasculature. Nitration of p38 MAPK was increased in the preeclamptic placenta and associated with loss of catalytic activity. We hypothesize that nitration of proteins in the placenta including receptors, transporters, enzymes and structural proteins can alter protein and placental function and this influences fetal growth and development. Increasing nitrative stress but a decrease in oxidative stress, measured as protein carbonylation, is found in the placenta with increasing BMI. Formation of peroxynitrite may then consume superoxide, decreasing nitrative stress. As protein carbonylation is a covalent modification at Lys, Arg, Pro and Thr residues the switch from carbonylation to nitration at

  1. Association between functional iron deficiency and reactive thrombocytosis in hospitalised patients: a case-control study.

    PubMed

    Nicola, H; Ho, K M; Cordingley, F

    2016-11-01

    The association of deficiency in total body iron with an increased risk of reactive thrombocytosis is well known, but whether 'functional iron deficiency' is also associated with reactive thrombocytosis is unknown. This retrospective case-control study assessed the relationships between functional iron deficiency, reactive thrombocytosis and risk of thromboembolism. A total of 150 patients with reactive thrombocytosis (platelet count >400 x 10(9)/l) and 343 controls (platelet count <400 x 10(9)/l) were selected from the hospital laboratory database system. Patients with haematological disease or recent chemotherapy were excluded. Reactive thrombocytosis, infection, and an elevated C-reactive protein (CRP) concentration were all significantly more common in patients with functional iron deficiency than in those without functional iron deficiency (all P <0.01). After adjusting for infection and CRP concentration, functional iron deficiency was the only marker of iron status significantly associated with reactive thrombocytosis (odds ratio 1.66, 95% confidence interval 1.10-2.75; P=0.048). Thromboembolic events occurred in 32 patients (6.6%). This was not significantly associated with functional iron deficiency. Our results suggest that in patients without haematological malignancy or recent chemotherapy there might be a link between functional iron deficiency and reactive thrombocytosis. Whether treating patients with functional iron deficiency with intravenous iron corrects reactive thrombocytosis without inducing infection remains uncertain, but merits further investigation.

  2. Impact of C-reactive protein (CRP) on surfactant function

    SciTech Connect

    Li, J.J.; Sanders, R.L.; McAdam, K.P.; Hales, C.A.; Thompson, B.T.; Gelfand, J.A.; Burke, J.F. )

    1989-12-01

    Plasma levels of the acute-phase reactant, C-reactive protein (CRP), increase up to one thousand-fold as a result of trauma or inflammation. CRP binds to phosphorylcholine (PC) in a calcium-ion dependent manner. The structural homology between PC and the major phospholipid component of surfactant, dipalmitoyl phosphatidylcholine (DPPC), led to the present study in which we examined if CRP levels might be increased in patients with adult respiratory distress syndrome (ARDS), and subsequently interfere with surfactant function. Our results showed that CRP levels in the bronchoalveolar fluid (BALF) was increased in patients with ARDS (97.8 +/- 84.2 micrograms/mg total protein vs. 4.04 +/- 2.2 micrograms/mg total protein in normals). Our results show that CRP binds to liposomes containing DPPC and phosphatidylglycerol (PG). As a result of this interaction, CRP inhibits the surface activity of a PG-DPPC mixture when tested with a Wilhelmy surfactometer or with the Enhorning pulsating bubble apparatus. Furthermore, the surface activity of a clinically used surfactant replacement, Surfactant TA (2 mg/ml), was also severely impaired by CRP in a dose-dependent manner (doses used ranging from 24.5 to 1,175 micrograms/ml). In contrast, human serum albumin (HSA) at 500 and 900 micrograms/ml had no inhibitory effect on Surfactant TA surface activity. These results suggest that CRP, although not an initiating insult in ARDS, may contribute to the subsequent abnormalities of surfactant function and thus the pathogenesis of the pulmonary dysfunction seen in ARDS.

  3. Filtered density function approach for reactive transport in groundwater

    NASA Astrophysics Data System (ADS)

    Suciu, Nicolae; Schüler, Lennart; Attinger, Sabine; Knabner, Peter

    2016-04-01

    Spatial filtering may be used in coarse-grained simulations (CGS) of reactive transport in groundwater, similar to the large eddy simulations (LES) in turbulence. The filtered density function (FDF), stochastically equivalent to a probability density function (PDF), provides a statistical description of the sub-grid, unresolved, variability of the concentration field. Besides closing the chemical source terms in the transport equation for the mean concentration, like in LES-FDF methods, the CGS-FDF approach aims at quantifying the uncertainty over the whole hierarchy of heterogeneity scales exhibited by natural porous media. Practically, that means estimating concentration PDFs on coarse grids, at affordable computational costs. To cope with the high dimensionality of the problem in case of multi-component reactive transport and to reduce the numerical diffusion, FDF equations are solved by particle methods. But, while trajectories of computational particles are modeled as stochastic processes indexed by time, the concentration's heterogeneity is modeled as a random field, with multi-dimensional, spatio-temporal sets of indices. To overcome this conceptual inconsistency, we consider FDFs/PDFs of random species concentrations weighted by conserved scalars and we show that their evolution equations can be formulated as Fokker-Planck equations describing stochastically equivalent processes in concentration-position spaces. Numerical solutions can then be approximated by the density in the concentration-position space of an ensemble of computational particles governed by the associated Itô equations. Instead of sequential particle methods we use a global random walk (GRW) algorithm, which is stable, free of numerical diffusion, and practically insensitive to the increase of the number of particles. We illustrate the general FDF approach and the GRW numerical solution for a reduced complexity problem consisting of the transport of a single scalar in groundwater

  4. Synthesis of functional oxides through plasma spraying

    NASA Astrophysics Data System (ADS)

    Guo, Xianzhong

    Thermal spray coatings have become an important part of modern industry, offering customized surface properties for a variety of industrial applications, e.g. thermal barrier coatings, wear resistant coatings, erosion resistant coatings and functional coatings. Although the usage of thermal spray coatings has increased dramatically, the scientific research of these coatings has lagged behind. Good understanding of thermal spray processes can provide the optimistic combination of operation parameters to obtain high quality of coating, improve service life of the product, and lower cost of the system. The research presented in this dissertation focuses on the synthesis of functional oxide coatings through plasma spraying techniques. The materials studied in this research are: yttrium aluminum garnet (YAG) which can be the thermal barrier coating and environmental barrier coating; doped YAG as phosphor; yttrium iron garnet (YIG) applied in telecommunication and data storage; aluminum substituted YIG for biomedical applications; and zirconium substituted yttrium titanate pyrochlore in developing solid oxide fuel cells (SOFCs). The synthesis processes, phase formation, microstructure, and physical properties of above materials have been investigated in a comprehensive and integrated way. The precursor powders or solutions were prepared via different chemical routes. The experiments suggest that formation of phase-pure oxides occurs through different phase evolution pathways and depending on the reaction conditions. Chemically derived precursors and/or powders were used as feedstock in plasma spray to form functional oxide coatings. Due to its rapid heating and cooling features, plasma spraying techniques provide a novel opportunity for functional oxides to transfer from amorphous into crystallized structure at a relatively low temperature in a single step. The properties of assprayed and post-heated coatings strongly depend on their microstructure and phase content.

  5. The regulation of superoxide generation and nitric oxide synthesis by C-reactive protein.

    PubMed Central

    Ratnam, S; Mookerjea, S

    1998-01-01

    Activated macrophages utilize both reactive oxygen intermediates and reactive oxynitrogen intermediates for defence against microbes. However, simultaneous generation of superoxide (O- 2;) and nitric oxide (NO) could be harmful to host cells due to the production of peroxynitrite, nitrogen dioxide and hydroxyl radicals. Therefore, the regulation of the production of these molecules is critical to host survival. During periods of inflammation or infection, the level of serum C-reactive protein (CRP) increases in many species. Human and rat CRP have been shown to bind and interact with phagocytic cells. Since many of the interactions of CRP involve the binding to the phosphocholine ligand, we studied the role of CRP in O- 2; and NO generation through the modulation of phosphatidylcholine (PC) metabolism in macrophages. This study has shown that, while rat CRP inhibited phorbol myristate acetate- (PMA) induced release of O- 2; by rat macrophages, CRP-treated macrophages released NO in a time- and dose-dependent manner. CRP increased inducible nitric oxide synthase (iNOS) enzyme as well as iNOS mRNA levels in rat macrophages. Tricyclodecan-9-yl-xanthogenate (D609), an inhibitor to PC phospholipase C (PC-PLC), suppressed iNOS induction but enhanced PMA-induced release of O- 2;. These data indicate that an increased level of CRP during periods of inflammation may result in differential regulation of macrophage NADPH oxidase and iNOS activity. Increased hepatic synthesis of CRP may contribute to the mechanism by which phagocytic cells avoid simultaneous O- 2; and NO synthesis, and this could possibly be mediated through the regulation of PC-PLC. Images Figure 4 Figure 5 PMID:9767445

  6. Synthesis and postmodification of functionally relevant organically modified silica particles

    NASA Astrophysics Data System (ADS)

    Brozek, Eric

    This thesis describes the synthesis and properties of organically modified silica (ORMOSIL) particles with possible applications in the field of drug delivery. Nanoparticle drug delivery methods take advantage of the unique physical properties of nanoscale architecture to deliver a large payload of drug to a targeted site. They are highly porous, contain many organic functionalities for covalent attachment, and their surfaces can be functionalized. A particle-based approach allows for the delivery of a large and localized payload in a single package. Initial study focused on the generation of submicron organically modified silica particles containing boron. This involved the synthesis of vinyl-enriched silica particles and the postmodification of the vinyl functionalities throughout the particle body. Hydroboration and bromination of the vinyl functionalities showed for the first time that the organic functionalities of ORMOSIL particles could be significantly modified. Next, new organically modified silica particle types were developed. These new particle types incorporated unique organic functionalities that may undergo additional functionalization. Organic functionalities included alkenyl-, cyano-, mercapto-, and isocyanto- throughout the particle body. The different organic functionalities were then modified to demonstrate their reactivity. Finally, a particle containing nuclei suitable for neutron capture therapy, a fluorescent tag, and targeting ligand was synthesized. Boron was the active nuclei, fluorescein was the fluorescent label, useful for in vitro studies, and folic acid is a broad field targeting ligand, useful in targeting a variety of cancer types. The particle containing the three unique motifs underwent early stages of in vitro studies against the OVCAR-3 cell line. This thesis has considerably advanced the field of ORMOSIL chemistry through the development and modification of new ORMOSIL products. While initial efforts were geared toward the

  7. Synthesis and reactivity of compounds containing ruthenium-carbon, -nitrogen, and -oxygen bonds

    SciTech Connect

    Hartwig, J.F.

    1990-12-01

    The products and mechanisms of the thermal reactions of several complexes of the general structure (PMe{sub 3}){sub 4}Ru(X)(Y) and (DMPM){sub 2}Ru(X)(Y) where X and Y are hydride, aryl, and benzyl groups, have been investigated. The mechanism of decomposition depends critically on the structure of the complex and the medium in which the thermolysis is carried out. The alkyl hydride complexes are do not react with alkane solvent, but undergo C-H activation processes with aromatic solvents by several different mechanisms. Thermolysis of (PMe{sub 3}){sub 4}Ru(Ph)(Me) or (PMe{sub 3}){sub 4}Ru(Ph){sub 2} leads to the ruthenium benzyne complex (PMe{sub 3}){sub 4}Ru({eta}{sup 2}-C{sub 6}H{sub 4}) (1) by a mechanism which involves reversible dissociation of phosphine. In many ways its chemistry is analogous to that of early rather than late organo transition metal complexes. The synthesis, structure, variable temperature NMR spectroscopy and reactivity of ruthenium complexes containing aryloxide or arylamide ligands are reported. These complexes undergo cleavage of a P-C bond in coordinated trimethylphosphine, insertion of CO and CO{sub 2} and hydrogenolysis. Mechanistic studies on these reactions are described. The generation of a series of reactive ruthenium complexes of the general formula (PMe{sub 3}){sub 4}Ru(R)(enolate) is reported. Most of these enolates have been shown to bind to the ruthenium center through the oxygen atom. Two of the enolate complexes 8 and 9 exist in equilibrium between the O- and C-bound forms. The reactions of these compounds are reported, including reactions to form oxygen-containing metallacycles. The structure and reactivity of these ruthenium metallacycles is reported, including their thermal chemistry and reactivity toward protic acids, electrophiles, carbon monoxide, hydrogen and trimethylsilane. 243 refs., 10 tabs.

  8. Synthesis and Functions of Jasmonates in Maize

    PubMed Central

    Borrego, Eli J.; Kolomiets, Michael V.

    2016-01-01

    Of the over 600 oxylipins present in all plants, the phytohormone jasmonic acid (JA) remains the best understood in terms of its biosynthesis, function and signaling. Much like their eicosanoid analogues in mammalian system, evidence is growing for the role of the other oxylipins in diverse physiological processes. JA serves as the model plant oxylipin species and regulates defense and development. For several decades, the biology of JA has been characterized in a few dicot species, yet the function of JA in monocots has only recently begun to be elucidated. In this work, the synthesis and function of JA in maize is presented from the perspective of oxylipin biology. The maize genes responsible for catalyzing the reactions in the JA biosynthesis are clarified and described. Recent studies into the function of JA in maize defense against insect herbivory, pathogens and its role in growth and development are highlighted. Additionally, a list of JA-responsive genes is presented for use as biological markers for improving future investigations into JA signaling in maize. PMID:27916835

  9. Synthesis and characterization of aryl phosphine oxide containing thermoplastic polyimides and thermosetting polyimides with controlled reactivity

    NASA Astrophysics Data System (ADS)

    Zhuang, Hong

    1998-11-01

    Phosphorus containing monomers, bis(3-aminophenyl)methyl phosphine oxide (m-DAMPO) and bis(3-aminophenyl)phenyl phosphine oxide (m-DAPPO), were synthesized and incorporated into a thermoplastic poly(arylene ether imide) based upon 2,2sp'-bis (4-(3,4-dicarboxyphenoxy)phenyl) propane dianhydride and 1,3-phenylene diamine, in order to study their influence on flame resistance and other properties. DAMPO or DAPPO were quantitatively incorporated in concentrations of 25, 50, 75 and 100 mole percent, using the "one pot" ester-acid method. The number average molecular weights of the prepared materials were controlled to 20,000g/mol by off-setting the stoichiometry and endcapping with phthalic anhydride. This strategy enabled one to distinguish the effects of the phosphine oxide incorporation from the influence of molecular weight. The resulting copolymers demonstrated a significant increase in char yield as a function of the phosphine oxide content, thus suggesting improved fire resistance. Glass transition temperatures similar to the control were determined by DSC analysis. Analysis of the mechanical behavior of the DAMPO system at room temperature showed that tensile strength and elongation at failure values were comparable to the control system, while the DAPPO containing copolymers were surprisingly brittle. The influence of the reactive endgroup on the synthesis, cure behavior and network properties of thermosetting polyetherimides was investigated. Reactive phenylacetylene, acetylene and maleimide terminated poly(ether imide) oligomers were prepared and characterized. Optimal reaction conditions were established to produce fully endcapped oligomers with imidized structures and controlled molecular weight. The phenylacetylene endcapped system was synthesized by a conventional ester-acid method. The acetylene endcapped system was prepared via modified ester-acid method and the maleimide endcapped system was fabricated utilizing an amic-acid route. It was determined

  10. Biogenic nanoparticulate UO 2: Synthesis, characterization, and factors affecting surface reactivity

    NASA Astrophysics Data System (ADS)

    Singer, David M.; Farges, François; Brown, Gordon E., Jr.

    2009-06-01

    The surface reactivity of biogenic, nanoparticulate UO 2 with respect to sorption of aqueous Zn(II) and particle annealing is different from that of bulk uraninite because of the presence of surface-associated organic matter on the biogenic UO 2. Synthesis of biogenic UO 2 was accomplished by reduction of aqueous uranyl ions, UO22+ by Shewanella putrefaciens CN32, and the resulting nanoparticles were washed using one of two protocols: (1) to remove surface-associated organic matter and soluble uranyl species (NAUO2), or (2) to remove only soluble uranyl species (BIUO2). A suite of bulk and surface characterization techniques was used to examine bulk and biogenic, nanoparticulate UO 2 as a function of particle size and surface-associated organic matter. The N 2-BET surface areas of the two biogenic UO 2 samples following the washing procedures are 128.63 m 2 g -1 (NAUO2) and 92.56 m 2 g -1 (BIUO2), and the average particle sizes range from 5-10 nm based on TEM imaging. Electrophoretic mobility measurements indicate that the surface charge behavior of biogenic, nanoparticulate UO 2 (both NAUO2 and BIUO2) over the pH range 3-9 is the same as that of bulk. The U L III-edge EXAFS spectra for biogenic UO 2 (both NAUO2 and BIUO2) were best fit with half the number of second-shell uranium neighbors compared to bulk uraninite, and no oxygen neighbors were detected beyond the first shell around U(IV) in the biogenic UO 2. At pH 7, sorption of Zn(II) onto both bulk uraninite and biogenic, nanoparticulate UO 2 is independent of electrolyte concentration, suggesting that Zn(II) sorption complexes are dominantly inner-sphere. The maximum surface area-normalized Zn(II) sorption loadings for the three substrates were 3.00 ± 0.20 μmol m -2 UO 2 (bulk uraninite), 2.34 ± 0.12 μmol m -2 UO 2 (NAUO2), and 2.57 ± 0.10 μmol m -2 UO 2 (BIUO2). Fits of Zn K-edge EXAFS spectra for biogenic, nanoparticulate UO 2 indicate that Zn(II) sorption is dependent on the washing protocol. Zn

  11. Synthesis of functional materials in combustion reactions

    SciTech Connect

    Zhuravlev, V. D. Bamburov, V. G.; Ermakova, L. V.; Lobachevskaya, N. I.

    2015-12-15

    The conditions for obtaining oxide compounds in combustion reactions of nitrates of metals with organic chelating–reducing agents such as amino acids, urea, and polyvinyl alcohol are reviewed. Changing the nature of internal fuels and the reducing agent-to-oxidizing agent ratio makes possible to modify the thermal regime of the process, fractal dimensionality, morphology, and dispersion of synthesized functional materials. This method can be used to synthesize simple and complex oxides, composites, and metal powders, as well as ceramics and coatings. The possibilities of synthesis in combustion reactions are illustrated by examples of αand γ-Al{sub 2}O{sub 3}, YSZ composites, uranium oxides, nickel powder, NiO and NiO: YSZ composite, TiO{sub 2}, and manganites, cobaltites, and aluminates of rare earth elements.

  12. Synthesis of functional materials in combustion reactions

    NASA Astrophysics Data System (ADS)

    Zhuravlev, V. D.; Bamburov, V. G.; Ermakova, L. V.; Lobachevskaya, N. I.

    2015-12-01

    The conditions for obtaining oxide compounds in combustion reactions of nitrates of metals with organic chelating-reducing agents such as amino acids, urea, and polyvinyl alcohol are reviewed. Changing the nature of internal fuels and the reducing agent-to-oxidizing agent ratio makes possible to modify the thermal regime of the process, fractal dimensionality, morphology, and dispersion of synthesized functional materials. This method can be used to synthesize simple and complex oxides, composites, and metal powders, as well as ceramics and coatings. The possibilities of synthesis in combustion reactions are illustrated by examples of αand γ-Al2O3, YSZ composites, uranium oxides, nickel powder, NiO and NiO: YSZ composite, TiO2, and manganites, cobaltites, and aluminates of rare earth elements.

  13. Catalytic performance of functionalized IRMOF-3 for the synthesis of glycerol carbonate from glycerol and urea.

    PubMed

    Lee, Sun-Do; Park, Gyung-Ah; Kim, Dong-Woo; Park, Dae-Won

    2014-06-01

    A functionalized isoreticular metal organic framework material, F-IRMOF-3, having a quaternary ammonium group was prepared by fast precipitation and solvothermal method. The synthesized MOFs exhibited good catalytic performance in the synthesis of glycerol carbonate (GC) from glycerol and urea. F-IRMOF-3 having a larger alkyl chain structure and a more nucleophilic counter anion than the synthesized congeners, exhibited better reactivity in the synthesis of GC. The introduction of a ZnO defect into the F-IRMOF-3 structure by fast precipitation was more advantageous for the glycerolysis of urea than the conventional solvothermal method because of the incorporation of acid-base bifunctional active sites by the former method. The effects of reaction parameters such as temperature, reaction time, catalyst loading, and degree of vacuum on the reactivity were also investigated. The F-IRMOF-3 catalyst can be easily recovered and reused without considerable loss of its initial activity.

  14. Synthesis and Reactivity of a Bio-inspired Dithiolene Ligand and its Mo Oxo Complex.

    PubMed

    Porcher, Jean-Philippe; Fogeron, Thibault; Gomez-Mingot, Maria; Chamoreau, Lise-Marie; Li, Yun; Fontecave, Marc

    2016-03-18

    An original synthesis of the fused pyranoquinoxaline dithiolene ligand qpdt(2-) is discussed in detail. The most intriguing step is the introduction of the dithiolene moiety by Pd-catalyzed carbon-sulfur coupling. The corresponding Mo(IV)O complex (Bu4N)2 [MoO(qpdt)2] (2) underwent reversible protonation in a strongly acidic medium and remained stable under anaerobic conditions. Besides, 2 was found to be very sensitive towards oxygen, as upon oxidation it formed a planar dithiin derivative. Moreover, the qpdt(2-) ligand in the presence of [MoCl4 (tBuNC)2] formed a tetracyclic structure. The products resulting from the unique reactivity of qpdt(2-) were characterized by X-ray diffraction, mass spectrometry, NMR spectroscopy, UV/Vis spectroscopy, and electrochemistry. Plausible mechanisms for the formation of these products are also proposed.

  15. Synthesis and Characterization of Reactive Powder Concrete for its Application on Thermal Insulation Panels

    NASA Astrophysics Data System (ADS)

    Chozas, V.; Larraza, Í.; Vera-Agullo, J.; Williams-Portal, N.; Mueller, U.; Da Silva, N.; Flansbjer, M.

    2015-11-01

    This paper describes the synthesis and characterization of a set of textile reinforced reactive powder concrete (RPC) mixes that have been prepared in the framework of the SESBE project which aims to develop facade panels for the building envelope. In order to reduce the environmental impact, high concentration of type I and II mineral additions were added to the mixtures (up to 40% of cement replacement). The mechanical properties of the materials were analysed showing high values of compression strength thus indicating no disadvantages in the compression mechanical performance (∼140 MPa) and modulus of elasticity. In order to enable the use of these materials in building applications, textile reinforcement was introduced by incorporating layers of carbon fibre grids into the RPC matrix. The flexural performance of these samples was analysed showing high strength values and suitability for their further utilization.

  16. Peptide template effects on the synthesis and reactivity of metal nanoparticle networks

    NASA Astrophysics Data System (ADS)

    Bhandari, Rohit

    A bio-templated approach for the synthesis of multiple inorganic materials has been presented that correlates with the role of a 3-dimensional peptide template in controlling the overall reactivity of the fabricated materials for a variety of chemical reactions. The role of self-assembling R5 peptide for the formation of metallic nanoparticles including Pd, Au and Pt has been described. The materials were fully characterized using UV-vis spectroscopy, dynamic light scattering analysis, transmission electron microscopy and powder-X ray diffraction analysis. Also, the materials were employed as efficient catalysts for the Stille coupling reaction, 4-nitrophenol reduction as well as olefin hydrogenation reactions. These results are important as these template-based materials could potentially serve as candidates for a variety of applications ranging from bio- sensing tocatalysis to energy production.

  17. Synthesis and reactivity of palladium(II) fluoride complexes containing nitrogen-donor ligands.

    PubMed

    Ball, Nicholas D; Kampf, Jeff W; Sanford, Melanie S

    2010-01-14

    This article describes the synthesis, characterization, and reactivity of palladium(II) fluoride complexes containing sp(2) and sp(3) nitrogen-containing supporting ligands. Both cis and trans complexes of general structure (N)(N')Pd(II)(R)(F) (R = Ar or CH(3)) as well as cis-(N)(2)Pd(II)(F)(2) are reported. Crystallographic characterization of these molecules has allowed structural comparisons to related phosphine-ligated species. Furthermore, these studies have revealed that nitrogen-donor ligands support some of the longest and the shortest Pd-F bonds reported to date. The thermal decomposition of (N)(N')Pd(II)(R)(F) has also been examined, and no products of C-F bond-forming reductive elimination were obtained in any case.

  18. Lewis Acid Zeolites for Biomass Conversion: Perspectives and Challenges on Reactivity, Synthesis, and Stability.

    PubMed

    Luo, Helen Y; Lewis, Jennifer D; Román-Leshkov, Yuriy

    2016-06-07

    Zeolites containing Sn, Ti, Zr, Hf, Nb, or Ta heteroatoms are versatile catalysts for the activation and conversion of oxygenated molecules owing to the unique Lewis acid character of their tetrahedral metal sites. Through fluoride-mediated synthesis, hydrophobic Lewis acid zeolites can behave as water-tolerant catalysts, which has resulted in a recent surge of experimental and computational studies in the field of biomass conversion. However, many open questions still surround these materials, especially relating to the nature of their active sites. This lack of fundamental understanding is exemplified by the many dissonant results that have been described in recent literature reports. In this review, we use a molecular-based approach to provide insight into the relationship between the structure of the metal center and its reactivity toward different substrates, with the ultimate goal of providing a robust framework to understand the properties that have the strongest influence on catalytic performance for the conversion of oxygenates.

  19. Synthesis of novel amorphous calcium carbonate by sono atomization for reactive mixing.

    PubMed

    Kojima, Yoshiyuki; Kanai, Makoto; Nishimiya, Nobuyuki

    2012-03-01

    Droplets of several micrometers in size can be formed in aqueous solution by atomization under ultrasonic irradiation at 2 MHz. This phenomenon, known as atomization, is capable of forming fine droplets for use as a reaction field. This synthetic method is called SARM (sono atomization for reactive mixing). This paper reports on the synthesis of a novel amorphous calcium carbonate formed by SARM. The amorphous calcium carbonate, obtained at a solution concentration of 0.8 mol/dm(3), had a specific surface area of 65 m(2)/g and a composition of CaCO(3)•0.5H(2)O as determined using thermogravimetric/differential thermal analysis (TG-DTA). Because the ACC had a lower hydrate composition than conventional amorphous calcium carbonate (ACC), the ACC synthesized in this paper was very stable at room temperature. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

  20. Synthesis of ternary metal nitride nanoparticles using mesoporous carbon nitride as reactive template.

    PubMed

    Fischer, Anna; Müller, Jens Oliver; Antonietti, Markus; Thomas, Arne

    2008-12-23

    Mesoporous graphitic carbon nitride was used as both a nanoreactor and a reactant for the synthesis of ternary metal nitride nanoparticles. By infiltration of a mixture of two metal precursors into mesoporous carbon nitride, the pores act first as a nanoconfinement, generating amorphous mixed oxide nanoparticles. During heating and decomposition, the carbon nitride second acts as reactant or, more precisely, as a nitrogen source, which converts the preformed mixed oxide nanoparticles into the corresponding nitride (reactive templating). Using this approach, ternary metal nitride particles with diameters smaller 10 nm composed of aluminum gallium nitride (Al-Ga-N) and titanium vanadium nitride (Ti-V-N) were synthesized. Due to the confinement effect of the carbon nitride matrix, the composition of the resulting metal nitride can be easily adjusted by changing the concentration of the preceding precursor solution. Thus, ternary metal nitride nanoparticles with continuously adjustable metal composition can be produced.

  1. Synthesis of functional poly(disubstituted acetylene)s through the post-polymerization modification route.

    PubMed

    Gao, Yuan; Wang, Xiao; Sun, Jing Zhi; Tang, Ben Zhong

    2015-04-01

    We report the recent progress in the preparation of functional poly(disubstituted acetylene)s (PDSAs) through post-polymerization modification routes. The metathesis polymerization of disubstituted acetylene monomers activated by Mo/W-Sn complex catalysts, which do not tolerate highly polar functionalities, was assumed to be a key step in the polymer synthetic procedures. We and other groups have explored several approaches to prepare PDSAs with latent reactive functionalities, which are inactive to Mo/W-Sn complex catalysts but can be used as highly reactive sites for post-polymerization modification. Click chemistry, Michael-type addition reactions, the use of activated esters and other strategies are demonstrated by recently published examples. These works indicate that post-polymerization modification is an efficient route to the synthesis of various functional PDSAs.

  2. Translating Nature's Library: The Bryostatins and Function-Oriented Synthesis

    PubMed Central

    Wender, Paul A.; Loy, Brian A.; Schrier, Adam J.

    2012-01-01

    We review in part our computational, design, synthesis, and biological studies on a remarkable class of compounds and their designed analogs that have led to preclinical candidates for the treatment of cancer, a first-in-class approach to Alzheimer's disease, and a promising strategy to eradicate HIV/AIDS. Because these leads target, in part, protein kinase C (PKC) isozymes, they have therapeutic potential even beyond this striking set of therapeutic indications. This program has given rise to new synthetic methodology and represents an increasingly important direction of synthesis focused on achieving function through synthesis-informed design (function-oriented synthesis). PMID:22661768

  3. Design and Synthesis of Bifunctional Oxime Reactivators of OP- inhibited Cholinesterase

    DTIC Science & Technology

    2013-08-01

    oxalic acid and reflux for 15 minutes, after which the solvent was removed by reduced pressure. To the residue was added THF and Dimethyl sulfate (6.42...to enhance the kinetic rate of oxime reactivators through participation in general acid catalysis. Three general classes of compounds have been...2- pyridinium oximes that contains amine or similar functionality tethered to the 4-position that could act in general acid catalysis. General

  4. Synthesis of Some "Cobaloxime" Derivatives: A Demonstration of "Umpolung" in the Reactivity of an Organometallic Complex

    NASA Astrophysics Data System (ADS)

    Jameson, Donald L.; Grzybowski, Joseph J.; Hammels, Deb E.; Castellano, Ronald K.; Hoke, Molly E.; Freed, Kimberly; Basquill, Sean; Mendel, Angela; Shoemaker, William J.

    1998-04-01

    This article describes a four-reaction sequence for the synthesis of two organometallic "cobaloxime" derivatives. The concept of "Umpolung" or reversal of reactivity is demonstrated in the preparation of complexes. The complex Co(dmgH)2(4-t-BuPy)Et is formed by the reaction of a cobalt (I) intermediate (cobalt in the role of nucleophile) with ethyl iodide. The complex Co(dmgH)2(4-t-BuPy)Ph is formed by the reaction of PhMgBr with a cobalt (III) intermediate (cobalt in the role of electrophile). All the products contain cobalt in the diamagnetic +3 oxidation state and are readily characterized by proton and carbon NMR. The four reaction sequence may be completed in two 4-hour lab periods. Cobaloximes are well known as model complexes for Vitamin B-12 and the experiment exposes students to aspects of classical coordination chemistry, organometallic chemistry and bioinorganic chemistry. The experiment also illustrates an important reactivity parallel between organic and organometallic chemistry.

  5. Hyperbranched polyphosphates: synthesis, functionalization and biomedical applications.

    PubMed

    Liu, Jinyao; Huang, Wei; Pang, Yan; Yan, Deyue

    2015-06-21

    Hyperbranched polyphosphates (HBPPs) are newly emerged polymeric biomaterials with repeating phosphate bonds in a highly branched framework over the past 5 years. Due to the integration of the advantages of both hyperbranched polymers and polyphosphates, HBPPs are versatile in chemical structure, flexible in physicochemical properties, water soluble, biocompatible and biodegradable in biological features. On the basis of their excellent water solubility, biocompatibility, biodegradability and potential functionalization as well as their simple preparation in one-pot synthesis, HBPPs have fascinating biomedical applications, especially for drug delivery. In this tutorial review, the recent advances of HBPPs are summarized. HBPPs with different topological structures and various functionalities were synthesized via adjusting the side group of cyclic phosphate monomers, which have shown promising biomedical applications, for example, using as a macromolecular anticancer agent and constructing advanced drug delivery systems, including site-specific delivery systems, self-delivery systems, and stimuli-responsive delivery systems. Such progress may promote the further development of interdisciplinary research between polymer chemistry, material science and biomedicine.

  6. Versatile synthesis of end-reactive polyrotaxanes applicable to fabrication of supramolecular biomaterials

    PubMed Central

    Tamura, Atsushi; Tonegawa, Asato; Arisaka, Yoshinori

    2016-01-01

    Cyclodextrin (CD)-threaded polyrotaxanes (PRXs) with reactive functional groups at the terminals of the axle polymers are attractive candidates for the design of supramolecular materials. Herein, we describe a novel and simple synthetic method for end-reactive PRXs using bis(2-amino-3-phenylpropyl) poly(ethylene glycol) (PEG-Ph-NH2) as an axle polymer and commercially available 4-substituted benzoic acids as capping reagents. The terminal 2-amino-3-phenylpropyl groups of PEG-Ph-NH2 block the dethreading of the α-CDs after capping with 4-substituted benzoic acids. By this method, two series of azide group-terminated polyrotaxanes (benzylazide: PRX-Bn-N3, phenylazide: PRX-Ph-N3,) were synthesized for functionalization via click reactions. The PRX-Bn-N3 and PRX-Ph-N3 reacted quickly and efficiently with p-(tert-butyl)phenylacetylene via copper-catalyzed click reactions. Additionally, the terminal azide groups of the PRX-Bn-N3 could be modified with dibenzylcyclooctyne (DBCO)-conjugated fluorescent molecules via a copper-free click reaction; this fluorescently labeled PRX was utilized for intracellular fluorescence imaging. The method of synthesizing end-reactive PRXs described herein is simple and versatile for the design of diverse functional PRXs and can be applied to the fabrication of PRX-based supramolecular biomaterials. PMID:28144361

  7. Versatile synthesis of end-reactive polyrotaxanes applicable to fabrication of supramolecular biomaterials.

    PubMed

    Tamura, Atsushi; Tonegawa, Asato; Arisaka, Yoshinori; Yui, Nobuhiko

    2016-01-01

    Cyclodextrin (CD)-threaded polyrotaxanes (PRXs) with reactive functional groups at the terminals of the axle polymers are attractive candidates for the design of supramolecular materials. Herein, we describe a novel and simple synthetic method for end-reactive PRXs using bis(2-amino-3-phenylpropyl) poly(ethylene glycol) (PEG-Ph-NH2) as an axle polymer and commercially available 4-substituted benzoic acids as capping reagents. The terminal 2-amino-3-phenylpropyl groups of PEG-Ph-NH2 block the dethreading of the α-CDs after capping with 4-substituted benzoic acids. By this method, two series of azide group-terminated polyrotaxanes (benzylazide: PRX-Bn-N3, phenylazide: PRX-Ph-N3,) were synthesized for functionalization via click reactions. The PRX-Bn-N3 and PRX-Ph-N3 reacted quickly and efficiently with p-(tert-butyl)phenylacetylene via copper-catalyzed click reactions. Additionally, the terminal azide groups of the PRX-Bn-N3 could be modified with dibenzylcyclooctyne (DBCO)-conjugated fluorescent molecules via a copper-free click reaction; this fluorescently labeled PRX was utilized for intracellular fluorescence imaging. The method of synthesizing end-reactive PRXs described herein is simple and versatile for the design of diverse functional PRXs and can be applied to the fabrication of PRX-based supramolecular biomaterials.

  8. Ultrahigh throughput silicon nanomanufacturing by simultaneous reactive ion synthesis and etching.

    PubMed

    Chen, Yi; Xu, Zhida; Gartia, Manas R; Whitlock, Daren; Lian, Yaguang; Liu, G Logan

    2011-10-25

    One-dimensional nanostructures, such as nanowhisker, nanorod, nanowire, nanopillar, nanocone, nanotip, nanoneedle, have attracted significant attentions in the past decades owing to their numerous applications in electronics, photonics, energy conversion and storage, and interfacing with biomolecules and living cells. The manufacturing of nanostructured devices relies on either bottom-up approaches such as synthesis or growth process or top-down approaches such as lithography or etching process. Here we report a unique, synchronized, and simultaneous top-down and bottom-up nanofabrication approach called simultaneous plasma enhanced reactive ion synthesis and etching (SPERISE). For the first time the atomic addition and subtraction of nanomaterials are concurrently observed and precisely controlled in a single-step process permitting ultrahigh-throughput, lithography-less, wafer-scale, and room-temperature nanomanufacturing. Rapid low-cost manufacturing of high-density, high-uniformity, light-trapping nanocone arrays was demonstrated on single crystalline and polycrystalline silicon wafers, as well as amorphous silicon thin films. The proposed nanofabrication mechanisms also provide a general guideline to designing new SPERISE methods for other solid-state materials besides silicon.

  9. Local and linear chemical reactivity response functions at finite temperature in density functional theory

    SciTech Connect

    Franco-Pérez, Marco E-mail: ayers@mcmaster.ca E-mail: avela@cinvestav.mx; Ayers, Paul W. E-mail: ayers@mcmaster.ca E-mail: avela@cinvestav.mx; Gázquez, José L. E-mail: ayers@mcmaster.ca E-mail: avela@cinvestav.mx; Vela, Alberto E-mail: ayers@mcmaster.ca E-mail: avela@cinvestav.mx

    2015-12-28

    We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model.

  10. Local and linear chemical reactivity response functions at finite temperature in density functional theory.

    PubMed

    Franco-Pérez, Marco; Ayers, Paul W; Gázquez, José L; Vela, Alberto

    2015-12-28

    We explore the local and nonlocal response functions of the grand canonical potential density functional at nonzero temperature. In analogy to the zero-temperature treatment, local (e.g., the average electron density and the local softness) and nonlocal (e.g., the softness kernel) intrinsic response functions are defined as partial derivatives of the grand canonical potential with respect to its thermodynamic variables (i.e., the chemical potential of the electron reservoir and the external potential generated by the atomic nuclei). To define the local and nonlocal response functions of the electron density (e.g., the Fukui function, the linear density response function, and the dual descriptor), we differentiate with respect to the average electron number and the external potential. The well-known mathematical relationships between the intrinsic response functions and the electron-density responses are generalized to nonzero temperature, and we prove that in the zero-temperature limit, our results recover well-known identities from the density functional theory of chemical reactivity. Specific working equations and numerical results are provided for the 3-state ensemble model.

  11. Odd [n]Cumulenes (n = 3, 5, 7, 9): Synthesis, Characterization, and Reactivity.

    PubMed

    Wendinger, Dominik; Tykwinski, Rik R

    2017-06-20

    In comparison to the omnipresent two- and three-dimensional allotropes of carbon, namely, graphite and diamond (as well as recent entries graphene, carbon nanotubes, and fullerenes), a detailed understanding of the one-dimensional carbon allotrope carbyne is not well established, and even the existence of carbyne has been a matter of controversy over the past decades. Composed of sp-hybridized carbon, carbyne could potentially exist in two forms, either as a polyyne (alternating single and triple bonds, expected to show a semiconducting behavior) or as a cumulene (all carbon atoms are connected via double bonds, predicted to show metallic behavior). Although a number of publications are available on the hypothetical structure and properties of carbyne, specific knowledge about its physical and spectroscopic characteristics is still unclear. In order to predict the properties of carbyne, the synthesis and study of model compounds, namely, polyynes and cumulenes, has been a promising avenue. The synthesis of polyynes has been extensively explored in the last decades, culminating with the isolation of a polyyne with 22 acetylene units, which allows extrapolation to the properties of carbyne. Extended cumulenes, on the other hand, have remained much less well-known, and specific studies of properties versus molecular length are quite limited. A limiting factor to the study of [n]cumulenes has been their dramatically increased reactivity, especially in comparison to polyynes of comparable length. For example, most known [7]cumulenes can only be handled in solution, while the polyynes of equivalent length (i.e., a triyne with three acetylene units) are quite stable. [9]Cumulenes are the longest derivatives studied to date. In this Account, we describe our efforts to design and synthesize odd [n]cumulenes (i.e., n = 3, 5, 7, 9) that are sufficiently persistent under ambient conditions to allow in depth characterization of physical and spectral properties. This goal has

  12. The Role of Reactive Functional Groups in Adhesive Bonding at the Aramid-Epoxy Interface.

    DTIC Science & Technology

    1986-09-15

    sta end ZIP CeO . 800 North Quincy Street i-q ?AiI 3 Arlington, VA 22217 " ae’Iv o. ’to. 6 -o. !The Role of Reactive Functional . . . 1 12. onsRonfaI...Unclassified SICUMI VY’V Ct.ASSiiICATyO OP ’T-S PAGE I Cont ... 11. The Role of Reactive Functional Groups in Adhesive Bonding at the Aramid-Epoxy...T-1 ROLE OF REACTIVE FUNCTIONAL GROUPS IN ADHESIVI 3ODI;G AT THE ARA fID-EPOXY INTIFA> BY L.S. PENN, T.J. BYERLEY, AND T.K. LIAO 1IDWEST RESEARCR

  13. Synthesis of l-cysteine derivatives containing stable sulfur isotopes and application of this synthesis to reactive sulfur metabolome.

    PubMed

    Ono, Katsuhiko; Jung, Minkyung; Zhang, Tianli; Tsutsuki, Hiroyasu; Sezaki, Hiroshi; Ihara, Hideshi; Wei, Fan-Yan; Tomizawa, Kazuhito; Akaike, Takaaki; Sawa, Tomohiro

    2017-05-01

    Cysteine persulfide is an L-cysteine derivative having one additional sulfur atom bound to a cysteinyl thiol group, and it serves as a reactive sulfur species that regulates redox homeostasis in cells. Here, we describe a rapid and efficient method of synthesis of L-cysteine derivatives containing isotopic sulfur atoms and application of this method to a reactive sulfur metabolome. We used bacterial cysteine syntheses to incorporate isotopic sulfur atoms into the sulfhydryl moiety of L-cysteine. We cloned three cysteine synthases-CysE, CysK, and CysM-from the Gram-negative bacterium Salmonella enterica serovar Typhimurium LT2, and we generated their recombinant enzymes. We synthesized (34)S-labeled L-cysteine from O-acetyl-L-serine and (34)S-labeled sodium sulfide as substrates for the CysK or CysM reactions. Isotopic labeling of L-cysteine at both sulfur ((34)S) and nitrogen ((15)N) atoms was also achieved by performing enzyme reactions with (15)N-labeled L-serine, acetyl-CoA, and (34)S-labeled sodium sulfide in the presence of CysE and CysK. The present enzyme systems can be applied to syntheses of a series of L-cysteine derivatives including L-cystine, L-cystine persulfide, S-sulfo-L-cysteine, L-cysteine sulfonate, and L-selenocystine. We also prepared (34)S-labeled N-acetyl-L-cysteine (NAC) by incubating (34)S-labeled L-cysteine with acetyl coenzyme A in test tubes. Tandem mass spectrometric identification of low-molecular-weight thiols after monobromobimane derivatization revealed the endogenous occurrence of NAC in the cultured mammalian cells such as HeLa cells and J774.1 cells. Furthermore, we successfully demonstrated, by using (34)S-labeled NAC, metabolic conversion of NAC to glutathione and its persulfide, via intermediate formation of L-cysteine, in the cells. The approach using isotopic sulfur labeling combined with mass spectrometry may thus contribute to greater understanding of reactive sulfur metabolome and redox biology. Copyright © 2017 Elsevier

  14. Amine-Reactive Fluorene Probes: Synthesis, Optical Characterization, Bioconjugation, and Two-Photon Fluorescence Imaging

    PubMed Central

    2008-01-01

    With the increasing demand for confocal and two-photon fluorescence imaging, the availability of reactive probes that possess high two-photon absorptivity, high fluorescence quantum yield, and high photostability is of paramount importance. To address the demand for better-performing probes, we prepared two-photon absorbing amine-reactive fluorenyl-based probes 2-(9,9-bis(2-(2-methoxyethoxy)ethyl)-2-isothiocyanato-9H-fluoren-7-yl)benzothiazole (1) and 2-(4-(2-(9,9-bis(2-(2-ethoxyethoxy)ethyl)-2-isothiocyanato-9H-fluoren-7-yl)vinyl)phenyl)benzothiazole (2), incorporating the isothiocyanate as a reactive linker. Probe design was augmented by integrating high optical nonlinearities, increased hydrophilicity, and coupling with reactive functional groups for specific targeting of biomolecules, assuring a better impact on two-photon fluorescence microscopy (2PFM) imaging. The isothiocyanate (NCS) derivatives were conjugated with cyclic peptide RGDfK and Reelin protein. The study of the chemical and photophysical properties of the new labeling reagents, as well as the conjugates, is described. The conjugates displayed high chemical stability and photostability. The NCS derivatives had low fluorescence quantum yields, while their bioconjugates exhibited high fluorescence quantum yields, essentially “lighting up” after conjugation. Conventional and 2PFM imaging and fluorescence lifetime imaging (FLIM) of HeLa, NT2, and H1299 cells, incubated with two-photon absorbing amine-reactive probe (1), RGDfK-dye conjugate (7), and Reelin-dye conjugate (6), was demonstrated. PMID:19090700

  15. Synthesis and functionalization of coiled carbon filaments

    NASA Astrophysics Data System (ADS)

    Hikita, Muneaki

    Coiled carbon filaments have one of the most attractive three-dimensional forms in carbon materials due to their helical morphologies. Because of their shape and carbon structure, they exhibit excellent mechanical and electrical properties such as superelasticity, low Young's modulus, relatively high electrical conductivity, and good electromagnetic (EM) wave absorption. Therefore, they are good candidates as fillers in composite materials for tactile sensor and electromagnetic interference shielding. In medical areas of interests, coiled carbon filaments can be used as micro and nano heaters or trigger for thermotherapy and biosensors using EM wave exposure because absorbed EM waves by coiled carbon filaments are converted into heat. Although various shapes of coiled carbon filaments have been discovered, optimum synthesis conditions and growth mechanisms of coiled carbon filaments are poorly understood. The study of growth kinetics is significant not only to analyze catalyst activity but also to establish the growth mechanisms of coiled carbon filaments. The establishment of growth mechanisms would be useful for determining optimum synthesis conditions and maximizing the quantity of carbon filaments synthesized for a given application. In the first study, tip grown single helical carbon filaments or carbon nanocoils (CNCs) were synthesized by a chemical vapor deposition method using tin-iron-oxide (Sn-Fe-O) xerogel film catalyst. The Sn-Fe-O catalyst was prepared by a low-cost sol-gel method using stannous acetate and ferric acetate as precursors. The growth kinetics of CNCs were monitored by a thermogravimetric analyzer, and the experimental result was correlated using a one-dimensional kinetic model, corresponding to one-dimensional tip growth. In the second study, bidirectionally grown double helical filaments or carbon microcoils (CMCs) were synthesized using a chemical vapor deposition method. CMCs obtained at two reaction temperatures were compared. CMCs

  16. Polyamines function in stress tolerance: from synthesis to regulation

    PubMed Central

    Liu, Ji-Hong; Wang, Wei; Wu, Hao; Gong, Xiaoqing; Moriguchi, Takaya

    2015-01-01

    Plants are challenged by a variety of biotic or abiotic stresses, which can affect their growth and development, productivity, and geographic distribution. In order to survive adverse environmental conditions, plants have evolved various adaptive strategies, among which is the accumulation of metabolites that play protective roles. A well-established example of the metabolites that are involved in stress responses, or stress tolerance, is the low-molecular-weight aliphatic polyamines, including putrescine, spermidine, and spermine. The critical role of polyamines in stress tolerance is suggested by several lines of evidence: firstly, the transcript levels of polyamine biosynthetic genes, as well as the activities of the corresponding enzymes, are induced by stresses; secondly, elevation of endogenous polyamine levels by exogenous supply of polyamines, or overexpression of polyamine biosynthetic genes, results in enhanced stress tolerance; and thirdly, a reduction of endogenous polyamines is accompanied by compromised stress tolerance. A number of studies have demonstrated that polyamines function in stress tolerance largely by modulating the homeostasis of reactive oxygen species (ROS) due to their direct, or indirect, roles in regulating antioxidant systems or suppressing ROS production. The transcriptional regulation of polyamine synthesis by transcription factors is also reviewed here. Meanwhile, future perspectives on polyamine research are also suggested. PMID:26528300

  17. The Synthesis of Functional Mesoporous Materials

    SciTech Connect

    Fryxell, Glen E.

    2006-11-01

    The ability to decorate a silica surface with specific ligand fields and/or metal complexes creates powerful new capabilities for catalysis, chemical separations and sensor development. Integrating this with the ability to control the spacing of these complexes across the surface, as well as the symmetry and size of the pore structure, allows the synthetic chemist to hierarchically tailor these structured nanomaterials to specific needs. The next step up the “scale ladder” is provided by the ability to coat these mesoporous materials onto complex shapes, allowing for the intimate integration of these tailored materials into device interfaces. The ability to tailor the pore structure of these mesoporous supports is derived from the surfactant templated synthesis of mesoporous materials, an area which has seen an explosion of activity over the last decade.[1,2] The ability to decorate the surface with the desired functionality requires chemical modification of the oxide interface, most commonly achieved using organosilane self-assembly.[3-6] This manuscript describes recent results from the confluence of these two research areas, with a focus on synthetic manipulation of the morphology and chemistry of the interface, with the ultimate goal of binding metal centers in a chemically useful manner.

  18. Multivariable synthesis with transfer functions. [applications to gas turbine engines

    NASA Technical Reports Server (NTRS)

    Peczkowski, J. L.

    1980-01-01

    A transfer function design theory for multivariable control synthesis is highlighted. The use of unique transfer function matrices and two simple, basic relationships - a synthesis equation and a design equation - are presented and illustrated. This multivariable transfer function approach provides the designer with a capability to specify directly desired dynamic relationships between command variables and controlled or response variables. At the same time, insight and influence over response, simplifications, and internal stability is afforded by the method. A general, comprehensive multivariable synthesis capability is indicated including nonminmum phase and unstable plants. Gas turbine engine examples are used to illustrate the ideas and method.

  19. Simulation of Gold Functionalization with Cysteine by Reactive Molecular Dynamics.

    PubMed

    Monti, Susanna; Carravetta, Vincenzo; Ågren, Hans

    2016-01-21

    The anchoring mechanism of cysteine to gold in water solution is characterized in detail by means of a combination of quantum chemistry (QC) and reactive classical molecular dynamics (RC-MD) calculations. A possible adsorption-reaction route is proposed, through RC-MD simulations based on a modified version of the protein reactive force field (ReaxFF), in which gold-protein interactions have been included after accurate parametrization at the QC level. The computational results confirm recent experimental findings regarding the mechanism as a two-step binding, namely, a slow physisorption followed by a fast chemisorption. The reaction barriers are estimated through the nudged elastic band approach and checked by QC calculations. Surface reconstructions, induced by the strong adsorption of the molecule, are identified, and their role, as further adsorbate stabilizers, is properly disclosed. The satisfactory agreement with QC data and experiments confirm the reliability of the simulations and the unique opportunity they provide to follow locally molecule adsorption on selected materials.

  20. Investigation of PAA/PVDF-NZVI hybrids for metronidazole removal: synthesis, characterization, and reactivity characteristics.

    PubMed

    Yang, Jiacheng; Wang, Xiangyu; Zhu, Minping; Liu, Huiling; Ma, Jun

    2014-01-15

    For the first time, the removal process of metronidazole (MNZ) from aqueous solutions over nano zerovalent iron (NZVI) encapsulated within poly(acrylic acid) (PAA)/poly(vinylidene fluoride) (PVDF) membranes was reported. The resultant composite (PPN) demonstrated high reactivity, excellent stability and reusability over the reaction course. Such excellent performance might be attributed to the presence of the charged carboxyl groups in PVDF membrane support, which could enhance NZVI dispersion and improve its longevity. Results showed that a lower initial concentration and higher reaction temperature facilitated the removal of MNZ by PPN, and that the acidic and neutral conditions generally exhibited more favorable effect on MNZ removal than the alkaline ones. Kinetics of the MNZ removal by PPN was found to follow a two-parameter pseudo-first-order decay model well, and the activation energy of the MNZ degradation by PPN was determined to be 30.49kJ/mol. The presence of chloride ions slightly enhanced the reactivity of PPN with MNZ, whereas sulfate ions inhibited its reactivity. In addition, MNZ degradation pathways by PPN were proposed based on the identified intermediates. This study suggests that PPN composite possessing excellent performance may be a promising functional material to pretreat antibiotic wastewaters. Copyright © 2013 Elsevier B.V. All rights reserved.

  1. A highly reactive chalcogenide precursor for the synthesis of metal chalcogenide quantum dots

    NASA Astrophysics Data System (ADS)

    Jiang, Peng; Zhu, Dong-Liang; Zhu, Chun-Nan; Zhang, Zhi-Ling; Zhang, Guo-Jun; Pang, Dai-Wen

    2015-11-01

    Metal chalcogenide semiconductor nanocrystals (NCs) are ideal inorganic materials for solar cells and biomedical labeling. In consideration of the hazard and instability of alkylphosphines, the phosphine-free synthetic route has become one of the most important trends in synthesizing selenide QDs. Here we report a novel phase transfer strategy to prepare phosphine-free chalcogenide precursors. The anions in aqueous solution were transferred to toluene via electrostatic interactions between the anions and didodecyldimethylammonium bromide (DDAB). The obtained chalcogenide precursors show high reactivity with metal ions in the organic phase and could be applied to the low-temperature synthesis of various metal chalcogenide NCs based on a simple reaction between metal ions (e.g. Ag+, Pb2+, Cd2+) and chalcogenide anions (e.g. S2-) in toluene. In addition to chalcogenide anions, other anions such as BH4- ions and AuCl4- ions can also be transferred to the organic phase for synthesizing noble metal NCs (such as Ag and Au NCs).Metal chalcogenide semiconductor nanocrystals (NCs) are ideal inorganic materials for solar cells and biomedical labeling. In consideration of the hazard and instability of alkylphosphines, the phosphine-free synthetic route has become one of the most important trends in synthesizing selenide QDs. Here we report a novel phase transfer strategy to prepare phosphine-free chalcogenide precursors. The anions in aqueous solution were transferred to toluene via electrostatic interactions between the anions and didodecyldimethylammonium bromide (DDAB). The obtained chalcogenide precursors show high reactivity with metal ions in the organic phase and could be applied to the low-temperature synthesis of various metal chalcogenide NCs based on a simple reaction between metal ions (e.g. Ag+, Pb2+, Cd2+) and chalcogenide anions (e.g. S2-) in toluene. In addition to chalcogenide anions, other anions such as BH4- ions and AuCl4- ions can also be transferred to

  2. Exploring the surface reactivity of 3d metal endofullerenes: a density-functional theory study.

    PubMed

    Estrada-Salas, Rubén E; Valladares, Ariel A

    2009-09-24

    Changes in the preferential sites of electrophilic, nucleophilic, and radical attacks on the pristine C60 surface with endohedral doping using 3d transition metal atoms were studied via two useful reactivity indices, namely the Fukui functions and the molecular electrostatic potential. Both of these were calculated at the density functional BPW91 level of theory with the DNP basis set. Our results clearly show changes in the preferential reactivity sites on the fullerene surface when it is doped with Mn, Fe, Co, or Ni atoms, whereas there are no significant changes in the preferential reactivity sites on the C60 surface upon endohedral doping with Cu and Zn atoms. Electron affinities (EA), ionization potentials (IP), and HOMO-LUMO gaps (Eg) were also calculated to complete the study of the endofullerene's surface reactivity. These findings provide insight into endofullerene functionalization, an important issue in their application.

  3. Biogenic nanoparticulate UO2: Synthesis, characterization, and factors affecting surface reactivity

    NASA Astrophysics Data System (ADS)

    Singer, D. M.; Farges, F.; Brown, G. E.

    2008-12-01

    The surface reactivity of biogenic, nanoparticulate UO2 with respect to sorption of aqueous Zn(II) and particle annealing is different from that of bulk uraninite because of differences in particle size and the presence of surface-associated organic matter on the biogenic UO2. Synthesis of biogenic UO2 was accomplished by reduction of aqueous uranyl ions, UO22+ by Shewanella putrefaciens CN32, and the resulting nanoparticles were washed using one of two protocols: (1) 10 percent NaOH, followed by 4 mM KHCO3/KCl (particles referred to as NAUO2) to remove surface-associated organic matter and soluble uranyl species, or (2) 4 mM KHCO3-KCl (particles referred to as BIUO2) to remove only soluble uranyl species. A suite of bulk and surface characterization techniques was used to examine bulk and biogenic, nanoparticulate UO2 as a function of particle size and surface-associated organic matter. The N2-BET surface areas of the two biogenic UO2 samples following the washing procedures are 128.63 m2g-1 (NAUO2) and 92.56 m2g-1 (BIUO2), and the average particle sizes range from 5-10 nm based on TEM imaging. Electrophoretic mobility measurements indicate that the surface charge behavior of biogenic, nanoparticulate UO2 over the pH range 3-9 is the same as that of bulk uraninite (avg. diameter = 500 nm) (pHpzc = 5.6±0.03) and that there is no observed effect on surface charge caused by surface-associated organic matter for sample BIUO2. Both XPS and U LIII-edge XANES spectroscopy revealed that the uranium oxidation state of the biogenic, nanoparticulate samples is 4+, which is consistent with stoichiometric UO2. The EXAFS spectra for biogenic UO2 were best fit with half the number of second-shell uranium neighbors compared to bulk uraninite, and no oxygen neighbors were detected beyond the first shell around U(IV) in the biogenic UO2. At pH 7, sorption of Zn(II) onto both finely ground, bulk uraninite (500 nm average particle diameter) and biogenic, nanoparticulate UO2 is

  4. Synthesis, bonding, and reactivity of a cerium(IV) fluoride complex.

    PubMed

    Williams, Ursula J; Robinson, Jerome R; Lewis, Andrew J; Carroll, Patrick J; Walsh, Patrick J; Schelter, Eric J

    2014-01-06

    Oxidation of Ce[N(SiMe3)2]3 in the presence of PF6(-) or BF4(-) afforded isolation of CeF[N(SiMe3)2]3. Structural and electrochemical characterization shows that this compound is in its tetravalent oxidation state and contains a terminal fluoride ligand. Spectroscopy and density functional theory have been used to characterize the Ce-F bond as ionic, which is reinforced by an initial reactivity study that demonstrates the nucleophilicity of the fluoride ligand.

  5. Direct synthesis and integration of functional nanostructures in microfluidic devices.

    PubMed

    Kim, Jung; Li, Zhiyong; Park, Inkyu

    2011-06-07

    Integration of functional nanostructures within a microfluidic device can synergize the advantages of both unique properties of nanomaterials and diverse functionalities of microfluidics. In this paper, we report a novel and simple method for the in situ synthesis and integration of ZnO nanowires by controlled hydrothermal reaction within microfluidic devices. By modulating synthesis parameters such as the seed preparation, synthesis time, and heating locations, the morphology and location of synthesized nanowires can be easily controlled. The applications of such nanostructure-integrated microfluidics for particle trapping and chemiresistive pH sensing were demonstrated.

  6. Scar Functions, Barriers for Chemical Reactivity, and Vibrational Basis Sets.

    PubMed

    Revuelta, F; Vergini, E; Benito, R M; Borondo, F

    2016-07-14

    The performance of a recently proposed method to efficiently calculate scar functions is analyzed in problems of chemical interest. An application to the computation of wave functions associated with barriers relevant for the LiNC ⇄ LiCN isomerization reaction is presented as an illustration. These scar functions also constitute excellent elements for basis sets suitable for quantum calculation of vibrational energy levels. To illustrate their efficiency, a calculation of the LiNC/LiCN eigenfunctions is also presented.

  7. Synthesis of protected 2-amino-2-deoxy-D-xylothionolactam derivatives and some aspects of their reactivity.

    PubMed

    Devel, Laurent; Hamon, Louis; Becker, Hubert; Thellend, Annie; Vidal-Cros, Anne

    2003-07-22

    The synthesis of polyfunctionalized delta-lactams as key intermediates of glycomimetics in the 2-acetamido-2-deoxy sugar series is presented. Starting from a chiral gamma-amino vinylic ester synthesized from Garner's aldehyde and after regioselective reduction, 1-azido-3-(N-tert-butyloxycarbonyl-2,2-dimethyloxazolidin-4-yl)-2-propene was obtained. Next, a cis-dihydroxylation reaction provided the protected D-xylitol and L-arabinitol azides. A simple protection-deprotection sequence, followed by an oxidation and a reductive cyclization, led to protected 2-amino-delta-lactams bearing a tert-butyloxycarbonyl group on the amine functionality. To explore the reactivity of such compounds, activation of the lactam into the corresponding thionolactam was performed. The resulting 2-amino-D-xylothionolactam derivative, a versatile intermediate, allowed access to a first generation of protected 2-amino-D-xylosamidoxime derivatives which are of interest as precursors of N-acetylhexosaminidase and N-acetylglucosaminyltransferase inhibitors. In this series of compounds, epimerization at C-2 was observed. AM(1) calculations performed on these analogs showed that they adopted a B(2,5) conformation and that the axial epimer was favored in the protected series whereas the equatorial epimer was preferred in the unprotected series.

  8. Towards the new heterocycle based molecule: Synthesis, characterization and reactivity study

    NASA Astrophysics Data System (ADS)

    Murthy, P. Krishna; Sheena Mary, Y.; Suneetha, V.; Panicker, C. Yohannan; Armaković, Stevan; Armaković, Sanja J.; Giri, L.; Suchetan, P. A.; Van Alsenoy, C.

    2017-06-01

    4-Chloro-2-(3-fluorophenyl)-2,3-dihydro-1H-pyrrolo[3,4-c]pyridin-1-one (CFPDPPO) have been synthesized by hydride transfer from Et3SiH to carbenium ions(reduction reaction), which is formed by reaction between 4-chloro-2-(3-fluorophenyl)-3-hydroxy-2,3-dihydro-1H-pyrrolo[3,4-c]pyridin-1-one with TFA, the single crystals were grown in acetonitrile by slow evaporation technique at room temperature and characterized by single crystal X-ray diffraction, FT-IR, FT-Raman, 1H NMR, 13C NMR and ESI-MS. The experimental vibrational spectra were compared with the calculated spectra and each vibrational wavenumber was assigned on the basis of potential energy distribution (PED). Gauge-including atomic orbital 1H NMR and 13C NMR chemical shifts calculations were carried out and compared with experimental data. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analysed using NBO analysis. First hyperpolarizability is calculated in order to find its role in non-linear optics. Besides molecular electrostatic potential (MEP), global reactivity descriptors, thermodynamic properties, and Mullikan charge analysis of the title compound were computed with the same method in gas phase, theoretically. Further, employing combination of DFT calculations and molecular dynamics (MD) simulations, we have investigated in detail reactive properties of the title molecule. Investigation of local reactive properties encompassed calculations of average local ionization energies (ALIE) and Fukui functions. Stability in water has been investigated by calculations of radial distribution functions (RDF), while sensitivity towards the mechanism of autoxidation has been investigated by calculations of bond dissociation energies (BDE). The docked ligand forms a stable complex with human alpha9 nicotinic acetylcholine receptor antagonist and can be a lead

  9. Reaction design, discovery, and development as a foundation to function-oriented synthesis.

    PubMed

    Micalizio, Glenn C; Hale, Sarah B

    2015-03-17

    Convergent C-C bond-forming reactions define the fabric of organic synthesis and, when applied in complex molecule synthesis, can have a profound impact on efficiency by decreasing the longest linear sequence of transformations required to convert simple starting materials to complex targets. Despite their well-appreciated strategic significance, campaigns in natural product synthesis typically embrace only a small suite of reactivity to achieve such bond construction (i.e., nucleophilic addition to polarized π-bonds, nucleophilic substitution, cycloaddition, and metal-catalyzed "cross-coupling"), therefore limiting the sites at which convergent coupling chemistry can be strategically employed. In our opinion, it is far too often that triumphs in the field are defined by chemical sequences that do not address the challenges associated with discovery, development, and production of natural product-inspired agents. We speculated that advancing an area of chemical reactivity not represented in the few well-established strategies for convergent C-C bond formation may lead to powerful new retrosynthetic relationships that could simplify approaches to the syntheses of a variety of different classes of natural products. Our studies ultimately embraced the pursuit of strategies to control the course of metallacycle-mediated "cross-coupling" between substrates containing sites of simple π-unsaturation (ubiquitous functionality in organic chemistry including alkenes, alkynes, allenes, aldehydes, and imines, among others). In just eight years since our initial publication in this area, we have defined over 20 stereoselective intermolecular C-C bond-forming reactions that provide access to structural motifs of relevance for the synthesis of polyketides, fatty acids, alkaloids, and terpenes, while doing so in a direct and stereoselective fashion. These achievements continue to serve as the foundation of my group's activity in natural product and function-oriented synthesis

  10. Linkage of functional and structural anomalies in the left amygdala of reactive-aggressive men

    PubMed Central

    Ostrosky, Feggy; Diaz, Karla; Romero, Cesar; Borja, Karina; Santos, Yusniel; Valdés-Sosa, Mitchell

    2013-01-01

    Amygdala structural and functional abnormalities have been associated to reactive aggression in previous studies. However, the possible linkage of these two types of anomalies has not been examined. We hypothesized that they would coincide in the same localizations, would be correlated in intensity and would be mediated by reactive aggression personality traits. Here violent (n = 25) and non-violent (n = 29) men were recruited on the basis of their reactive aggression. Callous-unemotional (CU) traits were also assessed. Gray matter concentration (gmC) and reactivity to fearful and neutral facial expressions were measured in dorsal and ventral amygdala partitions. The difference between responses to fearful and neutral facial expressions was calculated (F/N-difference). Violent individuals exhibited a smaller F/N-difference and gmC in the left dorsal amygdala, where a significant coincidence was found in a conjunction analysis. Moreover, the left amygdala F/N-difference and gmC were correlated to each other, an effect mediated by reactive aggression but not by CU. The F/N-difference was caused by increased reactivity to neutral faces. This suggests that anatomical anomalies within local circuitry (and not only altered input) may underlie the amygdala hyper-reactivity to social signals which is characteristic of reactive aggression. PMID:22956672

  11. Synthesis of Alkaline-Soluble Cellulose Methyl Carbamate Using a Reactive Deep Eutectic Solvent.

    PubMed

    Sirviö, Juho Antti; Heiskanen, Juha P

    2017-01-20

    This study presents the use of a reactive deep eutectic solvent (DES) for the chemical modification of wood cellulose fibers. DES based on dimethylurea and ZnCl2 was used to synthetize cellulose methyl carbamate (CMeC). This synthesis was performed at elevated temperature under solvent-free conditions. Chemical characterization based on FTIR and NMR indicated that methyl carbamate was successfully introduced to cellulose, and a degree of substitution (DS) of 0.17 was obtained after 3 h of reaction at 150 °C. The product with a DS of 0.17 exhibited good alkaline solubility (in 3 % NaOH solution) after freeze-thawing, whereas the original cellulose fibers were practically insoluble even in 9 % NaOH. As dimethylurea can be produced from CO2 , this method can be used as a sustainable way to obtain novel cellulose materials with desirable properties for use in a wide range of applications.

  12. Development of a new graded-porosity FeAl alloy by elemental reactive synthesis

    SciTech Connect

    Shen, P Z; He, Y H; Gao, H Y; Zou, J; Xu, N P; Jiang, Y; Huang, B; Lui, C T

    2009-01-01

    A new graded-porosity FeAl alloy can be fabricated through Fe and Al elemental reactive synthesis. FeAl alloy with large connecting open pores and permeability were used as porous supports. The coating was obtained by spraying slurries consisting of mixtures of Fe powder and Al powder with 3 5 m diameter onto porous FeAl support and then sintered at 1100 C. The performances of the coating were compared in terms of thickness, pore diameter and permeability. With an increase in the coating thickness up to 200 m, the changes of maximum pore size decreased from 23.6 m to 5.9 m and the permeability decreased from 184.2 m3m 2kPa 1h 1 to 76.2 m3m 2kPa 1h 1, respectively, for a sintering temperature equal to 1100 C. The composite membranes have potential application for excellent filters in severe environments.

  13. Exploration of Visible-Light Photocatalysis in Heterocycle Synthesis and Functionalization: Reaction Design and Beyond.

    PubMed

    Chen, Jia-Rong; Hu, Xiao-Qiang; Lu, Liang-Qiu; Xiao, Wen-Jing

    2016-09-20

    Visible-light photocatalysis has recently received increasing attention from chemists because of its wide application in organic synthesis and its significance for sustainable chemistry. This catalytic strategy enables the generation of various reactive species, frequently without stoichiometric activation reagents under mild reaction conditions. Manipulation of these reactive intermediates can result in numerous synthetically useful bond formations in a controllable manner. In this Account, we describe our recent advances in the rational design and strategic application of photocatalysis in the synthesis of various synthetically and biologically important heterocycles. Our main research efforts toward this goal can be classified into four categories: formal cycloaddition and cyclization reactions, radical-mediated olefin functionalization/cyclization cascades, photocatalytic generation and cyclization of N-centered radicals, and photocatalytic functionalization of heterocycles by visible-light-induced dual catalysis. Inspired by the wide application of tertiary amines as reductive additives in photoredox catalysis, we exploited a series of readily accessible or rationally designed tertiary amines with reactive sites in a range of photocatalytic formal cycloaddition and cyclization reactions, providing efficient access to diverse nitrogen heterocycles. Employing various photogenerated radical species, we further developed a series of radical-mediated olefin functionalization/cyclization cascade reactions to successfully assemble various five- and six-membered heterocycles. We have also achieved for the first time the direct catalytic conversion of recalcitrant N-H bonds into neutral N-centered radicals through a visible-light-photocatalytic oxidative deprotonation electron transfer. Using this generic strategy, we have devised several types of radical cyclizations of unsaturated hydrazones, leading to the construction of diversely functionalized pyrazoline and

  14. Recent advances in development of imidazo[1,2-a]pyrazines: synthesis, reactivity and their biological applications.

    PubMed

    Goel, Richa; Luxami, Vijay; Paul, Kamaldeep

    2015-03-28

    Imidazo[1,2-a]pyrazine acts as a versatile scaffold in organic synthesis and drug development. This review article is an effort to compile the progress made in synthetic methods and to illustrate its reactivity and multifarious biological activity. This review is mainly based on the pattern and position of the substitution, and should help the scientific community to bring about future developments.

  15. Hardness and softness reactivity kernels within the spin-polarized density-functional theory

    SciTech Connect

    Chamorro, Eduardo; De Proft, Frank; Geerlings, Paul

    2005-10-15

    Generalized hardness and softness reactivity kernels are defined within a spin-polarized density-functional theory (SP-DFT) conceptual framework. These quantities constitute the basis for the global, local (i.e., r-position dependent), and nonlocal (i.e., r and r{sup '}-position dependents) indices devoted to the treatment of both charge-transfer and spin-polarization processes in such a reactivity framework. The exact relationships between these descriptors within a SP-DFT framework are derived and the implications for chemical reactivity in such context are outlined.

  16. Synthesis Of Reactive Nano-Fe/Pd Bimetallic System-Impregnated Activated Carbon For The Simultaneous Adsorption And Dechlorination Of PCBs

    EPA Science Inventory

    Synthesis and use of reactive metal particles have shown significant environmental implications for the remediation of groundwater and sediment contaminated with chlorinated compounds. Herein, we have developed an effective strategy, employing a series of innovative granular act...

  17. Synthesis Of Reactive Nano-Fe/Pd Bimetallic System-Impregnated Activated Carbon For The Simultaneous Adsorption And Dechlorination Of PCBs

    EPA Science Inventory

    Synthesis and use of reactive metal particles have shown significant environmental implications for the remediation of groundwater and sediment contaminated with chlorinated compounds. Herein, we have developed an effective strategy, employing a series of innovative granular act...

  18. Azodicarboxylates: synthesis and functionalization of organic compounds

    NASA Astrophysics Data System (ADS)

    Zhirov, A. M.; Aksenov, A. V.

    2014-06-01

    The data on transformations of dialkyl azodicarboxylates and their analogues involving various substrates are generalized. Nucleophilic addition and oxidation, pericyclic reactions and reactions occurring under the Mitsunobu reaction conditions are considered. Ample opportunities for application of these compounds in fine organic synthesis are shown. The bibliography includes 245 references. Dedicated to Academician B A Trofimov on the occasion of his 75th birthday.

  19. A Trinuclear Ni(II) Enediolate Complex: Synthesis, Characterization, and O2 Reactivity

    PubMed Central

    Arif, Atta M.; Berreau, Lisa M.

    2009-01-01

    Using a new N4-donor chelate ligand having a mixture of hydrophobic phenyl and hydrogen bond donor appendages, a trinuclear Ni(II) complex of the doubly deprotonated form of 2-hydroxy-1,3-diphenylpropane-1,3-dione was isolated, characterized (X-ray crystallography, elemental analysis, UV-vis, 1H NMR, FTIR, magnetic moment measurement), and evaluated for O2 reactivity. This complex, [(6-NA-6-Ph2TPANi)2(μ-PhC(O)C(O)C(O)Ph)2Ni](ClO4)2 (4), has two terminal pseudo octahedral Ni(II) centers supported by the tetradentate chelate ligand, and a central square planar Ni(II) ion ligated by oxygen atoms of two bridging enediolate ligands. In CH3CN, 4 exhibits a deep orange/brown color and λmax = 463 nm (ε = 16,000 M-1cm-1). The room temperature magnetic moment of 4, determined by Evans method, is μeff = 5.3(2) μB. This is consistent with the presence of two non-interacting high-spin Ni(II) centers, a diamagnetic central Ni(II) ion, and an overall quintet ground state. Exposure of a CH3CN solution of 4 to O2 results in the rapid loss of the orange/brown color to give a green solution. The products identified from this reaction are [(κ3-6-NA-6-Ph2TPA)Ni(O2Ph)(H2O)]ClO4 (5), benzil (PhC(O)C(O)Ph), and CO. Identification of 5 was achieved via its independent synthesis and comparison of its 1H NMR and mass spectral features with those of the 6-NA-6-Ph2TPA-containing product generated upon reaction of 4 with O2. The independently prepared sample of 5 was characterized by X-ray crystallography, elemental analysis, UV-vis, mass spectrometry, and FTIR. The O2 reactivity of 4 has relevance to the active site chemistry of Ni(II)-containing acireductone dioxygenase (Ni(II)-ARD). PMID:18959363

  20. Synthesis, characterization and reactivity of heteroleptic rare earth metal bis(phenolate) complexes.

    PubMed

    Qi, Ruipeng; Liu, Bao; Xu, Xiaoping; Yang, Zijian; Yao, Yingming; Zhang, Yong; Shen, Qi

    2008-10-07

    The synthesis, characterization and reactivity of heteroleptic rare earth metal complexes supported by the carbon-bridged bis(phenolate) ligand 2,2'-methylene-bis(6-tert-butyl-4-methyl-phenoxo) (MBMP2-) are described. Reaction of (C5H5)3Ln(THF) with MBMPH2 in a 1:1.5 molar ratio in THF at 50 degrees C produced the heteroleptic rare earth metal bis(phenolate) complexes (C5H5)Ln(MBMP)(THF)n (Ln=La, n=3 (); Ln=Yb (), Y (), n=2) in nearly quantitative yields. The residual C5H5- groups in complexes to can be substituted by the bridged bis(phenolate) ligands at elevated temperature to give the neutral rare earth metal bis(phenolate) complexes, and the ionic radii have a profound effect on the structures of the final products. Complex reacted with MBMPH2 in a 1:0.5 molar ratio in toluene at 80 degrees C to produce a dinuclear complex (MBMP)La(THF)(micro-MBMP)2La(THF)2 () in good isolated yield; whereas complexes and reacted with MBMPH2 under the same conditions to give (MBMP)Ln(MBMPH)(THF)2 (Ln=Yb (), Y ()) as the final products, in which one hydroxyl group of the phenol is coordinated to the rare earth metal in a neutral fashion. The reactivity of complexes and with some metal alkyls was explored. Reaction of complex with 1 equiv. of AlEt3 in toluene at room temperature afforded unexpected ligand redistributed products, and a discrete ion pair ytterbium complex [(MBMP)Yb(THF)2(DME)][(MBMP)2Yb(THF)2] () was isolated in moderate yield. Furthermore, reaction of complex with 1 equiv. of ZnEt2 in toluene gave a ligand redistributed complex [(micro-MBMP)Zn(THF)]2 () in reasonable isolated yield. Similar reaction of complex with ZnEt2 also afforded complex ; whereas the reaction of complex with 1 equiv. of n-BuLi in THF afforded the heterodimetallic complex [(THF)Yb(MBMP)2Li(THF)2] (). All of these complexes were well characterized by elemental analyses, IR spectra, and single-crystal structure determination, in the cases of complexes , and -.

  1. Highly reactive {001} facets of TiO2-based composites: synthesis, formation mechanism and characterization.

    PubMed

    Ong, Wee-Jun; Tan, Lling-Lling; Chai, Siang-Piao; Yong, Siek-Ting; Mohamed, Abdul Rahman

    2014-02-21

    Titanium dioxide (TiO2) is one of the most widely investigated metal oxides due to its extraordinary surface, electronic and catalytic properties. However, the large band gap of TiO2 and massive recombination of photogenerated electron-hole pairs limit its photocatalytic and photovoltaic efficiency. Therefore, increasing research attention is now being directed towards engineering the surface structure of TiO2 at the most fundamental and atomic level namely morphological control of {001} facets in the range of microscale and nanoscale to fine-tune its physicochemical properties, which could ultimately lead to the optimization of its selectivity and reactivity. The synthesis of {001}-faceted TiO2 is currently one of the most active interdisciplinary research areas and demonstrations of catalytic enhancement are abundant. Modifications such as metal and non-metal doping have also been extensively studied to extend its band gap to the visible light region. This steady progress has demonstrated that TiO2-based composites with {001} facets are playing and will continue to play an indispensable role in the environmental remediation and in the search for clean and renewable energy technologies. This review encompasses the state-of-the-art research activities and latest advancements in the design of highly reactive {001} facet-dominated TiO2via various strategies, including hydrothermal/solvothermal, high temperature gas phase reactions and non-hydrolytic alcoholysis methods. The stabilization of {001} facets using fluorine-containing species and fluorine-free capping agents is also critically discussed in this review. To overcome the large band gap of TiO2 and rapid recombination of photogenerated charge carriers, modifications are carried out to manipulate its electronic band structure, including transition metal doping, noble metal doping, non-metal doping and incorporating graphene as a two-dimensional (2D) catalyst support. The advancements made in these aspects are

  2. Computational Study of Chemical Reactivity Using Information-Theoretic Quantities from Density Functional Reactivity Theory for Electrophilic Aromatic Substitution Reactions.

    PubMed

    Wu, Wenjie; Wu, Zemin; Rong, Chunying; Lu, Tian; Huang, Ying; Liu, Shubin

    2015-07-23

    The electrophilic aromatic substitution for nitration, halogenation, sulfonation, and acylation is a vastly important category of chemical transformation. Its reactivity and regioselectivity is predominantly determined by nucleophilicity of carbon atoms on the aromatic ring, which in return is immensely influenced by the group that is attached to the aromatic ring a priori. In this work, taking advantage of recent developments in quantifying nucleophilicity (electrophilicity) with descriptors from the information-theoretic approach in density functional reactivity theory, we examine the reactivity properties of this reaction system from three perspectives. These include scaling patterns of information-theoretic quantities such as Shannon entropy, Fisher information, Ghosh-Berkowitz-Parr entropy and information gain at both molecular and atomic levels, quantitative predictions of the barrier height with both Hirshfeld charge and information gain, and energetic decomposition analyses of the barrier height for the reactions. To that end, we focused in this work on the identity reaction of the monosubstituted-benzene molecule reacting with hydrogen fluoride using boron trifluoride as the catalyst in the gas phase. We also considered 19 substituting groups, 9 of which are ortho/para directing and the other 9 meta directing, besides the case of R = -H. Similar scaling patterns for these information-theoretic quantities found for stable species elsewhere were disclosed for these reactions systems. We also unveiled novel scaling patterns for information gain at the atomic level. The barrier height of the reactions can reliably be predicted by using both the Hirshfeld charge and information gain at the regioselective carbon atom. The energy decomposition analysis ensued yields an unambiguous picture about the origin of the barrier height, where we showed that it is the electrostatic interaction that plays the dominant role, while the roles played by exchange-correlation and

  3. Solid-phase synthesis of the non-calcium-binding loop of cod allergen M. Direct evidence of the reactivity of the amino-terminal segment.

    PubMed

    Elsayed, S; Ragnarsson, U; Netteland, B

    1983-03-01

    The synthesis of the non-calcium-binding AB loop of the assembly 13-32 of cod Allergen M (Mr 2122.1) was accomplished by solid-phase peptide synthesis. This peptide and the previously synthesized ones [12, 13, 14] have significant amino acid sequence homology. The synthetic crude preparation was obtained at relatively high recovery and purity. Further purification on a Bio-Gel P-2 column and a reversed-phase high-performance liquid chromatography column improved the grade of homogeneity, as demonstrated by high-voltage electrophoresis, end-terminal analysis, and amino acid composition. The peptide could, although to a much weaker extent than the intact Allergen M, directly bind IgE antibodies from the sera of cod-allergic individuals. At identical molar concentrations, a ratio of 1:6 for the in vitro reactivity of the peptide relative to the intact Allergen M was obtained. A similar reactivity was shown in the in vivo system used. The peptide also reacted with rabbit anti-Allergen M antibodies in rocket immunoelectrophoresis. The peptide appears to function as a divalent molecule in its primary interaction with antibodies.

  4. Formation and Reactivity of Organo-Functionalized Tin Selenide Clusters.

    PubMed

    Rinn, Niklas; Eußner, Jens P; Kaschuba, Willy; Xie, Xiulan; Dehnen, Stefanie

    2016-02-24

    Reactions of R(1) SnCl3 (R(1) =CMe2 CH2 C(O)Me) with (SiMe3 )2 Se yield a series of organo-functionalized tin selenide clusters, [(SnR(1) )2 SeCl4 ] (1), [(SnR(1) )2 Se2 Cl2 ] (2), [(SnR(1) )3 Se4 Cl] (3), and [(SnR(1) )4 Se6 ] (4), depending on the solvent and ratio of the reactants used. NMR experiments clearly suggest a stepwise formation of 1 through 4 by subsequent condensation steps with the concomitant release of Me3 SiCl. Furthermore, addition of hydrazines to the keto-functionalized clusters leads to the formation of hydrazone derivatives, [(Sn2 (μ-R(3) )(μ-Se)Cl4 ] (5, R(3) =[CMe2 CH2 CMe(NH)]2 ), [(SnR(2) )3 Se4 Cl] (6, R(2) =CMe2 CH2 C(NNH2 )Me), [(SnR(4) )3 Se4 ][SnCl3 ] (7, R(4) =CMe2 CH2 C(NNHPh)Me), [(SnR(2) )4 Se6 ] (8), and [(SnR(4) )4 Se6 ] (9). Upon treatment of 4 with [Cu(PPh3 )3 Cl] and excess (SiMe3 )2 Se, the cluster fragments to form [(R(1) Sn)2 Se2 (CuPPh3 )2 Se2 ] (10), the first discrete Sn/Se/Cu cluster compound reported in the literature. The derivatization reactions indicate fundamental differences between organotin sulfide and organotin selenide chemistry.

  5. The double life of a B-1 cell: self-reactivity selects for protective effector functions.

    PubMed

    Baumgarth, Nicole

    2011-01-01

    During their development, B and T cells with self-reactive antigen receptors are generally deleted from the repertoire to avoid autoimmune diseases. Paradoxically, innate-like B-1 cells in mice are positively selected for self-reactivity and form a pool of long-lived, self-renewing B cells that produce most of the circulating natural IgM antibodies. This Review provides an overview of the developmental processes that shape the B-1 cell pool in mice, outlines the functions of B-1 cells in both the steady state and during host defence, and discusses possible functional B-1 cell homologues that exist in humans.

  6. Synthesis and Use of Reactive Molecular Precursors for the Preparation of Carbon Nanomaterials

    NASA Astrophysics Data System (ADS)

    Schulte, Bjoern; Schrettl, Stephen; Frauenrath, Holger

    2017-02-01

    The use of reactive molecular carbon precursors is required if the preparation of carbon nanostructures and nanomaterials is to be achieved under conditions that are sufficiently benign to control their nanoscopic morphology and tailor their chemical functionalization. Recently, oligoyne precursors have been explored for this purpose, as they are sufficiently stable to be available in tangible quantities but readily rearrange in reactions that yield other forms of carbon. In this chapter, we briefly discuss available synthetic routes toward higher oligoynes that mostly rely on transition metal-mediated coupling reactions. Thereafter, a comprehensive overview of the use of oligoyne derivatives as precursors for carbon nanostructures and nanomaterials is given. While the non-templated conversion of simple oligoynes into carbonaceous matter exemplifies their potential as metastable carbon precursors, the more recent attempts to use functionalized oligoynes in host-guest complexes, self-assembled aggregates, thin films, colloids or other types of supramolecular structures have paved the way toward a new generation of carbon nanomaterials with predictable nanoscopic morphology and chemical functionalization.

  7. Alpha-tricalcium phosphate (α-TCP): solid state synthesis from different calcium precursors and the hydraulic reactivity.

    PubMed

    Cicek, Gulcin; Aksoy, Eda Ayse; Durucan, Caner; Hasirci, Nesrin

    2011-04-01

    The effects of solid state synthesis process parameters and primary calcium precursor on the cement-type hydration efficiency (at 37 °C) of α-tricalcium phosphate (Ca(3)(PO(4))(2) or α-TCP) into hydroxyapatite (Ca(10-x)HPO(4)(PO(4))(6-x)(OH)(2-x) x = 0-1, or HAp) have been investigated. α-TCP was synthesized by firing of stoichiometric amount of calcium carbonate (CaCO(3)) and monetite (CaHPO(4)) at 1150-1350 °C for 2 h. Three commercial grade CaCO(3) powders of different purity were used as the starting material and the resultant α-TCP products for all synthesis routes were compared in terms of the material properties and the reactivity. The reactant CaHPO(4) was also custom synthesized from the respective CaCO(3) source. A low firing temperature in the range of 1150-1350°C promoted formation of β-polymorph as a second phase in the resultant TCP. Meanwhile, higher firing temperatures resulted in phase pure α-TCP with poor hydraulic reactivity. The extension of firing operation also led to a decrease in the reactivity. It was found that identical synthesis history, morphology, particle size and crystallinity match between the α-TCPs produced from different CaCO(3) sources do not essentially culminate in products exhibiting similar hydraulic reactivity. The changes in reactivity are arising from differences in the trace amount of impurities found in the CaCO(3) precursors. In this regard, a correlation between the observed hydraulic reactivities and the impurity content of the CaCO(3) powders--as determined by inductively coupled plasma mass spectrometry--has been established. A high level of magnesium impurity in the CaCO(3) almost completely hampers the hydration of α-TCP. This impurity also favors formation of β- instead of α-polymorph in the product of TCP upon firing.

  8. Molecular architectures and functions of radical enzymes and their (re)activating proteins.

    PubMed

    Shibata, Naoki; Toraya, Tetsuo

    2015-10-01

    Certain proteins utilize the high reactivity of radicals for catalysing chemically challenging reactions. These proteins contain or form a radical and therefore named 'radical enzymes'. Radicals are introduced by enzymes themselves or by (re)activating proteins called (re)activases. The X-ray structures of radical enzymes and their (re)activases revealed some structural features of these molecular apparatuses which solved common enigmas of radical enzymes—i.e. how the enzymes form or introduce radicals at the active sites, how they use the high reactivity of radicals for catalysis, how they suppress undesired side reactions of highly reactive radicals and how they are (re)activated when inactivated by extinction of radicals. This review highlights molecular architectures of radical B12 enzymes, radical SAM enzymes, tyrosyl radical enzymes, glycyl radical enzymes and their (re)activating proteins that support their functions. For generalization, comparisons of the recently reported structures of radical enzymes with those of canonical radical enzymes are summarized here.

  9. Prenatal drug exposure moderates the association between stress reactivity and cognitive function in adolescence.

    PubMed

    Buckingham-Howes, Stacy; Bento, Samantha P; Scaletti, Laura A; Koenig, James I; Granger, Douglas A; Black, Maureen M

    2014-01-01

    Prenatal drug exposure (PDE) can undermine subsequent health and development. In a prospective longitudinal study we examine whether PDE moderates the link between stress reactivity and cognitive functioning in adolescence. Participants were 76 prenatally drug-exposed and 61 nonexposed (NE) community comparison African American youth (50% male, mean age 14.17 years) living in an urban setting. All participants completed neuropsychological and academic achievement tests (Children's Memory Scales, the California Verbal Learning Test - Children's version and the Wide Range Achievement Test 4) over the course of 1 day in a laboratory setting. Two mild stressors (Balloon Analog Risk Task - Youth and Behavioral Indicator of Resilience to Distress) were administered, with saliva samples (assayed for cortisol) collected pre- and poststress task. A higher percentage in the NE group, compared to the PDE group (26% vs. 12%, χ(2) = 4.70, d.f. = 1, n = 137, p = 0.03), exhibited task-related increases in salivary cortisol. PDE moderated the association between stress reactivity and 11 of 15 cognitive performance scales. In each case, the NE stress reactive group had better cognitive performance than either the NE lower cortisol reactive group or the PDE group regardless of stress reactivity status. Stress-related reactivity and regulation of the hypothalamic-pituitary-adrenal axis in adolescence may be disrupted by PDE, and the disruption may be linked to lower cognitive performance.

  10. Chemically Adjusting Plasma Temperature, Energy and Reactivity (CAPTEAR) Method Using NOx and Combustion for Selective Synthesis of Sc3N@C80 Metallic Nitride Fullerenes

    PubMed Central

    Stevenson, Steven; Thompson, M. Corey; Coumbe, H. Louie; Mackey, Mary A.; Coumbe, Curtis E.; Phillips, J. Paige

    2008-01-01

    Goals are (1) to selectively synthesize MNFs in lieu of empty-cage fullerenes (e.g., C60, C70) without compromising MNF yield and (2) to test our hypothesis that MNFs possess a different set of optimal formation parameters than empty-cage fullerenes. In this work, we introduce a novel approach for the selective synthesis of metallic nitride fullerenes (MNFs). This new method is “Chemically Adjusting Plasma Temperature, Energy and Reactivity” (CAPTEAR). The CAPTEAR approach with copper nitrate hydrate uses NOx vapor from NOx generating solid reagents, air and combustion to “tune” the temperature, energy and reactivity of the plasma environment. The extent of temperature, energy and reactive environment is stoichiometrically varied until optimal conditions for selective MNF synthesis are achieved. Analysis of soot extracts indicate that percentages of C60 and Sc3N@C80 are inversely related, whereas the percentages of C70 and higher empty-cage C2n fullerenes are largely unaffected. Hence, there may be a “competitive link” in the formation and mechanism of C60 and Sc3N@C80. Using this CAPTEAR method, purified MNFs (96% Sc3N@C80, 12 mg) have been obtained in soot extracts without a significant penalty in milligram yield when compared to control soot extracts (4% Sc3N@C80, 13 mg Sc3N@C80). The CAPTEAR process with Cu(NO3)2·2.5 H2O uses an exothermic nitrate moiety to suppress empty-cage fullerene formation, whereas Cu functions as a catalyst additive to offset the reactive plasma environment and boost the Sc3N@C80 MNF production. PMID:18052069

  11. Tuning the reactivity of semiconductor surfaces by functionalization with amines of different basicity

    PubMed Central

    Bent, Stacey F.; Kachian, Jessica S.; Rodríguez-Reyes, Juan Carlos F.; Teplyakov, Andrew V.

    2011-01-01

    Surface functionalization of semiconductors has been the backbone of the newest developments in microelectronics, energy conversion, sensing device design, and many other fields of science and technology. Over a decade ago, the notion of viewing the surface itself as a chemical reagent in surface reactions was introduced, and adding a variety of new functionalities to the semiconductor surface has become a target of research for many groups. The electronic effects on the substrate have been considered as an important consequence of chemical modification. In this work, we shift the focus to the electronic properties of the functional groups attached to the surface and their role on subsequent reactivity. We investigate surface functionalization of clean Si(100)-2 × 1 and Ge(100)-2 × 1 surfaces with amines as a way to modify their reactivity and to fine tune this reactivity by considering the basicity of the attached functionality. The reactivity of silicon and germanium surfaces modified with ethylamine (CH3CH2NH2) and aniline (C6H5NH2) is predicted using density functional theory calculations of proton attachment to the nitrogen of the adsorbed amine to differ with respect to a nucleophilic attack of the surface species. These predictions are then tested using a model metalorganic reagent, tetrakis(dimethylamido)titanium (((CH3)2N)4Ti, TDMAT), which undergoes a transamination reaction with sufficiently nucleophilic amines, and the reactivity tests confirm trends consistent with predicted basicities. The identity of the underlying semiconductor surface has a profound effect on the outcome of this reaction, and results comparing silicon and germanium are discussed. PMID:21068370

  12. Phosphorylcholine functionalized dendrimers for the formation of highly stable and reactive gold nanoparticles and their glucose conjugation for biosensing

    NASA Astrophysics Data System (ADS)

    Jia, Lan; Lv, Li-Ping; Xu, Jian-Ping; Ji, Jian

    2011-09-01

    Phosphorylcholine (PC)-functionalized poly(amido amine) (PAMAM) dendrimers were prepared and used as both reducing and stabilizing agents for synthesis of highly stable and reactive gold nanoparticles (Au NPs). Biomimetic PC-functionalized PAMAM dendrimers-stabilized gold nanoparticles (Au DSNPs) were formed by simply mixing the PC modified amine-terminated fifth-generation PAMAM dendrimers (G5-PC) with AuCl4 - ions by controlling the pH, no additional reducing agents or other stabilizers were needed. The obtained Au DSNPs were shown to be spherical, with particle diameters ranging from 5 to 12 nm, the sizes and growth kinetics of Au DSNPs could be tuned by changing the pH and the initial molar ratio of dendrimers to gold as indicated by transmission electron microscopy (TEM) and UV-Vis data. The prepared Au DSNPs showed excellent stability including: (1) stable at wide pH (7-13) values; (2) stable at high salt concentrations up to 2 M NaCl; (3) non-specific protein adsorption resistance. More importantly, surface functionalization could be performed by introducing desired functional groups onto the remained reactive amine groups. This was exemplified by the glucose conjugation. The glucose conjugated Au DSNPs showed bio-specific interaction with Concanavalin A (Con A), which induced aggregation of the Au NPs. Colorimetric detection of Con A based on the plasmon resonance of the glucose conjugated Au DSNPs was realized. A limit of detection (LOD) for Con A was 0.6 μM, based on a signal-to-noise ratio (S/N) of 3. These findings demonstrated that the PC modified Au DSNPs could potentially serve as a versatile nano-platform for the biomedical applications.

  13. Emotional Reactivity and Regulation in Infancy Interact to Predict Executive Functioning in Early Childhood

    ERIC Educational Resources Information Center

    Ursache, Alexandra; Blair, Clancy; Stifter, Cynthia; Voegtline, Kristin

    2013-01-01

    The relation of observed emotional reactivity and regulation in infancy to executive function in early childhood was examined in a prospective longitudinal sample of 1,292 children from predominantly low-income and rural communities. Children participated in a fear eliciting task at ages 7, 15, and 24 months and completed an executive function…

  14. Emotional Reactivity and Regulation in Infancy Interact to Predict Executive Functioning in Early Childhood

    ERIC Educational Resources Information Center

    Ursache, Alexandra; Blair, Clancy; Stifter, Cynthia; Voegtline, Kristin

    2013-01-01

    The relation of observed emotional reactivity and regulation in infancy to executive function in early childhood was examined in a prospective longitudinal sample of 1,292 children from predominantly low-income and rural communities. Children participated in a fear eliciting task at ages 7, 15, and 24 months and completed an executive function…

  15. Cortisol Reactivity is Positively Related to Executive Function in Preschool Children Attending Head Start

    ERIC Educational Resources Information Center

    Blair, Clancy; Granger, Douglas; Razza, Rachel Peters

    2005-01-01

    This study examined relations among cortisol reactivity and measures of cognitive function and social behavior in 4- to 5-year-old children (N=169) attending Head Start. Saliva samples for the assay of cortisol were collected at the beginning, middle, and end of an approximately 45-min testing session. Moderate increase in cortisol followed by…

  16. Reflective Functioning, Physiological Reactivity, and Overcontrol in Mothers: Links with School-Aged Children's Reflective Functioning

    ERIC Educational Resources Information Center

    Borelli, Jessica L.; Hong, Kajung; Rasmussen, Hannah F.; Smiley, Patricia A.

    2017-01-01

    Theorists argue that parental reflective functioning (PRF) is activated in response to emotions, potentially supporting parenting sensitivity even when arousal is high. That is, when parents become emotionally reactive when interacting with their children, those who can use PRF to understand their children's mental states should be able to parent…

  17. Titanium hydrazido and imido complexes: synthesis, structure, reactivity, and relevance to alkyne hydroamination.

    PubMed

    Li, Yahong; Shi, Yanhui; Odom, Aaron L

    2004-02-18

    Treatment of Ti(NMe(2))(2)(dpma) (1) with aniline results in the protonation of the dimethylamido ligands, which are retained as dimethylamines, and generation of a titanium imido complex Ti(NPh)(NHMe(2))(2)(dpma) (2) in 94% yield. The monomeric imido 2 is converted to the reactive dimeric micro-imido [Ti(NPh)(dpma)](2) (3) on removal of the labile dimethylamine donors. The dimer 3 is converted to monomeric terminal imido complexes in the presence of added donors, e.g., 4,4'-di-tert-butyl-2,2'-bipyridine (Bu(t)-bpy) and DME. Compounds 1-3 exhibit the same rate constant for 1-phenylpropyne hydroamination by aniline and are all kinetically competent to be involved in the catalytic cycle. Attempts to use 1 as a catalyst for hydroaminations involving 1,1-dimethylhydrazine resulted in only a few turnovers under the best conditions. Consequently, the chemistry of 1 with hydrazines to generate hydrazido complexes was scrutinized for comparison with the imido species. Through these studies, titanium hydrazido complexes including Ti(eta(2)-NHNC(5)H(10))(2)(dpma) (5), Ti(eta(2)-NHNMe(2))(2)(dpma) (6), and [Ti(micro:eta(1),eta(2)-NNMe(2))(dpma)](2) (7) were characterized. In addition, a terminal hydrazido(2-) complex was available by addition of Bu(t)-bpy to 1 prior to 1,1-dimethylhydrazine addition, which provided Ti(eta(1)-NNMe(2))(Bu(t)-bpy)(dpma) (8). Compound 8 was structurally characterized and compared to Ti(NPh)(Bu(t)-bpy)(dpma) (4b), an imido derivative with the same ancillary ligand set. Compound 8 has a nucleophilic beta-nitrogen consistent with a hydrazido(2-) formulation, as determined by reaction with MeI to form the ammonium imido complex [Ti(NNMe(3))(Bu(t)-bpy)(dpma)]I (9). Analogous pyridinium imido complexes [Ti(N-1-pyridinium)(Bu(t)-bpy)(dpma)](+) (10) are available by addition of 1-aminopyridinium iodide to 1. From the investigations, some conclusions regarding the activity of titanium pyrrolyl complexes in hydroamination were drawn. The lack of conversion

  18. Synthesis of SiC/Ag/Cellulose Nanocomposite and Its Antibacterial Activity by Reactive Oxygen Species Generation

    PubMed Central

    Borkowski, Andrzej; Cłapa, Tomasz; Szala, Mateusz; Gąsiński, Arkadiusz; Selwet, Marek

    2016-01-01

    We describe the synthesis of nanocomposites, based on nanofibers of silicon carbide, silver nanoparticles, and cellulose. Silver nanoparticle synthesis was achieved with chemical reduction using hydrazine by adding two different surfactants to obtain a nanocomposite with silver nanoparticles of different diameters. Determination of antibacterial activity was based on respiration tests. Enzymatic analysis indicates oxidative stress, and viability testing was conducted using an epifluorescence microscope. Strong bactericidal activity of nanocomposites was found against bacteria Escherichia coli and Bacillus cereus, which were used in the study as typical Gram-negative and Gram-positive bacteria, respectively. It is assumed that reactive oxygen species generation was responsible for the observed antibacterial effect of the investigated materials. Due to the properties of silicon carbide nanofiber, the obtained nanocomposite may have potential use in technology related to water and air purification. Cellulose addition prevented silver nanoparticle release and probably enhanced bacterial adsorption onto aggregates of the nanocomposite material. PMID:28335299

  19. Organometallic synthesis, reactivity and catalysis in the solid state using well-defined single-site species

    PubMed Central

    Pike, Sebastian D.; Weller, Andrew S.

    2015-01-01

    Acting as a bridge between the heterogeneous and homogeneous realms, the use of discrete, well-defined, solid-state organometallic complexes for synthesis and catalysis is a remarkably undeveloped field. Here, we present a review of this topic, focusing on describing the key transformations that can be observed at a transition-metal centre, as well as the use of well-defined organometallic complexes in the solid state as catalysts. There is a particular focus upon gas–solid reactivity/catalysis and single-crystal-to-single-crystal transformations. PMID:25666064

  20. Visible light mediated fast iterative RAFT synthesis of amino-based reactive copolymers in water at 20 °C.

    PubMed

    Tong, Jianyu; Shi, Yi; Liu, Guhuan; Huang, Tao; Xu, Na; Zhu, Zhengguang; Cai, Yuanli

    2013-12-01

    The attempts to mediate iterative RAFT polymerization of ionic monomers through visible light irradiation in water at 20 °C is reported, in which complete conversions are attained in several tens of minutes and the propagation suspends/restarts immediately for multiple times on cycling irradiation. This technique suits the one-pot synthesis of NH2 /imidazole-based polymers with tuned structures from homo to random, block, random-block, and block-random-block, thus is robust and promising to control the sequence of the ionized water-soluble reactive copolymers.

  1. Clear microstructure-performance relationships in Mn-containing perovskite and hexaaluminate compounds prepared by activated reactive synthesis.

    PubMed

    Laassiri, Said; Bion, Nicolas; Duprez, Daniel; Royer, Sébastien; Alamdari, Houshang

    2014-03-07

    Microstructural properties of mixed oxides play essential roles in their oxygen mobility and consequently in their catalytic performances. Two families of mixed oxides (perovskite and hexaaluminate) with different microstructural features, such as crystal size and specific surface area, were prepared using the activated reactive synthesis (ARS) method. It was shown that ARS is a flexible route to synthesize both mixed oxides with nano-scale crystal size and high specific surface area. Redox properties and oxygen mobility were found to be strongly affected by the material microstructure. Catalytic activities of hexaaluminate and perovskite materials for methane oxidation were discussed in the light of structural, redox and oxygen mobility properties.

  2. New one-pot synthesis of Au and Ag nanoparticles using green rust reactive particle as a micro-reactor

    NASA Astrophysics Data System (ADS)

    Ayadi, Sondra; Perca, Cristian; Legrand, Ludovic

    2013-02-01

    A new, simple, and fast one-pot synthesis of supported Au or Ag nanoparticles is implemented, for which a reactive Fe(II)-bearing green rust inorganic particle is used as an individual micro-reactor acting as both the reducing agent and support for the resulting metal nanoparticles. The mechanism involves both the solid-state oxidation of the green rust support (sulfate or carbonate) and the reduction-precipitation of soluble metal precursor. The resulting nanohybrids have a platy inorganic part supporting about one to ten nanoparticles with sizes in the 20 to 120 nm range.

  3. Reactive superhydrophobic surface and its photoinduced disulfide-ene and thiol-ene (bio)functionalization.

    PubMed

    Li, Junsheng; Li, Linxian; Du, Xin; Feng, Wenqian; Welle, Alexander; Trapp, Oliver; Grunze, Michael; Hirtz, Michael; Levkin, Pavel A

    2015-01-14

    Reactive superhydrophobic surfaces are highly promising for biotechnological, analytical, sensor, or diagnostic applications but are difficult to realize due to their chemical inertness. In this communication, we report on a photoactive, inscribable, nonwettable, and transparent surface (PAINTS), prepared by polycondensation of trichlorovinylsilane to form thin transparent reactive porous nanofilament on a solid substrate. The PAINTS shows superhydrophobicity and can be conveniently functionalized with the photoclick thiol-ene reaction. In addition, we show for the first time that the PAINTS bearing vinyl groups can be easily modified with disulfides under UV irradiation. The effect of superhydrophobicity of PAINTS on the formation of high-resolution surface patterns has been investigated. The developed reactive superhydrophobic coating can find applications for surface biofunctionalization using abundant thiol or disulfide bearing biomolecules, such as peptides, proteins, or antibodies.

  4. Impact of Lewis acids on Diels-Alder reaction reactivity: a conceptual density functional theory study.

    PubMed

    Xia, Yue; Yin, Dulin; Rong, Chunying; Xu, Qiong; Yin, Donghong; Liu, Shubin

    2008-10-09

    Density functional theory (DFT) and conceptual/chemical DFT studies are carried out in this work for the normal electron demand Diels-Alder reaction between isoprene and acrolein to compare chemical reactivity and regioselectivity of the reactants in the absence and presence of Lewis acid (LA) catalysts. A cyclic coplanar structure of acrolein-LA complex has been observed and the natural bond orbital analysis has been employed to interpret the interaction between acrolein and LAs. Reactivity indices from frontier molecular orbital energies are proved to be adequate and efficient to evaluate the catalytic property of LAs. Linear relationships have been discovered among the bond order, bond length, catalytic activation, and chemical reactivity for the systems concerned. The validity and applicability of maximum hardness principle, minimum polarizability principle, and minimum electrophilicity principle are examined and discussed in the prediction of the major regioselective isomer and the preferred reaction pathway for the reactions in the present study.

  5. Density functional study of reactivity and regioselectivity of H2O C60

    NASA Astrophysics Data System (ADS)

    KC, Govinda Bahadur

    The exohedral reactivity of endohedral fullerene has aroused significant interest because of its potential applications in biology, medicine and material science. The encapsulation of a single water molecule without any hydrogen bonding to other compounds, inside the hydrophobic environment of C60 is an intriguing topic to study about. In 2011, Kurotobi and Murata successfully synthesized H2O C60 fullerene. The presence of a polar water molecule inside the cage is expected to cause changes in the exohedral reactivity of C60. In order to find out the impact of an entrapped single water molecule on the reactivity of C60 fullerene, we use density functional theory to study the thermodynamics and kinetics of [4+2] Diels-Alder reaction of 1, 3 cis butadiene at all non-identical bonds of free C60 and H2O C60. Our calculations show that the encapsulation of a single water molecule does not have any significant effect on the exohedral reactivity compared to free C60. Moreover, the obtained reaction energies and activation barriers indicate that [6, 6] bond is more reactive than [5, 6] bond and thus cycloaddition is clearly favored at [6, 6] bond. The dipole moment of the H2O C60 is only 0.48 Debye significantly smaller than that of water molecule. The infrared and Raman spectra of the endohedral fullerene are also computed.

  6. Function of reactive oxygen species during animal development: passive or active?

    PubMed

    Covarrubias, Luis; Hernández-García, David; Schnabel, Denhí; Salas-Vidal, Enrique; Castro-Obregón, Susana

    2008-08-01

    Oxidative stress is considered causal of aging and pathological cell death, however, very little is known about its function in the natural processes that support the formation of an organism. It is generally thought that cells must continuously protect themselves from the possible damage caused by reactive oxygen species (ROS) (passive ROS function). However, presently, ROS are recognized as physiologically relevant molecules that mediate cell responses to a variety of stimuli, and the activities of several molecules, some developmentally relevant, are directly or indirectly regulated by oxidative stress (active ROS function). Here we review recent data that are suggestive of specific ROS functions during development of animals, particularly mammals.

  7. Mechanistic approaches to the study of evolution: the functional synthesis.

    PubMed

    Dean, Antony M; Thornton, Joseph W

    2007-09-01

    An emerging synthesis of evolutionary biology and experimental molecular biology is providing much stronger and deeper inferences about the dynamics and mechanisms of evolution than were possible in the past. The new approach combines statistical analyses of gene sequences with manipulative molecular experiments to reveal how ancient mutations altered biochemical processes and produced novel phenotypes. This functional synthesis has set the stage for major advances in our understanding of fundamental questions in evolutionary biology. Here we describe this emerging approach, highlight important new insights that it has made possible, and suggest future directions for the field.

  8. Resting state functional connectivity within the cingulate cortex jointly predicts agreeableness and stressor-evoked cardiovascular reactivity.

    PubMed

    Ryan, John P; Sheu, Lei K; Gianaros, Peter J

    2011-03-01

    Exaggerated cardiovascular reactivity to stress is a risk factor for cardiovascular disease. Further, individual differences in stressor-evoked cardiovascular reactivity covary with the functionality of corticolimbic brain systems, particularly areas of the cingulate cortex. What remains unclear, however, is how individual differences in personality traits interact with cingulate functionality in the prediction of stressor-evoked cardiovascular reactivity. Accordingly, we tested the associations between (i) a particular personality trait, Agreeableness, which is associated with emotional reactions to conflict, (ii) resting state functional connectivity within the cingulate cortex, and (iii) stressor-evoked blood pressure (BP) reactivity. Participants (N=39, 19 men, aged 20-37 years) completed a resting functional connectivity MRI protocol, followed by two standardized stressor tasks that engaged conflict processing and evoked BP reactivity. Agreeableness covaried positively with BP reactivity across individuals. Moreover, connectivity analyses demonstrated that a more positive functional connectivity between the posterior cingulate (BA31) and the perigenual anterior cingulate (BA32) covaried positively with Agreeableness and with BP reactivity. Finally, statistical mediation analyses demonstrated that BA31-BA32 connectivity mediated the covariation between Agreeableness and BP reactivity. Functional connectivity within the cingulate appears to link Agreeableness and a risk factor for cardiovascular disease, stressor-evoked BP reactivity.

  9. Dual-Functional Hydrazide-Reactive and Anhydride-Containing Oligomeric Hydrogel Building Blocks.

    PubMed

    Kascholke, Christian; Loth, Tina; Kohn-Polster, Caroline; Möller, Stephanie; Bellstedt, Peter; Schulz-Siegmund, Michaela; Schnabelrauch, Matthias; Hacker, Michael C

    2017-03-13

    Biomimetic hydrogels are advanced biomaterials that have been developed following different synthetic routes. Covalent postfabrication functionalization is a promising strategy to achieve efficient matrix modification decoupled of general material properties. To this end, dual-functional macromers were synthesized by free radical polymerization of maleic anhydride with diacetone acrylamide (N-(1,1-dimethyl-3-oxobutyl)acrylamide) and pentaerythritol diacrylate monostearate. Amphiphilic oligomers (Mn < 7.5 kDa) with anhydride contents of 7-20% offered cross-linking reactivity to yield rigid hydrogels with gelatinous peptides (E = 4-13 kPa) and good cell adhesion properties. Mildly reactive methyl ketones as second functionality remained intact during hydrogel formation and potential of covalent matrix modification was shown using hydrazide and hydrazine model compounds. Successful secondary dihydrazide cross-linking was demonstrated by an increase of hydrogel stiffness (>40%). Efficient hydrazide/hydrazine immobilization depending on solution pH, hydrogel ketone content as well as ligand concentration for bioconjugation was shown and reversibility of hydrazone formation was indicated by physiologically relevant hydrazide release over 7 days. Proof-of-concept experiments with hydrazido-functionalized hyaluronan demonstrated potential for covalent aECM immobilization. The presented dual-functional macromers have perspective as reactive hydrogel building blocks for various biomedical applications.

  10. Forward and reverse transfer function model synthesis

    NASA Technical Reports Server (NTRS)

    Houghton, J. R.

    1985-01-01

    A process for synthesizing a mathematical model for a linear mechanical system using the forward and reverse Fourier transform functions is described. The differential equation for a system model is given. The Bode conversion of the differential equation, and the frequency and time-domain optimization matching of the model to the forward and reverse transform functions using the geometric simplex method of Nelder and Mead (1965) are examined. The effect of the window function on the linear mechanical system is analyzed. The model is applied to two examples; in one the signal damps down before the end of the time window and in the second the signal has significant energy at the end of the time window.

  11. Forward and reverse transfer function model synthesis

    NASA Technical Reports Server (NTRS)

    Houghton, J. R.

    1985-01-01

    A process for synthesizing a mathematical model for a linear mechanical system using the forward and reverse Fourier transform functions is described. The differential equation for a system model is given. The Bode conversion of the differential equation, and the frequency and time-domain optimization matching of the model to the forward and reverse transform functions using the geometric simplex method of Nelder and Mead (1965) are examined. The effect of the window function on the linear mechanical system is analyzed. The model is applied to two examples; in one the signal damps down before the end of the time window and in the second the signal has significant energy at the end of the time window.

  12. Dispositional Mindfulness Uncouples Physiological and Emotional Reactivity to a Laboratory Stressor and Emotional Reactivity to Executive Functioning Lapses in Daily Life.

    PubMed

    Feldman, Greg; Lavalle, Jayne; Gildawie, Kelsea; Greeson, Jeffrey M

    2016-04-01

    Both dispositional mindfulness and mindfulness training may help to uncouple the degree to which distress is experienced in response to aversive internal experience and external events. Because emotional reactivity is a transdiagnostic process implicated in numerous psychological disorders, dispositional mindfulness and mindfulness training could exert mental health benefits, in part, by buffering emotional reactivity. The present studies examine whether dispositional mindfulness moderates two understudied processes in stress reactivity research: the degree of concordance between subjective and physiological reactivity to a laboratory stressor (Study 1); and the degree of dysphoric mood reactivity to lapses in executive functioning in daily life (Study 2). In both studies, lower emotional reactivity to aversive experiences was observed among individuals scoring higher in mindfulness, particularly non-judging, relative to those scoring lower in mindfulness. These findings support the hypothesis that higher dispositional mindfulness fosters lower emotional reactivity. Results are discussed in terms of implications for applying mindfulness-based interventions to a range of psychological disorders in which people have difficulty regulating emotional reactions to stress.

  13. Dispositional Mindfulness Uncouples Physiological and Emotional Reactivity to a Laboratory Stressor and Emotional Reactivity to Executive Functioning Lapses in Daily Life

    PubMed Central

    Feldman, Greg; Lavalle, Jayne; Gildawie, Kelsea; Greeson, Jeffrey M.

    2016-01-01

    Both dispositional mindfulness and mindfulness training may help to uncouple the degree to which distress is experienced in response to aversive internal experience and external events. Because emotional reactivity is a transdiagnostic process implicated in numerous psychological disorders, dispositional mindfulness and mindfulness training could exert mental health benefits, in part, by buffering emotional reactivity. The present studies examine whether dispositional mindfulness moderates two understudied processes in stress reactivity research: the degree of concordance between subjective and physiological reactivity to a laboratory stressor (Study 1); and the degree of dysphoric mood reactivity to lapses in executive functioning in daily life (Study 2). In both studies, lower emotional reactivity to aversive experiences was observed among individuals scoring higher in mindfulness, particularly non-judging, relative to those scoring lower in mindfulness. These findings support the hypothesis that higher dispositional mindfulness fosters lower emotional reactivity. Results are discussed in terms of implications for applying mindfulness-based interventions to a range of psychological disorders in which people have difficulty regulating emotional reactions to stress. PMID:27087863

  14. mu-opioid receptor-stimulated synthesis of reactive oxygen species is mediated via phospholipase D2.

    PubMed

    Koch, Thomas; Seifert, Anja; Wu, Dai-Fei; Rankovic, Marija; Kraus, Jürgen; Börner, Christine; Brandenburg, Lars-Ove; Schröder, Helmut; Höllt, Volker

    2009-08-01

    We have recently shown that the activation of the rat mu-opioid receptor (MOPr, also termed MOR1) by the mu-agonist [D-Ala(2), Me Phe(4), Glyol(5)]enkephalin (DAMGO) leads to an increase in phospholipase D2 (PLD2) activity and an induction of receptor endocytosis, whereas the agonist morphine which does not induce opioid receptor endocytosis fails to activate PLD2. We report here that MOPr-mediated activation of PLD2 stimulates production of reactive oxygen molecules via NADH/NADPH oxidase. Oxidative stress was measured with the fluorescent probe dichlorodihydrofluorescein diacetate and the role of PLD2 was assessed by the PLD inhibitor D-erythro-sphingosine (sphinganine) and by PLD2-small interfering RNA transfection. To determine whether NADH/NADPH oxidase contributes to opioid-induced production of reactive oxygen species, mu-agonist-stimulated cells were pre-treated with the flavoprotein inhibitor, diphenylene iodonium, or the specific NADPH oxidase inhibitor, apocynin. Our results demonstrate that receptor-internalizing agonists (like DAMGO, beta-endorphin, methadone, piritramide, fentanyl, sufentanil, and etonitazene) strongly induce NADH/NADPH-mediated ROS synthesis via PLD-dependent signaling pathways, whereas agonists that do not induce MOPr endocytosis and PLD2 activation (like morphine, buprenorphine, hydromorphone, and oxycodone) failed to activate ROS synthesis in transfected human embryonic kidney 293 cells. These findings indicate that the agonist-selective PLD2 activation plays a key role in the regulation of NADH/NADPH-mediated ROS formation by opioids.

  15. Effects of protein synthesis inhibitors during reactivation of associative memory in the common snail induces reversible and irreversible amnesia.

    PubMed

    Solntseva, S V; Nikitin, V P; Kozyrev, S A; Shevelkin, A V; Lagutin, A V; Sherstnev, V V

    2007-11-01

    The effects of protein synthesis inhibitors on the reactivation of an associative skill consisting of refusing a particular food by common snails were studied. Animals were given single injections of a protein synthesis inhibitor (cycloheximide at 0.6 mg/snail or anisomycin at 0.4 mg) 24 h after three days of training, and were then presented with a "reminding" stimulus (the "conditioned reflex" food-banana) and tested for retention of the skill. Observations revealed an impairment of reproduction of the acquired skill 2.5 h after the "reminder," with spontaneous restoration at 4.5-5.5 h. Other snails were given single 1.8-mg doses of cycloheximide or three 0.6-mg doses with intervals of 2 h. "Reminders" were presented after each injection. In these conditions, impairment of reproduction of the conditioned reflex also appeared 2.5 h after the first "reminder," though amnesia lasted at least 30 days and repeat training of the animals produced only partial recovery of the skill. Thus, we have provided the first demonstration that recovery of a long-term memory "trace" on exposure to relatively low doses of protein synthesis inhibitors produces transient and short-lived amnesia, lasting 2-3 h, while long-term, irreversible amnesia occurs after longer-lasting or more profound suppression of protein synthesis. These results suggest that the "reminding" process induces reconsolidation of the " initial" memory, suppression of which by protein synthesis inhibitors leads to "erasure" of the memory "trace" and impairs consolidation on repeat training.

  16. Scalable synthesis and functionalization of cobalt nanoparticles for versatile magnetic separation and metal adsorption

    NASA Astrophysics Data System (ADS)

    Mattila, Pipsa; Heinonen, Hanna; Loimula, Kalle; Forsman, Johanna; Johansson, Leena-Sisko; Tapper, Unto; Mahlberg, Riitta; Hentze, Hans-Peter; Auvinen, Ari; Jokiniemi, Jorma; Milani, Roberto

    2014-09-01

    Magnetic cobalt nanoparticles coated with a thin carbon shell were produced by means of a scalable method based on hydrogen reduction synthesis. The presence of oxidized groups on the surface of the carbon shell enabled the reaction with alkoxysilanes bearing amino and thiol reactive functions under mild conditions, and therefore the formation of a thin functional silane layer which holds the potential for further modification in consideration of specific applications, e.g., in the separation and catalysis fields. The magnetic nanoparticles bearing surface thiol groups were also used in metal adsorption tests. These nanoparticles could efficiently adsorb not only gold from a chloride salt aqueous solution, but also several other metals when incubated in a thiocyanate-leached solution obtained from crushed printed circuit boards. The combination of a scalable production method with a simple and versatile surface modification strategy opens up a wide array of potential industrial applications in the fields of separation, sensing, and biomedical devices.

  17. Design, synthesis, and characterization of novel, nonquaternary reactivators of GF-inhibited human acetylcholinesterase.

    PubMed

    McHardy, Stanton F; Bohmann, Jonathan A; Corbett, Michael R; Campos, Bismarck; Tidwell, Michael W; Thompson, Paul Marty; Bemben, Chris J; Menchaca, Tony A; Reeves, Tony E; Cantrell, William R; Bauta, William E; Lopez, Ambrosio; Maxwell, Donald M; Brecht, Karen M; Sweeney, Richard E; McDonough, John

    2014-04-01

    The goal of this research was to identify structurally novel, non-quaternarypyridinium reactivators of GF (cyclosarin)-inhibited hAChE that possess the capacity to mediate in vitro reactivation of GF-inhibited human acetylcholinesterase (hAChE). New compounds were designed, synthesized and assessed in GF-inhibited hAChE assays. Structure activity relationships for AChE binding and reactivation of GF-inhibited hAChE were developed. Lead compounds from two different chemical series, represented by compounds 17 and 38, displayed proficient in vitro reactivation of GF-inhibited hAChE, while also possessing low inhibition of native enzyme. Copyright © 2014 Elsevier Ltd. All rights reserved.

  18. A parametric transfer function methodology for analyzing reactive transport in nonuniform flow.

    PubMed

    Luo, Jian; Cirpka, Olaf A; Fienen, Michael N; Wu, Wei-min; Mehlhorn, Tonia L; Carley, Jack; Jardine, Philip M; Criddle, Craig S; Kitanidis, Peter K

    2006-02-01

    We analyze reactive transport during in-situ bioremediation in a nonuniform flow field, involving multiple extraction and injection wells, by the method of transfer functions. Gamma distributions are used as parametric models of the transfer functions. Apparent parameters of classical transport models may be estimated from those of the gamma distributions by matching temporal moments. We demonstrate the method by application to measured data taken at a field experiment on bioremediation conducted in a multiple-well system in Oak Ridge, TN. Breakthrough curves (BTCs) of a conservative tracer (bromide) and a reactive compound (ethanol) are measured at multi-level sampling (MLS) wells and in extraction wells. The BTCs of both compounds are jointly analyzed to estimate the first-order degradation rate of ethanol. To quantify the tracer loss, we compare the approaches of using a scaling factor and a first-order decay term. Results show that by including a scaling factor both gamma distributions and inverse-Gaussian distributions (transfer functions according to the advection-dispersion equation) are suitable to approximate the transfer functions and estimate the reactive rate coefficients for both MLS and extraction wells. However, using a first-order decay term for tracer loss fails to describe the BTCs at the extraction well, which is affected by the nonuniform distribution of travel paths.

  19. A parametric transfer function methodology for analyzing reactive transport in nonuniform flow

    SciTech Connect

    Jardine, Philip M; Cirpka, Olaf; Fienen, Michael; Wu, Weimin; Mehlhorn, Tonia L; Carley, Jack M; Criddle, Craig; Kitanidis, Peter K

    2005-12-01

    We analyze reactive transport during in-situ bioremediation in a nonuniform flow field, involving multiple extraction and injection wells, by the method of transfer functions. Gamma distributions are used as parametric models of the transfer functions. Apparent parameters of classical transport models may be estimated from those of the gamma distributions by matching temporal moments. We demonstrate the method by application to measured data taken at a field experiment on bioremediation conducted in a multiple-well system in Oak Ridge, TN. Breakthrough curves (BTCs) of a conservative tracer (bromide) and a reactive compound (ethanol) are measured at multi-level sampling (MLS) wells and in extraction wells. The BTCs of both compounds are jointly analyzed to estimate the first-order degradation rate of ethanol. To quantify the tracer loss, we compare the approaches of using a scaling factor and a first-order decay term. Results show that by including a scaling factor both gamma distributions and inverse-Gaussian distributions (transfer functions according to the advection-dispersion equation) are suitable to approximate the transfer functions and estimate the reactive rate coefficients for both MLS and extraction wells. However, using a first-order decay term for tracer loss fails to describe the BTCs at the extraction well, which is affected by the nonuniform distribution of travel paths.

  20. Examining Endothelial Function and Platelet Reactivity in Patients with Depression before and after SSRI Therapy

    PubMed Central

    Dawood, Tye; Barton, David A.; Lambert, Elisabeth A.; Eikelis, Nina; Lambert, Gavin W.

    2016-01-01

    Although it is recognized that patients with major depressive disorder (MDD) are at increased risk of developing cardiovascular disease (CVD) the mechanisms responsible remain unknown. Endothelial dysfunction is one of the first signs of CVD. Using two techniques, flow-mediated dilatation in response to reactive hyperemia and laser Doppler velocimetry with iontophoresis, we examined endothelial function in the forearm before and after serotonin-specific reuptake inhibitor (SSRI) treatment in 31 patients with MDD. Measurement of intercellular adhesion molecule-1, vascular cell adhesion molecule-1, soluble P-selectin, and noradrenaline in plasma was also performed. Prior to treatment, markers of endothelial and vascular function and platelet reactivity were within the normal range. Following SSRI therapy (95 ± 5 days) symptoms of depression were reduced (paired difference between pre- and post-treatment Hamilton rating −18 ± 1, P < 0.001) with 19 patients recovered and 4 remitted. There occurred no significant change in markers of endothelial or vascular function following SSRI therapy. The improvement in Hamilton depression rating in response to therapy could be independently predicted by the baseline arterial plasma noradrenaline concentration (r2 = 0.36, P = 0.003). In this cohort of patients with MDD, SSRI therapy did not influence endothelial function or markers of vascular or platelet reactivity. Patient response to SSRI therapy could be predicted by the initial circulating level of noradrenaline, with noradrenaline levels being lower in responders. PMID:26924994

  1. Synthesis and adsorption of functionalized polystyrenes

    SciTech Connect

    Iyengar, D.R.

    1992-12-31

    The effect of specifically interacting functional groups located at the chain ends of polystyrene on the absorption rate, adsorbance, graft density and surface excess are discussed from cyclohexane, a theta solvent and toluene. Polystyrenes with hydroxyl and carboxylic acid-end-groups in narrow molecular weight distribution are synthesized by anionic polymerization of styrene followed by suitable termination reactions. Thin layer chromatography (TLC) is developed as an analytical technique to predict trends in the adsorption of the polymers in a range of solvents. In particular the information about the localization of the end-group and therefore different chain architectures at the interface are inferred from this simple technique. Adsorption isotherms are obtained for each of the functionalized polymers of four different molecular weights, the selection of which was based on the TLC results. Kinetics of adsorption and the adsorbance data are determined by liquid counting of tritium labelled polymers. Graft density and surface excess data are calculated from the adsorbance data and other known parameters. It is shown, from these data, that polystyrenes with a carboxylic acid end-group form weakly stretched brushes at the glass-cyclohexane interface and mushrooms at the glass-toluene interface a result consistent with the higher osmotic repulsions towards packing in good solvents. Polystyrenes with function groups at both the chain ends are hypothesized to form a range of structures from those dominated by tails at higher concentrations to those dominated by loops and trains at lower solution concentrations. At higher molecular weights it is shown that functionalized a result consistent with the TLC predictions. Hydroxyl end-group is shown to be an ineffective sticky foot from its adsorbance vis-a-vis polystyrene.

  2. Acute functional reactivation of the language network during awake intraoperative brain mapping.

    PubMed

    Spena, Giannantonio; Costi, Emanuele; Panciani, Pier Paolo; Roca, Elena; Migliorati, Karol; Fontanella, Marco Maria

    2015-01-01

    Acute brain plasticity during resection of central lesions has been recently described. In the cases reported, perilesional latent networks, useful to preserve the neurological functions, were detected in asymptomatic patients. In this paper, we presented a case of acute functional reactivation (AFR) of the language network in a symptomatic patient. Tumor resection allowed to acutely restore the neurological deficit. Intraoperative direct cortical stimulation (DCS) and functional neuroimaging showed new epicentres of activation of the language network after tumor excision. DCS in awake surgery is mandatory to reveal AFR needful to improve the extent of resection preserving the quality of life.

  3. Predicting Chemical Reactivity from the Charge Density through Gradient Bundle Analysis: Moving beyond Fukui Functions.

    PubMed

    Morgenstern, Amanda; Wilson, Timothy R; Eberhart, M E

    2017-06-08

    Predicting chemical reactivity is a major goal of chemistry. Toward this end, atom condensed Fukui functions of conceptual density functional theory have been used to predict which atom is most likely to undergo electrophilic or nucleophilic attack, providing regioselectivity information. We show that the most probable regions for electrophilic attack within each atom can be predicted through analysis of gradient bundle volumes, a property that depends only on the charge density of the neutral molecules. We also introduce gradient bundle condensed Fukui functions to compare the stereoselectivity information obtained from gradient bundle volume analysis. We demonstrate this method using the test set of molecular fluorine, oxygen, nitrogen, carbon monoxide, and hydrogen cyanide.

  4. Toward the Synthesis of More Reactive S = 2 Non-Heme Oxoiron(IV) Complexes

    PubMed Central

    2016-01-01

    cleave substrate C–H bonds. The second strategy entailed introducing weaker-field equatorial ligands in six-coordinate oxoiron(IV) complexes to decrease the dx2–y2/dxy energy gap to the point where the S = 2 ground state is favored. These pseudo-octahedral S = 2 oxoiron(IV) complexes exhibit high H-atom transfer reactivity relative to their S = 1 counterparts and shed light on the role that the spin state may play in these reactions. Among these complexes is a highly reactive species that to date represents the closest electronic and functional model of the enzymatic intermediate, TauD-J. PMID:26176555

  5. Synthesis of Amide Functionalized Carbon Nanotubes

    DTIC Science & Technology

    2007-01-01

    amide-linked SWNTs. Through FT-IR spectroscopy, Raman spectroscopy and TGA analysis it was proven that the intermediate compounds were successfully...analysis (TGA). Figure 4 shows the TGA data for SWNT-COOH, SWNT-NH2 and SWNT 4 at a heating rate of 10 oC/min in the presence of argon. The TGA ... analysis shows a major decline in mass for the amide- interconnected nanotubes between the 200 oC to 400 oC region. Weight loss due to functionalization

  6. High-performance liquid chromatography analysis of by-products and intermediates arising during the synthesis of the acetylcholinesterase reactivator HI-6.

    PubMed

    Jun, Daniel; Stodulka, Petr; Kuca, Kamil; Dolezal, Bohuslav

    2010-09-01

    An high-performance liquid chromatography (HPLC) method for identification of quaternary and non-quaternary compounds (parent compounds, intermediates, by-products, and products) within the synthesis of the acetylcholinesterase reactivator HI-6, the most promising antidote of nerve agent poisonings, is described. This HPLC method could be of high interest as a quick purity control for those who are interested in development of new acetylcholinesterase reactivators as well as for those who are interested in the synthesis of HI-6 in laboratory or in large-scale production. An HPLC method for quaternary compounds without using common ion-pairing reagents was developed, too.

  7. Synthesis of the kyotorphin precursor benzoyl-L-tyrosine-L-argininamide with immobilized α-chymotrypsin in sequential batch with enzyme reactivation.

    PubMed

    Bahamondes, Carola; Wilson, Lorena; Bernal, Claudia; Illanes, Andrés; Álvaro, Gregorio; Guzmán, Fanny

    2016-01-01

    α-Chymotrypsin was immobilized in activated agarose support and the stability of the biocatalyst was assessed in three polar organic solvents, namely, ethanol, diglyme, and acetonitrile. Ethanol was the solvent in which the stability of the enzyme was higher and was then selected to perform the synthesis of the kyotorphin derivative benzoyl-tyrosine argininamide, evaluating enzyme reactivation after synthesis. Substrates for reaction were benzoyl tyrosine ethyl ester and argininamide, the reaction being performed under kinetic control. High conversion yield (85%) was obtained and the immobilized enzyme was successfully used in sequential batch reactor operation with enzyme reactivation after three batches. © 2015 American Institute of Chemical Engineers.

  8. Terminal Titanyl Complexes of Tri- and Tetrametaphosphate: Synthesis, Structures, and Reactivity with Hydrogen Peroxide.

    PubMed

    Stauber, Julia M; Cummins, Christopher C

    2017-03-06

    The synthesis and characterization of tri- and tetrametaphosphate titanium(IV) oxo and peroxo complexes is described. Addition of 0.5 equiv of [OTi(acac)2]2 to dihydrogen tetrametaphosphate ([P4O12H2](2-)) and monohydrogen trimetaphosphate ([P3O9H](2-)) provided a bis(μ2,κ(2),κ(2)) tetrametaphosphate titanyl dimer, [OTiP4O12]2(4-) (1; 70% yield), and a trimetaphosphate titanyl acetylacetonate complex, [OTiP3O9(acac)](2-) (2; 59% yield). Both 1 and 2 have been structurally characterized, crystallizing in the triclinic P1̅ and monoclinic P21 space groups, respectively. These complexes contain Ti≡O units with distances of 1.624(7) and 1.644(2) Å, respectively, and represent rare examples of structurally characterized terminal titanyls within an all-oxygen coordination environment. Complexes 1 and 2 react with hydrogen peroxide to produce the corresponding peroxotitanium(IV) metaphosphate complexes [O2TiP4O12]2(4-)(3; 61% yield) and [O2TiP3O9(acac)](2-) (4; 65% yield), respectively. Both 3 and 4 have been characterized by single-crystal X-ray diffraction studies, and their solid-state structures are presented. Complex 3 functions as an oxygen atom transfer (OAT) reagent capable of oxidizing phosphorus(III) compounds (P(OMe)3, PPh3) and SMe2 at ambient temperature to result in the corresponding organic oxide with regeneration of dimer 1.

  9. Synthesis and in vitro reactivation study of isonicotinamide derivatives of 2-(hydroxyimino)-N-(pyridin-3-yl)acetamide as reactivators of Sarin and VX inhibited human acetylcholinesterase (hAChE).

    PubMed

    Karade, Hitendra N; Raviraju, G; Acharya, B N; Valiveti, Aditya Kapil; Bhalerao, Uma; Acharya, Jyotiranjan

    2016-09-15

    Previously (Karade et al., 2014), we have reported the synthesis and in vitro evaluation of bis-pyridinium derivatives of pyridine-3-yl-(2-hydroxyimino acetamide), as reactivators of sarin and VX inhibited hAChE. Few of the molecules showed superior in vivo protection efficacy (mice model) (Kumar et al., 2014; Swami et al., 2016) in comparison to 2-PAM against DFP and sarin poisoning. Encouraged by these results, herein we report the synthesis and in vitro evaluation of isonicotinamide derivatives of pyridine-3-yl-(2-hydroxyimino acetamide) (4a-4d) against sarin and VX inhibited erythrocyte ghost hAChE. Reactivation kinetics of these compounds was studied and the determined kinetic parameters were compared with that of commercial reactivators viz. 2-PAM and obidoxime. In comparison to 2-PAM and obidoxime, oxime 4a and 4b exhibited enhanced reactivation efficacy toward sarin inhibited hAChE while oxime 4c showed far greater reactivation efficacy toward VX inhibited hAChE. The acid dissociation constant and IC50 values of these oximes were determined and correlated with the observed reactivation potential.

  10. Applications of C–H Functionalization Logic to Cyclobutane Synthesis

    PubMed Central

    2015-01-01

    The application of C–H functionalization logic to target-oriented synthesis provides an exciting new venue for the development of new and useful strategies in organic chemistry. In this article, C–H functionalization reactions are explored as an alternative approach to access pseudodimeric cyclobutane natural products, such as the dictazole and the piperarborenine families. The use of these strategies in a variety of complex settings highlights the subtle geometric, steric, and electronic effects at play in the auxiliary guided C–H functionalization of cyclobutanes. PMID:24548142

  11. Scaling properties of information-theoretic quantities in density functional reactivity theory.

    PubMed

    Rong, Chunying; Lu, Tian; Ayers, Paul W; Chattaraj, Pratim K; Liu, Shubin

    2015-02-21

    Density functional reactivity theory (DFRT) employs the electron density and its related quantities to describe reactivity properties of a molecular system. Quantities from information theory such as Shannon entropy, Fisher information, and Ghosh-Berkowitz-Parr entropy are natural descriptors within the DFRT framework. They have been previously employed to quantify electrophilicity, nucleophilicity and the steric effect. In this work, we examine their scaling properties with respect to the total number of electrons. To that end, we considered their representations in terms of both the electron density and the shape function for isolated atoms and neutral molecules. We also investigated their atomic behaviors in different molecules with three distinct partitioning schemes: Bader's zero-flux, Becke's fuzzy atom, and Hirshfeld's stockholder partitioning. Strong linear relationships of these quantities as a function of the total electron population are reported for atoms, molecules, and atoms in molecules. These relationships reveal how these information-theoretic quantities depend on the molecular environment and the electron population. These trends also indicate how these quantities can be used to explore chemical reactivity for real chemical processes.

  12. Dissecting molecular descriptors into atomic contributions in density functional reactivity theory.

    PubMed

    Rong, Chunying; Lu, Tian; Liu, Shubin

    2014-01-14

    Density functional reactivity theory (DFRT) employs the electron density of a molecule and its related quantities such as gradient and Laplacian to describe its structure and reactivity properties. Proper descriptions at both molecular (global) and atomic (local) levels are equally important and illuminating. In this work, we make use of Bader's zero-flux partition scheme and consider atomic contributions for a few global reactivity descriptors in DFRT, including the density-based quantification of steric effect and related indices. Earlier, we proved that these quantities are intrinsically correlated for atomic and molecular systems [S. B. Liu, J. Chem. Phys. 126, 191107 (2007); ibid. 126, 244103 (2007)]. In this work, a new basin-based integration algorithm has been implemented, whose reliability and effectiveness have been extensively examined. We also investigated a list of simple hydrocarbon systems and different scenarios of bonding processes, including stretching, bending, and rotating. Interesting changing patterns for the atomic and molecular values of these quantities have been revealed for different systems. This work not only confirms the strong correlation between these global reactivity descriptors for molecular systems, as theoretically proven earlier by us, it also provides new and unexpected changing patterns for their atomic values, which can be employed to understand the origin and nature of chemical phenomena.

  13. Cellulose nanocrystals: synthesis, functional properties, and applications

    PubMed Central

    George, Johnsy; Sabapathi, SN

    2015-01-01

    Cellulose nanocrystals are unique nanomaterials derived from the most abundant and almost inexhaustible natural polymer, cellulose. These nanomaterials have received significant interest due to their mechanical, optical, chemical, and rheological properties. Cellulose nanocrystals primarily obtained from naturally occurring cellulose fibers are biodegradable and renewable in nature and hence they serve as a sustainable and environmentally friendly material for most applications. These nanocrystals are basically hydrophilic in nature; however, they can be surface functionalized to meet various challenging requirements, such as the development of high-performance nanocomposites, using hydrophobic polymer matrices. Considering the ever-increasing interdisciplinary research being carried out on cellulose nanocrystals, this review aims to collate the knowledge available about the sources, chemical structure, and physical and chemical isolation procedures, as well as describes the mechanical, optical, and rheological properties, of cellulose nanocrystals. Innovative applications in diverse fields such as biomedical engineering, material sciences, electronics, catalysis, etc, wherein these cellulose nanocrystals can be used, are highlighted. PMID:26604715

  14. Synthesis of substituted adamantylzinc reagents using a Mg-insertion in the presence of ZnCl₂ and further functionalizations.

    PubMed

    Sämann, Christoph; Dhayalan, Vasudevan; Schreiner, Peter R; Knochel, Paul

    2014-05-02

    The LiCl-mediated Mg-insertion in the presence of ZnCl2 allows an efficient synthesis of adamantylzinc reagents starting from the corresponding functionalized tertiary bromides. The highly reactive adamantylzinc species readily undergo a broad variety of functionalizations such as Negishi cross-couplings, Cu(I)-catalyzed acylations and allylations, and 1,4-addition reactions leading to the expected products in excellent yields. Furthermore, the adamantyl moiety could be introduced as α-substituent in terthiophene, increasing its solubility due to the higher lipophilicity and the prevention of π-stacking.

  15. Synthesis and characterization of hydrogen-bond acidic functionalized graphene

    NASA Astrophysics Data System (ADS)

    Yang, Liu; Han, Qiang; Pan, Yong; Cao, Shuya; Ding, Mingyu

    2014-05-01

    Hexafluoroisopropanol phenyl group functionalized materials have great potential in the application of gas-sensitive materials for nerve agent detection, due to the formation of strong hydrogen-bonding interactions between the group and the analytes. In this paper, take full advantage of ultra-large specific surface area and plenty of carbon-carbon double bonds and hexafluoroisopropanol phenyl functionalized graphene was synthesized through in situ diazonium reaction between -C=C- and p-hexafluoroisopropanol aniline. The identity of the as-synthesis material was confirmed by transmission electron microscopy, Raman spectroscopy, ultraviolet visible spectroscopy, X-ray photoelectron spectroscopy and thermo gravimetric analysis. The synthesis method is simply which retained the excellent physical properties of original graphene. In addition, the novel material can be assigned as an potential candidate for gas sensitive materials towards organophosphorus nerve agent detection.

  16. Integrin alpha1beta1 controls reactive oxygen species synthesis by negatively regulating epidermal growth factor receptor-mediated Rac activation.

    PubMed

    Chen, Xiwu; Abair, Tristin D; Ibanez, Maria R; Su, Yan; Frey, Mark R; Dise, Rebecca S; Polk, D Brent; Singh, Amar B; Harris, Raymond C; Zent, Roy; Pozzi, Ambra

    2007-05-01

    Integrins control many cell functions, including generation of reactive oxygen species (ROS) and regulation of collagen synthesis. Mesangial cells, found in the glomerulus of the kidney, are able to produce large amounts of ROS via the NADPH oxidase. We previously demonstrated that integrin alpha1-null mice develop worse fibrosis than wild-type mice following glomerular injury and this is due, in part, to excessive ROS production by alpha1-null mesangial cells. In the present studies, we describe the mechanism whereby integrin alpha1-null mesangial cells produce excessive ROS. Integrin alpha1-null mesangial cells have constitutively increased basal levels of activated Rac1, which result in its increased translocation to the cell membrane, excessive ROS production, and consequent collagen IV deposition. Basal Rac1 activation is a direct consequence of ligand-independent increased epidermal growth factor receptor (EGFR) phosphorylation in alpha1-null mesangial cells. Thus, our study demonstrates that integrin alpha1beta1-EGFR cross talk is a key step in negatively regulating Rac1 activation, ROS production, and excessive collagen synthesis, which is a hallmark of diseases characterized by irreversible fibrosis.

  17. Self-organised synthesis of Rh nanostructures with tunable chemical reactivity

    PubMed Central

    2007-01-01

    Nonequilibrium periodic nanostructures such as nanoscale ripples, mounds and rhomboidal pyramids formed on Rh(110) are particularly interesting as candidate model systems with enhanced catalytic reactivity, since they are endowed with steep facets running along nonequilibrium low-symmetry directions, exposing a high density of undercoordinated atoms. In this review we report on the formation of these novel nanostructured surfaces, a kinetic process which can be controlled by changing parameters such as temperature, sputtering ion flux and energy. The role of surface morphology with respect to chemical reactivity is investigated by analysing the carbon monoxide dissociation probability on the different nanostructured surfaces.

  18. Chemical synthesis and functionalization of clickable glycosylphosphatidylinositol anchors.

    PubMed

    Swarts, Benjamin M; Guo, Zhongwu

    2011-01-01

    Glycosylphosphatidylinositol (GPI) anchorage is a common posttranslational modification of eukaryotic proteins. Chemical synthesis of structurally defined GPIs and GPI derivatives is a necessary step toward understanding the properties and functions of these molecules in biological systems. In this work, the synthesis of several functionalized GPI anchors was accomplished using the para-methoxybenzyl (PMB) group for permanent hydroxyl protection, which allowed the incorporation of functionalities that are incompatible with permanent protecting groups traditionally used in carbohydrate synthesis. A flexible convergent-divergent assembly strategy enabled efficient access to a diverse set of target structures, including "clickable" Alkynyl-GPIs 1 and 2 and Azido-GPI 3. For global deprotection, a one-pot reaction was employed to afford the target GPIs in excellent yields (85-97%). Fully deprotected clickable GPIs 2 and 3 were readily conjugated to imaging and affinity probes via Cu(I)-catalyzed and Cu-free strain-promoted [3+2] cycloaddition, respectively, resulting in GPI-Fluor 4 and GPI-Biotin 5.

  19. Infant adrenocortical reactivity and behavioral functioning: Relation to early exposure to maternal intimate partner violence

    PubMed Central

    Levendosky, Alytia A.; Bogat, G. Anne; Lonstein, Joseph S.; Martinez-Torteya, Cecilia; Muzik, Maria; Granger, Douglas A.; von Eye, Alexander

    2016-01-01

    Prenatal stress negatively affects fetal development, which in turn may affect infant hypothalamic-pituitary adrenal (HPA) axis regulation and behavioral functioning. We examined effects of exposure to a traumatic stressor in families [intimate partner violence (IPV)] on both infants’ HPA axis reactivity to stress and their internalizing and externalizing behaviors. Infants (n= 182, 50% girls, x̄ age = 11.77 months) were exposed to a laboratory challenge task designed to induce frustration and anger (i.e., arm restraint). Saliva samples were taken pre-task and 20 and 40 minutes post-task and then assayed for cortisol. Mothers reported on their pregnancy and postpartum IPV history, current mental health, substance use, and their infants’ behaviors. Structural equation modeling revealed that prenatal, but not postnatal, IPV was independently associated with infant cortisol reactivity and problem behavior. Maternal mental health predicted infant behavioral functioning but not infant HPA axis reactivity. These findings are consistent with the prenatal programming hypothesis; that is, early life stress affects later risk and vulnerability for altered physiological and behavioral regulation. PMID:26482431

  20. Differences in latent inhibition as a function of the autogenous-reactive OCD subtype.

    PubMed

    Lee, Han-Joo; Telch, Michael J

    2010-07-01

    We examined differences in a visual search-based latent inhibition (LI) task in 48 non-treatment seeking individuals diagnosed with obsessive-compulsive disorder (OCD) and 26 non-OCD controls, using a visual search-based LI task as a function of participants' primary obsessional presentation based on the autogenous-reactive subtype model of obsessions (Lee & Kwon, 2003; Lee & Telch, 2007). We hypothesized that LI would be significantly attenuated among OCD participants whose primary obsessions were characterized by aversive impulses, images, or thoughts with sexual, aggressive, blasphemous, and repulsive themes (autogenous obsessions) due to their weakened attentional inhibitory mechanisms and elevated schizotypal personality features, as compared with those whose primary obsessions were characterized by somewhat realistic aversive mental intrusions about contamination, mistakes, accidents, or disarray (reactive obsession) and non-OCD controls. Results showed that those primarily displaying autogenous obsessions failed to display LI, whereas those primarily displaying reactive obsessions and non-OCD controls displayed significant LI effects. Our data suggest that the magnitude of LI varies as a function of primary obsessional presentations among individuals with OCD.

  1. Synthesis of Nano-ZrO2 by Reactive Plasma processing

    NASA Astrophysics Data System (ADS)

    Jayakumar, S.; Thiyagarajan, T. K.; Ananthapadmanabhan, P. V.; Sreekumar, K. P.; Perumal, K.; Mishra, S. C.; Su, L. T.; Tok, A. I. Y.

    2011-07-01

    A novel technique, reactive plasma processing was utilized to produce nano-crystalline Zirconia from zirconium hydride. XRD result showed mixture of monoclinic and tetragonal phases. TEM analysis reveals 95% of the particles were in the range 18-23 nm.

  2. Synthesis of oxidized guar gum by dry method and its application in reactive dye printing.

    PubMed

    Gong, Honghong; Liu, Mingzhu; Zhang, Bing; Cui, Dapeng; Gao, Chunmei; Ni, Boli; Chen, Jiucun

    2011-12-01

    The aim of this study was to prepare oxidized guar gum with a simple dry method, basing on guar gum, hydrogen peroxide and a small amount of solvent. To obtain a product with suitable viscosity for reactive dye printing, the effects of various factors such as the amount of oxidant and solvent, reaction temperature and time were studied with respect to the viscosity of reaction products. The product was characterized by Fourier transform infrared spectroscopy, size exclusion chromatography, scanning electron microscopy and differential scanning calorimetry. The hydrated rate of guar gum and oxidized guar gum was estimated through measuring the required time when their solutions (1%, w/v) reached the maximum viscosity. The effects of the salt concentration and pH on viscosity of the resultant product were studied. The mixed paste containing oxidized guar gum and carboxymethyl starch was prepared and its viscosity was determined by the viscometer. The rheological property of the mixed paste was appraised by the printing viscosity index. In addition, the applied effect of mixed paste in reactive dye printing was examined by assessing the fabric stiffness, color yield and sharp edge to the printed image in comparison with sodium alginate. And the results indicated that the mixed paste could partially replace sodium alginate as thickener in reactive dye printing. The study also showed that the method was low cost and eco-friendly and the product would have an extensive application in reactive dye printing.

  3. Synthesis and application of polyepoxide cardanol glycidyl ether as biobased polyepoxide reactive diluent for epoxy resin

    USDA-ARS?s Scientific Manuscript database

    Polyepoxide cardanol glycidyl ether (PECGE), a novel cardanol derivative, was synthesized and used as reactive diluent for petroleum-based epoxy resin in this work. The synthetic condition was first optimized, and the resultant PECGE diluent was characterized using Fourier transform infrared spectro...

  4. Decreased NK cell functions in obesity can be reactivated by fat mass reduction.

    PubMed

    Jahn, Janine; Spielau, Marco; Brandsch, Corinna; Stangl, Gabriele I; Delank, Karl-Stefan; Bähr, Ina; Berreis, Tobias; Wrann, Christiane D; Kielstein, Heike

    2015-11-01

    Natural killer (NK) cells are the first defense against malignant cells, and their functions are severely impaired in individuals with obesity. However, it is not known whether functions can be re-activated after weight loss. The alterations of NK cell functions after fat mass reduction were investigated. Thirty-two healthy adults with obesity were divided into control and experimental groups. Participants of the experimental group performed a 3-month program of exercise training and nutrition. Anthropometric, physiological, and metabolic parameters and plasma adipocytokines were determined. Peripheral blood mononuclear cells were analyzed by means of flow cytometry and Western blot assay for various NK cell-specific functional parameters and leptin signaling components. NK cell-mediated cytotoxicity assay with leptin stimulation was performed. Male participants significantly decreased their body fat mass (P < 0.05) and increased physical fitness (P < 0.05). Plasma leptin levels were significantly reduced (P < 0.05) and intracellular interferon gamma (IFN-γ) expression in CD56(dim) NK cells was significantly increased (P < 0.001) 3 months after study end. Stimulation of NK-92 cells with different leptin dosages revealed a significant dose-dependent decrease of specific tumor cell lysis. The present study demonstrates a reactivation of NK cell functionality after body fat mass reduction in persons with obesity. © 2015 The Obesity Society.

  5. Structure, vibrational analysis, electronic properties and chemical reactivity of two benzoxazole derivatives: Functional density theory study

    NASA Astrophysics Data System (ADS)

    Zaater, Sihem; Bouchoucha, Afaf; Djebbar, Safia; Brahimi, Meziane

    2016-11-01

    In the present work we calculate structural parameters, vibrational spectra (IR, 1H NMR and UV-Visible Absorption) and corresponding mode of vibrational assignments of two ligands derived from benzoxazole; L1: 2-(5-(trifluoromethylpyridin-2-yl)-benzoxazole and L2: 2-(5-methylpyridin-2-yl)-benzoxazole at B3LYP/6-311++G** level, in the gas phase. The HOMO and LUMO study is used to determine the charge transfer within the molecules. Reactivity descriptors such as ionization energy, electronic affinity, global hardness, global softness, electrophilicity, nucleophilicity and condensed Fukui functions using NBO population analysis are also determined to predict the reactivity of L1 and L2. The calculated geometrical parameters are in good agreement with those of similar benzoxazole derivatives. Theoretical frequencies assignments confirmed the experimental ones of these benzoxazole derivatives.

  6. The Nitrilimine-Alkene Cycloaddition Regioselectivity Rationalized by Density Functional Theory Reactivity Indices.

    PubMed

    Molteni, Giorgio; Ponti, Alessandro

    2017-01-26

    Conventional frontier molecular orbital theory is not able to satisfactorily explain the regioselectivity outcome of the nitrilimine-alkene cycloaddition. We considered that conceptual density functional theory (DFT) could be an effective theoretical framework to rationalize the regioselectivity of the title reaction. Several nitrilimine-alkene cycloadditions were analyzed, for which we could find regioselectivity data in the literature. We computed DFT reactivity indices at the B3LYP/6-311G(2d,p)//B3LYP/6-31G(d,p) and employed the grand potential stabilization criterion to calculate the preferred regioisomer. Experimental and calculated regioselectivity agree in the vast majority of cases. It was concluded that predominance of a single regioisomer can be obtained by maximizing (i) the chemical potential difference between nitrilimine and alkene and (ii) the local softness difference between the reactive atomic sites within each reactant. Such maximization can be achieved by carefully selecting the substituents on both reactants.

  7. Rejection Reactivity, Executive Function Skills, and Social Adjustment Problems of Inattentive and Hyperactive Kindergarteners

    PubMed Central

    Motamedi, Mojdeh; Bierman, Karen; Huang-Pollock, Cynthia L.

    2015-01-01

    This study examined emotional reactivity to rejection and executive function (EF) skills as potential mediators of the social behavior problems of inattentive and hyperactive kindergarteners. Participants included 171 children, including 107 with clinical levels of ADHD symptoms, 23 with sub-clinical levels of ADHD symptoms, and 41 typically-developing children (63% male; 73% Caucasian, 11% African American, 4% Latino/Hispanic, 1% Asian, and 11% multiracial; Mage = 5.2 years). Inattention (but not hyperactivity) was uniquely associated with poor EF, social withdrawal, and aggression. In structural equation models, EF skills mediated the associations between inattention and both aggression and social withdrawal. Hyperactivity (but not inattention) was uniquely associated with rejection reactivity and each contributed uniquely to aggression. Findings suggest that difficulties with emotion regulation may warrant more attention in early interventions planned for children with high levels of ADHD symptoms. PMID:27158194

  8. Power and power-to-flow reactivity transfer functions in EBR-II (Experimental Breeder Reactor II) fuel

    SciTech Connect

    Grimm, K.N.; Meneghetti, D. )

    1989-11-01

    Reactivity transfer functions are important in determining the reactivity history during a power transient. Overall nodal transfer functions have been calculated for different subassembly types in the Experimental Breeder Reactor II (EBR-II). Steady-state calculations for temperature changes and, hence, reactivities for power changes have been separated into power and power-to-flow-dependent terms. Axial nodal transfer functions separated into power and power-to-flow-dependent components are reported in this paper for a typical EBR-II fuel pin. This provides an improved understanding of the time dependence of these components in transient situations.

  9. Magnetic Iron Oxide Nanoparticles: Synthesis and Surface Functionalization Strategies

    PubMed Central

    2008-01-01

    Surface functionalized magnetic iron oxide nanoparticles (NPs) are a kind of novel functional materials, which have been widely used in the biotechnology and catalysis. This review focuses on the recent development and various strategies in preparation, structure, and magnetic properties of naked and surface functionalized iron oxide NPs and their corresponding application briefly. In order to implement the practical application, the particles must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of iron oxide NPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The problems and major challenges, along with the directions for the synthesis and surface functionalization of iron oxide NPs, are considered. Finally, some future trends and prospective in these research areas are also discussed. PMID:21749733

  10. Purines regulate adult brain subventricular zone cell functions: contribution of reactive astrocytes.

    PubMed

    Boccazzi, Marta; Rolando, Chiara; Abbracchio, Maria P; Buffo, Annalisa; Ceruti, Stefania

    2014-03-01

    Brain injuries modulate activation of neural stem cells (NSCs) in the adult brain. In pathological conditions, the concentrations of extracellular nucleotides (eNTs) raise several folds, contribute to reactive gliosis, and possibly directly affect subventricular zone (SVZ) cell functioning. Among eNTs and derived metabolites, the P2Y1 receptor agonist ADP strongly promotes astrogliosis and might also influence SVZ progenitor activity. Here, we tested the ability of the stable P2Y1 agonist adenosine 5'-O-(2-thiodiphosphate) (ADPβS) to control adult NSC functions both in vitro and in vivo, with a focus on the possible effects exerted by reactive astrocytes. In the absence of growth factors, ADPβS promoted proliferation and differentiation of SVZ progenitors. Moreover, ADPβS-activated astrocytes markedly changed the pattern of released cytokines and chemokines, and strongly modulated neurosphere-forming capacity of SVZ progenitors. Notably, a significant enhancement in proliferation was observed when SVZ cells, initially grown in the supernatant of astrocytes exposed to ADPβS, were shifted to normal medium. In vivo, ADPβS administration in the lateral ventricle of adult mice by osmotic minipumps caused diffused reactive astrogliosis, and a strong response of SVZ progenitors. Indeed, proliferation of glial fibrillary acidic protein-positive NSCs increased and led to a significant expansion of SVZ transit-amplifying progenitors and neuroblasts. Lineage tracing experiments performed in the GLAST::CreERT2;Rosa-YFP transgenic mice further demonstrated that ADPβS promoted proliferation of glutamate/aspartate transporter-positive progenitors and sustained their progression toward the generation of rapidly dividing progenitors. Altogether, our results show that the purinergic system crucially affects SVZ progenitor activities both directly and through the involvement of reactive astrocytes.

  11. Functions of the Epstein-Barr virus EBNA1 protein in viral reactivation and lytic infection.

    PubMed

    Sivachandran, Nirojini; Wang, Xueqi; Frappier, Lori

    2012-06-01

    EBNA1 is the only nuclear Epstein-Barr virus (EBV) protein expressed in both latent and lytic modes of infection. While EBNA1 is known to play several important roles in latent infection, the reason for its continued expression in lytic infection is unknown. Here we identified two roles for EBNA1 in the reactivation of latent EBV to the lytic cycle in epithelial cells. First, EBNA1 depletion in latently infected cells was shown to positively contribute to spontaneous EBV reactivation, showing that EBNA1 has a role in suppressing reactivation. Second, when the lytic cycle was induced, EBNA1 depletion decreased lytic gene expression and DNA amplification, showing that it positively contributed to lytic infection. Since we have previously shown that EBNA1 disrupts promyelocytic leukemia (PML) nuclear bodies, we investigated whether this function could account for the effects of EBNA1 on lytic infection by repeating the experiments with cells lacking PML proteins. In the absence of PML, EBNA1 did not promote lytic infection, indicating that the EBNA1-mediated PML disruption is responsible for promoting lytic infection. In keeping with this conclusion, PML silencing was found to be sufficient to induce the EBV lytic cycle. Finally, by generating cells with single PML isoforms, we showed that individual PML isoforms were sufficient to suppress EBV lytic reactivation, although PML isoform IV (PML IV) was ineffective because it was most efficiently degraded by EBNA1. Our results provide the first function for EBNA1 in lytic infection and show that EBNA1 interactions with PML IV lead to a loss of PML nuclear bodies (NBs) that promotes lytic infection.

  12. Functions of the Epstein-Barr Virus EBNA1 Protein in Viral Reactivation and Lytic Infection

    PubMed Central

    Sivachandran, Nirojini; Wang, Xueqi

    2012-01-01

    EBNA1 is the only nuclear Epstein-Barr virus (EBV) protein expressed in both latent and lytic modes of infection. While EBNA1 is known to play several important roles in latent infection, the reason for its continued expression in lytic infection is unknown. Here we identified two roles for EBNA1 in the reactivation of latent EBV to the lytic cycle in epithelial cells. First, EBNA1 depletion in latently infected cells was shown to positively contribute to spontaneous EBV reactivation, showing that EBNA1 has a role in suppressing reactivation. Second, when the lytic cycle was induced, EBNA1 depletion decreased lytic gene expression and DNA amplification, showing that it positively contributed to lytic infection. Since we have previously shown that EBNA1 disrupts promyelocytic leukemia (PML) nuclear bodies, we investigated whether this function could account for the effects of EBNA1 on lytic infection by repeating the experiments with cells lacking PML proteins. In the absence of PML, EBNA1 did not promote lytic infection, indicating that the EBNA1-mediated PML disruption is responsible for promoting lytic infection. In keeping with this conclusion, PML silencing was found to be sufficient to induce the EBV lytic cycle. Finally, by generating cells with single PML isoforms, we showed that individual PML isoforms were sufficient to suppress EBV lytic reactivation, although PML isoform IV (PML IV) was ineffective because it was most efficiently degraded by EBNA1. Our results provide the first function for EBNA1 in lytic infection and show that EBNA1 interactions with PML IV lead to a loss of PML nuclear bodies (NBs) that promotes lytic infection. PMID:22491455

  13. New strategy for synthesis and functionalization of carbon nanoparticles.

    PubMed

    Jiang, Hongquan; Chen, Feng; Lagally, Max G; Denes, Ferencz S

    2010-02-02

    We describe a novel "one-step" combined synthesis and functionalization of carbon nanoparticles, using a new generation of all-in-one small submerged-arc plasma reactor that we have developed. We take advantage of long-lived free radicals generated by a submerged-arc helium atmosphere plasma and resident on the nanoparticle surfaces to supply ethylenediamine directly after the plasma to functionalize the carbon nanoparticles. XPS, TG/DTG, FTIR, and fluorescence tests confirm the viability of this new amination process. The nanoparticles are small and relatively uniformly sized. Their dispersibility in aqueous solution is significant.

  14. Facile synthesis of fluorescent polymer nanoparticles by covalent modification-nanoprecipitation of amine-reactive ester polymers.

    PubMed

    Lee, Yeonju; Hanif, Sadaf; Theato, Patrick; Zentel, Rudolf; Lim, Jeewoo; Char, Kookheon

    2015-06-01

    Emission wavelength control in fluorescent nanoparticles (NPs) is crucial for their applications. In the case of inorganic quantum dots or dye-impregnated silica NPs, such a control is readily achieved by changing the size of the particles or choosing appropriate fluorescent dyes, respectively. A similar modular approach for controlling the emission wavelength of fluo-rescent polymer NPs, however, is difficult. This article reports on fluorescent polymer NPs, the synthesis of which provides a platform for a modular approach towards the preparation of fluorescent NPs of desired emission wavelength. Atom-transfer radical polymerization (ATRP) is employed to synthesize reactive ester polymers, which are then easily modified with a commercially available dye and subsequently subjected to nanoprecipitation. The resulting NPs, with low size polydispersity, show an enhanced emission quantum yield when compared with the same dye molecules in solution.

  15. Anesthetic preconditioning improves adenosine triphosphate synthesis and reduces reactive oxygen species formation in mitochondria after ischemia by a redox dependent mechanism.

    PubMed

    Novalija, Enis; Kevin, Leo G; Eells, Janis T; Henry, Michele M; Stowe, David F

    2003-05-01

    Mitochondrial changes that characterize the heart after anesthetic preconditioning (APC) or the mechanisms by which mitochondrial triggering factors lead to protection are unknown. This study hypothesized that generation of reactive oxygen species (ROS) during APC is required to initiate the mitochondrial protective effects, and that APC leads to improved mitochondrial electron transport chain function and cardiac function during reperfusion. Isolated guinea pig hearts were subject to 30 min ischemia and 120 min reperfusion. Prior to ischemia hearts were either untreated (I/R), or treated with sevoflurane (APC), in the presence or absence of the ROS scavenger tiron (TIR), or the superoxide dismutase mimetic MnTBAP (TBAP). Intracellular ROS were measured by spectrofluorometry using the fluorescent probe dihydroethidium (DHE). In another series of experiments, using the same protocol, hearts were reperfused for only 5 min and removed for measurement of adenosine triphosphate (ATP) synthesis by luciferin-luciferase luminometry and ROS generation by dichlorohydro-fluorescein (DCF) fluorescence in isolated mitochondria. The APC improved cardiac function and reduced infarction. Tiron or MnTBAP abrogated the protection afforded by APC. Mitochondrial ATP synthesis was decreased by 70 +/- 3% after IR alone, by only 7 +/- 3% after APC, by 69 +/- 2% after APC+TIR, and by 71 +/- 3% after APC + TBAP. Mitochondrial ROS formation (DCF) increased by 48 +/- 3% after IR alone, by 0 +/- 2% after APC, by 43 +/- 4% after APC + TIR, and by 46 +/- 3% after APC + TBAP. ROS generation (DHE) was increased in I/R group at 5 and 120 min reperfusion. This was attenuated by APC but this protective effect was abrogated in APC + TIR and APC + TBAP groups. The results indicate that ROS are central both in triggering and mediating APC, and that the mitochondrion is the target for these changes.

  16. Functional Characterization of Regulatory Macrophages That Inhibit Graft-reactive Immunity.

    PubMed

    Ochando, Jordi; Conde, Patricia

    2017-06-07

    Macrophage accumulation in transplanted organs has long been recognized as a feature of allograft rejection(1). Immunogenic monocytes infiltrate the allograft early after transplantation, mount a graft reactive response against the transplanted organ, and initiate organ rejection(2). Recent data suggest that suppressive macrophages facilitate successful long-term transplantation(3) and are required for the induction of transplantation tolerance(4). This suggests a multidimensional concept of macrophage ontogeny, activation, and function, which demands a new roadmap for the isolation and analysis of macrophage function(5). Due to the plasticity of macrophages, it is necessary to provide a methodology to isolate and characterize macrophages, depending on the tissue environment, and to define their functions according to different scenarios. Here, we describe a protocol for immune characterization of graft-infiltrating macrophages and the methods we used to functionally evaluate their capacity to inhibit CD8(+) T proliferation and to promote CD4(+)Foxp3(+) Treg expansion in vitro.

  17. Rapid Microwave Synthesis of Perovskite Oxide Nanostructures with Enhanced Functionality

    NASA Astrophysics Data System (ADS)

    Salazar, Gregory; Datta, Anuja; Mukherjee, Pritish

    2015-03-01

    Perovskite oxides are an important class of materials having high dielectric and piezoelectric coefficients, switchable ferroelectric (FE) polarization and interesting optical and electrical properties. Realization of functional devices based on classic perovskite oxides such as Pb(Zr0.52Ti0.48) O3 (PZT), and emerging Pb-free noncentrosymmetric (NCS) oxides, such as, ZnSnO3, ZnTiO3 and CaTiO3 have reinforced the investigation of these materials in multiple dimensions and length scales. However, large-scale synthesis and integration of ordered low-dimensional structures is a challenge, due to their complicated methodologies, high-cost and difficulties with phase stability. We discuss a generalized, cost-effective, rapid microwave synthesis route for size and shape selective nanostructure growth of these functional perovskite oxides on industrially viable flexible and hard substrates, stabilized by an enhanced ionic covalence. The rational synthesis approach allowed improved tunability of the size, shape, and orientation of the structures with improved electrical and FE properties. The facile fabrication route of these nanostructures may expand the outreach of probes for understanding the structure-property relationships in these hitherto unexplored and technologically important materials.

  18. Design, synthesis, and evaluation of carnosine derivatives as selective and efficient sequestering agents of cytotoxic reactive carbonyl species.

    PubMed

    Vistoli, Giulio; Orioli, Marica; Pedretti, Alessandro; Regazzoni, Luca; Canevotti, Renato; Negrisoli, Gianpaolo; Carini, Marina; Aldini, Giancarlo

    2009-06-01

    Carnosine aryl derivatives as sequestering agents of RCS: Reactive carbonyl species (RCS) are cytotoxic mediators representing a novel drug target, as they are presumed to play a pathogenic role in several diseases. Carnosine is a selective RCS-sequestering agent, but is rapidly hydrolyzed by serum carnosinase. Herein we describe the in silico design, synthesis, and evaluation of a set of carnosine aryl derivatives.Reactive carbonyl species (RCS) are important cytotoxic mediators generated by lipid oxidation of polyunsaturated fatty acids (PUFAs) and represent a novel drug target, as they are presumed to play a pathogenic role in several diseases. L-Carnosine (L-CAR, beta-alanyl-L-histidine) is a specific detoxifying agent of RCS, but is rapidly hydrolyzed in human serum by carnosinase, a specific dipeptidase. Herein we describe the in silico design, synthesis, and biological evaluation of carnosine derivatives that are resistant to carnosinase and that have increased quenching efficacy. Stability against carnosinase-mediated turnover was achieved by isomerization of the histidine residue, leading to D-carnosine (D-CAR, beta-alanyl-D-histidine), which maintains the same quenching activity of L-carnosine. A molecular modeling approach was then used to design derivatives characterized by an increased quenching efficacy. The most promising candidates were synthesized, and their stability and quenching activity were evaluated. This study describes a set of aryl derivatives that are characterized by high stability in human plasma and a quenching activity toward 4-hydroxy-trans-2-nonenal (HNE), chosen as a model of RCS, up to threefold greater than D-carnosine.

  19. Locally Estimated Hemodynamic Response Function and Activation Detection Sensitivity in Heroin-Cue Reactivity Study

    PubMed Central

    Maleki-Balajoo, Somayeh; Hossein-Zadeh, Gholam-Ali; Soltanian-Zadeh, Hamid; Ekhtiari, Hamed

    2016-01-01

    Introduction: A fixed hemodynamic response function (HRF) is commonly used for functional magnetic resonance imaging (fMRI) analysis. However, HRF may vary from region to region and subject to subject. We investigated the effect of locally estimated HRF (in functionally homogenous parcels) on activation detection sensitivity in a heroin cue reactivity study. Methods: We proposed a novel exploratory method for brain parcellation based on a probabilistic model to segregate the brain into spatially connected and functionally homogeneous components. Then, we estimated HRF and detected activated regions in response to an experimental task in each parcel using a joint detection estimation (JDE) method. We compared the proposed JDE method with the general linear model (GLM) that uses a fixed HRF and is implemented in FEAT (as a part of FMRIB Software Library, version 4.1). Results: 1) Regions detected by JDE are larger than those detected by fixed HRF, 2) In group analysis, JDE found areas of activation not detected by fixed HRF. It detected drug craving a priori “regions-of-interest” in the limbic lobe (anterior cingulate cortex [ACC], posterior cingulate cortex [PCC] and cingulate gyrus), basal ganglia, especially striatum (putamen and head of caudate), and cerebellum in addition to the areas detected by the fixed HRF method, 3) JDE obtained higher Z-values of local maxima compared to those obtained by fixed HRF. Conclusion: In our study of heroin cue reactivity, our proposed method (that estimates HRF locally) outperformed the conventional GLM that uses a fixed HRF. PMID:27872691

  20. Polybromocyclopentadienes in the diene synthesis reaction. VI. The reactivity of hexabromo- and 5,5-dimethoxytetrabromo-1,3-cyclopentadienes in the diene synthesis reaction with bismaleimides

    SciTech Connect

    Mustafaev, A.M.; Guseinov, M.M.; Gasanova, K.M.; Gadzhieva, S.T.

    1987-10-10

    The adducts from the diene condensation of hexabromo- and 5,5-dimethoxytetrabromo-1,3-cyclopentadienes with bismaleimides were obtained and characterized. The reactivity of hexabromo- and 5,5-dimethoxytetrabromo-1,3-cyclopentadienes in the diene synthesis reactions with bismaleimides and with the monoadducts 1,4,5,6,7,7-hexabromo- and 1,4,5,6-tetrabromo-7,7-dimethoxybicyclo-(2.2.1)-hept-5-ene-2,3-dicarboximides was studied. In these reactions hexabromo-1,3-cyclopentadiene acts as diene-acceptor, while 5,5-dimethoxytetrabromo-1,3-cyclopentadiene acts as diene-donor. It is suggested that the reactivity of the addends in the investigated reaction series depends not only on their donor-acceptor characteristics but also on the localization energy. The IR spectra of the adducts were recorded in Vaseline oil on a UR-20 spectrophotometer. The PMR spectra were measured on a Tesla BS-487B instrument at 80 MHz with DMFA-d/sub 7/ as solvent and TMS as internal standard.

  1. Alphavirus RNA synthesis and non-structural protein functions.

    PubMed

    Rupp, Jonathan C; Sokoloski, Kevin J; Gebhart, Natasha N; Hardy, Richard W

    2015-09-01

    The members of the genus Alphavirus are positive-sense RNA viruses, which are predominantly transmitted to vertebrates by a mosquito vector. Alphavirus disease in humans can be severely debilitating, and depending on the particular viral species, infection may result in encephalitis and possibly death. In recent years, alphaviruses have received significant attention from public health authorities as a consequence of the dramatic emergence of chikungunya virus in the Indian Ocean islands and the Caribbean. Currently, no safe, approved or effective vaccine or antiviral intervention exists for human alphavirus infection. The molecular biology of alphavirus RNA synthesis has been well studied in a few species of the genus and represents a general target for antiviral drug development. This review describes what is currently understood about the regulation of alphavirus RNA synthesis, the roles of the viral non-structural proteins in this process and the functions of cis-acting RNA elements in replication, and points to open questions within the field.

  2. Synthesis, characterization, and in vitro biological evaluation of highly stable diversely functionalized superparamagnetic iron oxide nanoparticles

    NASA Astrophysics Data System (ADS)

    Bhattacharya, Dipsikha; Sahu, Sumanta K.; Banerjee, Indranil; Das, Manasmita; Mishra, Debashish; Maiti, Tapas K.; Pramanik, Panchanan

    2011-09-01

    In this article, we report the design and synthesis of a series of well-dispersed superparamagnetic iron oxide nanoparticles (SPIONs) using chitosan as a surface modifying agent to develop a potential T 2 contrast probe for magnetic resonance imaging (MRI). The amine, carboxyl, hydroxyl, and thiol functionalities were introduced on chitosan-coated magnetic probe via simple reactions with small reactive organic molecules to afford a series of biofunctionalized nanoparticles. Physico-chemical characterizations of these functionalized nanoparticles were performed by TEM, XRD, DLS, FTIR, and VSM. The colloidal stability of these functionalized iron oxide nanoparticles was investigated in presence of phosphate buffer saline, high salt concentrations and different cell media for 1 week. MRI analysis of human cervical carcinoma (HeLa) cell lines treated with nanoparticles elucidated that the amine-functionalized nanoparticles exhibited higher amount of signal darkening and lower T 2 relaxation in comparison to the others. The cellular internalization efficacy of these functionalized SPIONs was also investigated with HeLa cancer cell line by magnetically activated cell sorting (MACS) and fluorescence microscopy and results established selectively higher internalization efficacy of amine-functionalized nanoparticles to cancer cells. These positive attributes demonstrated that these nanoconjugates can be used as a promising platform for further in vitro and in vivo biological evaluations.

  3. Synthesis and electrochemical preformances of tribasic and tetrabasic lead sulfates prepared by reactive grinding

    NASA Astrophysics Data System (ADS)

    Grugeon-Dewaele, S.; Laruelle, S.; Joliveau-Vallat, F.; Torcheux, L.; Delahaye-Vidal, A.

    Tribasic lead sulfate (3BS) and tetrabasic lead sulfate (4BS), used as precursors of the positive active material in the lead/acid batteries, were prepared by a new method: reactive grinding. The effects of various experimental parameters (stoichiometry, hygrometry of the starting compounds, duration of mechanical treatment) upon the nature and morphological features of the resulting phase were investigated. Among them, hygrometry turned out to be the most critical one. With water in excess, only 3BS was produced while dry reagents led to 4BS. In both cases, samples with a small particle size and high reactivity were obtained. In order to evaluate the influence of the morphology upon the electrochemical performances of such grinding produced samples, the capacity was measured and compared with that of traditional 3BS and 4BS samples.

  4. Reactive Coevaporation Synthesis and Characterization of SrTiO3 Thin Films

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hiromu; Matsubara, Shogo; Miyasaka, Yoichi

    1991-09-01

    SrTiO3 thin films were prepared by the reactive coevaporation method, where the Ti and Sr metals were evaporated in oxygen ambient with an E-gun and K-cell, respectively. A uniform depth profile in composition was achieved by altering the Ti evaporation rate according to the Sr evaporation rate change. A typical dielectric constant of 170 was measured on films of 75 nm in thickness. The in-situ annealing in oxygen plasma reduced the leakage current.

  5. Trivalent boron nucleophile as a new tool in organic synthesis: reactivity and asymmetric induction.

    PubMed

    Cid, Jessica; Gulyás, Henrik; Carbó, Jorge J; Fernández, Elena

    2012-05-07

    Boron compounds have been traditionally regarded as "Lewis acids" preferring to accept electrons rather than donate them in the course of their reactions but current examples of unusual reactivity between tricoordinated boranes and electrophilic sites suggest a new conceptual context for the boryl moieties, based on their nucleophilic character which can be enhanced depending on the substituents on boron. This journal is © The Royal Society of Chemistry 2012

  6. Oxygen precursor to the reactive intermediate in methanol synthesis by Cu-ZSM-5.

    PubMed

    Smeets, Pieter J; Hadt, Ryan G; Woertink, Julia S; Vanelderen, Pieter; Schoonheydt, Robert A; Sels, Bert F; Solomon, Edward I

    2010-10-27

    The reactive oxidizing species in the selective oxidation of methane to methanol in oxygen activated Cu-ZSM-5 was recently defined to be a bent mono(μ-oxo)dicopper(II) species, [Cu(2)O](2+). In this communication we report the formation of an O(2)-precursor of this reactive site with an associated absorption band at 29,000 cm(-1). Laser excitation into this absorption feature yields a resonance Raman (rR) spectrum characterized by (18)O(2) isotope sensitive and insensitive vibrations, νO-O and νCu-Cu, at 736 (Δ(18)O(2) = 41 cm(-1)) and 269 cm(-1), respectively. These define the precursor to be a μ-(η(2):η(2)) peroxo dicopper(II) species, [Cu(2)(O(2))](2+). rR experiments in combination with UV-vis absorption data show that this [Cu(2)(O(2))](2+) species transforms directly into the [Cu(2)O](2+) reactive site. Spectator Cu(+) sites in the zeolite ion-exchange sites provide the two electrons required to break the peroxo bond in the precursor. O(2)-TPD experiments with (18)O(2) show the incorporation of the second (18)O atom into the zeolite lattice in the transformation of [Cu(2)(O(2))](2+) into [Cu(2)O](2+). This study defines the mechanism of oxo-active site formation in Cu-ZSM-5.

  7. Synthesis and characterization of carboxymethyl potato starch and its application in reactive dye printing.

    PubMed

    Zhang, Bing; Gong, Honghong; Lü, Shaoyu; Ni, Boli; Liu, Mingzhu; Gao, Chunmei; Huang, Yinjuan; Han, Fei

    2012-11-01

    Carboxymethyl potato starch (CMPS) was synthesized with a simple dry and multi-step method as a product of the reaction of native potato starch and monochloroacetic acid in the presence of sodium hydroxide. The influence of the molar ratio of sodium hydroxide to anhydroglucose unit, the volume of 95% (v/v) ethanol, the rotation rate of motor driven stirrer and the reaction time for degree of substitution (DS) were evaluated. The product was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray diffractometry (XRD). FTIR spectrometry showed new bonds at 1618 and 1424 cm⁻¹ when native starch underwent carboxymethylation. SEM pictures showed that the smooth surface of native starch particles was mostly ruptured. XRD revealed that starch crystallinity was reduced after carboxymethylation. The viscosity of the mixture paste of carboxymethyl starch and sodium alginate (SA) was measured using a rotational viscometer. In addition, the applied effect of mixed paste in reactive dye printing was examined by assessing the fabric stiffness, color yield and sharp edge to the printed image in comparison with SA. And the results indicated that the mixed paste could partially replace SA as thickener in reactive dye printing. The study also showed that the method was low cost and eco-friendly and the product would have an extensive application in reactive dye printing. Copyright © 2012 Elsevier B.V. All rights reserved.

  8. Synthesis, Structural and Spectroscopic Characterization, and Reactivities of Mononuclear Cobalt(III)-Peroxo Complexes

    PubMed Central

    Cho, Jaeheung; Sarangi, Ritimukta; Kang, Hye Yeon; Lee, Jung Yoon; Kubo, Minoru; Ogura, Takashi; Solomon, Edward I.; Nam, Wonwoo

    2010-01-01

    Metal-dioxygen adducts are key intermediates detected in the catalytic cycles of dioxygen activation by metalloenzymes and biomimetic compounds. In this study, mononuclear cobalt(III)- peroxo complexes bearing tetraazamacrocyclic ligands, [Co(12-TMC)(O2)]+ and [Co(13-TMC)(O2)]+, were synthesized by reacting [Co(12-TMC)(CH3CN)]2+ and [Co(13-TMC)(CH3CN)]2+, respectively, with H2O2 in the presence of triethylamine. The mononuclear cobalt(III)-peroxo intermediates were isolated and characterized by various spectroscopic techniques and X-ray crystallography, and the structural and spectroscopic characterization demonstrated unambiguously that the peroxo ligand is bound in a side-on η2 fashion. The O-O bond stretching frequency of [Co(12-TMC)(O2)]+ and [Co(13- TMC)(O2)]+ was determined to be 902 cm−1 by resonance Raman spectroscopy. The structural properties of the CoO2 core in both complexes are nearly identical; the O-O bond distances of [Co(12-TMC)(O2)]+ and [Co(13-TMC)(O2)]+ were 1.4389(17) Å and 1.438(6) Å, respectively. The cobalt(III)-peroxo complexes showed reactivities in the oxidation of aldehydes and O2-transfer reactions. In the aldehyde oxidation reactions, the nucleophilic reactivity of the cobalt-peroxo complexes was significantly dependent on the ring size of the macrocyclic ligands, with the reactivity of [Co(13-TMC)(O2)]+ > [Co(12-TMC)(O2)]+. In the O2-transfer reactions, the cobalt(III)-peroxo complexes transferred the bound peroxo group to a manganese(II) complex, affording the corresponding cobalt(II) and manganese(III)- peroxo complexes. The reactivity of the cobalt-peroxo complexes in O2-transfer was also significantly dependent on the ring size of tetraazamacrocycles, and the reactivity order in the O2-transfer reactions was the same as that observed in the aldehyde oxidation reactions. PMID:21062059

  9. Pyro without fire: synthesis, structure, and reactivity of a dimeric vanadyl pyrophosphate coordination complex.

    PubMed

    Marino, Nadia; Hanson, Susan K; Müller, Peter; Doyle, Robert P

    2012-10-01

    The complex {[(V(IV)O)bipy(H(2)O)](2)(μ-P(2)O(7))}·3H(2)O (2) was readily obtained as a nanocrystalline powder by one-pot synthesis under mild conditions. Single crystals of 2 were grown at room temperature over 2 months, and its structure was determined. Fundamental catalytic activity was proven for this species by testing for oxidation of benzyl alcohol in air.

  10. Monitoring Immune System Function and Reactivation of Latent Viruses in the Artificial Gravity Pilot Study

    NASA Technical Reports Server (NTRS)

    Mehta, Satish; Crusian, Brian; Pierson, Duane; Sams, Clarence; Stowe, Raymond

    2007-01-01

    Numerous studies have indicated that dysregulation of the immune system occurs during or after spaceflight. Using 21 day -6 deg. head-down tilt bed rest as a spaceflight analog, this study describes the effects of artificial gravity as a daily countermeasure on immunity, stress and reactivation of clinically important latent herpes viruses. The specific aims were to evaluate psychological and physiological stress, to determine the status of the immune system and to quantify reactivation of latent herpes viruses. Blood, saliva, and urine samples were collected from each participating subject at different times throughout the study. An immune assessment was performed on all treatment and control subjects that consisted of a comprehensive peripheral immunophenotype analysis, intracellular cytokine profiles and a measurement of T cell function. The treatment group displayed no differences throughout the course of the study with regards to peripheral leukocyte distribution, cytokine production or T cell function. Shedding of EBV and CMV was quantified by real time PCR in saliva and urine samples, respectively. There was no significant difference in CMV DNA in the treatment group as compared to the control group. EBV and VZV on the other hand showed a mild reactivation during the study. There were no significant differences in plasma cortisol between the control and treatment groups. In addition, no significant differences between antiviral antibody titers (EBV-VCA, -EA, -EBNA, CMV) or tetramer-positive (EBV, CMV) were found between the two groups. EBV DNA copies in blood were typically undetectable but never exceeded 1,500 copies per 10(exp 6) PBMCs. These data indicate that the artificial gravity countermeasure and the 21 day head-down tilt bed rest regimen had no observable adverse effect on immune function.

  11. Monitoring Immune System Function and Reactivation of Latent Viruses in the Artificial Gravity Pilot Study

    NASA Technical Reports Server (NTRS)

    Mehta, Satish K.; Crucian, Brian; Pierson, Duane L.; Sams, Clarence; Stowe, Raymond P.

    2007-01-01

    Numerous studies have indicated that dysregulation of the immune system occurs during or after spaceflight. Using 21 day -6 degrees head-down tilt bed rest as a spaceflight analog, this study describes the effects of artificial gravity (AG) as a daily countermeasure on immunity, stress and reactivation of clinically important latent herpes viruses. The specific aims were to evaluate psychological and physiological stress, to determine the status of the immune system, and to quantify reactivation of latent herpes viruses. Blood, saliva, and urine samples were collected from each participating subject at different times throughout the study. An immune assessment was performed on all treatment and control subjects that consisted of a comprehensive peripheral immunophenotype analysis, intracellular cytokine profiles and a measurement of T cell function. The treatment group displayed no differences throughout the course of the study with regards to peripheral leukocyte distribution, cytokine production or T cell function. Shedding of Epstein barr virus (EBV), Cytomegalovirus (CMV), and Varicella zoster virus (VZV) was quantified by real time PCR in saliva and urine samples, respectively. There was no significant difference in CMV DNA in the treatment group as compared to the control group. EBV and VZV on the other hand showed a mild reactivation during the study. There were no significant differences in cortisol between the control and treatment groups. In addition, no significant differences between antiviral antibody titers (EBV-VCA, -EA, -EBNA, CMV) or tetramer-positive (EBV, CMV) were found between the two groups. EBV DNA copies in blood were typically undetectable but never exceeded 1,500 copies per 106 PBMCs. Overall, these data indicate that the artificial gravity countermeasure and the 21 day head-down tilt bed rest regimen had no observable adverse effect on immune function.

  12. [Inhibition of protein synthesis during associative memory reactivation produces reversible or irreversible amnesia in the snail Helix lucorum].

    PubMed

    Solntseva, S V; Nikitin, V P; Kozyrev, S A; Shevelkin, A V; Lagutin, A V; Sherstnev, V V

    2006-09-01

    Effects of protein synthesis inhibitors on reactivation processes of food aversion conditioning were inverstigated in snail Helix lucorum. Protein synthesis inhibitor (PSI, anisomycin, 0.4 mg, or cycloheximede, 0.6 mg) was injected into snail body cavity 24 hours after 3-day training; then conditioned stimulus (banana) was presented and memory was tested. It was found that 2.5-3 hours after first reminding, associative food conditioning was suppressed, recovering of the conditioning was observed 4.5-5.5 hours after first reminding. In other group of snails, PSI injections were single (1.8 mg) or triple (0.6 mg with 2-hour interval). Reminding stimulus was presented after each injection. In this case, suppression of food aversion conditioning was also observed 2.5-3 hours after first reminding, while amnesia in this case lasted over 30 days. Repeated training of the group of snails recovered the food aversion conditioning only partially. In control snails (saline instead of PSI or 3 injections of PSI without reminding), foot aversion conditioning was detected 30 days after first training. Thus we found that PSI effects during reminding of food aversion conditioning produced two phases amnesia: (1) the easily suppressed by PSI transient phase lasted 2-3 hours, and (2) irreversible phase, its suppression by high doses of PSI-initiated amnesia lasting over 1 month. Second phase of amnesia was not recovered after repeated training. It was suggested that reminding induced reconsolidation of initial memory. Its suppression by protein synthesis inhibitors results in erasing of memory trace and disturbs repeated consolidation.

  13. Anomeric effect revisited: Perspective from information-theoretic approach in density functional reactivity theory

    NASA Astrophysics Data System (ADS)

    Zhou, Xiayu; Yu, Donghai; Rong, Chunying; Lu, Tian; Liu, Shubin

    2017-09-01

    In this work, we apply the quantities from the information-theoretic approach in density functional reactivity theory to examine the origin and nature of the anomeric effect, which is the preference of heteroatomic substituents within the cyclohexane ring to be in the axial orientation rather than the sterically less hindered equatorial position. Using α-D-glucopyranose as an example, we confirmed its complex stereoelectronic origin. With Shannon entropy, Fisher information, GBP entropy, information gain, Onicescu information energy, and relative Renyi entropy, we are able to accurately account for the axial-equatorial energy difference in general, with the anomeric effect included as a special case.

  14. Thiol-reactive amphiphilic block copolymer for coating gold nanoparticles with neutral and functionable surfaces

    PubMed Central

    Chen, Hongwei; Zou, Hao; Paholak, Hayley J.; Ito, Masayuki; Qian, Wei; Che, Yong; Sun, Duxin

    2014-01-01

    Nanoparticles designed for biomedical applications are often coated with polymers containing reactive functional groups, such as –COOH and –NH2, to conjugate targeting ligands or drugs. However, introducing highly charged surfaces promotes binding of the nanoparticles to biomolecules in biological systems through ionic interactions, causing the nanoparticles to aggregate in biological environments and consequently undergo strong non-specific binding to off-target cells and tissues. Developing a unique polymer with neutral surfaces that can be further functionalized directly would be critical to develop suitable nanomaterials for nanomedicine. Here, we report a thiol-reactive amphiphilic block copolymer poly(ethylene oxide)-block-poly(pyridyldisulfide ethylmeth acrylate) (PEO-b-PPDSM) for coating gold nanoparticles (AuNPs). The resultant polymer-coated AuNPs have almost neutral surfaces with slightly negative zeta potentials from -10 to 0 mV over a wide pH range from 2 to 12. Although the zeta potential is close to zero we show that the PEO-b-PPDSM copolymer-coated AuNPs have both good stability in various physiological conditions and reduced non-specific adsorption of proteins/biomolecules. Because of the multiple pyridyldisulfide groups on the PPDSM block, these individually dispersed nanocomplexes with an overall hydrodynamic size around 43.8 nm can be directly functionalized via disulfide-thiol exchange chemistry. PMID:24729795

  15. Executive Functioning, Cortisol Reactivity, and Symptoms of Psychopathology in Girls with Premature Adrenarche

    PubMed Central

    Sontag-Padilla, Lisa M.; Dorn, Lorah D.; Tissot, Abbigail; Susman, Elizabeth J.; Beers, Sue R.; Rose, Susan R.

    2012-01-01

    The study examined the interaction between early maturational timing [as measured by premature adrenarche (PA)] and executive functioning and cortisol reactivity on symptoms of psychopathology. The study included 76 girls aged 6 through 8 years (mean = 7.50; SD = .85) with PA (n = 40) and on-time adrenarche (n = 36). Girls completed a battery of psychological and neuropsychological tests and blood sampling for cortisol. Parents completed the Child Behavior Checklist. Results demonstrated that girls with PA with lower levels of executive functioning had higher externalizing and anxious symptoms compared to other girls. Additionally, girls with PA who demonstrated increases in serum cortisol had higher externalizing symptoms than those with stable patterns. Finally, girls with PA who demonstrated decreases in cortisol reported higher depressive symptoms. Findings from this study provide important information concerning the impact of cognitive functioning and stress reactivity on adjustment to early maturation in girls with PA. Results of this research may inform screening and intervention efforts for girls who may be at greatest risk for emotional and behavioral problems as a result of early maturation. PMID:22293005

  16. A miniaturized technique for assessing protein thermodynamics and function using fast determination of quantitative cysteine reactivity.

    PubMed

    Isom, Daniel G; Marguet, Philippe R; Oas, Terrence G; Hellinga, Homme W

    2011-04-01

    Protein thermodynamic stability is a fundamental physical characteristic that determines biological function. Furthermore, alteration of thermodynamic stability by macromolecular interactions or biochemical modifications is a powerful tool for assessing the relationship between protein structure, stability, and biological function. High-throughput approaches for quantifying protein stability are beginning to emerge that enable thermodynamic measurements on small amounts of material, in short periods of time, and using readily accessible instrumentation. Here we present such a method, fast quantitative cysteine reactivity, which exploits the linkage between protein stability, sidechain protection by protein structure, and structural dynamics to characterize the thermodynamic and kinetic properties of proteins. In this approach, the reaction of a protected cysteine and thiol-reactive fluorogenic indicator is monitored over a gradient of temperatures after a short incubation time. These labeling data can be used to determine the midpoint of thermal unfolding, measure the temperature dependence of protein stability, quantify ligand-binding affinity, and, under certain conditions, estimate folding rate constants. Here, we demonstrate the fQCR method by characterizing these thermodynamic and kinetic properties for variants of Staphylococcal nuclease and E. coli ribose-binding protein engineered to contain single, protected cysteines. These straightforward, information-rich experiments are likely to find applications in protein engineering and functional genomics.

  17. Blood oxygen-level dependent functional assessment of cerebrovascular reactivity: Feasibility for intraoperative 3 Tesla MRI.

    PubMed

    Fierstra, Jorn; Burkhardt, Jan-Karl; van Niftrik, Christiaan Hendrik Bas; Piccirelli, Marco; Pangalu, Athina; Kocian, Roman; Neidert, Marian Christoph; Valavanis, Antonios; Regli, Luca; Bozinov, Oliver

    2017-02-01

    To assess the feasibility of functional blood oxygen-level dependent (BOLD) MRI to evaluate intraoperative cerebrovascular reactivity (CVR) at 3 Tesla field strength. Ten consecutive neurosurgical subjects scheduled for a clinical intraoperative MRI examination were enrolled in this study. In addition to the clinical protocol a BOLD sequence was implemented with three cycles of 44 s apnea to calculate CVR values on a voxel-by-voxel basis throughout the brain. The CVR range was then color-coded and superimposed on an anatomical volume to create high spatial resolution CVR maps. Ten subjects (mean age 34.8 ± 13.4; 2 females) uneventfully underwent the intraoperative BOLD protocol, with no complications occurring. Whole-brain CVR for all subjects was (mean ± SD) 0.69 ± 0.42, whereas CVR was markedly higher for tumor subjects as compared to vascular subjects, 0.81 ± 0.44 versus 0.33 ± 0.10, respectively. Furthermore, color-coded functional maps could be robustly interpreted for a whole-brain assessment of CVR. We demonstrate that intraoperative BOLD MRI is feasible in creating functional maps to assess cerebrovascular reactivity throughout the brain in subjects undergoing a neurosurgical procedure. Magn Reson Med 77:806-813, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  18. Thiol-reactive amphiphilic block copolymer for coating gold nanoparticles with neutral and functionable surfaces.

    PubMed

    Chen, Hongwei; Zou, Hao; Paholak, Hayley J; Ito, Masayuki; Qian, Wei; Che, Yong; Sun, Duxin

    2014-04-21

    Nanoparticles designed for biomedical applications are often coated with polymers containing reactive functional groups, such as -COOH and -NH2, to conjugate targeting ligands or drugs. However, introducing highly charged surfaces promotes binding of the nanoparticles to biomolecules in biological systems through ionic interactions, causing the nanoparticles to aggregate in biological environments and consequently undergo strong non-specific binding to off-target cells and tissues. Developing a unique polymer with neutral surfaces that can be further functionalized directly would be critical to develop suitable nanomaterials for nanomedicine. Here, we report a thiol-reactive amphiphilic block copolymer poly(ethylene oxide)-block-poly(pyridyldisulfide ethylmeth acrylate) (PEO-b-PPDSM) for coating gold nanoparticles (AuNPs). The resultant polymer-coated AuNPs have almost neutral surfaces with slightly negative zeta potentials from -10 to 0 mV over a wide pH range from 2 to 12. Although the zeta potential is close to zero we show that the PEO-b-PPDSM copolymer-coated AuNPs have both good stability in various physiological conditions and reduced non-specific adsorption of proteins/biomolecules. Because of the multiple pyridyldisulfide groups on the PPDSM block, these individually dispersed nanocomplexes with an overall hydrodynamic size around 43.8 nm can be directly functionalized via disulfide-thiol exchange chemistry.

  19. Reactive Muscle Firing of Anterior Cruciate Ligament-Injured Females During Functional Activities

    PubMed Central

    Swanik, C. Buz; Lephart, Scott M.; Giraldo, Jorge L.; DeMont, Richard G.; Fu, Freddie H.

    1999-01-01

    Objective: The high incidence of noncontact anterior cruciate ligament (ACL) injuries in females has attracted research to investigate the capacity of muscles to reflexively protect the knee joint from capsuloligamentous injury. Numerous reflex pathways link mechanoreceptors in the ACL with contractile fibers in the quadriceps and hamstring muscles. Loads placed on the ACL modify reactive muscle activity through the feed-back process of neuromuscular control and are critical for dynamic muscular stabilization. Noncontact ACL injuries may be the result of aberrations in reactive muscle firing patterns. Therefore, compensatory muscle activation strategies must be employed if functional stability is to be restored after injury or surgical reconstruction. The purpose of our study was to compare the amplitude of reactive muscle activity in females with ACL-deficient (ACLD), ACL-reconstructed (ACLR), and control knees during functional activities. Design and Setting: Female volunteer subjects were stratified into groups based on the status of their ACLs. Each subject performed 4 functional activities, bilaterally, during a single test session. Subjects: Twenty-four female subjects participated in this study (ACLD = 6, ACLR = 12, control = 6). Measurements: Integrated electromyographic (IEMG) data were collected with surface electrodes from the vastus medialis, vastus lateralis, medial hamstring, and lateral hamstring during downhill walking (15°, 0.92 m/s), level running (2.08 m/s), and hopping and landing from a jump (20.3 cm). IEMG was normalized to the mean amplitude of 3 to 6 consecutive test repetitions. The mean area and peak IEMG of a 250-millisecond period after ground contact was used to represent reactive muscle activity. Side-to-side differences were determined using dependent t tests, and group differences were determined using a one-way analysis of variance. Results: During running, the ACLD group demonstrated significantly greater area and peak IEMG

  20. Synthesis and in-vitro reactivation screening of imidazolium aldoximes as reactivators of sarin and VX-inhibited human acetylcholinesterase (hAChE).

    PubMed

    Sharma, Rahul; Gupta, Bhanushree; Sahu, Arvind Kumar; Acharya, Jyotiranjan; Satnami, Manmohan L; Ghosh, Kallol K

    2016-11-25

    Post-treatment of organophosphate (OP) poisoning involves the application of oxime reactivator as an antidote. Structurally different oximes are widely studied to examine their kinetic and mechanistic behavior against OP-inhibited cholinesterase enzyme. A series of structurally related 1,3-disubstituted-2-[(hydroxyiminomethyl)alkyl]imidazolium halides (5a-5e, 9a-9c) were synthesized and further evaluated for their in-vitro reactivation ability to reactivate sarin- and VX-inhibited human acetylcholinesterase (hAChE). The observed results were compared with the reactivation efficacy of standard reactivators; 2-PAM, obidoxime and HI-6. Amongst the synthesized oximes, 5a, 9a and 9b were found to be most potent reactivators against sarin-inhibited hAChE while in case of VX only 9a exhibited comparable reactivity with 2-PAM. Incorporation of pyridinium ring to the imidazole ring resulted in substantial increase in the reactivation strength of prepared reactivator. Physicochemical properties of synthesized reactivators have also been evaluated.

  1. Hodgkin-Reed-Sternberg Cells in Classical Hodgkin Lymphoma Show Alterations of Genes Encoding the NADPH Oxidase Complex and Impaired Reactive Oxygen Species Synthesis Capacity

    PubMed Central

    Sosna, Justyna; Döring, Claudia; Klapper, Wolfram; Küppers, Ralf; Böttcher, Sebastian; Adam, Dieter; Siebert, Reiner; Schütze, Stefan

    2013-01-01

    The membrane bound NADPH oxidase involved in the synthesis of reactive oxygen species (ROS) is a multi-protein enzyme encoded by CYBA, CYBB, NCF1, NCF2 and NCF4 genes. Growing evidence suggests a role of ROS in the modulation of signaling pathways of non-phagocytic cells, including differentiation and proliferation of B-cell progenitors. Transcriptional downregulation of the CYBB gene has been previously reported in cell lines of the B-cell derived classical Hodgkin lymphoma (cHL). Thus, we explored functional consequences of CYBB downregulation on the NADPH complex. Using flow cytometry to detect and quantify superoxide anion synthesis in cHL cell lines we identified recurrent loss of superoxide anion production in all stimulated cHL cell lines in contrast to stimulated non-Hodgkin lymphoma cell lines. As CYBB loss proved to exert a deleterious effect on the NADPH oxidase complex in cHL cell lines, we analyzed the CYBB locus in Hodgkin and Reed-Sternberg (HRS) cells of primary cHL biopsies by in situ hybridisation and identified recurrent deletions of the gene in 8/18 cases. Immunohistochemical analysis to 14 of these cases revealed a complete lack of detectable CYBB protein expression in all HRS cells in all cases studied. Moreover, by microarray profiling of cHL cell lines we identified additional alterations of NADPH oxidase genes including CYBA copy number loss in 3/7 cell lines and a significant downregulation of the NCF1 transcription (p=0.006) compared to normal B-cell subsets. Besides, NCF1 protein was significantly downregulated (p<0.005) in cHL compared to other lymphoma cell lines. Together this findings show recurrent alterations of the NADPH oxidase encoding genes that result in functional inactivation of the enzyme and reduced production of superoxide anion in cHL. PMID:24376854

  2. Effects of gravity on combustion synthesis of functionally graded biomaterials

    NASA Astrophysics Data System (ADS)

    Castillo, M.; Moore, J. J.; Schowengerdt, F. D.; Ayers, R. A.; Zhang, X.; Umakoshi, M.; Yi, H. C.; Guigne, J. Y.

    2003-07-01

    Combustion synthesis, or self-propagating, high temperature synthesis is currently being used at the Colorado School of Mines to produce advanced materials for biomedical applications. These biomaterials include ceramic, intermetallic, and metal-matrix composites for applications ranging from structural to oxidation- and wear-resistant materials, e.g., TiC-Ti, TiC-Cr 3C 2, MOSi 2-SiC, NiAl-TiB 2, to engineered porous composites, e.g., B 4C-Al 2O 3, Ti-TiB x, Ni-Ti, Ca 3(P0 4) 2 and glass-ceramic composites, e.g., CaO-SiO 2-BaO-Al 2O 3-TiB 2. The goal of the functionally graded biomaterials project is to develop new materials, graded in porosity and composition, which will combine the desirable mechanical properties of implant, e.g., NiTi, with the bone-growth enhancement properties of porous biodegradable ceramics, e.g., Ca 3(PO 4) 2. Recent experiments on the NASA parabolic flight (KC-135) aircraft have shown that gravity plays an important role in controlling the structure and properties of materials produced by combustion synthesis. The results of these studies, which will be presented at the conference, will provide valuable input to the design of experiments to be done in Space-DRUMS TM, a containerless materials processing facility scheduled to be placed on the International Space Station in 2003.

  3. Effects of gravity on combustion synthesis of functionally graded biomaterials

    NASA Astrophysics Data System (ADS)

    Moore, J.; Schowengerdt, F.; Ayers, R.; Castillo, M.; Zhang, X.; Umakoshi, U.; Yi, C.; Guigne, J.

    Combustion synthesis, or self-propagating, high temperature synthesis (SHS) is currently being used at the Colorado School of Mines to produce advanced materials for biomedical applications. These biomaterials include ceramic, intermetallic, and metal-matrix composites for applications ranging from structural to oxidation- and wear-resistant materials, e.g., TiC-Ti, TiC-Cr3 C2 , MoSi2 - SiC, NiAl-TiB2 , to engineered porous composites, e.g., B4 C-A l2 O3 , Ti-TiBx , Ni-Ti, Ca 3 (PO4 )2 and glass- ceramic composites, e.g., CaO-SiO2 - B a O-A l2 O3 -T i B2 . The goal of the functionally graded biomaterials project is to develop new materials, graded in porosity and composition, which will combine the desirable mechanical properties of implant, e.g., NiTi, with the bone-growth enhancement properties of porous biodegradable ceramics, e.g., Ca 3 (PO4 )2 . Recent experiments on the NASA parabolic flight (KC- 135) aircraft have shown that gravity plays an important role in controlling the structure and properties of materials produced by combustion synthesis. The results of these studies, which will be presented at the conference, will provide valuable input to the design of experiments to be done in Space-DRUMSTM, a containerless materials processing facility scheduled to be placed on the International Space Station in 2003.

  4. Synthesis and Characterization of Functionalized Metal-organic Frameworks

    PubMed Central

    Karagiaridi, Olga; Bury, Wojciech; Sarjeant, Amy A.; Hupp, Joseph T.; Farha, Omar K.

    2014-01-01

    Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy. PMID:25225784

  5. Synthesis and characterization of functionalized metal-organic frameworks.

    PubMed

    Karagiaridi, Olga; Bury, Wojciech; Sarjeant, Amy A; Hupp, Joseph T; Farha, Omar K

    2014-09-05

    Metal-organic frameworks have attracted extraordinary amounts of research attention, as they are attractive candidates for numerous industrial and technological applications. Their signature property is their ultrahigh porosity, which however imparts a series of challenges when it comes to both constructing them and working with them. Securing desired MOF chemical and physical functionality by linker/node assembly into a highly porous framework of choice can pose difficulties, as less porous and more thermodynamically stable congeners (e.g., other crystalline polymorphs, catenated analogues) are often preferentially obtained by conventional synthesis methods. Once the desired product is obtained, its characterization often requires specialized techniques that address complications potentially arising from, for example, guest-molecule loss or preferential orientation of microcrystallites. Finally, accessing the large voids inside the MOFs for use in applications that involve gases can be problematic, as frameworks may be subject to collapse during removal of solvent molecules (remnants of solvothermal synthesis). In this paper, we describe synthesis and characterization methods routinely utilized in our lab either to solve or circumvent these issues. The methods include solvent-assisted linker exchange, powder X-ray diffraction in capillaries, and materials activation (cavity evacuation) by supercritical CO2 drying. Finally, we provide a protocol for determining a suitable pressure region for applying the Brunauer-Emmett-Teller analysis to nitrogen isotherms, so as to estimate surface area of MOFs with good accuracy.

  6. Common and unique neural networks for proactive and reactive response inhibition revealed by independent component analysis of functional MRI data.

    PubMed

    van Belle, Janna; Vink, Matthijs; Durston, Sarah; Zandbelt, Bram B

    2014-12-01

    Response inhibition involves proactive and reactive modes. Proactive inhibition is goal-directed, triggered by warning cues, and serves to restrain actions. Reactive inhibition is stimulus-driven, triggered by salient stop-signals, and used to stop actions completely. Functional MRI studies have identified brain regions that activate during proactive and reactive inhibition. It remains unclear how these brain regions operate in functional networks, and whether proactive and reactive inhibition depend on common networks, unique networks, or a combination. To address this we analyzed a large fMRI dataset (N=65) of a stop-signal task designed to measure proactive and reactive inhibition, using independent component analysis (ICA). We found 1) three frontal networks that were associated with both proactive and reactive inhibition, 2) one network in the superior parietal lobe, which also included dorsal premotor cortex and left putamen, that was specifically associated with proactive inhibition, and 3) two right-lateralized frontal and fronto-parietal networks, including the right inferior frontal gyrus and temporoparietal junction as well as a bilateral fronto-temporal network that were uniquely associated with reactive inhibition. Overlap between networks was observed in dorsolateral prefrontal and parietal cortices. Taken together, we offer a new perspective on the neural underpinnings of inhibitory control, by showing that proactive inhibition and reactive inhibition are supported by a group of common and unique networks that appear to integrate and interact in frontoparietal areas.

  7. Synthesis of Highly Reactive Subnano-sized Zero-valent Iron using Smectite Clay Templates

    PubMed Central

    Gu, Cheng; Jia, Hanzhang; Li, Hui; Teppen, Brian J.; Boyd, Stephen A.

    2010-01-01

    A novel method was developed for synthesizing subnano-sized zero-valent iron (ZVI) using smectite clay layers as templates. Exchangeable Fe(III) cations compensating the structural negative charges of smectites were reduced with NaBH4, resulting in the formation of ZVI. The unique structure of smectite clay, in which isolated exchangeable Fe(III) cations reside near the sites of structural negative charges, inhibited the agglomeration of ZVI resulting in the formation of discrete regions of subnanoscale ZVI particles in the smectite interlayer regions. X-ray diffraction revealed an interlayer spacing of ~ 5 Å. The non-structural iron content of this clay yields a calculated ratio of two atoms of ZVI per three cation exchange sites, in full agreement with the XRD results since the diameter of elemental Fe is 2.5 Å. The clay-templated ZVI showed superior reactivity and efficiency compared to other previously reported forms of ZVI as indicated by the reduction of nitrobenzene; structural Fe within the aluminosilicate layers was nonreactive. At a 1:3 molar ratio of nitrobenzene:non-structural Fe, a reaction efficiency of 83% was achieved, and over 80% of the nitrobenzene was reduced within one minute. These results confirm that non-structural Fe from Fe(III)-smectite was reduced predominantly to ZVI which was responsible for the reduction of nitrobenzene to aniline. This new form of subnano-scale ZVI may find utility in the development of remediation technologies for persistent environmental contaminants, e.g. as components of constructed reactive domains such as reactive caps for contaminated sediments. PMID:20446730

  8. ZnO thin film synthesis by reactive radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Şenay, Volkan; Pat, Suat; Korkmaz, Şadan; Aydoğmuş, Tuna; Elmas, Saliha; Özen, Soner; Ekem, Naci; Balbağ, M. Zafer

    2014-11-01

    In this study, ZnO thin films were deposited on glass substrates by reactive RF magnetron sputtering method at argon-oxygen gas mixing (1:1) atmosphere. Some properties of the synthesized films were investigated by interferometry, UV-vis spectrophotometer, atomic force microscopy, and tensiometer. Tauc method was adopted to estimate the optical band gaps. The band gaps of the deposited films were affected by film thickness. We concluded that the surface composition plays a substantial role in the values of the band gaps. Nanocrystalline structures were detected in all produced samples.

  9. Solvent-Free Synthesis and Fluorescence of a Thiol-Reactive Sensor for Undergraduate Organic Laboratories.

    PubMed

    Patterson, Anastasia L; May, Mary D; Visser, Bryan J; Kislukhin, Alexander A; Vosburg, David A

    2013-12-10

    A green organic laboratory experiment was developed in which students synthesize a sensor for thiols using a microscale, solventless Diels-Alder reaction at room temperature or 37 °C. The molecular probe is easily purified by column chromatography in a Pasteur pipet and characterized by thin-layer chromatography and NMR spectroscopy. The thiol-reactive sensor becomes intensely fluorescent upon exposure to thiols from N-acetylcysteine, bovine serum albumin, or human hair (pretreated with a reducing agent to reveal cysteine thiols in α-keratin). This fluorescence is observable even with micrograms of probe.

  10. Solvent-Free Synthesis and Fluorescence of a Thiol-Reactive Sensor for Undergraduate Organic Laboratories

    PubMed Central

    Patterson, Anastasia L.; May, Mary D.; Visser, Bryan J.; Kislukhin, Alexander A.; Vosburg, David A.

    2013-01-01

    A green organic laboratory experiment was developed in which students synthesize a sensor for thiols using a microscale, solventless Diels–Alder reaction at room temperature or 37 °C. The molecular probe is easily purified by column chromatography in a Pasteur pipet and characterized by thin-layer chromatography and NMR spectroscopy. The thiol-reactive sensor becomes intensely fluorescent upon exposure to thiols from N-acetylcysteine, bovine serum albumin, or human hair (pretreated with a reducing agent to reveal cysteine thiols in α-keratin). This fluorescence is observable even with micrograms of probe. PMID:24415795

  11. Synthesis of Hydrodipyrrins Tailored for Reactivity at the 1- and 9-Positions

    PubMed Central

    Kim, Han-Je; Dogutan, Dilek Kiper; Ptaszek, Marcin; Lindsey, Jonathan S.

    2007-01-01

    A collection of 33 hydrodipyrrins (9 targets, 21 intermediates, and 3 byproducts) has been prepared. The hydrodipyrrins (dihydrodipyrrins, tetrahydrodipyrrins, and hexahydrodipyrrins) contain a pyrrole ring and a geminal-dimethyl substituted 1-pyrroline (or pyrrolidine) ring. The α-substituents on the pyrrole ring (H, Br, CHO) and pyrroline ring (H, CH3, CH(OR)2, OMe, SMe) provide different reactivity combinations (Nu−, E+) and 0, 1, or 2 carbon atoms (which can give rise to the bridging meso-carbons in hydroporphyrins). Straightforward access to various hydrodipyrrins should facilitate development of syntheses of diverse hydroporphyrins. PMID:17464365

  12. Simple Platform Method for the Synthesis of Densely Functionalized Microgels by Modification of Active Ester Latex Particles.

    PubMed

    Han, Kang; Tiwari, Rahul; Heuser, Thomas; Walther, Andreas

    2016-08-01

    This study reports a simple and versatile synthesis route for the preparation of highly uniform and densely functionalized aqueous microgels by modification of latex particles composed of an active ester monomer (pentafluorophenyl acrylate; PFPA). The hydrophobic nature of the PFPA allows synthesizing very uniform latex particles via emulsion polymerization, whose size can be controlled by the surfactant concentration, while the degree of crosslinking is a function of the added crosslinker. The high reactivity of the PFPA groups toward nucleophilic substitution delivers a platform method to synthesize functional microgels by reaction with functional amines. This study demonstrates this process for the dense functionalization of the entire particle with an amine carrying a pH-responsive unit. This study further describes the influence of the crosslinking degree on the ability for swelling of the resulting microgels in aqueous dispersion.

  13. Synthesis of functional acetylene derivatives from calcium carbide.

    PubMed

    Lin, Zhewang; Yu, Dingyi; Sum, Yin Ngai; Zhang, Yugen

    2012-04-01

    AHA Erlebnis: CaC(2), used to produce acetylene until several decades ago, is re-emerging as a cheap, sustainable resource synthesized from coal and lignocellulosic biomass. We report efficient catalytic protocols for the synthesis of functional acetylene derivatives from CaC(2) through aldehyde, alkyne, and amine (AAA) as well as alkyne, haloalkane, and amine (AHA) couplings, and in addition demonstrate its use in click and Sonogashira chemistry, showing that calcium carbide is a sustainable and cost-efficient carbon source.

  14. Boron-based nanostructures: Synthesis, functionalization, and characterization

    NASA Astrophysics Data System (ADS)

    Bedasso, Eyrusalam Kifyalew

    Boron-based nanostructures have not been explored in detail; however, these structures have the potential to revolutionize many fields including electronics and biomedicine. The research discussed in this dissertation focuses on synthesis, functionalization, and characterization of boron-based zero-dimensional nanostructures (core/shell and nanoparticles) and one-dimensional nanostructures (nanorods). The first project investigates the synthesis and functionalization of boron-based core/shell nanoparticles. Two boron-containing core/shell nanoparticles, namely boron/iron oxide and boron/silica, were synthesized. Initially, boron nanoparticles with a diameter between 10-100 nm were prepared by decomposition of nido-decaborane (B10H14) followed by formation of a core/shell structure. The core/shell structures were prepared using the appropriate precursor, iron source and silica source, for the shell in the presence of boron nanoparticles. The formation of core/shell nanostructures was confirmed using high resolution TEM. Then, the core/shell nanoparticles underwent a surface modification. Boron/iron oxide core/shell nanoparticles were functionalized with oleic acid, citric acid, amine-terminated polyethylene glycol, folic acid, and dopamine, and boron/silica core/shell nanoparticles were modified with 3-(amino propyl) triethoxy silane, 3-(2-aminoethyleamino)propyltrimethoxysilane), citric acid, folic acid, amine-terminated polyethylene glycol, and O-(2-Carboxyethyl)polyethylene glycol. A UV-Vis and ATR-FTIR analysis established the success of surface modification. The cytotoxicity of water-soluble core/shell nanoparticles was studied in triple negative breast cancer cell line MDA-MB-231 and the result showed the compounds are not toxic. The second project highlights optimization of reaction conditions for the synthesis of boron nanorods. This synthesis, done via reduction of boron oxide with molten lithium, was studied to produce boron nanorods without any

  15. Synthesis and reactivity of a mono-sigma-aryl palladium(IV) fluoride complex.

    PubMed

    Ball, Nicholas D; Sanford, Melanie S

    2009-03-25

    This communication describes the rational design and synthesis of the remarkably stable Pd(IV) monoaryl fluoride complex (t-Bu-bpy)Pd(IV)(p-FC(6)H(4))(F)(2)(FHF) (t-Bu-bpy = 4,4'-di-tert-butyl-2,2'-bipyridine). This and related complexes undergo Ar-F bond formation in the presence of "F(+)" sources. This work serves as a foundation for the development of Pd(II/IV)-catalyzed coupling reactions to form aryl fluorides.

  16. Synthesis and characterization of core-shell acrylate based latex and study of its reactive blends.

    PubMed

    Liu, Xiang; Fan, Xiao-Dong; Tang, Min-Feng; Nie, Ying

    2008-03-01

    Techniques in resin blending are simple and efficient method for improving the properties of polymers, and have been used widely in polymer modification field. However, polymer latex blends such as the combination of latexes, especially the latexes with water-soluble polymers, were rarely reported. Here, we report a core-shell composite latex synthesized using methyl methacrylate (MMA), butyl acrylate (BA), 2-ethylhexyl acrylate (EHA) and glycidyl methacrylate (GMA) as monomers and ammonium persulfate and sodium bisulfite redox system as the initiator. Two stages seeded semi-continuous emulsion polymerization were employed for constructing a core-shell structure with P(MMA-co-BA) component as the core and P(EHA-co-GMA) component as the shell. Results of Transmission Electron Microscopy (TEM) and Dynamics Light Scattering (DLS) tests confirmed that the particles obtained are indeed possessing a desired core-shell structural character. Stable reactive latex blends were prepared by adding the latex with waterborne melamine-formaldehyde resin (MF) or urea-formaldehyde resin (UF). It was found that the glass transition temperature, the mechanical strength and the hygroscopic property of films cast from the latex blends present marked enhancements under higher thermal treatment temperature. It was revealed that the physical properties of chemically reactive latexes with core-shell structure could be altered via the change of crosslinking density both from the addition of crosslinkers and the thermal treatment.

  17. Synthesis and Characterization of Core-Shell Acrylate Based Latex and Study of Its Reactive Blends

    PubMed Central

    Liu, Xiang; Fan, Xiao-Dong; Tang, Min-Feng; Nie, Ying

    2008-01-01

    Techniques in resin blending are simple and efficient method for improving the properties of polymers, and have been used widely in polymer modification field. However, polymer latex blends such as the combination of latexes, especially the latexes with water-soluble polymers, were rarely reported. Here, we report a core-shell composite latex synthesized using methyl methacrylate (MMA), butyl acrylate (BA), 2-ethylhexyl acrylate (EHA) and glycidyl methacrylate (GMA) as monomers and ammonium persulfate and sodium bisulfite redox system as the initiator. Two stages seeded semi-continuous emulsion polymerization were employed for constructing a core-shell structure with P(MMA-co-BA) component as the core and P(EHA-co-GMA) component as the shell. Results of Transmission Electron Microscopy (TEM) and Dynamics Light Scattering (DLS) tests confirmed that the particles obtained are indeed possessing a desired core-shell structural character. Stable reactive latex blends were prepared by adding the latex with waterborne melamine-formaldehyde resin (MF) or urea-formaldehyde resin (UF). It was found that the glass transition temperature, the mechanical strength and the hygroscopic property of films cast from the latex blends present marked enhancements under higher thermal treatment temperature. It was revealed that the physical properties of chemically reactive latexes with core-shell structure could be altered via the change of crosslinking density both from the addition of crosslinkers and the thermal treatment. PMID:19325753

  18. Synthesis and reactivity studies of a manganese 'microperoxidase' containing b-type heme.

    PubMed

    Ryabova, Ekaterina S; Nordlander, Ebbe

    2005-04-07

    Mn(III)protoporphyrin IX-6(7)-gly-gly-his methyl ester (MnGGH) has been prepared by condensation of glycyl-glycyl-L-histidine methyl ester with the propionic side chains of Mn(III)protoporphyrin IX. It was characterised by mass spectrometry and UV/VIS spectroscopy. Stopped-flow spectrophotometry was used to study the reaction of the Mn 'microperoxidase' with hydrogen peroxide. The formation of active intermediates analogous to previously described metal-hydroperoxo (compound 0) and metal-oxo (compound I) intermediates of the 'natural' Fe(III) microperoxidase-8 and Mn(III) microperoxidase-8 was observed. The rate of formation of the MnGGH-based compound I analogue was found to increase dramatically with increasing pH. A steady-state kinetic analysis of the catalytic peroxidase activity of MnGGH towards K4[Fe(CN)6], L-tyrosine methyl ester, o-dianisidine, o-methoxyphenol and ascorbic acid showed that the peroxidase reaction proceeds via the formation of a microperoxidase-substrate complex followed by electron transfer from the substrate to the metal. The reactivity of MnGGH depends on the size and hydrophobicity of the substrate, and these properties appear to influence the rate of the electron transfer, which is the rate-limiting step for the whole process. MnGGH showed higher reactivity towards reducing substrates than its Fe(iii) analogue.

  19. Synthesis of novel reactive N-halamine precursors and application in antimicrobial cellulose

    NASA Astrophysics Data System (ADS)

    Jiang, Zhiming; Ma, Kaikai; Du, Jinmei; Li, Rong; Ren, Xuehong; Huang, T. S.

    2014-01-01

    2,4,6-Trichloro-s-triazine has been used as one of the important linkers of reactive dyes for textiles such as cellulosic fibers. N-Halamine precursors could be bonded to a triazine-based linker by the chloride displacement reaction, and the synthesized compounds could attach to cotton fabrics by covalent bonds through a reactive dyeing process. In this study, two novel antimicrobial N-halamine precursors, 2,2,6,6-tetramethyl-4-piperidinol-s-trizine (TMPT) and 4-(4-(2,2,6,6-tetramethyl-4-piperidinol)-6-chloro-1,3,5-triazinylamino)-benzenesulfonate (BTMPT), were synthesized and used to coat cotton fabrics. The synthesized s-triazine-based N-halamine precursors react with cellulose to produce biocidal cellulosic fibers upon exposure to diluted household bleach. The coated fabrics were characterized by FT-IR and SEM. The chlorinated treated cotton swatches demonstrated excellent antimicrobial properties against S. aureus (Gram-positive) and E. coli O157:H7 (Gram-negative) with short contact times. Washing test and UVA light test showed that chlorinated BTMPT-coated cotton fabrics were more stable than TMPT-coated cotton fabrics. Compared to the traditional pad-dry-cure technique to produce antimicrobial textiles, the novel process in this study has advantages of saving energy and maintaining tensile strength of fabrics.

  20. Evaluating frontier orbital energy and HOMO/LUMO gap with descriptors from density functional reactivity theory.

    PubMed

    Huang, Ying; Rong, Chunying; Zhang, Ruiqin; Liu, Shubin

    2017-01-01

    Wave function theory (WFT) and density functional theory (DFT)-the two most popular solutions to electronic structure problems of atoms and molecules-share the same origin, dealing with the same subject yet using distinct methodologies. For example, molecular orbitals are artifacts in WFT, whereas in DFT, electron density plays the dominant role. One question that needs to be addressed when using these approaches to appreciate properties related to molecular structure and reactivity is if there is any link between the two. In this work, we present a piece of strong evidence addressing that very question. Using five polymeric systems as illustrative examples, we reveal that using quantities from DFT such as Shannon entropy, Fisher information, Ghosh-Berkowitz-Parr entropy, Onicescu information energy, Rényi entropy, etc., one is able to accurately evaluate orbital-related properties in WFT like frontier orbital energies and the HOMO (highest occupied molecular orbital)/LUMO (lowest unoccupied molecular orbital) gap. We verified these results at both the whole molecule level and the atoms-in-molecules level. These results provide compelling evidence suggesting that WFT and DFT are complementary to each other, both trying to comprehend the same properties of the electronic structure and molecular reactivity from different perspectives using their own characteristic vocabulary. Hence, there should be a bridge or bridges between the two approaches.

  1. Origin of molecular conformational stability: Perspectives from molecular orbital interactions and density functional reactivity theory

    SciTech Connect

    Liu, Shubin E-mail: schauer@unc.edu; Schauer, Cynthia K. E-mail: schauer@unc.edu

    2015-02-07

    To have a quantitative understanding about the origin of conformation stability for molecular systems is still an unaccomplished task. Frontier orbital interactions from molecular orbital theory and energy partition schemes from density functional reactivity theory are the two approaches available in the literature that can be used for this purpose. In this work, we compare the performance of these approaches for a total of 48 simple molecules. We also conduct studies to flexibly bend bond angles for water, carbon dioxide, borane, and ammonia molecules to obtain energy profiles for these systems over a wide range of conformations. We find that results from molecular orbital interactions using frontier occupied orbitals such as the highest occupied molecular orbital and its neighbors are only qualitatively, at most semi-qualitatively, trustworthy. To obtain quantitative insights into relative stability of different conformations, the energy partition approach from density functional reactivity theory is much more reliable. We also find that the electrostatic interaction is the dominant descriptor for conformational stability, and steric and quantum effects are smaller in contribution but their contributions are indispensable. Stable molecular conformations prefer to have a strong electrostatic interaction, small molecular size, and large exchange-correlation effect. This work should shed new light towards establishing a general theoretical framework for molecular stability.

  2. Sulfur dioxide and ammonium sulfate effects on pulmonary function and bronchial reactivity in human subjects.

    PubMed

    Kulle, T J; Sauder, L R; Shanty, F; Kerr, H D; Farrell, B P; Miller, W R; Milman, J H

    1984-03-01

    The effect of exposures to 1 ppm sulfur dioxide (SO2) and 500 micrograms/m3 respirable ammonium sulfate [(NH4)2SO4] was studied in 20 nonsmoking subjects to determine if a response can be measured at these atmospheric levels and if the response is additive or synergistic. Four-hour separate and combined exposures were employed. Each subject acted as his or her own control and performed two light-to-moderate exercise stints (612 kg-m/min) for 15 minutes on each day's confinement in the environmental chamber. Pulmonary function tests (body plethysmography and spirometry) and bronchial reactivity to methacholine were performed to assess the response of these exposures. No significant changes in pulmonary function or bronchial reactivity were observed in the individual exposures [(NH4)2SO4 or SO2], the combined exposure [(NH4)2SO4 and SO2], or 24 hours post-exposure. This study design and the observed results did not demonstrate any readily apparent risk to healthy subjects with these exposures. Since no significant changes were measured, it was not possible to conclude if these two pollutants in combination produce an additive or synergistic response.

  3. Origin of molecular conformational stability: perspectives from molecular orbital interactions and density functional reactivity theory.

    PubMed

    Liu, Shubin; Schauer, Cynthia K

    2015-02-07

    To have a quantitative understanding about the origin of conformation stability for molecular systems is still an unaccomplished task. Frontier orbital interactions from molecular orbital theory and energy partition schemes from density functional reactivity theory are the two approaches available in the literature that can be used for this purpose. In this work, we compare the performance of these approaches for a total of 48 simple molecules. We also conduct studies to flexibly bend bond angles for water, carbon dioxide, borane, and ammonia molecules to obtain energy profiles for these systems over a wide range of conformations. We find that results from molecular orbital interactions using frontier occupied orbitals such as the highest occupied molecular orbital and its neighbors are only qualitatively, at most semi-qualitatively, trustworthy. To obtain quantitative insights into relative stability of different conformations, the energy partition approach from density functional reactivity theory is much more reliable. We also find that the electrostatic interaction is the dominant descriptor for conformational stability, and steric and quantum effects are smaller in contribution but their contributions are indispensable. Stable molecular conformations prefer to have a strong electrostatic interaction, small molecular size, and large exchange-correlation effect. This work should shed new light towards establishing a general theoretical framework for molecular stability.

  4. Density Functional Reactivity Theory Characterizes Charge Separation Propensity in Proton-Coupled Electron Transfer Reactions

    SciTech Connect

    Liu, Shubin; Ess, Daniel H.; Schauer, Cynthia

    2011-04-20

    Proton-coupled electron transfer (PCET) reactions occur in many biological and artificial solar energy conversion processes. In these reactions the electron is often transferred to a site distant to the proton acceptor site. In this work, we employ the dual descriptor and the electrophilic Fukui function from density functional reactivity theory (DFRT) to characterize the propensity for an electron to be transferred to a site other than the proton acceptor site. The electrophilic regions of hydrogen bond or van der Waal reactant complexes were examined using these DFRT descriptors to determine the region of space to which the electron is most likely to be transferred. This analysis shows that in PCET reactions the electrophilic region of the reactant complex does not include the proton acceptor site.

  5. Physical functioning related to C-reactive protein and fibrinogen levels in mid-life women

    PubMed Central

    Tomey, Kristin; Sowers, MaryFran; Zheng, Huiyong; Jackson, Elizabeth A.

    2009-01-01

    We investigated whether subclinical inflammatory markers high-sensitivity C-reactive protein (CRP) and fibrinogen are related to measures of physical functioning in midlife women. Our sample included 543 participants in the Michigan site of Study of Women’s Health Across the Nation (SWAN). Predictors included CRP from serum and fibrinogen from plasma. Performance-based outcomes included measures of gait, hand grip strength, flexibility, stair climb, 40-foot walk, and chair rise. Perception of physical functioning was assessed with the Medical Outcomes Study Short-Form 36 questionnaire. Regression analyses adjusted for relevant covariates. Cross-sectional associations were identified between higher CRP and more time spent in double support (with both feet on the floor while walking), shorter forward reach, slower 2-lb lift, and slower stair climb. Higher CRP and fibrinogen were associated with worse perceived functioning in cross-sectional analyses. Predictive associations across time were found between higher CRP and increased time spent in double support, diminishing forward reach distance and grip strength and worse perceived physical functioning. Predictive associations across time were also found between higher fibrinogen and greater time spent in double support, slower stair climb and worse perceived physical functioning. Our results suggest that inflammatory processes are associated with poor physical functioning in midlife women. PMID:19819323

  6. Hollow-structured mesoporous materials: chemical synthesis, functionalization and applications.

    PubMed

    Li, Yongsheng; Shi, Jianlin

    2014-05-28

    Hollow-structured mesoporous materials (HMMs), as a kind of mesoporous material with unique morphology, have been of great interest in the past decade because of the subtle combination of the hollow architecture with the mesoporous nanostructure. Benefitting from the merits of low density, large void space, large specific surface area, and, especially, the good biocompatibility, HMMs present promising application prospects in various fields, such as adsorption and storage, confined catalysis when catalytically active species are incorporated in the core and/or shell, controlled drug release, targeted drug delivery, and simultaneous diagnosis and therapy of cancers when the surface and/or core of the HMMs are functionalized with functional ligands and/or nanoparticles, and so on. In this review, recent progress in the design, synthesis, functionalization, and applications of hollow mesoporous materials are discussed. Two main synthetic strategies, soft-templating and hard-templating routes, are broadly sorted and described in detail. Progress in the main application aspects of HMMs, such as adsorption and storage, catalysis, and biomedicine, are also discussed in detail in this article, in terms of the unique features of the combined large void space in the core and the mesoporous network in the shell. Functionalization of the core and pore/outer surfaces with functional organic groups and/or nanoparticles, and their performance, are summarized in this article. Finally, an outlook of their prospects and challenges in terms of their controlled synthesis and scaled application is presented. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Synthesis and structures of a pincer-type rhodium(iii) complex: reactivity toward biomolecules.

    PubMed

    Milutinović, Milan M; Bogojeski, Jovana V; Klisurić, Olivera; Scheurer, Andreas; Elmroth, Sofi K C; Bugarčić, Živadin D

    2016-10-04

    A novel rhodium(iii) complex [Rh(III)(H2L(tBu))Cl3] (1) (H2L(tBu) = 2,6-bis(5-tert-butyl-1H-pyrazol-3-yl)pyridine) containing a pincer type, tridentate nitrogen-donor chelate system was synthesized. Single crystal X-ray structure analysis revealed that 1 crystallizes in the orthorhombic space group Pbcn with a = 20.7982(6), b = 10.8952(4), c = 10.9832(4) Å, V = 2488.80(15) Å(3), and eight molecules in the unit cell. The rhodium center in the complex [Rh(III)(H2L(tBu))Cl3] (1) is coordinated in a slightly distorted octahedral geometry by the tridentate N,N,N-donor and three chloro ligands, adopting a mer arrangement with an essentially planar ligand skeleton. Due to the tridentate coordination of the N,N,N-donor, the central nitrogen atom N1 is located closer to the Rh(III) center. The reactivity of the synthesized complex toward small biomolecules (l-methionine (l-Met), guanosine-5'-monophosphate (5'-GMP), l-histidine (l-His) and glutathione (GSH)) and to a series of duplex DNAs and RNA was investigated. The order of reactivity of the studied small biomolecules is: 5'-GMP > GSH > l-Met > l-His. Duplex RNA reacts faster with the [Rh(III)(H2L(tBu))Cl3] complex than duplex DNA, while shorter duplex DNA (15mer GG) reacts faster compared with 22mer GG duplex DNA. In addition, a higher reactivity is achieved with a DNA duplex with a centrally located GG-sequence than with a 22GTG duplex DNA, in which the GG-sequence is separated by a T base. Furthermore, the interaction of this metal complex 1 with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) was examined by absorption (UV-Vis) and emission spectral studies (EthBr displacement studies). Overall, the studied complex exhibited good DNA and BSA interaction ability.

  8. Synthesis, Structure, and Reactivity of Arylchlorobis(dialkyl sulfide)platinum(II) Complexes.

    PubMed

    Wendt, Ola F.; Oskarsson Å, Åke; Leipoldt, Johann G.; Elding, Lars I.

    1997-09-24

    Complexes trans-[PtRCl(SR'(2))(2)], where R = Ph, mesityl, and p-anisyl and R' = Me or Et, have been synthesized and their crystal and molecular structures determined. Crystals of trans-[PtPhCl(SEt(2))(2)] (2) are triclinic (P&onemacr;) with a = 10.112(6) Å, b = 13.158(2) Å, c = 14.714(5) Å, alpha = 102.48(2) degrees, beta = 94.394(4) degrees, gamma = 90.22(3) degrees, and Z = 4. Crystals of trans-[Pt(mesityl)Cl(SMe(2))(2)] (4) are monoclinic (P2(1)/c) with a = 13.158(2) Å, b = 9.170(1) Å, c = 16.013(3) Å, beta = 120.93(2) degrees, and Z = 4, and crystals of [Pt(p-anisyl)Cl(SMe(2))(2)] (5) are monoclinic (P2(1)/n) with a = 9.879(4) Å, b = 8.128(2) Å, c = 19.460(5) Å, beta = 96.56(3) degrees, and Z = 4. All complexes are square-planar, featuring Pt-Cl distances between 2.40 and 2.42 Å, indicating a large ground-state trans influence of the aryl group. The coordination geometry is maintained in methanol and chloroform solution as shown by (1)H-NMR spectra. The kinetics of substitution of the labile chloride trans to aryl by various nucleophiles has been studied in methanol by variable-temperature and -pressure stopped-flow spectrophotometry. A two-term rate law with a well-developed solvolytic pathway is followed. Negative entropies and volumes of activation indicate an associative mode of activation in all cases, independent of steric blocking of the axial sites and a large Pt-Cl ground-state bond-weakening. Comparison of the reaction rates of the present series of complexes with their bis(phosphine) analogues and with related cyclometalated compounds shows that the triethylphosphine complexes are 2-3 orders of magnitude less reactive than the thioether complexes, which in turn are a factor 10-20 less reactive than the cyclometalated ones. This reactivity increase can be rationalized mainly in terms of a decrease in steric hindrance in the series. There seems to be no inherent differences with regard to trans labilizing ability of the aryl ligands in the

  9. Organic grape juice intake improves functional capillary density and postocclusive reactive hyperemia in triathletes

    PubMed Central

    Gonçalves, Mariana Correa; Bezerra, Flavia Fioruci; de Araujo Eleutherio, Elis Cristina; Bouskela, Eliete; Koury, Josely

    2011-01-01

    OBJECTIVE: The aim of this study was to evaluate the effect of organic grape juice intake on biochemical variables and microcirculatory parameters in triathlon athletes. INTRODUCTION: The physiological stress that is imposed by a strenuous sport, such as a triathlon, together with an insufficient amount of antioxidants in the diet may cause oxidative imbalance and endothelial dysfunction. METHODS: Ten adult male triathletes participated in this study. A venous blood sample was drawn before (baseline) and after 20 days of organic grape juice intake (300 ml/day). Serum insulin, plasma glucose and uric acid levels, the total content of polyphenols, and the erythrocyte superoxide dismutase activity were determined. The functional microcirculatory parameters (the functional capillary density, red blood cell velocity at baseline and peak levels, and time required to reach the peak red blood cell velocity during postocclusive reactive hyperemia after a one-min arterial occlusion) were evaluated using nailfold videocapillaroscopy. RESULTS: Compared with baseline levels, the peak levels of serum insulin (p = 0.02), plasma uric acid (p = 0.04), the functional capillary density (p = 0.003), and the red blood cell velocity (p<0.001) increased, whereas the plasma glucose level (p<0.001), erythrocyte superoxide dismutase activity (p = 0.04), and time required to reach red blood cell velocity during postocclusive reactive hyperemia (p = 0.04) decreased after organic grape juice intake. CONCLUSION: Our data showed that organic grape juice intake improved glucose homeostasis, antioxidant capacity, and microvascular function, which may be due to its high concentration of polyphenols. These results indicate that organic grape juice has a positive effect in endurance athletes. PMID:22179155

  10. Organic grape juice intake improves functional capillary density and postocclusive reactive hyperemia in triathletes.

    PubMed

    Gonçalves, Mariana Correa; Bezerra, Flavia Fioruci; Eleutherio, Elis Cristina de Araujo; Bouskela, Eliete; Koury, Josely

    2011-01-01

    The aim of this study was to evaluate the effect of organic grape juice intake on biochemical variables and microcirculatory parameters in triathlon athletes. The physiological stress that is imposed by a strenuous sport, such as a triathlon, together with an insufficient amount of antioxidants in the diet may cause oxidative imbalance and endothelial dysfunction. Ten adult male triathletes participated in this study. A venous blood sample was drawn before (baseline) and after 20 days of organic grape juice intake (300 ml/day). Serum insulin, plasma glucose and uric acid levels, the total content of polyphenols, and the erythrocyte superoxide dismutase activity were determined. The functional microcirculatory parameters (the functional capillary density, red blood cell velocity at baseline and peak levels, and time required to reach the peak red blood cell velocity during postocclusive reactive hyperemia after a one-min arterial occlusion) were evaluated using nailfold videocapillaroscopy. Compared with baseline levels, the peak levels of serum insulin ( p = 0.02), plasma uric acid ( p = 0.04), the functional capillary density ( p = 0.003), and the red blood cell velocity (p < 0.001) increased, whereas the plasma glucose level (p,0.001), erythrocyte superoxide dismutase activity ( p = 0.04), and time required to reach red blood cell velocity during postocclusive reactive hyperemia ( p = 0.04) decreased after organic grape juice intake. Our data showed that organic grape juice intake improved glucose homeostasis, antioxidant capacity, and microvascular function, which may be due to its high concentration of polyphenols. These results indicate that organic grape juice has a positive effect in endurance athletes.

  11. Synthesis and reactivity of aliphatic sulfur pentafluorides from substituted (pentafluorosulfanyl)benzenes.

    PubMed

    Vida, Norbert; Václavík, Jiří; Beier, Petr

    2016-01-01

    Oxidation of 3- and 4-pentafluorosulfanyl-substituted anisoles and phenols with hydrogen peroxide and sulfuric acid provided a mixture of SF5-substituted muconolactone, maleic, and succinic acids. A plausible mechanism for the formation of the aliphatic SF5 compounds was presented and their chemical reactivity was investigated. SF5-substituted para-benzoquinone was synthesized; its oxidation led to an improved yield of 2-(pentafluorosulfanyl)maleic acid. The reaction of SF5-substituted maleic anhydride and para-benzoquinone with cyclopentadiene afforded the Diels-Alder adducts. Decomposition of 3-(pentafluorosulfanyl)muconolactone in acidic, neutral and basic aqueous media was investigated and the decarboxylation of 2-(pentafluorosulfanyl)maleic acid provided 3-(pentafluorosulfanyl)acrylic acid.

  12. Reactive template synthesis of polypyrrole nanotubes for fabricating metal/conducting polymer nanocomposites.

    PubMed

    Zhang, Jun; Liu, Xianghong; Zhang, Lixue; Cao, Bingqiang; Wu, Shihua

    2013-03-25

    Unique nanocomposites of polypyrrole/Au and polypyrrole/Pt hybrid nanotubes are synthesized employing polypyrrole (PPy) nanotubes as an advanced support by solution reduction. The conducting polymer PPy nanotubes are fabricated by using pre-prepared MnO2 nanowires as the reactive templates. MnO2 nanowires induce the 1D polymerization of pyrrole monomers and the simultaneous dissolution of the templates affords the hollow tube-like structure. The loading content of metal nanoparticles in the nanocomposites could be adjusted by simply changing the amount of metal precursors. This work provides an efficient approach to fabricate an important kind of metal/conducting polymer hybrid nanotubes that are potentially useful for electrocatalyst and sensor materials. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Synthesis and reactivity of aliphatic sulfur pentafluorides from substituted (pentafluorosulfanyl)benzenes

    PubMed Central

    Vida, Norbert; Václavík, Jiří

    2016-01-01

    Summary Oxidation of 3- and 4-pentafluorosulfanyl-substituted anisoles and phenols with hydrogen peroxide and sulfuric acid provided a mixture of SF5-substituted muconolactone, maleic, and succinic acids. A plausible mechanism for the formation of the aliphatic SF5 compounds was presented and their chemical reactivity was investigated. SF5-substituted para-benzoquinone was synthesized; its oxidation led to an improved yield of 2-(pentafluorosulfanyl)maleic acid. The reaction of SF5-substituted maleic anhydride and para-benzoquinone with cyclopentadiene afforded the Diels–Alder adducts. Decomposition of 3-(pentafluorosulfanyl)muconolactone in acidic, neutral and basic aqueous media was investigated and the decarboxylation of 2-(pentafluorosulfanyl)maleic acid provided 3-(pentafluorosulfanyl)acrylic acid. PMID:26877813

  14. Synthesis and biological evaluation of lovastatin-derived aliphatic hydroxamates that induce reactive oxygen species.

    PubMed

    Lin, Ruo-Kai; Lin, Yuh-Feng; Hsu, Ming-Jen; Hsieh, Chang-Lin; Wang, Chen-Yu; Huang, Chih-Chiang; Huang, Wei-Jan

    2016-11-15

    Some hydroxamate compounds induce cancer cell death by intracellular reactive oxygen species (ROS). This study introduced the hydroxamate core into lovastatin, a fungus metabolite clinically used for the treatment of hypercholesterolemia. The resulting compounds were evaluated for the activity for inducing ROS production. Most compounds exhibited higher activity than original lovastatin. Of these compounds, compound 3c had the most potent activity. Test of cytotoxicity in a panel of human cancer cell lines indicated compound 3c had activities superior to cisplatin in prostate cancer PC-3 cells and breast cancer T47D cells. In contrast, it in amounts up to 40μM had a much lower cytotoxic effect on normal human IMR-90 cells. Further profiling of cell cycle progression, cell apoptosis, and DNA damage activated checkpoint signaling pathway revealed the important role of compound 3c-mediated cytotoxicity in ROS generation. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Two-coordinate terminal zinc hydride complexes: synthesis, structure and preliminary reactivity studies.

    PubMed

    Dawkins, Michael J C; Middleton, Ewart; Kefalidis, Christos E; Dange, Deepak; Juckel, Martin M; Maron, Laurent; Jones, Cameron

    2016-08-18

    The first examples of essentially two-coordinate, monomeric zinc hydride complexes, LZnH (L = -N(Ar)(SiR3)) (Ar = C6H2{C(H)Ph2}2R'-2,6,4; R = Me, R' = Pr(i) (L'); R = Pr(i), R' = Me (L*); R = Pr(i), R' = Pr(i) (L(†))) have been prepared and shown by crystallographic studies to have near linear N-Zn-H fragments. The results of computational studies imply that any PhZn interactions in the compounds are weak at best. Preliminary reactivity studies reveal the compounds to be effective for the stoichiometric hydrozincation and catalytic hydrosilylation of carbonyl compounds.

  16. Direct synthesis of stereodefined and functionalized dienes as valuable building blocks.

    PubMed

    Maulide, Nuno; Souris, Caroline; Frébault, Frédéric; Luparia, Marco; Audisio, Davide

    2014-01-01

    We have reported a direct and stereoselective synthesis of functionalized dienoic carboxylates from the simple bicyclic lactone 1. The use of oxygen- or nitrogen-based nucleophiles in a domino allylic alkylation/4π-electrocyclic ring opening affords reliable access to dienes with interesting functionalities. Alternatively, halide substitution offers synthesis of other classes of functionalized dienoic acids. Herein, we demonstrate the utility of such dienoic products as key building blocks in various transformations as well as natural product synthesis.

  17. Synthesis, conformational, spectroscopic and chemical reactivity analysis of 2-cyano-3-(1H-pyrrol-2-yl)acrylohydrazide using experimental and quantum chemical approaches

    NASA Astrophysics Data System (ADS)

    Rawat, Poonam; Singh, R. N.

    2015-02-01

    This paper describes the synthesis, spectroscopic (1H and 13C NMR, UV-Visible, FT-IR and ESI Mass), conformational analysis, chemical reactivity and non-linear optical (NLO) properties of newly synthesized pyrrole derivative 2-cyano-3-(1H-pyrrol-2-yl)acrylohydrazide (2CPA) C8H8N4O using experimental and quantum chemical techniques. The presence of signal at δ 8.010 ppm due to vinyl proton as well as NH and NH2 protons signals at 11.054 and 2.499 ppm in experimental 1H NMR spectrum indicate that 2CPA contain sbnd CHdbnd CCNsbnd and sbnd NHsbnd NH2 frame. The combined experimental and theoretical symmetric (3194 cm-1) and asymmetric (3221 cm-1) stretching wavenumber analysis confirms free NH2 group in the solid phase FT-IR spectrum of the synthesized compound. The interaction energies of dimer formation using density functional theory (DFT) and Quantum theory of Atoms in Molecules (QTAIM) calculations are found to be 20.210, 19.683 kcal/mol, respectively. The maximum values of the electrophilic reactivity descriptors at C6 indicate that this site is more prone to nucleophilic attack and favoring the formation of heterocyclic derivatives. A natural bond orbital (NBOs) analysis has been carried out to investigate intramolecular charge transfer, conjugative and hyperconjugative interactions within molecule. The calculated first hyperpolarizability (β0) of 2CPA, indicates that investigated molecule will show non-linear optical response and might be used as non-linear optical (NLO) material.

  18. Density functional reactivity theory study of SN2 reactions from the information-theoretic perspective.

    PubMed

    Wu, Zemin; Rong, Chunying; Lu, Tian; Ayers, Paul W; Liu, Shubin

    2015-10-28

    As a continuation of our recent efforts to quantify chemical reactivity with quantities from the information-theoretic approach within the framework of density functional reactivity theory, the effectiveness of applying these quantities to quantify electrophilicity for the bimolecular nucleophilic substitution (SN2) reactions in both gas phase and aqueous solvent is presented in this work. We examined a total of 21 self-exchange SN2 reactions for the compound with the general chemical formula of R1R2R3C-F, where R1, R2, and R3 represent substituting alkyl groups such as -H, -CH3, -C2H5, -C3H7, and -C4H9 in both gas and solvent phases. Our findings confirm that scaling properties for information-theoretic quantities found elsewhere are still valid. It has also been verified that the barrier height has the strongest correlation with the electrostatic interaction, but the contributions from the exchange-correlation and steric effects, though less significant, are indispensable. We additionally unveiled that the barrier height of these SN2 reactions can reliably be predicted not only by the Hirshfeld charge and information gain at the regioselective carbon atom, as previously reported by us for other systems, but also by other information-theoretic descriptors such as Shannon entropy, Fisher information, and Ghosh-Berkowitz-Parr entropy on the same atom. These new findings provide further insights for the better understanding of the factors impacting the chemical reactivity of this vastly important category of chemical transformations.

  19. Chemical and Chemoenzymatic Synthesis of Glycoproteins for Deciphering Functions

    PubMed Central

    Wang, Lai-Xi; Amin, Mohammed N.

    2014-01-01

    Summary Glycoproteins are an important class of biomolecules involved in a number of biological recognition processes. However, natural and recombinant glycoproteins are usually produced as mixtures of glycoforms that differ in the structures of the pendent glycans, which are difficult to separate in pure glycoforms. As a result, synthetic homogeneous glycopeptides and glycoproteins have become indispensable probes for detailed structural and functional studies. A number of elegant chemical and biological strategies have been developed for synthetic construction of tailor-made, full-size glycoproteins to address specific biological problems. In this review, we highlight recent advances in chemical and chemoenzymatic synthesis of homogeneous glycoproteins. Selected examples are given to demonstrate the applications of tailor-made, glycan-defined glycoproteins for deciphering glycosylation functions. PMID:24439206

  20. Selective catalytic synthesis of functional allenes, cyclopentenones and oxolenes

    SciTech Connect

    Darcel, C.; Bruneau, C.; Dixneuf, P.H.

    1995-12-31

    The most powerful method to produce allene derivatives consists in the selective activation of prop-2-yn-1-carbonates by a Pd(0) catalyst, via allenyl palladium(II) intermediate. This strategy has been used for the selective catalytic synthesis of derivatives. The alkynyl cyclic carbonates have the advantage to be readily prepared directly from CO{sub 2} and contain both propargylic and homopropargylic functionalities. Their activation, under mild conditions, by palladium(0) catalysts, associated with the suitable phosphine ligand, can be oriented to selectively prepare either alkynyl {alpha}-hydroxy allenes, 5-hydroxy alka-2,3-dienoates, functional cyclopentenones or oxolenes via cross coupling, mono-carbonylation, dicarbonylation and Heck-Type reactions respectively.

  1. Framed carbon nanostructures: synthesis and applications in functional SPM tips.

    PubMed

    Mukhin, I S; Fadeev, I V; Zhukov, M V; Dubrovskii, V G; Golubok, A O

    2015-01-01

    We present a synthesis method to fabricate framed carbon-based nanostructures having highly anisotropic shapes, in particular, the nanofork and nanoscalpel structures which are obtained systematically under optimized growth conditions. A theoretical model is developed to explain the formation of such nanostructures on Si cantilevers and W etched wires exposed to a focused electron beam. We then demonstrate the potentials of these nanostructures as functional tips for scanning probe microscopy. Owing to their anisotropic shapes, such tips can be very useful for nanolithography, nanosurgery of biological objects, and precise manipulation with surface particles. Overall, our method provides a simple and robust way to produce functional scanning probe microscopy tips with variable shapes and enhanced capabilities for different applications compared to standard cantilevers.

  2. Sleep quality and emotional reactivity cluster in bipolar disorders and impact on functioning.

    PubMed

    Etain, B; Godin, O; Boudebesse, C; Aubin, V; Azorin, J M; Bellivier, F; Bougerol, T; Courtet, P; Gard, S; Kahn, J P; Passerieux, C; Leboyer, M; Henry, C

    2017-07-16

    Bipolar disorders (BD) are characterized by sleep disturbances and emotional dysregulation both during acute episodes and remission periods. We hypothesized that sleep quality (SQ) and emotional reactivity (ER) defined clusters of patients with no or abnormal SQ and ER and we studied the association with functioning. We performed a bi-dimensional cluster analysis using SQ and ER measures in a sample of 533 outpatients patients with BD (in remission or with subsyndromal mood symptoms). Clusters were compared for mood symptoms, sleep profile and functioning. We identified three clusters of patients: C1 (normal ER and SQ, 54%), C2 (hypo-ER and low SQ, 22%) and C3 (hyper-ER and low SQ, 24%). C1 was characterized by minimal mood symptoms, better sleep profile and higher functioning than other clusters. Although highly different for ER, C2 and C3 had similar levels of subsyndromal mood symptoms as assessed using classical mood scales. When exploring sleep domains, C2 showed poor sleep efficiency and a trend for longer sleep latency as compared to C3. Interestingly, alterations in functioning were similar in C2 and C3, with no difference in any of the sub-domains. Abnormalities in ER and SQ delineated three clusters of patients with BD and significantly impacted on functioning. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  3. Cardiorespiratory fitness, pulmonary function and C-reactive protein levels in nonsmoking individuals with diabetes

    PubMed Central

    Francisco, C.O.; Catai, A.M.; Moura-Tonello, S.C.G.; Lopes, S.L.B.; Benze, B.G.; Del Vale, A.M.; Leal, A.M.O.

    2014-01-01

    The objective of this study was to evaluate cardiorespiratory fitness and pulmonary function and the relationship with metabolic variables and C-reactive protein (CRP) plasma levels in individuals with diabetes mellitus (DM). Nineteen men with diabetes and 19 age- and gender-matched control subjects were studied. All individuals were given incremental cardiopulmonary exercise and pulmonary function tests. In the exercise test, maximal workload (158.3±22.3 vs 135.1±25.2, P=0.005), peak heart rate (HRpeak: 149±12 vs 139±10, P=0.009), peak oxygen uptake (VO2peak: 24.2±3.2 vs 18.9±2.8, P<0.001), and anaerobic threshold (VO2VT: 14.1±3.4 vs 12.2±2.2, P=0.04) were significantly lower in individuals with diabetes than in control subjects. Pulmonary function test parameters, blood pressure, lipid profile (triglycerides, HDL, LDL, and total cholesterol), and CRP plasma levels were not different in control subjects and individuals with DM. No correlations were observed between hemoglobin A1C (HbA1c), CRP and pulmonary function test and cardiopulmonary exercise test performance. In conclusion, the results demonstrate that nonsmoking individuals with DM have decreased cardiorespiratory fitness that is not correlated with resting pulmonary function parameters, HbA1c, and CRP plasma levels. PMID:24760118

  4. Cardiorespiratory fitness, pulmonary function and C-reactive protein levels in nonsmoking individuals with diabetes.

    PubMed

    Francisco, C O; Catai, A M; Moura-Tonello, S C G; Lopes, S L B; Benze, B G; Del Vale, A M; Leal, A M O

    2014-05-01

    The objective of this study was to evaluate cardiorespiratory fitness and pulmonary function and the relationship with metabolic variables and C-reactive protein (CRP) plasma levels in individuals with diabetes mellitus (DM). Nineteen men with diabetes and 19 age- and gender-matched control subjects were studied. All individuals were given incremental cardiopulmonary exercise and pulmonary function tests. In the exercise test, maximal workload (158.3 ± 22.3 vs 135.1 ± 25.2, P=0.005), peak heart rate (HRpeak: 149 ± 12 vs 139 ± 10, P=0.009), peak oxygen uptake (VO2peak: 24.2 ± 3.2 vs 18.9 ± 2.8, P<0.001), and anaerobic threshold (VO2VT: 14.1 ± 3.4 vs 12.2 ± 2.2, P=0.04) were significantly lower in individuals with diabetes than in control subjects. Pulmonary function test parameters, blood pressure, lipid profile (triglycerides, HDL, LDL, and total cholesterol), and CRP plasma levels were not different in control subjects and individuals with DM. No correlations were observed between hemoglobin A1C (HbA1c), CRP and pulmonary function test and cardiopulmonary exercise test performance. In conclusion, the results demonstrate that nonsmoking individuals with DM have decreased cardiorespiratory fitness that is not correlated with resting pulmonary function parameters, HbA1c, and CRP plasma levels.

  5. Synthesis of mixed Cp/Tp(Me2) lanthanide complexes from lanthanocene precursors and their structures and reactivities.

    PubMed

    Han, Fuyan; Zhang, Jie; Han, Yanan; Zhang, Zhengxing; Chen, Zhenxia; Weng, Linhong; Zhou, Xigeng

    2009-02-16

    Reaction of Cp(2)LnCl with 1 equiv of KTp(Me2) in toluene gives the mixed Tp(Me2)/Cp lanthanide complexes Cp(2)Ln(Tp(Me2)) (Ln = Yb (1a), Er (1b), Dy (1c)), while unexpected complexes CpLn(Tp(Me2))Cl(THF) (Ln = Yb (2a), Er (2b.THF), Dy (2c), Y (2d)) are obtained when the reactions are carried out in THF. Complex 2b can also be formed by the reaction of CpErCl(2)(THF)(3) with 1 equiv of KTp(Me2) in THF. Moreover, complex 1a can also be obtained from the reaction of Cp(3)Yb and KTp(Me2). The results not only represent an efficient and versatile method for the synthesis of mixed Cp/Tp(Me2) lanthanide complexes but also provide new insight into the reactivity of Cp(2)LnCl. Furthermore, the reactivities of complexes 1a-c toward proton-donating reagents are examined. It has been found that 1b reacts with benzotriazole (C(6)H(4)NHN(2)) in THF to yield a lanthanide metallomacrocyclic complex [(Tp(Me2))CpEr(mu-N(3)C(6)H(4))](3) (3), while the reaction of 1a with 1 equiv of 2-aminopyridine in THF gives an unexpected oxide complex [(Tp(Me2))Yb(2-HNC(5)H(4)N)](2)(mu-O) (4). Presumably, the oxide ligand of compound 4 results from adventitious water. In addition, treatment of 1c with 2 equiv of 3,5-dimethylpyrazole yields a completely Cp-abstracted product (Tp(Me2))Dy(Pz(Me2))(2)(THF) (5), which can also be directly obtained from a three-component reaction of Cp(2)DyCl, KTp(Me2), and 3,5-dimethylpyrazole in THF. These results further indicate that the new mixed Tp(Me2)/Cp lanthanide complexes are practical and versatile precursors for the synthesis of poly(pyrazolyl)borate lanthanide derivatives. All new compounds have been characterized by elemental analysis and spectroscopic methods. The structures of complexes 1a,b and 2-5 have also been determined through single-crystal X-ray diffraction analysis.

  6. Proposal of a simple and effective local reactivity descriptor through a topological analysis of an orbital-weighted fukui function.

    PubMed

    Pino-Rios, Ricardo; Yañez, Osvaldo; Inostroza, Diego; Ruiz, Lina; Cardenas, Carlos; Fuentealba, Patricio; Tiznado, William

    2017-03-30

    The prediction of reactivity is one of the long-standing objectives of chemistry, contributing to enforce the link between theory and experiment. In particular, the regioselectivity of aromatic molecules has motivated the proposal of different reactivity descriptors based on foundational theories, like Frontier Molecular Orbital (FMO) theory and density functional theory, to predict and rationalize such regioselectivity. This article examines cases where reactivity descriptors, based on FMO theories, are known to have failed, specifically on electrophilic aromatic substitution reactions, through a simple but effective new reactivity model: the Orbital-weighted Fukui function ( fw-(r)) and its topological analysis. Interestingly, this descriptor proves to be effective in adequately predicting regioselectivities where other approximations failed. © 2017 Wiley Periodicals, Inc.

  7. Synthesis of water-soluble CdSe quantum dots with various fluorescent properties and their application in immunoassay for determination of C-reactive protein.

    PubMed

    Gasparyan, V K

    2014-09-01

    Effects of various factors on synthesis and fluorescent properties of CdSe quantum dots were studied. It was shown that variation of pH, stabilizer and concentration of precursors brings to obtaining of quantum dots with various fluorescent properties. The nanoparticles prepared were conjugated with rabbit antibodies to C-Reactive protein and C-Reactive protein for competitive immunoassay for determination of CRP. It was shown that interaction of these dots as a result of antigen-antibody reaction brings to resonance energy transfer and these changes in fluorescence spectra correlate with concentration of CRP. This approach permits to determine CRP in range between 4-100 ng.

  8. Revisiting the chemical reactivity indices as the state function derivatives. The role of classical chemical hardness

    NASA Astrophysics Data System (ADS)

    Malek, Ali; Balawender, Robert

    2015-02-01

    The chemical reactivity indices as the equilibrium state-function derivatives are revisited. They are obtained in terms of the central moments (fluctuation formulas). To analyze the role of the chemical hardness introduced by Pearson [J. Am. Chem. Soc. 105, 7512 (1983)], the relations between the derivatives up to the third-order and the central moments are obtained. As shown, the chemical hardness and the chemical potential are really the principal indices of the chemical reactivity theory. It is clear from the results presented here that the chemical hardness is not the derivative of the Mulliken chemical potential (this means also not the second derivative of the energy at zero-temperature limit). The conventional quadratic dependence of energy, observed at finite temperature, reduces to linear dependence on the electron number at zero-temperature limit. The chemical hardness plays a double role in the admixture of ionic states to the reference neutral state energy: it determines the amplitude of the admixture and regulates the damping of its thermal factor.

  9. Revisiting the chemical reactivity indices as the state function derivatives. The role of classical chemical hardness

    SciTech Connect

    Malek, Ali; Balawender, Robert

    2015-02-07

    The chemical reactivity indices as the equilibrium state-function derivatives are revisited. They are obtained in terms of the central moments (fluctuation formulas). To analyze the role of the chemical hardness introduced by Pearson [J. Am. Chem. Soc. 105, 7512 (1983)], the relations between the derivatives up to the third-order and the central moments are obtained. As shown, the chemical hardness and the chemical potential are really the principal indices of the chemical reactivity theory. It is clear from the results presented here that the chemical hardness is not the derivative of the Mulliken chemical potential (this means also not the second derivative of the energy at zero-temperature limit). The conventional quadratic dependence of energy, observed at finite temperature, reduces to linear dependence on the electron number at zero-temperature limit. The chemical hardness plays a double role in the admixture of ionic states to the reference neutral state energy: it determines the amplitude of the admixture and regulates the damping of its thermal factor.

  10. Revisiting the chemical reactivity indices as the state function derivatives. The role of classical chemical hardness.

    PubMed

    Malek, Ali; Balawender, Robert

    2015-02-07

    The chemical reactivity indices as the equilibrium state-function derivatives are revisited. They are obtained in terms of the central moments (fluctuation formulas). To analyze the role of the chemical hardness introduced by Pearson [J. Am. Chem. Soc. 105, 7512 (1983)], the relations between the derivatives up to the third-order and the central moments are obtained. As shown, the chemical hardness and the chemical potential are really the principal indices of the chemical reactivity theory. It is clear from the results presented here that the chemical hardness is not the derivative of the Mulliken chemical potential (this means also not the second derivative of the energy at zero-temperature limit). The conventional quadratic dependence of energy, observed at finite temperature, reduces to linear dependence on the electron number at zero-temperature limit. The chemical hardness plays a double role in the admixture of ionic states to the reference neutral state energy: it determines the amplitude of the admixture and regulates the damping of its thermal factor.

  11. Modulating the reactivity of Ni-containing Pt(111)-skin catalysts by density functional theory calculations

    NASA Astrophysics Data System (ADS)

    Su, Hai-Yan; Bao, Xin-He; Li, Wei-Xue

    2008-05-01

    We present here a first principles density functional theory investigation of the reactivity of Pt(111)-skin catalysts, which are varied from surface alloys with Ni to bulk PtxNi1-x (x=0.25,0.50,0.75) alloys. Molecule (CO, O, and H) adsorption and oxidation of CO +O and H +O reactions were studied and analyzed in detail. Independent of the adsorbates, the interaction between adsorbates and substrates becomes weakened with increase in Ni, due to the downshift of d-band center of surface Pt atoms. Moreover, activation barriers of CO and H oxidation toward atomic oxygen gradually decrease. In term of CO preferential oxidation (PROX) in excess of hydrogen, it turns out that the overall reactivity and selectivity rely on the optimum of various elementary steps involved such as competitive molecular (dissociative) adsorption and oxidation reaction. The present calculations show that Pt3Ni(111) with Pt overlayer is an optimum catalyst for CO PROX in excess of hydrogen.

  12. Modulating the reactivity of Ni-containing Pt(111)-skin catalysts by density functional theory calculations.

    PubMed

    Su, Hai-Yan; Bao, Xin-He; Li, Wei-Xue

    2008-05-21

    We present here a first principles density functional theory investigation of the reactivity of Pt(111)-skin catalysts, which are varied from surface alloys with Ni to bulk PtxNi 1-x (x=0.25,0.50,0.75) alloys. Molecule (CO, O, and H) adsorption and oxidation of CO+O and H+O reactions were studied and analyzed in detail. Independent of the adsorbates, the interaction between adsorbates and substrates becomes weakened with increase in Ni, due to the downshift of d-band center of surface Pt atoms. Moreover, activation barriers of CO and H oxidation toward atomic oxygen gradually decrease. In term of CO preferential oxidation (PROX) in excess of hydrogen, it turns out that the overall reactivity and selectivity rely on the optimum of various elementary steps involved such as competitive molecular (dissociative) adsorption and oxidation reaction. The present calculations show that Pt3Ni(111) with Pt overlayer is an optimum catalyst for CO PROX in excess of hydrogen.

  13. Reading as functional coordination: not recycling but a novel synthesis

    PubMed Central

    Lachmann, Thomas; van Leeuwen, Cees

    2014-01-01

    The Functional Coordination approach describes the processes involved in learning to read as a form of procedural learning in which pre-existing skills, mainly from the visual, and auditory domain, are (1) recruited, (2) modified, and (3) coordinated to create the procedures for reading text, which form the basis of subsequent (4) automatization. In this context, we discuss evidence relating to the emerging prevalence of analytic processing in letter perception. We argue that the process of learning to read does not have to lead to a loss of perceptual skill as consequence of a “cultural recycling”; learning to read just leads to a novel synthesis of functions, which are coordinated for reading and then automatized as a package over several years. Developmental dyslexia is explained within this framework as a Functional Coordination Deficit (Lachmann, 2002), since the coordination level is assumed to be most liable to manifest deficiencies. This is because, at this level, the greatest degree of fine tuning of complex functions is required. Thus, developmental dyslexia is not seen as a consequence of a deficient automatization per se, but of automatization of abnormally developed functional coordination. PMID:25309489

  14. Amine-Reactive Azlactone-Containing Nanofibers for the Immobilization and Patterning of New Functionality on Nanofiber-Based Scaffolds.

    PubMed

    Kratochvil, Michael J; Carter, Matthew C D; Lynn, David M

    2017-03-22

    We report the design of amine-reactive polymer nanofibers and nonwoven reactive nanofiber mats fabricated by the electrospinning of azlactone-functionalized polymers. We demonstrate that randomly oriented nanofibers fabricated using a random copolymer of methyl methacrylate and 2-vinyl-4,4-dimethylazlactone contain intact and reactive azlactone groups that can be used to introduce new chemical functionality and modulate important interfacial properties of these materials (e.g., wetting behaviors) by postfabrication treatment with primary amine-based nucleophiles. The facile and "click-like" nature of these reactions permits functionalization under mild conditions without substantial changes to nanofiber or mat morphologies. This approach also enables the patterning of new functionality on mat-coated surfaces by treatment with bulk solutions of primary amines or by using methods such as microcontact printing. Further, these reactive mats can also, themselves, be contact-transferred or "printed" onto secondary surfaces by pressing them into contact with other amine-functionalized objects. Finally, we demonstrate that functionalization with hydrophobic amines can increase the stability of these materials in aqueous environments and yield hydrophobic nanofiber scaffolds useful for the design of "slippery" liquid-infused materials. The approaches reported here enable the introduction of new properties to reactive polymer mats after fabrication and, thus, reduce the need to synthesize individual functional polymers prior to electrospinning to achieve new properties. The azlactone chemistry used here broadens the scope of reactions that can be used to functionalize polymer nanofibers and is likely to prove general. We anticipate that this approach can be used with a range of amines or other nucleophiles (e.g., alcohols or thiols) to design nanofibers and reactive nanofiber-based materials with new physical properties, surface features, and behaviors that may be difficult

  15. The synthesis, characterization and reactivity of high oxidation state nickel fluorides

    SciTech Connect

    Chacon, L.C. |

    1997-12-01

    The research described in this thesis has mainly addressed the challenge of the synthesis of thermodynamically unstable nickel fluorides, which cannot be made by traditional thermal methods. A low-temperature approach towards the synthesis of such transition metal fluorides exploits the greater thermodynamic stability of high oxidation states in anions and involves the use of anhydrous hydrogen fluoride (aHF) as a solvent. The general method consists of combining an aHF soluble starting material (e.g., K{sub 2}NiF{sub 6}) with a Lewis fluoroacid (e.g., BF{sub 3}), which precipitates a neutral polymeric solid state fluoride: 2 K{sup +} + NiF{sub 6}{sup 2{minus}} + BF{sub 3} {r_arrow} NiF{sub 4} + 2 BF{sub 4}{sup {minus}} + 2 K{sup +}. At room temperature, this reaction yields a different structural phase, with composition K{sub x}NiF{sub 3} (x {approx} 0.18). This material has a pseudo-hexagonal tungsten bronze structure (H{sub 0}-K{sub x}NiF{sub 3}), and is an ionic conductor, probably due to K{sup +} ions hosted in the lattice channels. R-NiF{sub 3} is capable of fluorinating a wide range of inorganic and organic substrates. These reactions have probably shed light on the mechanism of the Simons Electrochemical Fluorination (ECF) Process, an important industrial method of fluorinating organic compounds. It has long been speculated that NiF{sub 3} plays a role in the ECF process, which uses nickel electrodes in aHF solvent. K{sub 2}NiF{sub 6} also fluorinates organic compounds in aHF, but interestingly, yields different fluorinated products. The reduction of R-NiF{sub 3} and K{sub 2}NiF{sub 6} during fluorination reactions yields NiF{sub 2}. A method has been developed to regenerate NiF{sub 6}{sup 2{minus}} from NiF{sub 2}.

  16. Cued Reactivation of Motor Learning during Sleep Leads to Overnight Changes in Functional Brain Activity and Connectivity.

    PubMed

    Cousins, James N; El-Deredy, Wael; Parkes, Laura M; Hennies, Nora; Lewis, Penelope A

    2016-05-01

    Sleep plays a role in memory consolidation. This is demonstrated by improved performance and neural plasticity underlying that improvement after sleep. Targeted memory reactivation (TMR) allows the manipulation of sleep-dependent consolidation through intentionally biasing the replay of specific memories in sleep, but the underlying neural basis of these altered memories remains unclear. We use functional magnetic resonance imaging (fMRI) to show a change in the neural representation of a motor memory after targeted reactivation in slow-wave sleep (SWS). Participants learned two serial reaction time task (SRTT) sequences associated with different auditory tones (high or low pitch). During subsequent SWS, one sequence was reactivated by replaying the associated tones. Participants were retested on both sequences the following day during fMRI. As predicted, they showed faster reaction times for the cued sequence after targeted memory reactivation. Furthermore, increased activity in bilateral caudate nucleus and hippocampus for the cued relative to uncued sequence was associated with time in SWS, while increased cerebellar and cortical motor activity was related to time in rapid eye movement (REM) sleep. Functional connectivity between the caudate nucleus and hippocampus was also increased after targeted memory reactivation. These findings suggest that the offline performance gains associated with memory reactivation are supported by altered functional activity in key cognitive and motor networks, and that this consolidation is differentially mediated by both REM sleep and SWS.

  17. Synthesis, Characterization and Reactivity of Nanostructured Zero-Valent Iron Particles for Degradation of Azo Dyes

    NASA Astrophysics Data System (ADS)

    Mikhailov, Ivan; Levina, Vera; Leybo, Denis; Masov, Vsevolod; Tagirov, Marat; Kuznetsov, Denis

    Nanostructured zero-valent iron (NSZVI) particles were synthesized by the method of ferric ion reduction with sodium borohydride with subsequent drying and passivation at room temperature in technical grade nitrogen. The obtained sample was characterized by means of X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and dynamic light scattering studies. The prepared NSZVI particles represent 100-200nm aggregates, which consist of 20-30nm iron nanoparticles in zero-valent oxidation state covered by thin oxide shell. The reactivity of the NSZVI sample, as the removal efficiency of refractory azo dyes, was investigated in this study. Two azo dye compounds, namely, orange G and methyl orange, are commonly detected in waste water of textile production. Experimental variables such as NSZVI dosage, initial dye concentration and solution pH were investigated. The kinetic rates of degradation of both dyes by NSZVI increased with the decrease of solution pH from 10 to 3 and with the increase of NSZVI dosage, but decreased with the increase of initial dye concentration. The removal efficiencies achieved for both orange G and methyl orange were higher than 90% after 80min of treatment.

  18. Synthesis of 'reactive' and covalent polymeric multilayer coatings with durable superoleophobic and superoleophilic properties under water.

    PubMed

    Parbat, Dibyangana; Manna, Uttam

    2017-09-01

    Bioinspired underwater super-oil-wettability (superoleophilic/superoleophobic) properties are emerging as a potential avenue for developing smart materials for addressing issues related to healthcare, environment, energy, etc. However, the inherent poor durability of the materials that are mostly developed using polymeric hydrogel, metal oxide coatings and electrostatic multilayers often challenges the application of these wettability properties in practical scenarios. Here, 'amine-reactive' polymeric multilayers of nano-complex were developed to fabricate 'internal' underwater superoleophobic/superoleophilic coatings with impeccable physical/chemical durability. This allows the super-wetting properties to exist beyond the surface of the material and remain intact even after severe physical damage including erosion of the material and continuous exposure to an artificial-marine environment for more than 80 days. Moreover, this current design allowed for independent revalidation of some key hypotheses with direct experimental demonstrations, and provided a basis to develop highly durable super-oil-wettability properties under water. It is believed that this contemporary study will make a worthwhile contribution on developing multifunctional materials for widespread practical applications by exploiting these super-oil-wetting properties.

  19. Synthesis and characterization of InN nanocrystals on glass substrate by plasma assisted reactive evaporation

    NASA Astrophysics Data System (ADS)

    Ganesh, V.; Alizadeh, M.; Shuhaimi, A.; Sundaram, S.; Hakim, K. M.; Goh, B. T.; Rahman, S. A.

    2017-07-01

    InN nanocrystals were grown on glass substrate by plasma assisted reactive evaporation technique and the quality was compared with InN on Si (111) substrate. Single phase InN was confirmed by X-ray diffraction and micro Raman analysis on both the substrates. Agglomerated and Hexagonal faceting nanocrystals observed by field emission scanning electron microscopy. Energy dispersive X-ray analysis shows InN nanocrystals are nearly stochiometric. Photoluminescence reveals a broad emission near bandedge at 2 .04 eV and defect band at 1.07 eV. The Hall measurement on both the substrates reveals high electron carrier concentration. These encouraging results obtained suggested that high quality single crystalline InN can be obtained on glass substrate further optimizing the growth parameters. This novel growth of InN nanocrystals on glass substrate is an important step towards the development of monolithic, high efficiency low-cost InGaN-based renewable energy sources.

  20. Synthesis and reactivity of a mononuclear non-haem cobalt(IV)-oxo complex

    NASA Astrophysics Data System (ADS)

    Wang, Bin; Lee, Yong-Min; Tcho, Woon-Young; Tussupbayev, Samat; Kim, Seoung-Tae; Kim, Yujeong; Seo, Mi Sook; Cho, Kyung-Bin; Dede, Yavuz; Keegan, Brenna C.; Ogura, Takashi; Kim, Sun Hee; Ohta, Takehiro; Baik, Mu-Hyun; Ray, Kallol; Shearer, Jason; Nam, Wonwoo

    2017-03-01

    Terminal cobalt(IV)-oxo (CoIV-O) species have been implicated as key intermediates in various cobalt-mediated oxidation reactions. Herein we report the photocatalytic generation of a mononuclear non-haem [(13-TMC)CoIV(O)]2+ (2) by irradiating [CoII(13-TMC)(CF3SO3)]+ (1) in the presence of [RuII(bpy)3]2+, Na2S2O8, and water as an oxygen source. The intermediate 2 was also obtained by reacting 1 with an artificial oxidant (that is, iodosylbenzene) and characterized by various spectroscopic techniques. In particular, the resonance Raman spectrum of 2 reveals a diatomic Co-O vibration band at 770 cm-1, which provides the conclusive evidence for the presence of a terminal Co-O bond. In reactivity studies, 2 was shown to be a competent oxidant in an intermetal oxygen atom transfer, C-H bond activation and olefin epoxidation reactions. The present results lend strong credence to the intermediacy of CoIV-O species in cobalt-catalysed oxidation of organic substrates as well as in the catalytic oxidation of water that evolves molecular oxygen.

  1. Synthesis, characterization and reactivity of an imidazolin-2-iminato aluminium dihydride.

    PubMed

    Franz, Daniel; Irran, Elisabeth; Inoue, Shigeyoshi

    2014-03-21

    The reaction of bis(2,6-diisopropylphenyl)imidazolin-2-imine (LH, 1) with Me3N·AlH3 furnishes {μ-LAlH2}2 (2). The marked tendency of 2 to release its hydride substituents is ascribed to the strong electron-donor character of the imidazolin-2-iminato ligand. This is supported by its reactivity study and DFT calculations. In fact, compound 2 was further converted with Me3SiOTf, Me2S·BH3, Me2S·BBr3, and BX3 (with X = Cl, Br, and I) into {μ-LAl(H)OTf}2 (3), {μ-LAl(BH4)2}2 (4), and {μ-LAlX2}2 (5, X = Br; 6, X = Cl; 7, X = I), respectively. For all new aluminium complexes the formulation as dimers was evidenced by high resolution mass spectrometry, as well as single-crystal X-ray diffraction analysis. A prominent structural motif of these compounds is the square-planar four-membered Al2N2 ring with two bridging bulky imidazolin-2-imino moieties.

  2. Synthesis, Structure, and Reactivity of Anionic sp(2) -sp(3) Diboron Compounds: Readily Accessible Boryl Nucleophiles.

    PubMed

    Pietsch, Sabrina; Neeve, Emily C; Apperley, David C; Bertermann, Rüdiger; Mo, Fanyang; Qiu, Di; Cheung, Man Sing; Dang, Li; Wang, Jianbo; Radius, Udo; Lin, Zhenyang; Kleeberg, Christian; Marder, Todd B

    2015-05-04

    Lewis base adducts of tetra-alkoxy diboron compounds, in particular bis(pinacolato)diboron (B2 pin2 ), have been proposed as the active source of nucleophilic boryl species in metal-free borylation reactions. We report the isolation and detailed structural characterization (by solid-state and solution NMR spectroscopy and X-ray crystallography) of a series of anionic adducts of B2 pin2 with hard Lewis bases, such as alkoxides and fluoride. The study was extended to alternative Lewis bases, such as acetate, and other diboron reagents. The B(sp(2) )-B(sp(3) ) adducts exhibit two distinct boron environments in the solid-state and solution NMR spectra, except for [(4-tBuC6 H4 O)B2 pin2 ](-) , which shows rapid site exchange in solution. DFT calculations were performed to analyze the stability of the adducts with respect to dissociation. Stoichiometric reaction of the isolated adducts with two representative series of organic electrophiles-namely, aryl halides and diazonium salts-demonstrate the relative reactivities of the anionic diboron compounds as nucleophilic boryl anion sources.

  3. Synthesis and characterization of petal type CZTS by stacked layer reactive sputtering

    NASA Astrophysics Data System (ADS)

    Singh, Om Pal; Parmar, R.; Gour, K. S.; Dalai, M. K.; Tawale, Jai; Singh, S. P.; Singh, Vidya Nand

    2015-12-01

    Here we present a method to grow the petal type structure of CZTS thin film on soda lime glass substrate using the stacked layer reactive sputtering and post-depostion annealing in N2 atmosphere. Optical bandgap of the petal type structure of CZTS was determined using UV-VIS spectroscopy and the value was 1.5 eV. In XRD analysis, (112) plane having highest intensity and other supporting planes with low intensity peaks corresponding to (200), (220) and (312) revealed the presence of CZTS phase. It was further confirmed by the Raman analysis, where the Raman peaks at 288 cm-1, 335 cm-1 and 353 cm-1 revealed the presence of CZTS phase. Petal type growth was observed in the scanning electron microscopy analysis. Elemental analysis was done by the EDAX. In EDAX analysis, It is observed that sample was Sn rich which may be responsible for petal type growth. Petal type growth of CZTS may be helpful in increasing the performance of the CZTS based thin film solar cell by phenomena of light scattering and enhanced surface area.

  4. Synthesis of copper nitride films doped with Fe, Co, or Ni by reactive magnetron sputtering

    SciTech Connect

    Yang, Jianbo; Huang, Saijia; Wang, Zhijiao; Hou, Yuxuan; Shi, Yuyu; Zhang, Jian; Yang, Jianping Li, Xing'ao

    2014-09-01

    Copper nitride (Cu{sub 3}N) and Fe-, Co-, and Ni-doped Cu{sub 3}N films were prepared by reactive magnetron sputtering. The films were deposited on silicon substrates at room temperature using pure Cu target and metal chips. The molar ratio of Cu to N atoms in the as-prepared Cu{sub 3}N film was 2.7:1, which is comparable with the stoichiometry ratio 3:1. X-ray diffraction measurements showed that the films were composed of Cu{sub 3}N crystallites with anti-ReO{sub 3} structure and adopted different preferred orientations. The reflectance of the four samples decreased in the wavelength range of 400–830 nm, but increased rapidly within wavelength range of 830–1200 nm. Compared with the Cu{sub 3}N films, the resistivity of the doped Cu{sub 3}N films decreased by three orders of magnitude. These changes have great application potential in optical and electrical devices based on Cu{sub 3}N films.

  5. Diazaoxatriangulenium: synthesis of reactive derivatives and conjugation to bovine serum albumin.

    PubMed

    Bora, Ilkay; Bogh, Sidsel A; Rosenberg, Martin; Santella, Marco; Sørensen, Thomas Just; Laursen, Bo W

    2016-01-21

    The azaoxa-triangulenium dyes are characterised by emission in the red and a long fluorescence lifetime (up to 25 ns). These properties have been widely explored for the azadioxatrianguelnium (ADOTA) dye. Here, the syntheses of reactive maleimide and NHS-ester forms of the diazaoxatriangulenium (DAOTA) system are reported. The DAOTA fluorophore was conjugated to bovine serum albumin (BSA) and investigated in comparison to the corresponding ADOTA-BSA conjugate. It was found that the fluorescence of DAOTA experienced a significantly higher degree of solvent quenching if compared to ADOTA as non-conjugated dyes in aqueous solution, while the fluorescence quenching observed upon conjugation to BSA was significantly reduced for DAOTA when compared to ADOTA. The differences in observed quenching for the conjugates can be explained by the different electronic structures of the dyes, which renders DAOTA significantly less prone to reductive photoinduced electron transfer (PET) quenching from e.g. tryptophan. We conclude that DAOTA, with emission in the red and inherent resistance to PET quenching, is an ideal platform for the development of long fluorescence lifetime probes for time-resolved imaging and fluorescence polarisation assay.

  6. Synthesis and reactivity of a mononuclear non-haem cobalt(IV)-oxo complex

    PubMed Central

    Wang, Bin; Lee, Yong-Min; Tcho, Woon-Young; Tussupbayev, Samat; Kim, Seoung-Tae; Kim, Yujeong; Seo, Mi Sook; Cho, Kyung-Bin; Dede, Yavuz; Keegan, Brenna C.; Ogura, Takashi; Kim, Sun Hee; Ohta, Takehiro; Baik, Mu-Hyun; Ray, Kallol; Shearer, Jason; Nam, Wonwoo

    2017-01-01

    Terminal cobalt(IV)–oxo (CoIV–O) species have been implicated as key intermediates in various cobalt-mediated oxidation reactions. Herein we report the photocatalytic generation of a mononuclear non-haem [(13-TMC)CoIV(O)]2+ (2) by irradiating [CoII(13-TMC)(CF3SO3)]+ (1) in the presence of [RuII(bpy)3]2+, Na2S2O8, and water as an oxygen source. The intermediate 2 was also obtained by reacting 1 with an artificial oxidant (that is, iodosylbenzene) and characterized by various spectroscopic techniques. In particular, the resonance Raman spectrum of 2 reveals a diatomic Co–O vibration band at 770 cm−1, which provides the conclusive evidence for the presence of a terminal Co–O bond. In reactivity studies, 2 was shown to be a competent oxidant in an intermetal oxygen atom transfer, C–H bond activation and olefin epoxidation reactions. The present results lend strong credence to the intermediacy of CoIV–O species in cobalt-catalysed oxidation of organic substrates as well as in the catalytic oxidation of water that evolves molecular oxygen. PMID:28337985

  7. Genistein Precipitated Hypothyroidism, Altered Leptin and C-Reactive Protein Synthesis in Pregnant Rats.

    PubMed

    Awobajo, F O; Onokpite, B O; Ali, Y M; Babaleye, T A; Uzor, P O; Tijani, K O

    2015-12-20

    Genistein is an isoflavone constituent of soya. This study examined the mechanism by which genistein produced adverse effects in pregnant laboratory rats. Pregnant rats were divided into control (Con) and genistein (Gen) force fed (2 mg/kg) groups. At terminal gestation day (GD) ranging from 0-20, the rats were sacrificed, and blood samples and amniotic fluids were collected. Thyroid hormone, C-reactive protein (CRP) and leptin assay was carried using the blood samples. Leptin was also assayed in the placenta and amniotic fluid supernatant. Oral exposure of pregnant rats to genistein significantly altered maternal T3, (GD18; Con 1.65 ± 0.01, Gen 1.03 ± 0.04 nmol/L), T4 (GD6; Con 29.60 ± 0.00, Gen 36.04 ± 1.29 nmol/L), Leptin (Placenta GD20; Con 0.08 ± 0.01, Gen 0.31 ± 0.02 ng/ml, amniotic fluid ;GD 20; Con 0.02 ± 0.00, Gen 0.35 ± 0.05 ng/ml) in genistein group. These changes were accompanied with loss of embryonic implants and a decrease in fetal and placental weights. The CRP level was significantly decreased and increased at the onset and toward late pregnancy respectively. Oral exposure of pregnant rats to genistein precipitated hypothyroidism, altered some metabolic hormones with a reduction in fetal and placental growth and increased resorption of embryonic implants.

  8. Effects of various physical stress factors on mitochondrial function and reactive oxygen species in rat spermatozoa.

    PubMed

    Kim, Suhee; Agca, Cansu; Agca, Yuksel

    2013-01-01

    The aim of the present study was to evaluate the effects of various physical interventions on the function of epididymal rat spermatozoa and determine whether there are correlations among these functional parameters. Epididymal rat spermatozoa were subjected to various mechanical (pipetting, centrifugation and Percoll gradient separation) and anisotonic conditions, and sperm motility, plasma membrane integrity (PMI), mitochondrial membrane potential (MMP) and intracellular reactive oxygen species (ROS) were evaluated. Repeated pipetting caused a loss in motility, PMI and MMP (P<0.05). Minimal centrifugation force (200 g) had no effect on motility, PMI and MMP, whereas an increase in the centrifugation force to 400 g or 600 g decreased sperm function (P<0.005). Percoll gradient separation increased total motility, PMI and MMP (P<0.05). However, the spermatozoa that were subjected to mechanical interventions showed high susceptibility to a ROS stimulant (P<0.005). Anisotonic conditions decreased motility, PMI and MMP, and hypotonic conditions in particular increased basal ROS (P<0.05). In correlation tests, there were strong positive correlations among total motility, PMI and MMP, whereas ROS showed no or negatively weak correlations with the other parameters. In conclusion, the physical interventions may act as important variables, affecting functional parameters of epididymal rat spermatozoa. Therefore, careful consideration and proper protocols for handling of rat spermatozoa and osmotic conditions are required to achieve reliable results and minimise damage.

  9. Effects of various physical stress factors on mitochondrial function and reactive oxygen species in rat spermatozoa

    PubMed Central

    Kim, Suhee; Agca, Cansu; Agca, Yuksel

    2013-01-01

    The aim of the present study was to evaluate the effects of various physical interventions on the function of epididymal rat spermatozoa and determine whether there are correlations among these functional parameters. Epididymal rat spermatozoa were subjected to various mechanical (pipetting, centrifugation and Percoll gradient separation) and anisotonic conditions, and sperm motility, plasma membrane integrity (PMI), mitochondrial membrane potential (MMP) and intracellular reactive oxygen species (ROS) were evaluated. Repeated pipetting caused a loss in motility, PMI and MMP (P < 0.05). Minimal centrifugation force (200g) had no effect on motility, PMI and MMP, whereas an increase in the centrifugation force to 400g or 600g decreased sperm function (P < 0.005). Percoll gradient separation increased total motility, PMI and MMP (P < 0.05). However, the spermatozoa that were subjected to mechanical interventions showed high susceptibility to a ROS stimulant (P < 0.005). Anisotonic conditions decreased motility, PMI and MMP, and hypotonic conditions in particular increased basal ROS (P < 0.05). In correlation tests, there were strong positive correlations among total motility, PMI and MMP, whereas ROS showed no or negatively weak correlations with the other parameters. In conclusion, the physical interventions may act as important variables, affecting functional parameters of epididymal rat spermatozoa. Therefore, careful consideration and proper protocols for handling of rat spermatozoa and osmotic conditions are required to achieve reliable results and minimise damage. PMID:23140582

  10. Path Integrals for Electronic Densities, Reactivity Indices, and Localization Functions in Quantum Systems

    PubMed Central

    Putz, Mihai V.

    2009-01-01

    The density matrix theory, the ancestor of density functional theory, provides the immediate framework for Path Integral (PI) development, allowing the canonical density be extended for the many-electronic systems through the density functional closure relationship. Yet, the use of path integral formalism for electronic density prescription presents several advantages: assures the inner quantum mechanical description of the system by parameterized paths; averages the quantum fluctuations; behaves as the propagator for time-space evolution of quantum information; resembles Schrödinger equation; allows quantum statistical description of the system through partition function computing. In this framework, four levels of path integral formalism were presented: the Feynman quantum mechanical, the semiclassical, the Feynman-Kleinert effective classical, and the Fokker-Planck non-equilibrium ones. In each case the density matrix or/and the canonical density were rigorously defined and presented. The practical specializations for quantum free and harmonic motions, for statistical high and low temperature limits, the smearing justification for the Bohr’s quantum stability postulate with the paradigmatic Hydrogen atomic excursion, along the quantum chemical calculation of semiclassical electronegativity and hardness, of chemical action and Mulliken electronegativity, as well as by the Markovian generalizations of Becke-Edgecombe electronic focalization functions – all advocate for the reliability of assuming PI formalism of quantum mechanics as a versatile one, suited for analytically and/or computationally modeling of a variety of fundamental physical and chemical reactivity concepts characterizing the (density driving) many-electronic systems. PMID:20087467

  11. Path integrals for electronic densities, reactivity indices, and localization functions in quantum systems.

    PubMed

    Putz, Mihai V

    2009-11-10

    The density matrix theory, the ancestor of density functional theory, provides the immediate framework for Path Integral (PI) development, allowing the canonical density be extended for the many-electronic systems through the density functional closure relationship. Yet, the use of path integral formalism for electronic density prescription presents several advantages: assures the inner quantum mechanical description of the system by parameterized paths; averages the quantum fluctuations; behaves as the propagator for time-space evolution of quantum information; resembles Schrödinger equation; allows quantum statistical description of the system through partition function computing. In this framework, four levels of path integral formalism were presented: the Feynman quantum mechanical, the semiclassical, the Feynman-Kleinert effective classical, and the Fokker-Planck non-equilibrium ones. In each case the density matrix or/and the canonical density were rigorously defined and presented. The practical specializations for quantum free and harmonic motions, for statistical high and low temperature limits, the smearing justification for the Bohr's quantum stability postulate with the paradigmatic Hydrogen atomic excursion, along the quantum chemical calculation of semiclassical electronegativity and hardness, of chemical action and Mulliken electronegativity, as well as by the Markovian generalizations of Becke-Edgecombe electronic focalization functions - all advocate for the reliability of assuming PI formalism of quantum mechanics as a versatile one, suited for analytically and/or computationally modeling of a variety of fundamental physical and chemical reactivity concepts characterizing the (density driving) many-electronic systems.

  12. Mitochondrial metabolism, reactive oxygen species, and macrophage function-fishing for insights.

    PubMed

    Hall, Christopher J; Sanderson, Leslie E; Crosier, Kathryn E; Crosier, Philip S

    2014-11-01

    Metabolism and defense mechanisms that protect against pathogens are two fundamental requirements for the survival of multicellular organisms. Research into metabolic disease has revealed these core mechanisms are highly co-dependent. This emerging field of research, termed immunometabolism, focuses on understanding how metabolism influences immunological processes and vice versa. It is now accepted that obesity influences the immune system and that obesity-driven inflammation contributes to many diseases including type 2 diabetes, cardiovascular disease and Alzheimer's disease. The immune response requires the reallocation of nutrients within immune cells to different metabolic pathways to satisfy energy demands and the production of necessary macromolecules. One aspect of immunometabolic research is understanding how these metabolic changes help regulate specific immune cell functions. It is hoped that further understanding of the pathways involved in managing this immunological-metabolic interface will reveal new ways to treat metabolic disease. Given their growing status as principle drivers of obesity-associated inflammation, monocytes/macrophages have received much attention when studying the consequences of inflammation within adipose tissue. Less is known regarding how metabolic changes within macrophages (metabolic reprogramming) influence their immune cell function. In this review, we focus on our current understanding of how monocytes/macrophages alter their intracellular metabolism during the immune response and how these changes dictate specific effector functions. In particular, the immunomodulatory functions of mitochondrial metabolism and mitochondrial reactive oxygen species. We also highlight how the attributes of the zebrafish model system can be exploited to reveal new mechanistic insights into immunometabolic processes.

  13. Synthesis and characterization of carboxylic acid functionalized silicon nanoparticles

    NASA Astrophysics Data System (ADS)

    Shaner, Ted V.

    Silicon nanoparticles are of great interest in a great number of fields. Silicon nanoparticles show great promise particularly in the field of bioimaging. Carboxylic acid functionalized silicon nanoparticles have the ability to covalently bond to biomolecules through the conjugation of the carboxylic acid to an amine functionalized biomolecule. This thesis explores the synthesis of silicon nanoparticles functionalized by both carboxylic acids and alkenes and their carboxylic acid functionality. Also discussed is the characterization of the silicon nanoparticles by the use of x-ray spectroscopy. Finally, the nature of the Si-H bond that is observed on the surface of the silicon nanoparticles will be investigated using photoassisted exciton mediated hydrosilation reactions. The silicon nanoparticles are synthesized from both carboxylic acids and alkenes. However, the lack of solubility of diacids is a significant barrier to carboxylic acid functionalization by a mixture of monoacids and diacids. A synthesis route to overcome this obstacle is to synthesize silicon nanoparticles with terminal vinyl group. This terminal vinyl group is distal to the surface of the silicon nanoparticle. The conversion of the vinyl group to a carboxylic acid is accomplished by oxidative cleavage using ozonolysis. The carboxylic acid functionalized silicon nanoparticles were then successfully conjugated to amine functionalized DNA strand through an n-hydroxy succinimide ester activation step, which promotes the formation of the amide bond. Conjugation was characterized by TEM and polyacrylamide gel electrophoresis (PAGE). The PAGE results show that the silicon nanoparticle conjugates move slower through the polyacrylamide gel, resulting in a significant separation from the nonconjugated DNA. The silicon nanoparticles were then characterized by the use of x-ray absorption near edge spectroscopy (Xanes) and x-ray photoelectron spectroscopy (XPS) to investigate the bonding and chemical

  14. Amine Functionalization via Oxidative Photoredox Catalysis: Methodology Development and Complex Molecule Synthesis.

    PubMed

    Beatty, Joel W; Stephenson, Corey R J

    2015-05-19

    While the use of visible light to drive chemical reactivity is of high importance to the development of environmentally benign chemical transformations, the concomitant use of a stoichiometric electron donor or acceptor is often required to steer the desired redox behavior of these systems. The low-cost and ubiquity of tertiary amine bases has led to their widespread use as reductive additives in photoredox catalysis. Early use of trialkylamines in this context was focused on their role as reductive excited state quenchers of the photocatalyst, which in turn provides a more highly reducing catalytic intermediate. In this Account, we discuss some of the observations and thought processes that have led from our use of amines as reductive additives to their use as complex substrates and intermediates for natural product synthesis. Early attempts by our group to construct key carbon-carbon bonds via free-radical intermediates led to the observation that some trialkylamines readily behave as efficient hydrogen atom donors under redox-active photochemical conditions. In the wake of in-depth mechanistic studies published in the 1970s, 1980s and 1990s, this understanding has in turn allowed for a systematic approach to the design of a number of photochemical methodologies through rational tuning of the amine component. Minimization of the C-H donicity of the amine additive was found to promote desired C-C bond formation in a number of contexts, and subsequent elucidation of the amine's redox fate has sparked a reevaluation of the amine's role from that of reagent to that of substrate. The reactivity of tertiary amines in these photochemical systems is complex, and allows for a number of mechanistic possibilities that are not necessarily mutually exclusive. A variety of combinations of single-electron oxidation, C-H abstraction, deprotonation, and β-scission result in the formation of reactive intermediates such as α-amino radicals and iminium ions. These processes have

  15. Amine Functionalization via Oxidative Photoredox Catalysis: Methodology Development and Complex Molecule Synthesis

    PubMed Central

    2016-01-01

    Conspectus While the use of visible light to drive chemical reactivity is of high importance to the development of environmentally benign chemical transformations, the concomitant use of a stoichiometric electron donor or acceptor is often required to steer the desired redox behavior of these systems. The low-cost and ubiquity of tertiary amine bases has led to their widespread use as reductive additives in photoredox catalysis. Early use of trialkylamines in this context was focused on their role as reductive excited state quenchers of the photocatalyst, which in turn provides a more highly reducing catalytic intermediate. In this Account, we discuss some of the observations and thought processes that have led from our use of amines as reductive additives to their use as complex substrates and intermediates for natural product synthesis. Early attempts by our group to construct key carbon–carbon bonds via free-radical intermediates led to the observation that some trialkylamines readily behave as efficient hydrogen atom donors under redox-active photochemical conditions. In the wake of in-depth mechanistic studies published in the 1970s, 1980s and 1990s, this understanding has in turn allowed for a systematic approach to the design of a number of photochemical methodologies through rational tuning of the amine component. Minimization of the C–H donicity of the amine additive was found to promote desired C–C bond formation in a number of contexts, and subsequent elucidation of the amine’s redox fate has sparked a reevaluation of the amine’s role from that of reagent to that of substrate. The reactivity of tertiary amines in these photochemical systems is complex, and allows for a number of mechanistic possibilities that are not necessarily mutually exclusive. A variety of combinations of single-electron oxidation, C–H abstraction, deprotonation, and β-scission result in the formation of reactive intermediates such as α-amino radicals and iminium ions

  16. Synthesis and phase behavior of end-functionalized associating polymers

    NASA Astrophysics Data System (ADS)

    Wrue, Michelle H.

    We have explored polymer blend phase behavior in the presence of multiple hydrogen bonding end-groups. This work details the synthesis of functionalized polymers and their subsequent use in miscibility studies. The synthesis of end-functionalized hydrogen bonding polymers and the investigation of their physical properties and miscibility is presented. Mono-functional and telechelic ureidopyrimidinone (UPy) functionalized polymers were prepared by two main routes: post-polymerization functionalization (of commercially available or synthesized polymers); and polymerization of monomers using a functionalized initiator. UPy-functionalized polymers were prepared with a variety of polymer backbones including poly(ethylene oxide)s; poly(butadiene)s, poly(dimethyl siloxanxe)s; poly(styrene)s and poly(methyl methacrylate)s. The most successful route to polymers with UPy end-groups was atom transfer radical polymerization (ATRP) using a UPy-functionalized initiator, followed by atom transfer radical coupling (ATRC). The incorporation of ureidopyrimidinone end-groups was shown to affect the physical properties of the polymer backbone. Parent polymers that were liquids became viscous liquids or waxy solids upon UPy-functionalization of chain end. UPy-functionalization of a hydroxyl-terminated polybutadiene (HO-PB-OH) resulted in a waxy solid while the HO-PB-OH precursor was a viscous liquid. The thermal properties of functionalized polymers also differed from those of the unfunctionalized parent polymers. Hot-stage optical microscopy revealed that UPy-functionalized PEO displayed a depressed melting point relative to the analogous unfunctionalized precursor. Differential scanning calorimetry was also used to investigate the synthesized UPy-polymers. UPy-functionalized polystyrenes and poly(methyl methacrylate)s showed an increased T g compared to the equivalent homopolymer standards. This increased Tg was determined to be dependent upon the fraction of UPy groups present and

  17. Green synthesis of iron nanoparticles by various tea extracts: Comparative study of the reactivity

    NASA Astrophysics Data System (ADS)

    Huang, Lanlan; Weng, Xiulan; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

    2014-09-01

    Iron nanoparticles (Fe NPs) are often synthesized using sodium borohydride with aggregation, which is a high cost process and environmentally toxic. To address these issues, Fe NPs were synthesized using green methods based on tea extracts, including green, oolong and black teas. The best method for degrading malachite green (MG) was Fe NPs synthesized by green tea extracts because it contains a high concentration of caffeine/polyphenols which act as both reducing and capping agents in the synthesis of Fe NPs. These characteristics were confirmed by a scanning electron microscope (SEM), UV-visible (UV-vis) and specific surface area (BET). To understand the formation of Fe NPs using various tea extracts, the synthesized Fe NPs were characterized by SEM, X-ray energy-dispersive spectrometer (EDS), and X-ray diffraction (XRD). What emerged were different sizes and concentrations of Fe NPs being synthesized by tea extracts, leading to various degradations of MG. Furthermore, kinetics for the degradation of MG using these Fe NPs fitted well to the pseudo first-order reaction kinetics model with more than 20 kJ/mol activation energy, suggesting a chemically diffusion-controlled reaction. The degradation mechanism using these Fe NPs included adsorption of MG to Fe NPs, oxidation of iron, and cleaving the bond that was connected to the benzene ring.

  18. Green synthesis of iron nanoparticles by various tea extracts: comparative study of the reactivity.

    PubMed

    Huang, Lanlan; Weng, Xiulan; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravendra

    2014-09-15

    Iron nanoparticles (Fe NPs) are often synthesized using sodium borohydride with aggregation, which is a high cost process and environmentally toxic. To address these issues, Fe NPs were synthesized using green methods based on tea extracts, including green, oolong and black teas. The best method for degrading malachite green (MG) was Fe NPs synthesized by green tea extracts because it contains a high concentration of caffeine/polyphenols which act as both reducing and capping agents in the synthesis of Fe NPs. These characteristics were confirmed by a scanning electron microscope (SEM), UV-visible (UV-vis) and specific surface area (BET). To understand the formation of Fe NPs using various tea extracts, the synthesized Fe NPs were characterized by SEM, X-ray energy-dispersive spectrometer (EDS), and X-ray diffraction (XRD). What emerged were different sizes and concentrations of Fe NPs being synthesized by tea extracts, leading to various degradations of MG. Furthermore, kinetics for the degradation of MG using these Fe NPs fitted well to the pseudo first-order reaction kinetics model with more than 20 kJ/mol activation energy, suggesting a chemically diffusion-controlled reaction. The degradation mechanism using these Fe NPs included adsorption of MG to Fe NPs, oxidation of iron, and cleaving the bond that was connected to the benzene ring.

  19. Synthesis, structure, and reactivity of N-benzoyl iminophosphoranes ortho lithiated at the benzoyl group.

    PubMed

    Aguilar, David; Fernández, Ignacio; Cuesta, Luciano; Yañez-Rodríguez, Víctor; Soler, Tatiana; Navarro, Rafael; Urriolabeitia, Esteban P; López Ortiz, Fernando

    2010-10-01

    Ortho lithiation of N-benzamido-P,P,P-triaryliminophosphoranes through deprotonation with alkyllithium bases was achieved with ortho-C═O and ortho-P═N chemoselectivity. However, the synthetic scope of these processes was rather limited. Ortho-lithiated N-benzamido-P,P,P-triphenyliminophosphorane 8 was efficiently prepared via lithium/halogen exchange of the corresponding ortho-brominated precursor with s-BuLi in THF at -90 °C. The reaction of 8 with a variety of electrophiles provides an easy and mild method for the regioselective synthesis of ortho-modified iminophosphoranes via C-C (alkylation and hydroxyalkylation) and C-X (X = I, Si, P, Sn, and Hg) bond-forming reactions. NMR characterization of 8 in THF solution showed that 8 exists as an equilibrium mixture of one monomer and two dimers. The Li atoms of these species become members of five-membered rings through chelation by the ortho-metalated carbon and the carbonyl oxygen. The dimers differ in the relative orientation of the two chelates with respect to the plane defined by the C(2)Li(2) core. The equilibrium between all species is established by splitting the dimers into monomers and subsequent recombination with formation of a different dimer.

  20. Frequency of mentally stimulating activities modifies the relationship between cardiovascular reactivity and executive function in old age.

    PubMed

    Lin, Feng; Heffner, Kathi; Mapstone, Mark; Chen, Ding-Geng Din; Porsteisson, Anton

    2014-11-01

    Recent evidence suggests that younger and middle-age adults who show greater cardiovascular reactivity (CVR) to acute mental stress demonstrate better reasoning and memory skills. The purpose of this study was to examine whether older adults would exhibit a similar positive association between CVR and executive function and whether regular engagement in mentally stimulating activities (MSA) would moderate this association. Secondary cross-sectional analysis. Three clinical research centers in the Midwest and on the West Coast and East Coast. A total of 487 older adults participating in an ongoing national survey. Heart rate (HR) and low-frequency (LF) and high-frequency (HF) domains of heart rate variability (HRV) were measured at baseline and in response to standard mental stress tasks (Stroop color word task and mental arithmetic). Executive function was measured separately from the stress tasks by using five neuropsychological tests. MSA was measured by self-reported frequency of six common MSA. Higher HR reactivity was associated with better executive function after controlling for demographic and health characteristics and baseline HR, and the interaction between HR reactivity and MSA was significant for executive function. Higher LF-HRV reactivity was also associated with executive function, but subsequent analyses indicated that frequency of MSA was the strongest predictor of executive function in models that included LF-HRV or HF-HRV. Higher HR reactivity to acute psychological stress is related to better executive function in older adults. For those with lower HR reactivity, engaging frequently in MSA produced compensatory benefits for executive function. Copyright © 2014 American Association for Geriatric Psychiatry. Published by Elsevier Inc. All rights reserved.

  1. Frequency of Mentally Stimulating Activities Modifies the Relationship between Cardiovascular Reactivity and Executive Function in Old Age

    PubMed Central

    Lin, Feng; Heffner, Kathi; Mapstone, Mark; Chen, Ding-Geng (Din); Porsteisson, Anton

    2013-01-01

    Objective Recent evidence suggests that younger- and middle-age adults who show greater cardiovascular reactivity (CVR) to acute mental stress demonstrate better reasoning and memory skills. The purpose of this study was to examine whether older adults would show a similar positive association between CVR and executive function, and whether regular engagement in mentally stimulating activities (MSA) would moderate this association. Design Secondary cross-sectional analysis. Setting Three general clinical research centers located in the West Coast, Midwest, and East Coast. Participants 487 older adults participating in an on-going national survey. Measurements Heart rate (HR) and low (LF) and high frequency (HF) domains of heart rate variability (HRV) were measured at baseline and in response to standard mental stress tasks (Stroop color word task and mental arithmetic). Executive function was measured separately from the stress tasks using five neuropsychological tests. MSA was measured by self-report frequency of six common mentally stimulating activities. Results Higher HR reactivity was associated with better executive function after controlling for demographic and health variables and baseline HR activity and the interaction between HR reactivity and MSA was significant for executive function. Higher LF-HRV reactivity was also associated with executive function, but subsequent analyses indicated that frequency of MSA was the strongest predictor of executive function in models that included LF- or HF-HRV. Conclusions Higher HR reactivity to acute psychological stress is related to better executive function in older adults. For those with lower HR reactivity, engaging frequently in MSA showed significant compensatory benefits for executive function. PMID:23891367

  2. Cysteine functionalized copper organosol: synthesis, characterization and catalytic application

    NASA Astrophysics Data System (ADS)

    Panigrahi, Sudipa; Kundu, Subrata; Basu, Soumen; Praharaj, Snigdhamayee; Jana, Subhra; Pande, Surojit; Ghosh, Sujit Kumar; Pal, Anjali; Pal, Tarasankar

    2006-11-01

    We herein report a facile one-pot synthesis, stabilization, redispersion and Cu-S interaction of L-cysteine and dodecanethiol (DDT) protected copper organosol in toluene from precursor copper stearate using sodium borohydride in toluene under a nitrogen atmosphere. Surface modification of the synthesized copper organosol with an amino acid L-cysteine and an alkanethiol (dodecanethiol, DDT) is accomplished by a thiolate bond between the used ligands and nanoparticle surface. The cysteine molecule binds the copper surface via a thiolate and amine linkage but not through electrostatic interaction with the carboxylate group due to the solvent polarity and dielectric medium. Fourier transform infrared (FTIR) analysis was performed to confirm the surface functionalization of the amino acid and DDT to the copper surface. Copper organosol has been characterized by optical spectroscopy (UV/vis), transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS) and x-ray diffraction (XRD). The as-synthesized particles are spherical in shape and exhibit a Mie scattering profile with an absorption maxima in the visible range. Copper nanoparticles capped by cysteine and/or DDT in non-aqueous media are found to represent an interesting catalytic approach for the synthesis of octylphenyl ether.

  3. Alphavirus RNA synthesis and non-structural protein functions

    PubMed Central

    Rupp, Jonathan C.; Sokoloski, Kevin J.; Gebhart, Natasha N.

    2015-01-01

    The members of the genus Alphavirus are positive-sense RNA viruses, which are predominantly transmitted to vertebrates by a mosquito vector. Alphavirus disease in humans can be severely debilitating, and depending on the particular viral species, infection may result in encephalitis and possibly death. In recent years, alphaviruses have received significant attention from public health authorities as a consequence of the dramatic emergence of chikungunya virus in the Indian Ocean islands and the Caribbean. Currently, no safe, approved or effective vaccine or antiviral intervention exists for human alphavirus infection. The molecular biology of alphavirus RNA synthesis has been well studied in a few species of the genus and represents a general target for antiviral drug development. This review describes what is currently understood about the regulation of alphavirus RNA synthesis, the roles of the viral non-structural proteins in this process and the functions of cis-acting RNA elements in replication, and points to open questions within the field. PMID:26219641

  4. Screening of active metals for reactive adsorption desulfurization adsorbent using density functional theory

    NASA Astrophysics Data System (ADS)

    Wang, Lei; Zhao, Liang; Xu, Chunming; Wang, Yuxian; Gao, Jinsen

    2017-03-01

    To explore characteristics of active metals for reactive adsorption desulfurization (RADS) technology, the adsorption of thiophene on M (100) (M = Cr, Mo, Co, Ni, Cu, Au, and Ag) surfaces was systematically studied by density functional theory with vdW correction (DFT + D3). We found that, in all case, the most stable molecular adsorption site was the hollow site and adsorptive capabilities of thiophene followed the order: Cr > Mo > Co ≈ Ni > Cu > Au ≈ Ag. By analyzing the nature of binding between thiophene and corresponding metals and the electronic structure of metals, the excessive activities of Cr and Mo were found to have a negative regeneration, the passive activities of Au and Ag were found to have an inactive adsorption for RADS adsorbent alone, while Ni and Co have appropriate characteristics as the active metals for RADS, followed by Cu.

  5. Athymic (nude) mice fail to delete functional self-reactive helper T cells.

    PubMed

    Caulfield, M J; Stanko, D; Isaak, D D

    1993-09-01

    We have examined the thymic requirement for the antibody response to a foreign antigen coupled to self erythrocytes. We find that self erythrocytes mediate thymus-independent, carrier specific help for the antibody response to the pneumococcal cell wall polysaccharide antigen, PnC. Thus, athymic nude mice gave a high primary antibody plaque-forming cell (PFC) response to PnC-mouse RBC but a low response to PnC coupled to sheep or burro RBC. The meager response to PnC coupled to foreign RBCs could not be attributed to antigenic competition since the response to the carrier (burro RBC) was < 100 PFC per spleen. Reconstitution of nude mice with splenic T cells from euthymic mice enhanced rather than suppressed the antibody response to PnC-mouse RBC. The results document that in the absence of thymic deletion, functional self-reactive helper cells persist in the nude mouse.

  6. Additive, modular functionalization of reactive self-assembled monolayers: toward the fabrication of multilevel optical storage media.

    PubMed

    Gentili, Denis; Barbalinardo, Marianna; Manet, Ilse; Durso, Margherita; Brucale, Marco; Mezzi, Alessio; Melucci, Manuela; Cavallini, Massimiliano

    2015-04-28

    We report a novel strategy based on iterative microcontact printing, which provides additive, modular functionalization of reactive SAMs by different functional molecules. We demonstrate that after printing the molecules form an interpenetrating network at the SAM surface preserving their individual properties. We exploited the process by fabricating new optical storage media that consist of a multilevel TAG.

  7. Impaired microvascular reactivity and endothelial function in patients with Cushing's syndrome: influence of arterial hypertension.

    PubMed

    Prázný, M; Jezková, J; Horová, E; Lazárová, V; Hána, V; Kvasnicka, J; Pecen, L; Marek, J; Skrha, J; Krsek, M

    2008-01-01

    The aim of the study was to evaluate skin microvascular reactivity (MVR) and possible influencing factors (fibrinolysis, oxidative stress, and endothelial function) in patients with Cushing's syndrome. Twenty-nine patients with active Cushing's syndrome (ten of them also examined after a successful operation) and 16 control subjects were studied. Skin MVR was measured by laser Doppler flowmetry during post-occlusive (PORH) and thermal hyperemia (TH). Malondialdehyde and Cu,Zn-superoxide dismutase were used as markers of oxidative stress. Fibrinolysis was estimated by tissue plasminogen activator (tPA) and its inhibitor (PAI-1). N-acetyl-beta-glucosaminidase, E-selectin, P-selectin, and ICAM-1 were used as markers of endothelial function. Oxidative stress and endothelial dysfunction was present in patients with hypercortisolism, however, increased concentration of ICAM-1 was also found in patients after the operation as compared to controls (290.8+/-74.2 vs. 210.9+/-56.3 ng.ml(-1), p<0.05). Maximal perfusion was significantly lower in patients with arterial hypertension during PORH and TH (36.3+/-13.0 vs. 63.3+/-32.4 PU, p<0.01, and 90.4+/-36.6 vs. 159.2+/-95.3 PU, p<0.05, respectively) and similarly the velocity of perfusion increase during PORH and TH was lower (3.2+/-1.5 vs. 5.2+/-3.4 PU.s(-1), p<0.05, and 0.95+/-0.6 vs. 1.8+/-1.1 PU.s(-1), p<0.05, respectively). The most pronounced impairment of microvascular reactivity was present in patients with combination of arterial hypertension and diabetes mellitus.

  8. Thiol-functionalized nanogels as reactive plasticizers for crosslinked polymer networks.

    PubMed

    Saraswathy, Manju; Stansbury, Jeffrey W; Nair, Devatha P

    2017-10-01

    Significant efforts have been expended to mitigate plasticizer migration from crosslinked methacrylic and poly(vinyl chloride) polymer networks by synthesizing reactive plasticizers that can blend homogenously within the networks to reduce polymer property change, acute toxicity and downstream environmental effects of plasticizer migration with limited and varying amount of success. We hypothesized that appropriate thiol-functionalized nanogels synthesized using the same monomers as the parent network to generate highly compact, crosslinked structures will form thermally stable, homogenous networks and perform as optimal reactive plasticizers. Nanogels were synthesized via a thiol-Michael addition solution polymerization and incorporated at different mass ratios within a polyethylene glycol 400 urethane dimethacrylic monomer to form photo-crosslinked networks. While maintaining the inherent hydrolytic stability, thermal stability and biocompatibility of the parent matrix at ~99% acrylic group conversion, the PEG400 urethane dimethacrylic -nanogel networks retained optical clarity with >90% visible light transmission at 20wt% nanogel concentration within the matrix. The addition of the nanogels also enhanced the elongation of the parent matrix by up to 320%, while a 37°C reduction in glass transition temperature (∆Tg) and ≥50% reduction in modulus was observed. A 52% reduction in the shrinkage stress of the material was also noted. The results indicate that the application of thiol-functionalized nanogels as plasticizers to alter the bulk properties of the parent matrix while mitigating plasticizer migration by covalently crosslinking the nanogels within the polymer matrix provides a simple yet efficient technique to generate network-specific plasticizers with the ability to alter targeted properties within polymers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Mitochondrial Reactive Oxygen Species Production in Excitable Cells: Modulators of Mitochondrial and Cell Function

    PubMed Central

    Camara, Amadou K. S.

    2009-01-01

    Abstract The mitochondrion is a major source of reactive oxygen species (ROS). Superoxide (O2•−) is generated under specific bioenergetic conditions at several sites within the electron-transport system; most is converted to H2O2 inside and outside the mitochondrial matrix by superoxide dismutases. H2O2 is a major chemical messenger that, in low amounts and with its products, physiologically modulates cell function. The redox state and ROS scavengers largely control the emission (generation scavenging) of O2•−. Cell ischemia, hypoxia, or toxins can result in excess O2•− production when the redox state is altered and the ROS scavenger systems are overwhelmed. Too much H2O2 can combine with Fe2+ complexes to form reactive ferryl species (e.g., Fe(IV) = O•). In the presence of nitric oxide (NO•), O2•− forms the reactant peroxynitrite (ONOO−), and ONOOH-induced nitrosylation of proteins, DNA, and lipids can modify their structure and function. An initial increase in ROS can cause an even greater increase in ROS and allow excess mitochondrial Ca2+ entry, both of which are factors that induce cell apoptosis and necrosis. Approaches to reduce excess O2•− emission include selectively boosting the antioxidant capacity, uncoupling of oxidative phosphorylation to reduce generation of O2•− by inducing proton leak, and reversibly inhibiting electron transport. Mitochondrial cation channels and exchangers function to maintain matrix homeostasis and likely play a role in modulating mitochondrial function, in part by regulating O2•− generation. Cell-signaling pathways induced physiologically by ROS include effects on thiol groups and disulfide linkages to modify posttranslationally protein structure to activate/inactivate specific kinase/phosphatase pathways. Hypoxia-inducible factors that stimulate a cascade of gene transcription may be mediated physiologically by ROS. Our knowledge of the role played by ROS and their scavenging systems in

  10. Synthesis and characterization of functionalized methacrylates for coatings and biomedical applications

    NASA Astrophysics Data System (ADS)

    Shemper, Bianca Sadicoff

    The research presented in this dissertation involves the design of polymers for biomaterials and for coatings applications. The development of non-wettable, hard UV-curing, or reactive coatings is discussed. The biomaterials section involves the syntheses of linear and star-like polymers of the functionalized monomer poly(propylene glycol) monomethacrylate (PPGM) via atom transfer radical polymerization (ATRP) (Chapter II). Its copolymerization with a perfluoroalkyl ethyl methacrylate monomer (1H,1H,2H,2H-heptadecafluorodecyl methacrylate) and the syntheses of linear and star-like amphiphilic copolymers containing the fluorinated monomer and poly(ethyleneglycol) methyl ether methacrylate (MPEGMA) are discussed in Chapter III. The four-arm amphiphilic block copolymer obtained showed unique associative properties leading to micellization in selective solvents. Chapter IV includes research involving the design of films with low surface energy by incorporating fluorine into the polymer. The synthesis, characterization and polymerization of a perfluoroalkylether-substituted methacrylic acid (C8F7) are discussed, and the properties of coatings obtained after its photopolymerization on different substrates are evaluated to confirm formation of low-surface energy polymeric coatings. Subsequently, hard coatings based on methyl (alpha-hydroxymethyl)acrylate (MHMA) were prepared via photopolymerization using UV-light. Firstly, mechanistic investigations into the photopolymerization behavior of (alpha-hydroxymethyl)acrylates (RHMA's) are reported (Chapter V). RHMA derivatives were photopolymerized with various multifunctional acrylates and methacrylates and the effect of crosslinker type and degree of functionality on photopolymerization rates and conversions was investigated. Then, in Chapter VI the synthesis of a series of new crosslinkers is described and their photopolymerization kinetics was investigated in bulk. The effect of these novel crosslinkers on the

  11. Synthesis of porous chitosan-polyaniline/ZnO hybrid composite and application for removal of reactive orange 16 dye.

    PubMed

    Kannusamy, Pandiselvi; Sivalingam, Thambidurai

    2013-08-01

    For the first time, chitosan-polyaniline/ZnO hybrids were prepared through a polymerization of aniline hydrochloride in the presence of ZnCl2 and chitosan. The hybrid materials were characterized by FT-IR, BET, SEM, UV-vis spectra and XRD analysis. From the BET and SEM micrographs, the introduction of ZnO nanoparticles into chitosan-polyaniline hybrid could obviously increase the porosity due to good possibility for dye adsorption. Adsorption experiments were carried out as a function of contact time, concentration of dye, adsorbent dosage and pH using reactive orange 16 as a model pollutant. The adsorption equilibrium data were fitted well to the Langmuir isotherm equation, with maximum adsorption capacity value was found to be 476.2mgg(-1). Adsorption kinetics was best described by the pseudo-second-order model agreed well with the experimental data and good correlation (R(2)>0.999). Photocatalytic degradation of dye under UV irradiation at pH 5.8 has also been examined. FT-IR spectrum clearly indicates that before adsorption of hybrid showed the functional groups of chitosan and polyaniline, whereas the dye adsorbed hybrid only present the dye molecules and ZnO. Based on the results of present investigation, the introduction of ZnCl2 into chitosan-polyaniline hybrid will enhance the adsorption of reactive dyes and photocatalytic degradation.

  12. Reactivity of a Carbon-Supported Single-Site Molybdenum Dioxo Catalyst for Biodiesel Synthesis

    SciTech Connect

    Mouat, Aidan R.; Lohr, Tracy L.; Wegener, Evan C.; Miller, Jeffrey T.; Delferro, Massimiliano; Stair, Peter C.; Marks, Tobin J.

    2016-08-23

    A single-site molybdenum dioxo catalyst, (Oc)2Mo(=O)2@C, was prepared via direct grafting of MoO2Cl2(dme) (dme = 1,2-dimethoxyethane) on high-surface- area activated carbon. The physicochemical and chemical properties of this catalyst were fully characterized by N2 physisorption, ICP-AES/OES, PXRD, STEM, XPS, XAS, temperature-programmed reduction with H2 (TPR-H2), and temperature-programmed NH3 desorption (TPD-NH3). The single-site nature of the Mo species is corroborated by XPS and TPR-H2 data, and it exhibits the lowest reported MoOx Tmax of reduction reported to date, suggesting a highly reactive MoVI center. (Oc)2Mo(=O)2@C catalyzes the transesterification of a variety of esters and triglycerides with ethanol, exhibiting high activity at moderate temperatures (60-90 °C) and with negligible deactivation. (Oc)2Mo(=O)2@C is resistant to water and can be recycled at least three times with no loss of activity. The transesterification reaction is determined experimentally to be first order in [ethanol] and first order in [Mo] with ΔH = 10.5(8) kcal mol-1 and ΔS = -32(2) eu. The low energy of activation is consistent with the moderate conditions needed to achieve rapid turnover. This highly active carbon-supported single-site molybdenum dioxo species is thus an efficient, robust, and lowcost catalyst with significant potential for transesterification processes.

  13. Synthesis, structure, and reactivity of high oxidation state silver fluorides and related compounds

    SciTech Connect

    Lucier, George Michael

    1995-05-01

    This thesis has been largely concerned with defining the oxidizing power of Ag(III) and Ag(II) in anhydrous hydrogen fluoride (aHF) solution. Emphasis was on cationic species, since in a cation the electronegativity of a given oxidation state is greatest. Cationic Ag(III) solv has a short half life at ordinary temperatures, oxidizing the solvent to elemental fluorine with formation of Ag(II). Salts of such a cation have not yet been preparable, but solutions which must contain such a species have proved to be effective and powerful oxidizers. In presence of PtF6-, RuF6-, or RhF6-, Ag(III) solv effectively oxidizes the anions to release the neutral hexafluorides. Such reactivity ranks cationic Ag(III) as the most powerfully oxidizing chemical agent known as far. Unlike its trivalent relative Ag (II) solv is thermodynamically stable in acid aHF. Nevertheless, it oxidizes IrF6- to IrF6 at room temperature, placing its oxidizing potential not more than 2 eV below that of cationic Ag(III). Range of Ag2+ (MF6-2 salts attainable in aHF has been explored. An anion must be stable with respect to electron loss to Ag2+. The anion must also be a poor F- donor; otherwise, either AgF+ salts or AgF2 are generated.

  14. Synthesis of Self-Assembled Multifunctional Nanocomposite Catalysts with Highly Stabilized Reactivity and Magnetic Recyclability

    PubMed Central

    Yu, Xu; Cheng, Gong; Zheng, Si-Yang

    2016-01-01

    In this paper, a multifunctional Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite catalyst with highly stabilized reactivity and magnetic recyclability was synthesized by a self-assembled method. The magnetic Fe3O4 nanoparticles were coated with a thin layer of the SiO2 to obtain a negatively charged surface. Then positively charged poly(ethyleneimine) polymer (PEI) was self-assembled onto the Fe3O4@SiO2 by electrostatic interaction. Next, negatively charged glutathione capped gold nanoparticles (GSH-AuNPs) were electrostatically self-assembled onto the Fe3O4@SiO2@PEI. After that, silver was grown on the surface of the nanocomposite due to the reduction of the dopamine in the alkaline solution. An about 5 nm thick layer of polydopamine (PDA) was observed to form the Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was carefully characterized by the SEM, TEM, FT-IR, XRD and so on. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite shows a high saturation magnetization (Ms) of 48.9 emu/g, which allows it to be attracted rapidly to a magnet. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was used to catalyze the reduction of p-nitrophenol (4-NP) to p-aminophenol (4-AP) as a model system. The reaction kinetic constant k was measured to be about 0.56 min−1 (R2 = 0.974). Furthermore, the as-prepared catalyst can be easily recovered and reused for 8 times, which didn’t show much decrease of the catalytic capability. PMID:27147586

  15. Synthesis of Self-Assembled Multifunctional Nanocomposite Catalysts with Highly Stabilized Reactivity and Magnetic Recyclability.

    PubMed

    Yu, Xu; Cheng, Gong; Zheng, Si-Yang

    2016-05-05

    In this paper, a multifunctional Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite catalyst with highly stabilized reactivity and magnetic recyclability was synthesized by a self-assembled method. The magnetic Fe3O4 nanoparticles were coated with a thin layer of the SiO2 to obtain a negatively charged surface. Then positively charged poly(ethyleneimine) polymer (PEI) was self-assembled onto the Fe3O4@SiO2 by electrostatic interaction. Next, negatively charged glutathione capped gold nanoparticles (GSH-AuNPs) were electrostatically self-assembled onto the Fe3O4@SiO2@PEI. After that, silver was grown on the surface of the nanocomposite due to the reduction of the dopamine in the alkaline solution. An about 5 nm thick layer of polydopamine (PDA) was observed to form the Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was carefully characterized by the SEM, TEM, FT-IR, XRD and so on. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite shows a high saturation magnetization (Ms) of 48.9 emu/g, which allows it to be attracted rapidly to a magnet. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was used to catalyze the reduction of p-nitrophenol (4-NP) to p-aminophenol (4-AP) as a model system. The reaction kinetic constant k was measured to be about 0.56 min(-1) (R(2) = 0.974). Furthermore, the as-prepared catalyst can be easily recovered and reused for 8 times, which didn't show much decrease of the catalytic capability.

  16. Synthesis of Self-Assembled Multifunctional Nanocomposite Catalysts with Highly Stabilized Reactivity and Magnetic Recyclability

    NASA Astrophysics Data System (ADS)

    Yu, Xu; Cheng, Gong; Zheng, Si-Yang

    2016-05-01

    In this paper, a multifunctional Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite catalyst with highly stabilized reactivity and magnetic recyclability was synthesized by a self-assembled method. The magnetic Fe3O4 nanoparticles were coated with a thin layer of the SiO2 to obtain a negatively charged surface. Then positively charged poly(ethyleneimine) polymer (PEI) was self-assembled onto the Fe3O4@SiO2 by electrostatic interaction. Next, negatively charged glutathione capped gold nanoparticles (GSH-AuNPs) were electrostatically self-assembled onto the Fe3O4@SiO2@PEI. After that, silver was grown on the surface of the nanocomposite due to the reduction of the dopamine in the alkaline solution. An about 5 nm thick layer of polydopamine (PDA) was observed to form the Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was carefully characterized by the SEM, TEM, FT-IR, XRD and so on. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite shows a high saturation magnetization (Ms) of 48.9 emu/g, which allows it to be attracted rapidly to a magnet. The Fe3O4@SiO2@PEI-Au/Ag@PDA nanocomposite was used to catalyze the reduction of p-nitrophenol (4-NP) to p-aminophenol (4-AP) as a model system. The reaction kinetic constant k was measured to be about 0.56 min‑1 (R2 = 0.974). Furthermore, the as-prepared catalyst can be easily recovered and reused for 8 times, which didn’t show much decrease of the catalytic capability.

  17. Synthesis and reactivity of cyclometalated triamidophosphine complexes of niobium and tantalum.

    PubMed

    Sietzen, Malte; Wadepohl, Hubert; Ballmann, Joachim

    2015-04-20

    The triamidophosphine protioligand 1 reacts with the homoleptic pentakis(dimethylamido) precursors of niobium and tantalum [M(NMe2)5, where M = Nb, Ta] to form cyclometalated complexes of the type [N2PCN-κ(5)-N,N,P,C,N]M(NMe2) (2-M). Apart from the three amido donors, one benzylic position of the ligand backbone is deprotonated over the course of this reaction, resulting in the formation of a new M-C bond. As a consequence, a metallaziridine substructure is formed, and the triamidophosphine moiety thus serves as a tetraanionic pentadentate ligand. The dimethylamido complexes 2-M can be converted into the corresponding triflates [N2PCN-κ(5)-N,N,P,C,N]M(OTf) (3-M) and alkyl complexes [N2PCN-κ(5)-N,N,P,C,N]M(CH2SiMe3) (4-M) by treatment with triethylsilyl triflate (Et3SiO3SCF3) followed by (trimethylsilyl)methyllithium (LiCH2SiMe3). The alkyl complexes exhibit interesting reactivities, including a second cyclometalative backbone activation affording the trimethylphosphine-stabilized complexes [NP(CN)2-κ(6)-N,P,C,N,C,N]M(PMe3) (5-M). In the case of tantalum, the formation of a dinuclear hydrido complex (6) is observed upon hydrogenation of 4-Ta. In the case of niobium, the metallaziridine substructure in 4-Nb is prone to ring opening via protonation with triphenylsilylamine (Ph3SiNH2), resulting in formation of the corresponding imido complex [PN3-κ(4)-P,N,N,N]Nb=NSiPh3 (7).

  18. Synthesis of ferrocene-labeled steroids via copper-catalyzed azide-alkyne cycloaddition. Reactivity difference between 2β-, 6β- and 16β-azido-androstanes.

    PubMed

    Fehér, Klaudia; Balogh, János; Csók, Zsolt; Kégl, Tamás; Kollár, László; Skoda-Földes, Rita

    2012-06-01

    Copper-catalyzed cycloaddition of steroidal azides and ferrocenyl-alkynes were found to be an efficient methodology for the synthesis of ferrocene-labeled steroids. At the same time, a great difference between the reactivity of 2β- or 16β-azido-androstanes and a sterically hindered 6β-azido steroid toward both ferrocenyl-alkynes and simple alkynes, such as phenylacetylene, 1-octyne, propargyl acetate and methyl propiolate, was observed. Copyright © 2012 Elsevier Inc. All rights reserved.

  19. The Synthesis, Characterization and Reactivity of a Series of Ruthenium N-triphosPh Complexes

    PubMed Central

    Phanopoulos, Andreas; Long, Nicholas; Miller, Philip

    2015-01-01

    Herein we report the synthesis of a tridentate phosphine ligand N(CH2PPh2)3 (N-triphosPh) (1) via a phosphorus based Mannich reaction of the hydroxylmethylene phosphine precursor with ammonia in methanol under a nitrogen atmosphere. The N-triphosPh ligand precipitates from the solution after approximately 1 hr of reflux and can be isolated analytically pure via simple cannula filtration procedure under nitrogen. Reaction of the N-triphosPh ligand with [Ru3(CO)12] under reflux affords a deep red solution that show evolution of CO gas on ligand complexation. Orange crystals of the complex [Ru(CO)2{N(CH2PPh2)3}-κ3P] (2) were isolated on cooling to RT. The 31P{1H} NMR spectrum showed a characteristic single peak at lower frequency compared to the free ligand. Reaction of a toluene solution of complex 2 with oxygen resulted in the instantaneous precipitation of the carbonate complex [Ru(CO3)(CO){N(CH2PPh2)3}-κ3P] (3) as an air stable orange solid. Subsequent hydrogenation of 3 under 15 bar of hydrogen in a high-pressure reactor gave the dihydride complex [RuH2(CO){N(CH2PPh2)3}-κ3P] (4), which was fully characterized by X-ray crystallography and NMR spectroscopy. Complexes 3 and 4 are potentially useful catalyst precursors for a range of hydrogenation reactions, including biomass-derived products such as levulinic acid (LA). Complex 4 was found to cleanly react with LA in the presence of the proton source additive NH4PF6 to give [Ru(CO){N(CH2PPh2)3}-κ3P{CH3CO(CH2)2CO2H}-κ2O](PF6) (6). PMID:25938678

  20. Synthesis and Functions of Ag2S Nanostructures

    NASA Astrophysics Data System (ADS)

    Cui, Chunyan; Li, Xiaoru; Liu, Jixian; Hou, Yongchao; Zhao, Yuqing; Zhong, Guocheng

    2015-11-01

    The paper presents a review about synthesis and applications of Ag2S nanostructures. As the modern photoelectric and biological materials, Ag2S nanomaterials are potentially useful for both structure and function purposes. Ag2S is a direction narrow band gap semiconductor with special properties. Ag2S nanostructures have been widely researched in chemistry and biochemistry fields because of their unusual optical, electrical, and mechanical properties. It can also be used in many fields, such as photovoltaic cells and infrared detector. In the past few years, Ag2S nanostructures have been synthesized by various methods. The article mainly discusses the four types of preparation methods. Moreover, this article shows a detailed review on the new properties, fabrication, and applications of Ag2S nanocrystals.

  1. Point-spread function synthesis in scanning holographic microscopy

    PubMed Central

    Indebetouw, Guy; Zhong, Wenwei; Chamberlin-Long, David

    2006-01-01

    Scanning holographic microscopy is a two-pupil synthesis method allowing the capture of single-sideband inline holograms of noncoherent (e.g., fluorescent) three-dimensional specimens in a single two-dimensional scan. The flexibility offered by the two-pupil method in synthesizing unusual point-spread functions is discussed. We illustrate and compare three examples of holographic recording, using computer simulations. The first example is the classical hologram in which each object point is encoded as a spherical wave. The second example uses pupils with spherical phase distributions having opposite curvatures, leading to reconstructed images with a resolution limit that is half that of the objective. In the third example, axicon pupils are used to obtain axially sectioned images. PMID:16783435

  2. Synthesis, structural and conformational properties, and gas phase reactivity of 1,4-dihydropyridine ester and ketone derivatives.

    PubMed

    Giorgi, Gianluca; Adamo, Mauro F A; Ponticelli, Fabio; Ventura, Antonio

    2010-12-07

    A new series of 4-aryl-2,6-dimethyl-1,4-dihydropyridines, characterized by ester or ketone functions at positions 3 and 5, has been synthesized. Structural and conformational properties, concerning the dihydropyridine ring and the orientation (synplanar/antiperiplanar) of the substituents have been investigated in their crystal structure and in solution by nuclear magnetic resonance. Evaluation of intermolecular and hydrogen bonding interactions as well as packing features, have been also carried out, evidencing interesting packing motifs. Their gas phase reactivity, as protonated and deprotonated molecules, has been investigated by electrospray ionization, high resolution and collision-induced dissociation multiple stage mass spectrometry. Deydrogenation reactions have been observed as a function of the capillary voltage.

  3. Gender differences in the association between C-reactive protein, lung function impairment, and COPD

    PubMed Central

    Ólafsdóttir, Inga Sif; Gíslason, Thórarinn; Thjóđleifsson, Bjarni; Ólafsson, Ísleifur; Gíslason, Davíd; Jõgi, Rain; Janson, Christer

    2007-01-01

    Individuals with COPD have systemic inflammation that can be assessed by measuring C-reactive protein (CRP). In this paper we evaluated whether CRP is related to COPD, lung function and rate of lung function decline. We included 1237 randomly selected subjects (mean age 42, range 28–56 years) from three centers in the European Community Respiratory Health Survey: Reykjavik, Uppsala and Tartu. CRP was measured at the end of the follow-up (mean 8.3 years) and the values were divided into 4 quartiles. Fifty-three non-asthmatic subjects fulfilled spirometric criteria for COPD (FEV1/FVC < 70%). COPD occurred more often in the 4th CRP quartile (OR (95% CI) 3.21 (1.13–9.08)) after adjustment for age, gender, body weight and smoking. High CRP levels were related to lower FEV1 values in both men (−437 (−596, −279) mL) and women (−144 (−243, −44) mL). The negative association between CRP and FEV1 was significantly larger in men than women (p = 0.04). The decline in FEV1 was larger (16 (5, 27) mL) in men with high CRP levels whereas no significant association between CRP and FEV1 decline was found in women. Higher CRP values are significantly associated with COPD and lower lung function in men and women. In men higher CRP values are related to a larger decline in FEV1. PMID:18268938

  4. Organic functional group transformations in water at elevated temperature and pressure: Reversibility, reactivity, and mechanisms

    NASA Astrophysics Data System (ADS)

    Shipp, Jessie; Gould, Ian R.; Herckes, Pierre; Shock, Everett L.; Williams, Lynda B.; Hartnett, Hilairy E.

    2013-03-01

    Many transformation reactions involving hydrocarbons occur in the presence of H2O in hydrothermal systems and deep sedimentary systems. We investigate these reactions using laboratory-based organic chemistry experiments at high temperature and pressure (300 °C and 100 MPa). Organic functional group transformation reactions using model organic compounds based on cyclohexane with one or two methyl groups provided regio- and stereochemical markers that yield information about reversibility and reaction mechanisms. We found rapidly reversible interconversion between alkanes, alkenes, dienes, alcohols, ketones, and enones. The alkane-to-ketone reactions were not only completely reversible, but also exhibited such extensive reversibility that any of the functional groups along the reaction path (alcohol, ketone, and even the diene) could be used as the reactant and form all the other groups as products. There was also a propensity for these ring-based structures to dehydrogenate; presumably from the alkene, through a diene, to an aromatic ring. The product suites provide strong evidence that water behaved as a reactant and the various functional groups showed differing degrees of reactivity. Mechanistically-revealing products indicated reaction mechanisms that involve carbon-centered cation intermediates. This work therefore demonstrates that a wide range of organic compound types can be generated by abiotic reactions at hydrothermal conditions.

  5. Promotion of behavior and neuronal function by reactive oxygen species in C. elegans

    PubMed Central

    Li, Guang; Gong, Jianke; Lei, Haoyun; Liu, Jianfeng; Xu, X. Z. Shawn

    2016-01-01

    Reactive oxygen species (ROS) are well known to elicit a plethora of detrimental effects on cellular functions by causing damages to proteins, lipids and nucleic acids. Neurons are particularly vulnerable to ROS, and nearly all forms of neurodegenerative diseases are associated with oxidative stress. Here, we report the surprising finding that exposing C. elegans to low doses of H2O2 promotes, rather than compromises, sensory behavior and the function of sensory neurons such as ASH. This beneficial effect of H2O2 is mediated by an evolutionarily conserved peroxiredoxin-p38/MAPK signaling cascade. We further show that p38/MAPK signals to AKT and the TRPV channel OSM-9, a sensory channel in ASH neurons. AKT phosphorylates OSM-9, and such phosphorylation is required for H2O2-induced potentiation of sensory behavior and ASH neuron function. Our results uncover a beneficial effect of ROS on neurons, revealing unexpected complexity of the action of oxidative stressors in the nervous system. PMID:27824033

  6. Synthesis, characterization, and controlled assembly of functional nanostructures

    NASA Astrophysics Data System (ADS)

    Patete, Jonathan M.

    Nanomaterials represent a particularly interesting class of materials for research, as they bridge the gap between bulk materials and atomic or molecular structures, and often exhibit both novel chemical and physical properties. These properties may be altered not only by the chemical composition of the material but also by the size and shape of the nanoparticle. More specifically, the inherent anisotropy of one-dimensional nanostructures renders them as particularly efficient for electron transport applications. These materials are also highly sought after, because their distinctive shape allows for facile incorporation into functional device configurations. My graduate research has spanned several stages of nanotechnology from the synthesis and characterization of one-dimensional metal oxide nanostructures to the assembly of metal nanoparticles for practical device engineering. In particular, I have investigated the effect of the nanoscale size regime on the electronic, magnetic, and optical properties of as-prepared nanowires composed of hexagonal yttrium manganese oxide and olivine lithium iron phosphate. As a multiferroic material, h-YMnO3 is predominately sought after for applications in data storage devices. Alternatively, nanoscale LiFePO4 has shown a lot of promise as a cathode material in advanced lithium ion battery systems. The synthesis of both materials was achieved through template-directed methods, thereby allowing for precise control over the size and morphology of the as-obtained product. Finally, purposeful, directed methods for controlling the deposition pattern of metallic nanoparticles on a two-dimensional surface will be presented, and their viability as functional optical sensors will be explored.

  7. Combining bifunctional chelator with (3 + 2)-cycloaddition approaches: synthesis of dual-function technetium complexes.

    PubMed

    Braband, Henrik; Imstepf, Sebastian; Benz, Michael; Spingler, Bernhard; Alberto, Roger

    2012-04-02

    A new concept for the synthesis of dual-functionalized technetium (Tc) compounds is presented, on the basis of the reactivity of fac-{Tc(VII)O(3)}(+) complexes. The concept combines the "classical" bifunctional chelator (BFC) approach with the new ligand centered labeling strategy of fac-{TcO(3)}(+) complexes with alkenes ((3 + 2)-cycloaddition approach). To evidence this concept, fac-{(99)TcO(3)}(+) model complexes containing functionalized 1,4,7-triazacyclononane (tacn) derivatives N-benzyl-2-(1,4,7-triazonan-1-yl)acetamide (tacn-ba) and 2,2',2″-(1,4,7-triazonane-1,4,7-triyl)triacetic acid (nota·3H) were synthesized and characterized. Whereas [(99)TcO(3)(tacn-ba)](+) [2](+) can be synthesized following a established oxidation procedure starting from the Tc(V) complex [(99)TcO(glyc)(tacn-ba)](+) [1](+), a new synthetic pathway for the synthesis of [(99)TcO(3)(nota)](2-) [5](2-) had to be developed, starting from [(99)Tc(nota·3H)(CO)(3)](+) [4](+) and using sodium perborate tetrahydrate (NaBO(3)·4H(2)O) as oxidizing reagent. While [(99)TcO(3)(nota)](2-) [5](2-) is a very attractive candidate for the development of trisubstituted novel multifunctional radioprobes, (3 + 2)-cycloaddition reactions of [(99)TcO(3)(tacn-ba)](+) [2](+) with 4-vinylbenzenesulfonate (styrene-SO(3)(-)) demonstrated the suitability of monosubstituted tacn derivatives for the new mixed "BFC-(3 + 2)-cycloaddition" approach. Kinetic studies of this reaction lead to the conclusion that the alteration of the electronic structure of the nitrogen donors by, e.g., alkylation can be used to tune the rate of the (3 + 2)-cycloaddition.

  8. Synthesis, characterization, and reactivity studies of heterodinuclear complexes modeling active sites in purple acid phospatases.

    PubMed

    Jarenmark, Martin; Haukka, Matti; Demeshko, Serhiy; Tuczek, Felix; Zuppiroli, Luca; Meyer, Franc; Nordlander, Ebbe

    2011-05-02

    the reactivities are different for different complexes and generally show strong pH dependence.

  9. Synthesis, structural characterization, and reactivity studies of 5-CF3SO3-B10H13.

    PubMed

    Berkeley, Emily R; Ewing, William C; Carroll, Patrick J; Sneddon, Larry G

    2014-05-19

    In contrast to previous reactions carried out in cyclopentane solvent at room temperature that produced 6-TfO-B10H13 (TfO = CF3SO3), the reaction of closo-B10H10(2-) with a large excess of trifluoromethanesulfonic acid in the ionic liquid 1-butyl-3-methylimidazolium trifluoromethanesulfonate (bmimOTf) gave exclusively the previously unknown 5-TfO-B10H13 isomer. Experimental and computational studies demonstrated that the difference in the products of the two reactions is a result of 6-TfO-B10H13 isomerizing to 5-TfO-B10H13 above room temperature in bmimOTf solutions. Reactivity studies showed that 5-TfO-B10H13: (1) is deprotonated by reaction with 1,8-bis(dimethylamino)naphthalene to form the 5-TfO-B10H12(1-) anion; (2) reacts with alcohols to produce 6-RO-B10H13 boryl ethers (R = Me and 4-CH3O-C6H4); (3) undergoes olefin-hydroboration reactions to form 5-TfO-6,9-R2-B10H11 derivatives; and (4) forms a 5-TfO-6,9-(Me2S)2-B10H11 adduct at its Lewis acidic 6,9-borons upon reaction with dimethylsulfide. The 5-TfO-6,9-(Me2S)2-B10H11 adduct was also found to undergo alkyne-insertion reactions to form a range of previously unreported triflate-substituted 4-TfO-ortho-carboranes (1-R-4-TfO-1,2-C2B10H10) and reactions with triethylamine or ammonia to form the first TfO-substituted decaborate [R3NH(+)]2[2-TfO-B10H9(2-)], and [R3NH(+)]2[1-TfO-B10H9(2-)] (R = H, Et) salts.

  10. Synthesis, characterization, and reactivity of Ti(IV)-monosubstituted Keggin polyoxometalates.

    PubMed

    Kholdeeva, Oxana A; Trubitsina, Tatiana A; Maksimov, Gennadii M; Golovin, Anatolii V; Maksimovskaya, Raisa I

    2005-03-07

    Ti(IV)-monosubstituted Keggin-type polyoxometalates (Ti-POMs), mu-oxo dimer [Bu4N]8[(PTiW11O39)2O] (1), and three monomers [Bu4N]4[PTi(L)W11O39], where L = OH (2), OMe (3), and OAr (4, ArOH = 2,3,6-trimethylphenol (TMP)), have been prepared starting from mu-hydroxo dimer [Bu4N]7[(PTiW11O39)2OH] (5) or heteropolyacid H5PW11TiO40 or both. The compounds have been characterized by elemental analysis, IR, UV-vis, and multinuclear (31P, 1H, 183W) NMR. The interaction of 1 and 3-5 with H2O in MeCN produces 2. The hydrolysis constants, estimated from 31P and 1H NMR data, are 0.006 and 0.04 for 1 and 3, respectively. Studies by 31P NMR, IR, potentiometric titration, and cyclic voltammetry revealed that 1-3 and 5 afford the same protonated titanium peroxo complex [Bu4N]4[HPTi(O2)W11O39] (I) upon interaction with aqueous H2O2 in MeCN. The rates of formation of I correlate with the rates of hydrolysis of the Ti-POMs and follow the order of 5 > 1 > 3. A two-step mechanism of the reaction of Ti-POMs with H2O2, which involves hydrolysis of the Ti-L bonds to yield 2 followed by fast interaction of 2 with hydrogen peroxide producing I, is suggested. The equilibrium constant for the reaction of 2 with H2O2 to yield I and H2O, estimated using 31P NMR, is 10. The interaction of the Ti-POMs with TMP follows the trends similar to their interaction with H2O) and requires preliminary hydrolysis of the Ti-L bonds. All of the Ti-POMs catalyze the oxidation of TMP with H2O2 in MeCN to give 2,3,5-trimethyl-p-benzoquinone and 2,2',3,3',5,5'-hexamethyl-4,4'-biphenol. The product distribution is similar for all of the Ti-POMs. The catalytic activities of the Ti-POMs correlate with the rates of formation of I and follow the order of 2 > 5 > 1 > 3. The findings lay a basis for a better understanding of the nature of the reactivity of titanium in Ti-catalyzed oxidations.

  11. Reactive Oxygen Species Prevent Imiquimod-Induced Psoriatic Dermatitis through Enhancing Regulatory T Cell Function

    PubMed Central

    Choi, Eun-Jeong; Hong, Min-Pyo; Kie, Jeong-Hae; Lim, Woosung; Lee, Hyeon Kook; Moon, Byung-In; Seoh, Ju-Young

    2014-01-01

    Psoriasis is a chronic inflammatory skin disease resulting from immune dysregulation. Regulatory T cells (Tregs) are important in the prevention of psoriasis. Traditionally, reactive oxygen species (ROS) are known to be implicated in the progression of inflammatory diseases, including psoriasis, but many recent studies suggested the protective role of ROS in immune-mediated diseases. In particular, severe cases of psoriasis vulgaris have been reported to be successfully treated by hyperbaric oxygen therapy (HBOT), which raises tissue level of ROS. Also it was reported that Treg function was closely associated with ROS level. However, it has been only investigated in lowered levels of ROS so far. Thus, in this study, to clarify the relationship between ROS level and Treg function, as well as their role in the pathogenesis of psoriasis, we investigated imiquimod-induced psoriatic dermatitis (PD) in association with Treg function both in elevated and lowered levels of ROS by using knockout mice, such as glutathione peroxidase-1−/− and neutrophil cytosolic factor-1−/− mice, as well as by using HBOT or chemicals, such as 2,3-dimethoxy-1,4-naphthoquinone and N-acetylcysteine. The results consistently showed Tregs were hyperfunctional in elevated levels of ROS, whereas hypofunctional in lowered levels of ROS. In addition, imiquimod-induced PD was attenuated in elevated levels of ROS, whereas aggravated in lowered levels of ROS. For the molecular mechanism that may link ROS level and Treg function, we investigated the expression of an immunoregulatory enzyme, indoleamine 2,3-dioxygenase (IDO) which is induced by ROS, in PD lesions. Taken together, it was implied that appropriately elevated levels of ROS might prevent psoriasis through enhancing IDO expression and Treg function. PMID:24608112

  12. Cerebral reactivity in migraine patients measured with functional near-infrared spectroscopy.

    PubMed

    Pourshoghi, Ahmadreza; Danesh, Arash; Tabby, David Stuart; Grothusen, John; Pourrezaei, Kambiz

    2015-12-08

    There are two major theories describing the pathophysiology of migraines. Vascular theory explains that migraines resulted from vasodilation of meningeal vessels irritating the trigeminal nerves and causing pain. More recently, a neural theory of migraine has been proposed, which suggests that cortical hyperexcitability leads to cortical spreading depression (CSD) causing migraine-like symptoms. Chronic migraine requires prophylactic therapy. When oral agents fail, there are several intravenous agents that can be used. Understanding underlying causes of migraine pain would help to improve efficacy of migraine medications by changing their mechanism of action. Yet to date no study has been made to investigate the link between vascular changes in response to medications for migraine versus pain improvements. Functional near-infrared spectroscopy (NIRS) has been used as an inexpensive, rapid, non-invasive and safe technique to monitor cerebrovascular dynamics. In this study, a multi-distance near-infrared spectroscopy device has been used to investigate the cortical vascular reactivity of migraine patients in response to drug infusions and its possible correlation with changes in pain experienced. We used the NIRS on 41 chronic migraine patients receiving three medications: magnesium sulfate, valproate sodium, and dihydroergotamine (DHE). Patients rated their pain on a 1-10 numerical scale before and after the infusion. No significant differences were observed between the medication effects on vascular activity from near channels measuring skin vascularity. However, far channels--indicating cortical vascular activity--showed significant differences in both oxyhemoglobin and total hemoglobin between medications. DHE is a vasoconstrictor and decreased cortical blood volume in our experiment. Magnesium sulfate has a short-lived vasodilatory effect and increased cortical blood volume in our experiment. Valproate sodium had no significant effect on blood volume

  13. Template-mediated synthesis and bio-functionalization of flexible lignin-based nanotubes and nanowires

    NASA Astrophysics Data System (ADS)

    Caicedo, Hector M.; Dempere, Luisa A.; Vermerris, Wilfred

    2012-03-01

    Limitations of cylindrical carbon nanotubes based on the buckminsterfullerene structure as delivery vehicles for therapeutic agents include their chemical inertness, sharp edges and toxicological concerns. As an alternative, we have developed lignin-based nanotubes synthesized in a sacrificial template of commercially available alumina membranes. Lignin is a complex phenolic plant cell wall polymer that is generated as a waste product from paper mills and biorefineries that process lignocellulosic biomass into fuels and chemicals. We covalently linked isolated lignin to the inner walls of activated alumina membranes and then added layers of dehydrogenation polymer onto this base layer via a peroxidase-catalyzed reaction. By using phenolic monomers displaying different reactivities, we were able to change the thickness of the polymer layer deposited within the pores, resulting in the synthesis of nanotubes with a wall thickness of approximately 15 nm or nanowires with a nominal diameter of 200 nm. These novel nanotubes are flexible and can be bio-functionalized easily and specifically, as shown by in vitro assays with biotin and Concanavalin A. Together with their intrinsic optical properties, which can also be varied as a function of their chemical composition, these lignin-based nanotubes are expected to enable a variety of new applications including as delivery systems that can be easily localized and imaged after uptake by living cells.

  14. Metal complexes with oxygen-functionalized NHC ligands: synthesis and applications.

    PubMed

    Hameury, Sophie; de Frémont, Pierre; Braunstein, Pierre

    2017-02-06

    Ligand design has met with considerable success with both categories of hybrid ligands, which are characterized by chemically different donor groups, and of N-heterocyclic carbenes (NHCs). Their spectacular development and diversity are attracting worldwide interest and offers almost unlimited diversity and potential in e.g. coordination/organometallic main group and transition metal chemistry, catalysis, medicinal chemistry and materials science. This review aims at providing a comprehensive update on a specific class of ligands that has enjoyed much attention in the past few years, at the intersection between the two categories mentioned above, that of hybrid NHC ligands in which the functionality associated with the carbene donor is of the oxygen-donor type. For each type of oxygen-donor present in such chelating (Section 1) or bridging (Section 2) hybrid ligands, we will examine the synthesis, structures and reactivity of their metal complexes and their applications, with a special focus on homogeneous catalysis (Section 3). Thus, hydrogenation, C-H bond activation, C-C, C-N, C-O bond formation, hydrolysis of silanes, oligomerization, polymerization, metathesis, hydrosilylation, C-C bond cleavage, acceptorless dehydrogenation, dehalogenation/hydrogen transfer, oxidation and reduction reactions will be successively presented in a tabular manner, to facilitate an overview and a rapid identification of the relevant publications describing which metals associated with a given oxygen functionality are most suitable. The literature coverage includes the year 2015.

  15. Template-mediated synthesis and bio-functionalization of flexible lignin-based nanotubes and nanowires.

    PubMed

    Caicedo, Hector M; Dempere, Luisa A; Vermerris, Wilfred

    2012-03-16

    Limitations of cylindrical carbon nanotubes based on the buckminsterfullerene structure as delivery vehicles for therapeutic agents include their chemical inertness, sharp edges and toxicological concerns. As an alternative, we have developed lignin-based nanotubes synthesized in a sacrificial template of commercially available alumina membranes. Lignin is a complex phenolic plant cell wall polymer that is generated as a waste product from paper mills and biorefineries that process lignocellulosic biomass into fuels and chemicals. We covalently linked isolated lignin to the inner walls of activated alumina membranes and then added layers of dehydrogenation polymer onto this base layer via a peroxidase-catalyzed reaction. By using phenolic monomers displaying different reactivities, we were able to change the thickness of the polymer layer deposited within the pores, resulting in the synthesis of nanotubes with a wall thickness of approximately 15 nm or nanowires with a nominal diameter of 200 nm. These novel nanotubes are flexible and can be bio-functionalized easily and specifically, as shown by in vitro assays with biotin and Concanavalin A. Together with their intrinsic optical properties, which can also be varied as a function of their chemical composition, these lignin-based nanotubes are expected to enable a variety of new applications including as delivery systems that can be easily localized and imaged after uptake by living cells.

  16. Synthesis and Reactivity of (18)F-Labeled α,α-Difluoro-α-(aryloxy)acetic Acids.

    PubMed

    Khotavivattana, Tanatorn; Calderwood, Samuel; Verhoog, Stefan; Pfeifer, Lukas; Preshlock, Sean; Vasdev, Neil; Collier, Thomas L; Gouverneur, Véronique

    2017-02-03

    In this work, we describe the (18)F-labeling of α,α-difluoro-α-(aryloxy)acetic acid derivatives and demonstrate that these building blocks are amenable to post-(18)F-fluorination functionalization. Protodecarboxylation offers a new entry to (18)F-difluoromethoxyarene, and the value of this approach is further demonstrated with coupling processes leading to representative (18)F-labeled TRPV1 inhibitors and TRPV1 antagonists.

  17. Synthesis, Structure, and Reactivity of Co(II) and Ni(II) PCP Pincer Borohydride Complexes

    PubMed Central

    2015-01-01

    The 15e square-planar complexes [Co(PCPMe-iPr)Cl] (2a) and [Co(PCP-tBu)Cl] (2b), respectively, react readily with NaBH4 to afford complexes [Co(PCPMe-iPr)(η2-BH4)] (4a) and [Co(PCP-tBu)(η2-BH4)] (4b) in high yields, as confirmed by IR spectroscopy, X-ray crystallography, and elemental analysis. The borohydride ligand is symmetrically bound to the cobalt center in η2-fashion. These compounds are paramagnetic with effective magnetic moments of 2.0(1) and 2.1(1) μB consistent with a d7 low-spin system corresponding to one unpaired electron. None of these complexes reacted with CO2 to give formate complexes. For structural and reactivity comparisons, we prepared the analogous Ni(II) borohydride complex [Ni(PCPMe-iPr)(η2-BH4)] (5) via two different synthetic routes. One utilizes [Ni(PCPMe-iPr)Cl] (3) and NaBH4, the second one makes use of the hydride complex [Ni(PCPMe-iPr)H] (6) and BH3·THF. In both cases, 5 is obtained in high yields. In contrast to 4a and 4b, the borohydride ligand is asymmetrically bound to the nickel center but still in an η2-mode. [Ni(PCPMe-iPr)(η2-BH4)] (5) loses readily BH3 at elevated temperatures in the presence of NEt3 to form 6. Complexes 5 and 6 are both diamagnetic and were characterized by a combination of 1H, 13C{1H}, and 31P{1H} NMR, IR spectroscopy, and elemental analysis. Additionally, the structure of these compounds was established by X-ray crystallography. Complexes 5 and 6 react with CO2 to give the formate complex [Ni(PCPMe-iPr)(OC(C=O)H] (7). The extrusion of BH3 from [Co(PCPMe-iPr)(η2-BH4)] (4a) and [Ni(PCPMe-iPr)(η2-BH4)] (5) with the aid of NH3 to yield the respective hydride complexes [Co(PCPMe-iPr)H] and [Ni(PCPMe-iPr)H] (6) and BH3NH3 was investigated by DFT calculations showing that formation of the Ni hydride is thermodynamically favorable, whereas the formation of the Co(II) hydride, in agreement with the experiment, is unfavorable. The electronic structures and the bonding of the borohydride ligand in [Co

  18. Synthesis, Structure, and Reactivity of Co(II) and Ni(II) PCP Pincer Borohydride Complexes.

    PubMed

    Murugesan, Sathiyamoorthy; Stöger, Berthold; Weil, Matthias; Veiros, Luis F; Kirchner, Karl

    2015-04-13

    The 15e square-planar complexes [Co(PCP(Me)-iPr)Cl] (2a) and [Co(PCP-tBu)Cl] (2b), respectively, react readily with NaBH4 to afford complexes [Co(PCP(Me)-iPr)(η(2)-BH4)] (4a) and [Co(PCP-tBu)(η(2)-BH4)] (4b) in high yields, as confirmed by IR spectroscopy, X-ray crystallography, and elemental analysis. The borohydride ligand is symmetrically bound to the cobalt center in η(2)-fashion. These compounds are paramagnetic with effective magnetic moments of 2.0(1) and 2.1(1) μB consistent with a d(7) low-spin system corresponding to one unpaired electron. None of these complexes reacted with CO2 to give formate complexes. For structural and reactivity comparisons, we prepared the analogous Ni(II) borohydride complex [Ni(PCP(Me)-iPr)(η(2)-BH4)] (5) via two different synthetic routes. One utilizes [Ni(PCP(Me)-iPr)Cl] (3) and NaBH4, the second one makes use of the hydride complex [Ni(PCP(Me)-iPr)H] (6) and BH3·THF. In both cases, 5 is obtained in high yields. In contrast to 4a and 4b, the borohydride ligand is asymmetrically bound to the nickel center but still in an η(2)-mode. [Ni(PCP(Me)-iPr)(η(2)-BH4)] (5) loses readily BH3 at elevated temperatures in the presence of NEt3 to form 6. Complexes 5 and 6 are both diamagnetic and were characterized by a combination of (1)H, (13)C{(1)H}, and (31)P{(1)H} NMR, IR spectroscopy, and elemental analysis. Additionally, the structure of these compounds was established by X-ray crystallography. Complexes 5 and 6 react with CO2 to give the formate complex [Ni(PCP(Me)-iPr)(OC(C=O)H] (7). The extrusion of BH3 from [Co(PCP(Me)-iPr)(η(2)-BH4)] (4a) and [Ni(PCP(Me)-iPr)(η(2)-BH4)] (5) with the aid of NH3 to yield the respective hydride complexes [Co(PCP(Me)-iPr)H] and [Ni(PCP(Me)-iPr)H] (6) and BH3NH3 was investigated by DFT calculations showing that formation of the Ni hydride is thermodynamically favorable, whereas the formation of the Co(II) hydride, in agreement with the experiment, is unfavorable. The electronic structures and

  19. Superhydrophobic Thin Films Fabricated by Reactive Layer-by-Layer Assembly of Azlactone-Functionalized Polymers

    PubMed Central

    Buck, Maren E.; Schwartz, Sarina C.

    2010-01-01

    We report an approach to the fabrication of superhydrophobic thin films that is based on the ‘reactive’ layer-by-layer assembly of azlactone-containing polymer multilayers. We demonstrate that films fabricated from alternating layers of the azlactone functionalized polymer poly(2-vinyl-4,4-dimethylazlactone) (PVDMA) and poly(ethyleneimine) (PEI) exhibit micro- and nanoscale surface features that result in water contact angles in excess of 150º. Our results reveal that the formation of these surface features is (i) dependent upon film thickness (i.e., the number of layers of PEI and PVDMA deposited) and (ii) that it is influenced strongly by the presence (or absence) of cyclic azlactone-functionalized oligomers that can form upon storage of the 2-vinyl-4,4-dimethylazlactone (VDMA) used to synthesize PVDMA. For example, films fabricated using polymers synthesized in the presence of these oligomers exhibited rough, textured surfaces and superhydrophobic behavior (i.e., advancing contact angles in excess of 150º). In contrast, films fabricated from PVDMA polymerized in the absence of this oligomer (e.g., using freshly distilled monomer) were smooth and only moderately hydrophobic (i.e., advancing contact angles of ~75º). The addition of authentic, independently synthesized oligomer to samples of distilled VDMA at specified and controlled concentrations permitted reproducible fabrication of superhydrophobic thin films on the surfaces of a variety of different substrates. The surfaces of these films were demonstrated to be superhydrophobic immediately after fabrication, but they became hydrophilic after exposure to water for six days. Additional experiments demonstrated that it was possible to stabilize and prolong the superhydrophobic properties of these films (e.g., advancing contact angles in excess of 150° even after complete submersion in water for at least six weeks) by exploiting the reactivity of residual azlactones to functionalize the surfaces of the

  20. Synthesis of thiol-reactive lipopeptide adjuvants. Incorporation into liposomes and study of their mitogenic effect on mouse splenocytes.

    PubMed

    Roth, Audrey; Espuelas, Socorro; Thumann, Christine; Frisch, Benoît; Schuber, Francis

    2004-01-01

    Synthetic analogues of triacylated and diacylated lipopeptides derived from the N-terminal domain of respectively bacterial and mycoplasmal lipoproteins are highly potent immunoadjuvants when administered either in combination with protein antigens or covalently linked to small peptide epitopes. Because of their amphipathic properties, lipopeptides, such as S-[2,3-bis(palmitoyloxy)-(2RS)-propyl]-N-palmitoyl-(R)-cysteinyl-alanyl-glycine (Pam(3)CAG), can be conveniently incorporated into liposomes and serve as anchors for antigens that are linked to them. To design vaccination constructs based on synthetic peptides and liposomes as vectors. we have accordingly synthesized a series of lipopeptides that differ by the number (Pam(3)C vs Pam(2)C) and nature of the acyl chains (palmitoyl vs oleoyl) and by the presence at their C-terminus of thiol-reactive functions, such as maleimide or bromoacetyl. When incorporated into liposomes, these latter functionalized lipopeptides allow, in aqueous media, a well controlled chemoselective conjugation of HS-peptides to the surface of the vesicles. Using a BALB/c mice splenocyte proliferation assay ([(3)H]thymidine incorporation), we have measured the lymphocyte activation potency of the different lipopeptides. We found that, compared to their free (emulsified) forms, the liposomal lipopeptides were endowed with enhanced mitogenic activities; i.e., up to 2 orders of magnitude for Pam(3)CAG which was more potent than Pam(2)CAG. The impact of functionalization on the cellular activity of Pam(3)CAG was dependent on the thiol-reactive group introduced: whereas the bromoacetyl derivative retained its full activity, the presence of a maleimide group virtually abolished the lymphocyte activation of the lipopeptide. Finally, the substitution of saturated palmitoyl chains by unsaturated oleoyl chains was inhibitory. Thus, thiol-reactive Ol(3)CAG derivatives were the least active mitogens in our assay. Taken together, our findings are of

  1. Structural modeling of iron halogenases: synthesis and reactivity of halide-iron(IV)-oxo compounds.

    PubMed

    Planas, Oriol; Clémancey, Martin; Latour, Jean-Marc; Company, Anna; Costas, Miquel

    2014-09-25

    A structural synthetic model of the iron(IV)-oxo-halide active species of non-heme iron dependent halogenases is reported. Compounds with general formula [Fe(IV)(O)(X)(Pytacn)](+) (1-X, X = Cl, Br) have been prepared and characterized spectroscopically and chemically with regard to their oxidizing ability. 1-X performs hydrogen-atom abstraction of C-H bonds at reaction rates 2-3 times faster than the corresponding solvato dicationic species, thus modelling the first step in C-H functionalization taking place in natural halogenation.

  2. Molecular Differentiated Initiator Reactivity in the Synthesis of Poly(caprolactone)-Based Hydrophobic Homopolymer and Amphiphilic Core Corona Star Polymers.

    PubMed

    Deng, Eileen; Nguyen, Nam T; Hild, Frédéric; Hamilton, Ian E; Dimitrakis, Georgios; Kingman, Samuel W; Lau, Phei-Li; Irvine, Derek J

    2015-11-09

    Macromolecules that possess three-dimensional, branched molecular structures are of great interest because they exhibit significantly differentiated application performance compared to conventional linear (straight chain) polymers. This paper reports the synthesis of 3- and 4-arm star branched polymers via ring opening polymerisation (ROP) utilising multi-functional hydroxyl initiators and Sn(Oct)2 as precatalyst. The structures produced include mono-functional hydrophobic and multi-functional amphiphilic core corona stars. The characteristics of the synthetic process were shown to be principally dependent upon the physical/dielectric properties of the initiators used. ROP's using initiators that were more available to become directly involved with the Sn(Oct)₂ in the "in-situ" formation of the true catalytic species were observed to require shorter reaction times. Use of microwave heating (MWH) in homopolymer star synthesis reduced reaction times compared to conventional heating (CH) equivalents, this was attributed to an increased rate of "in-situ" catalyst formation. However, in amphiphilic core corona star formation, the MWH polymerisations exhibited slower propagation rates than CH equivalents. This was attributed to macro-structuring within the reaction medium, which reduced the potential for reaction. It was concluded that CH experiments were less affected by this macro-structuring because it was disrupted by the thermal currents/gradients caused by the conductive/convective heating mechanisms. These gradients are much reduced/absent with MWH because it selectively heats specific species simultaneously throughout the entire volume of the reaction medium. These partitioning problems were overcome by introducing additional quantities of the species that had been determined to selectively heat.

  3. Synthesis, Structure, and Reactivity ofbis(1,2,4-tri-t-butylcyclopentadienyl) Complexes of Cerium

    SciTech Connect

    Werkema, Evan L.

    2005-05-19

    The sterically demanding 1,2,4-tri-t-butylcyclopentadienylligand (1,2,4-(Me3C)3C5H2, hereafter Cp') has been used to preparemonomeric cerium metallocenes, Cp 2CeX (X = Cl, I, OSO2CF3), which areused to synthesize the benzyl, Cp'2CeCH2C6H5. The benzyl is a usefulstarting material for preparing other complexes in the Cp'2CeZ system (Z= BF4, F, NH2, C6H5, H). X-ray crystal structures of Cp'2CeOSO2CF3,Cp'2CeF, Cp'2CeCH2C6H5, and Cp'2CeH are presented. The benzyl slowlydecomposes in solution to toluene and a metallacycle,[Cp'][(Me3C)2C5H2(CMe2CH2)]Ce. The ring CMe3 groups of both themetallacycle and the hydride, Cp'2CeH, can be fully deuterated byprolonged exposure to C6D6, providing a useful labeling tool inmechanistic studies.The hydride activates C-F and/or C-H bonds influorobenzenes, C6HxF6-x , x = 0-5. The reactions are selective, with theselectivity depending on the presence of two fluorines ortho to thereaction site more than on the type of bond activated. Complexes of thetype Cp'2CeC6HxF5-x , x = 0-4, are formed as intermediates, which slowlydecompose in solution to Cp'2CeF and fluorobenzynes, C6HxF4-x, x = 0-4,which are trapped. The rate at which Cp'2CeC6HxF5-x complexes decomposeincreases as the number of fluorines decreases. Complexes with oneortho-fluorine decompose much faster than those with two ortho-fluorines.The metallacycle activates only C-H bonds in fluorobenzenes, permittingthe synthesis of specific Cp'2

  4. Loss of cystic fibrosis transmembrane conductance regulator function enhances activation of p38 and ERK MAPKs, increasing interleukin-6 synthesis in airway epithelial cells exposed to Pseudomonas aeruginosa.

    PubMed

    Bérubé, Julie; Roussel, Lucie; Nattagh, Leila; Rousseau, Simon

    2010-07-16

    In cystic fibrosis (CF), the absence of functional cystic fibrosis transmembrane conductance regulator (CFTR) translates into chronic bacterial infection, excessive inflammation, tissue damage, impaired lung function and eventual death. Understanding the mechanisms underlying this vicious circle of inflammation is important to design better therapies for CF. We found in CF lung biopsies increased immunoreactivity for p38 MAPK activity markers. Moreover, when compared with their non-CF counterpart, airway epithelial cells expressing the most common mutation in CF (CFTRDeltaF508) were more potent at inducing neutrophil chemotaxis through increased interleukin (IL)-6 synthesis when challenged with Pseudomonas aeruginosa diffusible material. We then discovered that in CFTRDeltaF508 cells, the p38 and ERK MAPKs are hyperactivated in response to P. aeruginosa diffusible material, leading to increased IL-6 mRNA expression and stability. Moreover, although TLR5 contributes to p38 MAPK activation upon P. aeruginosa challenge, it only played a weak role in IL-6 synthesis. Instead, we found that the production of reactive oxygen species is essential for IL-6 synthesis in response to P. aeruginosa diffusible material. Finally, we uncovered that in CFTRDeltaF508 cells, the extracellular glutathione levels are decreased, leading to a greater sensitivity to reactive oxygen species, providing an explanation for the hyperactivation of the p38 and ERK MAPKs and increased IL-6 synthesis. Taken together, our study has characterized a mechanism whereby the CFTRDeltaF508 mutation in airway epithelial cells contributes to increase inflammation of the airways.

  5. Synthesis of surface functionalized magnetic nanoparticles and their polymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Miner, M. J.; Morales, M. B.; Poddar, P.; Srikanth, H.; Skidmore, S. M.; Weller, T. M.

    2008-03-01

    Magnetic nanoparticles embedded in polymer matrices are good examples of functional nanostructures with excellent potential in applications such as tunable microwave devices, EMI shielding, flexible electronics etc. Control over the dispersion of the nanoparticle phase embedded in a polymer matrix is critical and often challenging. To achieve excellent dispersion, competition between polymer-polymer and polymer-particle interactions must be balanced to avoid clustering of particles in polymer nanocomposites. In earlier work, we had demonstrated the successful synthesis of 2μm thick spin coated nanocomposite PMMA films with Fe3O4 (mean size 15nm) nanoparticle inclusions exhibiting superparamagnetic behavior. In this work, we will present our attempts to achieve thicker films more suitable for microwave applications and a study of the role of surface functionalization of ferrite nanoparticles synthesized using co-precipitation and hydrothermal routes. Cross-sectional SEM and TEM studies as well as magnetic characterization using a Physical Property Measurement System will be presented and discussed. We will also report on the microwave response of these films using a coplanar waveguide fixture. Work at USF supported by NSF through a GOALI grant from NSF-DMII.

  6. Functionalized Gold Nanoparticles: Synthesis, Properties and Applications--A Review.

    PubMed

    Alex, Saji; Tiwari, Ashutosh

    2015-03-01

    The past few decades have witnessed significant advances in the development of functionalized gold nanoparticles for applications in various fields such as chemistry, biology, pharmacy and physics. Although it has been more than 150 years since they were first synthesized, extensive research has recently been undertaken to improve or modify gold nanoparticles, thereby opening up opportunities to enhance and optimize their potential and breadth of their applicability. Recently developed methods have allowed a precise control of gold nanoparticle size and the modification of gold nanoparticles with suitable protecting and functionalizing agents, facilitate their applications in different areas such as chemical and biological sensing, imaging and biomedical applications. This review focuses on the recent developments in various methods for the size and shape controlled synthesis of gold nanoparticles, understanding of different properties of gold nanoparticles and their applications in various fields. Particular attention is given to the chemical and biological sensing applications of gold nanoparticles and on the advances in the controlled ordering of gold nanoparticles for creating nanostructures for diverse applications.

  7. Synthesis and reactivity of cationic niobium and tantalum methyl complexes supported by imido and β-diketiminato ligands.

    PubMed

    Tomson, Neil C; Arnold, John; Bergman, Robert G

    2011-08-14

    The synthesis and reactivity of the cationic niobium and tantalum monomethyl complexes [(BDI)MeM(N(t)Bu)][X] (BDI = [Ar]NC(CH(3))CHC(CH(3))N[Ar], Ar = 2,6-(i)Pr(2)C(6)H(3); M = Nb, Ta; X = MeB(C(6)F(5))(3), B(C(6)F(5))(4)] was investigated. The cationic alkyl complexes failed to irreversibly bind CO but formed phosphine-trapped acyl complexes [(BDI)(R(3)PC(O)Me)M(N(t)Bu)][B(C(6)F(5))(4)] (R = Et, Cy) in the presence of a combination of trialkylphosphines and CO. Treatment of the monoalkyl cationic Nb complex with XylNC (Xyl = 2,6-Me(2)-C(6)H(3)) resulted in irreversible formation of the iminoacyl complex [(BDI)(XylN[double bond, length as m-dash]C(Me))Nb(N(t)Bu)][B(C(6)F(5))(4)], which did not bind phosphines but would add a methide group to the iminoacyl carbon to provide the known ketimine complex (BDI)(XylNCMe(2))Nb(N(t)Bu). Further stoichiometric chemistry explored i) migratory insertion reactions to form new alkoxide, amidinate, and ketimide complexes; ii) protonolysis reactions with Ph(3)SiOH to form thermally robust cationic siloxide complexes; and iii) catalytic high-density polyethylene formation mediated by the cationic Nb methyl complex. This journal is © The Royal Society of Chemistry 2011

  8. Reactive combinatorial synthesis and characterization of a gradient Ag-Ti oxide thin film with antibacterial properties.

    PubMed

    Unosson, Erik; Rodriguez, Daniel; Welch, Ken; Engqvist, Håkan

    2015-01-01

    The growing demand for orthopedic and dental implants has spurred researchers to develop multifunctional coatings, combining tissue integration with antibacterial features. A possible strategy to endow titanium (Ti) with antibacterial properties is by incorporating silver (Ag), but designing a structure with adequate Ag(+) release while maintaining biocompatibility has been shown difficult. To further explore the composition-structure-property relationships between Ag and Ti, and its effects against bacteria, this study utilized a combinatorial approach to manufacture and test a single sample containing a binary Ag-Ti oxide gradient. The sample, sputter-deposited in a reactive (O2) environment using a custom-built combinatorial physical vapor deposition system, was shown to be effective against Staphylococcus aureus with viability reductions ranging from 17 to above 99%, depending on the amount of Ag(+) released from its different parts. The Ag content along the gradient ranged from 35 to 62 wt.%, but it was found that structural properties such as varied porosity and degree of crystallinity, rather than the amount of incorporated Ag, governed the Ag(+) release and resulting antibacterial activity. The coating also demonstrated in vitro apatite-forming abilities, where structural variety along the sample was shown to alter the hydrophilic behavior, with the degree of hydroxyapatite deposition varying accordingly. By means of combinatorial synthesis, a single gradient sample was able to display intricate compositional and structural features affecting its biological response, which would otherwise require a series of coatings. The current findings suggest that future implant coatings incorporating Ag as an antibacterial agent could be structurally enhanced to better suit clinical requirements.

  9. Ytterbium amides of linked bis(amidinate): synthesis, molecular structures, and reactivity for the polymerization of L-lactide.

    PubMed

    Wang, Junfeng; Cai, Tao; Yao, Yingming; Zhang, Yong; Shen, Qi

    2007-12-07

    The steric effect of an amide group on the synthesis, molecular structures and reactivity of ytterbium amides supported by linked bis(amidinate) L (L = [Me3SiNC(Ph)N(CH2)3NC(Ph)NSiMe3]) is reported. Reaction of LYbCl(THF)2 with equimolar NaNHAr' and NaNHAr (Ar' = 2,6-Me2C6H3; Ar = 2,6-iPr2C6H3), respectively, gave the corresponding monometallic amide complexes LYb(NHAr')(DME) 1 and LYb(NHAr)(DME) 2, in which the linked bis(amidinate) is coordinated to the metal center as a chelating ligand. The similar reaction with NaN(SiMe3)2 afforded a bimetallic amide complex (TMS)2NYb(L)2YbN(TMS)2 3 formed through the rearrangement reaction of L induced by the bulky N(SiMe3)2 group. In complex 3 the two linked bis(amidinate)s act as bridging ancillary ligands to link two YbN(TMS)2 species in one molecule. The definite molecular structures of 1-3 were provided by single-crystal X-ray analysis. Complexes 1-3 are efficient initiators for the polymerization of L-lactide, and their catalytic performance is highly dependent on the amido groups and molecular structures. The polymerizations initiated by complexes 1 and 2 proceeded in a living fashion as evidenced by the narrow polydispersities of the resulting polymers, together with the linear natures of the number average molecular weight versus conversion plots, while the polymerization system with complex 3 provided polymers with rather broad molecular weight distributions.

  10. Surface functionalization of titanium dioxide nanoparticles: Photo-stability and reactive oxygen species (ROS) generation

    NASA Astrophysics Data System (ADS)

    Louis, Kacie M.

    Metal oxide nanoparticles are becoming increasingly prevalent in society for applications of sunscreens, cosmetics, paints, biomedical imaging, and photovoltaics. Due to the increased surface area to volume ratio of nanoparticles compared to bulk materials, it is important to know the health and safety impacts of these materials. One mechanism of toxicity of nominally "safe" materials such as TiO 2 is through the photocatalytic generation of reactive oxygen species (ROS). ROS production and ligand degradation can affect the bioavailability of these particles in aqueous organisms. We have investigated ROS generation by functionalized TiO2 nanoparticles and its influence on aggregation and bioavailability and toxicity to zebrafish embryos/larvae. For these studies we investigated anatase TiO2 nanoparticles. For application purposes and solution stability, the TiO2 nanoparticles were functionalized with a variety of ligands such as citrate, 3,4-dihydroxybenzaldehyde, and ascorbate. We quantitatively examined the amount of ROS produced in aqueous solution using fluorescent probes and see that more ROS is produced under UV light than in the dark control. Our measurements show that TiO2 toxicity reaches a maximum for nanoparticles with smaller diameters, and is correlated with surface area dependent changes in ROS generation. In an effort to reduce toxicity through control of the surface and surface ligands, we synthesized anatase nanoparticles of different sizes, functionalized them with different ligands, and examined the resulting ROS generation and ligand stability. Using a modular ligand containing a hydrophobic inner region and a hydrophilic outer region, we synthesized water-stable nanoparticles, via two different chemical reactions, having much-reduced ROS generation and thus reduced toxicity. These results suggest new strategies for making safer nanoparticles while still retaining their desired properties. We also examine the degradation of the different ligands

  11. Neither cyclosporine nor tacrolimus deteriorate endothelial function in renal transplant recipients assessed with reactive hyperernia index.

    PubMed

    Grabczewska, Z; Obońska, K; Adamowicz, A; Kasprzak, M; Włodarczyk, Z; Kubica, J

    2013-05-01

    Cardiovascular mortality in renal transplant recipients is nearer 10-fold higher than in general population. Immunosuppressive therapy is one possible cause, for these drugs can modify cardiovascular risk factors, which can induce endothelial dysfunction, the first step in the process of atherosclerosis. The aim of this study was to compare vasodilatatory function of endothelium in renal transplant recipients in relation to the immunosuppressive drug-cyclosporine or tacrolimus. We examined 40 patients at 48.9 ± 36 months post-renal transplantation: 22 taking tacrolimus (group 1) and 18 taking cyclosporine (group 2). The renal transplant recipients were compared with a control group of 18 healthy people. Endothelial function was assessed by peripheral arterial tonometry (PAT) using the EndoPAT 2000 device to measure RHI (reactive hyperemia index) and AI% (augmentation index%). The overall median values of RHI were higher than the value accepted as a normal (1.67). The RHI median value in group 1 was 2.00 (quartile 1: 1.66; quartile 2: 2.72), not different from that in group 2 [1.90 (quartile 1: 1.56; quartile 2: 2.17)] or the controls [2.11 (quartile 1: 1.77; quartile 2: 2.50)]. Multivariate analysis revealed age to be the independent factor influencing RHI in all examined groups but treatment with calcium channel blockers appeared to be the only independent factor influencing RHI among renal transplant recipients. AI% values were not significantly different between the 2 groups of renal transplant recipients, but it was significantly higher among the controls than among subjects treated with tacrolimus. Vasodilatatory function of endothelium assessed by PAT in renal transplant recipients was not worse than in healthy people. It was not different between cyclosporine or tacrolimus. Arterial stiffness measured as AI% depend on age but not the calcineurin inhibitor, which showed little effect. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. Neurocognitive function and state cognitive stress appraisal predict cortisol reactivity to an acute psychosocial stressor in adolescents.

    PubMed

    Slattery, Marcia J; Grieve, Adam J; Ames, Michelle E; Armstrong, Jeffrey M; Essex, Marilyn J

    2013-08-01

    Stress and associated alterations in hypothalamic-pituitary-adrenal (HPA) function have deleterious influence on the development of multiple mental and physical health problems. Prior research has aimed to identify individuals most at risk for the development of these stress-related maladies by examining factors that may contribute to inter-individual differences in HPA responses to acute stress. The objectives of this study were to investigate, in adolescents, (1) whether differences in neurocognitive abilities influenced cortisol reactivity to an acute stressor, (2) whether internalizing psychiatric disorders influenced this relationship, and (3) whether acute cognitive stress-appraisal mechanisms mediated an association between neurocognitive function and cortisol reactivity. Subjects were 70 adolescents from a community sample who underwent standardized neurocognitive assessments of IQ, achievement, and declarative memory measures at mean age 14 and whose physiological and behavioral responses to a standardized psychosocial stress paradigm (Trier Social Stress Test, TSST) were assessed at mean age 18. Results showed that, among all adolescents, lower nonverbal memory performance predicted lower cortisol reactivity. In addition, internalizing disorders interacted with verbal memory such that the association with cortisol reactivity was strongest for adolescents with internalizing disorders. Finally, lower secondary cognitive appraisal of coping in anticipation of the TSST independently predicted lower cortisol reactivity but did not mediate the neurocognitive-cortisol relationship. Findings suggest that declarative memory may contribute to inter-individual differences in acute cortisol reactivity in adolescents, internalizing disorders may influence this relationship, and cognitive stress appraisal also predicts cortisol reactivity. Developmental, research, and clinical implications are discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

  13. Diabetes and the impairment of reproductive function: possible role of mitochondria and reactive oxygen species.

    PubMed

    Amaral, Sandra; Oliveira, Paulo J; Ramalho-Santos, João

    2008-02-01

    Diabetes Mellitus (DM), a state of chronic hyperglycemia, is a major cause of serious micro and macrovascular diseases, affecting, therefore, nearly every system in the body. Growing evidence indicates that oxidative stress is increased in diabetes due to overproduction of reactive oxygen species (ROS) and decreased efficiency of antioxidant defences, a process that starts very early and worsens over the course of the disease. During the development of diabetes, oxidation of lipids, proteins and DNA increase with time. Mitochondrial DNA mutations have also been reported in diabetic tissues, suggesting oxidative stress-related mitochondrial damage. Diabetes-related oxidative stress may also be the trigger for many alterations on sexual function, which can also include decreased testicular mitochondrial function. Although sexual disorders have been extensively studied in diabetic men, possible changes in the sexual function of diabetic women have only recently received attention. The prevalence of sexual dysfunction in diabetic men approaches 50%, whereas in diabetic women it seems to be slightly lower. Testicular dysfunction, impotence, decreased fertility potential and retrograde ejaculations are conditions that have been described in diabetic males. Diabetes is also the most common cause of erectile dysfunction in men. Poor semen quality has also been reported in diabetic men, including decreased sperm motility and concentration, abnormal morphology and increased seminal plasma abnormalities. In addition, diabetic men may have decreased serum testosterone due to impaired Leydig cell function. Among diabetic women neuropathy, vascular impairment and psychological complaints have been implicated in the pathogenesis of decreased libido, low arousability, decreased vaginal lubrication, orgasmic dysfunction, and dyspareunia. An association between the production of excess radical oxygen species and disturbed embryogenesis in diabetic pregnancies has also been suggested

  14. Regioselective Synthesis of C-3-Functionalized Quinolines via Hetero-Diels-Alder Cycloaddition of Azadienes with Terminal Alkynes.

    PubMed

    Saunthwal, Rakesh K; Patel, Monika; Verma, Akhilesh K

    2016-08-05

    A highly efficient metal and protection-free approach for the regioselective synthesis of C-3-functionalized quinolines from azadienes (in situ generated from 2-aminobenzyl alcohol) and terminal alkynes through [4 + 2] cycloaddition has been developed. An unprecedented reaction of 2-aminobenzyl alcohol with 1,3- and 1,4-diethynylbenzene provided the C-3 tolylquinolines via [4 + 2] HDA and oxidative decarboxylation. The -NH2 group directed mechanistic approach was well supported by the control experiments and deuterium-labeling studies and by isolating the azadiene intermediate. The reactivity and selectivity of unprotected azadiene in metal-free base-assisted hetero-Diels-Alder reaction is exploited to quickly assemble an important class of C-3-functionalized quinolines, which are difficult to access.

  15. Hypothalamic Pituitary Adrenal Axis Functioning in Reactive and Proactive Aggression in Children

    ERIC Educational Resources Information Center

    Lopez-Duran, Nestor L.; Olson, Sheryl L.; Hajal, Nastassia J.; Felt, Barbara T.; Vazquez, Delia M.

    2009-01-01

    The purpose of this study was to examine the association between hypothalamic-pituitary-adrenal axis (HPA-axis) reactivity and proactive and reactive aggression in pre-pubertal children. After a 30-min controlled base line period, 73 7-year-old children (40 males and 33 females) were randomly assigned to one of two experimental tasks designed to…

  16. Hypothalamic Pituitary Adrenal Axis Functioning in Reactive and Proactive Aggression in Children

    ERIC Educational Resources Information Center

    Lopez-Duran, Nestor L.; Olson, Sheryl L.; Hajal, Nastassia J.; Felt, Barbara T.; Vazquez, Delia M.

    2009-01-01

    The purpose of this study was to examine the association between hypothalamic-pituitary-adrenal axis (HPA-axis) reactivity and proactive and reactive aggression in pre-pubertal children. After a 30-min controlled base line period, 73 7-year-old children (40 males and 33 females) were randomly assigned to one of two experimental tasks designed to…

  17. Synthesis, characterization, and reactivity of ruthenium diene/diamine complexes including catalytic hydrogenation of ketones.

    PubMed

    Morilla, M Esther; Rodríguez, Pilar; Belderrain, Tomas R; Graiff, Claudia; Tiripicchio, Antonio; Nicasio, M Carmen; Pérez, Pedro J

    2007-10-29

    Thermal reactions between [RuCl2(diene)]n (diene = 2,5-norbornadiene, nbd; 1,5-cyclooctadiene, cod) with an excess of N,N,N',N'-tetramethylethylene diamine (tmeda) afforded derivatives [RuCl2(diene)(tmeda)] (diene = nbd, 1; cod, 2) as a mixture of cis and trans isomers. When thermolysis was performed under H2 mixtures of hydride species [RuCl(H)(diene)(tmeda)] (diene = nbd, 3; cod, 4) and the bis-tmeda adduct trans-[RuCl2(tmeda)2] (5) were obtained in different ratios depending upon the reaction conditions and reaction times. Heating polymeric Ru(II) precursors in toluene in the presence of a 5-fold excess of the bulkier N,N,N',N'-tetraethylethylene diamine (teeda) resulted in a rare diamine dealkylation process with formation of trans-[RuCl2(nbd)(Et2NCH2CH2NHEt)] (6) and trans-[RuCl2(cod)(EtHNCH2CH2NHEt)] (7) in high yields. The presence of N-H functionalities in the coordinated diamine ligands of 6 and 7 was unambiguously established by single-crystal X-ray diffraction studies. The dealkylation process of the teeda ligand seems to proceed intramolecularly as shown by solution NMR studies performed with the soluble Ru(II) precursors trans-[RuCl2(amine)2(diene)] (diene = nbd, amine = morpholine, 9; diene = cod, amine = Et2NH, 10). The above complexes [RuCl2(diene)(diamine)] have been tested as precatalysts in the hydrogenation of ketones both for transfer as well as direct hydrogenation, the latter route being the most effective.

  18. Children's Patterns of Emotional Reactivity to Conflict as Explanatory Mechanisms in Links between Interpartner Aggression and Child Physiological Functioning

    ERIC Educational Resources Information Center

    Davies, Patrick T.; Sturge-Apple, Melissa L.; Cicchetti, Dante; Manning, Liviah G.; Zale, Emily

    2009-01-01

    Background: This paper examined children's fearful, sad, and angry reactivity to interparental conflict as mediators of associations between their exposure to interparental aggression and physiological functioning. Methods: Participants included 200 toddlers and their mothers. Assessments of interparental aggression and children's emotional…

  19. Children's Patterns of Emotional Reactivity to Conflict as Explanatory Mechanisms in Links between Interpartner Aggression and Child Physiological Functioning

    ERIC Educational Resources Information Center

    Davies, Patrick T.; Sturge-Apple, Melissa L.; Cicchetti, Dante; Manning, Liviah G.; Zale, Emily

    2009-01-01

    Background: This paper examined children's fearful, sad, and angry reactivity to interparental conflict as mediators of associations between their exposure to interparental aggression and physiological functioning. Methods: Participants included 200 toddlers and their mothers. Assessments of interparental aggression and children's emotional…

  20. Reactive sintering and reactive hot

    NASA Astrophysics Data System (ADS)

    Murray, J. C.; German, R. M.

    1992-09-01

    NbAl3 has been synthesized from elemental powders by reactive sintering (RS) and reactive hot isostatic pressing (RHIP). Both processes involve a self-propagating exothermic reaction between the constituent powders to form an intermetallic compound. The RHIP approach uses simultaneous external pressurization to make a higher density product. This study focused on developing a method to use reactive synthesis to form high-density NbAl3 compacts. High RS and RHIP densities were possible with the appropriate raw materials and processing parameters. These include powder purity, particle sizes, degassing, heating rate, furnace temperature, and compaction pressures. Near full density was attained with RHIP, and up to 95 pct density was attained with RS.

  1. Ligation of Glycophorin A Generates Reactive Oxygen Species Leading to Decreased Red Blood Cell Function.

    PubMed

    Khoory, Joseph; Estanislau, Jessica; Elkhal, Abdallah; Lazaar, Asmae; Melhorn, Mark I; Brodsky, Abigail; Illigens, Ben; Hamachi, Itaru; Kurishita, Yasutaka; Ivanov, Alexander R; Shevkoplyas, Sergey; Shapiro, Nathan I; Ghiran, Ionita C

    2016-01-01

    Acute, inflammatory conditions associated with dysregulated complement activation are characterized by significant increases in blood concentration of reactive oxygen species (ROS) and ATP. The mechanisms by which these molecules arise are not fully understood. In this study, using luminometric- and fluorescence-based methods, we show that ligation of glycophorin A (GPA) on human red blood cells (RBCs) results in a 2.1-fold, NADPH-oxidase-dependent increase in intracellular ROS that, in turn, trigger multiple downstream cascades leading to caspase-3 activation, ATP release, and increased band 3 phosphorylation. Functionally, using 2D microchannels to assess membrane deformability, GPS-ligated RBCs travel 33% slower than control RBCs, and lipid mobility was hindered by 10% using fluorescence recovery after photobleaching (FRAP). These outcomes were preventable by pretreating RBCs with cell-permeable ROS scavenger glutathione monoethyl ester (GSH-ME). Our results obtained in vitro using anti-GPA antibodies were validated using complement-altered RBCs isolated from control and septic patients. Our results suggest that during inflammatory conditions, circulating RBCs significantly contribute to capillary flow dysfunctions, and constitute an important but overlooked source of intravascular ROS and ATP, both critical mediators responsible for endothelial cell activation, microcirculation impairment, platelet activation, as well as long-term dysregulated adaptive and innate immune responses.

  2. Exploring the differential associations between components of executive functioning and reactive and proactive aggression.

    PubMed

    Hecht, Lisa K; Latzman, Robert D

    2017-04-18

    A large body of literature confirms the importance of executive functioning (EF) in the explanation of aggressive and antisocial behaviors. However, the common and specific associations between subtypes of aggression, such as reactive (RA), proactive aggression (PA), and EF are unclear. The current study explored the nuanced associations between components of EF and subtypes of aggression, using a latent variable approach. Participants were 384 racially diverse undergraduate students (ages 18-52 years) who completed a self-report measure of RA and PA, and traditional neuropsychological tasks of EF. The appropriateness of using a nested bifactor model of EF was confirmed, and this bifactor model of EF was then used to examine the specific associations between components of EF and RA and PA. Results revealed that components of EF are differentially associated with RA and PA. Specifically, impulsive, provoked aggression (i.e., RA) was associated with lower levels of goal-oriented inhibition and higher levels of flexibility, whereas planned, goal-oriented aggression (i.e., PA) was associated with higher levels of working memory. Findings from the current study underscore the importance of considering the multidimensional nature of EF, as well as the heterogeneity within aggression, rather than considering either construct as a single monolithic construct. The current study suggests that potentially unique brain-based pathways from aspects of EF to subtypes of aggression may exist, and points toward potential avenues through which to intervene.

  3. Autophagy proteins control goblet cell function by potentiating reactive oxygen species production.

    PubMed

    Patel, Khushbu K; Miyoshi, Hiroyuki; Beatty, Wandy L; Head, Richard D; Malvin, Nicole P; Cadwell, Ken; Guan, Jun-Lin; Saitoh, Tatsuya; Akira, Shizuo; Seglen, Per O; Dinauer, Mary C; Virgin, Herbert W; Stappenbeck, Thaddeus S

    2013-12-11

    Delivery of granule contents to epithelial surfaces by secretory cells is a critical physiologic process. In the intestine, goblet cells secrete mucus that is required for homeostasis. Autophagy proteins are required for secretion in some cases, though the mechanism and cell biological basis for this requirement remain unknown. We found that in colonic goblet cells, proteins involved in initiation and elongation of autophagosomes were required for efficient mucus secretion. The autophagy protein LC3 localized to intracellular multi-vesicular vacuoles that were consistent with a fusion of autophagosomes and endosomes. Using cultured intestinal epithelial cells, we found that NADPH oxidases localized to and enhanced the formation of these LC3-positive vacuoles. Both autophagy proteins and endosome formation were required for maximal production of reactive oxygen species (ROS) derived from NADPH oxidases. Importantly, generation of ROS was critical to control mucin granule accumulation in colonic goblet cells. Thus, autophagy proteins can control secretory function through ROS, which is in part generated by LC3-positive vacuole-associated NADPH oxidases. These findings provide a novel mechanism by which autophagy proteins can control secretion.

  4. Autophagy proteins control goblet cell function by potentiating reactive oxygen species production

    PubMed Central

    Patel, Khushbu K; Miyoshi, Hiroyuki; Beatty, Wandy L; Head, Richard D; Malvin, Nicole P; Cadwell, Ken; Guan, Jun-Lin; Saitoh, Tatsuya; Akira, Shizuo; Seglen, Per O; Dinauer, Mary C; Virgin, Herbert W; Stappenbeck, Thaddeus S

    2013-01-01

    Delivery of granule contents to epithelial surfaces by secretory cells is a critical physiologic process. In the intestine, goblet cells secrete mucus that is required for homeostasis. Autophagy proteins are required for secretion in some cases, though the mechanism and cell biological basis for this requirement remain unknown. We found that in colonic goblet cells, proteins involved in initiation and elongation of autophagosomes were required for efficient mucus secretion. The autophagy protein LC3 localized to intracellular multi-vesicular vacuoles that were consistent with a fusion of autophagosomes and endosomes. Using cultured intestinal epithelial cells, we found that NADPH oxidases localized to and enhanced the formation of these LC3-positive vacuoles. Both autophagy proteins and endosome formation were required for maximal production of reactive oxygen species (ROS) derived from NADPH oxidases. Importantly, generation of ROS was critical to control mucin granule accumulation in colonic goblet cells. Thus, autophagy proteins can control secretory function through ROS, which is in part generated by LC3-positive vacuole-associated NADPH oxidases. These findings provide a novel mechanism by which autophagy proteins can control secretion. PMID:24185898

  5. Ventral striatum dysfunction in children and adolescents with reactive attachment disorder: functional MRI study

    PubMed Central

    Takiguchi, Shinichiro; Fujisawa, Takashi X.; Mizushima, Sakae; Saito, Daisuke N.; Okamoto, Yuko; Shimada, Koji; Koizumi, Michiko; Kumazaki, Hirokazu; Jung, Minyoung; Kosaka, Hirotaka; Hiratani, Michio; Ohshima, Yusei; Teicher, Martin H.

    2015-01-01

    Background Child maltreatment is a major risk factor for psychopathology, including reactive attachment disorder (RAD). Aims To examine whether neural activity during reward processing was altered in children and adolescents with RAD. Method Sixteen children and adolescents with RAD and 20 typically developing (TD) individuals performed tasks with high and low monetary rewards while undergoing functional magnetic resonance imaging. Results Significantly reduced activity in the caudate and nucleus accumbens was observed during the high monetary reward condition in the RAD group compared with the TD group (P=0.015, family-wise error-corrected cluster level). Significant negative correlations between bilateral striatal activity and avoidant attachment were observed in the RAD and TD groups. Conclusions Striatal neural reward activity in the RAD group was markedly decreased. The present results suggest that dopaminergic dysfunction occurs in the striatum of children and adolescents with RAD, leading towards potential future risks for psychopathology. Declaration of interest None. Copyright and usage © The Royal College of Psychiatrists 2015. This is an open access article distributed under the terms of the Creative Commons Non-Commercial, No Derivatives (CC BY-NC-ND) licence. PMID:27703736

  6. Lung function and bronchial reactivity in asthmatics during exposure to volatile organic compounds

    SciTech Connect

    Harving, H.; Dahl, R.; Molhave, L. )

    1991-04-01

    The purpose of the present study was to investigate whether vapors of organic solvents at low concentrations could exert an adverse effect in the lower airways. Under controlled conditions in a climate chamber, 11 persons with bronchial hyperreactivity to histamine and bronchial asthma were exposed for 90 min to a mixture of organic solvents at levels of zero, 2.5, and 25 mg/m3. During exposure to 25 mg/m3 a decrease in FEV1 to 90.7% of baseline value was measured. This was significantly different from the initial value (p less than 0.05), but not significantly different from the value found after sham exposure (FEV1, 97.4% of initial value). The decline in FEV1 during exposure to 25 mg/m3 was most pronounced in persons with high bronchial sensitivity. No changes were found in histamine reactivity after exposure, and no late reactions were registered. Ratings of discomfort showed different individual patterns ranging from no response to reactions towards both of the concentrations. The ratings indicated development of tolerance during exposure. Volatile organic compounds in concentrations found in both the work and the home environments may influence lung function and are probably of importance as bronchial irritants.

  7. Convergent functional genomic studies of omega-3 fatty acids in stress reactivity, bipolar disorder and alcoholism

    PubMed Central

    Le-Niculescu, H; Case, N J; Hulvershorn, L; Patel, S D; Bowker, D; Gupta, J; Bell, R; Edenberg, H J; Tsuang, M T; Kuczenski, R; Geyer, M A; Rodd, Z A; Niculescu, A B

    2011-01-01

    Omega-3 fatty acids have been proposed as an adjuvant treatment option in psychiatric disorders. Given their other health benefits and their relative lack of toxicity, teratogenicity and side effects, they may be particularly useful in children and in females of child-bearing age, especially during pregnancy and postpartum. A comprehensive mechanistic understanding of their effects is needed. Here we report translational studies demonstrating the phenotypic normalization and gene expression effects of dietary omega-3 fatty acids, specifically docosahexaenoic acid (DHA), in a stress-reactive knockout mouse model of bipolar disorder and co-morbid alcoholism, using a bioinformatic convergent functional genomics approach integrating animal model and human data to prioritize disease-relevant genes. Additionally, to validate at a behavioral level the novel observed effects on decreasing alcohol consumption, we also tested the effects of DHA in an independent animal model, alcohol-preferring (P) rats, a well-established animal model of alcoholism. Our studies uncover sex differences, brain region-specific effects and blood biomarkers that may underpin the effects of DHA. Of note, DHA modulates some of the same genes targeted by current psychotropic medications, as well as increases myelin-related gene expression. Myelin-related gene expression decrease is a common, if nonspecific, denominator of neuropsychiatric disorders. In conclusion, our work supports the potential utility of omega-3 fatty acids, specifically DHA, for a spectrum of psychiatric disorders such as stress disorders, bipolar disorder, alcoholism and beyond. PMID:22832392

  8. Functional indexes of reactive cognitive control: ERPs in cued go/no-go tasks.

    PubMed

    Kropotov, Juri D; Ponomarev, Valery A; Pronina, Marina; Jäncke, Lutz

    2017-08-03

    We aimed to determine the functional meaning of latent (hidden) components decomposed from ERPs, in the context of a go/no-go paradigm. To accomplish this, we used a new group blind source separation method, based on joint diagonalization of covariance matrices of ERPs. Four variants of a frequently used go/no-go paradigm were designed, in which operations of reactive cognitive control, such as conflict detection and action inhibition, were independently manipulated. The results showed that a latent component, generated in the anterior cingulate cortex, induced N2/P3 fluctuation only in conditions in which the prepotent model was violated, and thus can be associated with conflict detection operations. In contrast, the two latent components generated in the vicinity of the central sulcus induced P3-like fluctuations in conditions in which the prepared action was suppressed, and thus can be associated with action inhibition operations. The advantages and limitations of the new blind source separation method in relation to ERP research are also discussed. © 2017 Society for Psychophysiological Research.

  9. Ligation of Glycophorin A Generates Reactive Oxygen Species Leading to Decreased Red Blood Cell Function

    PubMed Central

    Khoory, Joseph; Estanislau, Jessica; Elkhal, Abdallah; Lazaar, Asmae; Melhorn, Mark I.; Brodsky, Abigail; Illigens, Ben; Hamachi, Itaru; Kurishita, Yasutaka; Ivanov, Alexander R.; Shevkoplyas, Sergey; Shapiro, Nathan I.; Ghiran, Ionita C.

    2016-01-01

    Acute, inflammatory conditions associated with dysregulated complement activation are characterized by significant increases in blood concentration of reactive oxygen species (ROS) and ATP. The mechanisms by which these molecules arise are not fully understood. In this study, using luminometric- and fluorescence-based methods, we show that ligation of glycophorin A (GPA) on human red blood cells (RBCs) results in a 2.1-fold, NADPH-oxidase-dependent increase in intracellular ROS that, in turn, trigger multiple downstream cascades leading to caspase-3 activation, ATP release, and increased band 3 phosphorylation. Functionally, using 2D microchannels to assess membrane deformability, GPS-ligated RBCs travel 33% slower than control RBCs, and lipid mobility was hindered by 10% using fluorescence recovery after photobleaching (FRAP). These outcomes were preventable by pretreating RBCs with cell-permeable ROS scavenger glutathione monoethyl ester (GSH-ME). Our results obtained in vitro using anti-GPA antibodies were validated using complement-altered RBCs isolated from control and septic patients. Our results suggest that during inflammatory conditions, circulating RBCs significantly contribute to capillary flow dysfunctions, and constitute an important but overlooked source of intravascular ROS and ATP, both critical mediators responsible for endothelial cell activation, microcirculation impairment, platelet activation, as well as long-term dysregulated adaptive and innate immune responses. PMID:26784696

  10. Convergent functional genomic studies of ω-3 fatty acids in stress reactivity, bipolar disorder and alcoholism.

    PubMed

    Le-Niculescu, H; Case, N J; Hulvershorn, L; Patel, S D; Bowker, D; Gupta, J; Bell, R; Edenberg, H J; Tsuang, M T; Kuczenski, R; Geyer, M A; Rodd, Z A; Niculescu, A B

    2011-04-26

    Omega-3 fatty acids have been proposed as an adjuvant treatment option in psychiatric disorders. Given their other health benefits and their relative lack of toxicity, teratogenicity and side effects, they may be particularly useful in children and in females of child-bearing age, especially during pregnancy and postpartum. A comprehensive mechanistic understanding of their effects is needed. Here we report translational studies demonstrating the phenotypic normalization and gene expression effects of dietary omega-3 fatty acids, specifically docosahexaenoic acid (DHA), in a stress-reactive knockout mouse model of bipolar disorder and co-morbid alcoholism, using a bioinformatic convergent functional genomics approach integrating animal model and human data to prioritize disease-relevant genes. Additionally, to validate at a behavioral level the novel observed effects on decreasing alcohol consumption, we also tested the effects of DHA in an independent animal model, alcohol-preferring (P) rats, a well-established animal model of alcoholism. Our studies uncover sex differences, brain region-specific effects and blood biomarkers that may underpin the effects of DHA. Of note, DHA modulates some of the same genes targeted by current psychotropic medications, as well as increases myelin-related gene expression. Myelin-related gene expression decrease is a common, if nonspecific, denominator of neuropsychiatric disorders. In conclusion, our work supports the potential utility of omega-3 fatty acids, specifically DHA, for a spectrum of psychiatric disorders such as stress disorders, bipolar disorder, alcoholism and beyond.

  11. Process signatures in glatiramer acetate synthesis: structural and functional relationships.

    PubMed

    Campos-García, Víctor R; Herrera-Fernández, Daniel; Espinosa-de la Garza, Carlos E; González, German; Vallejo-Castillo, Luis; Avila, Sandra; Muñoz-García, Leslie; Medina-Rivero, Emilio; Pérez, Néstor O; Gracia-Mora, Isabel; Pérez-Tapia, Sonia Mayra; Salazar-Ceballos, Rodolfo; Pavón, Lenin; Flores-Ortiz, Luis F

    2017-09-21

    Glatiramer Acetate (GA) is an immunomodulatory medicine approved for the treatment of multiple sclerosis, whose mechanisms of action are yet to be fully elucidated. GA is comprised of a complex mixture of polypeptides with different amino acid sequences and structures. The lack of sensible information about physicochemical characteristics of GA has contributed to its comprehensiveness complexity. Consequently, an unambiguous determination of distinctive attributes that define GA is of highest relevance towards dissecting its identity. Herein we conducted a study of characteristic GA heterogeneities throughout its manufacturing process (process signatures), revealing a strong impact of critical process parameters (CPPs) on the reactivity of amino acid precursors; reaction initiation and polymerization velocities; and peptide solubility, susceptibility to hydrolysis, and size-exclusion properties. Further, distinctive GA heterogeneities were correlated to defined immunological and toxicological profiles, revealing that GA possesses a unique repertoire of active constituents (epitopes) responsible of its immunological responses, whose modification lead to altered profiles. This novel approach established CPPs influence on intact GA peptide mixture, whose physicochemical identity cannot longer rely on reduced properties (based on complete or partial GA degradation), providing advanced knowledge on GA structural and functional relationships to ensure a consistent manufacturing of safe and effective products.

  12. Highly luminescent half-lantern cyclometalated platinum(II) complex: synthesis, structure, luminescence studies, and reactivity.

    PubMed

    Sicilia, Violeta; Forniés, Juan; Casas, José Ma; Martín, Antonio; López, José A; Larraz, Carmen; Borja, Pilar; Ovejero, Carmen; Tordera, Daniel; Bolink, Henk

    2012-03-19

    The half-lantern compound [{Pt(bzq)(μ-C(7)H(4)NS(2)-κN,S)}(2)]·Me(2)CO (1) was obtained by reaction of equimolar amounts of potassium 2-mercaptobenzothiazolate (KC(7)H(4)NS(2)) and [Pt(bzq)(NCMe)(2)]ClO(4). The Pt(II)···Pt(II) separation in the neutral complex [{Pt(bzq)(μ-C(7)H(4)NS(2)-κN,S)}(2)] is 2.910 (2) Å, this being among the shortest observed in half-lantern divalent platinum complexes. Within the complex, the benzo[h]quinoline (bzq) groups lie in close proximity with most C···C distances being between 3.3 and 3.7 Å, which is indicative of significant π-π interactions. The reaction of 1 with halogens X(2) (X(2) = Cl(2), Br(2), or I(2)) proceeds with a two-electron oxidation to give the corresponding dihalodiplatinum(III) complexes [{Pt(bzq)(μ-C(7)H(4)NS(2)-κN,S)X}(2)] (X = Cl 2, Br 3, I 4). Their X-ray structures confirm the retention of the half-lantern structure and the coordination mode of the bzq and the bridging ligand μ-C(7)H(4)NS(2)-κN,S. The Pt-Pt distances (Pt-Pt = 2.6420(3) Å 2, 2.6435(4) Å 3, 2.6690(3) Å 4) are shorter than that in 1 because of the Pt-Pt bond formation. Time dependent-density functional theory (TD-DFT) studies performed on 1 show a formal bond order of 0 between the metal atoms, with the 6p(z) contribution diminishing the antibonding character of the highest occupied molecular orbital (HOMO) and being responsible for an attractive intermetallic interaction. A shortening of the Pt-Pt distance from 2.959 Å in the ground state S(0) to 2.760 Å in the optimized first excited state (T(1)) is consistent with an increase in the Pt-Pt bond order to 0.5. In agreement with TD-DFT calculations, the intense, structureless, red emission of 1 in the solid state and in solution can be mainly attributed to triplet metal-metal-to-ligand charge transfer ((3)MMLCT) [dσ*(Pt-Pt) → π*(bzq)] excited states. The high quantum yields of this emission measured in toluene (44%) and solid state (62%) at room temperature indicate

  13. Phase-controlled synthesis of Cu2ZnSnS4 nanocrystals: the role of reactivity between Zn and S.

    PubMed

    Zou, Yu; Su, Xiong; Jiang, Jiang

    2013-12-11

    Cu2ZnSnS4 (CZTS) nanocrystals with different morphologies and phases have been synthesized in hot organic solvents such as dodecanethiol and oleylamine. The crystallographic phases could be controlled by the sulfur precursor and the ligand species of the metal salts used for the synthesis. When a highly reactive sulfur precursor and metal acetates were used, wurtzite CZTS nanocrystals were obtained. On the other hand, using a low-reactivity sulfur precursor or metal chlorides produced CZTS nanocrystals in a kesterite phase. The experimental results from systematic investigations indicated that the reaction rate between Zn and S precursors played a determining role for the growth of CZTS nanocrystals with different crystalline phases. A relatively faster reaction between Zn and S precursors in comparison to the Sn-S reaction favored the formation of a metastable wurtzite phase, which could be accelerated by increasing the reactivity of the S precursor. This work provided a safe and economical way to synthesize high-quality phase-controlled Cu2ZnSnS4 nanocrystals, especially wurtzite nanorods, for potential photovoltaic applications. Moreover, preliminary results show that the proposed mechanism also applies to the phase-controlled synthesis of other quaternary Cu2MSnS4 (M = Cd(2+), Mn(2+)) nanocrystals.

  14. Facile and High-Throughput Synthesis of Functional Microparticles with Quick Response Codes.

    PubMed

    Ramirez, Lisa Marie S; He, Muhan; Mailloux, Shay; George, Justin; Wang, Jun

    2016-06-01

    Encoded microparticles are high demand in multiplexed assays and labeling. However, the current methods for the synthesis and coding of microparticles either lack robustness and reliability, or possess limited coding capacity. Here, a massive coding of dissociated elements (MiCODE) technology based on innovation of a chemically reactive off-stoichimetry thiol-allyl photocurable polymer and standard lithography to produce a large number of quick response (QR) code microparticles is introduced. The coding process is performed by photobleaching the QR code patterns on microparticles when fluorophores are incorporated into the prepolymer formulation. The fabricated encoded microparticles can be released from a substrate without changing their features. Excess thiol functionality on the microparticle surface allows for grafting of amine groups and further DNA probes. A multiplexed assay is demonstrated using the DNA-grafted QR code microparticles. The MiCODE technology is further characterized by showing the incorporation of BODIPY-maleimide (BDP-M) and Nile Red fluorophores for coding and the use of microcontact printing for immobilizing DNA probes on microparticle surfaces. This versatile technology leverages mature lithography facilities for fabrication and thus is amenable to scale-up in the future, with potential applications in bioassays and in labeling consumer products.

  15. Evolution of New Enzymatic Function by Structural Modulation of Cysteine Reactivity in Pseudomonas fluorescens Isocyanide Hydratase*

    PubMed Central

    Lakshminarasimhan, Mahadevan; Madzelan, Peter; Nan, Ruth; Milkovic, Nicole M.; Wilson, Mark A.

    2010-01-01

    Isocyanide (formerly isonitrile) hydratase (EC 4.2.1.103) is an enzyme of the DJ-1 superfamily that hydrates isocyanides to yield the corresponding N-formamide. In order to understand the structural basis for isocyanide hydratase (ICH) catalysis, we determined the crystal structures of wild-type and several site-directed mutants of Pseudomonas fluorescens ICH at resolutions ranging from 1.0 to 1.9 Å. We also developed a simple UV-visible spectrophotometric assay for ICH activity using 2-naphthyl isocyanide as a substrate. ICH contains a highly conserved cysteine residue (Cys101) that is required for catalysis and interacts with Asp17, Thr102, and an ordered water molecule in the active site. Asp17 has carboxylic acid bond lengths that are consistent with protonation, and we propose that it activates the ordered water molecule to hydrate organic isocyanides. In contrast to Cys101 and Asp17, Thr102 is tolerant of mutagenesis, and the T102V mutation results in a substrate-inhibited enzyme. Although ICH is similar to human DJ-1 (1.6 Å C-α root mean square deviation), structural differences in the vicinity of Cys101 disfavor the facile oxidation of this residue that is functionally important in human DJ-1 but would be detrimental to ICH activity. The ICH active site region also exhibits surprising conformational plasticity and samples two distinct conformations in the crystal. ICH represents a previously uncharacterized clade of the DJ-1 superfamily that possesses a novel enzymatic activity, demonstrating that the DJ-1 core fold can evolve diverse functions by subtle modulation of the environment of a conserved, reactive cysteine residue. PMID:20630867

  16. Carbon dioxide reactivity of computed tomography functional parameters in rabbit VX2 soft tissue tumour

    NASA Astrophysics Data System (ADS)

    Purdie, Thomas G.; Lee, Ting-Yim

    2003-04-01

    Tumour blood flow is one of the important factors limiting the efficacy of radiation therapy (hypoxic radioresistance), chemotherapy (drug delivery) and thermal therapy (heat dissipation) in treating cancer. The modification of tumour blood flow has been an area of intense investigation. In the current study, the arterial carbon dioxide tension (PaCO2) was changed in order to investigate the tumour vascular response to carbon dioxide. Functional maps of blood flow, blood volume and mean transit time were generated at four PaCO2 levels in VX2 tumour in the rabbit thigh and normal soft tissue. The PaCO2 levels investigated were normocapnia (PaCO2 = 40.9 +/- 1.2 mmHg), hypocapnia (27.2 +/- 2.3 and 33.5 +/- 2.3 mmHg) and hypercapnia (54.9 +/- 4.4 mmHg). The carbon dioxide reactivity of the global tumour blood flow and mean transit time showed significant differences between normocapnia and the two levels of hypocapnia, but not between normocapnia and hypercapnia. The average fractional change of blood flow from normocapnia for the two levels of hypocapnia was -0.41 +/- 0.06 and -0.29 +/- 0.08, respectively (P < 0.05). In the case of mean transit time the fractional change was +0.39 +/- 0.30 and +0.23 +/- 0.24, respectively (P < 0.05). The fractional change of blood volume from normocapnia, however, was not significantly different at any capnic level, as was the case with respect to each of the functional parameters in normal tissue. The ability to reduce blood flow and increase mean transit time through hypocapnia has significant implications in thermal therapy, since heat dissipation is a major factor in limiting the effectiveness of treatment.

  17. Evolution of New Enzymatic Function by Structural Modulation of Cysteine Reactivity in Pseudomonas fluorescens Isocyanide Hydratase

    SciTech Connect

    Lakshminarasimhan, Mahadevan; Madzelan, Peter; Nan, Ruth; Milkovic, Nicole M.; Wilson, Mark A.

    2010-09-13

    Isocyanide (formerly isonitrile) hydratase (EC 4.2.1.103) is an enzyme of the DJ-1 superfamily that hydrates isocyanides to yield the corresponding N-formamide. In order to understand the structural basis for isocyanide hydratase (ICH) catalysis, we determined the crystal structures of wild-type and several site-directed mutants of Pseudomonas fluorescens ICH at resolutions ranging from 1.0 to 1.9 {angstrom}. We also developed a simple UV-visible spectrophotometric assay for ICH activity using 2-naphthyl isocyanide as a substrate. ICH contains a highly conserved cysteine residue (Cys101) that is required for catalysis and interacts with Asp17, Thr102, and an ordered water molecule in the active site. Asp17 has carboxylic acid bond lengths that are consistent with protonation, and we propose that it activates the ordered water molecule to hydrate organic isocyanides. In contrast to Cys101 and Asp17, Thr102 is tolerant of mutagenesis, and the T102V mutation results in a substrate-inhibited enzyme. Although ICH is similar to human DJ-1 (1.6 {angstrom} C-{alpha} root mean square deviation), structural differences in the vicinity of Cys101 disfavor the facile oxidation of this residue that is functionally important in human DJ-1 but would be detrimental to ICH activity. The ICH active site region also exhibits surprising conformational plasticity and samples two distinct conformations in the crystal. ICH represents a previously uncharacterized clade of the DJ-1 superfamily that possesses a novel enzymatic activity, demonstrating that the DJ-1 core fold can evolve diverse functions by subtle modulation of the environment of a conserved, reactive cysteine residue.

  18. Self-Assembly for the Synthesis of Functional Biomaterials

    PubMed Central

    Stephanopoulos, Nicholas; Ortony, Julia H.; Stupp, Samuel I.

    2012-01-01

    The use of self-assembly for the construction of functional biomaterials is a highly promising and exciting area of research, with great potential for the treatment of injury or disease. By using multiple noncovalent interactions, coded into the molecular design of the constituent components, self-assembly allows for the construction of complex, adaptable, and highly tunable materials with potent biological effects. This review describes some of the seminal advances in the use of self-assembly to make novel systems for regenerative medicine and biology. Materials based on peptides, proteins, DNA, or hybrids thereof have found application in the treatment of a wide range of injuries and diseases, and this review outlines the design principles and practical applications of these systems. Most of the examples covered focus on the synthesis of hydrogels for the scaffolding or transplantation of cells, with an emphasis on the biological, mechanical, and structural properties of the resulting materials. In addition, we will discuss the distinct advantages conferred by self-assembly (compared with traditional covalent materials), and present some of the challenges and opportunities for the next generation of self-assembled biomaterials. PMID:23457423

  19. Infant food applications of complex carbohydrates: Structure, synthesis, and function.

    PubMed

    Ackerman, Dorothy L; Craft, Kelly M; Townsend, Steven D

    2017-01-02

    Professional health bodies such as the World Health Organization (WHO), the American Academy of Pediatrics (AAP), and the U.S. Department of Health and Human Services (HHS) recommend breast milk as the sole source of food during the first year of life. This position recognizes human milk as being uniquely suited for infant nutrition. Nonetheless, most neonates in the West are fed alternatives by 6 months of age. Although inferior to human milk in most aspects, infant formulas are able to promote effective growth and development. However, while breast-fed infants feature a microbiota dominated by bifidobacteria, the bacterial flora of formula-fed infants is usually heterogeneous with comparatively lower levels of bifidobacteria. Thus, the objective of any infant food manufacturer is to prepare a product that results in a formula-fed infant developing a breast-fed infant-like microbiota. The goal of this focused review is to discuss the structure, synthesis, and function of carbohydrate additives that play a role in governing the composition of the infant microbiome and have other health benefits.

  20. Transportation management center functions. A synthesis of highway practice

    SciTech Connect

    Kraft, W.H.

    1998-12-31

    Transportation management centers (TMCs), or traffic management centers, have become a vital part of the transportation fabric in many urban areas. This synthesis presents information on the current operational and technical practices used by highway, transit, and multimodal TMCs in several urbanized areas. It also provides information to developers and suppliers of hardware and software for traffic control technology and communications systems. This report of the Transportation Research Board describes the various types of TMCs, their functions, and details of design, operations, and staffing. It describes the practice of agencies in the United States and Canada, based on survey responses from 147 TMCs. These agencies are responsible for highways, surface streets, bridges and tunnels, transit, including bus and rail, and several integrated TMCs that include more than one mode. Design criteria describe in detail the physical facility design of TMCs, as well as the software configurations and the interrelationships among TMCs of various types. The required staffing and the personnel roles are highlighted. To the extent that data are available, ranges of costs and benefits for TMCs are included in this report.

  1. Thrombospondin 1 synthesis and function in wound repair.

    PubMed Central

    DiPietro, L. A.; Nissen, N. N.; Gamelli, R. L.; Koch, A. E.; Pyle, J. M.; Polverini, P. J.

    1996-01-01

    Thrombospondin 1 (TSP1) is a multifunctional extracellular matrix molecule that belongs to a family of homologous glycoproteins. TSP1 can be produced by many cell types that are involved in wound repair, including keratinocytes, fibroblasts, endothelial cells, and macrophages. To investigate the kinetics of TSP1 synthesis in wounds, mRNA from murine full thickness excisional dermal wounds was analyzed. TSP1 mRNA was undetectable in normal skin but was present in early wounds. After day 1, TSP1 mRNA levels within wounds slowly decreased, returning to undectable day 10. In situ hybridization revealed that the primary source of the TSP1 mRNA within wounds was macrophage-like cells in the inflammatory infiltrate. To explore the function of TSP1 production in sites of injury, wounds were treated with antisense TSP1 oligomers. Antisense-treated wounds contained 55 to 66% less TSP1-positive macrophages than control and exhibited a marked delay in repair. This delay included a decreased rate of re-epithelialization as well as a delay in dermal reorganization. The results suggest that TSP1 production by macrophages facilitates the repair process and provide evidence that TSP1 production is an important component of optimal wound healing. Images Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 PMID:8669471

  2. The N cycle in Earth subsurface. Reactivity of functional genes to anthropogenic CO2 injections.

    NASA Astrophysics Data System (ADS)

    Trias, Rosalia; Gérard, Emmanuelle; Le Campion, Paul; Gíslason, Sigurður R.; Aradóttir, Edda S.; Alfreðsson, Helgui A.; Mesfin, Kiflom G.; Snæbjörnsdóttir, Sandra Ó.; Ménez, Bénédicte

    2014-05-01

    The Nitrogen cycle has been widely studied in surface ecosystems, due to the importance of this nutrient for the organisms' development, and to the impact in the environment of most of the N forms, many of them being considered pollutants. However, little is known about the importance of the N-related metabolisms in subsurface systems now recognized to host diverse and active microbial life. In this study, we have periodically sampled the subsurface aquifers of the Icelandic pilot site for CO2 storage associated with the geothermal plant of Hellisheidi (operated by Reykjavik Energy; http://www.or.is/en/projects/carbfix). With the aim of understanding the dynamics of N-cycle in the subsurface, and its reactivity to CO2 injections, we quantified through qPCR the functional genes amoA (archaea), amoA (bacteria), nirK, nirS, nosZ, nifH, and the 16SrRNA genes of the anammox, total archaea and total bacteria. The 16SrRNA gene quantification provided values of around 107 gene copies/l at non injection periods. CO2 injection caused first a slight decrease probably due to pH decrease or toxicity by oxygen contamination during the injections. Two months after injection, the copy numbers increased up to 109 gene copies/l, and slowly returned to pre-injection values. The archaeal 16S rDNA copy numbers showed a similar reaction, with higher toxicity effects, and a lower increase afterwards. Due to the high reactivity of the microbial populations to CO2 injections, all the N cycle quantifications were related to the total 16S rDNA copies for normalization. Nitrifying genes (amoA) were mainly represented by the ammonia oxidizing archaea, and were apparently not affected by CO2 injections. Anammox bacteria were present in a very low percentage, and the obtained copy numbers tended to decrease after the injection. These results were surprising due to the autotrophic character of ammonia oxidizers, but could be explained by a competitive exclusion. On the contrary, N-fixation (nif

  3. Functional group influences on the reactive azo dye decolorization performance by electrochemical oxidation and electro-Fenton technologies.

    PubMed

    da Costa Soares, Izabelle Cristina; da Silva, Djalma Ribeiro; do Nascimento, José Heriberto Oliveira; Garcia-Segura, Sergi; Martínez-Huitle, Carlos Alberto

    2017-09-07

    Electrochemical water treatment technologies are highly promising to achieve complete decolorization of dyebath effluents, as demonstrated by several studies reported in the literature. However, these works are focused on the treatment of one model pollutant and generalize the performances of the processes which are not transposable since they depend on the pollutant treated. Thus, in the present study, we evaluate, for the first time, the influence of different functional groups that modify the dye structure on the electrochemical process decolorization performance. The textile azo dyes Reactive Orange 16, Reactive Violet 4, Reactive Red 228, and Reactive Black 5 have been selected because they present the same molecular basis structure with different functional groups. The results demonstrate that the functional groups that reduce the nucleophilicity of the pollutant hinder the electrophilic attack of electrogenerated hydroxyl radical. Thereby, the overall decolorization efficiency is consequently reduced as well as the decolorization rate. Moreover, the presence of an additional chromophore azo bond in the molecule enhances the recalcitrant character of the azo dyes as pollutants. The formation of a larger and more stable conjugated π system increases the activation energy required for the electrophyilic attack of (•)OH, affecting the performance of electrochemical technologies on effluent decolorization.

  4. Effects of stress and chronic propranolol infusion on cardiac beta-receptor function in the Maudsley Reactive and Non-Reactive rat strains

    SciTech Connect

    Christ, G.J.; Pieper, J.A.; Blizard, D.A.; Dunlap, C.E. III

    1988-01-01

    The effects of ..beta..-adrenocepter blockade on left ventricular ..beta..-receptor characteristics were evaluated in the Maudsley Reactive (MR/Har) and Non-Reactive (MNRA/Har) rat strain. After propranolol infusion for one week administered by subcutaneously implanted osmotic minipumps, differences in ..beta..-adrenoceptor-agonist interactions between strains were assessed by comparison of isoproterenol competition for (/sup 125/I) iodocyanopindolol (ICYP) binding sites in crude left ventricular homogenate preparation from both strains. Propranolol exposure had no significant effect on the binding parameters investigated. In contrast to previous observations in naive animals, these experiments revealed no strain differences in the sham-implanted Maudsleys in any of the left ventricular ..beta..-adrenoceptor parameters investigated. The authors hypothesize that the surgical procedures and/or presence of the plastic inserts acted as stressors in the Maudsley strains and thus altered ..beta..-adrenoceptor function. This hypothesis is supported by the observation that exposure to another stress (footshock) also eliminated strain differences in ventricular ..beta..-receptor variables.

  5. The intestinal-renal axis for arginine synthesis is present and functional in the neonatal pig

    USDA-ARS?s Scientific Manuscript database

    The intestinal-renal axis for endogenous arginine synthesis is an interorgan process in which citrulline produced in the small intestine is utilized by the kidney for arginine synthesis. The function of this axis in neonates has been questioned because during this period the enzymes needed for argin...

  6. Studies with Hydroxyurea VII. Hydroxyurea and the Synthesis of Functional Proteins

    PubMed Central

    Rosenkranz, Herbert S.; Winshell, Elaine B.; Mednis, Aiga; Carr, Howard S.; Ellner, Cornelia J.

    1967-01-01

    Hydroxyurea affected neither the synthesis nor the degradation of bacterial messenger-ribonucleic acid. The proteins made by hydroxyurea-treated cells were structurally intact and fully functional. Since the expression of the lethal action of hydroxyurea requires active protein production, the data indicate that treated cells do not die as the result of the synthesis of abnormal proteins. Images PMID:4963772

  7. Lithium-ion polymer cells assembled with a reactive composite separator containing vinyl-functionalized SiO2 particles

    NASA Astrophysics Data System (ADS)

    Yoo, Ji-Hyun; Shin, Won-Kyung; Koo, Sang Man; Kim, Dong-Won

    2015-11-01

    Vinyl-functionalized SiO2 particles of different sizes are synthesized and coated onto both sides of a polyethylene separator to prepare a reactive composite separator for lithium-ion polymer cells. The SiO2-coated composite separators exhibit excellent thermal stability due to the presence of heat-resistant silica particles. By using these reactive composite separators and a gel electrolyte precursor, lithium-ion polymer cells composed of a graphite negative electrode and a LiNi1/3Co1/3Mn1/3O2 positive electrode are assembled by in-situ chemical cross-linking, and their cycling performance is evaluated. The cells assembled with a reactive composite separator exhibit superior cycling performance to cell prepared with a conventional polyethylene separator due to the strong interfacial adhesion between the electrodes and separator, as well as suppression of deleterious reactions during cycling.

  8. Synthesis of internally functionalized silica nanoparticles for theranostic applications

    NASA Astrophysics Data System (ADS)

    Walton, Nathan Isaac

    This thesis addresses the synthesis and characterization of novel inorganic silica nanoparticle hybrids. It focuses in large part on their potential applications in the medical field. Silica acts as a useful carrier for a variety of compounds and this thesis silica will demonstrate its use as a carrier for boron or gadolinium. Boron-10 and gadolinium-157 have been suggested for the radiological treatment of tumor cells through the process called neutron capture therapy (NCT). Gadolinium is also commonly used as a Magnetic Resonance Imaging (MRI) contrast agent. Particles that carry it have potential theranostic applications of both imaging and treating tumors. Chapter 1 presents a background on synthetic strategies and usages of silica nanoparticles, and NCT theory. Chapter 2 describes a procedure to create mesoporous metal chelating silica nanoparticles, mDTTA. This is achieved via a co-condensation of tetraethoxysilane (TEOS) and 3-trimethoxysilyl-propyl diethylenetriamine (SiDETA) followed by a post-synthesis modification step with bromoacetic acid (BrAA). These particles have a large surface area and well-defined pores of ~2 nm. The mDTTA nanoparticles were used to chelate the copper(II), cobalt(II) and gadolinium(III). The chelating of gadolinium is the most interesting since it can be used as a MRI contrast agent and a neutron capture therapeutic. The synthetic procedure developed also allows for the attachment of a fluorophore that gives the gadolinium chelating mDTTA nanoparticles a dual imaging modality. Chapter 3 presents the synthetic method used to produce two classes of large surface area organically modified silica (ORMOSIL) nanoparticles. Condensating the organosilane vinyltrimethoxysilane in a micellar solution results in nanoparticles that are either surface rough (raspberry-like) or mesoporous nanoparticles, which prior to this thesis has not been demonstrated in ORMOSIL chemistry. Furthermore, the vinyl functionalities are modified, using

  9. New Indices of Endothelial Function Measured by Digital Thermal Monitoring of Vascular Reactivity: Data from 6084 Patients Registry.

    PubMed

    Naghavi, Morteza; Yen, Albert A; Lin, Alex W H; Tanaka, Hirofumi; Kleis, Stanley

    2016-01-01

    Background. Endothelial function is viewed as a barometer of cardiovascular health and plays a central role in vascular reactivity. Several studies showed digital thermal monitoring (DTM) as a simple noninvasive method to measure vascular reactivity that is correlated with atherosclerosis risk factors and coronary artery disease. Objectives. To further evaluate the relations between patient characteristics and DTM indices in a large patient registry. Methods. DTM measures were correlated with age, sex, heart rate, and systolic and diastolic blood pressure in 6084 patients from 18 clinics. Results. DTM vascular reactivity index (VRI) was normally distributed and inversely correlated with age (r = -0.21, p < 0.0001). Thirteen percent of VRI tests were categorized as poor vascular reactivity (VRI < 1.0), 70 percent as intermediate (1.0 ≤ VRI < 2.0), and 17 percent as good (VRI ≥ 2.0). Poor VRI (<1.0) was noted in 6% of <50 y, 10% of 50-70 y, and 18% of ≥70 y. In multiple linear regression analyses, age, sex, and diastolic blood pressure were significant but weak predictors of VRI. Conclusions. As the largest database of finger-based vascular reactivity measurement, this report adds to prior findings that VRI is a meaningful physiological marker and reflects a high level of residual risk found in patients currently under care.

  10. New Indices of Endothelial Function Measured by Digital Thermal Monitoring of Vascular Reactivity: Data from 6084 Patients Registry

    PubMed Central

    Yen, Albert A.; Lin, Alex W. H.; Tanaka, Hirofumi; Kleis, Stanley

    2016-01-01

    Background. Endothelial function is viewed as a barometer of cardiovascular health and plays a central role in vascular reactivity. Several studies showed digital thermal monitoring (DTM) as a simple noninvasive method to measure vascular reactivity that is correlated with atherosclerosis risk factors and coronary artery disease. Objectives. To further evaluate the relations between patient characteristics and DTM indices in a large patient registry. Methods. DTM measures were correlated with age, sex, heart rate, and systolic and diastolic blood pressure in 6084 patients from 18 clinics. Results. DTM vascular reactivity index (VRI) was normally distributed and inversely correlated with age (r = −0.21, p < 0.0001). Thirteen percent of VRI tests were categorized as poor vascular reactivity (VRI < 1.0), 70 percent as intermediate (1.0 ≤ VRI < 2.0), and 17 percent as good (VRI ≥ 2.0). Poor VRI (<1.0) was noted in 6% of <50 y, 10% of 50–70 y, and 18% of ≥70 y. In multiple linear regression analyses, age, sex, and diastolic blood pressure were significant but weak predictors of VRI. Conclusions. As the largest database of finger-based vascular reactivity measurement, this report adds to prior findings that VRI is a meaningful physiological marker and reflects a high level of residual risk found in patients currently under care. PMID:27830091

  11. Experimental and computational study on the reactivity of 2,3-bis[(3-pyridylmethyl)amino]-2(Z)-butene-1,4-dinitrile, a key intermediate for the synthesis of tribenzoporphyrazine bearing peripheral methyl(3-pyridylmethyl)amino substituents.

    PubMed

    Goslinski, Tomasz; Dutkiewicz, Zbigniew; Kryjewski, Michal; Tykarska, Ewa; Sobotta, Lukasz; Szczolko, Wojciech; Gdaniec, Maria; Mielcarek, Jadwiga

    An earlier developed alkylating path leading to tetraalkylated diaminomaleonitrile derivatives was explored. Attempts to explain the reactivity of the representative dialkylated diaminomaleonitrile 2,3-bis[(3-pyridylmethyl)amino]-2(Z)-butene-1,4-dinitrile during the alkylation reaction were performed using X-ray and density functional theory (DFT) studies. The condensed Fukui functions accompanied by softness indices were found to be useful in explaining its reactivity observed during the reaction. The values of the Fukui functions and condensed softness for electrophilic attack calculated from Mulliken, Löwdin, and natural population analyses closely corresponded to the experimental observations. When 2,3-bis[(3-pyridylmethyl)amino]-2(Z)-butene-1,4-dinitrile disodium salt was treated with dimethyl sulfate at lower temperatures the alkylation reaction prevailed, whereas at higher temperatures the alkylating agent acted as a hydride anion acceptor, which favored the elimination reaction. The tetraalkylated dinitrile 2,3-bis[methyl(3-pyridylmethyl)amino]-2(Z)-butene-1,4-dinitrile was used in the synthesis of tribenzoporphyrazine bearing methyl(3-pyridylmethyl)amino groups, which was subsequently subjected to solvatochromic and metallation studies. The changes observed during metallation seem to result from the coordination of the 3-pyridyl group by a palladium ion. This could influence the configuration of the methyl(3-pyridylmethyl)amino moiety, causing more effective donation of a lone pair of electrons from peripheral nitrogen to the macrocyclic ring. .

  12. Synthesis of redox-active molecules and their signaling functions during the expression of plant disease resistance.

    PubMed

    Skelly, Michael J; Loake, Gary J

    2013-09-20

    Activation of immune responses in plants is associated with a parallel burst of both reactive oxygen intermediates (ROIs) and nitric oxide (NO). The mechanisms by which these small redox-active molecules are synthesized and their signaling functions are critical for plants to defend themselves against pathogen infection. The synthesis of apoplastic ROIs by plants after pathogen recognition has long been attributed to membrane-bound NAPDH oxidases. However, the emerging data suggest a role for other enzymes in various subcellular locations in ROI production after defense activation. It is becoming widely appreciated that NO exerts its biochemical function through the S-nitrosylation of reactive cysteine thiols on target proteins, constituting a key post-translational modification. Recent evidence suggests that S-nitrosylation of specific defense-related proteins regulates their activity. The source(s) of NO production after pathogen recognition remain(s) poorly understood. Some NO synthesis can be attributed to the activity of nitrate reductase but to date, no nitric oxide synthase (NOS) has been identified in higher plants. However, the signaling functions of S-nitrosylation are becoming more apparent and thus dissecting the molecular machinery underpinning this redox-based modification is vital to further our understanding of plant disease resistance. In addition to identifying new contributors to the oxidative burst, the discovery of an NOS in higher plants would significantly move the field forward. Since S-nitrosylation has now been confirmed to play various roles in immune signaling, this redox-based modification is a potential target to exploit for improving disease resistance in crop species.

  13. Synthesis of nine-atom deltahedral Zintl ions of germanium and their functionalization with organic groups.

    PubMed

    Gillett-Kunnath, Miriam M; Sevov, Slavi C

    2012-02-11

    Although the first studies of Zintl ions date between the late 1890's and early 1930's they were not structurally characterized until many years later. Their redox chemistry is even younger, just about ten years old, but despite this short history these deltahedral clusters ions E9(n-) (E = Si, Ge, Sn, Pb; n = 2, 3, 4) have already shown interesting and diverse reactivity and have been at the forefront of rapidly developing and exciting new chemistry. Notable milestones are the oxidative coupling of Ge9(4-) clusters to oligomers and infinite chains, their metallation, capping by transition-metal organometallic fragments, insertion of a transition-metal atom at the center of the cluster which is sometimes combined with capping and oligomerization, addition of main-group organometallic fragments as exo-bonded substituents, and functionalization with various organic residues by reactions with organic halides and alkynes. This latter development of attaching organic fragments directly to the clusters has opened up a new field, namely organo-Zintl chemistry, that is potentially fertile for further synthetic explorations, and it is the step-by-step procedure for the synthesis of germanium-divinyl clusters described herein. The initial steps outline the synthesis of an intermetallic precursor of K4Ge9 from which the Ge9(4-) clusters are extracted later in solution. This involves fused-silica glass blowing, arc-welding of niobium containers, and handling of highly air-sensitive materials in a glove box. The air-sensitive K4Ge9 is then dissolved in ethylenediamine in the box and then alkenylated by a reaction with Me3SiC≡CSiMe3. The reaction is followed by electrospray mass spectrometry while the resulting solution is used for obtaining single crystals containing the functionalized clusters [H2C=CH-Ge9-CH=CH2](2-). For this purpose the solution is centrifuged, filtered, and carefully layered with a toluene solution of 18-crown-6. Left undisturbed for a few days, the so

  14. Synthesis of Nine-atom Deltahedral Zintl Ions of Germanium and their Functionalization with Organic Groups

    PubMed Central

    Gillett-Kunnath, Miriam M.; Sevov, Slavi C.

    2012-01-01

    Although the first studies of Zintl ions date between the late 1890's and early 1930's they were not structurally characterized until many years later.1,2 Their redox chemistry is even younger, just about ten years old, but despite this short history these deltahedral clusters ions E9n- (E = Si, Ge, Sn, Pb; n = 2, 3, 4) have already shown interesting and diverse reactivity and have been at the forefront of rapidly developing and exciting new chemistry.3-6 Notable milestones are the oxidative coupling of Ge94- clusters to oligomers and infinite chains,7-19 their metallation,14-16,20-25 capping by transition-metal organometallic fragments,26-34 insertion of a transition-metal atom at the center of the cluster which is sometimes combined with capping and oligomerization,35-47 addition of main-group organometallic fragments as exo-bonded substituents,48-50 and functionalization with various organic residues by reactions with organic halides and alkynes.51-58 This latter development of attaching organic fragments directly to the clusters has opened up a new field, namely organo-Zintl chemistry, that is potentially fertile for further synthetic explorations, and it is the step-by-step procedure for the synthesis of germanium-divinyl clusters described herein. The initial steps outline the synthesis of an intermetallic precursor of K4Ge9 from which the Ge94- clusters are extracted later in solution. This involves fused-silica glass blowing, arc-welding of niobium containers, and handling of highly air-sensitive materials in a glove box. The air-sensitive K4Ge9 is then dissolved in ethylenediamine in the box and then alkenylated by a reaction with Me3SiC≡CSiMe3. The reaction is followed by electrospray mass spectrometry while the resulting solution is used for obtaining single crystals containing the functionalized clusters [H2C=CH-Ge9-CH=CH2]2-. For this purpose the solution is centrifuged, filtered, and carefully layered with a toluene solution of 18-crown-6. Left

  15. State, not trait, neuroendocrine function predicts costly reactive aggression in men after social exclusion and inclusion.

    PubMed

    Geniole, Shawn N; Carré, Justin M; McCormick, Cheryl M

    2011-04-01

    Social exclusion increases aggressive behaviour, and the possible neuroendocrine underpinnings of the effect are largely unknown. Here, we examined the extent to which testosterone and cortisol responses to social exclusion would predict subsequent reactive aggression. Men were randomly assigned to a social exclusion (SE) or inclusion (SI) condition of 'Cyberball', a computer ball-toss game. Aggression was then measured using the Point Subtraction Aggression Paradigm (PSAP). Saliva was collected at three points for the measurement of testosterone and cortisol. Regression analyses indicated that testosterone concentrations 10-min into the PSAP (controlling for pre- and post-Cyberball testosterone) were positively correlated with aggressive behaviour, irrespective of SI/SE. Post hoc analyses for the conditions separately, however, suggested the relationship was stronger for SI men (R(2)(change)=13.3%, F(1,)(29)=5.28, p=0.03) than for SE men (R(2)(change)=1.8%, F(1,)(26)=0.49, p=0.49). Aggressive behaviour was also positively correlated with cortisol concentrations 10-min into the PSAP (controlling for pre- and post-Cyberball cortisol) irrespective of SE/SI. When both hormones were included in the regression model, the interaction of baseline 'Cortisol'×'Testosterone'×'Experimental Group' approached significance (R(2)(change)=5.4%, F(1,)(55)=3.53, p=0.07), but no significant effects were observed in either group alone. The findings add to evidence that individual differences in state neuroendocrine function map onto variability in human social behaviour. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Reactive Oxygen Species From Human Astrocytes Induced Functional Impairment and Oxidative Damage

    PubMed Central

    Sheng, Wen S; Hu, Shuxian; Feng, Amy; Rock, R. Bryan

    2013-01-01

    Reactive oxygen species (ROS) have been shown to be a contributor to aging and disease. ROS also serve as a trigger switch for signaling cascades leading to corresponding cellular and molecular events. In the central nervous system, microglial cells are likely the main source of ROS production. However, activated astrocytes also appear to be capable of generating ROS. In this study we investigated ROS production in human astrocytes stimulated with interleukin (IL)-1β and interferon (IFN)-γ and its potential harmful effects. Although IFN-γ alone had no effect, it potentiated IL-1β-induced ROS production in a time-dependent manner. One of the sources of ROS in IL-1β-activated astrocytes was from increased superoxide production in mitochondria accompanied by enhanced manganese superoxide dismutase and inhibited catalase expression. NADPH oxidase (NOX) may also contribute to ROS production as astrocytes express NOX isoforms. Glutamate uptake, which represents one of the most important methods of astrocytes to prevent excitotoxity, was down-regulated in IL-1β-activated astrocytes, and was further suppressed in the presence of IFN-γ; IFN-γ itself exerted minimal effect. Elevated levels of 8-isoprostane in IL-1β ± IFN-γ-activated human astrocytes indicate downstream lipid peroxidation. Pretreatment with DPI (diphenyleneiodonium) abolished the IL-1β ± IFN-γ-induced ROS production, restored glutamate uptake function and reduced 8-isoprostane to near control levels suggesting that ROS contributes to the dysfunction of activated astrocytes. These results support the notion that dampening activated human astrocytes to maintain the redox homeostasis is vital to preserve their neuroprotective potential in the CNS. PMID:23918204

  17. Sphingosine kinase functionally links elevated transmural pressure and increased reactive oxygen species formation in resistance arteries.

    PubMed

    Keller, Matthias; Lidington, Darcy; Vogel, Lukas; Peter, Bernhard Friedrich; Sohn, Hae-Young; Pagano, Patrick J; Pitson, Stuart; Spiegel, Sarah; Pohl, Ulrich; Bolz, Steffen-Sebastian

    2006-04-01

    Myogenic vasoconstriction, an intrinsic response to elevated transmural pressure (TMP), requires the activation of sphingosine kinase (Sk1) and the generation of reactive oxygen species (ROS). We hypothesized that pressure-induced Sk1 signaling and ROS generation are functionally linked. Using a model of cannulated resistance arteries isolated from the hamster gracilis muscle, we monitored vessel diameter and smooth muscle cell (SMC) Ca2+i (Fura-2) or ROS production (dichlorodihydrofluorescein). Elevation of TMP stimulated the translocation of a GFP-tagged Sk1 fusion protein from the cytosol to the plasma membrane, indicative of enzymatic activation. Concurrently, elevation of TMP initiated a rapid and transient production of ROS, which was enhanced by expression of wild-type Sk1 (hSk(wt)) and inhibited by its dominant-negative mutant (hSk(G82D)). Exogenous sphingosine-1-phosphate (S1P) also stimulated ROS generation is isolated vessels. Chemical (1 micromol/L DPI), peptide (gp91ds-tat/gp91ds), and genetic (N17Rac) inhibition strategies indicated that NADPH oxidase was the source of the pressure-induced ROS. NADPH oxidase inhibition attenuated myogenic vasoconstriction and reduced the apparent Ca2+ sensitivity of the SMC contractile apparatus, without affecting Ca2+-independent, RhoA-mediated vasoconstriction in response to exogenous S1P. Our results indicate a mandatory role for Sk1/S1P in mediating pressure-induced, NADPH oxidase-derived ROS formation. In turn, ROS generation appears to increase Ca2+ sensitivity, necessary for full myogenic vasoconstriction.

  18. Synthesis of functionalized fluorescent gold nanoclusters for acid phosphatase sensing

    NASA Astrophysics Data System (ADS)

    Sun, Jian; Yang, Fan; Yang, Xiurong

    2015-10-01

    A novel and convenient one-pot but two-step synthesis of fluorescent gold nanoclusters, incorporating glutathione (GSH) and 11-mercaptoundecanoic acid (MUA) as the functionalized ligands (i.e. AuNCs@GSH/MUA), is demonstrated. Herein, the mixing of HAuCl4 and GSH in aqueous solution results in the immediate formation of non-fluorescent GSH-Au+ complexes, and then a class of ~2.6 nm GSH-coated AuNCs (AuNCs@GSH) with mild orange-yellow fluorescence after several days. Interestingly, the intense orange-red emitting ~1.7 nm AuNCs@GSH/MUA can be synthesized within seconds by introducing an alkaline aqueous solution of MUA into the GSH-Au+ complexes or AuNC@GSH solution. Subsequently, a reliable AuNC@GSH/MUA-based real-time assay of acid phosphatase (ACP) is established for the first time, inspired by the selective coordination of Fe3+ with surface ligands of AuNCs, the higher binding affinity between the pyrophosphate ion (PPi) and Fe3+, and the hydrolysis of PPi into orthophosphate by ACP. Our fluorescent chemosensor can also be applied to assay ACP in a real biological sample and, furthermore, to screen the inhibitor of ACP. This report paves a new avenue for synthesizing AuNCs based on either the bottom-up reduction or top-down etching method, establishing real-time fluorescence assays for ACP by means of PPi as the substrate, and further exploring the sensing applications of fluorescent AuNCs.A novel and convenient one-pot but two-step synthesis of fluorescent gold nanoclusters, incorporating glutathione (GSH) and 11-mercaptoundecanoic acid (MUA) as the functionalized ligands (i.e. AuNCs@GSH/MUA), is demonstrated. Herein, the mixing of HAuCl4 and GSH in aqueous solution results in the immediate formation of non-fluorescent GSH-Au+ complexes, and then a class of ~2.6 nm GSH-coated AuNCs (AuNCs@GSH) with mild orange-yellow fluorescence after several days. Interestingly, the intense orange-red emitting ~1.7 nm AuNCs@GSH/MUA can be synthesized within seconds by

  19. [Plasma endotoxin, procalcitonin, C-reactive protein, and organ functions in patients with major burns].

    PubMed

    Ulrich, D; Noah, E M; Pallua, N

    2001-07-01

    Sepsis is one of the most frequent causes of death after major burn injury. Usually, sepsis appears as a consequence of a gram-negative bacteriaemia with release of endotoxins. In this study, the plasma endotoxin levels of seven patients (three female, four male; average age 51.3 +/- 23.8 years) with burns between 43.5 and 78 % Total Body Surface Area (Abbreviated Burn Severity Index 8 - 12) were determined for five days after thermal trauma every three hours by ELISA and compared with the concentration of procalcitonin (PCT) and C-reactive protein (CRP). A calculation of the Horrowitz-Index (PaO(2)/FiO(2)) and the Pressure-Adjusted Heart Rate (HR x CVP/MAP) took place to show a possible correlation between the endotoxin concentration and the cardiopulmonary organ function. Additionally, we analysed whether operative treatment can influence the level of plasma endotoxin in the early phase after burn injury. At any time after burn trauma, endotoxins could be detected in the plasma of all patients. Between the second and third day, there was a considerable increase in the endotoxin concentration with a maximum after 57 hours of 0.48 +/- 0.32 EU/ml. Two patients with sepsis and death in the further course had a rather distinctive increase. From the fourth day on, occasional episodes of increases in endotoxin concentration were noted. Postoperatively, there was a short increase in plasma endotoxin on the second and fourth day. The plasma endotoxin level showed no correlation with the PCT and CRP or with the oxygenation in the patients' blood. However, a positive correlation could be observed with the Pressure-Adjusted Heart Rate (p = 0.0061; r(2) = 0.212). An explanation for the endotoxin increase after 57 hours could be the translocation of intestinal bacteria, the beginning of bacterial colonisation or decomposition products of the burn wound with protein-protein complexes. Later on, infectious diseases such as pneumonia with gram-negative bacteria are of importance

  20. Synthesis of an end-group functionalized polyethylene glycol-lipid conjugate for preparation of polymer-grafted liposomes.

    PubMed

    Zalipsky, S

    1993-01-01

    Synthesis of a distearoylphosphatidylethanolamine-polyethylene glycol (DSPE-PEG) conjugate, bearing a hydrazide group at the unattached end of the polymer chain, was achieved using a new heterobifunctional polymeric reagent. The heterobifunctional PEG derivative carrying on one end a reactive succinimidyl carbonate (SC) group and at the other terminal a tert-butyloxycarbonyl (Boc) protected hydrazide group was prepared by an efficient four step process from readily available PEG-2000. The SC-end group of the polymer reacted readily with the amino group of DSPE forming a stable urethane attachment between lipid and PEG. Acidolytic removal of the Boc group yielded a hydrazide-PEG-lipid conjugate suitable for preparation of polymer-grafted liposomes. Taking advantage of the well-documented chemical versatility of hydrazide groups, various biologically relevant ligands can be linked to this type of functionalized liposomes.

  1. Surface reactivity of Ge[111] for organic functionalization by means of a radical-initiated reaction: A DFT study

    NASA Astrophysics Data System (ADS)

    Rubio-Pereda, Pamela; Takeuchi, Noboru

    2016-08-01

    The study of interfacial chemistry at semiconductor surfaces has become an important area of research. Functionalities such as molecular recognition, biocompatibility of surfaces, and molecular computing, could be achieved by the combinations of organic chemistry with the semiconductor technology. One way to accomplish this goal is by means of organic functionalization of semiconductor surfaces such as the bulk-terminated germanium surfaces, more specifically the Ge[111]. In this work, we theoretically study, by applying density functional theory, the surface reactivity of the bulk-terminated Ge[111] surface for organic functionalization by means of a radical-initiated reaction of unsaturated molecules such as acetylene, ethylene and styrene with a hydrogen vacancy on a previously hydrogen-terminated Ge[111] surface. Results derived from this work are compared with those obtained in our previous calculations on the germanene surface, following the same chemical route. Our calculations show an accumulation of electronic charge at the H-vacancy having as a result electron pairing due to strong lattice-electron coupling and therefore a diminished surface reactivity. Calculation of the transition states for acetylene and ethylene indicates that the surface reactivity of the hydrogen-terminated Ge[111] surface is less promising than its two-dimensional analogue, the hydrogen-terminated germanene.

  2. Baseline Functioning and Stress Reactivity in Maltreating Parents and At-Risk Adults

    PubMed Central

    Reijman, Sophie; Bakermans-Kranenburg, Marian J.; Hiraoka, Regina; Crouch, Julie L.; Milner, Joel S.; van IJzendoorn, Marinus H.

    2016-01-01

    We reviewed and meta-analyzed 10 studies (N = 492) that examined the association between (risk for) child maltreatment perpetration and basal autonomic activity, and 10 studies (N = 471) that examined the association between (risk for) child maltreatment and autonomic stress reactivity. We hypothesized that maltreating parents/at-risk adults would show higher basal levels of heart rate (HR) and skin conductance (SC) and lower levels of HR variability (HRV) and would show greater HR and SC stress reactivity, but blunted HRV reactivity. A narrative review showed that evidence from significance testing within and across studies was mixed. The first set of meta-analyses revealed that (risk for) child maltreatment was associated with higher HR baseline activity (g = 0.24), a possible indication of allostatic load. The second set of meta-analyses yielded no differences in autonomic stress reactivity between maltreating/at-risk participants and nonmaltreating/low-risk comparison groups. Cumulative meta-analyses showed that positive effects for sympathetic stress reactivity as a risk factor for child maltreatment were found in a few early studies, whereas each subsequently aggregated study reduced the combined effect size to a null effect, an indication of the winner’s curse. Most studies were underpowered. Future directions for research are suggested. PMID:27462035

  3. Design of a dinuclear nickel(II) bioinspired hydrolase to bind covalently to silica surfaces: synthesis, magnetism, and reactivity studies.

    PubMed

    Piovezan, Clovis; Silva, Jaqueline M R; Neves, Ademir; Bortoluzzi, Adailton J; Haase, Wolfgang; Tomkowicz, Zbigniew; Castellano, Eduardo E; Hough, Tessa C S; Rossi, Liane M

    2012-06-04

    Presented herein is the design of a dinuclear Ni(II) synthetic hydrolase [Ni(2)(HBPPAMFF)(μ-OAc)(2)(H(2)O)]BPh(4) (1) (H(2)BPPAMFF = 2-[(N-benzyl-N-2-pyridylmethylamine)]-4-methyl-6-[N-(2-pyridylmethyl)aminomethyl)])-4-methyl-6-formylphenol) to be covalently attached to silica surfaces, while maintaining its catalytic activity. An aldehyde-containing ligand (H(2)BPPAMFF) provides a reactive functional group that can serve as a cross-linking group to bind the complex to an organoalkoxysilane and later to the silica surfaces or directly to amino-modified surfaces. The dinuclear Ni(II) complex covalently attached to the silica surfaces was fully characterized by different techniques. The catalytic turnover number (k(cat)) of the immobilized Ni(II)Ni(II) catalyst in the hydrolysis of 2,4-bis(dinitrophenyl)phosphate is comparable to the homogeneous reaction; however, the catalyst interaction with the support enhanced the substrate to complex association constant, and consequently, the catalytic efficiency (E = k(cat)/K(M)) and the supported catalyst can be reused for subsequent diester hydrolysis reactions.

  4. Synthesis, solubilization, and surface functionalization of highly fluorescent quantum dots for cellular targeting through a small molecule

    NASA Astrophysics Data System (ADS)

    Galloway, Justin F.

    To achieve long-term fluorescence imaging with quantum dots (QDs), a CdSe core/shell must first be synthesized. The synthesis of bright CdSe QDs is not trivial and as a consequence, the role of surfactant in nucleation and growth was investigated. It was found that the type of surfactant used, either phosphonic or fatty acid, played a pivotal role in the size of the CdSe core. The study of surfactant on CdSe synthesis, ultimately led to an electrical passivation method that utilized a short-chained phosphonic acid and highly reactive organometallic precursors to achieve high quantum yield (QY) as has been previously described. The synthesis of QDs using organometallic precursors and a phosphonic acid for passivation resulted in 4 out of 9 batches of QDs achieving QYs greater than 50% and 8 out of 9 batches with QYs greater than 35%. The synthesis of CdSe QDs was done in organic solutions rendering the surface of the particle hydrophobic. To perform cell-targeting experiments, QDs must be transferred to water. The transfer of QDs to water was successfully accomplished by using single acyl chain lipids. A systematic study of different lipid combinations and coatings demonstrated that 20-40 mol% single acyl chained lipids were able to transfer QDs to water resulting in monodispersed, stable QDs without adversely affecting the QY. The advantage to water solubilization using single acyl chain lipids is that the QD have a hydrodynamic radius less than 15 nm, QYs that can exceed 50% and additional surface functionalization can be down using the reactive sites incorporated into the lipid bilayer. QDs that are bright and stable in water were studied for the purpose of targeting G protein-coupled Receptors (GPCR). GPCRs are transmembrane receptors that internalize extracellular cues, and thus mediate signal transduction. The cyclic Adenosine Monophosphate Receptor 1 of the model organism Dictyostelium disodium was the receptor of interest. The Halo protein, a genetically

  5. Chemically functionalized gold nanoparticles: Synthesis, characterization, and applications

    NASA Astrophysics Data System (ADS)

    Daniel, Weston Lewis

    This thesis focuses on the development and application of gold nanoparticle based detection systems and biomimetic structures. Each class of modified nanoparticle has properties that are defined by its chemical moieties that interface with solution and the gold nanoparticle core. In Chapter 2, a comparison of the biomolecular composition and binding properties of various preparations of antibody oligonucleotide gold nanoparticle conjugates is presented. These constructs differed significantly in terms of their structure and binding properties. Chapter 3 reports the use of electroless gold deposition as a light scattering signal enhancer in a multiplexed, microarray-based scanometric immunoassay using the gold nanoparticle probes evaluated in Chapter 2. The use of gold development results in greater signal enhancement than the typical silver development, and multiple rounds of metal development were found to increase the resulting signal compared to one development. Chapter 4 describes an amplified scanometric detection method for human telomerase activity. Gold nanoparticles functionalized with specific oligonucleotide sequences can efficiently capture telomerase enzymes and subsequently be elongated. Both the elongated and unmodified oligonucleotide sequences are simultaneously measured. At low telomerase concentrations, elongated strands cannot be detected, but the unmodified sequences, which come from the same probe particles, can be detected because their concentration is higher, providing a novel form of amplification. Chapter 5 reports the development of a novel colorimetric nitrite and nitrate ion assay based upon gold nanoparticle probes functionalized with Griess reaction reagents. This assay takes advantage of the distance-dependent plasmonic properties of the gold nanoparticles and the ability of nitrite ion to facilitate the cross coupling of novel nanoparticle probes. The assay works on the concept of a kinetic end point and can be triggered at the EPA

  6. Specificity, cross-reactivity, and function of antibodies elicited by Zika virus infection.

    PubMed

    Stettler, Karin; Beltramello, Martina; Espinosa, Diego A; Graham, Victoria; Cassotta, Antonino; Bianchi, Siro; Vanzetta, Fabrizia; Minola, Andrea; Jaconi, Stefano; Mele, Federico; Foglierini, Mathilde; Pedotti, Mattia; Simonelli, Luca; Dowall, Stuart; Atkinson, Barry; Percivalle, Elena; Simmons, Cameron P; Varani, Luca; Blum, Johannes; Baldanti, Fausto; Cameroni, Elisabetta; Hewson, Roger; Harris, Eva; Lanzavecchia, Antonio; Sallusto, Federica; Corti, Davide

    2016-08-19

    Zika virus (ZIKV), a mosquito-borne flavivirus with homology to Dengue virus (DENV), has become a public health emergency. By characterizing memory lymphocytes from ZIKV-infected patients, we dissected ZIKV-specific and DENV-cross-reactive immune responses. Antibodies to nonstructural protein 1 (NS1) were largely ZIKV-specific and were used to develop a serological diagnostic tool. In contrast, antibodies against E protein domain I/II (EDI/II) were cross-reactive and, although poorly neutralizing, potently enhanced ZIKV and DENV infection in vitro and lethally enhanced DENV disease in mice. Memory T cells against NS1 or E proteins were poorly cross-reactive, even in donors preexposed to DENV. The most potent neutralizing antibodies were ZIKV-specific and targeted EDIII or quaternary epitopes on infectious virus. An EDIII-specific antibody protected mice from lethal ZIKV infection, illustrating the potential for antibody-based therapy.

  7. In Situ Enrichment of Phosphopeptides on MALDI Plates Functionalized by Reactive Landing of Zirconium(IV)–n-Propoxide Ions

    PubMed Central

    Blacken, Grady R.; Volný, Michael; Vaisar, Tomáš; Sadílek, Martin; Tureček, František

    2008-01-01

    We report substantial in situ enrichment of phosphopeptides in peptide mixtures using zirconium oxide coated plates for detection by MALDI-TOF mass spectrometry. The novel feature of this approach rests on the specific preparation of zirconium oxide coatings using reactive landing on stainless steel support of gas-phase positive ions produced by electrospray of zirconium(IV)–n-propoxide solutions in 1-propanol. Reactive landing was found to produce durable functionalized surfaces for selective phosphopeptide capture and desorption–ionization by MALDI. Enrichment factors on the order of 20–90 were achieved for several monophosphorylated peptides relative to abundant nonphosphorylated peptides in tryptic digests. We demonstrate the ability of the zirconium oxide functionalized MALDI surfaces to facilitate detection of enriched phosphopeptides in mid-femtomole amounts of α-casein digests per MALDI spot. PMID:17569507

  8. Rheology at the Interface and the Role of the Interphase in Reactive Functionalized Multilayer Polymers in Coextrusion Process

    NASA Astrophysics Data System (ADS)

    Lamnawar, Khalid; Maazouz, Abderrahim

    2008-07-01

    Coextrusion technologies are commonly used to produce multilayered composite sheets or films for a large range of applications from food packaging to optics. The contrast of rheological properties between layers can lead to interfacial instabilities during flow. Important theoretical and experimental advances regarding the stability of compatible and incompatible polymers have, during the last decades, been made using a mechanical approach. However, few research efforts have been dedicated to the physicochemical affinity between the neighboring layers. The present study deals with the influence of this affinity on interfacial instabilities for functionalized incompatible polymers. Polyamide (PA6)/polyethylene grafted with glycidyl methacrylate (PE-GMA) was used as a reactive system and PE/PA6 as a non reactive one. Two grades of polyamide (PA6) were used in order to change the viscosity and elasticity ratios between PE (or PE-GMA) and PA6. It was experimentally confirmed, in this case, that weak disturbance can be predicted by considering an interphase of non-zero thickness (corresponding to an interdiffusion/reaction zone) instead of a purely geometrical interface between the two reactive layers. According to the rheological investigations from previous work which the interphase effect can be probed, an experimental strategy was here formulated to optimize the process by listing the parameters that controlled the stability of the reactive multilayer flows. Hence, based on this analysis, guidelines for a stable coextrusion of reactive functionalized polymers can be provided coupling the classical parameters (viscosity, elasticity and layer ratios) and the physicochemical affinity at the polymer/polymer interface.

  9. To each his own: isonitriles for all flavors. Functionalized isocyanides as valuable tools in organic synthesis.

    PubMed

    Giustiniano, Mariateresa; Basso, Andrea; Mercalli, Valentina; Massarotti, Alberto; Novellino, Ettore; Tron, Gian Cesare; Zhu, Jieping

    2017-03-06

    The term functionalized isocyanides refers to all those isocyanides in which a neighbouring functional group can finely tune the reactivity of the isocyano group or can be exploited in post-functionalization processes. In this manuscript, we have reviewed all the isocyanides in which the pendant functional group causes either deviation from or reinforces the normal reactivity of the isocyano group and categorized them to highlight their common features and differences. An analysis of their synthetic potential and the possible unexplored directions for future research studies is also addressed.

  10. Synthesis and structure of trinuclear W3S4 clusters bearing aminophosphine ligands and their reactivity toward halides and pseudohalides.

    PubMed

    Beltrán, Tomás F; Pino-Chamorro, Jose Ángel; Fernández-Trujillo, M Jesús; Safont, Vicent S; Basallote, Manuel G; Llusar, Rosa

    2015-01-20

    The aminophosphine ligand (2-aminoethyl)diphenylphosphine (edpp) has been coordinated to the W3(μ-S)(μ-S)3 cluster unit to afford trimetallic complex [W3S4Br3(edpp)3](+) (1(+)) in a one-step synthesis process with high yields. Related [W3S4X3(edpp)3](+) clusters (X = F(-), Cl(-), NCS(-); 2(+)-4(+)) have been isolated by treating 1(+) with the corresponding halide or pseudohalide salt. The structure of complexes 1(+) to 4(+) contains an incomplete W3S4 cubane-type cluster unit, and only one of the possible isomers is formed: the one with the phosphorus atoms trans to the capping sulfur and the amino groups trans to the bridging sulphurs. The remaining coordination position on each metal is occupied by X. Detailed studies using stopped-flow, (31)P{(1)H} NMR, and ESI-MS have been carried out in order to understand the solution behavior and the kinetics of interconversion among species 1(+), 2(+), 3(+), and 4(+) in solution. Density functional theory (DFT) calculations have been also carried out on the reactions of cluster 1(+) with the different anions. The whole set of experimental and theoretical data indicate that the actual mechanism of substitutions in these clusters is strongly dependent on the nature of the leaving and entering anions. The interaction between an entering F(-) and the amino group coordinated to the adjacent metal have also been found to be especially relevant to the kinetics of these reactions.

  11. Intrinsic platelet reactivity before start with clopidogrel as predictor for on-clopidogrel platelet function and long-term clinical outcome.

    PubMed

    Hochholzer, Willibald; Valina, Christian M; Bömicke, Timo; Amann, Michael; Stratz, Christian; Nührenberg, Thomas; Trenk, Dietmar; Neumann, Franz-Josef

    2015-07-01

    High on-clopidogrel platelet reactivity is associated with worse clinical outcome. Previous data suggest that intrinsic platelet reactivity before initiation of clopidogrel contributes significantly to on-clopidogrel platelet reactivity. It is unknown whether intrinsic reactivity can sufficiently predict on-clopidogrel reactivity and therefore identify patients with insufficient response to clopidogrel before initiation of treatment and at risk for worse clinical outcome. This analysis included 765 consecutive patients undergoing elective coronary stent implantation. Platelet reactivity was assessed by light transmission aggregometry (5 µM ADP) before administration of clopidogrel 600mg and after intake of first maintenance dose of clopidogrel on day 1 following coronary stenting. Patients were followed for up to seven years. The combined primary endpoint was death of any cause or non-fatal myocardial infarction. Intrinsic and on-clopidogrel platelet reactivity were significant correlated (r=0.31; p < 0.001). Among all tested clinical and genetic factors including the cytochrome P450 2C19*2 polymorphism, intrinsic platelet reactivity was the strongest predictor for on-clopidogrel platelet reactivity. However, intrinsic platelet reactivity could only explain 8 % of variability of on-clopidogrel platelet function. Only on-treatment platelet reactivity was predictive for long-term clinical outcome (HR 1.47, 95 % CI 1.05-2.05; p = 0.02) whereas intrinsic platelet reactivity was not (HR 1.03, 95 % CI 0.74-1.43; p = 0.86). In conclusion, intrinsic platelet reactivity before initiation of clopidogrel is the strongest predictor of early on-clopidogrel platelet reactivity but can only explain a minor proportion of its variability and is not significantly associated with clinical outcome. Thus, baseline testing cannot substitute on-clopidogrel platelet function testing.

  12. Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of Chalcogenidoplumbates(II or IV).

    PubMed

    Thiele, Günther; Donsbach, Carsten; Nußbruch, Isabell; Dehnen, Stefanie

    2016-12-29

    The phases of "PbCh2" (Ch = Se, Te) are obtained from solid-state syntheses (i.e., by the fusion of the elements under inert conditions in silica glass ampules). Reduction of such phases by elemental alkaline metals in amines affords crystalline chalcogenidoplumbate(II) salts comprised of [PbTe3](2)(-) or [Pb2Ch3](2)(-) anions, depending upon which sequestering agent for the cations is present: crown ethers, like 18-crown-6, or cryptands, like [2.2.2]crypt. Reactions of solutions of such anions with transition-metal compounds yield (poly-)chalcogenide anions or transition-metal chalcogenide clusters, including one with a µ-PbSe ligand (i.e., the heaviest-known CO homolog). In contrast, the solid-state synthesis of a phase of the nominal composition "K2PbSe2" by successive reactions of the elements and by the subsequent solvothermal treatment in amines yields the first non-oxide/halide inorganic lead(IV) compound: a salt of the ortho-selenidoplumbate(IV) anion [PbSe4](4)(-). This was unexpected due to the redox potentials of Pb(IV) and Se(-II). Such methods can further be applied to other elemental combinations, leading to the formation of solutions with binary [HgTe2](2)(-) or [BiSe3](3)(-) anions, or to large-scale syntheses of K2Hg2Se3 or K3BiSe3 via the solid-state route. All compounds are characterized by single-crystal X-ray diffraction and elemental analysis; solutions of plumbate salts can be investigated by (205)Pb and (77)Se or (127)Te NMR techniques. Quantum chemical calculations using density functional theory methods enable energy comparisons. They further allow for insights into the electronic configuration and thus, the bonding situation. Molecular Rh-containing Chevrel-type compounds were found to exhibit delocalized mixed valence, whereas similar telluridopalladate anions are electron-precise; the cluster with the µ-PbSe ligand is energetically favored over a hypothetical CO analog, in line with the unsuccessful attempt at its synthesis. The

  13. Synthesis of functionalized tetrasubstituted pyrazolyl heterocycles--a review.

    PubMed

    Dadiboyena, Sureshbabu; Nefzi, Adel

    2011-11-01

    Heterocyclic chemistry constitutes an essential branch of organic chemistry and heterocycles are widely known to display an array of biological properties. Pyrazoles represent key structural motifs in heterocyclic chemistry and are present in a large number of biologically active molecules relevant to the pharmaceutical and agrochemical industries. Compounds incorporating the pyrazolyl structural unit are being developed in a wide variety of therapeutic areas including CNS, metabolic diseases, and oncology. The current review summarizes recent advances in the synthesis of tetrasubstituted pyrazoles. The contents are discussed in five sections: (a) 1,3-dipolar cycloadditions, (b) related 1,3-dipolar cycloadditions, (c) condensations, (d) allenylphosphonates, and (e) synthesis of fused pyrazole containing heterocycles.

  14. Impulsivity, risk taking, and cortisol reactivity as a function of psychosocial stress and personality in adolescents.

    PubMed

    Finy, M Sima; Bresin, Konrad; Korol, Donna L; Verona, Edelyn

    2014-11-01

    Although adolescence is characterized by hormonal changes and increased disinhibited behaviors, explanations for these developmental changes that include personality and environmental factors have not been fully elucidated. We examined the interactions between psychosocial stress and the traits of negative emotionality and constraint on impulsive and risk-taking behaviors as well as salivary cortisol reactivity in 88 adolescents. In terms of behavioral outcomes, analyses revealed that negative emotionality and constraint were protective of impulsivity and risk taking, respectively, for adolescents in the no-stress condition; personality did not relate to either behavior in the stress condition. Low-constraint adolescents in the stress condition engaged in less risk taking than low-constraint adolescents in the no-stress condition, whereas there was no effect of stress group for high-constraint adolescents. In terms of cortisol reactivity, analyses revealed that low-constraint adolescents in the stress condition exhibited greater cortisol reactivity compared to high-constraint adolescents, which suggests that low-constraint adolescents mobilize greater resources (e.g., increased cognitive control, heightened attention to threat) in stressful situations relative to nonstressful ones. These results demonstrate that two facets of disinhibition and cortisol reactivity are differentially affected by psychosocial stress and personality (and their interactions) in adolescents.

  15. The Role of Emotional Responses and Physiological Reactivity in the Marital Conflict-Child Functioning Link

    ERIC Educational Resources Information Center

    El-Sheikh, Mona

    2005-01-01

    Background: Children's emotional responses and physiological reactivity to conflict were examined as mediators and moderators in the associations between exposure to parental marital conflict and child adjustment and cognitive problems. Method: One hundred and eighty elementary school children participated. In response to a simulated argument,…

  16. Mitochondrial function and reactive oxygen species action in relation to boar motility.

    USDA-ARS?s Scientific Manuscript database

    Flow cytometric assays of viable boar sperm were developed to measure reactive oxygen species (ROS) formation (oxidization of hydroethidine to ethidium), membrane lipid peroxidation (oxidation of lipophilic probe C11-BODIPY581/591), and mitochondrial inner transmembrane potential (aggregation of mit...

  17. Individual and Class Norms Differentially Predict Proactive and Reactive Aggression: A Functional Analysis

    ERIC Educational Resources Information Center

    Frey, Karin S.; Higheagle Strong, Zoe; Onyewuenyi, Adaurennaya C.

    2017-01-01

    Theory and research using a social-information processing framework indicate that reward-focused (proactive) aggression has different social consequences than defense-focused (reactive) aggression. Students use norms that identify expected and socially approved behaviors as guides to their own actions. Differences in social-cognitive processing…

  18. Individual and Class Norms Differentially Predict Proactive and Reactive Aggression: A Functional Analysis

    ERIC Educational Resources Information Center

    Frey, Karin S.; Higheagle Strong, Zoe; Onyewuenyi, Adaurennaya C.

    2017-01-01

    Theory and research using a social-information processing framework indicate that reward-focused (proactive) aggression has different social consequences than defense-focused (reactive) aggression. Students use norms that identify expected and socially approved behaviors as guides to their own actions. Differences in social-cognitive processing…

  19. Effects of reactive oxygen species action on sperm function in spermatozoa

    USDA-ARS?s Scientific Manuscript database

    Reactive oxygen species (ROS) formation and lipid peroxidation have been recognized as problems for sperm survival and fertility. The precise roles and detection of superoxide (SO), hydrogen peroxide (HP), and membrane lipid peroxidation have been problematic because of the low specificity and sens...

  20. Thioredoxin-2 inhibits mitochondrial reactive oxygen species generation and apoptosis stress kinase-1 activity to maintain cardiac function.

    PubMed

    Huang, Qunhua; Zhou, Huanjiao Jenny; Zhang, Haifeng; Huang, Yan; Hinojosa-Kirschenbaum, Ford; Fan, Peidong; Yao, Lina; Belardinelli, Luiz; Tellides, George; Giordano, Frank J; Budas, Grant R; Min, Wang

    2015-03-24

    Thioredoxin 2 (Trx2) is a key mitochondrial protein that regulates cellular redox and survival by suppressing mitochondrial reactive oxygen species generation and by inhibiting apoptosis stress kinase-1 (ASK1)-dependent apoptotic signaling. To date, the role of the mitochondrial Trx2 system in heart failure pathogenesis has not been investigated. Western blot and histological analysis revealed that Trx2 protein expression levels were reduced in hearts from patients with dilated cardiomyopathy, with a concomitant increase in ASK1 phosphorylation/activity. Cardiac-specific Trx2 knockout mice develop spontaneous dilated cardiomyopathy at 1 month of age with increased heart size, reduced ventricular wall thickness, and a progressive decline in left ventricular contractile function, resulting in mortality due to heart failure by ≈4 months of age. The progressive decline in cardiac function observed in cardiac-specific Trx2 knockout mice was accompanied by the disruption of mitochondrial ultrastructure, mitochondrial membrane depolarization, increased mitochondrial reactive oxygen species generation, and reduced ATP production, correlating with increased ASK1 signaling and increased cardiomyocyte apoptosis. Chronic administration of a highly selective ASK1 inhibitor improved cardiac phenotype and reduced maladaptive left ventricular remodeling with significant reductions in oxidative stress, apoptosis, fibrosis, and cardiac failure. Cellular data from Trx2-deficient cardiomyocytes demonstrated that ASK1 inhibition reduced apoptosis and reduced mitochondrial reactive oxygen species generation. Our data support an essential role for mitochondrial Trx2 in preserving cardiac function by suppressing mitochondrial reactive oxygen species production and ASK1-dependent apoptosis. Inhibition of ASK1 represents a promising therapeutic strategy for the treatment of dilated cardiomyopathy and heart failure. © 2015 American Heart Association, Inc.

  1. Experimental investigation of aminoacetonitrile formation through the Strecker synthesis in astrophysical-like conditions: reactivity of methanimine (CH2NH), ammonia (NH3), and hydrogen cyanide (HCN)

    NASA Astrophysics Data System (ADS)

    Danger, G.; Borget, F.; Chomat, M.; Duvernay, F.; Theulé, P.; Guillemin, J.-C.; Le Sergeant D'Hendecourt, L.; Chiavassa, T.

    2011-11-01

    Context. Studing chemical reactivity in astrophysical environments is an important means for improving our understanding of the origin of the organic matter in molecular clouds, in protoplanetary disks, and possibly, as a final destination, in our solar system. Laboratory simulations of the reactivity of ice analogs provide important insight into the reactivity in these environments. Here, we use these experimental simulations to investigate the Strecker synthesis leading to the formation of aminoacetonitrile in astrophysical-like conditions. The aminoacetonitrile is an interesting compound because it was detected in SgrB2, hence could be a precursor of the smallest amino acid molecule, glycine, in astrophysical environments. Aims: We present the first experimental investigation of the formation of aminoacetonitrile NH2CH2CN from the thermal processing of ices including methanimine (CH2NH), ammonia (NH3), and hydrogen cyanide (HCN) in interstellar-like conditions without VUV photons or particules. Methods: We use Fourier Transform InfraRed (FTIR) spectroscopy to monitor the ice evolution during its warming. Infrared spectroscopy and mass spectroscopy are then used to identify the aminoacetonitrile formation. Results: We demonstrate that methanimine can react with -CN during the warming of ice analogs containing at 20 K methanimine, ammonia, and [NH4+ -CN] salt. During the ice warming, this reaction leads to the formation of poly(methylene-imine) polymers. The polymer length depend on the initial ratio of mass contained in methanimine to that in the [NH4+ -CN] salt. In a methanimine excess, long polymers are formed. As the methanimine is progressively diluted in the [NH4+ -CN] salt, the polymer length decreases until the aminoacetonitrile formation at 135 K. Therefore, these results demonstrate that aminoacetonitrile can be formed through the second step of the Strecker synthesis in astrophysical-like conditions.

  2. Data synthesis and display programs for wave distribution function analysis

    NASA Technical Reports Server (NTRS)

    Storey, L. R. O.; Yeh, K. J.

    1992-01-01

    At the National Space Science Data Center (NSSDC) software was written to synthesize and display artificial data for use in developing the methodology of wave distribution analysis. The software comprises two separate interactive programs, one for data synthesis and the other for data display.

  3. Structure and functionalities of the human c-reactive protein compared to the zebrafish multigene family of c-reactive-like proteins.

    PubMed

    Bello-Perez, Melissa; Falco, Alberto; Medina, Regla; Encinar, Jose Antonio; Novoa, Beatriz; Perez, Luis; Estepa, Amparo; Coll, Julio

    2017-04-01

    Because of the recent discovery of multiple c-reactive protein (crp)-like genes in zebrafish (Danio rerio) with predicted heterogeneous phospholipid-binding amino acid sequences and heterogeneous transcript expression levels in viral survivors and adaptive-deficient mutants, zebrafish constitute an attractive new model for exploring the evolution of these protein's functions, including their possible participation in fish trained immunity. Circulating human CRP belongs to the short pentraxin family of oligomeric proteins that are characteristic of early acute-phase innate responses and is widely used as a clinical inflammation marker. In contrast to pentameric human CRP (pCRP), zebrafish CRPs are trimeric (tCRP); however monomeric CRP (mCRP) conformations may also be generated when associated with cellular membranes as occurs in humans. Compared to human CRP, zebrafish CRP-like proteins show homologous amino acid sequence stretches that are consistent with, although not yet demonstrated, cysteine-dependent redox switches, calcium-binding spots, phosphocholine-binding pockets, C1q-binding domains, regions interacting with immunoglobulin Fc receptors (FcR), unique mCRP epitopes, mCRP binding peptides to cholesterol-enriched rafts, protease target sites, and/or binding sites to monocyte, macrophage, neutrophils, platelets and/or endothelial cells. Amino acid variations among the zebrafish CRP-like multiprotein family and derived isoforms in these stretches suggest that functional heterogeneity best fits the wide variety of aquatic pathogens. As occurs in humans, phospholipid-tagged tCRP-like multiproteins might also influence local inflammation and induce innate immune responses; however, in addition, different zebrafish tCRP-like proteins and/or isoforms might fine tune new still unknown functions. The information reviewed here could be of value for future studies not only to comparative but also medical immunologists and/or fisheries sectors. This review also

  4. Global and local reactivity of simple substituted nitrenes and phosphinidenes within the spin-polarized density functional theory framework

    NASA Astrophysics Data System (ADS)

    Rincón, Elizabeth; Pérez, Patricia; Chamorro, Eduardo

    2007-11-01

    The local reactivity proclivities in a series of simple substituted nitrenes (N-X) and phosphinidenes (P-X) have been explored for the lowest-lying singlet and triplet electronic states within the framework of spin-polarized density functional theory (SP-DFT). Linear correlations have been found between both the global and local philicities for spin polarization and the vertical singlet-triplet energy gaps. The accumulation and depletion of the electron or spin density can be directly related to the electronegativity of the substituent atoms. The local analysis has been achieved on the basis of a recent implementation of condensed-to-site SP-DFT Fukui functions.

  5. Role of fatty-acid synthesis in dendritic cell generation and function.

    PubMed

    Rehman, Adeel; Hemmert, Keith C; Ochi, Atsuo; Jamal, Mohsin; Henning, Justin R; Barilla, Rocky; Quesada, Juan P; Zambirinis, Constantinos P; Tang, Kerry; Ego-Osuala, Melvin; Rao, Raghavendra S; Greco, Stephanie; Deutsch, Michael; Narayan, Suchithra; Pachter, H Leon; Graffeo, Christopher S; Acehan, Devrim; Miller, George

    2013-05-01

    Dendritic cells (DC) are professional APCs that regulate innate and adaptive immunity. The role of fatty-acid synthesis in DC development and function is uncertain. We found that blockade of fatty-acid synthesis markedly decreases dendropoiesis in the liver and in primary and secondary lymphoid organs in mice. Human DC development from PBMC precursors was also diminished by blockade of fatty-acid synthesis. This was associated with higher rates of apoptosis in precursor cells and increased expression of cleaved caspase-3 and BCL-xL and downregulation of cyclin B1. Further, blockade of fatty-acid synthesis decreased DC expression of MHC class II, ICAM-1, B7-1, and B7-2 but increased their production of selected proinflammatory cytokines including IL-12 and MCP-1. Accordingly, inhibition of fatty-acid synthesis enhanced DC capacity to activate allogeneic as well as Ag-restricted CD4(+) and CD8(+) T cells and induce CTL responses. Further, blockade of fatty-acid synthesis increased DC expression of Notch ligands and enhanced their ability to activate NK cell immune phenotype and IFN-γ production. Because endoplasmic reticulum (ER) stress can augment the immunogenic function of APC, we postulated that this may account for the higher DC immunogenicity. We found that inhibition of fatty-acid synthesis resulted in elevated expression of numerous markers of ER stress in humans and mice and was associated with increased MAPK and Akt signaling. Further, lowering ER stress by 4-phenylbutyrate mitigated the enhanced immune stimulation associated with fatty-acid synthesis blockade. Our findings elucidate the role of fatty-acid synthesis in DC development and function and have implications to the design of DC vaccines for immunotherapy.

  6. Role of Fatty-acid Synthesis in Dendritic Cell Generation and Function

    PubMed Central

    Rehman, Adeel; Hemmert, Keith C.; Ochi, Atsuo; Jamal, Mohsin; Henning, Justin R.; Barilla, Rocky; Quesada, Juan P.; Zambirinis, Constantinos P.; Tang, Kerry; Ego-Osuala, Melvin; Rao, Raghavendra S.; Greco, Stephanie; Deutsch, Michael; Narayan, Suchithra; Pachter, H. Leon; Graffeo, Christopher S.; Acehan, Devrim; Miller, George

    2013-01-01

    Dendritic cells (DC) are professional antigen presenting cells that regulate innate and adaptive immunity. The role of fatty-acid synthesis in DC development and function is uncertain. We found that blockade of fatty-acid synthesis markedly decreases dendropoiesis in the liver and in primary and secondary lymphoid organs in mice. Human DC development from PBMC precursors was also diminished by blockade of fatty-acid synthesis. This was associated with higher rates of apoptosis in precursor cells and increased expression of Cleaved Caspase 3 and BCL-xL, and down-regulation of Cyclin B1. Further, blockade of fatty-acid synthesis decreased DC expression of MHCII, ICAM-1, B7-1, B7-2 but increased their production of selected pro-inflammatory cytokines including IL-12 and MCP-1. Accordingly, inhibition of fatty-acid synthesis enhanced DC capacityto activate allogeneic as well as antigen-restricted CD4+ and CD8+ T cells and induce CTL responses. Further, blockade of fatty-acid synthesis increased DC expression of Notch ligands and enhanced their ability to activate NK cell immune-phenotype and IFN-γ production. Since endoplasmic reticular (ER)-stress can augment the immunogenic function of APC, we postulated that this may account for the higher DC immunogenicity. We found that inhibition of fatty-acid synthesis resulted in elevated expression of numerous markers of ER stress in humans and mice and was associated with increased MAP kinase and Akt signaling. Further, lowering ER-stress by 4-phenylbutyrate mitigated the enhanced immune-stimulation associated with fatty-acid synthesis blockade. Our findings elucidate the role of fatty-acid synthesis in DC development and function and have implications to the design of DC vaccines for immunotherapy. PMID:23536633

  7. Surface decoration through electrostatic interaction leading to enhanced reactivity: Low temperature synthesis of nanostructured chromium borides (CrB and CrB{sub 2})

    SciTech Connect

    Menaka,; Kumar, Bharat; Kumar, Sandeep; Ganguli, A.K.

    2013-04-15

    The present study describes a novel low temperature route at ambient pressure for the synthesis of nanocrystalline chromium borides (CrB and CrB{sub 2}) without using any flux or additives. The favorable and intimate mixing of nanoparticles of chromium acetate (Cr source) and boron forms an active chromium–boron precursor which decomposes at much lower temperature (400 °C) to form CrB (which is ∼1000 °C less than the known ambient pressure synthesis). The chromium acetate nanoparticles (∼5 nm) decorate the larger boron particles (150–200 nm) due to electrostatic interactions resulting from opposing surface charges of boron (zeta potential:+48.101 mV) and chromium acetate (zeta potential:−4.021 mV) in ethanolic medium and is evident in the TEM micrographs. The above method leads to the formation of pure CrB film like structure at 400 °C and nanospheres (40–60 nm) at 600 °C. Also, chromium diboride (CrB{sub 2}) nanoparticles (25 nm) could be obtained at 1000 °C. - Graphical abstract: Variation of surface charge of reactants, precursor and the products, chromium borides (CrB and CrB{sub 2}). Highlights: ► Novel borothermal reduction process for synthesis of chromium boride. ► Significant lowering of reaction temperature to obtain nanocrystalline chromium boride. ► Enhanced reactivity due to appropriate surface interactions.

  8. Development of new methods in modern selective organic synthesis: preparation of functionalized molecules with atomic precision

    NASA