WorldWideScience

Sample records for surface carboxylate groups

  1. Enrichment of Nanodiamond Surfaces with Carboxyl Groups for Doxorubicin Loading and Release

    Science.gov (United States)

    Astuti, Y.; Saputra, F. D.; Wuning, S.; Arnelli; Bhaduri, G.

    2017-02-01

    In their pristine state, nanodiamond crystals produced via detonation techniques containing several functional groups present on the surface including amine, amide, alcohol, carbonyl, and carboxyl. These functional groups facilitate nanodiamond to interact drugs so as to nanodiamond is potential for medical application such as drug delivery. Even though research on t he use of nanodiamond for this application has been conducted widely, research on the effect of enrichment of nanodiamond surface with carboxyl functional groups for drug loading and release has not been explored extensively. Therefore, in this paper, the effect of carboxyl-terminated nanodiamond (ND-COOH) on drug loading and release will be presented. The enrichment of nanodiamond with carboxyl groups was undertaken by treating nanodiamond with sulphuric acid and nitric acid. The results show that the doxorubicin (DOX) loading and release efficiencies of ND pristine are higher than that of ND-COOH.

  2. Controlled surface functionalization of silica-coated magnetic nanoparticles with terminal amino and carboxyl groups

    International Nuclear Information System (INIS)

    Kralj, Slavko; Drofenik, Miha; Makovec, Darko

    2011-01-01

    General and versatile methods for the functionalization of superparamagnetic, silica-coated, maghemite nanoparticles by surface amino and/or carboxyl groups have been established. The nanoparticles were synthesized using co-precipitation from aqueous solutions and coated with a thin layer of silica using the hydrolysis and condensation of tetraethoxysilane (TEOS). For the amino functionalization, 3-(2-aminoethylamino)propylmethyldimethoxysilane (APMS) was grafted onto the nanoparticle surfaces in their aqueous suspensions. The grafting process was followed by measurements of the ζ-potential and a determination of the concentration of the surface amino groups with conductometric titrations. The surface concentration of the amino groups could be varied by increasing the amount of APMS in the grafting process up to approximately 2.3 –NH 2 groups per nm 2 . The carboxyl functionalization was obtained in two ways: (i) by a ring-opening linker elongation reaction of the surface amines at the functionalized nanoparticles with succinic anhydride (SA) in non-aqueous medium, and (ii) by reacting the APMS and SA first, followed by grafting of the carboxyl-terminated reagent onto the nanoparticle surfaces. Using the first method, the SA only reacted with the terminal primary amino groups (–NH 2 ) of the surface-grafted APMS molecules. Infra-red spectroscopy (ATR FTIR) and mass spectrometry (HRMS) showed that the second method enables the bonding of up to two SA molecules per one APMS molecule, since the SA reacted with both the primary (–NH 2 ) and secondary amino (–NH–) groups of the APMS molecule. When using both methods, the ratio between the surface amino and carboxyl groups can be controlled.

  3. Influence of carboxyl group formation on ammonia adsorption of NiO-templated nanoporous carbon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Long-Yue [Department of Chemistry, Inha University, 100 Inharo, Nam-gu, Incheon 402-751 (Korea, Republic of); Park, Soo-Jin, E-mail: sjpark@inha.ac.kr [Department of Chemistry, Inha University, 100 Inharo, Nam-gu, Incheon 402-751 (Korea, Republic of)

    2012-11-15

    The scope of this work was to control the surface functional groups of nanoporous carbons (NPs) by oxidizing agents (nitric acid and hydrogen peroxide) treatments and to investigate the relation between carboxyl group and ammonia removal efficiency. The NPs were directly prepared from a cation exchange resin by the carbonization of a mixture with Ni acetate at 900 Degree-Sign C. N{sub 2}/-196 Degree-Sign C adsorption, Boehm's titrations, and X-ray photoelectron spectroscopy (XPS) analyzes were employed to confirm the physicochemical properties of NPs. The ammonia removal efficiency was confirmed by temperature programmed desorption (TPD) technique. In the result, the oxygen content of NPs increased after various treatments and the highest content of carboxyl group formation appeared at a 2:3 volume ratio of HNO{sub 3}/H{sub 2}O{sub 2}. It was also found that the oxidation treatment led to an increase in ammonia removal efficiency of NPs, mainly due to an increase of acid oxygen functional groups (such as carboxyl) on NPs surfaces. -- Graphical abstract: The nanoporous carbons were prepared from an exchange resin by the carbonization of a mixture with Ni acetate for ammonia adsorption. Highlights: Black-Right-Pointing-Pointer The carbons were prepared from an exchange resin by the carbonization of a mixture with Ni acetate. Black-Right-Pointing-Pointer The carbon surfaces were modified with HNO{sub 3}/H{sub 2}O{sub 2} solution at different volume radio. Black-Right-Pointing-Pointer The highest content of carboxyl group formation appeared at a 2:3 volume ratio of HNO{sub 3}/H{sub 2}O{sub 2}. Black-Right-Pointing-Pointer The acid oxygen functional groups (such as carboxyl) on carbon surfaces led to an increase in ammonia adsorption.

  4. Coupling of carboxylic groups onto the surface of polystyrene parts during fused filament fabrication

    Science.gov (United States)

    Nagel, Jürgen; Zimmermann, Philipp; Schubert, Oliver; Simon, Frank; Schlenstedt, Kornelia

    2017-11-01

    A method for the fabrication of polystyrene parts, modified with carboxylic groups during Fused Filament Fabrication (FFF), is being introduced. This method is based on the application of a thin layer of a reactive polymer carrying carboxylic groups on a substrate surface. A polystyrene film is printed on top of this layer. During contact between the hot melt and the reactive layer, a Friedel-Crafts type acylation using a green catalyst takes place, which attaches the reactive polymer to the polystyrene surface. The modified surface is homogeneous, hydrophilic and able to bind copper ions. The method could be used to fabricate unique parts of polystyrene with tailored surface functionalisation. It could be applied for laboratory use, e.g. for the manufacture of lab-on-a-chip devices.

  5. Surface grafting of carboxylic groups onto thermoplastic polyurethanes to reduce cell adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Alves, P., E-mail: palves@eq.uc.pt [CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra (Portugal); Ferreira, P. [CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra (Portugal); Kaiser, Jean-Pierre [EMPA, St. Gallen, Lerchenfeldstrasse 5, CH-9014 St. Gallen (Switzerland); Salk, Natalie [Mikrofertigung – Micro Engineering, Fraunhofer IFAM, Wiener Strasse 12, D-288359 Bremen (Germany); Bruinink, Arie [EMPA, St. Gallen, Lerchenfeldstrasse 5, CH-9014 St. Gallen (Switzerland); Sousa, Hermínio C. de; Gil, M.H. [CIEPQPF, Departamento de Engenharia Química, Universidade de Coimbra, Polo II, Pinhal de Marrocos, 3030-790 Coimbra (Portugal)

    2013-10-15

    The interaction of polymers with other materials is an important issue, being their surface properties clearly crucial. For some important polymer applications, their surfaces have to be modified. Surface modification aims to tailor the surface characteristics of a material for a specific application without affecting its bulk properties. Materials can be surface modified by using biological, chemical or physical methods. The aim of this work was to improve the reactivity of the thermoplastic polyurethane (TPU) material (Elastollan{sup ®}) surface and to make its surface cell repellent by grafting carboxylic groups onto its surface. Two TPU materials were studied: a polyether-based TPU and a polyester-based TPU. The grafting efficiency was evaluated by contact angle measurements and by analytical determination of the COOH groups. Scanning electron microscopy (SEM) of the membranes surface was performed as well as cell adhesion tests. It was proved that the surfaces of the TPUs membranes were successfully modified and that cell adhesion was remarkably reduced.

  6. Acid-Base Behavior of Carboxylic Acid Groups Covalently Attached at the Surface of Polyethylene: The Usefulness of Contact Angle in Following the Ionization of Surface Functionality

    Science.gov (United States)

    1985-08-01

    additional check, we converted granular PE-CO 2H to granular PE-CO 2CH3 by acid -catalyzed esterification. This material had no titrable groups. Upon...Task No. NR-631-840 TECHNICAL REPORT NO. 85-1 Acid -Base Behavior of Carboxylic Acid Groups Covalently Attached at the Surface of Polyethylene: The...34I Acid -Base Behavior K-142 ofCarboxylicAcidGroupsAttached...______________________ 12. PERSIIMAL AUTHOR IS) S.R. Holmes-Farly., R.H. Reamey, T.J

  7. Carboxyl group reactivity in actin

    Energy Technology Data Exchange (ETDEWEB)

    Elzinga, M.

    1986-01-01

    While earlier work showed that the carboxyl groups of proteins could be quantitatively coupled to amino groups at pH 4.75 in the presence of EDC and a denaturing agent, the work presented here indicates that under milder conditions the modification of sidechain carboxyls is limited and somewhat specific. Most of the incorporated glycine ethyl ester (GEE) is apparently bound to five carboxyls. The total GEE incorporated was 3 to 4 moles/mole of protein as measured by an increase in Gly upon acid hydrolysis and amino acid analysis, as well as total radioactivity. 3.55 residues were found in peptides, 2.75 bound to residues 1 to 4, and 0.8 bound to Gly-100. 9 refs., 2 figs., 2 tabs.

  8. Carboxyl group reactivity in actin

    International Nuclear Information System (INIS)

    Elzinga, M.

    1986-01-01

    While earlier work showed that the carboxyl groups of proteins could be quantitatively coupled to amino groups at pH 4.75 in the presence of EDC and a denaturing agent, the work presented here indicates that under milder conditions the modification of sidechain carboxyls is limited and somewhat specific. Most of the incorporated glycine ethyl ester (GEE) is apparently bound to five carboxyls. The total GEE incorporated was 3 to 4 moles/mole of protein as measured by an increase in Gly upon acid hydrolysis and amino acid analysis, as well as total radioactivity. 3.55 residues were found in peptides, 2.75 bound to residues 1 to 4, and 0.8 bound to Gly-100. 9 refs., 2 figs., 2 tabs

  9. Polymethyl methacrylate-co-methacrylic acid coatings with controllable concentration of surface carboxyl groups: A novel approach in fabrication of polymeric platforms for potential bio-diagnostic devices

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, Samira; Ibrahim, Fatimah [Center for Innovation in Medical Engineering, Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Djordjevic, Ivan, E-mail: ivan.djordjevic@um.edu.my [Center for Innovation in Medical Engineering, Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Koole, Leo H. [Center for Innovation in Medical Engineering, Department of Biomedical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603 (Malaysia); Department of Biomedical Engineering, Faculty of Health. Medicine and Life Science, Maastricht University, PO Box 616, NL 6200 MD Maastricht (Netherlands)

    2014-05-01

    Highlights: • Synthesis and processing of PMMA-co-MAA spin-coatings on silicon wafers. • Surface chemistry and morphology as a function of tailored co-polymer structure. • Polymer coatings with controlled number of surface carboxyl groups. - Abstract: The generally accepted strategy in development of bio-diagnostic devices is to immobilize proteins on polymeric surfaces as a part of detection process for diseases and viruses through antibody/antigen coupling. In that perspective, polymer surface properties such as concentration of functional groups must be closely controlled in order to preserve the protein activity. In order to improve the surface characteristics of transparent polymethacrylate plastics that are used for diagnostic devices, we have developed an effective fabrication procedure of polymethylmetacrylate-co-metacrylic acid (PMMA-co-MAA) coatings with controlled number of surface carboxyl groups. The polymers were processed effectively with the spin-coating technique and the detailed control over surface properties is here by demonstrated through the variation of a single synthesis reaction parameter. The chemical structure of synthesized and processed co-polymers has been investigated with nuclear magnetic resonance spectroscopy (NMR) and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-ToF-MS). The surface morphology of polymer coatings have been analyzed with atomic force microscopy (AFM) and scanning electron microscopy (SEM). We demonstrate that the surface morphology and the concentration of surface –COOH groups (determined with UV–vis surface titration) on the processed PMMA-co-MAA coatings can be precisely controlled by variation of initial molar ratio of reactants in the free-radical polymerization reaction. The wettability of developed polymer surfaces also varies with macromolecular structure.

  10. Polymethyl methacrylate-co-methacrylic acid coatings with controllable concentration of surface carboxyl groups: A novel approach in fabrication of polymeric platforms for potential bio-diagnostic devices

    International Nuclear Information System (INIS)

    Hosseini, Samira; Ibrahim, Fatimah; Djordjevic, Ivan; Koole, Leo H.

    2014-01-01

    Highlights: • Synthesis and processing of PMMA-co-MAA spin-coatings on silicon wafers. • Surface chemistry and morphology as a function of tailored co-polymer structure. • Polymer coatings with controlled number of surface carboxyl groups. - Abstract: The generally accepted strategy in development of bio-diagnostic devices is to immobilize proteins on polymeric surfaces as a part of detection process for diseases and viruses through antibody/antigen coupling. In that perspective, polymer surface properties such as concentration of functional groups must be closely controlled in order to preserve the protein activity. In order to improve the surface characteristics of transparent polymethacrylate plastics that are used for diagnostic devices, we have developed an effective fabrication procedure of polymethylmetacrylate-co-metacrylic acid (PMMA-co-MAA) coatings with controlled number of surface carboxyl groups. The polymers were processed effectively with the spin-coating technique and the detailed control over surface properties is here by demonstrated through the variation of a single synthesis reaction parameter. The chemical structure of synthesized and processed co-polymers has been investigated with nuclear magnetic resonance spectroscopy (NMR) and matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-ToF-MS). The surface morphology of polymer coatings have been analyzed with atomic force microscopy (AFM) and scanning electron microscopy (SEM). We demonstrate that the surface morphology and the concentration of surface –COOH groups (determined with UV–vis surface titration) on the processed PMMA-co-MAA coatings can be precisely controlled by variation of initial molar ratio of reactants in the free-radical polymerization reaction. The wettability of developed polymer surfaces also varies with macromolecular structure

  11. Electrical properties of SAM-modified ITO surface using aromatic small molecules with double bond carboxylic acid groups for OLED applications

    International Nuclear Information System (INIS)

    Can, Mustafa; Havare, Ali Kemal; Aydın, Hasan; Yagmurcukardes, Nesli; Demic, Serafettin; Icli, Sıddık; Okur, Salih

    2014-01-01

    Graphical abstract: - Highlights: • We report that the performance of OLED consist of aromatic small molecules with double bond carboxylic acid groups on ITO surface. • The OLED devices were tested in terms of electrical and optical characteristics. • The I–V results show that OLEDs with SAM-modified ITO surface have lower turn on voltages than OLED configurations without SAMs. - Abstract: 5-[(3-Methylphenyl)(phenyl)amino]isophthalic acid (5-MePIFA) and 5-(diphenyl)amino]isophthalic acid (5-DPIFA) organic molecules were synthesized to form self-assembled monolayer on indium tin oxide (ITO) anode to enhance hole transport from ITO to organic hole transport layers such as TPD. The modified surface was characterized by scanning tunneling microscopy (STM). The change in the surface potential was measured by Kelvin probe force microscopy (KPFM). Our Kelvin probe force microscopy (KPFM) measurements showed that the surface potentials increased more than 100 mV with reference to bare indium tin-oxide. The results show that the threshold voltage on OLEDs with modified ITO is lowered significantly compared to OLEDs with unmodified ITO. The hole mobility of TPD has been estimated using space–charge-limited current measurements (SCLC)

  12. Electrical properties of SAM-modified ITO surface using aromatic small molecules with double bond carboxylic acid groups for OLED applications

    Energy Technology Data Exchange (ETDEWEB)

    Can, Mustafa [Izmir Katip Celebi University, Faculty of Engineering, Department of Engineering Sciences, Çiğli, Izmir (Turkey); Havare, Ali Kemal [Toros University, Faculty of Engineering, Electric and Electronic Department, Mersin (Turkey); Aydın, Hasan; Yagmurcukardes, Nesli [Izmir Institute of Technology, Material Science and Engineering, Izmir (Turkey); Demic, Serafettin [Izmir Katip Celebi University, Faculty of Engineering, Department of Material Science and Engineering, Çiğli, Izmir (Turkey); Icli, Sıddık [Ege University, Solar Energy Institute, Izmir (Turkey); Okur, Salih, E-mail: salih.okur@ikc.edu.tr [Izmir Katip Celebi University, Faculty of Engineering, Department of Material Science and Engineering, Çiğli, Izmir (Turkey)

    2014-09-30

    Graphical abstract: - Highlights: • We report that the performance of OLED consist of aromatic small molecules with double bond carboxylic acid groups on ITO surface. • The OLED devices were tested in terms of electrical and optical characteristics. • The I–V results show that OLEDs with SAM-modified ITO surface have lower turn on voltages than OLED configurations without SAMs. - Abstract: 5-[(3-Methylphenyl)(phenyl)amino]isophthalic acid (5-MePIFA) and 5-(diphenyl)amino]isophthalic acid (5-DPIFA) organic molecules were synthesized to form self-assembled monolayer on indium tin oxide (ITO) anode to enhance hole transport from ITO to organic hole transport layers such as TPD. The modified surface was characterized by scanning tunneling microscopy (STM). The change in the surface potential was measured by Kelvin probe force microscopy (KPFM). Our Kelvin probe force microscopy (KPFM) measurements showed that the surface potentials increased more than 100 mV with reference to bare indium tin-oxide. The results show that the threshold voltage on OLEDs with modified ITO is lowered significantly compared to OLEDs with unmodified ITO. The hole mobility of TPD has been estimated using space–charge-limited current measurements (SCLC)

  13. Complexation of carboxylate on smectite surfaces.

    Science.gov (United States)

    Liu, Xiandong; Lu, Xiancai; Zhang, Yingchun; Zhang, Chi; Wang, Rucheng

    2017-07-19

    We report a first principles molecular dynamics (FPMD) study of carboxylate complexation on clay surfaces. By taking acetate as a model carboxylate, we investigate its inner-sphere complexes adsorbed on clay edges (including (010) and (110) surfaces) and in interlayer space. Simulations show that acetate forms stable monodentate complexes on edge surfaces and a bidentate complex with Ca 2+ in the interlayer region. The free energy calculations indicate that the complexation on edge surfaces is slightly more stable than in interlayer space. By integrating pK a s and desorption free energies of Al coordinated water calculated previously (X. Liu, X. Lu, E. J. Meijer, R. Wang and H. Zhou, Geochim. Cosmochim. Acta, 2012, 81, 56-68; X. Liu, J. Cheng, M. Sprik, X. Lu and R. Wang, Geochim. Cosmochim. Acta, 2014, 140, 410-417), the pH dependence of acetate complexation has been revealed. It shows that acetate forms inner-sphere complexes on (110) in a very limited mildly acidic pH range while it can complex on (010) in the whole common pH range. The results presented in this study form a physical basis for understanding the geochemical processes involving clay-organics interactions.

  14. Rhodium-catalyzed regioselective olefination directed by a carboxylic group.

    Science.gov (United States)

    Mochida, Satoshi; Hirano, Koji; Satoh, Tetsuya; Miura, Masahiro

    2011-05-06

    The ortho-olefination of benzoic acids can be achieved effectively through rhodium-catalyzed oxidative coupling with alkenes. The carboxylic group is readily removable to allow ortho-olefination/decarboxylation in one pot. α,β-Unsaturated carboxylic acids such as methacrylic acid also undergo the olefination at the β-position. Under the rhodium catalysis, the cine-olefination of heteroarene carboxylic acids such as thiophene-2-carboxylic acid proceeds smoothly accompanied by decarboxylation to selectively produce the corresponding vinylheteroarene derivatives. © 2011 American Chemical Society

  15. Cyclodextrin derivatives with cyanohydrin and carboxylate groups as artificial glycosidases

    DEFF Research Database (Denmark)

    Bols, Mikael; Ortega-Caballero, Fernando

    2006-01-01

    Two cyclodextrin derivatives (1 and 2) were prepared in an attempt to create glycosidase mimics with a general acid catalyst and a nucleophilic carboxylate group. The catalysts 1 and 2 were found to catalyse the hydrolysis of 4-nitrophenyl beta-D-glucopyranoside at pH 8.0, but rapidly underwent...... decomposition with loss of hydrogen cyanide to convert the cyanohydrin to the corresponding aldehyde. The initial rate of the catalysis shows that the cyanohydrin group in these molecules functions as a good catalyst, but that the carboxylate has no positive effect. The decomposition product aldehydes display...

  16. Ovalbumin with Glycated Carboxyl Groups Shows Membrane-Damaging Activity

    Directory of Open Access Journals (Sweden)

    Ching-Chia Tang

    2017-02-01

    Full Text Available The aim of the present study was to investigate whether glycated ovalbumin (OVA showed novel activity at the lipid-water interface. Mannosylated OVA (Man-OVA was prepared by modification of the carboxyl groups with p-aminophenyl α-dextro (d-mannopyranoside. An increase in the number of modified carboxyl groups increased the membrane-damaging activity of Man-OVA on cell membrane-mimicking vesicles, whereas OVA did not induce membrane permeability in the tested phospholipid vesicles. The glycation of carboxyl groups caused a notable change in the gross conformation of OVA. Moreover, owing to their spatial positions, the Trp residues in Man-OVA were more exposed, unlike those in OVA. Fluorescence quenching studies suggested that the Trp residues in Man-OVA were located on the interface binds with the lipid vesicles, and their microenvironment was abundant in positively charged residues. Although OVA and Man-OVA showed a similar binding affinity for lipid vesicles, the lipid-interacting feature of Man-OVA was distinct from that of OVA. Chemical modification studies revealed that Lys and Arg residues, but not Trp residues, played a crucial role in the membrane-damaging activity of Man-OVA. Taken together, our data suggest that glycation of carboxyl groups causes changes in the structural properties and membrane-interacting features of OVA, generating OVA with membrane-perturbing activities at the lipid-water interface.

  17. Determination of carboxyl groups in wood fibers by headspace gas chromatography

    Science.gov (United States)

    X.-S. Chai; Q.X. Hou; J.Y. Zhu; S.-L. Chen; S.F. Wang; L. Lucia

    2003-01-01

    The phase reaction conversion (PRC) headspace gas chromatographic (HSGC) technique was employed to develop a method for the determination of the content of carboxyl groups in wood fibers. Acid treatment of the wood fibers using hydrochloric was applied to convert carboxyl groups to carboxyl acids. Bicarbonate solution is then used to react with carboxyl acids on the...

  18. Synthesis and bioactivities of Phenazine-1-carboxylic acid derivatives based on the modification of PCA carboxyl group.

    Science.gov (United States)

    Xiong, Zhipeng; Niu, Junfan; Liu, Hao; Xu, Zhihong; Li, Junkai; Wu, Qinglai

    2017-05-01

    Phenazine-1-carboxylic acid (PCA) as a natural product widely exists in microbial metabolites of Pseudomonads and Streptomycetes and has been registered for the fungicide against rice sheath blight in China. To find higher fungicidal activities compounds and study the effects on fungicidal activities after changing the carboxyl group of PCA, we synthesized a series of PCA derivatives by modifying the carboxyl group of PCA and their structures were confirmed by 1 H NMR and HRMS. Most compounds exhibited significant fungicidal activities in vitro. In particular, compound 6 exhibited inhibition effect against Rhizoctonia solani with EC 50 values of 4.35mg/L and compound 3b exhibited effect against Fusarium graminearum with EC 50 values of 8.30mg/L, compared to the positive control PCA with its EC 50 values of 7.88mg/L (Rhizoctonia solani) and 127.28mg/L (Fusarium graminearum), respectively. The results indicated that the carboxyl group of PCA could be modified to be amide group, acylhydrazine group, ester group, methyl, hydroxymethyl, chloromethyl and ether group etc. And appropriate modifications on carboxyl group of PCA were useful to extend the fungicidal scope. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Confinement effect of protonation/deprotonation of carboxylic group modified in nanochannel

    International Nuclear Information System (INIS)

    Gao, Hong-Li; Zhang, Hui; Li, Cheng-Yong; Xia, Xing-Hua

    2013-01-01

    Protonation and deprotonation processes are the key step of acid–base reaction and occur in many biological processes. Study on the deprotonation process of molecules and/or functional groups in confined conditions would help us understand the acid–base theory and confinement effect of biomolecules. In this paper, we use a recently established approach to the study of protonation and deprotonation processes of functional groups in porous anodic alumina array nanochannels by measuring the flux of electrochemical active probes (ferricyanide ions) using an Au film electrochemical detector sputtered at the end of nanochannels. The protonation and deprotonation processes of surface functional groups in nanochannels will change the surface charges and in turn modulate the transportation of charged electroactive probes through nanochannels. The titration curve for the deprotonation of carboxylic groups in nanochannel confined conditions is obtained by measuring the current signal of ferricyanide probe flowing through an carboxylic-anchored PAA nanochannels array at different solution pH. Results show that the deprotonation of carboxylic group in nanochannel occurs in one step with a pK 1/2 = 6.2. The present method provides an effective tool to study the deprotonation processes of various functional groups and biomolecules under confined conditions

  20. Microarray of DNA probes on carboxylate functional beads surface

    Institute of Scientific and Technical Information of China (English)

    黄承志; 李原芳; 黄新华; 范美坤

    2000-01-01

    The microarray of DNA probes with 5’ -NH2 and 5’ -Tex/3’ -NH2 modified terminus on 10 um carboxylate functional beads surface in the presence of 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) is characterized in the preseni paper. it was found that the microarray capacity of DNA probes on the beads surface depends on the pH of the aqueous solution, the concentra-tion of DNA probe and the total surface area of the beads. On optimal conditions, the minimum distance of 20 mer single-stranded DNA probe microarrayed on beads surface is about 14 nm, while that of 20 mer double-stranded DNA probes is about 27 nm. If the probe length increases from 20 mer to 35 mer, its microarray density decreases correspondingly. Mechanism study shows that the binding mode of DNA probes on the beads surface is nearly parallel to the beads surface.

  1. Microarray of DNA probes on carboxylate functional beads surface

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The microarray of DNA probes with 5′-NH2 and 5′-Tex/3′-NH2 modified terminus on 10 m m carboxylate functional beads surface in the presence of 1-ethyl-3-(3-dimethylaminopropyl)- carbodiimide (EDC) is characterized in the present paper. It was found that the microarray capacity of DNA probes on the beads surface depends on the pH of the aqueous solution, the concentration of DNA probe and the total surface area of the beads. On optimal conditions, the minimum distance of 20 mer single-stranded DNA probe microarrayed on beads surface is about 14 nm, while that of 20 mer double-stranded DNA probes is about 27 nm. If the probe length increases from 20 mer to 35 mer, its microarray density decreases correspondingly. Mechanism study shows that the binding mode of DNA probes on the beads surface is nearly parallel to the beads surface.

  2. Rational design of carboxyl groups perpendicularly attached to a graphene sheet: a platform for enhanced biosensing applications.

    Science.gov (United States)

    Bonanni, Alessandra; Chua, Chun Kiang; Pumera, Martin

    2014-01-03

    Graphene oxide (GO)-based materials offer great potential for biofunctionalization with applications ranging from biosensing to drug delivery. Such biofunctionalization utilizes specific functional groups, typically a carboxyl moiety, as anchoring points for biomolecule. However, due to the fact that the exact chemical structure of GO is still largely unknown and poorly defined (it was postulated to consist of various oxygen-containing groups, such as epoxy, hydroxyl, carboxyl, carbonyl, and peroxy in varying ratios), it is challenging to fabricate highly biofunctionalized GO surfaces. The predominant anchoring sites (i.e., carboxyl groups) are mainly present as terminal groups on the edges of GO sheets and thus account for only a fraction of the oxygen-containing groups on GO. Herein, we suggest a direct solution to the long-standing problem of limited abundance of carboxyl groups on GO; GO was first reduced to graphene and consequently modified with only carboxyl groups grafted perpendicularly to its surface by a rational synthesis using free-radical addition of isobutyronitrile with subsequent hydrolysis. Such grafted graphene oxide can contain a high amount of carboxyl groups for consequent biofunctionalization, at which the extent of grafting is limited only by the number of carbon atoms in the graphene plane; in contrast, the abundance of carboxyl groups on "classical" GO is limited by the amount of terminal carbon atoms. Such a graphene platform embedded with perpendicularly grafted carboxyl groups was characterized in detail by X-ray photoelectron spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy, and its application was exemplified with single-nucleotide polymorphism detection. It was found that the removal of oxygen functionalities after the chemical reduction enhanced the electron-transfer rate of the graphene. More importantly, the introduction of carboxyl groups promoted a more efficient immobilization of DNA probes on the

  3. Interaction of 1-iodochlordecone, as radioactive tracer, with the carboxylate group on activated carbon

    International Nuclear Information System (INIS)

    Gamboa-Carballo, Juan José; Melchor-Rodríguez, Kenia; Hernández-Valdés, Daniel; Jáuregui-Haza, Ulises Javier

    2016-01-01

    Chlordecone is a synthetic organo chlorinated compound that has been used as pesticide. It has been identified and listed as persistent organic pollutant by the Stockholm Convention. The use of activated carbon filters is one of the most widely popular solutions for water decontamination. The chlordecone labeled with radioactive iodine (1-iodochordecone) is a potential radioactive tracer for studying adsorption, environmental availability and bio-distribution of chlordecone. The selection of the best suited activation carbon for this type of contaminants is mainly an empiric process, increasing the costs of research. A simplified activation carbon model, consisting of a seven ring graphene sheet with a functional group (carboxylate) was used to assess the interaction of chlordecone and 1-iodochlordecone with this surface group under neutral pH conditions over the adsorption process. The Multiple Minima Hypersurface methodology with the semiempirical Hamiltonian PM7 was used. The results indicate that for carboxylate, in neutral conditions, significant associations appear which suggest chemisorption in activated carbon. No significant differences were observed for the interactions of chlordecone and 1 iodochlordecone with carboxylate, making 1-iodochlordecone a good candidate as a radioactive tracer in medical research. (author)

  4. Adsorption of UO2+2 by polyethylene adsorbents with amidoxime, carboxyl, and amidoxime/carboxyl group

    International Nuclear Information System (INIS)

    Choi, Seong-Ho; Nho, Young Chang

    2000-01-01

    The polyethylene (PE) adsorbents were prepared by a radiation-induced grafting of acrylonitrile (AN), acrylic acid (AA), and the mixture of AN/AA onto PE film, and by subsequent amidoximation of cyano groups of poly-AN graft chains. With an increase of AA composition in AN/AA monomer mixture, the water uptake of the grafted polyethylene film increased. In AN/AA mixture, the maximum adsorption of UO 2+ 2 was observed in the adsorbent with a ratio of AN/AA (50/50, mol%) in copolymer. The amidoxime, carboxyl, and amidoxime/carboxyl groups onto PE acted as a chelating site for the selected UO 2+ 2 . The complex structure of polyethylene with three functional groups and UO 2+ 2 was confirmed by Fourier Transform Infrared (FTIR) spectroscopy. (author)

  5. Gold nanostar-enhanced surface plasmon resonance biosensor based on carboxyl-functionalized graphene oxide

    International Nuclear Information System (INIS)

    Wu, Qiong; Sun, Ying; Ma, Pinyi; Zhang, Di; Li, Shuo; Wang, Xinghua; Song, Daqian

    2016-01-01

    A new high-sensitivity surface plasmon resonance (SPR) biosensor based on biofunctional gold nanostars (AuNSs) and carboxyl-functionalized graphene oxide (cGO) sheets was described. Compared with spherical gold nanoparticles (AuNPs), the anisotropic structure of AuNSs, which concentrates the electric charge density on its sharp tips, could enhance the local electromagnetic field and the electronic coupling effect significantly. cGO was obtained by a diazonium reaction of graphene oxide (GO) with 4-aminobenzoic acid. Compared with GO, cGO could immobilize more antibodies due to the abundant carboxylic groups on its surface. Testing results show that there are fairly large improvements in the analytical performance of the SPR biosensor using cGO/AuNSs-antigen conjugate, and the detection limit of the proposed biosensor is 0.0375 μg mL"−"1, which is 32 times lower than that of graphene oxide-based biosensor. - Highlights: • A sensitive and versatile SPR biosensor was constructed for detection of pig IgG. • Biofunctional gold nanostars were used to amplify the response signals. • The strategy employed carboxyl-functionalized graphene oxide as biosensing substrate. • The detection limit of the proposed biosensor is 32 times lower than that of graphene oxide-based biosensor.

  6. Gold nanostar-enhanced surface plasmon resonance biosensor based on carboxyl-functionalized graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Qiong; Sun, Ying; Ma, Pinyi; Zhang, Di; Li, Shuo; Wang, Xinghua; Song, Daqian, E-mail: songdq@jlu.edu.cn

    2016-03-24

    A new high-sensitivity surface plasmon resonance (SPR) biosensor based on biofunctional gold nanostars (AuNSs) and carboxyl-functionalized graphene oxide (cGO) sheets was described. Compared with spherical gold nanoparticles (AuNPs), the anisotropic structure of AuNSs, which concentrates the electric charge density on its sharp tips, could enhance the local electromagnetic field and the electronic coupling effect significantly. cGO was obtained by a diazonium reaction of graphene oxide (GO) with 4-aminobenzoic acid. Compared with GO, cGO could immobilize more antibodies due to the abundant carboxylic groups on its surface. Testing results show that there are fairly large improvements in the analytical performance of the SPR biosensor using cGO/AuNSs-antigen conjugate, and the detection limit of the proposed biosensor is 0.0375 μg mL{sup −1}, which is 32 times lower than that of graphene oxide-based biosensor. - Highlights: • A sensitive and versatile SPR biosensor was constructed for detection of pig IgG. • Biofunctional gold nanostars were used to amplify the response signals. • The strategy employed carboxyl-functionalized graphene oxide as biosensing substrate. • The detection limit of the proposed biosensor is 32 times lower than that of graphene oxide-based biosensor.

  7. Multiple functionalization of multi-walled carbon nanotubes with carboxyl and amino groups

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Zhiyuan [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Yang, Zhanhong, E-mail: zhongnan320@gmail.com [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Key Laboratory of Resource Chemistry of Nonferrous Metals, Ministry of Education, Central South University, Changsha 410083 (China); Hu, Youwang; Li, Jianping [College of Mechanical and Electrical Engineering, Central South University, Changsha 410083 (China); Fan, Xinming [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

    2013-07-01

    In this paper, carboxyl and amino groups have been introduced onto the surface of the multi-walled carbon nanotubes (MWCNTs) by the mixed acid treatment and the diazonium reaction, respectively. The presence of multifunctionality groups on the MWCNTs has been characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric (TGA) analysis, Raman spectra, scanning electron microscopy (SEM) and energy dispersive X-ray spectrum (EDS). The multifunctionalized carbon nanotubes were further utilized to react with acetyl chloride and ethylenediamine (EDA). The formation of the amide bond in the grafting reaction has been confirmed by FT-IR spectroscopy. The result indicates that the further grafting is successful. The multifunctionalized MWCNTs can be a new versatile platform for many interesting applications.

  8. Hydrophobic, ductile, and transparent nanocellulose films with quaternary alkylammonium carboxylates on nanofibril surfaces.

    Science.gov (United States)

    Shimizu, Michiko; Saito, Tsuguyuki; Fukuzumi, Hayaka; Isogai, Akira

    2014-11-10

    Hydrophobic, ductile, and transparent nanocellulose films were prepared by casting and drying aqueous dispersions of 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized cellulose nanofibrils (TOCNs) with quaternary alkylammoniums (QAs) as counterions for the surface carboxylate groups. TOCN films with tetramethylammonium and tetraethylammonium carboxylates showed high optical transparencies, strain-to-failure values (14-22%), and work-of-fracture values (20-27 MJ m(-3)). The ductility of these films was likely caused by the alkyl chains of the QA groups densely covering the TOCN surfaces and being present at the interfaces between the TOCN elements in the films. The water contact angle of the TOCN-QA films increased to ∼100° by introducing tetra(n-butyl)ammonium groups as counterions. Thus, TOCN film properties can be controlled by changing the chemical structure of the counterions from Na to QAs. The hydrophilic TOCN surfaces can be changed to hydrophobic simply and efficiently by the conversion from TOCN-Na to TOCN-QA, when TOCNs are used as nanofillers in hydrophobic polymer matrices.

  9. Separation of Trace Amount Zn (II Using Additional Carbonyl and Carboxyl Groups Functionalized-Nano Graphene

    Directory of Open Access Journals (Sweden)

    A. Moghimi

    2013-01-01

    Full Text Available A novel and selective method for the fast determination of trace amounts of Zn(IIions in water samples has been developed.  The first additional carbonyl and carboxyl functionalized-nano graphene (SPFNano graphene. The presence of additional carbonyl and carboxyl groups located at the edge of the sheets makes GO sheets strongly hydrophilic, allowing them to readily swell and disperse in water. Based on these oxygen functionalities, different model structures of GO were used as absorbent for extraction of Zn (II   ions by solid phase extraction method. The complexes were eluted with HNO3 (2M10% V.V-1 methanol in acetone and determined the analyte by flame atomic absorption spectrometry.  The procedure is based on the selective formation of Zn (II at optimum pH by elution with organic eluents and determination by flame atomic absorption spectrometry. The method is based on complex formation on the surface of the ENVI-18 DISKTM disks modified carbonyl and carboxyl functionalized-nano graphene oxide molecules covalently bonded together followed by stripping of the retained species by minimum amounts of appropriate organic solvents. The elution is efficient and quantitative. The effect of potential interfering ions, pH, SPFNano graphene, amount, stripping solvent, and sample flow rate were also investigated. Under the optimal experimental conditions, the break-through volume was found to about 1000mL providing a preconcentration factor of 500. The maximum capacity of the disks was found to be 456± 3 µg for Zn2+.The limit of detection of the proposed method is 5ng per 1000mL.The method was applied to the extraction and recovery of Zn in different water samples.

  10. Synthesis and HPLC evaluation of carboxylic acid phases on a hydride surface.

    Science.gov (United States)

    Pesek, Joseph J; Matyska, Maria T; Gangakhedkar, Surekha; Siddiq, Rukhsana

    2006-04-01

    Three organic moieties containing carboxylic acid functional groups are attached to a particulate silica surface through silanization/hydrosilation. Two compounds (undecylenic acid and 10-undecynoic acid) have 11 carbon chains and the other is a five-carbon acid (pentenoic acid). Bonding is confirmed through carbon elemental analysis, diffuse reflectance infrared fourier transform spectroscopy, and carbon-13 and silicon-29 CP-MAS NMR spectroscopy. The bonded phases are tested by HPLC using PTH amino acids, nucleic acids, theophylline-related compounds, anilines, benzoic acid compounds, choline, and tobramycin. The latter two compounds are used to investigate the aqueous normal phase properties of the three bonded materials.

  11. Photoacidic and Photobasic Behavior of Transition Metal Compounds with Carboxylic Acid Group(s)

    Energy Technology Data Exchange (ETDEWEB)

    O’Donnell, Ryan M. [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States; Sampaio, Renato N. [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States; Li, Guocan [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States; Johansson, Patrik G. [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States; Ward, Cassandra L. [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States; Meyer, Gerald J. [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States

    2016-03-10

    Excited state proton transfer studies of six Ru polypyridyl compounds with carboxylic acid/carboxylate group(s) revealed that some were photoacids and some were photobases. The compounds [RuII(btfmb)2(LL)]2+, [RuII(dtb)2(LL)]2+, and [RuII(bpy)2(LL)]2+, where bpy is 2,2'-bipyridine, btfmb is 4,4'-(CF3)2-bpy, and dtb is 4,4'-((CH3)3C)2-bpy, and LL is either dcb = 4,4'-(CO2H)2-bpy or mcb = 4-(CO2H),4'-(CO2Et)-2,2'-bpy, were synthesized and characterized. The compounds exhibited intense metal-to-ligand charge-transfer (MLCT) absorption bands in the visible region and room temperature photoluminescence (PL) with long τ > 100 ns excited state lifetimes. The mcb compounds had very similar ground state pKa’s of 2.31 ± 0.07, and their characterization enabled accurate determination of the two pKa values for the commonly utilized dcb ligand, pKa1 = 2.1 ± 0.1 and pKa2 = 3.0 ± 0.2. Compounds with the btfmb ligand were photoacidic, and the other compounds were photobasic. Transient absorption spectra indicated that btfmb compounds displayed a [RuIII(btfmb–)L2]2+* localized excited state and a [RuIII(dcb–)L2]2+* formulation for all the other excited states. Time dependent PL spectral shifts provided the first kinetic data for excited state proton transfer in a transition metal compound. PL titrations, thermochemical cycles, and kinetic analysis (for the mcb compounds) provided self-consistent pKa* values. The ability to make a single ionizable group photobasic or photoacidic through ligand design was unprecedented and was understood based on the orientation of the lowest-lying MLCT excited state dipole relative to the ligand that contained the carboxylic acid group(s).

  12. Effect of carboxyl anchoring groups in asymmetric zinc phthalocyanine with large steric hindrance on the dye-sensitized solar cell performance

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Wenye; Peng, Bosi; Lin, Li; Li, Renjie; Zhang, Jing, E-mail: jzhang03@whu.edu.cn; Peng, Tianyou, E-mail: typeng@whu.edu.cn

    2015-08-01

    Asymmetric zinc phthalocyanines containing tribenzonaphtho-condensed porphyrazine with six bulky diphenylphenoxy and one or two carboxyl groups are used as sensitizers for dye-sensitized solar cells (DSSCs). It is found that Zn-tri-PcNc-4 having two carboxyl groups shows a slight redshift in the Q-band absorption but a significantly decreased absorbance as compared with Zn-tri-PcNc-8 having one carboxyl group, and Zn-tri-PcNc-4 can be more stably and perpendicularly grafted onto the TiO{sub 2} surface than Zn-tri-PcNc-8, which further leads to the differences in the interfacial charge transfer dynamics and dye-loaded amount. Zn-tri-PcNc-4 with two carboxyl groups grafted onto the TiO{sub 2} electrode surface of DSSC results in a photovoltaic conversion efficiency of 3.22%, higher than that (3.01%) of the analog with one carboxyl group (Zn-tri-PcNc-8), which exhibits a lower short-circuit current but much higher open-circuit voltage. The additional carboxyl group in Zn-tri-PcNc-4 leads to the enhanced dye-loaded amount and the molecular orbital energy level shift toward positive direction, causing more efficient electron injection and higher short-circuit current than Zn-tri-PcNc-8; while the two carboxyl groups of Zn-tri-PcNc-4 would cause more protonation of TiO{sub 2} surface, which possibly leads to the downward shift of TiO{sub 2} conduction band edge, and then to the decreased open-circuit voltage. The present results demonstrate the molecular engineering aspect of ZnPc dyes in which the fine tuning of the energy levels and molecular structures is crucial for high conversion efficiency of DSSCs. - Highlights: • ZnPcs with six diphenylphenoxy and one/two carboxyl groups are used as dyes for DSSCs. • Effect of carboxyl group number on the ZnPc-sensitized cell property are scrutinized. • Grafting two carboxyl groups on ZnPc leads to the enhanced photocurrent and efficiency. • ZnPc with one COOH has a higher open-circuit voltage than its analog with two

  13. Carboxylic acid functional group analysis using constant neutral loss scanning-mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Dron, Julien [Laboratoire de Chimie et Environnement, Marseille Universites (case 29), 3 place Victor Hugo, 13331 Marseille Cedex 3 (France)], E-mail: julien.dron@up.univ-mrs.fr; Eyglunent, Gregory; Temime-Roussel, Brice; Marchand, Nicolas; Wortham, Henri [Laboratoire de Chimie et Environnement, Marseille Universites (case 29), 3 place Victor Hugo, 13331 Marseille Cedex 3 (France)

    2007-12-12

    The present study describes the development of a new analytical technique for the functional group determination of the carboxylic moiety using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS/MS) operated in the constant neutral loss scanning (CNLS) mode. Carboxylic groups were first derivatized into their corresponding methyl esters by reacting with BF{sub 3}/methanol mix and the reaction mixture was then directly injected into the APCI chamber. The loss of methanol (m/z = 32 amu) resulting from the fragmentation of the protonated methyl esters was then monitored. Applying this method together with a statistical approach to reference mixtures containing 31 different carboxylic acids at randomly calculated concentrations demonstrated its suitability for quantitative functional group measurements with relative standard deviations below 15% and a detection limit of 0.005 mmol L{sup -1}. Its applicability to environmental matrices was also shown through the determination of carboxylic acid concentrations inside atmospheric aerosol samples. To the best of our knowledge, it is the first time that the tandem mass spectrometry was successfully applied to functional group analysis, offering great perspectives in the characterization of complex mixtures which are prevailing in the field of environmental analysis as well as in the understanding of the chemical processes occurring in these matrices.

  14. Carboxylic acid functional group analysis using constant neutral loss scanning-mass spectrometry

    International Nuclear Information System (INIS)

    Dron, Julien; Eyglunent, Gregory; Temime-Roussel, Brice; Marchand, Nicolas; Wortham, Henri

    2007-01-01

    The present study describes the development of a new analytical technique for the functional group determination of the carboxylic moiety using atmospheric pressure chemical ionization-mass spectrometry (APCI-MS/MS) operated in the constant neutral loss scanning (CNLS) mode. Carboxylic groups were first derivatized into their corresponding methyl esters by reacting with BF 3 /methanol mix and the reaction mixture was then directly injected into the APCI chamber. The loss of methanol (m/z = 32 amu) resulting from the fragmentation of the protonated methyl esters was then monitored. Applying this method together with a statistical approach to reference mixtures containing 31 different carboxylic acids at randomly calculated concentrations demonstrated its suitability for quantitative functional group measurements with relative standard deviations below 15% and a detection limit of 0.005 mmol L -1 . Its applicability to environmental matrices was also shown through the determination of carboxylic acid concentrations inside atmospheric aerosol samples. To the best of our knowledge, it is the first time that the tandem mass spectrometry was successfully applied to functional group analysis, offering great perspectives in the characterization of complex mixtures which are prevailing in the field of environmental analysis as well as in the understanding of the chemical processes occurring in these matrices

  15. Surface properties and aggregate morphology of partially fluorinated carboxylate-type anionic gemini surfactants.

    Science.gov (United States)

    Yoshimura, Tomokazu; Bong, Miri; Matsuoka, Keisuke; Honda, Chikako; Endo, Kazutoyo

    2009-11-01

    Three anionic homologues of a novel partially fluorinated carboxylate-type anionic gemini surfactant, N,N'-di(3-perfluoroalkyl-2-hydroxypropyl)-N,N'-diacetic acid ethylenediamine (2C(n)(F) edda, where n represents the number of carbon atoms in the fluorocarbon chain (4, 6, and 8)) were synthesized. In these present gemini surfactants, the relatively small carboxylic acid moieties form hydrophilic head groups. The surface properties or structures of the aggregates of these surfactants are strongly influenced by the nonflexible fluorocarbons and small head groups; this is because these surfactants have a closely packed molecular structure. The equilibrium surface tension properties of these surfactants were measured at 298.2K for various fluorocarbon chain lengths. The plot of the logarithm of the critical micelle concentration (cmc) against the fluorocarbon chain lengths for 2C(n)(F) edda (n=4, 6, and 8) showed a minimum for n=6. Furthermore, the lowest surface tension of 2C(6)(F) edda at the cmc was 16.4mNm(-1). Such unique behavior has not been observed even in the other fluorinated surfactants. Changes in the shapes and sizes of these surfactant aggregate with concentration were investigated by dynamic light scattering and transmission electron microscopy (TEM). The TEM micrographs showed that in an aqueous alkali solution, 2C(n)(F) edda mainly formed aggregates with stringlike (n=4), cagelike (n=6), and distorted bilayer structures (n=8). The morphological changes in the aggregates were affected by the molecular structure composed of nonflexible fluorocarbon chains and flexible hydrocarbon chains.

  16. Towards modelling the vibrational signatures of functionalized surfaces: carboxylic acids on H-Si(111) surfaces

    Science.gov (United States)

    Giresse Tetsassi Feugmo, Conrard; Champagne, Benoît; Caudano, Yves; Cecchet, Francesca; Chabal, Yves J.; Liégeois, Vincent

    2012-03-01

    In this work, we investigate the adsorption process of two carboxylic acids (stearic and undecylenic) on a H-Si(111) surface via the calculation of structural and energy changes as well as the simulation of their IR and Raman spectra. The two molecules adsorb differently at the surface since the stearic acid simply physisorbs while the undecylenic acid undergoes a chemical reaction with the hydrogen atoms of the surface. This difference is observed in the change of geometry during the adsorption. Indeed, the chemisorption of the undecylenic acid has a bigger impact on the structure than the physisorption of the stearic acid. Consistently, the former is also characterized by a larger value of adsorption energy and a smaller value of the tilting angle with respect to the normal plane. For both the IR and Raman signatures, the spectra of both molecules adsorbed at the surface are in a first approximation the superposition of the spectra of the Si cluster and of the carboxylic acid considered individually. The main deviation from this simple observation is the peak of the stretching Si-H (ν(Si-H)) mode, which is split into two peaks upon adsorption. As expected, the splitting is bigger for the chemisorption than the physisorption. The modes corresponding to atomic displacements close to the adsorption site display a frequency upshift by a dozen wavenumbers. One can also see the disappearance of the peaks associated with the C=C double bond when the undecylenic acid chemisorbs at the surface. The Raman and IR spectra are complementary and one can observe here that the most active Raman modes are generally IR inactive. Two exceptions to this are the two ν(Si-H) modes which are active in both spectroscopies. Finally, we compare our simulated spectra with some experimental measurements and we find an overall good agreement.

  17. Towards modelling the vibrational signatures of functionalized surfaces: carboxylic acids on H-Si(111) surfaces

    International Nuclear Information System (INIS)

    Tetsassi Feugmo, Conrard Giresse; Champagne, Benoît; Liégeois, Vincent; Caudano, Yves; Cecchet, Francesca; Chabal, Yves J

    2012-01-01

    In this work, we investigate the adsorption process of two carboxylic acids (stearic and undecylenic) on a H-Si(111) surface via the calculation of structural and energy changes as well as the simulation of their IR and Raman spectra. The two molecules adsorb differently at the surface since the stearic acid simply physisorbs while the undecylenic acid undergoes a chemical reaction with the hydrogen atoms of the surface. This difference is observed in the change of geometry during the adsorption. Indeed, the chemisorption of the undecylenic acid has a bigger impact on the structure than the physisorption of the stearic acid. Consistently, the former is also characterized by a larger value of adsorption energy and a smaller value of the tilting angle with respect to the normal plane. For both the IR and Raman signatures, the spectra of both molecules adsorbed at the surface are in a first approximation the superposition of the spectra of the Si cluster and of the carboxylic acid considered individually. The main deviation from this simple observation is the peak of the stretching Si-H (ν(Si-H)) mode, which is split into two peaks upon adsorption. As expected, the splitting is bigger for the chemisorption than the physisorption. The modes corresponding to atomic displacements close to the adsorption site display a frequency upshift by a dozen wavenumbers. One can also see the disappearance of the peaks associated with the C=C double bond when the undecylenic acid chemisorbs at the surface. The Raman and IR spectra are complementary and one can observe here that the most active Raman modes are generally IR inactive. Two exceptions to this are the two ν(Si-H) modes which are active in both spectroscopies. Finally, we compare our simulated spectra with some experimental measurements and we find an overall good agreement. (paper)

  18. Measuring the concentration of carboxylic acid groups in torrefied spruce wood.

    Science.gov (United States)

    Khazraie Shoulaifar, Tooran; Demartini, Nikolai; Ivaska, Ari; Fardim, Pedro; Hupa, Mikko

    2012-11-01

    Torrefaction is moderate thermal treatment (∼200-300°C) to improve the energy density, handling and storage properties of biomass fuels. In biomass, carboxylic sites are partially responsible for its hygroscopic. These sites are degraded to varying extents during torrefaction. In this paper, we apply methylene blue sorption and potentiometric titration to measure the concentration of carboxylic acid groups in spruce wood torrefied for 30min at temperatures between 180 and 300°C. The results from both methods were applicable and the values agreed well. A decrease in the equilibrium moisture content at different humidity was also measured for the torrefied wood samples, which is in good agreement with the decrease in carboxylic acid sites. Thus both methods offer a means of directly measuring the decomposition of carboxylic groups in biomass during torrefaction as a valuable parameter in evaluating the extent of torrefaction which provides new information to the chemical changes occurring during torrefaction. Copyright © 2012 Elsevier Ltd. All rights reserved.

  19. Experimental and Theoretical Studies on Corrosion Inhibition of Niobium and Tantalum Surfaces by Carboxylated Graphene Oxide

    Directory of Open Access Journals (Sweden)

    Valbonë Mehmeti

    2018-05-01

    Full Text Available The corrosion of two different metals, niobium and tantalum, in aqueous sulfuric acid solution has been studied in the presence and absence of carboxylated graphene oxide. Potentiodynamic measurements indicate that this nanomaterial inhibits corrosion due to its adsorption on the metal surfaces. The adsorbed layer of carboxylated graphene hinders two electrochemical reactions: the oxidation of the metal and the transport of metal ions from the metal to the solution but also hydrogen evolution reaction by acting as a protective barrier. The adsorption behavior at the molecular level of the carboxylated graphene oxide with respect to Nb, NbO, Ta, and TaO (111 surfaces is also investigated using Molecular Dynamic and Monte Carlo calculations.

  20. The protonation state of small carboxylic acids at the water surface from photoelectron spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Ottosson, N.; Wernersson, Erik; Söderström, J.; Pokapanich, W.; Kaufmann, S.; Svensson, S.; Persson, I.; Öhrwall, G.; Björneholm, O.

    2011-01-01

    Roč. 13, č. 26 (2011), s. 12261-12267 ISSN 1463-9076 Institutional research plan: CEZ:AV0Z40550506 Keywords : water surface * carboxylic acids * photoelectron spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.573, year: 2011

  1. Two types of essential carboxyl groups in Rhodospirillum rubrum proton ATPase

    International Nuclear Information System (INIS)

    Ceccarelli, E.; Vallejos, R.H.

    1983-01-01

    Two different types of essential carboxyl groups were detected in the extrinsic component of the proton ATPase of Rhodospirillum rubrum. Chemical modification of R. rubrum chromatophores or its solubilized ATPase by Woodward's reagent K resulted in inactivation of photophosphorylating and ATPase activities. The apparent order of reaction was nearly 1 with respect to reagent concentration and similar K1 were obtained for the soluble and membrane-bound ATPases suggesting that inactivation was associated with modification of one essential carboxyl group located in the soluble component of the proton ATPase. Inactivation was prevented by adenine nucleotides but not by divalent cations. Dicyclohexylcarbodiimide completely inhibited the solubilized ATPase with a K1 of 5.2 mM and a K2 of 0.81 min-1. Mg2+ afforded nearly complete protection with a Kd of 2.8 mM. Two moles of [14C]dicyclohexylcarbodiimide were incorporated per mole of enzyme for complete inactivation but in the presence of 30 mM MgCl2 only one mole was incorporated and there was no inhibition. The labeling was recovered mostly from the beta subunit. The incorporation of the labeled reagent into the ATPase was not prevented by previous modification with Woodward's reagent K. It is concluded that both reagents modified two different essential carboxyl groups in the soluble ATPase from R. rubrum

  2. Preparation of carboxyl group-modified palladium nanoparticles in an aqueous solution and their conjugation with DNA

    Science.gov (United States)

    Wang, Zhifei; Li, Hongying; Zhen, Shuang; He, Nongyue

    2012-05-01

    The use of nanomaterials in biomolecular labeling and their corresponding detection has been attracting much attention, recently. There are currently very few studies on palladium nanoparticles (Pd NPs) due to their lack of appropriate surface functionalities for conjugation with DNA. In this paper, we thus firstly present an approach to prepare carboxyl group-modified Pd NPs (with an average size of 6 nm) by the use of 11-mercaptoundecanoic acid (MUDA) as a stabilizer in the aqueous solution. The effect of the various reducing reaction conditions on the morphology of the Pd NPs was investigated. The particles were further characterized by TEM, UV-vis, FT-IR and XPS techniques. DNA was finally covalently conjugated to the surface of the Pd NPs through the activation of the carboxyl group, which was confirmed by agarose gel electrophoresis and fluorescence analysis. The resulting Pd NPs-DNA conjugates show high single base pair mismatch discrimination capabilities. This work therefore sets a good foundation for further applications of Pd NPs in bio-analytical research.

  3. Spectroscopic and first principles investigation on 4-[(4-pyridinylmethylene)amino]-benzoic acid bearing pyridyl and carboxyl anchoring groups

    Science.gov (United States)

    Zhang, Lei; Wang, Qiaoyi

    2018-03-01

    We report a combined experimental and computational investigation on the structure and photophysics of 4-[(4-pyridinylmethylene)amino]-benzoic acid, a functional molecule bearing two anchoring groups for attachment onto a TiO2 surface and perovskite surface, for potential solar cell application. This molecule possesses interesting adsorption properties in perovskite solar cell because the pyridyl group serves as the Lewis base and targets Lewis acidic sites in the perovskite surface, while the carboxyl group targets TiO2 surface, improving the coupling between the perovskite surface and the TiO2 surface. The electronic structures of the molecule and its photochemistry are revealed by the UV-vis absorption spectra and the fluorescence spectra under visible light irradiation, which are combined with density functional theory (DFT) and time-dependent density functional theory (TDDFT) analysis. Considering the bi-anchoring groups and the conjugated π system embedded in the molecule, we anticipate it can molecular engineer the TiO2/perovskite interface in perovskite solar cell.

  4. Simple quantification of surface carboxylic acids on chemically oxidized multi-walled carbon nanotubes

    Science.gov (United States)

    Gong, Hyejin; Kim, Seong-Taek; Lee, Jong Doo; Yim, Sanggyu

    2013-02-01

    The surface of multi-walled carbon nanotube (MWCNT) was chemically oxidized using nitric acid and sulfuric-nitric acid mixtures. Thermogravimetric analysis, transmission electron microscopy and infrared spectroscopy revealed that the use of acid mixtures led to higher degree of oxidation. More quantitative identification of surface carboxylic acids was carried out using X-ray photoelectron spectroscopy (XPS) and acid-base titration. However, these techniques are costly and require very long analysis times to promptly respond to the extent of the reaction. We propose a much simpler method using pH measurements and pre-determined pKa value in order to estimate the concentration of carboxylic acids on the oxidized MWCNT surfaces. The results from this technique were consistent with those obtained from XPS and titration, and it is expected that this simple quantification method can provide a cheap and fast way to monitor and control the oxidation reaction of MWCNT.

  5. Reactions and reaction intermediates on iron surfaces--1. Methanol, ethanol, and isopropanol on Fe(100). 2. Hydrocarbons and carboxylic acids

    Energy Technology Data Exchange (ETDEWEB)

    Benziger, J.B.; Madix, R.J.

    1980-09-01

    Temperature-programed desorption and ESCA showed that the alcohols formed alkoxy intermediates on Fe(100) surfaces at room temperature, but that the methoxy and ethoxy species were much more stable than the isopropoxy intermediate. The alkoxy species reacted above 400/sup 0/K by decomposing into carbon monoxide and hydrogen, hydrogenation to alcohol, and scission of C-C and C-O bonds with hydrogenation of the hydrocarbon fragments. Ethylene, acetylene, and cis-2-butene formed stable, unidentified surface species. Methyl chloride formed stable surface methyl groups which decomposed into hydrogen and surface carbide at 475/sup 0/K. Formic and acetic acids yielded stable carboxylate intermediates which decomposed above 490/sup 0/K to hydrogen, carbon monoxide, and carbon dioxide. The studies suggested that the alkoxy surface species may be important intermediates in the Fischer-Tropsch reaction on iron.

  6. Effects of carboxyl and ester anchoring groups on solar conversion efficiencies of TiO2 dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Sepehrifard, A.; Stublla, A.; Haftchenary, S.; Chen, S.; Potvin, P.; Morin, S. [York Univ., Toronto, ON (Canada). Dept. of Chemistry

    2008-07-01

    This paper reported on a study in which 2 new Ruthenium (Ru(2)) dyes bearing different anchoring groups were applied to sensitize TiO2 for dye-sensitized solar cells (DSSCs). The solar conversion efficiencies were measured. Results for 2 of the dyes which carried ester and carboxyl anchoring groups were presented. The extent and nature of the surface binding was studied using electrochemical, UV-visible, fluorescence and FTIR measurements. Solar cell performance was discussed in terms of surface concentration of chemisorbed dyes, electronic properties of the photoanodes and electrochemical properties of adsorbed dyes. The study showed that carboxylic acid groups offer better dye adsorption than ester groups. However, sensitization with warm solutions improved the adsorption of the esterified dye, most likely through transesterification. It was concluded that this may be a useful means of improving solar conversion efficiencies of ester-bearing dyes. 6 refs., 1 tab., 2 figs.

  7. Intramolecular electron transfer through a bridging carboxylate group coordinated to two cobalt(III)-ions

    International Nuclear Information System (INIS)

    Wieghardt, K.

    1978-01-01

    Reduction of the binuclear μ-p-nitrobenzoato -di-μ-hydroxo -bis[triammine cobalt(III)] cation with (CH 3 ) 2 COH radicals yields a radical cation with the p-nitrobenzoato radical being coordinated to two cobalt(III) ions at the carboxylic group. The unprotonated form of this species undergoes intramolecular electron transfer producing Co(II) (k = (3.3 +- 0.3). x 10 3 s -1 ). The role of the carboxylate group in the intramolecular electron transfer process is tentatively assessed in terms of an intramolecular outer-sphere reaction because of lack of overlap of the donor orbitals (π) and the acceptor orbital (sigma). The protonated form of the radical cation (pKsub(a) = 2.5) disproportionates via a bimolecular process without production of Co(II). The effect of two coordinated Co(III) ions as compared to only one on the properties of the nitrobenzoate radical anion are discussed. (orig.) 891 HK 892 GM [de

  8. Carboxyl group modification significantly altered the kinetic properties of purified carboxymethylcellulase from Aspergillus niger.

    Science.gov (United States)

    Siddiqui; Saqib; Rashid; Rajoka

    2000-10-01

    Carboxymethylcellulase (CMCase) from Aspergillus niger NIAB280 was purified by a combination of ammonium sulphate precipitation, ion-exchange, hydrophobic interaction and gel filtration chromatography on FPLC with 9-folds increase in specific activity. Native and subunit molecular weights were found to be 36 kDa each. The purified CMCase was modified by 1-ethyl-3(3-dimethylaminopropyl) carbodiimide (EDC) in the presence of glycinamide for 15 min (GAM15) and glycinamide plus cellobiose for 75 min (GAM75). Similarly, the enzyme was modified by EDC in the presence of ethylenediamine dihydrochloride plus cellobiose for 75 min (EDAM75). The neutralization (GAM15 and GAM75) and reversal (EDAM75) of negative charges of carboxyl groups of CMCase had profound effect on the specificity constant (k(cat)/K(m)), pH optima, pK(a)'s of the active-site residues and thermodynamic parameters of activation. The specificity constants of native, GAM15, GAM75, and EDAM75 were 143, 340, 804, and 48, respectively. The enthalpy of activation (DeltaH(#)) of Carboxymethylcellulose (CMC) hydrolysis of native (50 and 15 kJ mol(-1)) and GAM15 (41 and 16 kJ mol(-1)) were biphasic whereas those of GAM75 (43 kJ mol(-1)) and EDAM75 (41 k J mol(-1)) were monophasic. Similarly, the entropy of activation (DeltaS(#)) of CMC hydrolysis of native (-61 and -173 J mol(-1) K(-1)) and GAM15 (-91 and -171 J mol(-1) K(-1)) were biphasic whereas those of GAM75 (-82 J mol(-1) K(-1)) and EDAM75 (-106 J mol(-1) K(-1)) were monophasic. The pH optima/pK(a)'s of both acidic and basic limbs of charge neutralized CMCases increased compared with those of native enzyme. The CMCase modification in the presence of glycinamide and absence of cellobiose at different pH's periodically activated and inhibited the enzyme activity indicating conformational changes. We believe that the alteration of the surface charges resulted in gross movement of loops that surround the catalytic pocket, thereby inducing changes in the vicinity

  9. Ultrasonic-assisted preparation of graphene oxide carboxylic acid polyvinyl alcohol polymer film and studies of thermal stability and surface resistivity.

    Science.gov (United States)

    Li, Yongshen; Li, Jihui; Li, Yuehai; Li, Yali; Song, Yunan; Niu, Shuai; Li, Ning

    2018-01-01

    In this paper, flake graphite, nitric acid and acetic anhydride are used to prepare graphene oxide carboxylic acid (GO-COOH) via an ultrasonic-assisted method, and GO-COOH and polyvinyl alcohol polymer (PVA) are used to synthesize graphene oxide carboxylic acid polyvinyl alcohol polymer (GO-COOPVA) via the ultrasonic-assisted method, and GO-COOPVA is used to manufacture graphene oxide carboxylic acid polyvinyl alcohol polymer film (GO-COOPVA film) via a solidification method, and the structure and morphology of GO-COOH, GO-COOPVA and GO-COOPVA film are characterized, and the thermal stability and surface resistivity are measured in the case of the different amount of GO-COOH. Based on the characterization and measurement, it has been successively confirmed and attested that carboxyl groups implant on 2D lattice of GO to form GO-COOH, and GO-COOH and PVA have the esterification reaction to produce GO-COOPVA, and GO-COOPVA consists of 2D lattice of GO-COOH and the chain of PVA connected in the form of carboxylic ester, and GO-COOPVA film is composed of GO-COOPVA, and the thermal stability of GO-COOPVA film obviously improves in comparison with PVA film, and the surface resistivity of GO-COOPVA film clearly decreases. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Electrochemical properties of polyolefin nonwoven fabric modified with carboxylic acid group for battery separator

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seong-Ho; Kang, Hae-Jeong; Ryu, Eun-Nyoung; Lee, Kwang-Pill E-mail: kplee@kyungpook.ac.kr

    2001-07-01

    Carboxylic acid group was introduced by radiation-induced grafting of acrylic acid (AAc) onto polyolefine nonwoven fabric (PNF), wherein the PNF comprises at least about 60% of a polyethylene having a melting temperature at {approx}132 deg. C and no more than about 40% of a second polypropylene having a lower melting temperature at {approx}162 deg. C, for a battery separator. The AAc-grafted PNF was characterized by XPS, SEM, DSC, TGA and porosimeter. The wetting speed, electrolyte retention, electrical resistance, and tensile strength were evaluated after grafting of AAc. It was found that the wetting speed, electrolyte retention, thickness, and ion-exchange capacity increased, whereas the electrical resistance decreased with increasing grafting yield. The tensile strength decreased with increasing grafting yield, whereas the elongation decreased with increasing grafting yield. (author)

  11. Electrochemical properties of polyolefine nonwoven fabric modified with carboxylic acid group for battery separator

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seong-Ho; Park, Keung-Shik; Kang, Hae-Jeong; Ryu, Eun-Nyoung; Lee, Pill-Kwang [Department of Chemistry Graduate School, Kyungpook National University, Taegu (Korea)

    2000-07-01

    Carboxylic acid group was introduced by radiation-induced grafting of acrylic acid (AAc) onto polyolefine nonwoven fabric (PNF), wherein the PNF comprises at least about 60% of a polyethylene having a melting temperature at {approx}132degC and no more than about 40% of a second polypropylene having a lower melting temperature at {approx}162degC, for a battery separator. The AAc-grafted PNF was characterized by XPS, SEM, DSC, TGA and porosimeter. The wetting speed, electrolyte retention, electrical resistance, and tensile strength were evaluated after grafting of AAc. It was found that the wetting speed, electrolyte retention, thickness, and ion-exchange capacity increased, whereas the electrical resistance decreased with increasing grafting yield. The tensile strength decreased with increasing grafting yield, whereas the elongation decreased with increasing grafting yield. (author)

  12. Enriched surface acidity for surfactant-free suspensions of carboxylated carbon nanotubes purified by centrifugation

    Directory of Open Access Journals (Sweden)

    Elizabeth I. Braun

    2016-06-01

    Full Text Available It is well known that surfactant-suspended carbon nanotube (CNT samples can be purified by centrifugation to decrease agglomerates and increase individually-dispersed CNTs. However, centrifugation is not always part of protocols to prepare CNT samples used in biomedical applications. Herein, using carboxylated multi-walled CNTs (cMWCNTs suspended in water without a surfactant, we developed a Boehm titrimetric method for the analysis of centrifuged cMWCNT suspensions and used it to show that the surface acidity of oxidized carbon materials in aqueous cMWCNT suspensions was enriched by ∼40% by a single low-speed centrifugation step. This significant difference in surface acidity between un-centrifuged and centrifuged cMWCNT suspensions has not been previously appreciated and is important because the degree of surface acidity is known to affect the interactions of cMWCNTs with biological systems.

  13. Graphs, groups and surfaces

    CERN Document Server

    White, AT

    1985-01-01

    The field of topological graph theory has expanded greatly in the ten years since the first edition of this book appeared. The original nine chapters of this classic work have therefore been revised and updated. Six new chapters have been added, dealing with: voltage graphs, non-orientable imbeddings, block designs associated with graph imbeddings, hypergraph imbeddings, map automorphism groups and change ringing.Thirty-two new problems have been added to this new edition, so that there are now 181 in all; 22 of these have been designated as ``difficult'''' and 9 as ``unsolved''''. Three of the four unsolved problems from the first edition have been solved in the ten years between editions; they are now marked as ``difficult''''.

  14. Phase behavior and micellar properties of carboxylic acid end group modified pluronic surfactants

    NARCIS (Netherlands)

    Custers, J.P.A.; Broeke, van den L.J.P.; Keurentjes, J.T.F.

    2007-01-01

    The micellar behavior of three different carboxylic acid end standing (CAE) surfactants has been characterized using conductometry, differential scanning calorimetry, isothermal titration calorimetry, and dynamic light scattering. The CAE surfactants are modified high molecular weight Pluronic

  15. Protic ammonium carboxylate ionic liquids: insight into structure, dynamics and thermophysical properties by alkyl group functionalization.

    Science.gov (United States)

    Reddy, Th Dhileep N; Mallik, Bhabani S

    2017-04-19

    This study is aimed at characterising the structure, dynamics and thermophysical properties of five alkylammonium carboxylate ionic liquids (ILs) from classical molecular dynamics simulations. The structural features of these ILs were characterised by calculating the site-site radial distribution functions, g(r), spatial distribution functions and structure factors. The structural properties demonstrate that ILs show greater interaction between cations and anions when alkyl chain length increases on the cation or anion. In all ILs, spatial distribution functions show that the anion is close to the acidic hydrogen atoms of the ammonium cation. We determined the role of alkyl group functionalization of the charged entities, cations and anions, in the dynamical behavior and the transport coefficients of this family of ionic liquids. The dynamics of ILs are described by studying the mean square displacement (MSD) of the centres of mass of the ions, diffusion coefficients, ionic conductivities and hydrogen bonds as well as residence dynamics. The diffusion coefficients and ionic conductivity decrease with an increase in the size of the cation or anion. The effect of alkyl chain length on ionic conductivity calculated in this article is consistent with the findings of other experimental studies. Hydrogen bond lifetimes and residence times along with structure factors were also calculated, and are related to alkyl chain length.

  16. The Activity of [60]Fullerene Derivatives Bearing Amine and Carboxylic Solubilizing Groups against Escherichia coli: A Comparative Study

    Directory of Open Access Journals (Sweden)

    Dmitry G. Deryabin

    2014-01-01

    Full Text Available We report a comparative investigation of the antibacterial activity of two water-soluble fullerene derivatives bearing protonated amine (AF and deprotonated carboxylic (CF groups appended to the fullerene cage via organic linkers. The negatively charged fullerene derivative CF showed no tendency to bind to the bacterial cells and, consequently, no significant antibacterial activity. In contrast, the compound AF loaded with cationic groups showed strong and partially irreversible binding to the negatively charged Escherichia coli K12 TG1 cells and to human erythrocytes, also possessing negative zeta potential. Adsorption of AF on the bacterial surface was visualized by atomic force microscopy revealing the formation of specific clusters (AF aggregates surrounding the bacterial cell. Incubation of E. coli K12 TG1 with AF led to a dose-dependent bactericidal effect with LD50 = 79.1 µM. The presence of human erythrocytes in the test medium decreased the AF antibacterial activity. Thus we reveal that the water-soluble cationic fullerene derivative AF possesses promising antibacterial activity, which might be utilized in the development of novel types of chemical disinfectants.

  17. Surface-Supported Robust 2D Lanthanide-Carboxylate Coordination Networks.

    Science.gov (United States)

    Urgel, José I; Cirera, Borja; Wang, Yang; Auwärter, Willi; Otero, Roberto; Gallego, José M; Alcamí, Manuel; Klyatskaya, Svetlana; Ruben, Mario; Martín, Fernando; Miranda, Rodolfo; Ecija, David; Barth, Johannes V

    2015-12-16

    Lanthanide-based metal-organic compounds and architectures are promising systems for sensing, heterogeneous catalysis, photoluminescence, and magnetism. Herein, the fabrication of interfacial 2D lanthanide-carboxylate networks is introduced. This study combines low- and variable-temperature scanning tunneling microscopy (STM) and X-ray photoemission spectroscopy (XPS) experiments, and density functional theory (DFT) calculations addressing their design and electronic properties. The bonding of ditopic linear linkers to Gd centers on a Cu(111) surface gives rise to extended nanoporous grids, comprising mononuclear nodes featuring eightfold lateral coordination. XPS and DFT elucidate the nature of the bond, indicating ionic characteristics, which is also manifest in appreciable thermal stability. This study introduces a new generation of robust low-dimensional metallosupramolecular systems incorporating the functionalities of the f-block elements. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Dancing multiplicity states supported by a carboxylated group in dicopper structures bonded to O2

    KAUST Repository

    Poater, Albert

    2013-01-29

    The present study pretends to assign the correct multiplicity state to dinuclear copper complexes when interacting with free molecular oxygen. Recently, the formation of a bridge butterfly μ-η2: η2-peroxo dicopper core structure stabilized by the direct interaction of the counterion, a carboxylate group that allows the double bridge linking both metal-centre atoms, was characterized by crystallography. This system was assigned as a diradical singlet with Ms = 0. However, after new calculations it has turned out to be triplet (Ms = 1) despite the stabilization for this latter multiplicity state is not high. Here, the factors that contribute to make this structure display a multiplicity different with respect to the previously expected diradical singlet are described. In the present theoretical study, the roles of the αSp ligand constraints and the counterion are unravelled. On the other hand, the relative stability between the butterfly μ-η2: η2-peroxo structure and the isomeric bis(μ-oxo) species is also on discussion. Despite the relative stabilities of all these either structural or electronic isomeric species are supposed to depend on the computational method, which is a difficulty to reach a definite conclusion about the nature of the active species, all DFT methods using either pure or not pure DFT functionals here reach the same conclusion, favoring the triplet as the ground state for the butterfly μ-η2: η2-peroxo dicopper core structure, and the bis(μ-oxo) species when removing the benzoate counterion. © Springer-Verlag Berlin Heidelberg 2013.

  19. Effect of the number of phenyl groups per molecule on the reactivity of hydroxyl or carboxyl group in hydrogen-isotope exchange reaction

    International Nuclear Information System (INIS)

    Okada, Minoru; Imaizumi, Hiroshi; Oguma, Shuichi

    1989-01-01

    Hydrogen-exchange reactions in solid alcohols (or solid carboxylic acids) which contain phenyl group(s) in each molecule have been observed in a gas-solid system or liquid-solid system at 40 ≅ 80deg C. The data thus obtained have been analyzed by using the A''-McKay plot method, and 'the acidities based on kinetic logic' have been obtained for those compounds. From the acidities the following four characteristics have been determined. (1) The acidity increases with increases of temperature. (2) The reactivities of carboxylic acids are larger than those of alcohols at any temperature. (3) The effect of the number of phenyl groups on the reactivity of the functional group in the molecule in question is fairly large. (4) Acidity based on kinetic logic can be applied not only to gas-solid reactions, but also to liquid-solid reactions. (orig.)

  20. “Fifty Shades” of Black and Red or How Carboxyl Groups Fine Tune Eumelanin and Pheomelanin Properties

    Directory of Open Access Journals (Sweden)

    Raffaella Micillo

    2016-05-01

    Full Text Available Recent advances in the chemistry of melanins have begun to disclose a number of important structure-property-function relationships of crucial relevance to the biological role of human pigments, including skin (photo protection and UV-susceptibility. Even slight variations in the monomer composition of black eumelanins and red pheomelanins have been shown to determine significant differences in light absorption, antioxidant, paramagnetic and redox behavior, particle morphology, surface properties, metal chelation and resistance to photo-oxidative wear-and-tear. These variations are primarily governed by the extent of decarboxylation at critical branching points of the eumelanin and pheomelanin pathways, namely the rearrangement of dopachrome to 5,6-dihydroxyindole (DHI and 5,6-dihydroxyindole-2-carboxylic acid (DHICA, and the rearrangement of 5-S-cysteinyldopa o-quinoneimine to 1,4-benzothiazine (BTZ and its 3-carboxylic acid (BTZCA. In eumelanins, the DHICA-to-DHI ratio markedly affects the overall antioxidant and paramagnetic properties of the resulting pigments. In particular, a higher content in DHICA decreases visible light absorption and paramagnetic response relative to DHI-based melanins, but markedly enhances antioxidant properties. In pheomelanins, likewise, BTZCA-related units, prevalently formed in the presence of zinc ions, appear to confer pronounced visible and ultraviolet A (UVA absorption features, accounting for light-dependent reactive oxygen species (ROS production, whereas non-carboxylated benzothiazine intermediates seem to be more effective in inducing ROS production by redox cycling mechanisms in the dark. The possible biological and functional significance of carboxyl retention in the eumelanin and pheomelanin pathways is discussed.

  1. Treatment of sewage from iodo-bromine industrial plants from the second group cations using carboxyl cationnites

    International Nuclear Information System (INIS)

    Kononova, G.N.; Dolbysheva, A.G.; Ksenzenko, V.I.; Ryazantseva, Zh.I.

    1977-01-01

    Effectiveness has been shown of purifying sewage from iodo-bromine plants from the second Group cations on a carboxyl cationite KB-4P. For strongly mineralized waters as industrial waters from iodo-bromine plants, the selectivity decreases in the series: Ca 2+ > Sr 2+ > Mg 2+ . It has been shown that the determining stage is an outside diffusion. SH nitric acid has been used for regeneration of cationite. The second Group cations are washed off with nitric acid simultaneously and at a high rate. Strontium can be separated from the eluate obtained by the halurgical method

  2. Localized conformational interrogation of antibody and antibody-drug conjugates by site-specific carboxyl group footprinting.

    Science.gov (United States)

    Pan, Lucy Yan; Salas-Solano, Oscar; Valliere-Douglass, John F

    Establishing and maintaining conformational integrity of monoclonal antibodies (mAbs) and antibody-drug conjugates (ADCs) during development and manufacturing is critical for ensuring their clinical efficacy. As presented here, we applied site-specific carboxyl group footprinting (CGF) for localized conformational interrogation of mAbs. The approach relies on covalent labeling that introduces glycine ethyl ester tags onto solvent-accessible side chains of protein carboxylates. Peptide mapping is used to monitor the labeling kinetics of carboxyl residues and the labeling kinetics reflects the conformation or solvent-accessibility of side chains. Our results for two case studies are shown here. The first study was aimed at defining the conformational changes of mAbs induced by deglycosylation. We found that two residues in C H 2 domain (D268 and E297) show significantly enhanced side chain accessibility upon deglycosylation. This site-specific result highlighted the advantage of monitoring the labeling kinetics at the amino acid level as opposed to the peptide level, which would result in averaging out of highly localized conformational differences. The second study was designed to assess conformational effects brought on by conjugation of mAbs with drug-linkers. All 59 monitored carboxyl residues displayed similar solvent-accessibility between the ADC and mAb under native conditions, which suggests the ADC and mAb share similar side chain conformation. The findings are well correlated and complementary with results from other assays. This work illustrated that site-specific CGF is capable of pinpointing local conformational changes in mAbs or ADCs that might arise during development and manufacturing. The methodology can be readily implemented within the industry to provide comprehensive conformational assessment of these molecules.

  3. ATR-FTIR Spectroscopic Evidence for Biomolecular Phosphorus and Carboxyl Groups Facilitating Bacterial Adhesion to Iron Oxides

    Science.gov (United States)

    Parikh, Sanjai J.; Mukome, Fungai N.D.; Zhang, Xiaoming

    2014-01-01

    Attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy has been used to probe the binding of bacteria to hematite (α-Fe2O3) and goethite (α-FeOOH). In situ ATR-FTIR experiments with bacteria (Pseudomonas putida, P. aeruginosa, Escherichia coli), mixed amino acids, polypeptide extracts, deoxyribonucleic acid (DNA), and a suite of model compounds were conducted. These compounds represent carboxyl, catecholate, amide, and phosphate groups present in siderophores, amino acids, polysaccharides, phospholipids, and DNA. Due in part to the ubiquitous presence of carboxyl groups in biomolecules, numerous IR peaks corresponding to outer-sphere or unbound (1400 cm−1) and inner-sphere (1310-1320 cm−1) coordinated carboxyl groups are noted following reaction of bacteria and biomolecules with α-Fe2O3 and α-FeOOH. However, the data also reveal that the presence of low-level amounts (i.e., 0.45-0.79%) of biomolecular phosphorous groups result in strong IR bands at ~1043 cm−1, corresponding to inner-sphere Fe-O-P bonds, underscoring the importance of bacteria associated P-containing groups in biomolecule and cell adhesion. Spectral comparisons also reveal slightly greater P-O-Fe contributions for bacteria (Pseudomonad, E. coli) deposited on α-FeOOH, as compared to α-Fe2O3. This data demonstrates that slight differences in bacterial adhesion to Fe oxides can be attributed to bacterial species and Fe-oxide minerals. However, more importantly, the strong binding affinity of phosphate in all bacteria samples to both Fe-oxides results in the formation of inner-sphere Fe-O-P bonds, signifying the critical role of biomolecular P in the initiation of bacterial adhesion. PMID:24859052

  4. Influence of indium-tin oxide surface structure on the ordering and coverage of carboxylic acid and thiol monolayers

    International Nuclear Information System (INIS)

    Cerruti, Marta; Rhodes, Crissy; Losego, Mark; Efremenko, Alina; Maria, Jon-Paul; Fischer, Daniel; Franzen, Stefan; Genzer, Jan

    2007-01-01

    This paper analyses the variability of self-assembled monolayers (SAMs) formation on ITO depending on the substrate surface features. In particular, we report on the formation of carboxylic acid- and thiol-based SAMs on two lots of commercially prepared indium-tin oxide (ITO) thin films. Contact angle measurements, electrochemical experiments, and near-edge x-ray absorption fine structure (NEXAFS) spectroscopy showed that the quality of monolayers formed differed substantially between the two ITO batches. Only one of the two ITO substrates was capable of forming well-organized thiol- and carboxylic acid-based SAMs. In order to rationalize these observations, atomic force microscopy and x-ray diffraction analyses were carried out, and SAMs were prepared on ITO substrates fabricated by sputtering in our laboratories. An attempt was made to influence the film microstructure and surface morphology by varying substrate temperatures during ITO deposition. Good-quality thiol and carboxylic acid SAMs were obtained on one of the ITO substrates prepared in-house. While our characterization could not single out conclusively one specific parameter in ITO surface structure that could be responsible for good SAMs formation, we could point out homogeneous surface morphology as a relevant factor for the quality of the SAMs. Evidence was also found for ITO crystallographic orientation to be a parameter influencing SAMs organization

  5. A new fluorinated urethane dimethacrylate with carboxylic groups for use in dental adhesive compositions

    Energy Technology Data Exchange (ETDEWEB)

    Buruiana, Tinca, E-mail: tbur@icmpp.ro [Polyaddition and Photochemistry Department, Petru Poni Institute of Macromolecular Chemistry, 41 A Grigore Ghica Voda Alley, 700487 Iasi (Romania); Melinte, Violeta [Polyaddition and Photochemistry Department, Petru Poni Institute of Macromolecular Chemistry, 41 A Grigore Ghica Voda Alley, 700487 Iasi (Romania); Aldea, Horia [Gr. T. Popa University of Medicine and Pharmacy, Faculty of Dentistry, 16 University Str., 700115 Iasi (Romania); Pelin, Irina M.; Buruiana, Emil C. [Polyaddition and Photochemistry Department, Petru Poni Institute of Macromolecular Chemistry, 41 A Grigore Ghica Voda Alley, 700487 Iasi (Romania)

    2016-05-01

    A urethane macromer containing hexafluoroisopropylidene, poly(ethylene oxide) and carboxylic moieties (UF-DMA) was synthesized and used in proportions varying between 15 and 35 wt.% (F1–F3) in dental adhesive formulations besides BisGMA, triethylene glycol dimethacrylate and 2-hydroxyethyl methacrylate. The FTIR and {sup 1}H ({sup 13}C) NMR spectra confirmed the chemical structure of the UF-DMA. The experimental adhesives were characterized with regard to the degree of conversion, water sorption/solubility, contact angle, diffusion coefficient, Vickers hardness, and morphology of the crosslinked networks and compared with the specimens containing 10 wt.% hydroxyapatite (HAP) or calcium phosphate (CaP). The conversion degree (after 180 s of irradiation with visible light) ranged from 59.5% (F1) to 74.8% (F3), whereas the water sorption was between 23.15 μg mm{sup −3} (F1) and 40.52 μg mm{sup −3} (F3). Upon the addition of HAP or CaP this parameter attained values of 37.82–49.14 μg mm{sup −3} (F1–F3-HAP) and 34.58–45.56 μg mm{sup −3}, respectively. Also, the formation of resin tags through the infiltration of a dental composition (F3) was visualized by SEM analysis. The results suggest that UF-DMA taken as co-monomer in dental adhesives of acrylic type may provide improved properties in the moist environment of the mouth. - Highlights: • Fluorinated urethane dimethacrylate with carboxylic units (UF-DMA) was proposed as co-monomer in dental adhesives. • UF-DMA exhibits good photoreactivity in mixture with commercial dental monomers. • Water sorption/solubility and diffusion coefficient depend on the amount of UF-DMA. • The infiltration of adhesive mixture into the dentin tubules was evidenced by SEM.

  6. Fluorescence properties of dansyl groups covalently bonded to the surface of oxidatively functionalized low-density polyethylene film

    Science.gov (United States)

    Holmes-Farley, S. R.; Whitesides, G. M.

    1985-12-01

    Brief oxidation of low-density polyethylene film with chromic acid in aqueous sulfuric acid introduced carboxylic acid and ketone and/or aldehyde groups onto the surface of the film. The carboxylic acid moieties can be used to attach more complex functionality to the polymer surface. We are developing this surface-functionalized polyethylene (named polyethylene carboxylic acid, PE-CO2H, to emphasize the functional group that dominates its surface properties) as a substrate with which to study problems in organic surface chemistry--especially wetting, polymer surface reconstruction, and adhesion--using physical-organic techniques. This document describes the preparation, characterization, and fluorescence properties of derivatives of PE-CO2H in which the Dansyl (5-dimethylaminonaphthalene-1-sulfonyl) group has been covalently attached by amide links to the surface carbonyl moieties.

  7. Surface Patterning of Benzene Carboxylic Acids on Graphite: Influence of structure, solvent, and concentration on molecular self-assembly

    Science.gov (United States)

    Florio, Gina; Stiso, Kimberly; Campanelli, Joseph; Dessources, Kimberly; Folkes, Trudi

    2012-02-01

    Scanning tunneling microscopy (STM) was used to investigate the molecular self-assembly of four different benzene carboxylic acid derivatives at the liquid/graphite interface: pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid), trimellitic acid (1,2,4-benzenetricarboxylic acid), trimesic acid (1,3,5-benzenetricarboxylic acid), and 1,3,5-benzenetriacetic acid. A range of two dimensional networks are observed that depend sensitively on the number of carboxylic acids present, the nature of the solvent, and the solution concentration. We will describe our recent efforts to determine (a) the preferential two-dimensional structure(s) for each benzene carboxylic acid at the liquid/graphite interface, (b) the thermodynamic and kinetic factors influencing self-assembly (or lack thereof), (c) the role solvent plays in the assembly, (e) the effect of in situ versus ex situ dilution on surface packing density, and (f) the temporal evolution of the self-assembled monolayer. Results of computational analysis of analog molecules and model monolayer films will also be presented to aid assignment of network structures and to provide a qualitative picture of surface adsorption and network formation.

  8. Carboxylate and amino group coated silver nanoparticles as joining materials for copper-to-copper silver joints.

    Science.gov (United States)

    Oestreicher, A; Röhrich, T; Lerch, M

    2012-12-01

    Organic silver complexes are introduced where silver is linked either with a carboxyl group or with an amino group. Upon heating, nanoparticles are generated if the respective ligands are long enough to act as stabilizing agents in the nanoparticulate regime. With decomposition and volatilization of the organic material, the sintering of silver occurs. The thermal characteristics of the carboxylates silver-n-octanoate, silver-n-decanoate, and AgOOC(CH2OCH2)2CH2OCH3 are compared with silver-n-alkylamines (n = 8, 9, and 12), and their thermal behavior is discussed based on thermogravimetry (TG) measurements. The consecutive stages of a metallization process are addressed based on the properties of AgOOC(CH2OCH2)2CH2OCH3, and the usable effects of the individual phases of this metal organic compound are analyzed by cross-sectional scanning electron microscope (SEM) images of silver joints. Selection criteria are addressed based on the thermal behavior. A mechanism for the joining process is proposed, considering formation and sintering of the nanoparticles. It was found that the bulk material can be used for low-temperature joining processes. Strong adherence to copper as a basic material can be achieved.

  9. Determining the selectivity of divalent metal cations for the carboxyl group of alginate hydrogel beads during competitive sorption.

    Science.gov (United States)

    An, Byungryul; Lee, Healim; Lee, Soonjae; Lee, Sang-Hyup; Choi, Jae-Woo

    2015-11-15

    To investigate the competitive sorption of divalent metal ions such as Ca(2+), Cu(2+), Ni(2+), and Pb(2+) on alginate hydrogel beads, batch and column tests were conducted. The concentration of carboxyl group was found to be limited in the preparation of spherical hydrogel beads. From kinetic test results, 80% of sorption was observed within 4h, and equilibrium was attained in 48 h. According to the comparison of the total uptake and release, divalent metal ions were found to stoichiometrically interact with the carboxyl group in the alginate polymer chain. From the Langmuir equation, the maximum capacities of Pb(2+), Cu(2+), and Ni(2+) were calculated to be 1.1, 0.48, and 0.13 mmol/g, respectively. The separation factor (α) values for αPb/Cu, αPb/Ni, and αCu/Ni were 14.0, 98.9, and 7.1, respectively. The sorption capacity of Pb(2+) was not affected by the solution pH; however, the sorption capacities of Cu(2+) and Ni(2+) decreased with increasing solution pH, caused by competition with hydrogen. According to the result from the fixed column test, Pb(2+) exhibited the highest affinity, followed by Cu(2+) and Ni(2+), which is in exact agreement with those of kinetic and isotherm tests. The sorbent could be regenerated using 4% HCl, and the regenerated sorbent exhibited 90% capacity upto 9 cycles. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. Matrix-Assisted Laser Desorption Ionization Mass Spectrometry of Compounds Containing Carboxyl Groups Using CdTe and CuO Nanoparticles

    OpenAIRE

    Megumi Sakurai; Taro Sato; Jiawei Xu; Soichi Sato; Tatsuya Fujino

    2018-01-01

    Matrix-assisted laser desorption ionization mass spectrometry of compounds containing carboxyl groups was carried out by using semiconductor nanoparticles (CdTe and CuO) as the matrix. Salicylic acid (Sal), glucuronic acid (Glu), ibuprofen (Ibu), and tyrosine (Tyr) were ionized as deprotonated species (carboxylate anions) by using electrons ejected from CdTe after the photoexcitation. When CuO was used as the matrix, the peak intensity of Tyr became high compared with that obtained with CdTe....

  11. Calculating the Ionization Constant of Functional Groups of Carboxyl Ion Exchangers

    Science.gov (United States)

    Meychik, N. R.; Stepanov, S. I.; Nikolaeva, Yu. I.

    2018-02-01

    The potentiometric titration of a weakly basic carboxyl cation exchanger, obtained via alkaline hydrolysis of an acrylonitrile copolymer with divinyl benzene (degree of crosslinking, 12%) in a wide range of variation in a solution of pH (2-12) and NaCl (concentration 0.01, 0.1, 0.5, 1 M), is considered. The maximum ion-exchange capacity of the ion exchanger for Na+ is determined (10.10 ± 0.088 mmol/g of the dry mass) and found to be independent of the solution's ionic strength. It is established that in the investigated range of NaCl concentrations and pH, the acid-base balance is adequately described by Gregor's equation. The parameters of this equation are calculated as a function of the NaCl concentration: p K a = 8.13 ± 0.04, n = 1.50 ± 0.02 for 0.01 M; p K a = 6.56 ± 0.04, n = 2.60 ± 0.07 for 0.1 M; and p K a = 5.66 ± 0.6, n = 2.62 ± 0.06 for 0.5 and 1 M. It is shown that to describe the acid-base balance correctly within the proposed model we must estimate the adequacy of the experimental and calculated values of the ion exchanger's capacity at each pH value according to the calculated parameters of Gregor's equation.

  12. A semi-grand canonical Monte Carlo simulation model for ion binding to ionizable surfaces: proton binding of carboxylated latex particles as a case study.

    Science.gov (United States)

    Madurga, Sergio; Rey-Castro, Carlos; Pastor, Isabel; Vilaseca, Eudald; David, Calin; Garcés, Josep Lluís; Puy, Jaume; Mas, Francesc

    2011-11-14

    In this paper, we present a computer simulation study of the ion binding process at an ionizable surface using a semi-grand canonical Monte Carlo method that models the surface as a discrete distribution of charged and neutral functional groups in equilibrium with explicit ions modelled in the context of the primitive model. The parameters of the simulation model were tuned and checked by comparison with experimental titrations of carboxylated latex particles in the presence of different ionic strengths of monovalent ions. The titration of these particles was analysed by calculating the degree of dissociation of the latex functional groups vs. pH curves at different background salt concentrations. As the charge of the titrated surface changes during the simulation, a procedure to keep the electroneutrality of the system is required. Here, two approaches are used with the choice depending on the ion selected to maintain electroneutrality: counterion or coion procedures. We compare and discuss the difference between the procedures. The simulations also provided a microscopic description of the electrostatic double layer (EDL) structure as a function of pH and ionic strength. The results allow us to quantify the effect of the size of the background salt ions and of the surface functional groups on the degree of dissociation. The non-homogeneous structure of the EDL was revealed by plotting the counterion density profiles around charged and neutral surface functional groups. © 2011 American Institute of Physics

  13. Surface properties of calcium and magnesium oxide nanopowders grafted with unsaturated carboxylic acids studied with inverse gas chromatography.

    Science.gov (United States)

    Maciejewska, Magdalena; Krzywania-Kaliszewska, Alicja; Zaborski, Marian

    2012-09-28

    Inverse gas chromatography (IGC) was applied at infinite dilution to evaluate the surface properties of calcium and magnesium oxide nanoparticles and the effect of surface grafted unsaturated carboxylic acid on the nanopowder donor-acceptor characteristics. The dispersive components (γ(s)(D)) of the free energy of the nanopowders were determined by Gray's method, whereas their tendency to undergo specific interactions was estimated based on the electron donor-acceptor approach presented by Papirer. The calcium and magnesium oxide nanoparticles exhibited high surface energies (79 mJ/m² and 74 mJ/m², respectively). Modification of nanopowders with unsaturated carboxylic acids decreased their specific adsorption energy. The lowest value of γ(s)(D) was determined for nanopowders grafted with undecylenic acid, approximately 55 mJ/m². The specific interactions were characterised by the molar free energy (ΔG(A)(SP)) and molar enthalpy (ΔH(A)(SP)) of adsorption as well as the donor and acceptor interaction parameters (K(A), K(D)). Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Electrochemical impedance and spectroscopy study of the EDC/NHS activation of the carboxyl groups on poly(ε-caprolactone/poly(m-anthranilic acid nanofibers

    Directory of Open Access Journals (Sweden)

    Z. Guler

    2016-02-01

    Full Text Available Electrochemical impedance spectroscopy (EIS and spectroscopy was applied to investigate the surface activation of carboxyl group (–COOH containing nanofibers by the reaction of 1-ethyl-3-(dimethyl-aminopropyl carbodiimide hydrochloride (EDC/N-hydroxyl succinimide (NHS in different concentrations. Poly(!-caprolactone/poly(m-anthranilic acid (PCL/P3ANA nanofibers were fabricated by electrospinning and were activated with 5/0.5, 0.5/5, 5/5 and 50/50 mM of EDC/NHS. The surface activation was investigated by Attenuated Total Reflectance Fourier transform infrared spectroscopy (FTIR-ATR and activation yield was estimated. Albumin was immobilized after surface activation and the amount of covalently immobilized protein was determined by bicinchoninic acid (BCA assay. Morphology and composition of albumin immobilized nanofibers were characterized by Scanning Electron Microscopy/Energy-Dispersive X-ray Spectroscopy (SEM/EDX and Atomic force microscope (AFM. EIS measurements indicated that nanofibers become resistant after albumin immobilization. The obtained data revealed that the highest amount of albumin bound to nanofibers activated with 50/50 mM of EDC/NHS which was found to be the optimum concentration for the activation of PCL/P3ANA nanofibers.

  15. Complexation of vanadium with amidoxime and carboxyl groups. Uncovering the competitive role of vanadium in uranium extraction from seawater

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Cong-Zhi; Wu, Qun-Yan; Lan, Jian-Hui; Shi, Wei-Qun [Chinese Academy of Sciences, Beijing (China). Inst. of High Energy Physics; Chai, Zhi-Fang [Chinese Academy of Sciences, Beijing (China). Inst. of High Energy Physics; Soochow Univ., Suzhou (China). School of Radiological and Interdisciplinary Sciences (RAD-X); Wu, Guo-Zhong [Chinese Academy of Sciences, Shanghai (China). Shanghai Inst. of Applied Physics

    2017-09-01

    At present, amidoxime-based adsorbents are considered to be the most promising materials for extraction of uranium from seawater. However, the high concentrations of transition metals especially vanadium strongly compete with uranium in the sequestration process, which is extremely limited the commercial use of amidoxime-based adsorbents. In this work, the coordination modes, bonding nature, and stabilities of possible vanadium(IV) (VO{sup 2+}) and (V) (VO{sub 2}{sup +}, VO{sup 3+}, V{sup 5+}) complexes with amidoximate (AO{sup -}), carboxyl (Ac{sup -}), glutarimidedioximate (HA{sup -}) and deprotonated glutarimidedioximate (A{sup 2-}) on single and double alkyl chains (R=C{sub 13}H{sub 26}) are systematically explored by quantum chemical calculations. Different from the uranyl (UO{sub 2}{sup 2+}) complexes, the AO{sup -} groups of the vanadium(IV) and (V) complexes prefer to coordinate as monodentate and chelate ligands, while few species with AO{sup -} groups in η{sup 2}-binding mode have been observed in the vanadium complexes. Besides, the vanadium complexes are predicted to have obvious covalent metal-ligand bonds. According to thermodynamic stability analysis, all the vanadium complexes with AO{sup -}, Ac{sup -}, HA{sup -} and A{sup 2-} ligands on double alkyl chains are found to be more stable than corresponding complexes with ligands on a single chain. The synergistic effect of the amidoxime and carboxyl groups can be observed in most of VO{sub 2}{sup +} and VO{sup 3+} complexes with mixed ligands (AO{sup -}/Ac{sup -}). The vanadium(IV) and (V) complexes are more stable than the corresponding uranyl complexes, and the adsorption capability of the amidoxime-based adsorbents toward vanadium(V) ions decrease in the order of VO{sub 2}{sup +}>VO{sup 3+}> V{sup 5+}. The dioxovanadium cation VO{sub 2}{sup +} is predicted to form multinuclear vanadium complex in the sequestration process, possibly resulting in higher stable VO{sub 2}{sup +} complexes. Therefore

  16. First principles investigations on the electronic structure of anchor groups on ZnO nanowires and surfaces

    International Nuclear Information System (INIS)

    Dominguez, A.; Lorke, M.; Rosa, A. L.; Frauenheim, Th.; Schoenhalz, A. L.; Dalpian, G. M.; Rocha, A. R.

    2014-01-01

    We report on density functional theory investigations of the electronic properties of monofunctional ligands adsorbed on ZnO-(1010) surfaces and ZnO nanowires using semi-local and hybrid exchange-correlation functionals. We consider three anchor groups, namely thiol, amino, and carboxyl groups. Our results indicate that neither the carboxyl nor the amino group modify the transport and conductivity properties of ZnO. In contrast, the modification of the ZnO surface and nanostructure with thiol leads to insertion of molecular states in the band gap, thus suggesting that functionalization with this moiety may customize the optical properties of ZnO nanomaterials.

  17. Direct Carboxylation of the Diazo Group ipso-C(sp2)-H bond with Carbon Dioxide: Access to Unsymmetrical Diazomalonates and Derivatives.

    Science.gov (United States)

    Liu, Qianyi; Li, Man; Xiong, Rui; Mo, Fanyang

    2017-12-15

    The direct carboxylation of the ipso-C(sp 2 )-H bond of a diazo compound with carbon dioxide under mild reaction conditions is described. This method is transition-metal-free, uses a weak base, and proceeds at ambient temperature under atmospheric pressure in carbon dioxide. The carboxylation exhibits high reactivity and is amenable to subsequent diversification. A series of unsymmetrical 1,3-diester/keto/amide diazo compounds are obtained with moderate to excellent yields (up to 99%) with good functional group compatibility.

  18. Rapid Screening of Carboxylic Acids from Waste and Surface Waters by ESI-MS/MS Using Barium Ion Chemistry and On-Line Membrane Sampling

    Science.gov (United States)

    Duncan, Kyle D.; Volmer, Dietrich A.; Gill, Chris G.; Krogh, Erik T.

    2016-03-01

    Negative ion tandem mass spectrometric analysis of aliphatic carboxylic acids often yields only non-diagnostic ([M - H]-) ions with limited selective fragmentation. However, carboxylates cationized with Ba2+ have demonstrated efficient dissociation in positive ion mode, providing structurally diagnostic product ions. We report the application of barium adducts followed by collision induced dissociation (CID), to improve selectivity for rapid screening of carboxylic acids in complex aqueous samples. The quantitative MS/MS method presented utilizes common product ions of [M - H + Ba]+ precursor ions. The mechanism of product ion formation is investigated using isotopically labeled standards and a series of structurally related carboxylic acids. The results suggest that hydrogen atoms in the β and γ positions yield common product ions ([BaH]+ and [BaOH]+). Furthermore, the diagnostic product ion at m/z 196 serves as a qualifying ion for carboxylate species. This methodology has been successfully used in conjunction with condensed phase membrane introduction mass spectrometry (CP-MIMS), with barium acetate added directly to the methanol acceptor phase. The combination enables rapid screening of carboxylic acids directly from acidified water samples (wastewater effluent, spiked natural waters) using a capillary hollow fiber PDMS membrane immersion probe. We have applied this technique for the direct analysis of complex naphthenic acid mixtures spiked into natural surface waters using CP-MIMS. Selectivity at the ionization and tandem mass spectrometry level eliminate isobaric interferences from hydroxylated species present within the samples, which have been observed in negative electrospray ionization.

  19. Rapid Screening of Carboxylic Acids from Waste and Surface Waters by ESI-MS/MS Using Barium Ion Chemistry and On-Line Membrane Sampling.

    Science.gov (United States)

    Duncan, Kyle D; Volmer, Dietrich A; Gill, Chris G; Krogh, Erik T

    2016-03-01

    Negative ion tandem mass spectrometric analysis of aliphatic carboxylic acids often yields only non-diagnostic ([M - H](-)) ions with limited selective fragmentation. However, carboxylates cationized with Ba(2+) have demonstrated efficient dissociation in positive ion mode, providing structurally diagnostic product ions. We report the application of barium adducts followed by collision induced dissociation (CID), to improve selectivity for rapid screening of carboxylic acids in complex aqueous samples. The quantitative MS/MS method presented utilizes common product ions of [M - H + Ba](+) precursor ions. The mechanism of product ion formation is investigated using isotopically labeled standards and a series of structurally related carboxylic acids. The results suggest that hydrogen atoms in the β and γ positions yield common product ions ([BaH](+) and [BaOH](+)). Furthermore, the diagnostic product ion at m/z 196 serves as a qualifying ion for carboxylate species. This methodology has been successfully used in conjunction with condensed phase membrane introduction mass spectrometry (CP-MIMS), with barium acetate added directly to the methanol acceptor phase. The combination enables rapid screening of carboxylic acids directly from acidified water samples (wastewater effluent, spiked natural waters) using a capillary hollow fiber PDMS membrane immersion probe. We have applied this technique for the direct analysis of complex naphthenic acid mixtures spiked into natural surface waters using CP-MIMS. Selectivity at the ionization and tandem mass spectrometry level eliminate isobaric interferences from hydroxylated species present within the samples, which have been observed in negative electrospray ionization.

  20. Preparation, Characterization, and In Vitro and Vivo Antitumor Activity of Oridonin-Conjugated Multiwalled Carbon Nanotubes Functionalized with Carboxylic Group

    Directory of Open Access Journals (Sweden)

    Chuanjin Wang

    2016-01-01

    Full Text Available Carbon nanotubes have shown great potential in tumor therapy. Oridonin (ORI is a poorly water-soluble diterpenoid compound (C20H28O6 used in the treatment of esophageal and hepatic carcinoma for decades. For the purpose of enhancing the antitumor potency and reducing cytotoxicity of ORI, multiwalled carbon nanotubes functionalized with carboxylic group (MWCNTs-COOH were used as ORI carrier. ORI was noncovalently encapsulated into (or onto the functionalized carbon nanotubes (MWCNTs-ORI. The obtained MWCNTs-ORI has been characterized. The ORI loading efficiency in MWCNTs-COOH carrier was studied to be about 82.6% (w/w. In vitro cytotoxicity assay on MWCNTs-ORI gave IC50 of 7.29±0.5 μg/mL and ORI-F gave IC50 of 14.5±1.4 μg/mL. The antitumor effect studies in vivo showed that MWCNTs-ORI improved antitumor activity of ORI in comparison with ORI-F. The tumor inhibition ratio for MWCNTs-ORI (1.68×10-2 g·Kg−1·d−1 was 86.4%, higher than that of ORI-F (1.68×10-2 g·Kg−1·d−1 which was 39.2%. This can greatly improve the pharmaceutical efficiency and reduce potential side effects.

  1. Control of Surface Functional Groups on Pertechnetate Sorption on Activated Carbon

    International Nuclear Information System (INIS)

    Y. Wang; H. Gao; R. Yeredla; H. Xu; M. Abrecht; G.D. Stasio

    2006-01-01

    99 Tc is highly soluble and poorly adsorbed by natural materials under oxidizing conditions, thus being of particular concern for radioactive waste disposal. Activated carbon can potentially be used as an adsorbent for removing Tc from aqueous solutions. We have tested six commercial activated carbon materials for their capabilities for sorption of pertechnetate (TcO 4 - ). The tested materials can be grouped into two distinct types: Type I materials have high sorption capabilities with the distribution coefficients (K d ) varying from 9.5 x 10 5 to 3.2 x 10 3 mL/g as the pH changes from 4.5 to 9.5, whereas type II materials have relatively low sorption capabilities with K d remaining more or less constant (1.1 x 10 3 - 1.8 x 10 3 mL/g) over a similar pH range. The difference in sorption behavior between the two types of materials is attributed to the distribution of surface functional groups. The predominant surface groups are identified to be carboxylic and phenolic groups. The carboxylic group can be further divided into three subgroups A, B, and C in the order of increasing acidity. The high sorption capabilities of type I materials are found to be caused by the presence of a large fraction of carboxylic subgroups A and B, while the low sorption capabilities of type II materials are due to the exclusive presence of phenolic and carboxylic subgroup C. Therefore, the performance of activated carbon for removing TcO 4 - can be improved by enhancing the formation of carboxylic subgroups A and B during material processing

  2. The Distant Double Bond Determines the Fate of the Carboxylic Group in the Dissociative Photoionization of Oleic Acid.

    Science.gov (United States)

    Heringa, Maarten F; Slowik, Jay G; Goldmann, Maximilian; Signorell, Ruth; Hemberger, Patrick; Bodi, Andras

    2017-12-15

    The valence threshold photoionization of oleic acid has been studied using synchrotron VUV radiation and imaging photoelectron photoion coincidence (iPEPICO) spectroscopy. An oleic acid aerosol beam was impacted on a copper thermodesorber, heated to 130 °C, to evaporate the particles quantitatively. Upon threshold photoionization, oleic acid produces the intact parent ion first, followed by dehydration at higher energies. Starting at ca. 10 eV, a large number of fragment ions slowly rise suggesting several fragmentation coordinates with quasi-degenerate activation energies. However, water loss is the dominant low-energy dissociation channel, and it is shown to be closely related to the unsaturated carbon chain. In the lowest-barrier process, one of the four allylic hydrogen atoms is transferred to the carboxyl group to form the leaving water molecule and a cyclic ketone fragment ion. A statistical model to analyze the breakdown diagram and measured rate constants yields a 0 K appearance energy of 9.77 eV, which can be compared with the density functional theory result of 9.19 eV. Alternative H-transfer steps yielding a terminal C=O group are ruled out based on energetics and kinetics arguments. Some of the previous photoionization mass spectrometric studies also reported 2 amu and 26 amu loss fragment ions, corresponding to hydrogen and acetylene loss. We could not identify such peaks in the mass spectrum of oleic acid. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Surface modification of commercial seawater reverse osmosis membranes by grafting of hydrophilic monomer blended with carboxylated multiwalled carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Vatanpour, Vahid, E-mail: vahidvatanpour@khu.ac.ir; Zoqi, Naser

    2017-02-28

    Highlights: • A commercial PA RO membrane was modified by grafting of hydrophilic acrylic acid. • COOH-MWCNTs were mixed in grafting layer to increase permeability and antifouling. • However, more increase of CNTs caused in reduction of flux of the membranes. • Effect of acrylic acid amount, contact time and curing time was optimized. - Abstract: In this study, modification of commercial seawater reverse osmosis membranes was carried out with simultaneous use of surface grafting and nanoparticle incorporation. Membrane grafting with a hydrophilic acrylic acid monomer and thermal initiator was used to increase membrane surface hydrophilicity. The used nanomaterial was carboxylated multiwalled carbon nanotubes (MWCNTs), which were dispersed in the grafting solution and deposited on membrane surface to reduce fouling by creating polymer brushes and hydrodynamic resistance. Effectiveness of the grafting process (formation of graft layer on membrane surface) was proved by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses. Increase of membrane surface hydrophilicity was approved with contact angle test. First, the grafting was performed on the membrane surfaces with different monomer concentrations, various contact times and several membrane curing times (three variables for optimization). The modified membranes were tested by a cross-flow setup using saline solution for permeability and rejection tests, and bovine serum albumin (BSA) solution for fouling test. The results showed that the modified membranes with 0.75 M of monomer, 3 min contact time and 80 min curing time in an oven at 50 °C presented the highest flux and lowest rejection decline related to the commercial reverse osmosis membrane. In the next step, the optimum grafting condition was selected and the nanotubes with different weight percentages were dispersed in the acrylic acid monomer solution. The membrane containing 0.25 wt% COOH-MWCNTs showed the

  4. Surface modification of commercial seawater reverse osmosis membranes by grafting of hydrophilic monomer blended with carboxylated multiwalled carbon nanotubes

    International Nuclear Information System (INIS)

    Vatanpour, Vahid; Zoqi, Naser

    2017-01-01

    Highlights: • A commercial PA RO membrane was modified by grafting of hydrophilic acrylic acid. • COOH-MWCNTs were mixed in grafting layer to increase permeability and antifouling. • However, more increase of CNTs caused in reduction of flux of the membranes. • Effect of acrylic acid amount, contact time and curing time was optimized. - Abstract: In this study, modification of commercial seawater reverse osmosis membranes was carried out with simultaneous use of surface grafting and nanoparticle incorporation. Membrane grafting with a hydrophilic acrylic acid monomer and thermal initiator was used to increase membrane surface hydrophilicity. The used nanomaterial was carboxylated multiwalled carbon nanotubes (MWCNTs), which were dispersed in the grafting solution and deposited on membrane surface to reduce fouling by creating polymer brushes and hydrodynamic resistance. Effectiveness of the grafting process (formation of graft layer on membrane surface) was proved by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses. Increase of membrane surface hydrophilicity was approved with contact angle test. First, the grafting was performed on the membrane surfaces with different monomer concentrations, various contact times and several membrane curing times (three variables for optimization). The modified membranes were tested by a cross-flow setup using saline solution for permeability and rejection tests, and bovine serum albumin (BSA) solution for fouling test. The results showed that the modified membranes with 0.75 M of monomer, 3 min contact time and 80 min curing time in an oven at 50 °C presented the highest flux and lowest rejection decline related to the commercial reverse osmosis membrane. In the next step, the optimum grafting condition was selected and the nanotubes with different weight percentages were dispersed in the acrylic acid monomer solution. The membrane containing 0.25 wt% COOH-MWCNTs showed the

  5. Perfluorinated carboxylic and sulphonic acids in surface water media from the regions of Tibetan Plateau: Indirect evidence on photochemical degradation?

    Science.gov (United States)

    Yamazaki, Eriko; Falandysz, Jerzy; Taniyasu, Sachi; Hui, Ge; Jurkiewicz, Gabriela; Yamashita, Nobuyoshi; Yang, Yong-Liang; Lam, Paul K S

    2016-01-01

    Perfluorinated surfactants and repellents are synthetic substances that have found numerous industrial and customer applications. Due to their persistence, at least two groups of these substances-perfluorinated carboxylic acids (PFCAs) and perfluorinated sulfonic acids (PFSAs)-are diffused widely in the environment. It is hypothesized that the Tibetan Plateau, is one of few unique places on the Earth, due to its topography, specifically the vast space and high elevation above sea level, geographic location, climate, high solar radiation, lack of industry, little urbanization and general lack of significant direct sources of pollution. There it is believed possible to gain an insight into atmospheric fate (possible photochemical degradation of higher molecular mass and formation of lower molecular mass PFCAs and PFSAs) of PFASs under un-disturbed environmental conditions. Ultratrace analytical method for PFCAs and PFSAs and use of transportation and field blanks, laboratory blanks and isotopically labelled surrogates for recovery control has allowed the determination of nine perfluorinated carboxylic acids and six perfluorinated sulfonic acids at ultra-trace levels in water based samples from the alpine dimension regions of the Tibetan Plateau, the eastern slope of Minya Konka peak at the eastern edge of the Tibetan Plateau, and also from the city of Chengdu from the lowland of the Sichuan Province in China. The specific compositional pattern of PFCAs and PFSAs and low levels of pollution with those compounds were observed in the central region of the Tibetan Plateau and in the region adjacent to the peaks of Minya Konka in the Eastern Tibetan Plateau. The fingerprint of the compositional pattern of PFCAs and PFSAs in water samples in the central region of the Tibetan Plateau and in the alpine region adjacent to the peaks of Minya Konka in the Eastern Tibetan Plateau may be explained by the result of photochemical degradation with dealkylation of longer chain

  6. A rapid and sensitive method for the simultaneous analysis of aliphatic and polar molecules containing free carboxyl groups in plant extracts by LC-MS/MS

    Directory of Open Access Journals (Sweden)

    Bonaventure Gustavo

    2009-11-01

    Full Text Available Abstract Background Aliphatic molecules containing free carboxyl groups are important intermediates in many metabolic and signalling reactions, however, they accumulate to low levels in tissues and are not efficiently ionized by electrospray ionization (ESI compared to more polar substances. Quantification of aliphatic molecules becomes therefore difficult when small amounts of tissue are available for analysis. Traditional methods for analysis of these molecules require purification or enrichment steps, which are onerous when multiple samples need to be analyzed. In contrast to aliphatic molecules, more polar substances containing free carboxyl groups such as some phytohormones are efficiently ionized by ESI and suitable for analysis by LC-MS/MS. Thus, the development of a method with which aliphatic and polar molecules -which their unmodified forms differ dramatically in their efficiencies of ionization by ESI- can be simultaneously detected with similar sensitivities would substantially simplify the analysis of complex biological matrices. Results A simple, rapid, specific and sensitive method for the simultaneous detection and quantification of free aliphatic molecules (e.g., free fatty acids (FFA and small polar molecules (e.g., jasmonic acid (JA, salicylic acid (SA containing free carboxyl groups by direct derivatization of leaf extracts with Picolinyl reagent followed by LC-MS/MS analysis is presented. The presence of the N atom in the esterified pyridine moiety allowed the efficient ionization of 25 compounds tested irrespective of their chemical structure. The method was validated by comparing the results obtained after analysis of Nicotiana attenuata leaf material with previously described analytical methods. Conclusion The method presented was used to detect 16 compounds in leaf extracts of N. attenuata plants. Importantly, the method can be adapted based on the specific analytes of interest with the only consideration that the

  7. On the nature of oxygen-containing surface groups on carbon nanofibers and their role for platinum deposition—an xps and titration study

    NARCIS (Netherlands)

    Plomp, A.J.; Su, D.S.; de Jong, K.P.; Bitter, J.H.

    2009-01-01

    XPS and acid−base titrations were used to investigate the nature and stability of oxygen-containing surface groups on carbon nanofibers (CNF) and platinum-containing CNF. During heat treatments in inert atmosphere at 973 K all acidic (carboxylic) oxygen surface groups were removed for CNF.

  8. Synthesis and Biological Evaluation of Ru(II) and Pt(II) Complexes Bearing Carboxyl Groups as Potential Anticancer Targeted Drugs.

    Science.gov (United States)

    Martínez, Ma Ángeles; Carranza, M Pilar; Massaguer, Anna; Santos, Lucia; Organero, Juan A; Aliende, Cristina; de Llorens, Rafael; Ng-Choi, Iteng; Feliu, Lidia; Planas, Marta; Rodríguez, Ana M; Manzano, Blanca R; Espino, Gustavo; Jalón, Félix A

    2017-11-20

    The synthesis and characterization of Pt(II) (1 and 2) and Ru(II) arene (3 and 4) or polypyridine (5 and 6) complexes is described. With the aim of having a functional group to form bioconjugates, one uncoordinated carboxyl group has been introduced in all complexes. Some of the complexes were selected for their potential in photodynamic therapy (PDT). The molecular structures of complexes 2 and 5, as well as that of the sodium salt of the 4'-(4-carboxyphenyl)-2,2':6',2″-terpyridine ligand (cptpy), were determined by X-ray diffraction. Different techniques were used to evaluate the binding capacity to model DNA molecules, and MTT cytotoxicity assays were performed against four cell lines. Compounds 3, 4, and 5 showed little tendency to bind to DNA and exhibited poor biological activity. Compound 2 behaves as bonded to DNA probably through a covalent interaction, although its cytotoxicity was very low. Compound 1 and possibly 6, both of which contain a cptpy ligand, were able to intercalate with DNA, but toxicity was not observed for 6. However, compound 1 was active in all cell lines tested. Clonogenic assays and apoptosis induction studies were also performed on the PC-3 line for 1. The photodynamic behavior for complexes 1, 5, and 6 indicated that their nuclease activity was enhanced after irradiation at λ = 447 nm. The cell viability was significantly reduced only in the case of 5. The different behavior in the absence or presence of light makes complex 5 a potential prodrug of interest in PDT. Molecular docking studies followed by molecular dynamics simulations for 1 and the counterpart without the carboxyl group confirmed the experimental data that pointed to an intercalation mechanism. The cytotoxicity of 1 and the potential of 5 in PDT make them good candidates for subsequent conjugation, through the carboxyl group, to "selected peptides" which could facilitate the selective vectorization of the complex toward receptors that are overexpressed in

  9. Radical Initiated Hydrosilylation on Silicon Nanocrystal Surfaces: An Evaluation of Functional Group Tolerance and Mechanistic Study.

    Science.gov (United States)

    Yang, Zhenyu; Gonzalez, Christina M; Purkait, Tapas K; Iqbal, Muhammad; Meldrum, Al; Veinot, Jonathan G C

    2015-09-29

    Hydrosilylation is among the most common methods used for modifying silicon surface chemistry. It provides a wide range of surface functionalities and effective passivation of surface sites. Herein, we report a systematic study of radical initiated hydrosilylation of silicon nanocrystal (SiNC) surfaces using two common radical initiators (i.e., 2,2'-azobis(2-methylpropionitrile) and benzoyl peroxide). Compared to other widely applied hydrosilylation methods (e.g., thermal, photochemical, and catalytic), the radical initiator based approach is particle size independent, requires comparatively low reaction temperatures, and yields monolayer surface passivation after short reaction times. The effects of differing functional groups (i.e., alkene, alkyne, carboxylic acid, and ester) on the radical initiated hydrosilylation are also explored. The results indicate functionalization occurs and results in the formation of monolayer passivated surfaces.

  10. An investigation of the functional groups on the surface of activated carbons

    Directory of Open Access Journals (Sweden)

    MARYTE DERVINYTE

    2004-05-01

    Full Text Available Activated carbons were produced in the laboratory from wood using a 20-run Plackett–Burman experimental design for 19 factors. The obtained batches of activated carbon were analysed by potentiometric titration and FTIR spectroscopy to determine the surface functional groups. The results obtained by potentiometric titration displayed the distribution of individual acidity constants of those groups in the pK range. Considering this parameter, the surface functional groups were divided into carboxyl, lactone and phenol. The linear regression equations reflecting the influence of each operation used for the synthesis on the amount of these functional groups in the obtained activated carbons were generated. The FTIR spectra were used in parallel for the evaluation of the amount and the type of the surface functional groups. Relationships between the two data sets obtained by potentiometric titration and FTIR spectroscopy were evaluated by correlation analysis. It was established that the amount of surface functional groups determined by potentiometric titration positively correlates with the intensity of the peaks of hydrophilic functional groups in the FTIR spectra. At the same time, the negative correlation between potentiometrically determined amount of surface functional groups and the intensity of peaks of hydrophobic functional groups was observed. Most probably, these non-polar formations can take part in the interaction of carbon surface with H+/OH- ions and diminish the strength of existent functional groups.

  11. A soft biomolecule actuator based on a highly functionalized bacterial cellulose nano-fiber network with carboxylic acid groups.

    Science.gov (United States)

    Wang, Fan; Jeon, Jin-Han; Park, Sukho; Kee, Chang-Doo; Kim, Seong-Jun; Oh, Il-Kwon

    2016-01-07

    Upcoming human-related applications such as soft wearable electronics, flexible haptic systems, and active bio-medical devices will require bio-friendly actuating materials. Here, we report a soft biomolecule actuator based on carboxylated bacterial cellulose (CBC), ionic liquid (IL), and poly (3,4-ethylenedioxythiophene)-poly(styrenesulfonate) ( PSS) electrodes. Soft and biocompatible polymer-IL composites were prepared via doping of CBC with ILs. The highly conductive PSS layers were deposited on both sides of the CBC-IL membranes by a dip-coating technique to yield a sandwiched actuator system. Ionic conductivity and ionic exchange capacity of the CBC membrane can be increased up to 22.8 times and 1.5 times compared with pristine bacterial cellulose (BC), respectively, resulting in 8 times large bending deformation than the pure BC actuators with metallic electrodes in an open air environment. The developed CBC-IL actuators show significant progress in the development of biocompatible and soft actuating materials with quick response, low operating voltage and comparatively large bending deformation.

  12. Determination of surface functional groups on mechanochemically activated carbon cloth by Boehm method

    Directory of Open Access Journals (Sweden)

    Đukić Anđelka B.

    2014-01-01

    Full Text Available In order to improve sorption properties of activated carbon cloth that can be used for wastewater purification, mechanochemical activation was performed in both inert and air atmosphere. Boehm method was used to follow the changes in the number and types of surface groups induced by mechanical milling. The number of the base groups of 0,2493 mmol/g is significantly smaller than the total amount of acidic functional groups, 2,5093 mmol/g. Among the acidic groups present on the surface, the most represented are phenolic groups (2.3846 mmol/g , ie . > 95 % , the carboxylic groups are present far less (0.1173 mmol /g, ie. 4.5 %, while the presence of the lactone group on the surface of ACC is negligible (0.0074 mmol/g ie. under 0.3 %. Mechanochemical activation lead to an increase in the number of acidic and basic groups on the surface of the ACC. The milling in inert atmosphere has dominant effect with respect to the changes in the total number of basic functional groups (compared to milling in an air atmosphere: the number of basic groups of the ACC was 0.8153 mmol/g milled under argon, 0.7933 mmol/g in the air; the number of acidic groups is 2.9807 mmol/g for a sample milled under argon and 3.5313 mmol/g for one milled in the air.

  13. 1-Azaniumylcyclobutane-1-carboxylate monohydrate

    Directory of Open Access Journals (Sweden)

    Ray J. Butcher

    2014-02-01

    Full Text Available In the title compound, C5H9NO2·H2O, the amino acid is in the usual zwitterionic form involving the α-carboxylate group. The cyclobutane backbone of the amino acid is disordered over two conformations, with occupancies of 0.882 (7 and 0.118 (7. In the crystal, N—H...O and O—H...O hydrogen bonds link the zwitterions [with the water molecule involved as both acceptor (with the NH3+ and donor (through a single carboxylate O from two different aminocyclobutane carboxylate moities], resulting in a two-dimensional layered structure lying parallel to (100.

  14. Surface modification influencing adsorption of red wine constituents: The role of functional groups

    Science.gov (United States)

    Mierczynska-Vasilev, Agnieszka; Smith, Paul A.

    2016-11-01

    The adsorption of wine constituents at solid surfaces is important in applications such as filtration and membrane fouling, binding to tanks and fittings and interactions with processing aids such as bentonite. The interaction of wine constituents with surfaces is mediated through adsorbed wine components, where the type of constituents, amount, orientation, and conformation are of consequence for the surface response. This study examines the effect of surface chemical functionalities on the adsorption of red wine constituents. Plasma-polymerized films rich in amine, carboxyl, hydroxyl, formyl and methyl functional groups were generated on solid substrates whereas, glycidyltrimethylammonium chloride was covalently attached to allylamine plasma-polymer modified surface and poly(sodium styrenesulfonate) was electrostatically adsorbed to an amine plasma-polymerized surface. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy. The ability of different substrates to adsorb red wine constituents was evaluated by quartz crystal microbalance and atomic force microscopy. The results showed that substrates modified with -SO3H and -COOH groups can adsorb more of the wine nitrogen-containing compounds whereas -NH2 and -NR3 groups encourage carbon-containing compounds adsorption. Red wine constituents after filtration were adsorbed in higher extend on -NR3 and -CHO surfaces. The -OH modified surfaces had the lowest ability to absorb wine components.

  15. Acidic surface functional groups and mineral elements in Lakra coal (Sindh, Pakistan)

    International Nuclear Information System (INIS)

    Saeed, K.; Ishaq, M.; Ahjmad, I.; Shakirullah, M.; Haider, S.

    2010-01-01

    Surface acidity of virgin coal (Lakra Sindh, Pakistan) and variously extracted/leached coal samples with HNO/sub 3/ NaOH, and KMnO/sub 4/, were investigated by aqueous potentiometric titration employing KOH as a titrant. The titration curve of virgin coal showed that its surface might contain carboxylic, carbonyl, phenolic and other weak acidic functional groups such as enols and C-H bond. The titration curves of leached coal samples showed inflections at pH 4-11, being not similar the inflections of carboxylic groups. This inflection might be given by functional groups like CO/sub 2/, phenolic, enols and C-H. Mineral matter such as Fe, K, Zn, Mn and Ni were determined in the ash of coal by atomic absorption spectrophotometer and was found that Fe (3104 micro g/g) in the highest and Ni (36.05 micro g/g) in the lowest quantity is present in virgin coal sample. (author)

  16. 1-(3-aminopropyl)-3-butylimidazolium bromide for carboxyl group derivatization: potential applications in high sensitivity peptide identification by mass spectrometry.

    Science.gov (United States)

    Qiao, Xiaoqiang; Zhou, Yuan; Hou, Chunyan; Zhang, Xiaodan; Yang, Kaiguang; Zhang, Lihua; Zhang, Yukui

    2013-03-01

    The cationic reagent 1-(3-aminopropyl)-3-butylimidazolium bromide (BAPI) was exploited for the derivatization of carboxyl groups on peptides. Nearly 100% derivatization efficiency was achieved with the synthetic peptide RVYVHPI (RI-7). Furthermore, the peptide derivative was stable in a 0.1% TFA/water solution or a 0.1% (v/v) TFA/acetonitrile/water solution for at least one week. The effect of BAPI derivatization on the ionization of the peptide RI-7 was further investigated, and the detection sensitivity was improved >42-fold via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS), thus outperforming the commercial piperazine derivatization approach. Moreover, the charge states of the peptide were largely increased via BAPI derivatization by electrospray ionization (ESI) MS. The results indicate the potential merits of BAPI derivatization for high sensitivity peptide analysis by MS.

  17. Cellulose bearing Schiff base and carboxylic acid chelating groups: a low cost and green adsorbent for heavy metal ion removal from aqueous solution.

    Science.gov (United States)

    Saravanan, R; Ravikumar, L

    2016-10-01

    Chemically modified cellulose bearing metal binding sites like Schiff base and carboxylic acid groups was synthesized and characterized through Fourier transform infrared and solid state 13 C-nuclear magnetic resonance (NMR) analysis. The chemically modified cellulose (Cell-PA) adsorbent was examined for its metal ion uptake ability for Cu(II) and Pb(II) ions from aqueous solution. Kinetic and isotherm studies were carried out under optimum conditions. Pseudo-second-order kinetics and Langmuir isotherm fit well with the experimental data. Thermodynamic studies were also performed along with adsorption regeneration performance studies. The adsorbent (Cell-PA) shows high potential for the removal of Cu(II) and Pb(II) metal ions, and it shows antibacterial activity towards selected microorganisms.

  18. The XPS study of physical and chemical forms of neptunium group on the surface of minerals

    Directory of Open Access Journals (Sweden)

    Teterin Anton Yu.

    2010-01-01

    Full Text Available The sorption behavior and the physical and chemical forms of neptunium on the surface of minerals of the two chlorate samples, biotite and kaolin, with different contents of Fe(II was studied. The liquid-liquid extraction and the X-ray photoelectron spectroscopy were employed to identify the valence forms of neptunium. On the basis of the obtained data the quantitative elemental composition of the surface of the studied minerals, as well as the ionic composition of the formed neptunium complexes was determined. It was shown that the Np(IV and Np(VI containing compounds did not form, while the complexes Np(VO+ -hydroxyl did form on the surface. The oxygen ions bonded with iron and oxygen belonging to water and/or of carboxyl were suggested to be present in the equatorial plane of the neptunyl group NpO+.

  19. Surface modification influencing adsorption of red wine constituents: The role of functional groups

    Energy Technology Data Exchange (ETDEWEB)

    Mierczynska-Vasilev, Agnieszka, E-mail: agnieszka.mierczynska-vasilev@awri.com.au; Smith, Paul A., E-mail: paul.smith@awri.com.au

    2016-11-15

    Highlights: • Chemical surface composition affects behaviour of wine adsorption. • SO{sub 3}H and COOH groups adsorb more of the wine nitrogen-containing compounds. • NH{sub 2} and NR{sub 3} groups encourage carbon-containing compounds adsorption. • Red wine constituents after filtration adsorbed more on NR{sub 3} and CHO surfaces. - Abstract: The adsorption of wine constituents at solid surfaces is important in applications such as filtration and membrane fouling, binding to tanks and fittings and interactions with processing aids such as bentonite. The interaction of wine constituents with surfaces is mediated through adsorbed wine components, where the type of constituents, amount, orientation, and conformation are of consequence for the surface response. This study examines the effect of surface chemical functionalities on the adsorption of red wine constituents. Plasma-polymerized films rich in amine, carboxyl, hydroxyl, formyl and methyl functional groups were generated on solid substrates whereas, glycidyltrimethylammonium chloride was covalently attached to allylamine plasma-polymer modified surface and poly(sodium styrenesulfonate) was electrostatically adsorbed to an amine plasma-polymerized surface. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy. The ability of different substrates to adsorb red wine constituents was evaluated by quartz crystal microbalance and atomic force microscopy. The results showed that substrates modified with −SO{sub 3}H and –COOH groups can adsorb more of the wine nitrogen-containing compounds whereas −NH{sub 2} and −NR{sub 3} groups encourage carbon-containing compounds adsorption. Red wine constituents after filtration were adsorbed in higher extend on −NR{sub 3} and –CHO surfaces. The –OH modified surfaces had the lowest ability to absorb wine components.

  20. Surface modification influencing adsorption of red wine constituents: The role of functional groups

    International Nuclear Information System (INIS)

    Mierczynska-Vasilev, Agnieszka; Smith, Paul A.

    2016-01-01

    Highlights: • Chemical surface composition affects behaviour of wine adsorption. • SO_3H and COOH groups adsorb more of the wine nitrogen-containing compounds. • NH_2 and NR_3 groups encourage carbon-containing compounds adsorption. • Red wine constituents after filtration adsorbed more on NR_3 and CHO surfaces. - Abstract: The adsorption of wine constituents at solid surfaces is important in applications such as filtration and membrane fouling, binding to tanks and fittings and interactions with processing aids such as bentonite. The interaction of wine constituents with surfaces is mediated through adsorbed wine components, where the type of constituents, amount, orientation, and conformation are of consequence for the surface response. This study examines the effect of surface chemical functionalities on the adsorption of red wine constituents. Plasma-polymerized films rich in amine, carboxyl, hydroxyl, formyl and methyl functional groups were generated on solid substrates whereas, glycidyltrimethylammonium chloride was covalently attached to allylamine plasma-polymer modified surface and poly(sodium styrenesulfonate) was electrostatically adsorbed to an amine plasma-polymerized surface. The surface chemical functionalities were characterized by X-ray photoelectron spectroscopy. The ability of different substrates to adsorb red wine constituents was evaluated by quartz crystal microbalance and atomic force microscopy. The results showed that substrates modified with −SO_3H and –COOH groups can adsorb more of the wine nitrogen-containing compounds whereas −NH_2 and −NR_3 groups encourage carbon-containing compounds adsorption. Red wine constituents after filtration were adsorbed in higher extend on −NR_3 and –CHO surfaces. The –OH modified surfaces had the lowest ability to absorb wine components.

  1. High-performance supercapacitors of carboxylate-modified hollow carbon nanospheres coated on flexible carbon fibre paper: Effects of oxygen-containing group contents, electrolytes and operating temperature

    International Nuclear Information System (INIS)

    Phattharasupakun, Nutthaphon; Wutthiprom, Juthaporn; Suktha, Phansiri; Iamprasertkun, Pawin; Chanlek, Narong; Shepherd, Celine; Hadzifejzovic, Emina; Moloney, Mark G.; Foord, John S.; Sawangphruk, Montree

    2017-01-01

    Although functionalized carbon-based materials have been widely used as the supercapacitor electrodes, the optimum contents of the functional groups, the charge storage mechanisms, and the effects of electrolytes and operating temperature have not yet been clearly investigated. In this work, carboxylate-modified hollow carbon nanospheres (c-HCN) with different functional group contents synthesized by an oxidation process of carbon nanospheres with nitric acid were coated on flexible carbon fibre paper and used as the supercapacitor electrodes. An as-fabricated supercapacitor of the c-HCN with a finely tuned 6.2 atomic % of oxygen of the oxygen-containing groups in an ionic liquid electrolyte exhibits a specific capacitance of 390 F g"−"1, a specific energy of 115 Wh kg"−"1, and a maximum specific power of 13548 W kg"−"1 at 70 °C. The charge storage mechanism investigated is based on the chemical adsorption of the ionic liquid electrolyte on the c-HCN electrode. This process is highly reversible leading to high capacity retention. The supercapacitor in this work may be practically used in many high energy and power applications.

  2. The synthesis of CdSe quantum dots with carboxyl group and study on their optical characteristics

    International Nuclear Information System (INIS)

    Ye, Chen; Park, Sangjoon; Kim, Jongsung

    2009-01-01

    Quantum dots are nanocrystal semiconductors which attract lots of research interests due to their peculiar optical properties. CdSe/ZnS quantum dots have been synthesized via pyrolysis of organometallic reagents. The color of the quantum dot changes from yellow-green to red as their size increases with reaction time. Photoluminescence quantum efficiency of CdSe quantum dots have been enhanced by passivating the surface of CdSe quantum dots with ZnS layers. Quantum dots are nanocrystal semiconductors which attract lots of research interests due to their peculiar optical properties. CdSe/ZnS quantum dots have been synthesized via pyrolysis of organometallic reagents. The color of the quantum dot changes from yellow-green to red as their size increases with reaction time. Photoluminescence quantum efficiency of CdSe quantum dots have been enhanced by passivating the surface of CdSe quantum dots with ZnS layers. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Nonlinear dynamics in the perceptual grouping of connected surfaces.

    Science.gov (United States)

    Hock, Howard S; Schöner, Gregor

    2016-09-01

    Evidence obtained using the dynamic grouping method has shown that the grouping of an object's connected surfaces has properties characteristic of a nonlinear dynamical system. When a surface's luminance changes, one of its boundaries is perceived moving across the surface. The direction of this dynamic grouping (DG) motion indicates which of two flanking surfaces has been grouped with the changing surface. A quantitative measure of overall grouping strength (affinity) for adjacent surfaces is provided by the frequency of DG motion perception in directions promoted by the grouping variables. It was found that: (1) variables affecting surface grouping for three-surface objects evolve over time, settling at stable levels within a single fixation, (2) how often DG motion is perceived when a surface's luminance is perturbed (changed) depends on the pre-perturbation affinity state of the surface grouping, (3) grouping variables promoting the same surface grouping combine cooperatively and nonlinearly (super-additively) in determining the surface grouping's affinity, (4) different DG motion directions during different trials indicate that surface grouping can be bistable, which implies that inhibitory interactions have stabilized one of two alternative surface groupings, and (5) when alternative surface groupings have identical affinity, stochastic fluctuations can break the symmetry and inhibitory interactions can then stabilize one of the surface groupings, providing affinity levels are not too high (which results in bidirectional DG motion). A surface-grouping network is proposed within which boundaries vary in salience. Low salience or suppressed boundaries instantiate surface grouping, and DG motion results from changes in boundary salience. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Catalytic ozonation not relying on hydroxyl radical oxidation: A selective and competitive reaction process related to metal-carboxylate complexes

    KAUST Repository

    Zhang, Tao

    2014-01-01

    Catalytic ozonation following non-hydroxyl radical pathway is an important technique not only to degrade refractory carboxylic-containing organic compounds/matter but also to avoid catalyst deactivation caused by metal-carboxylate complexation. It is unknown whether this process is effective for all carboxylates or selective to special molecule structures. In this work, the selectivity was confirmed using O3/(CuO/CeO2) and six distinct ozone-resistant probe carboxylates (i.e., acetate, citrate, malonate, oxalate, pyruvate and succinate). Among these probe compounds, pyruvate, oxalate, and citrate were readily degraded following the rate order of oxalate>citrate>pyruvate, while the degradation of acetate, malonate, and succinate was not promoted. The selectivity was independent on carboxylate group number of the probe compounds and solution pH. Competitive degradation was observed for carboxylate mixtures following the preference order of citrate, oxalate, and finally pyruvate. The competitive degradation was ascribed to competitive adsorption on the catalyst surface. It was revealed that the catalytically degradable compounds formed bidentate chelating or bridging complexes with surface copper sites of the catalyst, i.e., the active sites. The catalytically undegradable carboxylates formed monodentate complexes with surface copper sites or just electrostatically adsorbed on the catalyst surface. The selectivity, relying on the structure of surface metal-carboxylate complex, should be considered in the design of catalytic ozonation process. © 2013 Elsevier B.V.

  5. Mechanism of in situ surface polymerization of gallic acid in an environmental-inspired preparation of carboxylated core-shell magnetite nanoparticles.

    Science.gov (United States)

    Tóth, Ildikó Y; Szekeres, Márta; Turcu, Rodica; Sáringer, Szilárd; Illés, Erzsébet; Nesztor, Dániel; Tombácz, Etelka

    2014-12-30

    Magnetite nanoparticles (MNPs) with biocompatible coatings are good candidates for MRI (magnetic resonance imaging) contrasting, magnetic hyperthermia treatments, and drug delivery systems. The spontaneous surface induced polymerization of dissolved organic matter on environmental mineral particles inspired us to prepare carboxylated core-shell MNPs by using a ubiquitous polyphenolic precursor. Through the adsorption and in situ surface polymerization of gallic acid (GA), a polygallate (PGA) coating is formed on the nanoparticles (PGA@MNP) with possible antioxidant capacity. The present work explores the mechanism of polymerization with the help of potentiometric acid-base titration, dynamic light scattering (for particle size and zeta potential determination), UV-vis (UV-visible light spectroscopy), FTIR-ATR (Fourier-transformed infrared spectroscopy by attenuated total reflection), and XPS (X-ray photoelectron spectroscopy) techniques. We observed the formation of ester and ether linkages between gallate monomers both in solution and in the adsorbed state. Higher polymers were formed in the course of several weeks both on the surface of nanoparticles and in the dispersion medium. The ratio of the absorbances of PGA supernatants at 400 and 600 nm (i.e., the E4/E6 ratio commonly used to characterize the degree of polymerization of humic materials) was determined to be 4.3, similar to that of humic acids. Combined XPS, dynamic light scattering, and FTIR-ATR results revealed that, prior to polymerization, the GA monomers became oxidized to poly(carboxylic acid)s due to ring opening while Fe(3+) ions reduced to Fe(2+). Our published results on the colloidal and chemical stability of PGA@MNPs are referenced thoroughly in the present work. Detailed studies on biocompatibility, antioxidant property, and biomedical applicability of the particles will be published.

  6. Synthesis and characterization of carboxylic acid functionalized silicon nanoparticles

    Science.gov (United States)

    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

  7. Synthesis and Characterization of PEDOT Derivative with Carboxyl Group and Its Chemo/Bio Sensing Application as Nanocomposite, Immobilized Biological and Enhanced Optical Materials

    International Nuclear Information System (INIS)

    Zhang, Long; Wen, Yangping; Yao, Yuanyuan; Xu, Jingkun; Duan, Xuemin; Zhang, Ge

    2014-01-01

    indicate that chemo/bio-sensors based on PC4 possess excellent chemo/bio sensing performance and enhanced optical response, and its carboxylic group can realize the immobilization of biologically active species, self-assembly of inorganic nanomaterials

  8. Effects of chemical functional groups on elemental mercury adsorption on carbonaceous surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Liu Jing, E-mail: liujing27@mail.hust.edu.cn [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074 (China); Cheney, Marcos A. [Department of Natural Sciences, University of Maryland Eastern Shore, Princess Anne, MD 21853 (United States); Wu Fan; Li Meng [State Key Laboratory of Coal Combustion, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2011-02-15

    A systematic theoretical study using density functional theory is performed to provide molecular-level understanding of the effects of chemical functional groups on mercury adsorption on carbonaceous surfaces. The zigzag and armchair edges were used in modeling the carbonaceous surfaces to simulate different adsorption sites. The edge atoms on the upper side of the models are unsaturated to simulate active sites. All calculations (optimizations, energies, and frequencies) were made at B3PW91 density functional theory level, using RCEP60VDZ basis set for mercury and 6-31G(d) pople basis set for other atoms. The results indicate that the embedding of halogen atom can increase the activity of its neighboring site which in turn increases the adsorption capacity of the carbonaceous surface for Hg{sup 0}. The adsorption belongs to chemisorptions, which is in good agreement with the experimental results. For the effects of oxygen functional groups, lactone, carbonyl and semiquinone favor Hg{sup 0} adsorption because they increase the neighboring site's activity for mercury adsorption. On the contrary, phenol and carboxyl functional groups show a physisorption of Hg{sup 0}, and reduce Hg capture. This result can explain the seemingly conflicting experimental results reported in the literature concerning the influence of oxygen functional groups on mercury adsorption on carbonaceous surface.

  9. Effects of alkyl chain length and solvents on thermodynamic dissociation constants of the ionic liquids with one carboxyl group in the alkyl chain of imidazolium cations.

    Science.gov (United States)

    Chen, Yuehua; Wang, Huiyong; Wang, Jianji

    2014-05-01

    Thermodynamic dissociation constants of the Brønsted acidic ionic liquids (ILs) are important for their catalytic and separation applications. In this work, a series of imidazolium bromides with one carboxylic acid substitute group in their alkyl chain ([{(CH2)nCOOH}mim]Br, n = 1,3,5,7) have been synthesized, and their dissociation constants (pKa) at different ionic strengths have been determined in aqueous and aqueous organic solvents at 0.1 mole fraction (x) of ethanol, glycol, iso-propanol, and dimethyl sulfoxide by potentiometric titrations at 298.2 K. The standard thermodynamic dissociation constants (pKa(T)) of the ILs in these solvents were calculated from the extended Debye-Hückel equation. It was found that the pKa values increased with the increase of ionic strength of the media and of the addition of organic solvent in water. The pKa(T) values also increased with the increase of the alkyl chain length of cations of the ILs. In addition, the effect of solvent nature on pKa(T) values is interpreted from solvation of the dissociation components and their Gibbs energy of transfer from water to aqueous organic solutions.

  10. Liquid chromatographic-tandem mass spectrometric method for the simultaneous determination of alkylphenols polyethoxylates, alkylphenoxy carboxylates and alkylphenols in wastewater and surface-water.

    Science.gov (United States)

    Ciofi, L; Ancillotti, C; Chiuminatto, U; Fibbi, D; Checchini, L; Orlandini, S; Del Bubba, M

    2014-10-03

    Four different pellicular stationary phases (i.e. octadecylsilane, octasilane, Phenyl-Hexyl and pentafluorophenyl) were investigated for the chromatographic resolution of alkylphenols (APs), alkylphenols polyethoxylates (APnEOs) and alkylphenoxy carboxylates (APECs) using mixtures of water and organic solvents (i.e. methanol, acetonitrile and tetrahydrofuran) as eluents, in order to obtain their determination by a single LC-MS/MS run. In fact, alkylphenols and alkylphenoxy carboxylates must be analysed in negative ion mode, whereas alkylphenols polyethoxylates undergo ionisation only in positive ion mode, and therefore, two distinct LC-MS/MS analysis are commonly adopted. The best resolution among the aforementioned target analytes was achieved on the pentafluorophenyl column, eluting with an acidified water-acetonitrile-tetrahydrofuran mixture and using the post column addition of an ammonia solution in methanol for the detection of positively ionisable compounds. Under these optimized chromatographic conditions the investigated compounds were determined via a single chromatographic run, with only one polarity switch, in 15min, achieving the following instrumental detection limits: 600pg for AP1EOs, 0.8-14pg for AP2EOs, 10.4-150pg for APs and 4.4-4.8pg for APECs. The chromatographic method was coupled with solid-phase extraction and clean-up procedures and successfully applied to the analysis of wastewater and surface water samples, highlighting mean concentration ranging from 6ng/L for 4-t-OP1EC to 1434ng/L for 4-NP1121EC, depending on the sample analysed. Copyright © 2014 Elsevier B.V. All rights reserved.

  11. Direct quantification of negatively charged functional groups on membrane surfaces

    KAUST Repository

    Tiraferri, Alberto; Elimelech, Menachem

    2012-01-01

    groups at the surface of dense polymeric membranes. Both techniques consist of associating the membrane surface moieties with chemical probes, followed by quantification of the bound probes. Uranyl acetate and toluidine blue O dye, which interact

  12. Multi-walled carbon nanotubes functionalized by carboxylic groups: Activation of TiO{sub 2} (anatase) and phosphate olivines (LiMnPO{sub 4}; LiFePO{sub 4}) for electrochemical Li-storage

    Energy Technology Data Exchange (ETDEWEB)

    Kavan, Ladislav; Zukalova, Marketa [J. Heyrovsky Institute of Physical Chemistry, v.v.i., Academy of Sciences of the Czech Republic, Dolejskova 3, CZ-18223 Prague 8 (Czech Republic); Bacsa, Revathi; Tunckol, Meltem; Serp, Philippe [Laboratoire de Chimie de Coordination, UPR CNRS 8241, composante ENSIACET, Universite de Toulouse UPS-INP-LCC 4, Allee Emile Monso, BP 74233, 31432, Toulouse (France); Zakeeruddin, Shaik M.; Le Formal, Florian; Graetzel, Michael [Laboratoire de Photonique et Interfaces, EPFL, Ecublens, CH-1015 Lausanne (Switzerland)

    2010-08-15

    Multi-walled carbon nanotubes functionalized by carboxylic groups, exhibit better affinity towards TiO{sub 2} (P90, Degussa) as compared to that of pristine nanotubes. Also the electrochemical performance of TiO{sub 2} is improved by nanotube networking, but the Li-storage capacity of TiO{sub 2} is unchanged. Whereas the composite of TiO{sub 2} with non-functionalized nanotubes demonstrates simple superposition of the behavior of pure components, the composite with functionalized nanotubes shows unique faradaic pseudocapacitance which is specific for this composite only. The surface functionalization of nanotubes enhances charge storage capacity and reversibility of a composite with LiMnPO{sub 4} (olivine), but mediates also the electrolyte breakdown at potentials >4.2 V. Whereas the electrochemical activation of LiMnPO{sub 4} (olivine) by functionalized nanotubes is quite modest, excellent performance was found for LiFePO{sub 4} (olivine) in composite materials containing only 2 wt% of functionalized nanotubes. (author)

  13. The influence of pendant carboxylic acid loading on surfaces of statistical poly(4-hydroxystyrene)-co-styrene)s

    DEFF Research Database (Denmark)

    Daugaard, Anders Egede; Hvilsted, Søren

    2008-01-01

    . In particular, aliphatic and aromatic pendant groups differ by 92°C in Tg• Contact angle measurements onspin coated films have shown a maximum effect of the functional groups in the advancing contact angle at a 75/100 copolymer loading. In addition to this, X-ray photoelectron spectroscopy shows the presence...

  14. Photoluminescence effects of graphitic core size and surface functional groups in carbon dots: COO− induced red-shift emission

    KAUST Repository

    Hola, Katerina

    2014-04-01

    We present a simple molecular approach to control the lipophilic/ hydrophilic nature of photoluminescent carbon dots (CDs) based on pyrolysis of alkyl gallate precursors. Depending on the gallic acid derivative used, CDs with different alkyl groups (methyl, propyl, lauryl) on the surface can be obtained by isothermal heating at 270 C. This precursor-derived approach allows not only the control of lipophilicity but also the length of the particular alkyl chain enables the control over both the size and photoluminescence (PL) of the prepared CDs. Moreover, the alkyl chains on the CDs surface can be readily converted to carboxylate groups via a mild base hydrolysis to obtain water dispersible CDs with a record biocompatibility. The observed differences in PL properties of CDs and time-resolved PL data, including contributions from carbogenic cores and surface functional group, are rationalized and discussed in detail using time-dependent density functional theory (TD-DFT) calculations. © 2013 Elsevier Ltd. All rights reserved.

  15. Photoluminescence effects of graphitic core size and surface functional groups in carbon dots: COO− induced red-shift emission

    KAUST Repository

    Hola, Katerina; Bourlinos, Athanasios B.; Kozak, Ondrej; Berka, Karel; Siskova, Karolina M.; Havrdova, Marketa; Tucek, Jiri; Safarova, Klara; Otyepka, Michal; Giannelis, Emmanuel P.; Zboril, Radek

    2014-01-01

    We present a simple molecular approach to control the lipophilic/ hydrophilic nature of photoluminescent carbon dots (CDs) based on pyrolysis of alkyl gallate precursors. Depending on the gallic acid derivative used, CDs with different alkyl groups (methyl, propyl, lauryl) on the surface can be obtained by isothermal heating at 270 C. This precursor-derived approach allows not only the control of lipophilicity but also the length of the particular alkyl chain enables the control over both the size and photoluminescence (PL) of the prepared CDs. Moreover, the alkyl chains on the CDs surface can be readily converted to carboxylate groups via a mild base hydrolysis to obtain water dispersible CDs with a record biocompatibility. The observed differences in PL properties of CDs and time-resolved PL data, including contributions from carbogenic cores and surface functional group, are rationalized and discussed in detail using time-dependent density functional theory (TD-DFT) calculations. © 2013 Elsevier Ltd. All rights reserved.

  16. Hydroxyl group induced adsorption of four-nitro benzoic acid on Si(100) 2x1 surface

    International Nuclear Information System (INIS)

    Ihm, K.; Kang, T.-H.; Hwang, C.C.; Kim, K.-J.; Hwang, H.-N.; Kim, H.-D.; Han, J.H.; Moon, S.; Kim, B.; POSTECH

    2004-01-01

    Full text: A number of studies have been conducted on self-assembled monolayers (SAMs) in order to study the adhesion of polymer films on various substrates. Recently, the studies on SAMs on the semiconductor substrate are more motivated because of their possible application to nanoscale devices. For the electronic and chemical properties suitable for various applications, the aromatic ring has been used as a building block of various molecules forming SAMs. Here, we used four-nitro benzoic acid (4-NBA) as a model planar aromatic compound, in which the phenyl ring, the carboxylic functional group, and NO2 are on the same plane. The adsorption mechanism of 4-NBA on the in-situ prepared OH/Si(100) 2x1 surface was investigated using x-ray photoelectron spectroscopy and near-edge x-ray absorption e structure. The results revealed that the 4-NBA molecule reacts with the hydroxyl group on the Si(100) 2x1 surface through deprotonation of the carboxyl group. The saturation coverage of 4-NBA estimated by the O 1s ratio is 1/2 ML. Additionally, we could observe the desorption of the oxygen atom from the NO2 moiety of the 4-NBA upon irradiating the surface by photons of 500 eV

  17. Theoretical study of chlordecone and surface groups interaction in an activated carbon model under acidic and neutral conditions.

    Science.gov (United States)

    Gamboa-Carballo, Juan José; Melchor-Rodríguez, Kenia; Hernández-Valdés, Daniel; Enriquez-Victorero, Carlos; Montero-Alejo, Ana Lilian; Gaspard, Sarra; Jáuregui-Haza, Ulises Javier

    2016-04-01

    Activated carbons (ACs) are widely used in the purification of drinking water without almost any knowledge about the adsorption mechanisms of the persistent organic pollutants. Chlordecone (CLD, Kepone) is an organochlorinated synthetic compound that has been used mainly as agricultural insecticide. CLD has been identified and listed as a persistent organic pollutant by the Stockholm Convention. The selection of the best suited AC for this type of contaminants is mainly an empirical and costly process. A theoretical study of the influence of AC surface groups (SGs) on CLD adsorption is done in order to help understanding the process. This may provide a first selection criteria for the preparation of AC with suitable surface properties. A model of AC consisting of a seven membered ring graphene sheet (coronene) with a functional group on the edge was used to evaluate the influence of the SGs over the adsorption. Multiple Minima Hypersurface methodology (MMH) coupled with PM7 semiempirical Hamiltonian was employed in order to study the interactions of the chlordecone with SGs (hydroxyl and carboxyl) at acidic and neutral pH and different hydration conditions. Selected structures were re-optimized using CAM-B3LYP to achieve a well-defined electron density to characterize the interactions by the Quantum Theory of Atoms in Molecules approach. The deprotonated form of surface carboxyl and hydroxyl groups of AC models show the strongest interactions, suggesting a chemical adsorption. An increase in carboxylic SGs content is proposed to enhance CLD adsorption onto AC at neutral pH conditions. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. High-Performance Supercapacitor of Functionalized Carbon Fiber Paper with High Surface Ionic and Bulk Electronic Conductivity: Effect of Organic Functional Groups

    International Nuclear Information System (INIS)

    Suktha, Phansiri; Chiochan, Poramane; Iamprasertkun, Pawin; Wutthiprom, Juthaporn; Phattharasupakun, Nutthaphon; Suksomboon, Montakan; Kaewsongpol, Tanon; Sirisinudomkit, Pichamon; Pettong, Tanut; Sawangphruk, Montree

    2015-01-01

    Highlights: • A supercapacitor of organic functionalized carbon fiber paper (f-CFP) exhibits high areal and volumetric capacitances. • The performance of the supercapacitor depends on the organic functional group on the surface of the f-CFP. • Hydroxyl and carboxylic groups modified on the surface of f-CFP have higher pseudocapacitive property than amide and amine functional groups. • The f-CFP exhibits high surface ionic and bulk electrical conductivities. - Abstract: Although carbon fiber paper (CFP) or nonwovens are widely used as a non-corrosive and conductive substrate or current collector in batteries and supercapacitors as well as a gas diffusion layer in proton exchange membrane fuel cells, the CFP cannot store charges due to its poor ionic conductivity and its hydrophobic surface. In this work, the chemically functionalized CFP (f-CFP) consisting of hydroxyl and carboxylic groups on its surface was produced by an oxidation reaction of CFP in a mixed concentrated acid solution of H 2 SO 4 :HNO 3 (3:1 v/v) at 60 °C for 1 h. Other amide and amine groups modified CFP were also synthesized for comparison using a dehydration reaction of carboxylic modified CFP with ethylenediamine and n-butylamine. Interestingly, it was found that hydroxyl and carboxylic groups modified CFP behave as a pseudocapacitor electrode, which can store charges via the surface redox reaction in addition to electrochemical double layer capacitance. The aqueous-based supercapacitor of f-CFP has high areal, volumetric, and specific energy (49.0 μW.h/cm 2 , 1960 mW.h/L, and 5.2 W.h/Kg) and power (3.0 mW/cm 2 , 120 W/L, and 326.2 W/Kg) based on the total geometrical surface area and volume as well as the total weight of positive and negative electrodes. High charge capacity of the f-CFP stems from high ionic charge and pseudocapacitive behavior due to hydroxyl and carboxylic groups on its surface and high bulk electronic conductivity (2.03 mS/cm) due to 1D carbon fiber paper. The

  19. Reaction of Nα-acetyl-L-histidine with diazomethane: A model esterification reaction of carboxylic groups in the presence of imidazole rings

    Directory of Open Access Journals (Sweden)

    Zamora, R.

    1996-10-01

    Full Text Available The reaction of Nα-acetyl-L-histidine with diazomethane was studied in order to analyze the esterification reaction of a carboxylic group in the presence of an imidazole ring. The reaction produced the expected Nα-acetyl-L-histidine methyl ester (1 as a major product. However, important amounts of [S]-acetyl-1-methylimidazole-4-alanine methyl ester (2 and [S]-acetyl-1-methylimidazole-5-alanine methyl ester (3 were also produced. These compounds, which could be detected by capillary electrophoresis (HPCE and thin layer chromatography, were fractionated by column chromatography and identified by gas chromatography coupled with mass spectrometry (GC-MS, and 1H and 13C nuclear magnetic resonance spectroscopy. Structures for compounds 1-3 were confirmed by HPCE after acid hydrolysis. These results indicated that the use of diazomethane produces the methyl derivative of the heterocyclic ring in addition to the methyl ester. This reaction should be considered when preparing derivatives for GC-MS analysis.

    La reacción de la Nα-acetil-L-histidina con diazometano fue estudiada con objeto de conocer el comportamiento de la reacción de esterificación de un grupo carboxílico en presencia de un anillo de imidazol. La reacción produjo el esperado éster metílico de la Nα-acetil-L-histidina (1 como producto mayoritario. Sin embargo, también se observó la formación de cantidades importantes de los esteres metílicos de la [S]-acetil-1-metilimidazol- 4-alanina (2 y la [S]-acetil-1-metilimidazol-5-alanina (3. Estos compuestos que pudieron ser detectados por electroforesis capilar y cromatografía en capa fina, fueron separados por cromatografía en columna e identificados por cromatografía de gases acoplada a espectrometría de masas, y por espectroscopia de resonancia magnética nuclear de 1H y 13C. Las estructuras de los compuestos

  20. Simultaneous Decolorization and Biohydrogen Production from Xylose by Klebsiella oxytoca GS-4-08 in the Presence of Azo Dyes with Sulfonate and Carboxyl Groups

    Science.gov (United States)

    Cao, Ming-yue; Wang, Peng-tao; Wang, Shi; Yue, Ying-rong; Yuan, Wen-duo; Qiao, Wei-chuan; Wang, Fei

    2017-01-01

    ABSTRACT Biohydrogen production from the pulp and paper effluent containing rich lignocellulosic material could be achieved by the fermentation process. Xylose, an important hemicellulose hydrolysis product, is used less efficiently as a substrate for biohydrogen production. Moreover, azo dyes are usually added to fabricate anticounterfeiting paper, which further increases the complexity of wastewater. This study reports that xylose could serve as the sole carbon source for a pure culture of Klebsiella oxytoca GS-4-08 to achieve simultaneous decolorization and biohydrogen production. With 2 g liter−1 of xylose as the substrate, a maximum xylose utilization rate (URxyl) and a hydrogen molar yield (HMY) of 93.99% and 0.259 mol of H2 mol of xylose−1, respectively, were obtained. Biohydrogen kinetics and electron equivalent (e− equiv) balance calculations indicated that methyl red (MR) penetrates and intracellularly inhibits both the pentose phosphate pathway and pyruvate fermentation pathway, while methyl orange (MO) acted independently of the glycolysis and biohydrogen pathway. The data demonstrate that biohydrogen pathways in the presence of azo dyes with sulfonate and carboxyl groups were different, but the azo dyes could be completely reduced during the biohydrogen production period in the presence of MO or MR. The feasibility of hydrogen production from industrial pulp and paper effluent by the strain if the xylose is sufficient was also proved and was not affected by toxic substances which usually exist in such wastewater, except for chlorophenol. This study offers a promising energy-recycling strategy for treating pulp and paper wastewaters, especially for those containing azo dyes. IMPORTANCE The pulp and paper industry is a major industry in many developing countries, and the global market of pulp and paper wastewater treatment is expected to increase by 60% between 2012 and 2020. Such wastewater contains large amounts of refractory contaminants, such

  1. A spin-crossover complex based on a 2,6-bis(pyrazol-1-yl)pyridine (1-bpp) ligand functionalized with a carboxylate group.

    Science.gov (United States)

    Abhervé, Alexandre; Clemente-León, Miguel; Coronado, Eugenio; Gómez-García, Carlos J; López-Jordà, Maurici

    2014-07-07

    Combining Fe(ii) with the carboxylate-functionalized 2,6-bis(pyrazol-1-yl)pyridine (bppCOOH) ligand results in the spin-crossover compound [Fe(bppCOOH)2](ClO4)2 which shows an abrupt spin transition with a T1/2 of ca. 380 K and a TLIESST of 60 K due to the presence of a hydrogen-bonded linear network of complexes.

  2. Emission of perfluoroalkyl carboxylic acids (PFCA) from heated surfaces made of polytetrafluoroethylene (PTFE) applied in food contact materials and consumer products.

    Science.gov (United States)

    Schlummer, Martin; Sölch, Christina; Meisel, Theresa; Still, Mona; Gruber, Ludwig; Wolz, Gerd

    2015-06-01

    Polytetrafluoroethylene (PTFE) has been widely discussed as a source of perfluorooctanoic acid (PFOA), which has been used in the production of fluoropolymers. PTFE may also contain unintended perfluoroalkyl carboxylic acids (PFCAs) caused by thermolysis of PTFE, which has been observed at temperatures above 300°C. Common PTFE coated food contact materials and consumer goods are operated at temperatures above 200°C. However, knowledge on possible emissions of PFCAs is limited. Therefore, it was the aim of this study to investigate and evaluate the emission of PFCAs from PTFE coated products with both, normal use and overheating scenarios. Four pans, claimed to be PFOA free, and nine consumer products were investigated. At normal use conditions (PTFE surfaces were trapped for 1h. Overheating scenarios (>260°C) recorded emissions during a 30min heating of empty pans on a stove. Emissions were analyzed by LC-ESI-MS. Results indicate the emission of PFCAs, whereas no perfluorinated sulfonic acids were traced. At normal use conditions total emissions of PFCAs accounted for 4.75ng per hour. Overheated pans, however, released far higher amounts with up to 12190ng PFCAs per hour at 370°C. Dominating contributors where PFBA and PFOA at normal use and PFBA and PFPeA during overheating. Temperature seems to be the main factor controlling the emission of PFCAs. A worst case estimation of human exposure revealed that emissions of PFCAs from heated PTFE surfaces would be far below the TDI of 1500ng PFOA per kg body weight. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Carboxylated SiO2-coated α-Fe nanoparticles: towards a versatile platform for biomedical applications.

    Science.gov (United States)

    Kohara, Kaori; Yamamoto, Shinpei; Seinberg, Liis; Murakami, Tatsuya; Tsujimoto, Masahiko; Ogawa, Tetsuya; Kurata, Hiroki; Kageyama, Hiroshi; Takano, Mikio

    2013-03-28

    Carboxylated SiO2-coated α-Fe nanoparticles have been successfully prepared via CaH2-mediated reduction of SiO2-coated Fe3O4 nanoparticles followed by surface carboxylation. These α-Fe-based nanoparticles, which are characterized by ease of coating with additional functional groups, a large magnetization of 154 emu per g-Fe, enhanced corrosion resistivity, excellent aqueous dispersibility, and low cytotoxicity, have potential to be a versatile platform in biomedical applications.

  4. Intersections of adelic groups on a surface

    International Nuclear Information System (INIS)

    Budylin, R Ya; Gorchinskiy, S O

    2013-01-01

    We solve a technical problem related to adeles on an algebraic surface. Given a finite set of natural numbers, one can associate with it an adelic group. We show that this operation commutes with taking intersections if the surface is defined over an uncountable field, and we provide a counterexample otherwise. Bibliography: 12 titles

  5. Are carboxyl groups the most acidic sites in amino acids? Gas-phase acidities, photoelectron spectra, and computations on tyrosine, p-hydroxybenzoic acid, and their conjugate bases.

    Science.gov (United States)

    Tian, Zhixin; Wang, Xue-Bin; Wang, Lai-Sheng; Kass, Steven R

    2009-01-28

    Deprotonation of tyrosine in the gas phase was found to occur preferentially at the phenolic site, and the conjugate base consists of a 70:30 mixture of phenoxide and carboxylate anions at equilibrium. This result was established by developing a chemical probe for differentiating these two isomers, and the presence of both ions was confirmed by photoelectron spectroscopy. Equilibrium acidity measurements on tyrosine indicated that deltaG(acid)(o) = 332.5 +/- 1.5 kcal mol(-1) and deltaH(acid)(o) = 340.7 +/- 1.5 kcal mol(-1). Photoelectron spectra yielded adiabatic electron detachment energies of 2.70 +/- 0.05 and 3.55 +/- 0.10 eV for the phenoxide and carboxylate anions, respectively. The H/D exchange behavior of deprotonated tyrosine was examined using three different alcohols (CF3CH2OD, C6H5CH2OD, and CH3CH2OD), and incorporation of up to three deuterium atoms was observed. Two pathways are proposed to account for these results, and all of the experimental findings are supplemented with B3LYP/aug-cc-pVDZ and G3B3 calculations. In addition, it was found that electrospray ionization of tyrosine from a 3:1 (v/v) CH3OH/H2O solution using a commercial source produces a deprotonated [M-H]- anion with the gas-phase equilibrium composition rather than the structure of the ion that exists in aqueous media. Electrospray ionization from acetonitrile, however, leads largely to the liquid-phase (carboxylate) structure. A control molecule, p-hydroxybenzoic acid, was found to behave in a similar manner. Thus, the electrospray conditions that are employed for the analysis of a compound can alter the isomeric composition of the resulting anion.

  6. Acid-base titrations of functional groups on the surface of the thermophilic bacterium Anoxybacillus flavithermus: comparing a chemical equilibrium model with ATR-IR spectroscopic data.

    Science.gov (United States)

    Heinrich, Hannah T M; Bremer, Phil J; Daughney, Christopher J; McQuillan, A James

    2007-02-27

    Acid-base functional groups at the surface of Anoxybacillus flavithermus (AF) were assigned from the modeling of batch titration data of bacterial suspensions and compared with those determined from in situ infrared spectroscopic titration analysis. The computer program FITMOD was used to generate a two-site Donnan model (site 1: pKa = 3.26, wet concn = 2.46 x 10(-4) mol g(-1); site 2: pKa = 6.12, wet concn = 6.55 x 10(-5) mol g(-1)), which was able to describe data for whole exponential phase cells from both batch acid-base titrations at 0.01 M ionic strength and electrophoretic mobility measurements over a range of different pH values and ionic strengths. In agreement with information on the composition of bacterial cell walls and a considerable body of modeling literature, site 1 of the model was assigned to carboxyl groups, and site 2 was assigned to amino groups. pH difference IR spectra acquired by in situ attenuated total reflection infrared (ATR-IR) spectroscopy confirmed the presence of carboxyl groups. The spectra appear to show a carboxyl pKa in the 3.3-4.0 range. Further peaks were assigned to phosphodiester groups, which deprotonated at slightly lower pH. The presence of amino groups could not be confirmed or discounted by IR spectroscopy, but a positively charged group corresponding to site 2 was implicated by electrophoretic mobility data. Carboxyl group speciation over a pH range of 2.3-10.3 at two different ionic strengths was further compared to modeling predictions. While model predictions were strongly influenced by the ionic strength change, pH difference IR data showed no significant change. This meant that modeling predictions agreed reasonably well with the IR data for 0.5 M ionic strength but not for 0.01 M ionic strength.

  7. Decarboxylative Trifluoromethylation of Aliphatic Carboxylic Acids.

    Science.gov (United States)

    Kautzky, Jacob A; Wang, Tao; Evans, Ryan W; MacMillan, David W C

    2018-05-14

    Herein we disclose an efficient method for the conversion of carboxylic acids to trifluoromethyl groups via the combination of photoredox and copper catalysis. This transformation tolerates a wide range of functionality including heterocycles, olefins, alcohols, and strained ring systems. To demonstrate the broad potential of this new methodology for late-stage functionalization, we successfully converted a diverse array of carboxylic acid-bearing natural products and medicinal agents to the corresponding trifluoromethyl analogues.

  8. Riemann surfaces, Clifford algebras and infinite dimensional groups

    International Nuclear Information System (INIS)

    Carey, A.L.; Eastwood, M.G.; Hannabuss, K.C.

    1990-01-01

    We introduce of class of Riemann surfaces which possess a fixed point free involution and line bundles over these surfaces with which we can associate an infinite dimensional Clifford algebra. Acting by automorphisms of this algebra is a 'gauge' group of meromorphic functions on the Riemann surface. There is a natural Fock representation of the Clifford algebra and an associated projective representation of this group of meromorphic functions in close analogy with the construction of the basic representation of Kac-Moody algebras via a Fock representation of the Fermion algebra. In the genus one case we find a form of vertex operator construction which allows us to prove a version of the Boson-Fermion correspondence. These results are motivated by the analysis of soliton solutions of the Landau-Lifshitz equation and are rather distinct from recent developments in quantum field theory on Riemann surfaces. (orig.)

  9. Theoretical study of γ-hexachlorocyclohexane and β-hexachlorocyclohexane isomers interaction with surface groups of activated carbon model.

    Science.gov (United States)

    Enriquez-Victorero, Carlos; Hernández-Valdés, Daniel; Montero-Alejo, Ana Lilian; Durimel, Axelle; Gaspard, Sarra; Jáuregui-Haza, Ulises

    2014-06-01

    Activated carbon (AC) is employed in drinking water purification without almost any knowledge about the adsorption mechanism of persistent organic pollutants (POPs) onto it. Hexachlorocyclohexane (HCH) is an organochlorinated contaminant present in water and soils of banana crops production zones of the Caribbean. The most relevant isomers of HCH are γ-HCH and β-HCH, both with great environmental persistence. A theoretical study of the influence of AC surface groups (SGs) on HCH adsorption is done in order to help to understand the process and may lead to improve the AC selection process. A simplified AC model consisting of naphthalene with a functional group was used to assess the influence of SGs over the adsorption process. The Multiple Minima Hypersurface (MMH) methodology was employed to study γ-HCH and β-HCH interactions with different AC SGs (hydroxyl and carboxyl) under different hydration and pH conditions. The results obtained showed that association of HCH with SGs preferentially occurs between the axial protons of HCH and SG's oxygen atom, and the most favorable interactions occurring with charged SGs. An increase in carboxylic SGs content is proposed to enhance HCH adsorption onto AC under neutral pH conditions. Finally, this work presents an inexpensive computer aided methodology for preselecting activated carbon SGs content for the removal of a given compound. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Direct quantification of negatively charged functional groups on membrane surfaces

    KAUST Repository

    Tiraferri, Alberto

    2012-02-01

    Surface charge plays an important role in membrane-based separations of particulates, macromolecules, and dissolved ionic species. In this study, we present two experimental methods to determine the concentration of negatively charged functional groups at the surface of dense polymeric membranes. Both techniques consist of associating the membrane surface moieties with chemical probes, followed by quantification of the bound probes. Uranyl acetate and toluidine blue O dye, which interact with the membrane functional groups via complexation and electrostatic interaction, respectively, were used as probes. The amount of associated probes was quantified using liquid scintillation counting for uranium atoms and visible light spectroscopy for the toluidine blue dye. The techniques were validated using self-assembled monolayers of alkanethiols with known amounts of charged moieties. The surface density of negatively charged functional groups of hand-cast thin-film composite polyamide membranes, as well as commercial cellulose triacetate and polyamide membranes, was quantified under various conditions. Using both techniques, we measured a negatively charged functional group density of 20-30nm -2 for the hand-cast thin-film composite membranes. The ionization behavior of the membrane functional groups, determined from measurements with toluidine blue at varying pH, was consistent with published data for thin-film composite polyamide membranes. Similarly, the measured charge densities on commercial membranes were in general agreement with previous investigations. The relative simplicity of the two methods makes them a useful tool for quantifying the surface charge concentration of a variety of surfaces, including separation membranes. © 2011 Elsevier B.V.

  11. Surface functional groups in capacitive deionization with porous carbon electrodes

    Science.gov (United States)

    Hemmatifar, Ali; Oyarzun, Diego I.; Palko, James W.; Hawks, Steven A.; Stadermann, Michael; Santiago, Juan G.; Stanford Microfluidics Lab Team; Lawrence Livermore National Lab Team

    2017-11-01

    Capacitive deionization (CDI) is a promising technology for removal of toxic ions and salt from water. In CDI, an applied potential of about 1 V to pairs of porous electrodes (e.g. activated carbon) induces ion electromigration and electrostatic adsorption at electrode surfaces. Immobile surface functional groups play a critical role in the type and capacity of ion adsorption, and this can dramatically change desalination performance. We here use models and experiments to study weak electrolyte surface groups which protonate and/or depropotante based on their acid/base dissociation constants and local pore pH. Net chemical surface charge and differential capacitance can thus vary during CDI operation. In this work, we present a CDI model based on weak electrolyte acid/base equilibria theory. Our model incorporates preferential cation (anion) adsorption for activated carbon with acidic (basic) surface groups. We validated our model with experiments on custom built CDI cells with a variety of functionalizations. To this end, we varied electrolyte pH and measured adsorption of individual anionic and cationic ions using inductively coupled plasma mass spectrometry (ICP-MS) and ion chromatography (IC) techniques. Our model shows good agreement with experiments and provides a framework useful in the design of CDI control schemes.

  12. A facile and novel approach towards carboxylic acid functionalization of multiwalled carbon nanotubes and efficient water dispersion

    KAUST Repository

    Rehman, Ata Ur

    2013-10-01

    A convenient, cheap and mild covalent functionalization route for multiwalled carbon nanotubes (MWCNTs) have been developed for the first time. The MWCNTs were treated with wet chemical oxidants (NaNO2/HCl, HNO3/H2O2) in order to modify MWCNTs with carboxyl groups. Surface functionality groups and morphology of MWCNTs were analyzed by FTIR, TGA, SEM and TEM. The results consistently confirmed the formation of carboxyl functionalities on MWCNTs, while the structure of MWCNTs has remained relatively intact. Functionalized MWCNTs showed good dispersion in aqueous media than untreated MWCNTs. Results show that NaNO2/HCl treatment is best suited for the chemical functionalization, giving optimum surface carboxyl groups and minimum length shortening of MWCNTs. © 2013 Elsevier B.V.

  13. A facile and novel approach towards carboxylic acid functionalization of multiwalled carbon nanotubes and efficient water dispersion

    KAUST Repository

    Rehman, Ata Ur; Abbas, Syed Mustansar; Ammad, Hafiz Muhammad; Badshah, Amin; Ali, Zulfiqar; Anjum, Dalaver H.

    2013-01-01

    A convenient, cheap and mild covalent functionalization route for multiwalled carbon nanotubes (MWCNTs) have been developed for the first time. The MWCNTs were treated with wet chemical oxidants (NaNO2/HCl, HNO3/H2O2) in order to modify MWCNTs with carboxyl groups. Surface functionality groups and morphology of MWCNTs were analyzed by FTIR, TGA, SEM and TEM. The results consistently confirmed the formation of carboxyl functionalities on MWCNTs, while the structure of MWCNTs has remained relatively intact. Functionalized MWCNTs showed good dispersion in aqueous media than untreated MWCNTs. Results show that NaNO2/HCl treatment is best suited for the chemical functionalization, giving optimum surface carboxyl groups and minimum length shortening of MWCNTs. © 2013 Elsevier B.V.

  14. Uranium (IV) carboxylates - I

    Energy Technology Data Exchange (ETDEWEB)

    Satpathy, K C; Patnaik, A K [Sambalpur Univ. (India). Dept. of Chemistry

    1975-11-01

    A few uranium(IV) carboxylates with monochloro and trichloro acetic acid, glycine, malic, citric, adipic, o-toluic, anthranilic and salicylic acids have been prepared by photolytic methods. The I.R. spectra of these compounds are recorded and basing on the spectral data, structure of the compounds have been suggested.

  15. Modification of dispersibility of nanodiamond by grafting of polyoxyethylene and by the introduction of ionic groups onto the surface via radical trapping

    International Nuclear Information System (INIS)

    Cha, I.; Hashimoto, K.; Fujiki, K.; Yamauchi, T.; Tsubokawa, N.

    2014-01-01

    To improve the dispersibility of polycrystalline nanodiamond (ND) in solvents, the grafting of polymers and introduction of ionic groups onto ND surface via radical trapping by ND surface were investigated. The grafting of polyoxyethylene (POE) onto ND surface by trapping of POE radicals formed by the thermal decomposition of POE macro azo-initiator (Azo-POE) was examined. The polymer radicals formed by the thermal decomposition of Azo-POE were successfully trapped by ND surface to give POE-grafted ND. The effect of temperature on the grafting of POE onto ND was discussed. In addition, the introduction of cationic protonated amidine groups onto ND was achieved by the trapping of radicals bearing protonated amidine groups formed by thermal decomposition of 2,2′-azobis(2-methylpropionamidine)dihydrochloride (AMPA). The anionic carboxylate groups was introduced onto ND surface by the trapping of the radicals bearing carboxyl groups formed by thermal decomposition of 4,4′-azobis(4-cyonovaleric acid) (ACVA) followed by the treatment with NaOH aqueous solution. The dispersibility of ND in water was remarkably improved by the grafting of POE, based on the steric hindrance of polymer chains and by the introduction of ionic groups, based on the ionic repulsion, onto ND surface. - Highlights: • Grafting of PEG onto nanodiamond was achieved by radical trapping. • Introduction of ionic groups onto nanodiamond was achieved by radical trapping. • Nanodiamond was dispersed by PEG grafting based on steric hindrance of PEG chains. • Nanodiamond was dispersed by introduction of ionic groups based on ionic repulsion

  16. Modification of dispersibility of nanodiamond by grafting of polyoxyethylene and by the introduction of ionic groups onto the surface via radical trapping

    Energy Technology Data Exchange (ETDEWEB)

    Cha, I. [Graduate School of Science and Technology, Niigata University, 8050, Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-2181 (Japan); Hashimoto, K. [Department of Material Science and Technology, Faculty of Engineering, Niigata University, 8050, Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-218 (Japan); Fujiki, K. [Department of Environmental Science, Niigata Institute of Technology, 1719, Fujihashi, Kashiwazaki, Niigata 945-1195 (Japan); Yamauchi, T. [Graduate School of Science and Technology, Niigata University, 8050, Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-2181 (Japan); Department of Material Science and Technology, Faculty of Engineering, Niigata University, 8050, Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-218 (Japan); Tsubokawa, N., E-mail: ntsuboka@eng.niigata-u.ac.jp [Graduate School of Science and Technology, Niigata University, 8050, Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-2181 (Japan); Department of Material Science and Technology, Faculty of Engineering, Niigata University, 8050, Ikarashi, 2-no-cho, Nishi-ku, Niigata 950-218 (Japan)

    2014-02-14

    To improve the dispersibility of polycrystalline nanodiamond (ND) in solvents, the grafting of polymers and introduction of ionic groups onto ND surface via radical trapping by ND surface were investigated. The grafting of polyoxyethylene (POE) onto ND surface by trapping of POE radicals formed by the thermal decomposition of POE macro azo-initiator (Azo-POE) was examined. The polymer radicals formed by the thermal decomposition of Azo-POE were successfully trapped by ND surface to give POE-grafted ND. The effect of temperature on the grafting of POE onto ND was discussed. In addition, the introduction of cationic protonated amidine groups onto ND was achieved by the trapping of radicals bearing protonated amidine groups formed by thermal decomposition of 2,2′-azobis(2-methylpropionamidine)dihydrochloride (AMPA). The anionic carboxylate groups was introduced onto ND surface by the trapping of the radicals bearing carboxyl groups formed by thermal decomposition of 4,4′-azobis(4-cyonovaleric acid) (ACVA) followed by the treatment with NaOH aqueous solution. The dispersibility of ND in water was remarkably improved by the grafting of POE, based on the steric hindrance of polymer chains and by the introduction of ionic groups, based on the ionic repulsion, onto ND surface. - Highlights: • Grafting of PEG onto nanodiamond was achieved by radical trapping. • Introduction of ionic groups onto nanodiamond was achieved by radical trapping. • Nanodiamond was dispersed by PEG grafting based on steric hindrance of PEG chains. • Nanodiamond was dispersed by introduction of ionic groups based on ionic repulsion.

  17. Mass spectrometric behaviour of carboxylated polyethylene glycols and carboxylated octylphenol ethoxylates.

    Science.gov (United States)

    Frańska, Magdalena; Zgoła, Agnieszka; Rychłowska, Joanna; Szymański, Andrzej; Łukaszewski, Zenon; Frański, Rafał

    2003-01-01

    Mass spectrometric behaviour of mono- and di-carboxylated polyethylene glycols (PEGCs and CPEGCs) and carboxylated octylphenol ethoxylates (OPECs) are discussed. The tendency for ionisation (deprotonation, protonation and cationisation by alkali metal cations) of carboxylated PEGs was compared with that of non-carboxylated correspondents by using both secondary ion mass spectrometry (SIMS) and electrospray ionisation (ESI). The fragmentation of the PEGCs and CPEGCs is discussed and also compared with their neutral correspondents, PEGs. The B/E mass spectra were recorded, using secondary ion mass spectrometry as a method for generation, for deprotonated and protonated molecules and molecules cationised by alkali metal cations. The fragmentation behaviour of PEGs is found to be different from that of CPEGCs, The presence of carboxylic groups may be confirmed not only by the determination of molecular weights of the ethoxylates studied, but also on the basis of the fragment ions formed. The metastable decomposition of the [OPEC-H](-) ions proceed through the cleavage of the bond between the octylphenol moiety and the ethoxylene chain leading to the octylphenoxy anions. It permits determination of the mass of the hydrophobic moiety of the studied carboxylated alkylphenol ethoxylate. ESI mass spectra recorded in the negative ion mode were found to be more suitable for the determination of the average molecular weight of carboxylated ethoxylates than SI mass spectra.

  18. Interaction between the surface of the silver nanoparticles prepared by γ-irradiation and organic molecules containing thiol group

    International Nuclear Information System (INIS)

    Choi, S.-H.; Lee, S.-H.; Hwang, Y.-M.; Lee, K.-P.; Kang, H.-D.

    2003-01-01

    The colloidal silver nanoparticles were prepared by the γ-irradiation of silver nitrate (AgNO 3 ) in a mixture solution of water and 2-propanol in the presence of poly(vinylpyrrolidone) as a colloidal stabilizer. The Ag colloids obtained by γ-irradiation were characterized by use of XRD and TEM. The surface of the Ag colloids were modified by use of mercaptosuccinic acid (MSA), (D)-cysteine (Cys), and (L)-Cys, respectively. The MSA and (L)-Cys-capped Ag colloids were aggregated because of hydrogen bonding of the carboxylic acid and amino acid group, respectively. From the analysis by CD spectroscopy, it was shown that chiral-enhanced phenomena were obtained in (L)- and (D)-Cys-capped Ag colloids

  19. Novel Polymers with Carboxylic Acid Loading

    DEFF Research Database (Denmark)

    Thomsen, Anders Daugaard; Malmström, Eva; Hvilsted, Søren

    2006-01-01

    Click chemistry has been used to prepare a range of novel polymers with pendant carboxylic acid side groups. Four azido carboxylic acids, either mono- or difunctional and aliphatic or aromatic, have been prepared and thoroughly characterized. Extensive model reactions with 1-ethyl-4-hydroxybenzene......, the simplest model for poly(4-hydroxystyrene), and the four azido carboxylic acids have been conducted to establish the proper reaction conditions and provide an analytical frame for the corresponding polymers. Poly(4-hydroxystyrene) moieties in three different polymers—poly(4-hydroxystyrene), poly(4...... the polymers in general exhibit [when poly(4-hydroxystyrene) is a substantial part] significant changes in the glass-transition temperature from the polar poly(4-hydroxystyrene) (120–130 °C) to the much less polar alkyne polymers (46–60 °C). A direct correlation between the nature of the pendant groups...

  20. Carboxylic acid-functionalized SBA-15 nanorods for gemcitabine delivery

    International Nuclear Information System (INIS)

    Bahrami, Zohreh; Badiei, Alireza; Ziarani, Ghodsi Mohammadi

    2015-01-01

    The present study deals with the functionalization of mesoporous silica nanoparticles as drug delivery systems. Mono, di, and tri amino-functionalized SBA-15 nanorods were synthesized by post-grafting method using (3-aminopropyl) triethoxysilane, N-(2-aminoethyl-)3- aminopropyltrimethoxysilane, and 3-[2-(2-aminoethylamino) ethylamino] propyl trimethoxysilane, respectively. The carboxylic acid derivatives of the amino-functionalized samples were obtained using succinic anhydride. Tminopropyltrimethoxysilanehe obtained modified materials were investigated as matrixes for the anticancer drug (gemcitabine) delivery. The prepared samples were characterized by SAXS, N 2 adsorption/desorption, SEM, transmission electron microscopy, thermogravimetric analysis, and FTIR and UV spectroscopies. The adsorption and release properties of all samples were studied. It was revealed that the adsorption capacity and release behavior of gemcitabine were highly dependent on the type of the introduced functional groups. The carboxylic acid-modified samples have higher loading content, due to the strong interaction with gemcitabine. The maximum content of deposited drug in the modified SBA-15 nanorods is close to 40 wt%. It was found that the surface functionalization leads toward significant decrease of the drug release rate. The carboxylic acid-functionalized samples have slower release rate in contrast with the amino-functionalized samples

  1. First principles study of edge carboxylated graphene quantum dots

    Science.gov (United States)

    Abdelsalam, Hazem; Elhaes, Hanan; Ibrahim, Medhat A.

    2018-05-01

    The structure stability and electronic properties of edge carboxylated hexagonal and triangular graphene quantum dots are investigated using density functional theory. The calculated binding energies show that the hexagonal clusters with armchair edges have the highest stability among all the quantum dots. The binding energy of carboxylated graphene quantum dots increases by increasing the number of carboxyl groups. Our study shows that the total dipole moment significantly increases by adding COOH with the highest value observed in triangular clusters. The edge states in triangular graphene quantum dots with zigzag edges produce completely different energy spectrum from other dots: (a) the energy gap in triangular zigzag is very small as compared to other clusters and (b) the highest occupied molecular orbital is localized at the edges which is in contrast to other clusters where it is distributed over the cluster surface. The enhanced reactivity and the controllable energy gap by shape and edge termination make graphene quantum dots ideal for various nanodevice applications such as sensors. The infrared spectra are presented to confirm the stability of the quantum dots.

  2. The Measurement and Interpretation of Surface Wave Group Arrival Times

    Science.gov (United States)

    Masters, G.; Kane, D.; Morrow, J.; Zhou, Y.; Tromp, J.

    2005-12-01

    We have recently developed an efficient technique for measuring the relative group arrival times of surface waves by using cross-correlation and cluster analysis of waveform envelope functions. Applying the analysis to minor arc Love and Rayleigh waves in the frequency band 7 to 35 mHz for all events over magnitude 5.5 results in a dataset of over 200,000 measurements at each frequency for long period Rayleigh waves (frequency less than 25 mHz) and about 100,000 measurements at the shorter periods. Analysis of transverse components results in about half as many Love wave measurements. Simple ray theory inversions of the relative arrival times for apparent group velocity produce maps which are accurate representations of the data (often over 90% variance reduction of the relative arrival times) and which show features strongly correlated with tectonics and crustal thickness. The apparent group velocity variations can be extremely large: 30% velocity variations for 20 mHz Rayleigh waves and 40% variations for 30 mHz Rayleigh waves and can have abrupt lateral changes. This raises the concern that non-ray theory effects could be important. Indeed, a recent analysis by Dahlen and Zhou (personal communication) suggests that the group arrival times should be a functions of both the group velocity AND the phase velocity. The simplest way to test the interpretation of the measurements is to perform the analysis on synthetic seismograms computed for a realistic model of the Earth. Here, we use the SEM with a model which incorporates realistic crust and mantle structure. We are currently computing synthetics for a suite of roughly 1000 events recorded globally that extend to a period of 18 seconds. We shall present the results of applying both ray-based and finite frequency inversions to the synthetic data as well as evaluating the effects of off path propagation at short periods using surface wave ray tracing.

  3. Integrable systems twistors, loop groups, and Riemann surfaces

    CERN Document Server

    Hitchin, NJ; Ward, RS

    2013-01-01

    This textbook is designed to give graduate students an understanding of integrable systems via the study of Riemann surfaces, loop groups, and twistors. The book has its origins in a series of lecture courses given by the authors, all of whom are internationally known mathematicians and renowned expositors. It is written in an accessible and informal style, and fills a gap in the existing literature. The introduction by Nigel Hitchin addresses the meaning of integrability: how do werecognize an integrable system? His own contribution then develops connections with algebraic geometry, and inclu

  4. 2-Isopropyl-5-methylcyclohexyl quinoline-2-carboxylate

    Directory of Open Access Journals (Sweden)

    E. Fazal

    2014-01-01

    Full Text Available In the title compound, C20H25NO2, the cyclohexyl ring adopts a slightly disordered chair conformation. The dihedral angle between the mean planes of the quinoline ring and the carboxylate group is 22.2 (6°. In the crystal, weak C—H...N interactions make chains along [010].

  5. Nano-graphene oxide carboxylation for efficient bioconjugation applications: a quantitative optimization approach

    Science.gov (United States)

    Imani, Rana; Emami, Shahriar Hojjati; Faghihi, Shahab

    2015-02-01

    A method for carboxylation of graphene oxide (GO) with chloroacetic acid that precisely optimizes and controls the efficacy of the process for bioconjugation applications is proposed. Quantification of COOH groups on nano-graphene oxide sheets (NGOS) is performed by novel colorimetric methylene blue (MB) assay. The GO is synthesized and carboxylated by chloroacetic acid treatment under strong basic condition. The size and morphology of the as-prepared NGOS are characterized by scanning electron microscopy, transmission electron microscopy (TEM), and atomic force microscopy (AFM). The effect of acid to base molar ratio on the physical, chemical, and morphological properties of NGOS is analyzed by Fourier-transformed infrared spectrometry (FTIR), UV-Vis spectroscopy, X-ray diffraction (XRD), AFM, and zeta potential. For evaluation of bioconjugation efficacy, the synthesized nano-carriers with different carboxylation ratios are functionalized by octaarginine peptide sequence (R8) as a biomolecule model containing amine groups. The quantification of attached R8 peptides to graphene nano-sheets' surface is performed with a colorimetric-based assay which includes the application of 2,4,6-Trinitrobenzene sulfonic acid (TNBS). The results show that the thickness and lateral size of nano-sheets are dramatically decreased to 0.8 nm and 50-100 nm after carboxylation process, respectively. X-ray analysis shows the nano-sheets interlaying space is affected by the alteration of chloroacetic acid to base ratio. The MB assay reveals that the COOH groups on the surface of NGOS are maximized at the acid to base ratio of 2 which is confirmed by FTIR, XRD, and zeta potential. The TNBS assay also shows that bioconjugation of the optimized carboxylated NGOS sample with octaarginine peptide is 2.5 times more efficient compared to bare NGOS. The present work provides evidence that treatment of GO by chloroacetic acid under an optimized condition would create a functionalized high surface

  6. Cationic mononuclear ruthenium carboxylates as catalyst prototypes for self-induced hydrogenation of carboxylic acids.

    Science.gov (United States)

    Naruto, Masayuki; Saito, Susumu

    2015-08-28

    Carboxylic acids are ubiquitous in bio-renewable and petrochemical sources of carbon. Hydrogenation of carboxylic acids to yield alcohols produces water as the only byproduct, and thus represents a possible next generation, sustainable method for the production of these alternative energy carriers/platform chemicals on a large scale. Reported herein are molecular insights into cationic mononuclear ruthenium carboxylates ([Ru(OCOR)](+)) as prototypical catalysts for the hydrogenation of carboxylic acids. The substrate-derived coordinated carboxylate was found to function initially as a proton acceptor for the heterolytic cleavage of dihydrogen, and subsequently also as an acceptor for the hydride from [Ru-H](+), which was generated in the first step (self-induced catalysis). The hydrogenation proceeded selectively and at high levels of functional group tolerance, a feature that is challenging to achieve with existing heterogeneous/homogeneous catalyst systems. These fundamental insights are expected to significantly benefit the future development of metal carboxylate-catalysed hydrogenation processes of bio-renewable resources.

  7. Biocompatibility, endocytosis, and intracellular trafficking of mesoporous silica and polystyrene nanoparticles in ovarian cancer cells: effects of size and surface charge groups

    Science.gov (United States)

    Ekkapongpisit, Maneerat; Giovia, Antonino; Follo, Carlo; Caputo, Giuseppe; Isidoro, Ciro

    2012-01-01

    Background and methods Nanoparticles engineered to carry both a chemotherapeutic drug and a sensitive imaging probe are valid tools for early detection of cancer cells and to monitor the cytotoxic effects of anticancer treatment simultaneously. Here we report on the effect of size (10–30 nm versus 50 nm), type of material (mesoporous silica versus polystyrene), and surface charge functionalization (none, amine groups, or carboxyl groups) on biocompatibility, uptake, compartmentalization, and intracellular retention of fluorescently labeled nanoparticles in cultured human ovarian cancer cells. We also investigated the involvement of caveolae in the mechanism of uptake of nanoparticles. Results We found that mesoporous silica nanoparticles entered via caveolae-mediated endocytosis and reached the lysosomes; however, while the 50 nm nanoparticles permanently resided within these organelles, the 10 nm nanoparticles soon relocated in the cytoplasm. Naked 10 nm mesoporous silica nanoparticles showed the highest and 50 nm carboxyl-modified mesoporous silica nanoparticles the lowest uptake rates, respectively. Polystyrene nanoparticle uptake also occurred via a caveolae-independent pathway, and was negatively affected by serum. The 30 nm carboxyl-modified polystyrene nanoparticles did not localize in lysosomes and were not toxic, while the 50 nm amine-modified polystyrene nanoparticles accumulated within lysosomes and eventually caused cell death. Ovarian cancer cells expressing caveolin-1 were more likely to endocytose these nanoparticles. Conclusion These data highlight the importance of considering both the physicochemical characteristics (ie, material, size and surface charge on chemical groups) of nanoparticles and the biochemical composition of the cell membrane when choosing the most suitable nanotheranostics for targeting cancer cells. PMID:22904626

  8. Preparation and reactivity of carboxylic acid-terminated boron-doped diamond electrodes

    International Nuclear Information System (INIS)

    Niedziolka-Joensson, Joanna; Boland, Susan; Leech, Donal; Boukherroub, Rabah; Szunerits, Sabine

    2010-01-01

    The paper reports on the formation of carboxy-terminated boron-doped diamond (BDD) electrodes. The carboxylic acid termination was prepared in a controlled way by reacting photochemically oxidized BDD with succinic anhydride. The resulting interface was readily employed for the linking of an amine-terminated ligand such as an osmium complex bearing an amine terminal group. The interfaces were characterized using X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). Contact angle measurements were used to follow the changes in surface wetting properties due to surface functionalization. The chemical reactivity of the carboxyl-terminated BDD was investigated by covalent coupling of the acid groups to an amine-terminated osmium complex.

  9. Synthesis of surface molecular imprinted polymers based on carboxyl-modified silica nanoparticles with the selective detection of dibutyl phthalate from tap water samples

    Science.gov (United States)

    Xu, Wanzhen; Zhang, Xiaoming; Huang, Weihong; Luan, Yu; Yang, Yanfei; Zhu, Maiyong; Yang, Wenming

    2017-12-01

    In this work, the molecular imprinted polymers were synthesized with the low monomer concentrations for dibutyl phthalate (DBP). The polymers were prepared over carboxyl-modified silica nanoparticle, which used methacrylic acid as the functional monomer, ethylene glycol dimethacrylate as the cross-linker agent and azoisobutyronitrile as the initiator in the process of preparation. Various measures were used to characterize the structure and morphology in order to get the optimal polymer. The characterization results show that the optimal polymer has suitable features for further adsorption process. And adsorption capacity experiments were evaluated to analyze its adsorption performance, through adsorption isotherms/kinetics, selectivity adsorption and desorption and regeneration experiments. These results showed that the molecular imprinted polymers had a short equilibrium time about 60 min and high stability with 88% after six cycles. Furthermore, the molecular imprinted polymers were successfully applied to remove dibutyl phthalate. The concentration range was 5.0-30.0 μmol L-1, and the limit of detection was 0.06 μmol L-1 in tap water samples.

  10. Sensitive method for dosing carboxylic functions of carbons and its application to the study of thermally processed carbon blacks

    International Nuclear Information System (INIS)

    Bernardin, Jacques

    1968-01-01

    This research thesis reports the development of a sensitive method for the dosing of carboxylic functions present at the surface of carbon blacks, and the use of this method to study the evolution of a carbon black during heat treatments. After a brief description of modes of fabrication of carbon blacks and of their structure, the author proposes an overview of knowledge on their oxidation and functional analysis. After having outlined that existing methods do not allow the measurement of function quantities less than ten micro-equivalent per gram of carbon, the author reports the development of a method which allows such measurements. By using this method, the author shows that carboxylic groups of a carbon black, oxidized by air or not, decompose during degassing by forming carbon dioxide, and that, reciprocally, the released carbon dioxide is exclusively produced by the decomposition of carboxylic groups [fr

  11. Carboxylated nitrile butadiene rubber/hybrid filler composites

    Directory of Open Access Journals (Sweden)

    Ahmad Mousa

    2012-08-01

    Full Text Available The surface properties of the OSW and NLS are measured with the dynamic contact-angle technique. The x-ray photoelectron spectroscopy (XPS of the OSW reveals that the OSW possesses various reactive functional groups namely hydroxyl groups (OH. Hybrid filler from NLS and OSW were incorporated into carboxylated nitrile rubber (XNBR to produce XNBR hybrid composites. The reaction of OH groups from the OSW with COOH of the XNBR is checked by attenuated total reflectance spectra (ATR-IR of the composites. The degree of curing ΔM (maximum torque-minimum torque as a function of hybrid filler as derived from moving die rheometer (MDR is reported. The stress-strain behavior of the hybrid composites as well as the dynamic mechanical thermal analysis (DMTA is studied. Bonding quality and dispersion of the hybrid filler with and in XNBR are examined using scanning-transmission electron microscopy (STEM in SEM.

  12. Chemo-spectroscopic sensor for carboxyl terminus overexpressed in carcinoma cell membrane.

    Science.gov (United States)

    Stanca, Sarmiza E; Matthäus, Christian; Neugebauer, Ute; Nietzsche, Sandor; Fritzsche, Wolfgang; Dellith, Jan; Heintzmann, Rainer; Weber, Karina; Deckert, Volker; Krafft, Christoph; Popp, Jürgen

    2015-10-01

    Certain carboxyl groups of the plasma membrane are involved in tumorgenesis processes. A gold core-hydroxyapatite shell (AuHA) nanocomposite is introduced as chemo-spectroscopic sensor to monitor these carboxyl groups of the cell membrane. Hydroxyapatite (HA) plays the role both of a chemical detector and of a biocompatible Raman marker. The principle of detection is based on chemical interaction between the hydroxyl groups of the HA and the carboxyl terminus of the proteins. The AuHA exhibits a surface enhanced Raman scattering (SERS) signal at 954 cm(-1) which can be used for its localization. The bio-sensing capacity of AuHA towards human skin epidermoid carcinoma (A431) and Chinese hamster ovary (CHO) cell lines is investigated using Raman microspectroscopic imaging. The localization of AuHA on cells is correlated with scanning electron microscopy, transmission electron microscopy and structured illumination fluorescence microscopy. This qualitative approach is a step towards a quantitative study of the proteins terminus. This method would enable further studies on the molecular profiling of the plasma membrane, in an attempt to provide accurate cell identification. Using a gold core-hydroxyapatite shell (AuHA) nanocomposite, the authors in this paper showed the feasibility of detecting and differentiating cell surface molecules by surface enhanced Raman scattering. Copyright © 2015 Elsevier Inc. All rights reserved.

  13. Modification of polysulfone with pendant carboxylic acid functionality ...

    Indian Academy of Sciences (India)

    polysulfone (PSF) by in situ generated chloromethyl radical in presence of stannic chloride in tetrachloroethane and .... vert the nitrile group to carboxylic acid was reported (Reddy ..... PEG molecular weight vs rejection at 35 psi pressure.

  14. Effects of Different Solvents on the Surface Acidic Oxygen-containing Functional Groups on Xanthoceras sorbifolia Shell

    Directory of Open Access Journals (Sweden)

    Linan Liu

    2014-03-01

    Full Text Available This study reports the preparation of a novel biomaterial from a forestry residue - Xanthoceras sorbifolia shell (XSS - by solvent modification. The effects of acid and base (hydrochloric acerbic, acetic acid, sodium hydroxide, ammonia water and some organic solvents (ethanol, acetone, ethyl acetate, chloroform, petroleum ether, and n-hexane on the surface acidic functional groups (SAFGs on XSS were investigated. The amount of SAFGs was quantified using acid and alkali chemical titration methods, and the characteristics of virgin XSS were compared with treated ones by FT-IR spectroscopy. It was found that acid solutions can increase the concentration of SAFGs, while alkaline solutions reduce it. The XSS treated in 0.5 M HCl has the largest number of total acidic functional groups and phenolic hydroxyl groups. The shell extracted with 2 M acetic acid has the highest concentration of carboxyl. The SAFG contents were remarkably increased by treatments with ethanol and acetone, due to the outstanding enhancement of phenolic hydroxyl. These changes in the SAFGs of XSS brought about by treatments with various solutions could be a theoretical foundation for modifying this residue to create a new type of highly efficient absorbent material.

  15. Japan Flavour and Fragrance Materials Association's (JFFMA) safety assessment of food-flavouring substances uniquely used in Japan that belong to the class of aliphatic primary alcohols, aldehydes, carboxylic acids, acetals and esters containing additional oxygenated functional groups.

    Science.gov (United States)

    Saito, Kenji; Hasegawa-Baba, Yasuko; Sekiya, Fumiko; Hayashi, Shim-Mo; Mirokuji, Yoshiharu; Okamura, Hiroyuki; Maruyama, Shinpei; Ono, Atsushi; Nakajima, Madoka; Degawa, Masakuni; Ozawa, Shogo; Shibutani, Makoto; Maitani, Tamio

    2017-09-01

    We performed a safety evaluation using the procedure devised by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) of the following four flavouring substances that belong to the class of 'aliphatic primary alcohols, aldehydes, carboxylic acids, acetals, and esters containing additional oxygenated functional groups' and are uniquely used in Japan: butyl butyrylacetate, ethyl 2-hydroxy-4-methylpentanoate, 3-hydroxyhexanoic acid and methyl hydroxyacetate. Although no genotoxicity study data were found in the published literature, none of the four substances had chemical structural alerts predicting genotoxicity. All four substances were categorised as class I by using Cramer's classification. The estimated daily intake of each of the four substances was determined to be 0.007-2.9 μg/person/day by using the maximised survey-derived intake method and based on the annual production data in Japan in 2001, 2005 and 2010, and was determined to be 0.250-600.0 μg/person/day by using the single-portion exposure technique and based on average-use levels in standard portion sizes of flavoured foods. Both of these estimated daily intake ranges were below the threshold of toxicological concern for class I substances, which is 1800 μg/person/day. Although no information from in vitro and in vivo toxicity studies for the four substances was available, these substances were judged to raise no safety concerns at the current levels of intake.

  16. Cell surface groups of two picocyanobacteria strains studied by zeta potential investigations, potentiometric titration, and infrared spectroscopy.

    Science.gov (United States)

    Dittrich, Maria; Sibler, Sabine

    2005-06-15

    In order to clarify the role of picocyanobacteria in aquatic biogeochemical processes (e.g., calcite precipitation), cell surface properties need to be investigated. An experimental study of the cell surface characteristics of two Synechococcus-type unicellular autotrophic picocyanobacterial strains was carried out. One strain was isolated from Lake Plon and contained phycocyanin, the other strain came from Lago Maggiore and was rich in phycoerythrin. Potentiometric titrations were conducted to determine the different types of sites present on the bacteria cell walls. Infrared spectroscopy allowed characterization of the various functional groups (RNH(2), RCOOH, ROH, RPO(2)) and investigations of zeta potential provided insight into the isoelectrical points of the strains. Titrations reveal three distinct sites on the bacterial surfaces of phycocyanin- and phycoerythrin-rich strains with pK values of 4.8+/-0.3/5.0+/-0.2, 6.6+/-0.2/6.7+/-0.4, and 8.8+/-0.1/8.7+/-0.2, corresponding to carboxyl, phosphate, and amine groups with surface densities of 2.6+/-0.4/7.4+/-1.6 x 10(-4), 1.9+/-0.5/4.4+/-0.8 x 10(-4), and 2.5+/-0.4/4.8+/-0.7 x 10(-4) mol/g of dry bacteria. The deprotonation constants are similar to those of bacterial strains and site densities are also within an order of magnitude of other strains. The phycoerythrin-rich strain had a higher number of binding sites than the phycocyanin-rich strain. The results showed that picocyanobacteria may adsorb either calcium cations or carbonate anions and therefore strongly influence the biogeochemical cycling of calcite in pelagic systems.

  17. Carboxylated Polyurethanes Containing Hyperbranched Polyester Soft Segments

    Directory of Open Access Journals (Sweden)

    Žigon, M.

    2006-09-01

    Full Text Available hyperbranched polyester soft segments (HB PU with functional carboxylic groups in order to enable the preparation of stable HB PU dispersions. Carboxylated hyperbranched polyurethanes were synthesized using a hyperbranched polyester based on 2,2-bis(methylolpropionic acid of the fourth pseudo-generation (Boltorn H40 and hexamethylene (HDI or isophorone diisocyanate (IPDI. The reactivity of hyperbranched polyester with HDI was lower than expected, possibly due to the presence of less reactive hydroxyl groups in the linear repeat units. A gel was formed at mole ratios rNCO/OH = 1:2 or 1:4. The synthesis of HB PU was performed with partly esterified hyperbranched polyester with lowered hydroxyl functionality. The carboxyl groups were incorporated in the HB PU backbone by reaction of residual hydroxyl groups with cis-1,2-cyclohexanedicarboxylic anhydride. HB PU aqueous dispersions were stable at least for two months, although their films were brittle. The tensile strength and Young's modulus of blends of linear and HB PU decreased with increasing content of HB PU whereas elongation at break remained nearly constant, which was explained in terms of looser chain packing due to more open tree-like hyperbranched structures.

  18. Protein kinase C activation decreases cell surface expression of the GLT-1 subtype of glutamate transporter. Requirement of a carboxyl-terminal domain and partial dependence on serine 486.

    Science.gov (United States)

    Kalandadze, Avtandil; Wu, Ying; Robinson, Michael B

    2002-11-29

    Na(+)-dependent glutamate transporters are required for the clearance of extracellular glutamate and influence both physiological and pathological effects of this excitatory amino acid. In the present study, the effects of a protein kinase C (PKC) activator on the cell surface expression and activity of the GLT-1 subtype of glutamate transporter were examined in two model systems, primary co-cultures of neurons and astrocytes that endogenously express GLT-1 and C6 glioma cells transfected with GLT-1. In both systems, activation of PKC with phorbol ester caused a decrease in GLT-1 cell surface expression. This effect is opposite to the one observed for the EAAC1 subtype of glutamate transporter (Davis, K. E., Straff, D. J., Weinstein, E. A., Bannerman, P. G., Correale, D. M., Rothstein, J. D., and Robinson, M. B. (1998) J. Neurosci. 18, 2475-2485). Several recombinant chimeric proteins between GLT-1 and EAAC1 transporter subtypes were generated to identify domains required for the subtype-specific redistribution of GLT-1. We identified a carboxyl-terminal domain consisting of 43 amino acids (amino acids 475-517) that is required for PKC-induced GLT-1 redistribution. Mutation of a non-conserved serine residue at position 486 partially attenuated but did not completely abolish the PKC-dependent redistribution of GLT-1. Although we observed a phorbol ester-dependent incorporation of (32)P into immunoprecipitable GLT-1, mutation of serine 486 did not reduce this signal. We also found that chimeras containing the first 446 amino acids of GLT-1 were not functional unless amino acids 475-517 of GLT-1 were also present. These non-functional transporters were not as efficiently expressed on the cell surface and migrated to a smaller molecular weight, suggesting that a subtype-specific interaction is required for the formation of functional transporters. These studies demonstrate a novel effect of PKC on GLT-1 activity and define a unique carboxyl-terminal domain as an

  19. Reactivity of group IV (100) semiconductor surfaces towards organic compounds

    Science.gov (United States)

    Wang, George T.

    The reactions of simple and multifunctional organic compounds with the clean silicon, germanium, and diamond (100)-2 x 1 semiconductor surfaces have been investigated using a combination of multiple internal reflection infrared spectroscopy and quantum chemistry density functional theory calculations. From these studies, an improved understanding of the atomic level reactivity of these semiconductor surfaces has been obtained, along with insights into how to achieve their selective coupling with organics of desired and varied functionality. In addition to the Si(100) and Ge(100) surfaces, our results show that cycloaddition chemistry can also be extended to the diamond (100) surface. At room temperature, 1,3-butadiene was found to form a Diels-Alder product with the diamond (100) surface, as evidenced by isotopic substitution experiments and comparison of the surface adduct with its direct molecular analogue, cyclohexene. The reactions of other classes of molecules in addition to alkenes on the Si(100) and Ge(100) surfaces, including a series of five-membered cyclic amines, were also examined. For tertiary aliphatic amines on Si(100) and both secondary and tertiary aliphatic amines on Ge(100), a majority of the molecules were observed to become stably trapped in dative-bonded precursor states rather than form energetically favorable dissociation products. For pyrrole, aromaticity was found to play a defining role in its reactivity, and a comparison of its molecular and surface reactivity reveals interesting similarities. To probe the factors controlling the selectivity of organic reactions on clean semiconductor surfaces, the adsorption of acetone and a series of unsaturated ketones was also investigated. The reaction of acetone on Ge(100) was found to be under thermodynamic control at room temperature, resulting in the formation of an "ene" product rather than the kinetically favored [2+2] C=O cycloaddition product previously observed on the Si(100) surface. In

  20. New and extended parameterization of the thermodynamic model AIOMFAC: calculation of activity coefficients for organic-inorganic mixtures containing carboxyl, hydroxyl, carbonyl, ether, ester, alkenyl, alkyl, and aromatic functional groups

    Directory of Open Access Journals (Sweden)

    A. Zuend

    2011-09-01

    Full Text Available We present a new and considerably extended parameterization of the thermodynamic activity coefficient model AIOMFAC (Aerosol Inorganic-Organic Mixtures Functional groups Activity Coefficients at room temperature. AIOMFAC combines a Pitzer-like electrolyte solution model with a UNIFAC-based group-contribution approach and explicitly accounts for interactions between organic functional groups and inorganic ions. Such interactions constitute the salt-effect, may cause liquid-liquid phase separation, and affect the gas-particle partitioning of aerosols. The previous AIOMFAC version was parameterized for alkyl and hydroxyl functional groups of alcohols and polyols. With the goal to describe a wide variety of organic compounds found in atmospheric aerosols, we extend here the parameterization of AIOMFAC to include the functional groups carboxyl, hydroxyl, ketone, aldehyde, ether, ester, alkenyl, alkyl, aromatic carbon-alcohol, and aromatic hydrocarbon. Thermodynamic equilibrium data of organic-inorganic systems from the literature are critically assessed and complemented with new measurements to establish a comprehensive database. The database is used to determine simultaneously the AIOMFAC parameters describing interactions of organic functional groups with the ions H+, Li+, Na+, K+, NH4+, Mg2+, Ca2+, Cl, Br, NO3, HSO4, and SO42−. Detailed descriptions of different types of thermodynamic data, such as vapor-liquid, solid-liquid, and liquid-liquid equilibria, and their use for the model parameterization are provided. Issues regarding deficiencies of the database, types and uncertainties of experimental data, and limitations of the model, are discussed. The challenging parameter optimization problem is solved with a novel combination of powerful global minimization

  1. Effective bounds for Brauer groups of Kummer surfaces over number fields

    DEFF Research Database (Denmark)

    Cantoral-Farfan, Victoria; Tang, Yunqing; Tanimoto, Sho

    2018-01-01

    We study effective bounds for Brauer groups of Kummer surfaces associated to the Jacobians of curves of genus 2.......We study effective bounds for Brauer groups of Kummer surfaces associated to the Jacobians of curves of genus 2....

  2. Immobilization of dendrimers on Si-C linked carboxylic acid-terminated monolayers on silicon(111)

    International Nuclear Information System (INIS)

    Boecking, Till; Wong, Elicia L.S.; James, Michael; Watson, Jolanta A.; Brown, Christopher L.; Chilcott, Terry C.; Barrow, Kevin D.; Coster, Hans G.L.

    2006-01-01

    Poly(amidoamine) dendrimers were attached to activated undecanoic acid monolayers, covalently linked to smooth silicon surfaces via Si-C bonds. The resulting ultra-thin dendrimer films were characterized by X-ray photoelectron spectroscopy (XPS), X-ray reflectometry (XR) and atomic force microscopy (AFM). XPS results suggested amide bond formation between the dendrimer and the surface carboxylic acid groups. XR yielded thicknesses of 10 A for the alkyl region of the undecanoic acid monolayer and 12 A for the dendrimer layer, considerably smaller than the diameter of these spherical macromolecules in solution. This was consistent with AFM images showing collapsed dendrimers on the surface. It was concluded that the deformation arose from a large number of amine groups on the surface of each dendrimer reacting efficiently with the activated surface, whereby the dendrimers can deform to fill voids while spreading over the activated surface to form a homogeneous macromolecular layer

  3. Surfacing the life phases of a mental health support group.

    Science.gov (United States)

    Mohr, Wanda K

    2004-01-01

    Support groups have increased rapidly in number and become a viable alternative to formal treatment in the United States. However, little is known regarding how mental health advocacy or support groups start and develop, or about challenges that can threaten their survival. In this 2 1/2-year ethnography, the author studied the culture of a developing family support program associated with a system of care. Several phases emerged, reflecting an organizational dynamic. The group dynamics and response to challenges have implications for organizers and parent organizations about the need for technical assistance necessary for survival of the group. Participant observation and immersion in the culture of such groups can provide a deeper understanding of the ideologies and values around which they organize and the kinds of tensions that members can experience during the group's cycle.

  4. Carboxyl functionalization of carbon fibers via aryl diazonium reaction in molten urea to enhance interfacial shear strength

    Science.gov (United States)

    Wang, Yuwei; Meng, Linghui; Fan, Liquan; Wu, Guangshun; Ma, Lichun; Zhao, Min; Huang, Yudong

    2016-01-01

    Using molten urea as the solvent, carbon fibers were functionalized with carboxylic acid groups via aryl diazonium reaction in 15 min to improve their interfacial bonding with epoxy resin. The surface functionalization was quantified by X-ray photoelectron spectroscopy, which showed that the relative surface coverage of carboxylic acid groups increased from an initial percentage of 3.17-10.41%. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 66%. Meanwhile, the technique did not adopt any pre-oxidation step to produce functional groups prior to grafting and was shown to maintain the tensile strength of the fibers. This methodology provided a rapid, facile and economically viable route to produce covalently functionalized carbon fibers in large quantities with an eco-friendly method.

  5. Photothermal therapy of Lewis lung carcinoma in mice using gold nanoshells on carboxylated polystyrene spheres

    Science.gov (United States)

    Liu, Huiyu; Chen, Dong; Tang, Fangqiong; Du, Gangjun; Li, Linlin; Meng, Xianwei; Liang, Wei; Zhang, Yangde; Teng, Xu; Li, Yi

    2008-11-01

    A new approach towards the design of gold nanoshells on carboxylated polystyrene spheres (GNCPSs) is reported here. Gold nanoshells were self-assembled on the surface of carboxylated polystyrene spheres by a seed growth method. Chitosan (CHI) was used as a functional agent of carboxylated polystyrene spheres for attaching gold seeds. The surface plasmon resonance (SPR) peak of GNCPSs can be tuned, greatly redshifted, over a broad spectral range including the near-infrared (NIR) wavelength region, which provides maximal penetration of light through tissue. Irradiation of GNCPSs at their peak extinction coefficient results in the conversion of light to heat energy that produces a local rise in temperature. Our study revealed that the Lewis lung carcinoma (LLC) in mice treated with GNCPSs exposed to a low dose of NIR light (808 nm, 4 W cm-2) induced irreversible tissue damage. The tumor volumes of the treatment group by GNCPSs were significantly lower than those of control groups, with an average inhibition rate over 55% (P<0.005). This study proves that GNCPSs are promising in plasmonic photothermal tumor therapy.

  6. Photothermal therapy of Lewis lung carcinoma in mice using gold nanoshells on carboxylated polystyrene spheres

    International Nuclear Information System (INIS)

    Liu Huiyu; Chen Dong; Tang Fangqiong; Li Linlin; Meng Xianwei; Li Yi; Du Gangjun; Liang Wei; Zhang Yangde; Teng Xu

    2008-01-01

    A new approach towards the design of gold nanoshells on carboxylated polystyrene spheres (GNCPSs) is reported here. Gold nanoshells were self-assembled on the surface of carboxylated polystyrene spheres by a seed growth method. Chitosan (CHI) was used as a functional agent of carboxylated polystyrene spheres for attaching gold seeds. The surface plasmon resonance (SPR) peak of GNCPSs can be tuned, greatly redshifted, over a broad spectral range including the near-infrared (NIR) wavelength region, which provides maximal penetration of light through tissue. Irradiation of GNCPSs at their peak extinction coefficient results in the conversion of light to heat energy that produces a local rise in temperature. Our study revealed that the Lewis lung carcinoma (LLC) in mice treated with GNCPSs exposed to a low dose of NIR light (808 nm, 4 W cm -2 ) induced irreversible tissue damage. The tumor volumes of the treatment group by GNCPSs were significantly lower than those of control groups, with an average inhibition rate over 55% (P<0.005). This study proves that GNCPSs are promising in plasmonic photothermal tumor therapy.

  7. Graphs of groups on surfaces interactions and models

    CERN Document Server

    White, AT

    2001-01-01

    The book, suitable as both an introductory reference and as a text book in the rapidly growing field of topological graph theory, models both maps (as in map-coloring problems) and groups by means of graph imbeddings on sufaces. Automorphism groups of both graphs and maps are studied. In addition connections are made to other areas of mathematics, such as hypergraphs, block designs, finite geometries, and finite fields. There are chapters on the emerging subfields of enumerative topological graph theory and random topological graph theory, as well as a chapter on the composition of English

  8. Homologie cyclique du produit croise algebrique et groupes de surfaces

    NARCIS (Netherlands)

    Bella Baci, A.

    1997-01-01

    Let a group G act on an associative algebra A One can form the algebraic crossed product A G cf which plays the role of a noncommutative quotient in Conness theory The cyclic homology of this algebra was studied extensively in a series of papers It is well known that this homology admits a

  9. Sunspot Groups as Tracers of Sub Surface Processes .

    Indian Academy of Sciences (India)

    tribpo

    Owing to shortage of time I restrict this review to present a report on the work done by our group at Indian Institute of Astrophysics which fits the title of this colloquium and the title of my talk. I shall point out the clues given by these studies for modeling the cyclical evolution of solar magnetic fields, but I shall not report on the ...

  10. Group IV nanocrystals with ion-exchangeable surface ligands and methods of making the same

    Science.gov (United States)

    Wheeler, Lance M.; Nichols, Asa W.; Chernomordik, Boris D.; Anderson, Nicholas C.; Beard, Matthew C.; Neale, Nathan R.

    2018-01-09

    Methods are described that include reacting a starting nanocrystal that includes a starting nanocrystal core and a covalently bound surface species to create an ion-exchangeable (IE) nanocrystal that includes a surface charge and a first ion-exchangeable (IE) surface ligand ionically bound to the surface charge, where the starting nanocrystal core includes a group IV element.

  11. Surface Curvature in Island Groups and Discontinuous Cratonic Structures

    Science.gov (United States)

    McDowell, M. S.

    2002-05-01

    The Canadian Archipelago includes eight major islands and a host of smaller ones. They are separated by water bodies, of varying widths attributable to glacial activity and ocean currents. Land form varies from relatively rugged mountains (~2000 m) in eastern, glacial, islands, to low lying western, similar to the continental topography adjacent. The Arctic region is thought to have been low average elevation before the Pleistocene. To a picture puzzler, it all looks like it fit together. Experimentally cutting apart the islands from large scale maps shows that the rough edges match fairly well. However, when those independent pieces are sutured together, without restraint, as in free air, the fit is far better. Far more importantly, they consistently form a noticeably concave surface. This tendency is not at all apparent in flat surface or computer screen manipulation; the pieces need to be "hand joined" or on a molded surface to allow the assembly to freely form as it will. Fitting together the coastlines above 60 \\deg north, from 120 \\deg west to 45 \\deg east, and comparing the resulting contracted area to the original, obtains an 8 percent area reduction. The curvature "humps" a trial planar section of 15 cms by 1.6 cm, a substantial difference in the radius of curvature. If you rashly suggest applying that formula globally, the resulting sphere would have a surface area of 4.7 x108,(down from 5 x108), and therefore radius of 6117 km, down from 6400, which is a rather preposterous conclusion. As nobody would believe it, I tested the idea elsewhere. The Huronian succession of six named cratons is adjacent on the south. I cut this map apart, too, and fit it together, once again getting a curvature, this time more pronounced. I am trying it with the Indonesian Archipelago, although this area has volcanic complications, and with Precambrian Basins in western Australia and Nimibia, Africa. Indications are - an essentially similar pattern of fit, but non uniform

  12. Application of Nanotrap technology for high sensitivity measurement of urinary outer surface protein A carboxyl-terminus domain in early stage Lyme borreliosis.

    Science.gov (United States)

    Magni, Ruben; Espina, Benjamin H; Shah, Ketul; Lepene, Benjamin; Mayuga, Christine; Douglas, Temple A; Espina, Virginia; Rucker, Sally; Dunlap, Ross; Petricoin, Emanuel F Iii; Kilavos, Mary Frekko; Poretz, Donald M; Irwin, Gilbert R; Shor, Samuel M; Liotta, Lance A; Luchini, Alessandra

    2015-11-04

    Prompt antibiotic treatment of early stage Lyme borreliosis (LB) prevents progression to severe multisystem disease. There is a clinical need to improve the diagnostic specificity of early stage Lyme assays in the period prior to the mounting of a robust serology response. Using a novel analyte harvesting nanotechnology, Nanotrap particles, we evaluated urinary Borrelia Outer surface protein A (OspA) C-terminus peptide in early stage LB before and after treatment, and in patients suspected of late stage disseminated LB. We employed Nanotrap particles to concentrate urinary OspA and used a highly specific anti-OspA monoclonal antibody (mAb) as a detector of the C-terminus peptides. We mapped the mAb epitope to a narrow specific OspA C-terminal domain OspA236-239 conserved across infectious Borrelia species but with no homology to human proteins and no cross-reactivity with relevant viral and non-Borrelia bacterial proteins. 268 urine samples from patients being evaluated for all categories of LB were collected in a LB endemic area. The urinary OspA assay, blinded to outcome, utilized Nanotrap particle pre-processing, western blotting to evaluate the OspA molecular size, and OspA peptide competition for confirmation. OspA test characteristics: sensitivity 1.7 pg/mL (lowest limit of detection), % coefficient of variation (CV) = 8 %, dynamic range 1.7-30 pg/mL. Pre-treatment, 24/24 newly diagnosed patients with an erythema migrans (EM) rash were positive for urinary OspA while false positives for asymptomatic patients were 0/117 (Chi squared p antibiotic therapy, 10/10 were positive for urinary OspA. Urinary OspA of 8/8 patients switched from detectable to undetectable following symptom resolution post-treatment. Specificity of the urinary OspA test for the clinical symptoms was 40/40. Specificity of the urinary OspA antigen test for later serology outcome was 87.5 % (21 urinary OspA positive/24 serology positive, Chi squared p = 4.072e(-15)). 41 of 100 patients under

  13. Biocompatibility, endocytosis, and intracellular trafficking of mesoporous silica and polystyrene nanoparticles in ovarian cancer cells: effects of size and surface charge groups

    Directory of Open Access Journals (Sweden)

    Ekkapongpisit M

    2012-07-01

    Full Text Available Maneerat Ekkapongpisit,1 Antonino Giovia,1 Carlo Follo,1 Giuseppe Caputo,2,3 Ciro Isidoro11Laboratory of Molecular Pathology and Nanobioimaging, Department of Health Sciences, Università del Piemonte Orientale “A Avogadro”, Novara, 2Dipartimento di Chimica dell’Università di Torino, Torino, 3Cyanine Technology SpA, Torino, ItalyBackground and methods: Nanoparticles engineered to carry both a chemotherapeutic drug and a sensitive imaging probe are valid tools for early detection of cancer cells and to monitor the cytotoxic effects of anticancer treatment simultaneously. Here we report on the effect of size (10–30 nm versus 50 nm, type of material (mesoporous silica versus polystyrene, and surface charge functionalization (none, amine groups, or carboxyl groups on biocompatibility, uptake, compartmentalization, and intracellular retention of fluorescently labeled nanoparticles in cultured human ovarian cancer cells. We also investigated the involvement of caveolae in the mechanism of uptake of nanoparticles.Results: We found that mesoporous silica nanoparticles entered via caveolae-mediated endocytosis and reached the lysosomes; however, while the 50 nm nanoparticles permanently resided within these organelles, the 10 nm nanoparticles soon relocated in the cytoplasm. Naked 10 nm mesoporous silica nanoparticles showed the highest and 50 nm carboxyl-modified mesoporous silica nanoparticles the lowest uptake rates, respectively. Polystyrene nanoparticle uptake also occurred via a caveolae-independent pathway, and was negatively affected by serum. The 30 nm carboxyl-modified polystyrene nanoparticles did not localize in lysosomes and were not toxic, while the 50 nm amine-modified polystyrene nanoparticles accumulated within lysosomes and eventually caused cell death. Ovarian cancer cells expressing caveolin-1 were more likely to endocytose these nanoparticles.Conclusion: These data highlight the importance of considering both the

  14. Tailoring surface groups of carbon quantum dots to improve photoluminescence behaviors

    International Nuclear Information System (INIS)

    Tian, Ruixue; Hu, Shengliang; Wu, Lingling; Chang, Qing; Yang, Jinlong; Liu, Jun

    2014-01-01

    Highlights: • We develop a facile and green method to tailor surface groups. • Photoluminescence behaviors of carbon quantum dots are improved by tailoring their surface groups. • Highly luminescent efficiency is produced by amino-hydrothermal treatment of reduced carbon quantum dots. - Abstract: A facile and green method to tailor surface groups of carbon quantum dots (CQDs) is developed by hydrothermal treatment in an autoclave. The photoluminescence (PL) behaviors of CQDs depend on the types of surface groups. Highly efficient photoluminescence is obtained through amino-hydrothermal treatment of the CQDs reduced by NaBH 4 . The effects of surface groups on PL behavior are attributed to the degrees of energy band bending induced by surface groups

  15. Catalytic oxidation of 1,2-DCBz over V2O5/TiO2-CNTs: effect of CNT diameter and surface functional groups.

    Science.gov (United States)

    Du, Cuicui; Wang, Qiulin; Peng, Yaqi; Lu, Shengyong; Ji, Longjie; Ni, Mingjiang

    2017-02-01

    A series of V 2 O 5 /TiO 2 -carbon nanotube (CNT) catalysts were prepared and tested to decompose gaseous 1,2-dichlorobenzene (1,2-DCBz). Several physicochemical methods, including nitrogen adsorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and H 2 temperature-programmed reduction (TPR) were employed to characterise their physicochemical properties. To better understand the effect of CNT properties on the reactivity of V 2 O 5 /TiO 2 -CNT catalysts, the 1,2-DCBz residue remaining in the off-gas and on the catalyst surface were both collected and analysed. The results indicate that the outer diameter and the surface functional groups (hydroxide radical and carboxyl) of CNTs significantly influence upon the catalytic activity of CNT-containing V 2 O 5 /TiO 2 catalysts: the CNT outer diameter mainly affects the aggregation of CNTs and the π-π interaction between the benzene ring and CNTs, while the introduction of -OH and -COOH groups by acid treatment can further enlarge specific surface area (SSA) and contribute to a higher average oxidation state of vanadium (V aos ) and supplemental surface chemisorbed oxygen (O ads ). In addition, the enhanced mobility of lattice oxygen (O latt) also improves the oxidation ability of the catalysts.

  16. The mechanism of mediated oxidation of carboxylates with ferrocene as redox catalyst in absence of grafting effects. An experimental and theoretical approach

    International Nuclear Information System (INIS)

    Hernández-Muñoz, Lindsay S.; Galano, Annia; Astudillo-Sánchez, Pablo D.; Abu-Omar, Mahdi M.; González, Felipe J.

    2014-01-01

    Graphical abstract: - Highlights: • The mechanism of mediated oxidation of carboxylates. • Thermodynamics of the mediated Kolbe and Non-Kolbe mechanisms. • The oxidation of acetate and diphenylacetate ions by using ferrocene as redox catalyst. • Simulation and DFT calculations of the mediated oxidation of carboxylates. • Radical and carbocationic pathways in the carboxylate oxidation in acetonitrile. - Abstract: The oxidation of tetrabutylammonium carboxylates by using ferrocene derivatives as redox mediators has been recently used to perform the covalent grafting of carbon surfaces with organic and organometallic groups. Due to the intervention of this surface process, a partial description of the reaction mechanism has only been stated. Therefore, this article concerns about two features of the oxidation of carboxylates mediated by ferrocene. In the first part, it is discussed that in the oxidation of acetate ions by using ferrocene as redox catalyst, the gap between both oxidation potentials is very high, which means that the homogeneous electron transfer between the acetate ion and the electrochemically generated ferrocenium ion is energetically unfavorable. However, by using density functional theory calculations, it has been shown that the whole set of coupled chemical reactions involved either in a Kolbe or Non-Kolbe pathway drive the overall mechanisms towards a thermodynamically favorable situation. In order to avoid the strong covalent grafting process that occurs during the mediated oxidation of acetate ions, the second part of this work deals with the oxidation of tetrabutylammonium diphenylacetate by using ferrocene as a redox mediator in acetonitrile on glassy carbon electrodes. With this carboxylate, no electrode inhibition process occurs and, therefore cyclic voltammetry simulation was done to propose the electrochemical and chemical steps that are present when a carboxylate oxidation is performed in the presence of ferrocene derivatives

  17. Nano-graphene oxide carboxylation for efficient bioconjugation applications: a quantitative optimization approach

    Energy Technology Data Exchange (ETDEWEB)

    Imani, Rana; Emami, Shahriar Hojjati, E-mail: semami@aut.ac.ir [Amirkabir University of Technology, Department of Biomedical Engineering (Iran, Islamic Republic of); Faghihi, Shahab, E-mail: shahabeddin.faghihi@mail.mcgill.ca, E-mail: sfaghihi@nigeb.ac.ir [National Institute of Genetic Engineering and Biotechnology, Tissue Engineering and Biomaterials Division (Iran, Islamic Republic of)

    2015-02-15

    A method for carboxylation of graphene oxide (GO) with chloroacetic acid that precisely optimizes and controls the efficacy of the process for bioconjugation applications is proposed. Quantification of COOH groups on nano-graphene oxide sheets (NGOS) is performed by novel colorimetric methylene blue (MB) assay. The GO is synthesized and carboxylated by chloroacetic acid treatment under strong basic condition. The size and morphology of the as-prepared NGOS are characterized by scanning electron microscopy, transmission electron microscopy (TEM), and atomic force microscopy (AFM). The effect of acid to base molar ratio on the physical, chemical, and morphological properties of NGOS is analyzed by Fourier-transformed infrared spectrometry (FTIR), UV–Vis spectroscopy, X-ray diffraction (XRD), AFM, and zeta potential. For evaluation of bioconjugation efficacy, the synthesized nano-carriers with different carboxylation ratios are functionalized by octaarginine peptide sequence (R8) as a biomolecule model containing amine groups. The quantification of attached R8 peptides to graphene nano-sheets’ surface is performed with a colorimetric-based assay which includes the application of 2,4,6-Trinitrobenzene sulfonic acid (TNBS). The results show that the thickness and lateral size of nano-sheets are dramatically decreased to 0.8 nm and 50–100 nm after carboxylation process, respectively. X-ray analysis shows the nano-sheets interlaying space is affected by the alteration of chloroacetic acid to base ratio. The MB assay reveals that the COOH groups on the surface of NGOS are maximized at the acid to base ratio of 2 which is confirmed by FTIR, XRD, and zeta potential. The TNBS assay also shows that bioconjugation of the optimized carboxylated NGOS sample with octaarginine peptide is 2.5 times more efficient compared to bare NGOS. The present work provides evidence that treatment of GO by chloroacetic acid under an optimized condition would create a functionalized high

  18. Nano-graphene oxide carboxylation for efficient bioconjugation applications: a quantitative optimization approach

    International Nuclear Information System (INIS)

    Imani, Rana; Emami, Shahriar Hojjati; Faghihi, Shahab

    2015-01-01

    A method for carboxylation of graphene oxide (GO) with chloroacetic acid that precisely optimizes and controls the efficacy of the process for bioconjugation applications is proposed. Quantification of COOH groups on nano-graphene oxide sheets (NGOS) is performed by novel colorimetric methylene blue (MB) assay. The GO is synthesized and carboxylated by chloroacetic acid treatment under strong basic condition. The size and morphology of the as-prepared NGOS are characterized by scanning electron microscopy, transmission electron microscopy (TEM), and atomic force microscopy (AFM). The effect of acid to base molar ratio on the physical, chemical, and morphological properties of NGOS is analyzed by Fourier-transformed infrared spectrometry (FTIR), UV–Vis spectroscopy, X-ray diffraction (XRD), AFM, and zeta potential. For evaluation of bioconjugation efficacy, the synthesized nano-carriers with different carboxylation ratios are functionalized by octaarginine peptide sequence (R8) as a biomolecule model containing amine groups. The quantification of attached R8 peptides to graphene nano-sheets’ surface is performed with a colorimetric-based assay which includes the application of 2,4,6-Trinitrobenzene sulfonic acid (TNBS). The results show that the thickness and lateral size of nano-sheets are dramatically decreased to 0.8 nm and 50–100 nm after carboxylation process, respectively. X-ray analysis shows the nano-sheets interlaying space is affected by the alteration of chloroacetic acid to base ratio. The MB assay reveals that the COOH groups on the surface of NGOS are maximized at the acid to base ratio of 2 which is confirmed by FTIR, XRD, and zeta potential. The TNBS assay also shows that bioconjugation of the optimized carboxylated NGOS sample with octaarginine peptide is 2.5 times more efficient compared to bare NGOS. The present work provides evidence that treatment of GO by chloroacetic acid under an optimized condition would create a functionalized high

  19. Carboxyl functionalized carbon fibers with preserved tensile strength and electrochemical performance used as anodes of structural lithium-ion batteries

    International Nuclear Information System (INIS)

    Feng, Mengjie; Wang, Shubin; Yu, Yalin; Feng, Qihang; Yang, Jiping; Zhang, Boming

    2017-01-01

    Highlights: • Carboxyl functionalized CF is acquired by simple chemical oxidation method. • These CF have preserved the tensile strength, better electrochemical properties. • The presence of H_3PO_4 prevented the turbostratic carbon from over-oxidization. • There CF can be used as anodes of multifunctional structural battery. • The preservation and improvement is result from the hindered over-oxidization. - Abstract: Carboxyl functionalized carbon fibers with preserved tensile strength and electrochemical properties were acquired through a simple chemical oxidation method, and the proposed underlying mechanism was verified. The surface of carboxyl functionalizing carbon fibers is necessary in acquiring functional groups on the surface of carbon fibers to further improve the thermal, electrical or mechanical properties of the fibers. Functionalization should preserve the tensile strength and electrochemical properties of carbon fibers, because the anodes of structural batteries need to have high strength and electrochemical properties. Functionalized with mixed H_2SO_4/HNO_3 considerably reduced the tensile strength of carbon fibers. By contrast, the appearance of H_3PO_4 preserved the tensile strength of functionalized carbon fibers, reduced the dispersion level of tensile strength values, and effectively increased the concentration of functional acid groups on the surface of carbon fibers. The presence of phosphoric acid hindered the over-oxidation of turbostratic carbon, and consequently preserved the tensile strength of carbon fibers. The increased proportion of turbostratic carbon on the surface of carbon fibers concurrently enhanced the electrochemical properties of carbon fibers.

  20. Carboxylic acid functionalization of halloysite nanotubes for sustained release of diphenhydramine hydrochloride

    Energy Technology Data Exchange (ETDEWEB)

    Zargarian, S. Sh.; Haddadi-Asl, V., E-mail: haddadi@aut.ac.ir; Hematpour, H. [Amirkabir University of Technology, Department of Polymer Engineering and Color Technology (Iran, Islamic Republic of)

    2015-05-15

    Halloysite nanotubes (HNT) (cylindrical shape with external diameter and length in the range of 30–80 nm and 0.2–1 µm, respectively) were functionalized with 3-aminopropyltriethoxysilane (APTES) from hydroxyl groups by a coupling reaction. Subsequently, maleic anhydride was attached to the APTES moieties to yield carboxylic acid-functionalized HNT. Loading and subsequent release of a model drug molecule diphenhydramine hydrochloride (DPH) on modified and unmodified nanotubes were investigated. Morphology of HNT was studied by electron microscopy. Successful attachment of APTES and carboxylic acid groups to halloysite and drug loading were evaluated by Fourier transform infrared spectroscopy. The amount of surface modification and drug adsorption capacity were calculated via thermogravimetric analysis. The ordered crystal structure of loaded drug was evaluated by X-ray diffraction. UV–Visible spectrophotometer was used to study drug release from modified and unmodified samples. Carboxylated halloysite exhibits higher loading capacity and prolonged release of DPH as compared to that of the natural halloysite.

  1. Carboxylic acid functionalization of halloysite nanotubes for sustained release of diphenhydramine hydrochloride

    International Nuclear Information System (INIS)

    Zargarian, S. Sh.; Haddadi-Asl, V.; Hematpour, H.

    2015-01-01

    Halloysite nanotubes (HNT) (cylindrical shape with external diameter and length in the range of 30–80 nm and 0.2–1 µm, respectively) were functionalized with 3-aminopropyltriethoxysilane (APTES) from hydroxyl groups by a coupling reaction. Subsequently, maleic anhydride was attached to the APTES moieties to yield carboxylic acid-functionalized HNT. Loading and subsequent release of a model drug molecule diphenhydramine hydrochloride (DPH) on modified and unmodified nanotubes were investigated. Morphology of HNT was studied by electron microscopy. Successful attachment of APTES and carboxylic acid groups to halloysite and drug loading were evaluated by Fourier transform infrared spectroscopy. The amount of surface modification and drug adsorption capacity were calculated via thermogravimetric analysis. The ordered crystal structure of loaded drug was evaluated by X-ray diffraction. UV–Visible spectrophotometer was used to study drug release from modified and unmodified samples. Carboxylated halloysite exhibits higher loading capacity and prolonged release of DPH as compared to that of the natural halloysite

  2. Decellularized Bovine Articular Cartilage Matrix Reinforced by Carboxylated-SWCNT for Tissue Engineering Application

    Directory of Open Access Journals (Sweden)

    Zari Majidi Mohammadie

    2018-01-01

    Full Text Available ABSTRACT Nanotubes with their unique properties have diversified mechanical and biological applications. Due to similarity of dimensions with extracellular matrix (ECM elements, these materials are used in designing scaffolds. In this research, Carboxylated Single-Wall Carbon Nanotubes in optimization of decellularized scaffold of bovine articular cartilage was used. At first, the articular cartilage was decellularized. Then the scaffolds were analyzed in: (i decellularized scaffolds, and (ii scaffolds plunged into homogenous suspension of nanotubes in distilled water, were smeared with Carboxylated-SWCNT. The tissue rings derived from the rabbit's ear were assembled with reinforced scaffolds and they were placed in a culture media for 15 days. The scaffolds in two groups and the assembled scaffolds underwent histologic and electron microscopy. Scanning electron microscopy showed that the structure of ECM of articular cartilage has been maintained well after decellularization. Fourier transform infrared analysis showed that the contents of ECM have not been changed under treatment process. Atomic force microscopy analysis showed the difference in surface topography and roughness of group (ii scaffolds in comparison with group (i. Transmission electron microscopy studies showed the Carboxylated-SWCNT bond with the surface of decellularized scaffold and no penetration of these compounds into the scaffold. The porosity percentage with median rate of 91.04 in group (i scaffolds did not have significant difference with group (ii scaffolds. The electron microscopy observations confirmed migration and penetration of the blastema cells into the group (ii assembled scaffolds. This research presents a technique for provision of nanocomposite scaffolds for cartilage engineering applications.

  3. Methyl (Sp-2-(diphenylphosphinoferrocene-1-carboxylate

    Directory of Open Access Journals (Sweden)

    Petr Štěpnička

    2009-10-01

    Full Text Available The title compound, [Fe(C5H5(C19H16O2P], obtained serendipitously during recrystallization of 1-hydroxybenzotriazolyl (Sp-2-(diphenylphosphinoferrocene-1-carboxylate from methanol, crystallizes in the chiral space group P212121. Its crystal structure not only confirms the anticipated absolute configuration but also establishes a rather regular geometry for the ferrocene unit, devoid of any significant deformation due to the attached substituents. In the crystal, symmetry-related molecules are linked via weak C—H...O interactions.

  4. Grafting of phosphorylcholine functional groups on polycarbonate urethane surface for resisting platelet adhesion

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Bin [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Feng, Yakai, E-mail: yakaifeng@hotmail.com [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China); Key Laboratory of Systems Bioengineering, Ministry of Education, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Lu, Jian; Zhang, Li; Zhao, Miao; Shi, Changcan; Khan, Musammir [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Guo, Jintang [School of Chemical Engineering and Technology, Tianjin University, Weijin Road 92, Tianjin 300072 (China); Tianjin University-Helmholtz-Zentrum Geesthacht, Joint Laboratory for Biomaterials and Regenerative Medicine, Weijin Road 92, 300072 Tianjin (China)

    2013-07-01

    In order to improve the resistance of platelet adhesion on material surface, 2-methacryloyloxyethyl phosphorylcholine (MPC) was grafted onto polycarbonate urethane (PCU) surface via Michael reaction to create biomimetic structure. After introducing primary amine groups via coupling tris(2-aminoethyl)amine (TAEA) onto the polymer surface, the double bond of MPC reacted with the amino group to obtain MPC modified PCU. The modified surface was characterized by Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectroscopy (XPS). The results verified that MPC was grafted onto PCU surface by Michael reaction method. The MPC grafted PCU surface had a low water contact angle and a high water uptake. This means that the hydrophilic PC functional groups improved the surface hydrophilicity significantly. In addition, surface morphology of MPC grafted PCU film was imaged by atomic force microscope (AFM). The results showed that the grafted surface was rougher than the blank PCU surface. In addition, platelet adhesion study was evaluated by scanning electron microscopy (SEM) observation. The PCU films after treated with platelet-rich plasma demonstrated that much fewer platelets adhered to the MPC-grafted PCU surface than to the blank PCU surface. The antithrombogenicity of the MPC-grafted PCU surface was determined by the activated partial thromboplastin time (APTT). The result suggested that the MPC modified PCU may have potential application as biomaterials in blood-contacting and some subcutaneously implanted devices. - Highlights: • MPC was successfully grafted onto polycarbonate urethane surface via Michael reaction. • High concentration of PC functional groups on the surface via TAEA molecule • Biomimetic surface modification • The modified surface showed high hydrophilicity and anti-platelet adhesion.

  5. Surface functional group characterization using chemical derivatization X-ray photoelectron spectroscopy (CD-XPS)

    Energy Technology Data Exchange (ETDEWEB)

    Jagst, Eda

    2011-03-18

    Chemical derivatization - X-ray photolectron spectroscopy (CD-XPS) was applied successfully in order to determine different functional groups on thin film surfaces. Different amino group carrying surfaces, prepared by spin coating, self-assembly and plasma polymerization, were successfully investigated by (XPS) and near edge X-ray absorption fine structure (NEXAFS) spectroscopy. Amino groups were derivatized with the widely used primary amino group tags, pentafluorobenzaldehyde (PFB) and 4-(trifluoromethyl)-benzaldehyde (TFBA), prior to analysis. Primary amino group quantification was then carried out according to the spectroscopical data. Self-assembled monolayers (SAMs) of different terminal groups were prepared and investigated with XPS and spectra were compared with reference surfaces. An angle resolved NEXAFS measurement was applied to determine the orientation of SAMs. Plasma polymerized allylamine samples with different duty cycle, power and pressure values were prepared in order to study the effects of external plasma parameters on the primary amino group retention. CD-XPS was used to quantify the amino groups and experiments show, that the milder plasma conditions promote the retention of amino groups originating from the allylamine monomer. An interlaboratory comparison of OH group determination on plasma surfaces of polypropylene treated with oxygen plasma, was studied. The surfaces were investigated with XPS and the [OH] amount on the surfaces was calculated. (orig.)

  6. In situ SERS and X-ray photoelectron spectroscopy studies on the pH-dependant adsorption of anthraquinone-2-carboxylic acid on silver electrode

    Energy Technology Data Exchange (ETDEWEB)

    Li, Dan, E-mail: dany@sit.edu.cn [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Jia, Shaojie [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Fodjo, Essy Kouadio [Laboratory of Physical Chemistry, University Felix Houphouet Boigny, 22 BP 582, Abidjan 22, Cote d’Ivoire (Cote d' Ivoire); Xu, Hu [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Wang, Yuhong, E-mail: yuhong_wang502@sit.edu.cn [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China); Deng, Wei [School of Chemical and Environmental Engineering, Shanghai Institute of Technology, 100 Haiquan Road, Shanghai 201418 (China)

    2016-03-30

    Graphical abstract: The orientation of anthraquinone-2-carboxylic acid (AQ-2-COOH) has been investigated by in situ surface-enhanced Raman scattering (in situ SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) on silver surface. - Highlights: • The adsorption behavior of anthraquinone-2-carboxylic acid (AQ-2-COOH) on Ag electrode is influenced by the pH. • The pH-dependant adsorption of AQ-2-COOH has been confirmed by in situ surface-enhanced Raman scattering (in situ SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS). • The results can provide insights into electron transfer reactions of AQ-2-COOH in biological systems. - Abstract: In this study, in situ surface-enhanced Raman scattering (SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) are used to investigate the redox reaction and adsorption behavior of anthraquinone-2-carboxylic acid (AQ-2-COOH) on an Ag electrode at different pH values. The obtained results indicate that AQ-2-COOH is adsorbed tilted on the Ag electrode through O-atom of ring carbonyl in a potential range from −0.3 to −0.5 V vs. SCE, but the orientation turns to more tilted orientation with both O-atom of the ring carbonyl and carboxylate group in positive potential region for pH 6.0 and 7.4. However, at pH 10.0, the orientation adopts tilted conformation constantly on the Ag electrode with both O-atom of the anthraquinone ring and carboxylate group in the potential range from −0.3 to −0.5 V vs. SCE or at positive potentials. Moreover, the adsorption behavior of AQ-2-COOH has been further confirmed by AR-XPS on the Ag surface. Proposed reasons for the observed changes in orientation are presented.

  7. Cure and mechanical properties of carboxylated nitrile rubber (XNBR) vulcanized by alkaline earth metal compounds

    Science.gov (United States)

    Tulyapitak, Tulyapong

    Compounds of carboxylated nitrile rubber (XNBR) with alkaline metal oxides and hydroxide were prepared, and their cure and mechanical properties were investigated. Magnesium oxide (MgO) with different specific surface areas (45, 65, and 140 m2/g) was used. Increased specific surface area and concentration of MgO resulted in higher cure rate. Optimum stiffness, tensile strength, and ultimate strain required an equimolar amount of acidity and MgO. The effect of specific surface area on tensile properties was not significant. Crosslink density of XNBR-MgO vulcanizates increased with increased amounts of MgO. ATR-IR spectroscopy showed that neutralization occurs in two steps: (1) During mixing and storage, MgO reacts with carboxyl groups (RCOOH) to give RCOOMgOH. (2) Upon curing, these react bimolecularly to form RCOOMgOOCR and Mg(OH)2. Dynamic mechanical thermal analysis revealed an ionic transition at higher temperature, in addition to the glass transition. The ionic transition shifts to higher temperature with increasing MgO concentration. Like MgO-XNBR systems, cure rates of XNBR-calcium hydroxide (Ca(OH)2) and XNBR-barium oxide (BaO) compounds increased with increased content of curing agents. Curing by these two agents resulted in ionic crosslinks. To ensure optimum tensile properties, equimolar amounts of carboxyl groups and curing agents were required. Dynamic mechanical analysis revealed the ionic transition in these two systems. It shifted to higher temperature with increased amounts of curing agents. In contrast to MgO, Ca(OH)2, and BaO, calcium oxide (CaO) gave results similar to those for thermally cured samples. No ionic transition was observed in XNBR-CaO systems. Tensile strength of XNBR depended on the strength of ionic crosslinks, which was dependent on the size of the alkaline metal ions.

  8. The multilevel analysis of surface acting and mental health: A moderation of positive group affective tone

    Science.gov (United States)

    Lee, Meng-Shiu; Huang, Jui-Chan; Wu, Tzu-Jung

    2017-06-01

    The purpose of this study is to investigate the relationship among surface acting, mental health, and positive group affective tone. According to the prior theory, this study attempts to establish a comprehensive research framework among these variables, and furthermore tests the moderating effect of positive group affective tone. Data were collected from 435 employees in 52 service industrial companies by questionnaire, and this study conducted multilevel analysis. The results showed that surface acting will negatively affect the mental health. In addition, the positive group affective tone have significant moderating effect on the relationship among surface acting and mental health. Finally, this study discusses managerial implications and highlights future research suggestions.

  9. Overview on the Surface Functionalization Mechanism and Determination of Surface Functional Groups of Plasma Treated Carbon Nanotubes.

    Science.gov (United States)

    Saka, Cafer

    2018-01-02

    The use of carbon materials for many applications is due to the unique diversity of structures and properties ranging from chemical bonds between the carbon atoms of the materials to nanostructures, crystallite alignment, and microstructures. Carbon nanotubes and other nanoscale carbonaceous materials draw much attention due to their physical and chemical properties, such as high strength, high resistance to corrosion, electrical and thermal conductivity, stability and a qualified adsorbent. Carbon-based nanomaterials, which have a relatively large specific area and layered structure, can be used as an adsorbent for efficient removal of organic and inorganic contaminants. However, one of the biggest obstacles to the development of carbon-based nanomaterials adsorbents is insolubility and the lack of functional groups on the surface. There are several approaches to introduce functional groups on carbon nanotubes. One of these approaches, plasma applications, now has an important place in the creation of surface functional groups as a flexible, fast, and environmentally friendly method. This review focuses on recent information concerning the surface functionalization and modification of plasma treated carbon nanotube. This review considers the surface properties, advantages, and disadvantages of plasma-applied carbon nanotubes. It also examines the reaction mechanisms involved in the functional groups on the surface.

  10. Theoretical study on the interactions between chlordecone hydrate and acidic surface groups of activated carbon under basic pH conditions.

    Science.gov (United States)

    Melchor-Rodríguez, Kenia; Gamboa-Carballo, Juan José; Ferino-Pérez, Anthuan; Passé-Coutrin, Nady; Gaspard, Sarra; Jáuregui-Haza, Ulises Javier

    2018-05-01

    A theoretical study of the influence of acidic surface groups (SG) of activated carbon (AC) on chlordecone hydrate (CLDh) adsorption is presented, in order to help understanding the adsorption process under basic pH conditions. A seven rings aromatic system (coronene) with a functional group in the edge was used as a simplified model of AC to evaluate the influence of SG in the course of adsorption from aqueous solution at basic pH conditions. Two SG were modeled in their deprotonated form: carboxyl and hydroxyl (COO - and O - ), interacting with CLDh. In order to model the solvation process, all systems under study were calculated with up to three water molecules. Multiple Minima Hypersurface (MMH) methodology was employed to study the interactions of CLDh with SG on AC using PM7 semiempirical Hamiltonian, to explore the potential energy surfaces of the systems and evaluate their thermodynamic association energies. The re-optimization of representative structures obtained from MMH was done using M06-2X Density Functional Theory. The Quantum Theory of Atoms in Molecules (QTAIM) was used to characterize the interaction types. As result, the association of CLDh with acidic SG at basic pH conditions preferentially occurs between the two alcohol groups of CLDh with COO - and O - groups and by dispersive interactions of chlorine atoms of CLDh with the graphitic surface. On the other hand, the presence of covalent interactions between the negatively charged oxygen of SG and one hydrogen atom of CLDh alcohol groups (O - ⋯HO interactions) without water molecules, was confirmed by QTAIM study. It can be concluded that the interactions of CLDh with acidic SG of AC under basic pH conditions confirms the physical mechanisms of adsorption process. Copyright © 2018 Elsevier Inc. All rights reserved.

  11. Synthesis and study of dioxouranium (6) carboxylate complexes with ammonia

    International Nuclear Information System (INIS)

    Spitsyn, V.I.; Mazo, G.N.; Dunaev, K.M.; Santalova, N.A.

    1980-01-01

    Heterophase synthesis of a series of ammonia complexes of dioxouranium (6) carboxylates namely, UO 2 (HCOO) 2 x2NH 3 , UO 2 (CH 3 COO) 2 x2NH 3 , UO 2 (CH 3 CH 2 OO) 2 x2NH 3 is presented and their properties and structure are studied. Comparison of infrared spectra of dioxouranium (6) carboxylates and their ammonia complexes has shown that NH 3 molecule introduction changes in principle the coordination of azidoligand turning out bridge carboxylate groups into island ones and weakening their bonds with central cations. In spectra of all diammiacates the shift of bands of deformational and valent oscillations of N-H bond in comparison with spectrum of pure ammonia tells about NH 3 coordination with metal. Complexes thermolysis has been studied under iso- and polythermal conditions. General diagram of thermal decay is presented [ru

  12. Atom-Economical Dimerization Strategy by the Rhodium-Catalyzed Addition of Carboxylic Acids to Allenes: Protecting-Group-Free Synthesis of Clavosolide A and Late-Stage Modification.

    Science.gov (United States)

    Haydl, Alexander M; Breit, Bernhard

    2015-12-14

    Natural products of polyketide origin with a high level of symmetry, in particular C2 -symmetric diolides as a special macrolactone-based product class, often possess a broad spectrum of biological activity. An efficient route to this important structural motif was developed as part of a concise and highly convergent synthesis of clavosolide A. This strategy features an atom-economic "head-to-tail" dimerization by the stereoselective rhodium-catalyzed addition of carboxylic acids to terminal allenes with the simultaneous construction of two new stereocenters. The excellent efficiency and selectivity with which the C2 -symmetric core structures were obtained are remarkable considering the outcome under classical dimerization conditions. Furthermore, this approach facilitates late-stage modification and provides ready access to potential new lead structures. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Water Contact Angle Dependence with Hydroxyl Functional Groups on Silica Surfaces under CO2 Sequestration Conditions.

    Science.gov (United States)

    Chen, Cong; Zhang, Ning; Li, Weizhong; Song, Yongchen

    2015-12-15

    Functional groups on silica surfaces under CO2 sequestration conditions are complex due to reactions among supercritical CO2, brine and silica. Molecular dynamics simulations have been performed to investigate the effects of hydroxyl functional groups on wettability. It has been found that wettability shows a strong dependence on functional groups on silica surfaces: silanol number density, space distribution, and deprotonation/protonation degree. For neutral silica surfaces with crystalline structure (Q(3), Q(3)/Q(4), Q(4)), as silanol number density decreases, contact angle increases from 33.5° to 146.7° at 10.5 MPa and 318 K. When Q(3) surface changes to an amorphous structure, water contact angle increases 20°. Water contact angle decreases about 12° when 9% of silanol groups on Q(3) surface are deprotonated. When the deprotonation degree increases to 50%, water contact angle decreases to 0. The dependence of wettability on silica surface functional groups was used to analyze contact angle measurement ambiguity in literature. The composition of silica surfaces is complicated under CO2 sequestration conditions, the results found in this study may help to better understand wettability of CO2/brine/silica system.

  14. The Picard group of the moduli space of r-Spin Riemann surfaces

    DEFF Research Database (Denmark)

    Randal-Williams, Oscar

    2012-01-01

    An r-Spin Riemann surface is a Riemann surface equipped with a choice of rth root of the (co)tangent bundle. We give a careful construction of the moduli space (orbifold) of r-Spin Riemann surfaces, and explain how to establish a Madsen–Weiss theorem for it. This allows us to prove the “Mumford...... conjecture” for these moduli spaces, but more interestingly allows us to compute their algebraic Picard groups (for g≥10, or g≥9 in the 2-Spin case). We give a complete description of these Picard groups, in terms of explicitly constructed line bundles....

  15. Study on the surface hydroxyl group on solid breeding materials by infrared absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Satoru; Taniguchi, Masaki [Tokyo Univ. (Japan). Faculty of Engineering

    1996-10-01

    Hydroxyl groups on the surface of Li{sub 2}O were studied by using a diffuse reflectance method with Fourier transform infrared absorption spectroscopy at high temperature up to 973K under controlled D{sub 2}O or D{sub 2} partial pressure. It was found that hydroxyl groups could exist on Li{sub 2}O surface up to 973K under Ar atmosphere. Under D{sub 2}O containing atmosphere, only the sharp peak at 2520cm{sup -1} was observed at 973K in the O-D stretching vibration region. Below 973K, multiple peaks due to the surface -OD were observed and they showed different behavior with temperature or atmosphere. Multiple peaks mean that surface is not homogeneous for D{sub 2}O adsorption. Assignment of the observed peaks to the surface bonding structure was also discussed. (author)

  16. 3-Carboxyquinolin-1-ium-2-carboxylate monohydrate

    Directory of Open Access Journals (Sweden)

    Qing Zhang

    2012-03-01

    Full Text Available The title compound, C11H7NO4·H2O, contains a 3-carboxyquinolin-1-ium-2-carboxylate (qda zwitterion and one water molecule. In the crystal, pairs of N—H...O hydrogen bonds link the molecules into inversion dimers, and these dimers are further connected by O—H...O hydrogen bonds into a three-dimensional supramolecular architecture. In addition, π–π interactions occur between pyridine and benzene rings from different qda ligands [centroid–centroid distance = 3.749 (1 Å] and the dihedral angles of the –CO2H and –CO2 groups to the quinoline system are 8.47 (3 and 88.16 (6°, respectively.

  17. Ion exchange properties of carboxylate bagasse

    International Nuclear Information System (INIS)

    Nada, A.M.A.; Hassan, M.L.

    2005-01-01

    Bagasse fibers were chemically modified using three different reactions: esterification using monochloro acetic acid, esterification using succinic anhydride, and oxidation using sodium periodate and sodium chlorite to prepare cation exchanger bearing carboxylic groups. Bagasse was crosslinked using epichlorohydrin before chemical modification to avoid loss of its constituents during the chemical modification. The structure of the prepared derivatives was proved using Fourier transform infrared (FTIR) and chemical methods. The ability of the prepared bagasse cation exchangers to adsorb heavy metal ions (Cu +2 , Ni +2 , Cr +3 , Fe +3 ), on a separate basis or in a mixture of them, at different metal ion concentration was tested. Thermal stability of the different bagasse derivative was studied using thermogravimetric analysis (TGA)

  18. Surface nucleation and independent growth of Ce(OH)4 within confinement space on modified carbon black surface to prepare nano-CeO2 without agglomeration

    Science.gov (United States)

    Zhang, Xinyue; Xia, Chunhui; Li, Kaitao; Lin, Yanjun

    2018-04-01

    Highly dispersed negative carboxyl groups can be formed on carbon black (CB) surface modified with strong nitric acid. Therefore positive cations can be uniformly absorbed by carboxyl groups and precipitated within a confinement space on modified CB surface to prepare highly dispersed nanomaterials. In this paper, the formation and dispersion status of surface negative carboxyl groups, adsorption status of Ce3+, surface confinement nucleation, crystallization and calcination process were studied by EDS, SEM, and laser particle size analysis. The results show that the carboxyl groups formed on modified CB surface are highly dispersed, and Ce3+ cations can be uniformly anchored by carboxyl groups. Therefore, highly dispersed Ce3+ can react with OH- within a confinement surface region to form positive nano-Ce(OH)4 nuclei which also can be adsorbed by electrostatic attraction. After independent growth of Ce(OH)4 without agglomeration, highly dispersed CeO2 nanoparticles without agglomeration can be prepared together with the help of effectively isolates by CO2 released in the combustion of CB.

  19. Effect of surface ethoxy groups on photoactivity of TiO2 nanocrystals

    International Nuclear Information System (INIS)

    Tian Lihong; Deng Kejian; Ye Liqun; Zan Lin

    2011-01-01

    TiO 2 nanocrystals modified by ethoxy groups were prepared by a facile nonhydrolytic solvothermal method and characterized by XRD, TEM, TG-DTA and XPS, which showed an enhanced visible-light photocatalytic activity on the degradation of Rhodamine B compared with TiO 2 modified by benzyloxy groups and the 'naked' TiO 2 . The adsorption and degradation pathway of Rhodamine B on TiO 2 modified by ethoxy groups were also investigated. The zeta-potential (ζ) results showed that the TiO 2 modified by ethoxy groups had high negative surface charge, which incited the positive -N(Et) 2 group of RhB absorbing on the TiO 2 surface and preferably led the N-dealkylation pathway under visible light irradiation.

  20. 2-Oxo-1,2-dihydroquinoline-4-carboxylic acid monohydrate

    Directory of Open Access Journals (Sweden)

    Yassir Filali Baba

    2016-06-01

    Full Text Available In the title compound, C10H7NO3·H2O, O—H...O hydrogen bonds involving the carboxyl groups, the keto groups and the lattice water molecules form stepped sheets approximately parallel to {010} which are tied together by pairwise N—H...O interactions. The asymmetric unit contains two independent quinolone derivatives and two water molecules, one of which is disordered over two positions, of equal occupancy.

  1. Ru(II)-Catalyzed Oxidative Heck-Type Olefination of Aromatic Carboxylic Acids with Styrenes through Carboxylate-Assisted C-H Bond Activation.

    Science.gov (United States)

    Dana, Suman; Mandal, Anup; Sahoo, Harekrishna; Mallik, Sumitava; Grandhi, Gowri Sankar; Baidya, Mahiuddin

    2018-02-02

    A straightforward synthesis of 2-styrylbenzoic acids from aryl carboxylic acids is disclosed through a carboxylate-assisted coupling under Ru(II) catalysis. This protocol is simple and exhibits broad scope with high tolerance of common organic functional groups, providing good to excellent yields of diverse olefinated products. The efficacy of this protocol has been showcased through sequential syntheses of isochromanone, isocoumarin, and formal synthesis of anacardic acid derivative in good yields.

  2. The Conversion of Carboxylic Acids to Ketones: A Repeated Discovery

    Science.gov (United States)

    Nicholson, John W.; Wilson, Alan

    2004-09-01

    This article describes the history of the reaction converting carboxylic acids to ketones. The reaction has been rediscovered several times, yet has actually been known for centuries. The best known version of the process is the Dakin West reaction (1928), which applies to α-amino acids and also involves the simultaneous conversion of the amine group to amido functionality. Unlike other examples, this particular reaction has attracted a reasonable amount of attention and it appears to be better known than the conversion of simple carboxylic acids to ketones. However, this reaction was described as long ago as 1612, when Beguin published an account of it in his book, Tyrocinium Chymicum . Since then, many chemists have rediscovered the reaction, apparently independently. One of the earliest modern accounts was by W. H. Perkin, Sr., in 1886, who made various simple ketones by refluxing the appropriate carboxylic acids with base. However, this work has been largely ignored, including by his son, W. H. Perkin, Jr., who used a more complicated base-catalyzed ketonization to prepare small ring compounds in the early years of the 20th century. Other articles detailing the application of ketonization to organic acids are discussed, including our own work, which employed the process to crosslink carboxylated polymers for possible technical application in coatings. Despite its relative obscurity, the reaction was used by Woodward et al. in the total synthesis of strychnine, reported in 1963, and this is discussed in detail at the end of the article. See Featured Molecules .

  3. Effect of surface hydroxyl groups on heat capacity of mesoporous silica

    Science.gov (United States)

    Marszewski, Michal; Butts, Danielle; Lan, Esther; Yan, Yan; King, Sophia C.; McNeil, Patricia E.; Galy, Tiphaine; Dunn, Bruce; Tolbert, Sarah H.; Hu, Yongjie; Pilon, Laurent

    2018-05-01

    This paper quantifies the effect of surface hydroxyl groups on the effective specific and volumetric heat capacities of mesoporous silica. To achieve a wide range of structural diversity, mesoporous silica samples were synthesized by various methods, including (i) polymer-templated nanoparticle-based powders, (ii) polymer-templated sol-gel powders, and (iii) ambigel silica samples dried by solvent exchange at room temperature. Their effective specific heat capacity, specific surface area, and porosity were measured using differential scanning calorimetry and low-temperature nitrogen adsorption-desorption measurements. The experimentally measured specific heat capacity was larger than the conventional weight-fraction-weighted specific heat capacity of the air and silica constituents. The difference was attributed to the presence of OH groups in the large internal surface area. A thermodynamic model was developed based on surface energy considerations to account for the effect of surface OH groups on the specific and volumetric heat capacity. The model predictions fell within the experimental uncertainty.

  4. Hydrated electron: a destroyer of perfluorinated carboxylates?

    International Nuclear Information System (INIS)

    Huang Li; Dong Wenbo; Hou Huiqi

    2006-01-01

    As a class, perfluorinated carboxylate (PFCA) was ranked among the most prominent organohalogen contaminants in environment with respect to thermal, chemical and biological inertness. Hydrated electron (e aq - ), a highly reactive and strongly reductive species, has been reported to readily decompose perfluoroaromatic compounds via intermolecular electron transfer process in aqueous solution. Question then arose: what would happen if perfluorinated carboxylates encountered with hydrated electron? Original laboratory trial on the interaction between F(CF 2 ) n COO - (n=1, 3, 7) and hydrated electron was attempted by using laser flash photolysis technique in this research work. Abundant hydrated electron (e aq - ) could be produced by photolysis of 1.25 x 10 -4 M K 4 Fe(CN) 6 in nitrogen saturated water. In the presence of F(CF 2 ) n COO - (n=1, 3, 7), the decay of e aq - was observed to enhance dramatically, indicating e aq - was able to attack PFCAs. On addition of perfluorinated carboxylates, the loss of e aq - was mainly due to the following channels. By mixing the solution of K 4 Fe(CN) 6 with excess K 3 Fe(CN) 6 and PFCAs, e aq - turned to decayed corresponding to mixed first- and second-order kinetics. Rate constants for the reactions of e aq - with PFCAs could be then easily determined by monitoring the decay of e aq - absorption at 690 nm. Since perfluorinated carboxylates were salts, the influence of ionic strength on k 3 was examined systematically by carrying out experiments of varying ionic strength ranging from 0.009 up to 0.102 M by adding NaClO 4 . In this manner, the second order rate constants for e-aq with CF 3 COO - , C 3 F 7 COO - , C 7 F 15 COO - were derived to be (1.9±0.2) x 10 6 M -1 S -1 (μ=0), (7.1±0.2) x 10 6 M -1 S -1 (μ=0) and (1.7±0.5) x10 7 M -1 S -1 (μ=0.009 M) respectively. Apparently, the length of F(CF 2 ) n group exerted substantial influence on the rate constant. Further study on byproducts analysis by ion chromatography

  5. AFM imaging and analysis of local mechanical properties for detection of surface pattern of functional groups

    Energy Technology Data Exchange (ETDEWEB)

    Knotek, Petr, E-mail: petr.knotek@upce.cz [University of Pardubice, Faculty of Chemical Technology, Joint Laboratory of Solid State Chemistry of IMC ASCR and University of Pardubice, Studentska 573, 532 10 Pardubice (Czech Republic); Chanova, Eliska; Rypacek, Frantisek [Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic, Heyrovskeho sq. 2, 162 06 Prague (Czech Republic)

    2013-05-01

    In this work we evaluate the applicability of different atomic force microscopy (AFM) modes, such as Phase Shift Imaging, Atomic Force Acoustic Microscopy (AFAM) and Force Spectroscopy, for mapping of the distribution pattern of low-molecular-weight biomimetic groups on polymer biomaterial surfaces. Patterns with either random or clustered spatial distribution of bioactive peptide group derived from fibronectin were prepared by surface deposition of functional block copolymer nano-colloids and grafted with RGDS peptide containing the sequence of amino acids arginine–glycine–aspartic acid–serine (conventionally labeled as RGDS) and carrying biotin as a tag. The biotin-tagged peptides were labeled with 40 nm streptavidin-modified Au nanospheres. The peptide molecules were localized through the detection of bound Au nanospheres by AFM, and thus, the surface distribution of peptides was revealed. AFM techniques capable of monitoring local mechanical properties of the surface were proved to be the most efficient for identification of Au nano-markers. The efficiency was successfully demonstrated on two different patterns, i.e. random and clustered distribution of RGDS peptides on structured surface of the polymer biomaterial. Highlights: ► Bioactive peptides for cell adhesion on PLA-b-PEO biomimetic surface were visualized. ► The biotin-tagged RGDS peptides were labeled with streptavidin-Au nanospheres. ► The RGDS pattern was detected using different atomic force microscopy (AFM) modes. ► Phase Shift Image was proved to be suitable method for studying peptide distribution.

  6. A chord diagrammatic presentation of the mapping class group of a once bordered surface

    DEFF Research Database (Denmark)

    Bene, Alex

    2010-01-01

    of Teichmüller space with a discrete set objects. In particular, it leads to an infinite, but combinatorially simple, presentation of the mapping class group of an orientable surface. In this note, we give a presentation of a full mapping class group equivariant subgroupoid of the Ptolemy groupoid......The Ptolemy groupoid is a combinatorial groupoid generated by elementary moves on marked trivalent fatgraphs with three types of relations. Through the fatgraph decomposition of Teichmüller space, the Ptolemy groupoid is a mapping class group equivariant subgroupoid of the fundamental path groupoid...

  7. A Chord Diagrammatic Presentation of the Mapping Class Group of a Once Bordered Surface

    DEFF Research Database (Denmark)

    Bene, Alex

    groupoid of Teichm\\"uller space with a discrete set objects. In particular, it leads to an infinite, but combinatorially simple, presentation of the mapping class group of an orientable surface. In this note, we give a presentation of a full mapping class group equivariant subgroupoid of the Ptolemy......The Ptolemy groupoid is a combinatorial groupoid generated by elementary moves on marked trivalent fatgraphs with three types of relations. Through the fatgraph decomposition of Teichm\\"uller space, the Ptolemy groupoid is a mapping class group equivariant subgroupoid of the fundamental path...

  8. Carboxyl functionalized carbon fibers with preserved tensile strength and electrochemical performance used as anodes of structural lithium-ion batteries

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Mengjie [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Wang, Shubin, E-mail: shubinwang@buaa.edu.cn [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Key Laboratory of Aerospace Materials and Performance (Ministry of Education), School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Yu, Yalin; Feng, Qihang; Yang, Jiping; Zhang, Boming [School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2017-01-15

    Highlights: • Carboxyl functionalized CF is acquired by simple chemical oxidation method. • These CF have preserved the tensile strength, better electrochemical properties. • The presence of H{sub 3}PO{sub 4} prevented the turbostratic carbon from over-oxidization. • There CF can be used as anodes of multifunctional structural battery. • The preservation and improvement is result from the hindered over-oxidization. - Abstract: Carboxyl functionalized carbon fibers with preserved tensile strength and electrochemical properties were acquired through a simple chemical oxidation method, and the proposed underlying mechanism was verified. The surface of carboxyl functionalizing carbon fibers is necessary in acquiring functional groups on the surface of carbon fibers to further improve the thermal, electrical or mechanical properties of the fibers. Functionalization should preserve the tensile strength and electrochemical properties of carbon fibers, because the anodes of structural batteries need to have high strength and electrochemical properties. Functionalized with mixed H{sub 2}SO{sub 4}/HNO{sub 3} considerably reduced the tensile strength of carbon fibers. By contrast, the appearance of H{sub 3}PO{sub 4} preserved the tensile strength of functionalized carbon fibers, reduced the dispersion level of tensile strength values, and effectively increased the concentration of functional acid groups on the surface of carbon fibers. The presence of phosphoric acid hindered the over-oxidation of turbostratic carbon, and consequently preserved the tensile strength of carbon fibers. The increased proportion of turbostratic carbon on the surface of carbon fibers concurrently enhanced the electrochemical properties of carbon fibers.

  9. Simple surface modification of poly(dimethylsiloxane) for DNA hybridization

    Science.gov (United States)

    Zhou, Jinwen; Voelcker, Nicolas H.; Ellis, Amanda V.

    2010-01-01

    Here, we present a simple chemical modification of poly(dimethylsiloxane) (PDMS) by curing a mixture of 2 wt% undecylenic acid (UDA) in PDMS prepolymer on a gold-coated glass slide. This gold slide had been previously pretreated with a self-assembled hydrophilic monolayer of 3-mercaptopropionic acid (MPA). During curing of the UDA∕PDMS prepolymer, the hydrophilic UDA carboxyl moieties diffuses toward the hydrophilic MPA carboxyl moieties on the gold surface. This diffusion of the UDA within the PDMS prepolymer to the surface is a direct result of surface energy minimization. Once completely cured, the PDMS is peeled off the gold substrate, thereby exposing the interfacial carboxyl groups. These groups are then available for subsequent attachment of 5′-amino terminated DNA oligonucleotides via amide linkages. Our results show that the covalently tethered oligonucleotides can successfully capture fluorescein-labeled complementary oligonucleotides via hybridization, which are visualized using fluorescence microscopy. PMID:21264061

  10. Influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for the synthesis of dimethyl carbonate

    Science.gov (United States)

    Zhang, Guoqiang; Li, Zhong; Zheng, Huayan; Hao, Zhiqiang; Wang, Xia; Wang, Jiajun

    2016-12-01

    Activated carbon (AC) supported Cu catalysts are employed to study the influence of surface oxygenated groups on the formation of active Cu species and the catalytic activity of Cu/AC catalyst for oxidative carbonylation of methanol to dimethyl carbonate (DMC). The AC supports are thermal treated under different temperatures in order to adjust the levels of surface oxygenated groups. The AC supports are characterized by BET, TPD-MS and XRD, and the Cu/AC catalysts are characterized by BET, XRD, TEM, XPS, AAS, CH3OH-TPD and N2O chemisorption. The results show that as the treatment temperature is below 800 °C, the BET surface area of the corresponding AC supports are nearly unchanged and close to that of the original AC (1529.6 m2/g). But as the thermal treatment temperature is elevated from 1000 to 1600 °C, the BET surface area of AC supports gradually decreases from 1407.6 to 972.2 m2/g. After loading of Cu, the BET surface area of copper catalysts is in the range of 834.4 to 1545.3 m2/g, which is slightly less than that of the respective supports. When AC is thermal treated at 400 and 600 °C, the unstable carboxylic acid and anhydrides groups are selectively removed, which has weakened the mobility and agglomeration of Cu species during the calcination process, and thus improve the Cu species dispersion over AC support. But as the treatment temperature is elevated from 600 °C to 1200 °C, the Cu species dispersion begins to decline suggesting further removal of stable surface oxygenated groups is unfavorable for Cu species dispersion. Moreover, higher thermal treatment temperature (above 1200 °C) promotes the graphitization degree of AC and leds to the decrease of Cu loading on AC support. Meanwhile, the removal of surface oxygenated groups by thermal treatment is conducive to the formation of more π-sites, and thus promote the reduction of Cu2+ to Cu+ and Cu0 as active centers. The specific surface area of (Cu+ + Cu0) is improved by thermal treatment of AC

  11. Crystal structure of ethyl 2,4-dichloroquinoline-3-carboxylate

    Directory of Open Access Journals (Sweden)

    Alberto Cabrera

    2015-12-01

    Full Text Available In the crystal structure of the title compound, C12H9Cl2NO2, the mean planes through the quinoline and carboxylate groups have r.m.s. deviations of 0.006 and 0.021 Å, respectively, and form a dihedral angle of 87.06 (19°. In the crystal, molecules are linked via very weak C—H...O hydrogen bonds, forming chains, which propagate along the c-axis direction.

  12. Effect of the surface oxygen groups on methane adsorption on coals

    Energy Technology Data Exchange (ETDEWEB)

    Hao Shixiong [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Department of Chemical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China); Wen Jie [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Yu Xiaopeng [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Department of Chemical Engineering, Sichuan University of Science and Engineering, Zigong 643000 (China); Chu Wei, E-mail: chuwei1965_scu@yahoo.com [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China)

    2013-01-01

    Highlights: Black-Right-Pointing-Pointer We modified one coal with H{sub 2}O{sub 2}, (NH{sub 4}){sub 2}S{sub 2}O{sub 8} and HNO{sub 3} respectively, to prepare coal samples with different surface properties. Black-Right-Pointing-Pointer The oxygen groups on coal surface were characterized by XPS. Black-Right-Pointing-Pointer The textures of the coal samples were investigated by N{sub 2} adsorption at 77 K. Black-Right-Pointing-Pointer The adsorption behaviors were measured by volumetric method. Black-Right-Pointing-Pointer There was a negative correlation between methane saturated adsorption capacity and the O{sub total}/C{sub total}. - Abstract: To investigate the influence of surface oxygen groups on methane adsorption on coals, one bituminous coal was modified with H{sub 2}O{sub 2}, (NH{sub 4}){sub 2}S{sub 2}O{sub 8} and HNO{sub 3} respectively, to prepare coal samples with different surface properties. The oxygen groups on coal surface were characterized by X-ray photoelectron spectroscopy (XPS). The textures of the coal samples were investigated by N{sub 2} adsorption at 77 K. Their surface morphologies were analyzed by scanning electron microscopy (SEM). The methane adsorption behaviors of these coal samples were measured at 303 K in pressure range of 0-5.3 MPa by volumetric method. The adsorption data of methane were fitted to the Langmuir model and Dubinin-Astakhov (D-A) model. The fitting results showed that the D-A model fitted the isotherm data better than the Langmuir model. It was observed that there was, in general, a positive correlation between the methane saturated adsorption capacity and the micropore volume of coals while a negative correlation between methane saturated adsorption capacity and the O{sub total}/C{sub total}. The methane adsorption capacity was determined by the coal surface chemistry when the microporosity parameters of two samples were similar. Coal with a higher amount of oxygen surface groups, and consequently with a less

  13. Chiral metal-organic frameworks bearing free carboxylic acids for organocatalyst encapsulation.

    Science.gov (United States)

    Liu, Yan; Xi, Xiaobing; Ye, Chengcheng; Gong, Tengfei; Yang, Zhiwei; Cui, Yong

    2014-12-08

    Two chiral carboxylic acid functionalized micro- and mesoporous metal-organic frameworks (MOFs) are constructed by the stepwise assembly of triple-stranded heptametallic helicates with six carboxylic acid groups. The mesoporous MOF with permanent porosity functions as a host for encapsulation of an enantiopure organic amine catalyst by combining carboxylic acids and chiral amines in situ through acid-base interactions. The organocatalyst-loaded framework is shown to be an efficient and recyclable heterogeneous catalyst for the asymmetric direct aldol reactions with significantly enhanced stereoselectivity in relative to the homogeneous organocatalyst. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Surface-Level Diversity and Decision-Making in Groups: When Does Deep-Level Similarity Help?

    OpenAIRE

    2006-01-01

    Abstract We examined how surface-level diversity (based on race) and deep-level similarities influenced three-person decision-making groups on a hidden-profile task. Surface-level homogeneous groups perceived their information to be less unique and spent less time on the task than surface-level diverse groups. When the groups were given the opportunity to learn about their deep-level similarities prior to t...

  15. Carboxyl functionalization of carbon fibers via aryl diazonium reaction in molten urea to enhance interfacial shear strength

    International Nuclear Information System (INIS)

    Wang, Yuwei; Meng, Linghui; Fan, Liquan; Wu, Guangshun; Ma, Lichun; Zhao, Min; Huang, Yudong

    2016-01-01

    Graphical abstract: - Highlights: • Carbon fibers are functionalized with benzoic acid groups via aryl diazonium reaction. • Interfacial shear strength of the carbon fibers increases by 66%. • Tensile strength of the carbon fibers is preserved after grafting reaction. • The treatment in molten urea can improve modification efficiency greatly. • Using molten urea as the reaction medium can avoid pollution from organic solvents. - Abstract: Using molten urea as the solvent, carbon fibers were functionalized with carboxylic acid groups via aryl diazonium reaction in 15 min to improve their interfacial bonding with epoxy resin. The surface functionalization was quantified by X-ray photoelectron spectroscopy, which showed that the relative surface coverage of carboxylic acid groups increased from an initial percentage of 3.17–10.41%. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 66%. Meanwhile, the technique did not adopt any pre-oxidation step to produce functional groups prior to grafting and was shown to maintain the tensile strength of the fibers. This methodology provided a rapid, facile and economically viable route to produce covalently functionalized carbon fibers in large quantities with an eco-friendly method.

  16. Carboxyl functionalization of carbon fibers via aryl diazonium reaction in molten urea to enhance interfacial shear strength

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yuwei [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Meng, Linghui [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Fan, Liquan [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); College of Materials Science and Engineering, Qiqihar University, Qiqihar 161006 (China); Wu, Guangshun; Ma, Lichun; Zhao, Min [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China); Huang, Yudong, E-mail: ydhuang.hit1@yahoo.com.cn [School of Chemical Engineering and Technology, Harbin Institute of Technology, Harbin 150001 (China)

    2016-01-30

    Graphical abstract: - Highlights: • Carbon fibers are functionalized with benzoic acid groups via aryl diazonium reaction. • Interfacial shear strength of the carbon fibers increases by 66%. • Tensile strength of the carbon fibers is preserved after grafting reaction. • The treatment in molten urea can improve modification efficiency greatly. • Using molten urea as the reaction medium can avoid pollution from organic solvents. - Abstract: Using molten urea as the solvent, carbon fibers were functionalized with carboxylic acid groups via aryl diazonium reaction in 15 min to improve their interfacial bonding with epoxy resin. The surface functionalization was quantified by X-ray photoelectron spectroscopy, which showed that the relative surface coverage of carboxylic acid groups increased from an initial percentage of 3.17–10.41%. Mechanical property test results indicated that the aryl diazonium reaction in this paper could improve the interfacial shear strength by 66%. Meanwhile, the technique did not adopt any pre-oxidation step to produce functional groups prior to grafting and was shown to maintain the tensile strength of the fibers. This methodology provided a rapid, facile and economically viable route to produce covalently functionalized carbon fibers in large quantities with an eco-friendly method.

  17. Helioseismic measurements in the solar envelope using group velocities of surface waves

    Science.gov (United States)

    Vorontsov, S. V.; Baturin, V. A.; Ayukov, S. V.; Gryaznov, V. K.

    2014-07-01

    At intermediate- and high-degree l, solar p and f modes can be considered as surface waves. Using variational principle, we derive an integral expression for the group velocities of the surface waves in terms of adiabatic eigenfunctions of normal modes, and address the benefits of using group-velocity measurements as a supplementary diagnostic tool in solar seismology. The principal advantage of using group velocities, when compared with direct analysis of the oscillation frequencies, comes from their smaller sensitivity to the uncertainties in the near-photospheric layers. We address some numerical examples where group velocities are used to reveal inconsistencies between the solar models and the seismic data. Further, we implement the group-velocity measurements to the calibration of the specific entropy, helium abundance Y, and heavy-element abundance Z in the adiabatically stratified part of the solar convective envelope, using different recent versions of the equation of state. The results are in close agreement with our earlier measurements based on more sophisticated analysis of the solar oscillation frequencies. These results bring further support to the downward revision of the solar heavy-element abundances in recent spectroscopic measurements.

  18. Microstructuring of thermo-mechanically highly stressed surfaces final report of the DFG research group 576

    CERN Document Server

    Rienäcker, Adrian; Knoll, Gunter; Bach, Friedrich-Wilhelm; Maier, Hans; Reithmeier, Eduard; Dinkelacker, Friedrich

    2015-01-01

    This contributed volume presents the final research results of the DFG Research Group 576, which is a joint initiative of five different institutes of the Leibniz Universität Hannover and the Universität Kassel, Germany. The research of the DFG Research Group 576 focuses on improving the tribological behavior of thermomechanically highly stressed surfaces, particularly on cylinder liner for combustion engines. The target audience primarily comprises researchers and experts in the field but the book may also be beneficial for graduate students who want to specialize in the field.

  19. Plastic scintillators with high loading of one or more metal carboxylates

    Science.gov (United States)

    Cherepy, Nerine; Sanner, Robert Dean

    2016-01-12

    In one embodiment, a material includes at least one metal compound incorporated into a polymeric matrix, where the metal compound includes a metal and one or more carboxylate ligands, where at least one of the one or more carboxylate ligands includes a tertiary butyl group, and where the material is optically transparent. In another embodiment, a method includes: processing pulse traces corresponding to light pulses from a scintillator material; and outputting a result of the processing, where the scintillator material comprises at least one metal compound incorporated into a polymeric matrix, the at least one metal compound including a metal and one or more carboxylate ligands, where at least one of the one or more carboxylate ligands has a tertiary butyl group, and where the scintillator material is optically transparent and has an energy resolution at 662 keV of less than about 20%.

  20. Different chemical groups modification on the surface of chitosan nonwoven dressing and the hemostatic properties.

    Science.gov (United States)

    Yan, Dong; Hu, Shihao; Zhou, Zhongzheng; Zeenat, Shah; Cheng, Feng; Li, Yang; Feng, Chao; Cheng, Xiaojie; Chen, Xiguang

    2018-02-01

    The hemostatic properties of surface modified chitosan nonwoven had been investigated. The succinyl groups, carboxymethyl groups and quaternary ammonium groups were introduced into the surface of chitosan nonwoven (obtained NSCS, CMCS and TMCS nonwoven, respectively). For blood clotting, absorbance value (0.105±0.03) of NSCS1 nonwoven was the smallest (CS 0.307±0.002, NSCS2 0.148±0.002, CMCS1 0.195±0.02, CMCS2 0.233±0.001, TMCS1 0.191±0.002, TMCS2 0.345±0.002), which indicated the stronger hemostatic potential. For platelet aggregation, adenosine diphosphate agonist was added to induce the nonwoven to adhered platelets. The aggregation of platelet with TMCS2 nonwoven was highest (10.97±0.16%). Further research of blood coagulation mechanism was discussed, which indicated NSCS and CMCS nonwoven could activate the intrinsic pathway of coagulation to accelerate blood coagulation. NSCS1 nonwoven showed the shortest hemostatic time (147±3.7s) and the lowest blood loss (0.23±0.05g) in a rabbit ear artery injury model. These results demonstrated that these surface modified chitosan nonwoven dressings could use as a promising hemostatic intervention, especially NSCS nonwoven dressing. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Roles of acidic functional groups of carbon fiber surfaces in enhancing interfacial adhesion behavior

    International Nuclear Information System (INIS)

    Park, Soo-Jin; Kim, Byung-Joo

    2005-01-01

    The gas phase ozone treatment was used as a method to bind acidic oxygen functional groups on carbon fiber surfaces. The ozone treatment on carbon fibers was varied with the ozone concentration and treatment time. Surface analyses of the carbon fibers before and after treatments were performed by FT-IR, X-ray photoelectron spectrometer (XPS), and dynamic contact angle measurements. Mechanical interfacial properties of the fibers/polymer composites were investigated by using critical stress intensity factor (K IC ) and critical energy release rate (G IC ) measurements. From the results of FT-IR and XPS, it was observed that the oxygen functional groups, such as -OH, O-C=O, C=O, and C-O, were attached on the carbon fiber surfaces after the ozone treatment. The mechanical interfacial properties of the composites also showed higher values than those of untreated composites. Ozone treatment is attributed to the increase of both the acidic functional groups and the degree of adhesion at interfaces between the fibers and polymeric resin in composites

  2. Photoelectron binding energy shifts observed during oxidation of group IIA, IIIA and IVA elemental surfaces

    International Nuclear Information System (INIS)

    Heide, P.A.W. van der

    2006-01-01

    An extensive re-evaluation of XPS binding energies (BE's) and binding energy shifts (ΔBE's) from metals, oxides and the carbonates of the group II, III and IVA elements (exceptions are Be, Mg and Hf) has been carried out using a substrate specific BE referencing approach. From this, O-1s BE's are found to fall into surface oxide, bulk oxide and carbonate groupings, with bulk oxides showing the lowest BE's followed by surface oxides (+∼1.5 eV) and then carbonates (+∼3.0 eV). The O-1s BE's from the bulk oxides also appear to scale with 1/d, where d is inter-atomic distance. The same is noted in the ΔBE's observed from the metallic counterparts during oxidation of the elemental surfaces. This, and the decreasing BE exhibited by Ca, Sr and Ba on oxidation is explained within the charge potential model as resulting from competing inter- and intra-atomic effects, and is shown to be consistent with partial covalency arguments utilizing Madulung potentials. The ΔBE's also fall into groups according to the elements location in the periodic table, i.e. s, p or d block. These trends open up the possibility of approximating ΔBE's arising from initial and final state effects, and bond distances

  3. Chemical reactions on platinum-group metal surfaces studied by synchrotron-radiation-based spectroscopy

    International Nuclear Information System (INIS)

    Kondoh, Hiroshi; Nakai, Ikuyo; Nagasaka, Masanari; Amemiya, Kenta; Ohta, Toshiaki

    2009-01-01

    A new version of synchrotron-radiation-based x-ray spectroscopy, wave-length-dispersive near-edge x-ray absorption fine structure (dispersive-NEXAFS), and fast x-ray photoelectron spectroscopy have been applied to mechanistic studies on several surface catalytic reactions on platinum-group-metal surfaces. In this review, our approach using above techniques to understand the reaction mechanism and actual application studies on three well-known catalytic surface reactions, CO oxidation on Pt(111) and Pd(111), NO reduction on Rh(111), and H 2 O formation on Pt(111), are introduced. Spectroscopic monitoring of the progress of the surface reactions enabled us to detect reaction intermediates and analyze the reaction kinetics quantitatively which provides information on reaction order, rate constant, pre-exponential factor, activation energy and etc. Such quantitative analyses combined with scanning tunneling microscopy and kinetic Monte Carlo simulations revealed significant contribution of the adsorbate configurations and their dynamic changes to the reaction mechanisms of the above fundamental catalytic surface reactions. (author)

  4. Direct enantioselective conjugate addition of carboxylic acids with chiral lithium amides as traceless auxiliaries.

    Science.gov (United States)

    Lu, Ping; Jackson, Jeffrey J; Eickhoff, John A; Zakarian, Armen

    2015-01-21

    Michael addition is a premier synthetic method for carbon-carbon and carbon-heteroatom bond formation. Using chiral dilithium amides as traceless auxiliaries, we report the direct enantioselective Michael addition of carboxylic acids. A free carboxyl group in the product provides versatility for further functionalization, and the chiral reagent can be readily recovered by extraction with aqueous acid. The method has been applied in the enantioselective total synthesis of the purported structure of pulveraven B.

  5. Direct Enantioselective Conjugate Addition of Carboxylic Acids with Chiral Lithium Amides as Traceless Auxiliaries

    Science.gov (United States)

    2016-01-01

    Michael addition is a premier synthetic method for carbon–carbon and carbon–heteroatom bond formation. Using chiral dilithium amides as traceless auxiliaries, we report the direct enantioselective Michael addition of carboxylic acids. A free carboxyl group in the product provides versatility for further functionalization, and the chiral reagent can be readily recovered by extraction with aqueous acid. The method has been applied in the enantioselective total synthesis of the purported structure of pulveraven B. PMID:25562717

  6. Proton migration along the membrane surface in the absence of charged or titratable groups

    International Nuclear Information System (INIS)

    Springer, A.

    2011-01-01

    Proton diffusion along membrane surfaces is thought to be essential for many cellular processes such as energy transduction. For example, proton diffusion along membrane surfaces is considered to be the dominant mechanism of proton exchange between membrane sites of high and low proton concentrations. For the investigation of this mechanism, kinetic experiments on proton diffusion are evaluated to determine the ability of lipid membranes to retain protons on their surfaces. Experiments on different lipid bilayer membranes (DPhPC, DPhPE and GMO) are performed under the influence of two types of mobile buffer molecules (Capso, NH4CL). During these experiments the surface diffusion of photolytically released protons is visualized in terms of fluorescence changes of a lipid bound pH-sensitive dye (DHPE +fluorescein). The protons under investigation are released by flash photolysis of a hydrophobic caged compound (DMCM, caged diethyl phosphate). The experimental data confirm the existence of an energy barrier, which prevents the protons from escaping into the bulk. So far this effect was attributed to the proton binding to titrateable groups (e.g. ethanolamine) or electrostatic forces created by charged moieties (e.g. phosphate groups) on the membrane/water interface. However, upon removal of the titrateable groups and charged moieties from the membrane surface, a significant energy barrier remained as indicated by the experiments with glycerol monooleate (GMO) bilayers. To estimate the size of the barrier a semi-analytical model is presented that describes the two and three dimensional proton diffusion and the related physical and chemical processes. Common models describe surface proton diffusion as a series of subsequent hopping processes between membrane-anchored buffer molecules. Our experiments provide evidence for an alternative model. We released membrane-bound caged protons by UV flashes and monitored their arrival at distant sites s by fluorescence

  7. Substrate specificity within a family of outer membrane carboxylate channels.

    Directory of Open Access Journals (Sweden)

    Elif Eren

    2012-01-01

    Full Text Available Many Gram-negative bacteria, including human pathogens such as Pseudomonas aeruginosa, do not have large-channel porins. This results in an outer membrane (OM that is highly impermeable to small polar molecules, making the bacteria intrinsically resistant towards many antibiotics. In such microorganisms, the majority of small molecules are taken up by members of the OprD outer membrane protein family. Here we show that OprD channels require a carboxyl group in the substrate for efficient transport, and based on this we have renamed the family Occ, for outer membrane carboxylate channels. We further show that Occ channels can be divided into two subfamilies, based on their very different substrate specificities. Our results rationalize how certain bacteria can efficiently take up a variety of substrates under nutrient-poor conditions without compromising membrane permeability. In addition, they explain how channel inactivation in response to antibiotics can cause resistance but does not lead to decreased fitness.

  8. Simple approach to carboxyl-rich materials through low-temperature heat treatment of hydrothermal carbon in air

    Energy Technology Data Exchange (ETDEWEB)

    Chen Zhen; Ma Lijian; Li Shuqiong; Geng Junxia; Song Qiang; Liu Jun; Wang Chunli; Wang Hang; Li Juan [College of Chemistry, Sichuan University, Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Chengdu 610064 (China); Qin Zhi [Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Li Shoujian, E-mail: sjli000616@scu.edu.cn [College of Chemistry, Sichuan University, Key Laboratory of Radiation Physics and Technology (Sichuan University), Ministry of Education, Chengdu 610064 (China)

    2011-08-01

    It was found that a large number of oxygen-containing functional groups (OFGs) could be created on the surface of hydrothermal carbon (HTC) by simply heating at lower temperature in air during the course of our preliminary experiments which focused on oxidation pre-treatment of pristine HTC for the purpose of grafting functionalization. Especially carboxyl groups on HTC would increase significantly, from 0.53 to 3.70 mmol/g after heat treatment at 300 deg. C. So, effects of heat-treatment on the OFGs on the carbon microsphere were deeply studied to confirm and explain the findings. Experiments involving different materials (HTC, activated carbon and glucose) were performed under varying conditions (heating temperature and time, in air or in Ar atmosphere). A reaction mechanism for newly generating carboxyl groups on HTC surface during heat-treatment process was supposed based on the results from the sample characterization using Boehm titrations, infrared spectra, X-ray photoelectron spectroscopy, energy dispersive spectrometry and elemental analysis. In addition, the as heat-treated product has excellent sorption capability for Pb{sup 2+} and Cd{sup 2+} ions.

  9. Synthesis and characterization of silver nanoparticles from (bis)alkylamine silver carboxylate precursors

    Energy Technology Data Exchange (ETDEWEB)

    Uznanski, Pawel, E-mail: puznansk@cbmm.lodz.pl; Zakrzewska, Joanna [Centre of Molecular and Macromolecular Studies, PAS (Poland); Favier, Frederic, E-mail: fredf@univ-montp2.fr [Université Montpellier II, ICGM - UMR5253- Equipe AIME (France); Kazmierski, Slawomir; Bryszewska, Ewa [Centre of Molecular and Macromolecular Studies, PAS (Poland)

    2017-03-15

    A comparative study of amine and silver carboxylate adducts [R{sub 1}COOAg-2(R{sub 2}NH{sub 2})] (R{sub 1} = 1, 7, 11; R{sub 2} = 8, 12) as a key intermediate in NPs synthesis is carried out via differential scanning calorimetry, solid-state FT-infrared spectroscopy, {sup 13}C CP MAS NMR, powder X-ray diffraction and X-ray photoelectron spectroscopy, and various solution NMR spectroscopies ({sup 1}H and {sup 13}C NMR, pulsed field gradient spin-echo NMR, and ROESY). It is proposed that carboxyl moieties in the presence of amine ligands are bound to silver ions via chelating bidentate type of coordination as opposed to bridging bidentate coordination of pure silver carboxylates resulting from the formation of dimeric units. All complexes are packed as lamellar bilayer structures. Silver carboxylate/amine complexes show one first-order melting transition. The evidence presented in this study shows that phase behavior of monovalent metal carboxylates are controlled, mainly, by head group bonding. In solution, insoluble silver salt is stabilized by amine molecules which exist in dynamic equilibrium. Using (bis)amine-silver carboxylate complex as precursor, silver nanoparticles were fabricated. During high-temperature thermolysis, the (bis)amine-carboxylate adduct decomposes to produce silver nanoparticles of small size. NPs are stabilized by strongly interacting carboxylate and trace amounts of amine derived from the silver precursor interacting with carboxylic acid. A corresponding aliphatic amide obtained from silver precursor at high-temperature reaction conditions is not taking part in the stabilization. Combining NMR techniques with FTIR, it was possible to follow an original stabilization mechanism.

  10. Highly visible-light luminescence properties of the carboxyl-functionalized short and ultrashort MWNTs

    International Nuclear Information System (INIS)

    Luo Yongsong; Xia Xiaohong; Liang Ying; Zhang Yonggang; Ren Qinfeng; Li Jialin; Jia Zhijie; Tang Yiwen

    2007-01-01

    Luminescence of the short multiwalled carbon nanotubes (MWNTs) conjugated with carboxylic acid groups has been studied. The results show that the carboxyl-functionalized short MWNTs could emit luminescence and the emission peak appears at 500 nm with a corresponding optimal excitation wavelength centering at 310 nm. When the short MWNTs are filtered through 0.15 μm polytetrafluoroethylene (PTFE) membrane, the ultrashort MWNTs are obtained from the filtrate. An interesting feature for the ultrashort MWNTs is that the emission intensity is strengthened and the peak is slightly blue shifted to 460 nm. This result indicates that the luminescence properties of MWNTs are strongly affected by the tube length. After chemical oxidization cutting, defects and carboxylic acid groups at the tube end and/or sidewall can be produced; the more shorten of MWNTs, the better dispersion and carboxylic passivation of the nanotubes, and the more intense luminescence emissions. The broad emissions are logically attributed to the trapping of excitation energy by defect sites in the carboxyl-functionalized nanotube structure. - Graphical abstract: Luminescence of the short and ultrashort multiwalled carbon nanotubes (MWNTs) conjugated with carboxylic acid groups, which is logically attributed to the trapping of excitation energy by defect sites, has been studied

  11. In situ SERS and X-ray photoelectron spectroscopy studies on the pH-dependant adsorption of anthraquinone-2-carboxylic acid on silver electrode

    Science.gov (United States)

    Li, Dan; Jia, Shaojie; Fodjo, Essy Kouadio; Xu, Hu; Wang, Yuhong; Deng, Wei

    2016-03-01

    In this study, in situ surface-enhanced Raman scattering (SERS) spectroelectrochemistry and angle-resolved X-ray photoelectron spectroscopy (AR-XPS) are used to investigate the redox reaction and adsorption behavior of anthraquinone-2-carboxylic acid (AQ-2-COOH) on an Ag electrode at different pH values. The obtained results indicate that AQ-2-COOH is adsorbed tilted on the Ag electrode through O-atom of ring carbonyl in a potential range from -0.3 to -0.5 V vs. SCE, but the orientation turns to more tilted orientation with both O-atom of the ring carbonyl and carboxylate group in positive potential region for pH 6.0 and 7.4. However, at pH 10.0, the orientation adopts tilted conformation constantly on the Ag electrode with both O-atom of the anthraquinone ring and carboxylate group in the potential range from -0.3 to -0.5 V vs. SCE or at positive potentials. Moreover, the adsorption behavior of AQ-2-COOH has been further confirmed by AR-XPS on the Ag surface. Proposed reasons for the observed changes in orientation are presented.

  12. The surface reactivity of chalk (biogenic calcite) with hydrophilic and hydrophobic functional groups

    Science.gov (United States)

    Okhrimenko, D. V.; Dalby, K. N.; Skovbjerg, L. L.; Bovet, N.; Christensen, J. H.; Stipp, S. L. S.

    2014-03-01

    surface energies before and after extraction are considered insignificant and we conclude that the sample is not affected by the extraction procedure.The absolute values for the dispersive component of surface energy for North Sea chalks determined here are consistent with data obtained earlier by inverse gas chromatography (IGC) (Skovbjerg et al., 2013). Skovbjerg and colleagues reported values of γd for GS and WS chalk equal to 36.3 and 47.0 mJ/m2. The values reported for the polar components of the surface energy are, however, much lower. This difference is probably associated with the differences in the theoretical background for the two techniques. IGC measures surface interaction with vapours at close to zero coverage, using the Good-van Oss approach (van Oss et al., 1988), whereas the results obtained here are for surfaces fully covered by several layers of adsorbate and use the Owens-Wendt approach (Owens and Wendt, 1969). Our probe molecules (water and ethanol) are also more polar than the probe molecules used for the IGC experiments (dichloromethane and ethyl acetate), which probably leads to overestimation of values for the polar component of the surface energy.The total surface energy of the calcite samples that we obtained is close to reports for marble (Janczuk et al., 1983) and calcite (Goujon and Mutaftschiev, 1976; Okayama et al., 1997). There are, however, considerable differences in the values reported by different groups and in one case (Douillard et al., 1995), values reported are three times higher than our observations. We propose that the history of the samples, thus what is adsorbed on the surfaces, has a great deal to do with the surface tension measured.

  13. Influence of the peroxide group on the surface of titanium dioxide synthesized by the OPM route

    International Nuclear Information System (INIS)

    Santos, Estela Melare Ribeiro dos; Kubo, Andressa Mayumi; Gorup, Luiz Fernando; Francatto, Patricia; Souza Neto, Francisco Nunes de; Leite, Edson Roberto; Longo, Elson; Camargo, Emerson Rodrigues

    2016-01-01

    Full text: In the context of nanotechnology, there is a growing demand for environmentally sustainable solutions and technological innovations that are linked to reducing energy consumption and minimizing waste generation during the synthesis process. The Oxidant Peroxide Method for titanium dioxide synthesis (TiO 2 -OPM) is based on the oxidation of titanium ions to obtain nanometric powders that are highly reactive particles with controlled morphology. This method is easy and advantageous because it uses reagents of low toxicity, without the necessity to operate in inert atmosphere and at high temperatures. In this work, we obtained nanometric powders of TiO 2 -OPM from metallic titanium (TiO 2 -Met), and titanium isopropoxide (TiO 2 -Iso). Separately, the precursors reacts with hydrogen peroxide in ammoniacal medium in order to compare their reactivity by quantifying the peroxo groups on the surface. Scanning electronic microscopy (SEM) images showed nanoparticles of 10nm of both materials. X-ray diffraction (XRD) patterns showed typical structures of crystalline materials with mixture of anatase and rutile phase of titanium dioxide. Raman spectroscopy also cooperated with the XRD patterns showing vibrational modes of the mixture of phases (anatase and rutile) in both materials. Thermogravimetric analysis (TGA) showed that the two materials lost mass, in which in the first stage (80 - 125 deg C) occurred 24% of loss and in the second stage (235-265 deg C) is between 10% - 13%, and is related to the elimination of peroxo groups at the surface due to thermal treatment. Differential scanning calorimetry (DSC) revealed peaks related to exothermic decomposition of the peroxo groups (200 - 250 deg C) that coincided with peak rates of mass loss in the TGA. And the redox titration showed that the surface of the TiO 2 -Met had peroxo groups in 8.6 % w/w and 10.1 % w/w for TiO 2 -Iso, resulting in an increase of peroxo groups on the surface, making the TiO 2 -Iso route

  14. Influence of the peroxide group on the surface of titanium dioxide synthesized by the OPM route

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Estela Melare Ribeiro dos; Kubo, Andressa Mayumi; Gorup, Luiz Fernando; Francatto, Patricia; Souza Neto, Francisco Nunes de; Leite, Edson Roberto; Longo, Elson; Camargo, Emerson Rodrigues, E-mail: estelamelare@yahoo.com.br [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil)

    2016-07-01

    Full text: In the context of nanotechnology, there is a growing demand for environmentally sustainable solutions and technological innovations that are linked to reducing energy consumption and minimizing waste generation during the synthesis process. The Oxidant Peroxide Method for titanium dioxide synthesis (TiO{sub 2}-OPM) is based on the oxidation of titanium ions to obtain nanometric powders that are highly reactive particles with controlled morphology. This method is easy and advantageous because it uses reagents of low toxicity, without the necessity to operate in inert atmosphere and at high temperatures. In this work, we obtained nanometric powders of TiO{sub 2}-OPM from metallic titanium (TiO{sub 2}-Met), and titanium isopropoxide (TiO{sub 2}-Iso). Separately, the precursors reacts with hydrogen peroxide in ammoniacal medium in order to compare their reactivity by quantifying the peroxo groups on the surface. Scanning electronic microscopy (SEM) images showed nanoparticles of 10nm of both materials. X-ray diffraction (XRD) patterns showed typical structures of crystalline materials with mixture of anatase and rutile phase of titanium dioxide. Raman spectroscopy also cooperated with the XRD patterns showing vibrational modes of the mixture of phases (anatase and rutile) in both materials. Thermogravimetric analysis (TGA) showed that the two materials lost mass, in which in the first stage (80 - 125 deg C) occurred 24% of loss and in the second stage (235-265 deg C) is between 10% - 13%, and is related to the elimination of peroxo groups at the surface due to thermal treatment. Differential scanning calorimetry (DSC) revealed peaks related to exothermic decomposition of the peroxo groups (200 - 250 deg C) that coincided with peak rates of mass loss in the TGA. And the redox titration showed that the surface of the TiO{sub 2}-Met had peroxo groups in 8.6 % w/w and 10.1 % w/w for TiO{sub 2}-Iso, resulting in an increase of peroxo groups on the surface, making

  15. Surface layers in the 4A group metals with implanted silicon ions

    International Nuclear Information System (INIS)

    Kovneristyj, Yu.K.; Vavilova, V.V.; Krasnopevtsev, V.V.; Galkin, L.N.; Kudyshev, A.N.; Klechkovskaya, V.V.

    1987-01-01

    A study was made on the change of structure and phase composition of fine near the surface layers of 4A group metals (Hf, Zr, Ti) during ion Si implantation and successive thermal annealing at elevated temperatures. Implantation of Si + ions with 30 or 16 keV energy in Ti, Zr and Hf at room temperature results to amorphization of metal surface layer. The surface hafnium and titanium layer with implanted Si atoms due to interaction with residual atmosphere of oxygen turns during annealing at 870 K to amorphous solid solution of HfO 2m or TiO 2 with Si, preventing further metal oxidation; layers of amorphous alloy are characterized by thermal stability up to 1270 K. Oxidation of the surface amorphous layer in residual oxygen atmosphere and its crystallization in ZrO 2 take place in result of Zr annealing with implanted Si ions at temperature not exceeding 870 K. Similar phenomena are observed in the case of hafnium with implanted oxygen ions or small dose of silicon ions. Thermal stability of amorphous layers produced during ion implantation of Si in Ti, Zr and Hf corresponds to scale resistance of monolithic alloys in Ti-Si, Zr-Si and Hf-Si systems

  16. Documentation for The Group for High Resolution Sea Surface Temperature (GHRSST) data archived at NCEI (NCEI Accession 0123222)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Group for High Resolution Sea Surface Temperature (GHRSST) is an international open group for SST data producers, users, and scientists. It brings together...

  17. CARBOXYLIC ACIDS ELECTROOXIDATION ON SHUNGITE ELECTRODE

    Directory of Open Access Journals (Sweden)

    Oleksandr Davydenko

    2017-03-01

    Full Text Available Purpose: This article discusses the electrochemical method of directional conversion of carboxylic acids, which are the most aggressive hydrocarbons oxidation products back into the corresponding hydrocarbons. Existing methods for the regeneration of waste petroleum oils have significant drawbacks, which include the formation of new hard-reclaimed waste and loss of a significant part of the oil during regeneration. Methods: Electrooxidation processes of carboxylic acid on various electrode materials: platinum, graphite and shungite anodes were studied. Results: Potentiostatic polarization curves with simultaneous measurement of near-electrode solution pH showed differences in the process on these anode materials: dimer yield for Kolbe is decreased under the transition from platinum to shungite. At potentials higher than 2.0 v, carboxylic acid has a higher adsorbability compared to water. Therefore Faraday’s side-process of water oxidation doesn’t almost occur, which contributes to high yield of expected product according to current. Electrolysis of carboxylic acids solutions under controlled potential (2.0 and 2.4 V and chromatographic analysis of the formed products showed that along with the dimeric structures formation for Kolbe reaction, the occurrence of a hydrocarbons mixture takes place, which may be the result of disproportionation of hydrocarbon radicals (alkane and alkene and hydrocarbons of isomeric structure, by further oxidation of the hydrocarbon radical to carbocation and its subsequent transformation into the corresponding saturated and unsaturated isomers. Such statement is not supported by conception of the process of one- and two-electron carboxylic acid oxidation. Discussion: General carboxylic acid oxidation scheme according to one-electron mechanism (dimerization and disproportionation of the radical and two-electron mechanism (formation and carbocation rearrangement is proposed. The formation of hydrocarbons under

  18. Investigating the Interaction of Water Vapour with Aminopropyl Groups on the Surface of Mesoporous Silica Nanoparticles.

    Science.gov (United States)

    Paul, Geo; Musso, Giorgia Elena; Bottinelli, Emanuela; Cossi, Maurizio; Marchese, Leonardo; Berlier, Gloria

    2017-04-05

    The interaction of water molecules with the surface of hybrid silica-based mesoporous materials is studied by 29 Si, 1 H and 13 C solid-state NMR and IR spectroscopy, with the support of ab initio calculations. The surface of aminopropyl-grafted mesoporous silica nanoparticles is studied in the dehydrated state and upon interaction with controlled doses of water vapour. Former investigations described the interactions between aminopropyl and residual SiOH groups; the present study shows the presence of hydrogen-bonded species (SiOH to NH 2 ) and weakly interacting "free" aminopropyl chains with restricted mobility, together with a small amount of protonated NH 3 + groups. The concentration of the last-named species increased upon interaction with water, and this indicates reversible and fast proton exchange from water molecules to a fraction of the amino groups. Herein, this is discussed and explained for the first time, by a combination of experimental and theoretical approaches. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Heparainization of gas plasma-modified polystyrene surfaces and the interactions of these surfaces with proteins studied with surface plasmon resonance

    NARCIS (Netherlands)

    van Delden, C.J.; van Delden, C.J.; Lens, J.P.; Lens, J.P.; Kooyman, R.P.H.; Engbers, G.H.M.; Feijen, Jan

    1997-01-01

    Polystyrene surfaces obtained by spin-coating a solution of polystyrene in toluene on a gold layer were functionalized with carboxylic acid groups by preadsorption of the sodium salt of undecylenic acid, followed by an argon plasma treatment. A conjugate of albumin and heparin (alb-hep) was

  20. Iron carbide on titania surface modified with group VA oxides as Fischer-Tropsch catalysts

    International Nuclear Information System (INIS)

    Wachs, I.E.; Fiato, R.A.; Chersich, C.C.

    1986-01-01

    A catalyst is described comprising iron carbide supported on a surface modified titania wherein the support comprises an oxide of a metal selected form the group consisting of niobium, vanadium, tantalum or mixture thereof supported on the titania wherein at least a portion of the supported oxide of niobium, vanandium, tantalum or mixture is in a non-crystalline form. The amount of the supported oxide ranges from about 0.5 to 25 weight percent metal oxide on the titania support based on the total support composition and the catalyst contains at least about 2 milligrams of iron, calculated as Fe/sub 2/O/sub 3/, per square meter of support surface

  1. Highly Carboxylated Cellulose Nanofibers via Succinic Anhydride Esterification of Wheat Fibers and Facile Mechanical Disintegration.

    Science.gov (United States)

    Sehaqui, H; Kulasinski, K; Pfenninger, N; Zimmermann, T; Tingaut, P

    2017-01-09

    We report herein the preparation of 4-6 nm wide carboxyl-functionalized cellulose nanofibers (CNF) via the esterification of wheat fibers with cyclic anhydrides (maleic, phtalic, and succinic) followed by an energy-efficient mechanical disintegration process. Remarkable results were achieved via succinic anhydride esterification that enabled CNF isolation by a single pass through the microfluidizer yielding a transparent and thick gel. These CNF carry the highest content of carboxyl groups ever reported for native cellulose nanofibers (3.8 mmol g -1 ). Compared to conventional carboxylated cellulose nanofibers prepared via Tempo-mediated oxidation of wheat fibers, the present esterified CNF display a higher molar-mass and a better thermal stability. Moreover, highly carboxylated CNF from succinic anhydride esterification were effectively integrated into paper filters for the removal of lead from aqueous solution and are potentially of interest as carrier of active molecules or as transparent films for packaging, biomedical or electronic applications.

  2. Thermodynamic properties of alkyl 1H-indole carboxylate derivatives: A combined experimental and computational study

    International Nuclear Information System (INIS)

    Carvalho, Tânia M.T.; Amaral, Luísa M.P.F.; Morais, Victor M.F.; Ribeiro da Silva, Maria D.M.C.

    2016-01-01

    Highlights: • Combustion of methyl 1H-indole-3-carboxylate and ethyl 1H-indole-2-carboxylate by static bomb calorimetry. • The Knudsen mass-loss effusion technique was used to measure the vapour pressures of compounds at different temperatures. • Enthalpies of sublimation of methyl 1H-indole-3-carboxylate and ethyl 1H-indole-2-carboxylate. • Gas-phase enthalpies of formation of methyl 1H-indole-3-carboxylate and ethyl 1H-indole-2-carboxylate have been derived. • Gas-phase enthalpies of formation estimated from G3(MP2) calculations. - Abstract: The standard (p"o = 0.1 MPa) molar enthalpies of formation, in the crystalline phase, of methyl 1H-indole-3-carboxylate and ethyl 1H-indole-2-carboxylate, at T = 298.15 K, were derived from measurements of the standard massic energies of combustion using a static bomb combustion calorimeter. The Knudsen effusion technique was used to measure the vapour pressures as a function of the temperature, which allowed determining the standard molar enthalpies of sublimation of these compounds. The standard (p"o = 0.1 MPa) molar enthalpies of formation, in the gaseous phase, at T = 298.15 K, were calculated by combining, for each compound, the standard molar enthalpy of formation, in the crystalline phase, and the standard molar enthalpy of sublimation, yielding −(207.6 ± 3.6) kJ·mol"−"1 and −(234.4 ± 2.4) kJ·mol"−"1, for methyl 1H-indole-3-carboxylate and ethyl 1H-indole-2-carboxylate, respectively. Quantum chemical studies were also conducted, in order to complement the experimental study. The gas-phase enthalpies of formation were estimated from high level ab initio molecular orbital calculations, at the G3(MP2) level, for the compounds studied experimentally, extending the study to the methyl 1H-indole-2-carboxylate and ethyl 1H-indole-3-carboxylate. The results obtained were compared with the experimental data and were also analysed in terms of structural enthalpic group contributions.

  3. Synthesis and fluorescence study of phenylcoumarin/cyanophenylbenzocoumarin-3-carboxylates

    Directory of Open Access Journals (Sweden)

    Hosanagara N. Harishkumar

    2012-01-01

    Full Text Available The absorption and fluorescence spectra of phenylcoumarin and cyanophenylbenzocoumarin-3-carboxylates 6a-f and 9a-e have been investigated in chloroform, acetonitrile and ethanol. The substituting groups with varying electron donating ability such as N,N-diethyl amine and morpholine at 7-position, in phenylcoumarin-3-carboxylate 6a-f exhibits fluorescence at a longer wavelength i.e. 420-460 nm in chloroform and 460-504 nm in acetonitrile. However the morpholine derivatives 6f-j did not show fluorescence in chloroform. In another series of cyanophenylbenzocoumarin-3-carboxylates 9a-e, the compound 9c exhibits fluorescence at 546 nm in ethanol and 256 nm in acetonitrile, and lower emission wavelength i.e. 356 nm in chloroform. Further the compounds 6e , 9b, 9d and 9e exhibited high quantum yield in ethanol i.e., Φ F = 0.79, 0.70, 0.80 and 0.74 respectively compare to Rhodamine B ( Φ F = 0.24 in ethanol.

  4. Operable Unit 3-13, Group 3, Other Surface Soils (Phase II) Field Sampling Plan

    Energy Technology Data Exchange (ETDEWEB)

    G. L. Schwendiman

    2006-07-27

    This Field Sampling Plan describes the Operable Unit 3-13, Group 3, Other Surface Soils, Phase II remediation field sampling activities to be performed at the Idaho Nuclear Technology and Engineering Center located within the Idaho National Laboratory Site. Sampling activities described in this plan support characterization sampling of new sites, real-time soil spectroscopy during excavation, and confirmation sampling that verifies that the remedial action objectives and remediation goals presented in the Final Record of Decision for Idaho Nuclear Technology and Engineering Center, Operable Unit 3-13 have been met.

  5. Molecularly oriented surface relief formation in polymethacrylates comprising N-benzylideneaniline derivative side groups

    Science.gov (United States)

    Kawatsuki, Nobuhiro; Hosoda, Risa; Kondo, Mizuho; Sasaki, Tomoyuki; Ono, Hiroshi

    2014-12-01

    Molecularly oriented surface relief (SR) formation in polymethacrylates with N-benzylideneaniline (NBA) derivative side groups is investigated by holographic exposure using a 325 nm He-Cd laser. Because the NBA moieties show a photoinduced orientation perpendicular to the polarization of light, polarization holography successfully forms a molecularly oriented SR structure in accordance with the polarization distribution that includes p-polarized components. Although intensity holography induces molecular orientation, it does not generate a satisfactory SR structure. In all the holographic modes, the SR depth depends on the direction of the C=N bonds in the NBA moieties and the photoproducts affect the SR formation ability.

  6. The homology groups of moduli spaces on non-classical Klein surfaces

    International Nuclear Information System (INIS)

    Zaw, Myint

    2001-08-01

    We describe the moduli space M-vector±(g,c) of non-classical directed Klein surfaces of genus g=h-c-1 with c≥0 distinguished points as a configuration space B ± (h,c) of classes h-slit pairs in C. Based on this model, we prove that M-vector ± (g,c) is non-orientable for any g and c and we compute the homology groups of the moduli spaces M-vector ± (g,c) for g≤2. (author)

  7. Enhancing the efficiency of lithium intercalation in carbon nanotube bundles using surface functional groups.

    Science.gov (United States)

    Xiao, Shiyan; Zhu, Hong; Wang, Lei; Chen, Liping; Liang, Haojun

    2014-08-14

    The effect of surface functionalization on the ability and kinetics of lithium intercalation in carbon nanotube (CNT) bundles has been studied by comparing the dynamical behaviors of lithium (Li) ions in pristine and -NH2 functionalized CNTs via ab initio molecular dynamics simulations. It was observed that lithium intercalation has been achieved quickly for both the pristine and surface functionalized CNT bundle. Our calculations demonstrated for the first time that CNT functionalization improved the efficiency of lithium intercalation significantly at both low and high Li ion density. Moreover, we found that keeping the nanotubes apart with an appropriate distance and charging the battery at a rational rate were beneficial to achieve a high rate of lithium intercalation. Besides, the calculated adsorption energy curves indicated that the potential wells in the system of -NH2 functionalized CNT were deeper than that of the pristine CNT bundle by 0.74 eV, and a third energy minimum with a value of 2.64 eV existed at the midpoint of the central axis of the nanotube. Thus, it would be more difficult to remove Li ions from the nanotube interior after surface functionalization. The barrier for lithium diffusion in the interior of the nanotube is greatly decreased because of the surface functional groups. Based on these results, we would suggest to "damage" the nanotube by introducing defects at its sidewall in order to improve not only the capacity of surface functionalized CNTs but also the efficiency of lithium intercalation and deintercalation processes. Our results presented here are helpful in understanding the mechanism of lithium intercalation into nanotube bundles, which may potentially be applied in the development of CNT based electrodes.

  8. EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Scientific Opinion on Flavouring Group Evaluation 10, Revision 2 (FGE.10Rev2): Aliphatic primary and secondary saturated and unsaturated alcohols, aldehydes, acetals, carboxylic acids and esters containing

    DEFF Research Database (Denmark)

    Larsen, John Christian; Nørby, Karin Kristiane; Beltoft, Vibe Meister

    The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the European Food Safety Authority was requested to evaluate 61 flavouring substances in the Flavouring Group Evaluation 10, Revision 2, using the Procedure in Commission Regulation (EC) No 1565/2000. None of the sub......The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the European Food Safety Authority was requested to evaluate 61 flavouring substances in the Flavouring Group Evaluation 10, Revision 2, using the Procedure in Commission Regulation (EC) No 1565/2000. None...... of the substances were considered to have genotoxic potential. The substances were evaluated through a stepwise approach (the Procedure) that integrates information on structure-activity relationships, intake from current uses, toxicological threshold of concern, and available data on metabolism and toxicity....... The Panel concluded that the 61 substances do not give rise to safety concerns at their levels of dietary intake, estimated on the basis of the MSDI approach. Besides the safety assessment of these flavouring substances, the specifications for the materials of commerce have also been considered. For four...

  9. An efficient method for the carboxylation of few-wall carbon nanotubes with little damage to their sidewalls

    Energy Technology Data Exchange (ETDEWEB)

    Martín, Olga [Department of Materials Science and Engineering and Chemical Engineering, Universidad Carlos III de Madrid, Av. Universidad 30, 28911 Leganés-Madrid (Spain); Gutierrez, Humberto R. [Department of Physics and Astronomy, 102 Natural Science Building, University of Louisville, Louisville, KY 40292 (United States); Maroto-Valiente, Angel [Departamento de Química Inorgánica y Química Técnica, Facultad de Ciencias, UNED, C/ Senda del Rey 9, 28040 Madrid (Spain); Terrones, Mauricio [Research Center for Exotic Nanocarbons (JST), Shinshu University, Wakasato 4-17-1, Nagano 380-8553 (Japan); Department of Physics, Department of Materials Science and Engineering and Materials Research Institute, The Pennsylvania State University, 104 Davey Lab., University Park, PA 16802-6300 (United States); Blanco, Tamara [Materials and Processes Department, Airbus Operations S.L., Paseo John Lennon s/n, 28906 Getafe-Madrid (Spain); Baselga, Juan, E-mail: jbaselga@ing.uc3m.es [Department of Materials Science and Engineering and Chemical Engineering, Universidad Carlos III de Madrid, Av. Universidad 30, 28911 Leganés-Madrid (Spain)

    2013-07-15

    We report a novel method that is able to efficiently functionalize carbon nanotubes (few-walled: from 1 to 6 layers and multiwalled) with a high yield of carboxyl groups, based on treatments with H{sub 2}O{sub 2} in the presence of UV light. The amount of carboxylic groups was quantified by X-ray photoelectron spectroscopy and back-titration, showing both measurements reasonable agreement. According to the zeta potential values and to the amount of suspended nanotubes, we demonstrate that the method is able to produce uniform and stable suspensions of carbon nanotubes in water. With the aid of scanning and transmission electron microscopy, thermogravimetric analysis, and Raman spectroscopy, we show that the surfaces of the tubes are not damaged by the treatment and that the functionalized tubes have an enhanced reactivity toward oxygen. This route is efficient and could now be used to fabricate polymer composites using few-walled and multiwalled carbon nanotubes. - Highlights: • We report an efficient method for acid functionalization of carbon nanotubes. • The method produces uniform and stable suspensions of carbon nanotubes in water. • The surfaces of the tubes are not damaged by the treatment.

  10. Reflection properties of road surfaces. Contribution to OECD Scientific Expert Group AC4 on Road Surface Characteristics.

    NARCIS (Netherlands)

    Schreuder, D.A.

    1983-01-01

    Photometric characteristics of road surfaces are dealt with. Representation of reflection properties in public lighting; quality criteria of road lighting installations; classification of road surfaces; the relation between reflection characteristics and other properties of road pavements in public

  11. Modified PAMAM dendrimer with 4-carbomethoxypyrrolidone surface groups reveals negligible toxicity against three rodent cell-lines

    DEFF Research Database (Denmark)

    Janaszewska, Anna; Ciolkowski, Michal; Wróbel, Dominika

    2013-01-01

    Modification of the surface groups of dendrimers is one of the methods to improve their biocompatibility. This article presents results of experiments related to the toxicity of a modified polyamidoamine (PAMAM) dendrimer of the fourth generation with 4-carbomethoxypyrrolidone surface groups (PAM...

  12. EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Scientific Opinion on Flavouring Group Evaluation 10, Revision 3 (FGE.10Rev3): Aliphatic primary and secondary saturated and unsaturated alcohols, aldehydes, acetals, carboxylic acids and esters containing

    DEFF Research Database (Denmark)

    Larsen, John Christian; Nørby, Karin Kristiane; Beltoft, Vibe Meister

    The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the European Food Safety Authority was requested to evaluate 63 flavouring substances in the Flavouring Group Evaluation 10, including additional two substances in this Revision 3, using the Procedure in Commission...... threshold of concern, and available data on metabolism and toxicity. The Panel concluded that the 62 substances do not give rise to safety concerns at their levels of dietary intake, estimated on the basis of the MSDI approach. Besides the safety assessment of these flavouring substances, the specifications...... for the materials of commerce have also been considered. For four substances evaluated through the Procedure, the stereoisomeric composition has not been specified sufficiently....

  13. Group velocity measurement from the propagation of the ionization front in a surface-wave-produced plasma

    International Nuclear Information System (INIS)

    Cotrino, J.; Gamero, A.; Sola, A.; Lao, C.

    1989-01-01

    During the first instant, previous to steady-state in a surface-wave-produced plasma, an ionization front advance front the launcher to the plasma column end. The velocity of the ionization front is much slower than the group velocity of the surface wave, this give a reflection of the incident signal on the moving ionization front. In this paper, the authors use this effect to calculate the surface wave group velocity

  14. Functionalized carbon nanotubes containing isocyanate groups

    International Nuclear Information System (INIS)

    Zhao Chungui; Ji Lijun; Liu Huiju; Hu Guangjun; Zhang Shimin; Yang Mingshu; Yang Zhenzhong

    2004-01-01

    Functionalized carbon nanotubes containing isocyanate groups can extend the nanotube chemistry, and may promote their many potential applications such as in polymer composites and coatings. This paper describes a facile method to prepare functionalized carbon nanotubes containing highly reactive isocyanate groups on its surface via the reaction between toluene 2,4-diisocyanate and carboxylated carbon nanotubes. Fourier-transformed infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) confirmed that reactive isocyanate groups were covalently attached to carbon nanotubes. The content of isocyanate groups were determined by chemical titration and thermogravimetric analysis (TGA)

  15. Gold nanoparticles as markers for fluorinated surfaces containing embedded amide groups

    Science.gov (United States)

    Ballarin, Barbara; Barreca, Davide; Bertola, Maurizio; Cristina Cassani, Maria; Carraro, Giorgio; Maccato, Chiara; Mignani, Adriana; Nanni, Daniele; Parise, Chiara; Ranieri, Silvia

    2018-05-01

    Indium tin oxide (ITO) substrates were functionalized with fluoroalkylsilanes (FAS) having formula RFC(O)N(R)(CH2)3Si(OMe)3 (1, R = H, RF = C5F11; 2, R = CH3, RF = C5F11;3, R = H, RF = C3F7) and containing embedded amide moieties between the perfluoroalkyl chain and the syloxanic moiety. Subsequently, Au nanoparticle deposition (AuNP) onto the ITO-FAS functionalized surfaces was carried out by immersion into a solution of citrate-stabilized AuNP. The ITO-FAS and AuNP/ITO-FAS modified systems were characterized by various complementary techniques and compared with AuNP/ITO modified with RF(CH2)2Si(OEt)3 (4, RF = C6F13), free from functional groups between the fluorinated tail and the syloxanic moiety. The results showed that only ITO glasses modified with 1, 2 and 3 displayed an oleophobic, as well as hydrophobic, behaviour and that the AuNP Surface Coverage (SC %) directly depended on the fluoroalkylsilane nature with the following trend: 60% ITO-2 > 16% ITO-3 > 9% ITO-1 > 3% ITO-4. The obtained results revealed that, in organosilane 2, the presence of a methyl group on the amide nitrogen increases the steric hindrance in the rotation around the Nsbnd CO bond, resulting in the co-presence of two stable conformers in comparable amounts. Their co-presence in solution, combined with the lack of intermolecular Nsbnd H⋯OCsbnd N hydrogen bonds among the anchored molecules, has dramatic influences on the functionalized ITO, yielding a disorderedly packed coating able to accommodate a large quantity of AuNP. These results indicate that AuNP can act as excellent probes to evaluate the coating layer quality but, at the same time, it is possible to tune the gold loading on electroactive surfaces depending on the chemical structure of the used fluorinated silane.

  16. Synthesis of carboxyl-capped and bright YVO4:Eu,Bi nanoparticles and their applications in immunochromatographic test strip assay

    International Nuclear Information System (INIS)

    Luo, Min; Sun, Tian-Ying; Wang, Jia-Hong; Yang, Peng; Gan, Liang; Liang, Li-Lei; Yu, Xue-Feng; Gong, Xing-Hou

    2013-01-01

    Graphical abstract: - Highlights: • The morphology and properties of YVO 4 :Eu,Bi nanoparticles were investigated. • YVO 4 :Eu,Bi were coupled with IgG for bioprobes due to their good properties. • YVO 4 :Eu,Bi were applied to immunochromatographic test strip assay. - Abstract: Carboxyl-capped YVO 4 :Eu,Bi nanoparticles with average diameter of ∼10 nm were synthesized via a copolymer of phosphono and carboxylic acid mediated hydrothermal method. Under a 350 nm ultraviolet light excitation, the YVO 4 :Eu,Bi NPs exhibit sharp and bright red emission peaked at 615 nm and with highest quantum yield of ∼43%. Furthermore, the nanoparticles show good water/buffer stability and feasible bioconjugation benefiting from the carboxylic groups on their surface. Based on these kind optical and surface properties of the YVO 4 :Eu,Bi nanoparticles, an immunochromatographic test strip assay for quantitative determination of human IgG was achieved. This protocol can be extended to other rare-earth nanoparticles with the purpose of developing bioprobes for desired applications

  17. Properties of the Carboxylate ion exchange resins

    International Nuclear Information System (INIS)

    Allard, Bert; Dario, Maarten; Boren, Hans; Torstenfelt, Boerje; Puigdomenech, Ignasi; Johansson, Claes

    2002-09-01

    Weakly acidic, carboxylic resin has been selected, together with strong base anion resins, for water purification at the Forsmark 1 and 2 reactors. For the strong (but not the weak) ion exchange resin the Nuclear Power Inspectorate has given permission to dispose the spent resins in the SFR 1 (the Final Repository for Radioactive Operational Waste). This report gives a review of the carboxylic resins and comes to the conclusion that the resins are very stable and that there should not exist any risks for increased leaching of radionuclides from SFR 1 if these resins are disposed (compared to the strong resins)

  18. Interaction of photoactive cis(CO)-trans(I)-Ru-(4,4‧-dicarboxylate-2,2‧-bipyridine)(CO)2I2 with anatase (1 0 1) surface

    Science.gov (United States)

    Haukka, Matti; Hirva, Pipsa

    2002-06-01

    The coordination of cis(CO)-trans(I)-Ru(4,4‧-dicarboxylate-2,2‧-bipyridine)(CO)2I2 on an anatase (1 0 1) surface was investigated using a computational density functional method. The adsorbate is able to interact with the anatase surface by one or two carboxylate substituents of the bipyridine ligand. Three of the studied coordination modes involved a single carboxylate as the binding group, including monodentate (1M), bidentate chelating (1BC) and bidentate bridging (1BB) modes. The possibility of monodentate binding via both carboxylate groups in (2M) was also studied. The results showed that the multidentate binding is clearly preferred over monodentate coordination. The stability of the modes increased in the order 1M, 1BC, 1BB and 2M. The flexibility of the bipyridine ligand was found to be the key factor in the binding via two carboxylate groups.

  19. Effect of carboxylic acid of periodic mesoporous organosilicas on the fructose-to-5-hydroxymethylfurfural conversion in dimethylsulfoxide systems

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, Saikat; Wu, Kevin C.-W., E-mail: hmkao@cc.ncu.edu.tw, E-mail: kevinwu@ntu.edu.tw [Department of Chemical Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 10617, Taiwan (China); Kao, Hsien-Ming, E-mail: hmkao@cc.ncu.edu.tw, E-mail: kevinwu@ntu.edu.tw [Department of Chemistry, National Central University, Chung-Li 32054, Taiwan (China)

    2014-11-01

    This manuscript presents the preparation and catalytic application of highly ordered benzene bridged periodic mesoporous organosilicas (PMOs) functionalized with carboxylic acid (–COOH) group at varied density. The COOH-functionalized PMOs were synthesized by one-step condensation of 1,4-bis (triethoxysilyl) benzene and carboxylic group containing organosilane carboxyethylsilanetriol sodium salt using Brij-76 as the template. The obtained materials were characterized by a mean of methods including powder X-ray diffraction, nitrogen adsorption-desorption, scanning- and transmission electron microscopy, and {sup 13}C solid-state nuclear magnetic resonance measurements. The potentials of the obtained PMO materials with ordered mesopores were examined as solid catalysts for the chemical conversion of fructose to 5-hydroxymethylfurfural (HMF) in an organic solvent. The results showed that COOH-functionalized PMO with 10% COOH loading exhibited best results for the fructose to HMF conversion and selectivity. The high surface area, the adequate density acid functional group, and the strength of the PMO materials contributing to a promising catalytic ability were observed.

  20. Effect of carboxylic acid of periodic mesoporous organosilicas on the fructose-to-5-hydroxymethylfurfural conversion in dimethylsulfoxide systems

    International Nuclear Information System (INIS)

    Dutta, Saikat; Wu, Kevin C.-W.; Kao, Hsien-Ming

    2014-01-01

    This manuscript presents the preparation and catalytic application of highly ordered benzene bridged periodic mesoporous organosilicas (PMOs) functionalized with carboxylic acid (–COOH) group at varied density. The COOH-functionalized PMOs were synthesized by one-step condensation of 1,4-bis (triethoxysilyl) benzene and carboxylic group containing organosilane carboxyethylsilanetriol sodium salt using Brij-76 as the template. The obtained materials were characterized by a mean of methods including powder X-ray diffraction, nitrogen adsorption-desorption, scanning- and transmission electron microscopy, and 13 C solid-state nuclear magnetic resonance measurements. The potentials of the obtained PMO materials with ordered mesopores were examined as solid catalysts for the chemical conversion of fructose to 5-hydroxymethylfurfural (HMF) in an organic solvent. The results showed that COOH-functionalized PMO with 10% COOH loading exhibited best results for the fructose to HMF conversion and selectivity. The high surface area, the adequate density acid functional group, and the strength of the PMO materials contributing to a promising catalytic ability were observed

  1. Carboxylated dithiafulvenes and tetrathiafulvalene vinylogues: synthesis, electronic properties, and complexation with zinc ions

    Directory of Open Access Journals (Sweden)

    Yunfei Wang

    2015-06-01

    Full Text Available A class of carboxyl and carboxylate ester-substituted dithiafulvene (DTF derivatives and tetrathiafulvalene vinylogues (TTFVs has been synthesized and their electronic and electrochemical redox properties were characterized by UV–vis spectroscopic and cyclic voltammetric analyses. The carboxyl-TTFV was applied as a redox-active ligand to complex with Zn(II ions, forming a stable Zn-TTFV coordination polymer. The structural, electrochemical, and thermal properties of the coordination polymer were investigated by infrared spectroscopy, cyclic voltammetry, powder X-ray diffraction, and differential scanning calorimetric analyses. Furthermore, the microscopic porosity and surface area of the Zn-TTFV coordination polymer were measured by nitrogen gas adsorption analysis, showing a BET surface of 148.2 m2 g−1 and an average pore diameter of 10.2 nm.

  2. Counting surface-kernel epimorphisms from a co-compact Fuchsian group to a cyclic group with motivations from string theory and QFT

    Directory of Open Access Journals (Sweden)

    Khodakhast Bibak

    2016-09-01

    Full Text Available Graphs embedded into surfaces have many important applications, in particular, in combinatorics, geometry, and physics. For example, ribbon graphs and their counting is of great interest in string theory and quantum field theory (QFT. Recently, Koch et al. (2013 [12] gave a refined formula for counting ribbon graphs and discussed its applications to several physics problems. An important factor in this formula is the number of surface-kernel epimorphisms from a co-compact Fuchsian group to a cyclic group. The aim of this paper is to give an explicit and practical formula for the number of such epimorphisms. As a consequence, we obtain an ‘equivalent’ form of Harvey's famous theorem on the cyclic groups of automorphisms of compact Riemann surfaces. Our main tool is an explicit formula for the number of solutions of restricted linear congruence recently proved by Bibak et al. using properties of Ramanujan sums and of the finite Fourier transform of arithmetic functions.

  3. Counting surface-kernel epimorphisms from a co-compact Fuchsian group to a cyclic group with motivations from string theory and QFT

    Energy Technology Data Exchange (ETDEWEB)

    Bibak, Khodakhast, E-mail: kbibak@uvic.ca; Kapron, Bruce M., E-mail: bmkapron@uvic.ca; Srinivasan, Venkatesh, E-mail: srinivas@uvic.ca

    2016-09-15

    Graphs embedded into surfaces have many important applications, in particular, in combinatorics, geometry, and physics. For example, ribbon graphs and their counting is of great interest in string theory and quantum field theory (QFT). Recently, Koch et al. (2013) gave a refined formula for counting ribbon graphs and discussed its applications to several physics problems. An important factor in this formula is the number of surface-kernel epimorphisms from a co-compact Fuchsian group to a cyclic group. The aim of this paper is to give an explicit and practical formula for the number of such epimorphisms. As a consequence, we obtain an ‘equivalent’ form of Harvey's famous theorem on the cyclic groups of automorphisms of compact Riemann surfaces. Our main tool is an explicit formula for the number of solutions of restricted linear congruence recently proved by Bibak et al. using properties of Ramanujan sums and of the finite Fourier transform of arithmetic functions.

  4. Effect of surface silanol groups on the deposition of apatite onto silica surfaces: a computer simulation study

    CSIR Research Space (South Africa)

    Mkhonto, D

    2008-01-01

    Full Text Available the surface silicon and oxygen species rearrange to form O–Si–O links. Any dangling silicon and oxygen bonds at the silica surfaces are saturated by coordination to oxygen and calcium atoms in the apatite layer, but the extra reactivity afforded by these under...

  5. Charge-transfer excited state in pyrene-1-carboxylic acids adsorbed on titanium dioxide nanoparticles

    Science.gov (United States)

    Krawczyk, S.; Nawrocka, A.; Zdyb, A.

    2018-06-01

    The electronic structure of excited photosensitizer adsorbed at the surface of a solid is the key factor in the electron transfer processes that underlie the efficiency of dye-sensitized solar cells and photocatalysts. In this work, Stark effect (electroabsorption) spectroscopy has been used to measure the polarizability and dipole moment changes in electronic transitions of pyrene-1-carboxylic (PCA), -acetic (PAA) and -butyric (PBA) acids in ethanol, both free and adsorbed on colloidal TiO2, in glassy ethanol at low temperature. The lack of appreciable increase of dipole moment in the excited state of free and adsorbed PAA and PBA points that two or more single bonds completely prevent the expansion of π-electrons from the aromatic ring towards the carboxylic group, thus excluding the possibility of direct electron injection into TiO2. In free PCA, the pyrene's forbidden S0 → S1 transition has increased intensity, exhibits a long progression in 1400 cm-1 Ag mode and is associated with |Δμ| of 2 D. Adsorption of PCA on TiO2 causes a broadening and red shift of the S0 → S1 absorption band and an increase in dipole moment change on electronic excitation to |Δμ| = 6.5 D. This value increased further to about 15 D when the content of acetic acid in the colloid was changed from 0.2% to 2%, and this effect is ascribed to the surface electric field. The large increase of |Δμ| points that the electric field effect can not only change the energetics of electron transfer from the excited sensitizer into the solid, but can also shift the molecular electronic density, thus directly influencing the electronic coupling factor relevant for electron transfer at the molecule-solid interface.

  6. Surface reactivity measurements as required for grouping and read-across: An advanced FRAS protocol

    Science.gov (United States)

    Gandon, Arnaud; Werle, Kai; Neubauer, Nicole; Wohlleben, Wendel

    2017-06-01

    Oxidative stress is a widely accepted paradigm associated with different adverse outcomes of particulate matter, including nanomaterials. It has frequently been identified in in vitro and in vivo studies and different assays have been developed for this purpose. Here we describe a newly developed multi-dose protocol of the FRAS assay (Ferric Reduction Ability of Serum). The purpose of this SOP is the measurement of the surface reactivity of nanomaterials under physiological conditions. Antioxidative components as present in human blood serum (HBS) serve as reporter molecules. The assay separates the oxidative damage from the read-out of the reporter molecules. The results show significantly enhanced repeatability with better sensitivity towards low reactivity, enabling application of FRAS both to a rough grouping by reactive vs. passive nanomaterials and further to substantiation of read-across by enhanced resolution of the similarity between different nanoforms of the same substance.

  7. Surface reactivity measurements as required for grouping and read-across: An advanced FRAS protocol

    International Nuclear Information System (INIS)

    Gandon, Arnaud; Werle, Kai; Neubauer, Nicole; Wohlleben, Wendel

    2017-01-01

    Oxidative stress is a widely accepted paradigm associated with different adverse outcomes of particulate matter, including nanomaterials. It has frequently been identified in in vitro and in vivo studies and different assays have been developed for this purpose. Here we describe a newly developed multi-dose protocol of the FRAS assay (Ferric Reduction Ability of Serum). The purpose of this SOP is the measurement of the surface reactivity of nanomaterials under physiological conditions. Antioxidative components as present in human blood serum (HBS) serve as reporter molecules. The assay separates the oxidative damage from the read-out of the reporter molecules. The results show significantly enhanced repeatability with better sensitivity towards low reactivity, enabling application of FRAS both to a rough grouping by reactive vs. passive nanomaterials and further to substantiation of read-across by enhanced resolution of the similarity between different nanoforms of the same substance. (paper)

  8. Nitric Acid Dehydration Using Perfluoro Carboxylate and Mixed Sulfonate/Carboxylate Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Ames, Richard L. [Colorado School of Mines, Golden, CO (United States)

    2004-09-01

    Perfluoro ionomer membranes are tetrafluoro ethylene-based materials with microheterogeneous structures consisting of a hydrophobic polymer backbone and a hydrophilic side-chain cluster region. Due to the ionomer cluster morphology, these films exhibit unique transport properties. Recent investigations with perfluoro sulfonate and perfluoro sulfonate/carboxylate composite polymers have demonstrated their value in the dehydration of nitric acid and they show potential as an alternative to conventional, energy intensive unit operations in the concentration of acid feeds. As a result, investigations were conducted to determine the feasibility of using pure perfluoro carboxylate and mixed perfluoro sulfonate/carboxylate films for the dehydration of nitric acid because of the speculation of improved water selectivity of the carboxylate pendant chain. During the first phase of these investigations the effort was focused on generating a thin, solution cast perfluoro carboxylate ionomer film, to evaluate the general, chemical and physical characteristics of the polymer, and to assess the material's aqueous transport performance (flux and nitrate separation efficiencies) in pervaporation and high-pressure environments. Results demonstrated that generating robust solution-cast films was difficult yet a number of membranes survived high trans-membrane pressures up to 700 psig. General characterization of the solution cast product showed reduced ion exchange capacities when compared with thicker, ''as received'' perfluoro carboxylate and similar sulfonate films. Small angle x-ray scattering analysis results suggested that the solution cast carboxylate films contained a small fraction of sulfonate terminated side-chains. Aqueous transport experimentation showed that permeate fluxes for both pure water and nitric acid were approximately two orders of magnitude smaller for the carboxylate solution cast membranes when compared to their sulfonate

  9. Micrometer-sized TPM emulsion droplets with surface-mobile binding groups

    Science.gov (United States)

    van der Wel, Casper; van de Stolpe, Guido L.; Verweij, Ruben W.; Kraft, Daniela J.

    2018-03-01

    Colloids coated with lipid membranes have been widely employed for fundamental studies of lipid membrane processes, biotechnological applications such as drug delivery and biosensing, and more recently, for self-assembly. The latter has been made possible by inserting DNA oligomers with covalently linked hydrophobic anchors into the membrane. The lateral mobility of the DNA linkers on micrometer-sized droplets and solid particles has opened the door to creating structures with unprecedented structural flexibility. Here, we investigate micro-emulsions of TPM (3-(trimethoxysilyl)propyl methacrylate) as a platform for lipid monolayers and further functionalization with proteins and DNA oligonucleotides. TPM droplets can be produced with a narrow size distribution and are polymerizable, thus providing supports for model lipid membranes with controlled size and curvature. With fluorescence recovery after photobleaching, we observed that droplet-attached lipids, NeutrAvidin proteins, as well as DNA oligonucleotides all show mobility on the surface. We explored the assembly of micron-sized particles on TPM-droplets by exploiting either avidin-biotin interactions or double-stranded DNA with complementary single-stranded end groups. While the single molecules are mobile, the particles that are attached to them are not. We propose that this is caused by the heterogeneous nature of emulsified TPM, which forms an oligomer network that limits the collective motion of linkers, but allows the surface mobility of individual molecules.

  10. (2S,4R-4-Fluoropyrrolidinium-2-carboxylate

    Directory of Open Access Journals (Sweden)

    David B. Hobart Jr

    2012-08-01

    Full Text Available The crystal structure of the title compound, C5H8FNO2, at 100 K, displays intermolecular N—H...O hydrogen bonding between the ammonium and carboxylate groups as a result of its zwitterionic nature in the solid state. The five-membered ring adopts an envelope conformation with the C atom at the 3-position as the flap. The compound is of interest with respect to the synthesis and structural properties of synthetic collagens. The absolute structure was determined by comparison with the commercially available material.

  11. Methyl 3-(Quinolin-2-ylindolizine-1-carboxylate

    Directory of Open Access Journals (Sweden)

    Roumaissa Belguedj

    2015-12-01

    Full Text Available A novel compound, methyl 3-(quinolin-2-ylindolizine-1-carboxylate (2 has been synthesized by cycloaddition reaction of 1-(quinolin-2-ylmethylpyridinium ylide (1 with methyl propiolate in presence of sodium hydride in THF. The structure of this compound was established by IR, 1H-NMR, 13C-NMR and MS data

  12. Holomorphic representation of constant mean curvature surfaces in Minkowski space: Consequences of non-compactness in loop group methods

    DEFF Research Database (Denmark)

    Brander, David; Rossman, Wayne; Schmitt, Nicholas

    2010-01-01

    We give an infinite dimensional generalized Weierstrass representation for spacelike constant mean curvature (CMC) surfaces in Minkowski 3-space $\\R^{2,1}$. The formulation is analogous to that given by Dorfmeister, Pedit and Wu for CMC surfaces in Euclidean space, replacing the group $SU_2$ with...

  13. Recovery and esterification of aqueous carboxylates by using CO

    NARCIS (Netherlands)

    Cabrera-Rodríguez, Carlos I.; Paltrinieri, Laura; Smet, De Louis C.P.M.; Wielen, Van Der Luuk A.M.; Straathof, Adrie J.J.

    2017-01-01

    The recovery of carboxylic acids from fermentation broth is one of the main bottlenecks for the industrial production of bio-based esters. This paper proposes an alternative for the recovery of carboxylates produced by fermentations at pH values above the pKa of the carboxylic acid. In this

  14. Production of carboxylic acid and salt co-products

    Science.gov (United States)

    Hanchar, Robert J.; Kleff, Susanne; Guettler, Michael V.

    2014-09-09

    This invention provide processes for producing carboxylic acid product, along with useful salts. The carboxylic acid product that is produced according to this invention is preferably a C.sub.2-C.sub.12 carboxylic acid. Among the salts produced in the process of the invention are ammonium salts.

  15. Soil surface protection by Biocrusts: effects of functional groups on textural properties

    Science.gov (United States)

    Concostrina-Zubiri, Laura; Huber-Sannwald, Elisabeth; Martínez, Isabel; Flores Flores, José Luis; Escudero, Adrián

    2015-04-01

    In drylands, where vegetation cover is commonly scarce, soil surface is prone to wind and water soil erosion, with the subsequent loss of topsoil structure and chemical properties. These processes are even more pronounced in ecosystems subjected to extra erosive forces, such as grasslands and rangelands that support livestock production. However, some of the physiological and functional traits of biocrusts (i.e., complex association of cyanobacteria, lichens, mosses, fungi and soil particles) make them ideal to resist in disturbed environments and at the same time to protect soil surface from mechanical perturbations. In particular, the filaments and exudates of soil cyanobacteria and the rhizines of lichen can bind together soil particles, forming soil aggregates at the soil surface and thus enhancing soil stability. Also, they act as "biological covers" that preserve the most vulnerable soil layer from wind and runoff erosion and raindrop impact, maintaining soil structure and composition. In this work, we evaluated soil textural properties and organic matter content under different functional groups of biocrusts (i.e., cyanobacteria crust, 3 lichen species, 1 moss species) and in bare soil. In order to assess the impact of livestock trampling on soil properties and on Biocrust function, we sampled three sites conforming a disturbance gradient (low, medium and high impact sites) and a long-term livestock exclusion as control site. We found that the presence of biocrusts had little effects on soil textural properties and organic matter content in the control site, while noticeable differences were found between bare soil and soil under biocrusts (e.g., up to 16-37% higher clay content, compared to bare soil and up to 10% higher organic matter content). In addition, we found that depending on morphological traits and grazing regime, the effects of biocrusts changed along the gradient. For example, soil under the lichen Diploschistes diacapsis, with thick thallus

  16. Correction: Synthesis of pyrrolidine-3-carboxylic acid derivatives via asymmetric Michael addition reactions of carboxylate-substituted enones.

    Science.gov (United States)

    Yin, Feng; Garifullina, Ainash; Tanaka, Fujie

    2018-04-25

    Correction for 'Synthesis of pyrrolidine-3-carboxylic acid derivatives via asymmetric Michael addition reactions of carboxylate-substituted enones' by Feng Yin et al., Org. Biomol. Chem., 2017, 15, 6089-6092.

  17. The titration of carboxyl-terminated monolayers revisited: in situ calibrated fourier transform infrared study of well-defined monolayers on silicon.

    Science.gov (United States)

    Aureau, D; Ozanam, F; Allongue, P; Chazalviel, J-N

    2008-09-02

    The acid-base equilibrium at the surface of well-defined mixed carboxyl-terminated/methyl-terminated monolayers grafted on silicon (111) has been investigated using in situ calibrated infrared spectroscopy (attenuated total reflectance (ATR)) in the range of 900-4000 cm (-1). Spectra of surfaces in contact with electrolytes of various pH provide a direct observation of the COOH COO (-) conversion process. Quantitative analysis of the spectra shows that ionization of the carboxyl groups starts around pH 6 and extends over more than 6 pH units: approximately 85% ionization is measured at pH 11 (at higher pH, the layers become damaged). Observations are consistently accounted for by a single acid-base equilibrium and discussed in terms of change in ion solvation at the surface and electrostatic interactions between surface charges. The latter effect, which appears to be the main limitation, is qualitatively accounted for by a simple model taking into account the change in the Helmholtz potential associated with the surface charge. Furthermore, comparison of calculated curves with experimental titration curves of mixed monolayers suggests that acid and alkyl chains are segregated in the monolayer.

  18. Analysis of carboxylate coordination function of the isomeric lanthanide pyridinedicarboxylates by means of vibration spectroscopy

    International Nuclear Information System (INIS)

    Puntus, L.; Zolin, V.; Kudryashova, V.

    2004-01-01

    The investigation of IR spectra of salts of six isomers of pyridinedicarboxylic acid (PDA): 2,3-, 2,4-, 2,5-, 2,6-, 3,4- and 3,5-pyridinedicarboxylic acids, have demonstrated that properties of these salts are dependent on the bonding manner of carboxylate groups and on coordination of heterocyclic nitrogen atom. The most prominent differences in properties and spectra of 2,6- and 3,4-PDA salts are conditioned correspondingly by monodentate and bidentate coordination functions of the carboxylate groups in these compounds. The correlation of the breathing vibration frequency, reflecting the rigidity of the heterocyclic ring, with position of the carboxylate substituents, conditioning intramolecular charge transfer (CT), was postulated and proved by shifts of the breathing vibration frequency dependent on the structure of isomeric ligand

  19. Ion-exclusion chromatography with conductimetric detection of aliphatic carboxylic acids on a weakly acidic cation-exchange resin by elution with benzoic acid-beta-cyclodextrin.

    Science.gov (United States)

    Tanaka, Kazuhiko; Mori, Masanobu; Xu, Qun; Helaleh, Murad I H; Ikedo, Mikaru; Taoda, Hiroshi; Hu, Wenzhi; Hasebe, Kiyoshi; Fritz, James S; Haddad, Paul R

    2003-05-16

    In this study, an aqueous solution consisting of benzoic acid with low background conductivity and beta-cyclodextrin (beta-CD) of hydrophilic nature and the inclusion effect to benzoic acid were used as eluent for the ion-exclusion chromatographic separation of aliphatic carboxylic acids with different pKa values and hydrophobicity on a polymethacrylate-based weakly acidic cation-exchange resin in the H+ form. With increasing concentration of beta-cyclodextrin in the eluent, the retention times of the carboxylic acids decreased due to the increased hydrophilicity of the polymethacrylate-based cation-exchange resin surface from the adsorption of OH groups of beta-cyclodextrin. Moreover, the eluent background conductivity decreased with increasing concentration of beta-cyclodextrin in 1 mM benzoic acid, which could result in higher sensitivity for conductimetric detection. The ion-exclusion chromatographic separation of carboxylic acids with high resolution and sensitivity was accomplished successfully by elution with a 1 mM benzoic acid-10 mM cyclodextrin solution without chemical suppression.

  20. The surface protein HvgA mediates group B streptococcus hypervirulence and meningeal tropism in neonates.

    Science.gov (United States)

    Tazi, Asmaa; Disson, Olivier; Bellais, Samuel; Bouaboud, Abdelouhab; Dmytruk, Nicolas; Dramsi, Shaynoor; Mistou, Michel-Yves; Khun, Huot; Mechler, Charlotte; Tardieux, Isabelle; Trieu-Cuot, Patrick; Lecuit, Marc; Poyart, Claire

    2010-10-25

    Streptococcus agalactiae (group B streptococcus; GBS) is a normal constituent of the intestinal microflora and the major cause of human neonatal meningitis. A single clone, GBS ST-17, is strongly associated with a deadly form of the infection called late-onset disease (LOD), which is characterized by meningitis in infants after the first week of life. The pathophysiology of LOD remains poorly understood, but our epidemiological and histopathological results point to an oral route of infection. Here, we identify a novel ST-17-specific surface-anchored protein that we call hypervirulent GBS adhesin (HvgA), and demonstrate that its expression is required for GBS hypervirulence. GBS strains that express HvgA adhered more efficiently to intestinal epithelial cells, choroid plexus epithelial cells, and microvascular endothelial cells that constitute the blood-brain barrier (BBB), than did strains that do not express HvgA. Heterologous expression of HvgA in nonadhesive bacteria conferred the ability to adhere to intestinal barrier and BBB-constituting cells. In orally inoculated mice, HvgA was required for intestinal colonization and translocation across the intestinal barrier and the BBB, leading to meningitis. In conclusion, HvgA is a critical virulence trait of GBS in the neonatal context and stands as a promising target for the development of novel diagnostic and antibacterial strategies.

  1. The Group for High Resolution Sea Surface Temperature: Past, Present and Future.

    Science.gov (United States)

    Donlon, Craig; Casey, Kenneth; Minnett, Peter; Corlett, Gary

    2014-05-01

    In the last decade, satellite Agencies, science, operational user/producer and Sea Surface Temperature practitioner communities have come together within the Group for High Resolution SST (GHRSST) to create a new framework for generation, delivery and application of improved common format high-resolution (~1-10 km) satellite SST datasets for the benefit of society. The GHRSST data system is a mature, robust, and highly reliable near real time and delayed mode data system known as the GHRSST Regional/Global Task Sharing framework (R/GTS) and has operated in NRT since 2006. It consists of distributed Regional Data Assembly Centers (RDACs) around the world that submit their data to a Global Data Assembly Center (GDAC) maintained at the NASA Jet Propulsion Laboratory Physical Oceanography Distributed Active Archive Center (JPL PO.DAAC), where all the data are available for 30 days. After that they are transferred to the GHRSST Long Term Stewardship and Reanalysis Facility (LTSRF) at the U.S. National Oceanographic Data Center (NODC) for long-term preservation and distribution. The extensive user base includes many operational meteorological services, the scientific community, industry and Government. Since the R/GTS has operated, statistics show over 72,000 users have accessed the R/GTS in NRT, accessing over 100 million files amounting to more than 232 Tb of information. GHRSST has an organisation structure that has both fixed and flexible components allowing it to respond effectively and efficiently to new and emerging challenges. GHRSST has often been cited as a model for other Virtual Communities/Constellations. GHRSST is underpinned by an international Science Team and International Project Office together. Long-standing GHRSST Technical Advisory Groups (TAG) and ad hoc Working Groups (WG) are typically at the "cutting edge" of international SST activities delivering real coordination in space-based Earth observations for societal benefit through the prioritized

  2. On the organization and thermal behavior of functional groups on Ti3C2 MXene surfaces in vacuum

    Science.gov (United States)

    Persson, Ingemar; Näslund, Lars-Åke; Halim, Joseph; Barsoum, Michel W.; Darakchieva, Vanya; Palisaitis, Justinas; Rosen, Johanna; Persson, Per O. Å.

    2018-03-01

    The two-dimensional (2D) MXene Ti3C2T x is functionalized by surface groups (T x ) that determine its surface properties for, e.g. electrochemical applications. The coordination and thermal properties of these surface groups has, to date, not been investigated at the atomic level, despite strong variations in the MXene properties that are predicted from different coordinations and from the identity of the functional groups. To alleviate this deficiency, and to characterize the functionalized surfaces of single MXene sheets, the present investigation combines atomically resolved in situ heating in a scanning transmission electron microscope (STEM) and STEM simulations with temperature-programmed x-ray photoelectron spectroscopy (TP-XPS) in the room temperature to 750 °C range. Using these techniques, we follow the surface group coordination at the atomic level. It is concluded that the F and O atoms compete for the DFT-predicted thermodynamically preferred site and that at room temperature that site is mostly occupied by F. At higher temperatures, F desorbs and is replaced by O. Depending on the O/F ratio, the surface bare MXene is exposed as F desorbs, which enables a route for tailored surface functionalization.

  3. Biocompatibility studies of polyacrylonitrile membranes modified with carboxylated polyetherimide

    Energy Technology Data Exchange (ETDEWEB)

    Senthilkumar, S.; Rajesh, S.; Jayalakshmi, A.; Mohan, D., E-mail: mohantarun@gmail.com

    2013-10-15

    Poly (ether-imide) (PEI) was carboxylated and used as the hydrophilic modification agent for the preparation of polyacrylonitrile (PAN) membranes. Membranes were prepared with different blend compositions of PAN and CPEI by diffusion induced precipitation. The modified membranes were characterized by thermo gravimetric analysis (TGA), mechanical analysis, scanning electron microscopy (SEM) and contact angle measurement to understand the influence of CPEI on the properties of the membranes. The biocompatibility studies exhibited reduced plasma protein adsorption, platelet adhesion and thrombus formation on the modified membrane surface. The complete blood count (CBC) results of CPEI incorporated membranes showed stable CBC values and significant decrease in the complement activation were also observed. In addition to good cytocompatibility, monocytes cultured on these modified membranes exhibited improved functional profiles in 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. Thus it could be concluded that PAN/CPEI membranes with excellent biocompatibility can be useful for hemodialysis. Highlights: • Carboxylated PEI was prepared and utilized as hydrophilic modification agent. • CPEI incorporated into PAN to improved biocompatibility and cyto compatibility • Biocompatibility of membranes was correlated with morphology and hydrophilicity. • Antifouling studies of the PAN/CPEI membranes was studied by BSA as model foulant.

  4. Acid-base properties and the chemical imaging of surface-bound functional groups studied with scanning force microscopy

    NARCIS (Netherlands)

    van der Vegte, E.W.; Hadziioannou, G

    1997-01-01

    In this paper we present a scanning force microscopy (SFM) study on electrostatic and hydrogen-bonding interactions between chemically modified SFM probes and surface functional groups. pH-dependent adhesion force measurements in aqueous media between various ionizable functional groups showed a

  5. Surface functionalisation of polypyrrole films using UV light induced radical activation

    International Nuclear Information System (INIS)

    Lisboa, P.; Gilliland, D.; Ceccone, G.; Valsesia, A.; Rossi, F.

    2006-01-01

    Electrochemically deposited polypyrrole (PPy) films were functionalised with amine or carboxylic function. The functionalisation was done by grafting allylamine or acrylic acid (AAc) using UV light radical activation. The active groups of the surface were quantified by X-ray photoelectron spectroscopy (XPS) after chemical derivatisation with trifluoroethanol (TFE) or 4-trifluoromethylbenzaldehyde (TFBA), respectively. Grafting with AAc completely covered the PPy film introducing high levels of carboxylic function. In the case of allylamine grafting, a saturation point at low amine carbon level was achieved. Further characterisation of the surfaces was done by time of flight secondary ion mass spectroscopy (TOF-SIMS), atomic force microscope (AFM) and scanning electron microscope (SEM)

  6. Surface magnetization of the Ising ferromagnet in semi-infinite cubic lattice: renormalization group approach

    International Nuclear Information System (INIS)

    Chame, A.M.N.; Tsallis, C.

    1988-01-01

    The behaviour of the spontaneous surface and bulk magnetizations as function of the temperature for the Ising ferromagnet in a semi-infinitre cubic lattice for various ratios JS/JB (JS and JB are the surface and bulk coupling constants, respectively), is studied. The extraordinary transition where the surface maintains its magnetization as the bulk disorders, was study, in particular; a discontinuity on the first derivative of the surface magnetization at the bulk transition temperature was found. The criticality of the system (universality classes, critical exponents and amplitudes) is discussed. An unexpected slight lack of monotonicity of the surface magnetization as a function of JS/JB for JS/JB [pt

  7. Registration of cortical surfaces using sulcal landmarks for group analysis of MEG data☆

    Science.gov (United States)

    Joshi, Anand A.; Shattuck, David W.; Thompson, Paul M.; Leahy, Richard M.

    2010-01-01

    We present a method to register individual cortical surfaces to a surface-based brain atlas or canonical template using labeled sulcal curves as landmark constraints. To map one cortex smoothly onto another, we minimize a thin-plate spline energy defined on the surface by solving the associated partial differential equations (PDEs). By using covariant derivatives in solving these PDEs, we compute the bending energy with respect to the intrinsic geometry of the 3D surface rather than evaluating it in the flattened metric of the 2D parameter space. This covariant approach greatly reduces the confounding effects of the surface parameterization on the resulting registration. PMID:20824115

  8. A Capillary Electrochromatographic Microchip Packed with Self-Assembly Colloidal Carboxylic Silica Beads

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, In Sun; Kim, Shin Seon; Park, Jong Man [Konkuk University, Seoul (Korea, Republic of)

    2012-04-15

    An electrochromatographic microchip with carboxyl-group-derivatized mono-disperse silica packing was prepared from the corresponding colloidal silica solution by utilizing capillary action and self-assembly behavior. The silica beads in water were primed by the capillary action toward the ends of cross-patterned microchannel on a cyclic olefinic copolymer (COC) substrate. Slow evaporation of water at the front of packing promoted the self-assembled packing of the beads. After thermally binding a cover plate on the chip substrate, reservoirs for sample solutions were fabricated at the ends of the microchannel. The packing at the entrances of the microchannel was silver coated to fix utilizing an electroless silver-plating technique to prevent the erosion of the packed structure caused by the sudden switching of a high voltage DC power source. The electrochromatographic behavior of the microchip was explored and compared to that of the microchip with bare silica packing in basic borate buffer. Electrophoretic migration of Rhodamine B was dominant in the microchip with the carboxyl-derivatized silica packing that resulted in a migration approximated twice as fast, while the reversible adsorption was dominant in the bare silica-packed microchip. Not only the faster migration rates of the negatively charged FITC-derivatives of amino acids but also the different migration due to the charge interaction at the packing surface were observed. The electrochromatographic characteristics were studied in detail and compared with those of the bare silica packed microchip in terms of the packing material, the separation potential, pH of the running buffer, and also the separation channel length

  9. Carboxylic acid exchangers in analytical chemistry

    International Nuclear Information System (INIS)

    Venkateswarlu, Ch.

    1976-01-01

    The literature on the use of carboxylic acid exchangers in inorganic analytical chemistry is reviewed. It is classified under two heads, based on the ionic form in which the exchanger is employed, viz., the salt form and the acid form. In the salt form, the separations reported in the beginning are mostly carried out in alkaline medium, employing ammonia and its derivatives as complexing agents to hold cations in solution. This was followed by the use of ammonium ion as an eluent from heavy weakly or neutral solutions. There are a few separations reported making use of EDTA as eluent. It appears that separation of some anions from cations can be achieved with greater ease with these exchangers than with sulphonic acid type. Contary to the general belief, carboxylic acid exchangers are used in H + form to achieve some analytical separations of cations of interest. These exchangers exhibit better sorption of some cations in presence of complexing agents containing basic nitrogen as a donor. In fact, a careful study of these exchangers with different matrices might yield really selective exchangers, than the chelating ones known commercially. From the separation cited, carboxylic acid exchangers appear to have greater potentialities in their applications, than what is normally expected. (author)

  10. The stability boundary of group-III transition metal diboride ScB 2 (0 0 0 1) surfaces

    Science.gov (United States)

    Zhao, Hui; Qin, Na

    2012-01-01

    Experimental observations and theoretical investigations exhibit that a group-IV(V) transition metal diboride (0 0 0 1) surface is terminated with a 1 × 1 TM(B) layer. As to a group-III transition metal diboride, we have investigated the stability boundary of ScB2 (0 0 0 1) surfaces using first principles total energy plane-wave pseudopotential method based on density functional theory. The Mulliken charge population analysis shows that Sc atoms in the second layer cannot provide B atoms in the first layer with sufficient electrons to form a complete graphene-like boron layer. We also found that the charge transfer between the first and the second layer for the B-terminated surface is more than that for Sc-terminated surface. It elucidates the reason that the outermost interlayer spacing contract more strongly in the B-terminated surface than in the Sc-terminated surface. The surface energies of both terminated ScB2 (0 0 0 1) surfaces as a function of the chemical potential of B are also calculated to check the relative stability of the two surface structures.

  11. Carboxylic acids in crystallization of macromolecules: learning from successful crystallization experiments.

    Science.gov (United States)

    Offermann, Lesa R; He, John Z; Mank, Nicholas J; Booth, William T; Chruszcz, Maksymilian

    2014-03-01

    The production of macromolecular crystals suitable for structural analysis is one of the most important and limiting steps in the structure determination process. Often, preliminary crystallization trials are performed using hundreds of empirically selected conditions. Carboxylic acids and/or their salts are one of the most popular components of these empirically derived crystallization conditions. Our findings indicate that almost 40 % of entries deposited to the Protein Data Bank (PDB) reporting crystallization conditions contain at least one carboxylic acid. In order to analyze the role of carboxylic acids in macromolecular crystallization, a large-scale analysis of the successful crystallization experiments reported to the PDB was performed. The PDB is currently the largest source of crystallization data, however it is not easily searchable. These complications are due to a combination of a free text format, which is used to capture information on the crystallization experiments, and the inconsistent naming of chemicals used in crystallization experiments. Despite these difficulties, our approach allows for the extraction of over 47,000 crystallization conditions from the PDB. Initially, the selected conditions were investigated to determine which carboxylic acids or their salts are most often present in crystallization solutions. From this group, selected sets of crystallization conditions were analyzed in detail, assessing parameters such as concentration, pH, and precipitant used. Our findings will lead to the design of new crystallization screens focused around carboxylic acids.

  12. Relative binding affinity of carboxylate-, phosphonate-, and bisphosphonate-functionalized gold nanoparticles targeted to damaged bone tissue

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Ryan D. [Rush University Medical Center, Department of Anatomy and Cell Biology (United States); Cole, Lisa E.; Roeder, Ryan K., E-mail: rroeder@nd.edu [University of Notre Dame, Department of Aerospace and Mechanical Engineering Bioengineering Graduate Program (United States)

    2012-10-15

    Functionalized Au NPs have received considerable recent interest for targeting and labeling cells and tissues. Damaged bone tissue can be targeted by functionalizing Au NPs with molecules exhibiting affinity for calcium. Therefore, the relative binding affinity of Au NPs surface functionalized with either carboxylate (l-glutamic acid), phosphonate (2-aminoethylphosphonic acid), or bisphosphonate (alendronate) was investigated for targeted labeling of damaged bone tissue in vitro. Targeted labeling of damaged bone tissue was qualitatively verified by visual observation and backscattered electron microscopy, and quantitatively measured by the surface density of Au NPs using field-emission scanning electron microscopy. The surface density of functionalized Au NPs was significantly greater within damaged tissue compared to undamaged tissue for each functional group. Bisphosphonate-functionalized Au NPs exhibited a greater surface density labeling damaged tissue compared to glutamic acid- and phosphonic acid-functionalized Au NPs, which was consistent with the results of previous work comparing the binding affinity of the same functionalized Au NPs to synthetic hydroxyapatite crystals. Targeted labeling was enabled not only by the functional groups but also by the colloidal stability in solution. Functionalized Au NPs were stabilized by the presence of the functional groups, and were shown to remain well dispersed in ionic (phosphate buffered saline) and serum (fetal bovine serum) solutions for up to 1 week. Therefore, the results of this study suggest that bisphosphonate-functionalized Au NPs have potential for targeted delivery to damaged bone tissue in vitro and provide motivation for in vivo investigation.

  13. Derivatization of carboxylic acids with 4-APEBA for detection by positive-ion LC-ESI-MS(/MS) applied for the analysis of prostanoids and NSAID in urine

    NARCIS (Netherlands)

    Kretschmer, A.; Giera, M.A.; Wijtmans, M.; de Vries, L.; Lingeman, H.; Irth, H.; Niessen, W.M.A.

    2011-01-01

    In order to develop a generic positive ionization ESI LC-MS method for a variety of interesting substance classes, a new derivatization strategy for carboxylic acids was developed. The carboxylic acid group is labeled with the bromine containing 4-APEBA reagent based on carbodiimide chemistry. The

  14. [14C]-radiolabeling of {[trans-(8β)]-6-methyl-1-(1-methylethyl) ergoline-8-carboxylic acid, 4-methoxycyclohexyl ester (Z)-2-buteneidioate (1:1)}

    International Nuclear Information System (INIS)

    Marzoni, G.; Wheeler, W.J.; Garbrecht, W.L.

    1988-01-01

    The 5HT 2 -receptor antagonist, [ 14 C]-labeled brace[trans-(8β)]-6-methyl-1-(1-methylethyl)ergoline-8-carboxylic acid, 4-methoxycyclohexyl ester (Z)-2-butenedioate (1:1)brace (LY281067) was synthesized from unlabeled 6-methyl-1-(1-methylethyl)ergoline-8-carboxylic acid. The [ 14 C] label was introduced into the carboxyl group attached to the 8 position of the ergoline nucleus. This site is stable to metabolism. The synthesis involves removal of an unlabeled carboxyl group and subsequent reinsertion of a [ 14 C]-labeled carboxyl group into the same position. The radiolabel is not introduced until near the end of the synthesis which allows for ease of handling and scale-up of intermediates. (author)

  15. Novel Isoniazid cocrystals with aromatic carboxylic acids: Crystal engineering, spectroscopy and thermochemical investigations

    Science.gov (United States)

    Diniz, Luan F.; Souza, Matheus S.; Carvalho, Paulo S.; da Silva, Cecilia C. P.; D'Vries, Richard F.; Ellena, Javier

    2018-02-01

    Four novel cocrystals of the anti-tuberculosis drug Isoniazid (INH), including two polymorphs, with the aromatic carboxylic acids p-nitrobenzoic (PNBA), p-cyanobenzoic (PCNBA) and p-aminobenzoic (PABA) were rationally designed and synthesized by solvent evaporation. Aiming to explore the possible supramolecular synthons of this API, these cocrystals were fully characterized by X-ray diffraction (SCXRD, PXRD), spectroscopic (FT-IR) and thermal (TGA, DSC, HSM) techniques. The cocrystal formation was found to be mainly driven by the synthons formed by the pyridine and hydrazide moieties. In both INH-PABA polymorphs, the COOH acid groups are H-bonded to pyridine and hydrazide groups giving rise to the acid⋯pyridine and acid⋯hydrazide heterosynthons. In INH-PNBA and INH-PCNBA cocrystals these acid groups are only related to the pyridine moiety. In addition to the structural study, supramolecular and Hirshfeld surface analysis were also performed based on the structural data. The cocrystals were identified from the FT-IR spectra and their thermal behaviors were studied by a combination of DSC, TGA and HSM techniques.

  16. Bienzymatic Acetylcholinesterase and Choline Oxidase Immobilized Biosensor Based on a Phenyl Carboxylic Acid-Grafted Multiwalled Carbon Nanotube

    Directory of Open Access Journals (Sweden)

    So-Ra Lee

    2014-01-01

    Full Text Available Bienzymatic acetylcholinesterase (AChE and choline oxidase (ChOx immobilized biosensor based on a phenyl carboxylic acid-grafted multiwalled carbon nanotube (MWNT modified glass carbon electrode (GCE and carbon-screen printed electrode (SPE was fabricated for acetylcholine detection in human blood samples. Phenyl carboxylic acid-modified MWNT supports were prepared by electrochemical polymerization of 4-carboxyphenyl diazonium salts, which were synthesized by an amine group and sodium nitrite, on the surface of the MWNT-modified GCE and SPE in 0.1 M PBS. The successful fabrication of the AChE-ChOx-immobilized biosensor was confirmed via scanning electron microscopy (SEM, X-ray photoelectron spectroscopy (XPS, electrochemical impedance spectroscopy (EIS, and cyclic voltammetry (CV. The sensing range of the biosensor based on a GCE and SPE was 1.0~10 μM and 10~100 μM, respectively. The interfering effect of 0.1 M L-ascorbic acid, 0.1 M L-cysteine, and 0.1 M uric acid to 0.1 M acetylcholine was 3.00%, 9.00%, and 3.00%, respectively. Acetylcholine in a human blood sample was detected by the AChE-ChOx-immobilized biosensor.

  17. Catalytic transformation of functionalized carboxylic acids using multifunctional rhenium complexes.

    Science.gov (United States)

    Naruto, Masayuki; Agrawal, Santosh; Toda, Katsuaki; Saito, Susumu

    2017-06-13

    Carboxylic acids (CAs) are one of the most ubiquitous and important chemical feedstocks available from biorenewable resources, CO 2 , and the petrochemical industry. Unfortunately, chemoselective catalytic transformations of CH n CO 2 H (n = 1-3) groups into other functionalities remain a significant challenge. Herein, we report rhenium V complexes as extremely effective precatalysts for this purpose. Compared to previously reported heterogeneous and homogeneous catalysts derived from high- or low-valent metals, the present method involves a α-C-H bond functionalization, a hydrogenation, and a hydrogenolysis, which affords functionalized alcohols with a wide substrate scope and high chemoselectivity under relatively mild reaction conditions. The results represent an important step toward a paradigm shift from 'low-valent' to 'high-valent' metal complexes by exploring a new portfolio of selective functional group transformations of highly oxygenated organic substrates, as well as toward the exploitation of CAs as a valuable biorenewable feedstock.

  18. In-situ determination of amine/epoxy and carboxylic/epoxy exothermic heat of reaction on surface of modified carbon nanotubes and structural verification of covalent bond formation

    Science.gov (United States)

    Neves, Juliana C.; de Castro, Vinícius G.; Assis, Ana L. S.; Veiga, Amanda G.; Rocco, Maria Luiza M.; Silva, Glaura G.

    2018-04-01

    An effective nanofiller-matrix interaction is considered crucial to produce enhanced nanocomposites. Nevertheless, there is lack of experiments focused in the direct measurement of possible filler-matrix covalent linkage, which was the main goal of this work for a carbon nanotube (CNT)/epoxy system. CNT were functionalized with oxygenated (ox) functions and further with triethylenetetramine (TETA). An in-situ determination methodology of epoxy-CNTs heat of reaction was developed by Differential Scanning Calorimetry (DSC). Values of -(8.7 ± 0.4) and -(6.0 ± 0.6) J/g were observed for epoxy with CNT-ox and CNT-TETA, respectively. These results confirm the occurrence of covalent bonds for both functionalized CNTs, a very important information due to the literature generally disregard this possibility for oxygenated functions. The higher value obtained for CNT-ox can be attributed to a not complete amidation and to steric impediments in the CNT-TETA structure. The modified CNTs produced by DSC experiments were then characterized by X-Ray Photoelectron Spectroscopy, Transmission Electron Microscopy and Thermogravimetry, which confirmed the covalent linkage. This characterization methodology can be used to verify the occurrence of covalent bonds in various nanocomposites with a quantitative evaluation, providing data for better understanding of the role of CNT functional groups and for tailoring its interface with polymers.

  19. Annotated bibliography for liquid metal surface tensions of groups III-A, IV-A, and V-A metals

    International Nuclear Information System (INIS)

    Murtha, M.J.; Burnet, G.

    1976-04-01

    An annotated bibliography has been prepared which includes summaries of 82 publications dating from 1920 and dealing with the measurement of the surface tensions of Groups III-A, IV-A, and V-A metals in the liquid state. The bibliography is organized by key element investigated, and contains a tabulation of correlations for surface tension as a function of temperature. A brief discussion dealing with variables and methods has been included

  20. Cooperation of phosphates and carboxylates controls calcium oxalate crystallization in ultrafiltered urine.

    Science.gov (United States)

    Grohe, Bernd; Chan, Brian P H; Sørensen, Esben S; Lajoie, Gilles; Goldberg, Harvey A; Hunter, Graeme K

    2011-10-01

    Osteopontin (OPN) is one of a group of proteins found in urine that are believed to limit the formation of kidney stones. In the present study, we investigate the roles of phosphate and carboxylate groups in the OPN-mediated modulation of calcium oxalate (CaOx), the principal mineral phase found in kidney stones. To this end, crystallization was induced by addition of CaOx solution to ultrafiltered human urine containing either human kidney OPN (kOPN; 7 consecutive carboxylates, 8 phosphates) or synthesized peptides corresponding to residues 65-80 (pSHDHMDDDDDDDDDGD; pOPAR) or 220-235 (pSHEpSTEQSDAIDpSAEK; P3) of rat bone OPN. Sequence 65-80 was also synthesized without the phosphate group (OPAR). Effects on calcium oxalate monohydrate (COM) and dihydrate (COD) formation were studied by scanning electron microscopy. We found that controls form large, partly intergrown COM platelets; COD was never observed. Adding any of the polyelectrolytes was sufficient to prevent intergrowth of COM platelets entirely, inhibiting formation of these platelets strongly, and inducing formation of the COD phase. Strongest effects on COM formation were found for pOPAR and OPAR followed by kOPN and then P3, showing that acidity and hydrophilicity are crucial in polyelectrolyte-affected COM crystallization. At higher concentrations, OPAR also inhibited COD formation, while P3, kOPN and, in particular, pOPAR promoted COD, a difference explainable by the variations of carboxylate and phosphate groups present in the molecules. Thus, we conclude that carboxylate groups play a primary role in inhibiting COM formation, but phosphate and carboxylate groups are both important in initiating and promoting COD formation.

  1. Friction Regimes of Water-Lubricated Diamond (111): Role of Interfacial Ether Groups and Tribo-Induced Aromatic Surface Reconstructions

    Science.gov (United States)

    Kuwahara, Takuya; Moras, Gianpietro; Moseler, Michael

    2017-09-01

    Large-scale quantum molecular dynamics of water-lubricated diamond (111) surfaces in sliding contact reveals multiple friction regimes. While water starvation causes amorphization of the tribological interface, small H2O traces are sufficient to preserve crystallinity. This can result in high friction due to cold welding via ether groups or in ultralow friction due to aromatic surface passivation triggered by tribo-induced Pandey reconstruction. At higher water coverage, Grotthuss-type diffusion and H2O dissociation yield dense H /OH surface passivation leading to another ultralow friction regime.

  2. A Method for Absolute Determination of the Surface Areal Density of Functional Groups in Organic Thin Films

    Energy Technology Data Exchange (ETDEWEB)

    Min, Hyegeun; Son, Jin Gyeong; Kim, Jeong Won; Yu, Hyunung; Lee, Tae Geol; Moon, Dae Won [Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of)

    2014-03-15

    To develop a methodology for absolute determination of the surface areal density of functional groups on organic and bio thin films, medium energy ion scattering (MEIS) spectroscopy was utilized to provide references for calibration of X-ray photoelectron spectroscopy (XPS) or Fourier transformation-infrared (FT-IR) intensities. By using the MEIS, XPS, and FT-IR techniques, we were able to analyze the organic thin film of a Ru dye compound (C{sub 58}H{sub 86}O{sub 8}N{sub 8}S{sub 2}Ru), which consists of one Ru atom and various stoichiometric functional groups. From the MEIS analysis, the absolute surface areal density of Ru atoms (or Ru dye molecules) was determined. The surface areal densities of stoichiometric functional groups in the Ru dye compound were used as references for the calibration of XPS and FT-IR intensities for each functional group. The complementary use of MEIS, XPS, and FT-IR to determine the absolute surface areal density of functional groups on organic and bio thin films will be useful for more reliable development of applications based on organic thin films in areas such as flexible displays, solar cells, organic sensors, biomaterials, and biochips.

  3. Enhanced biocompatibility of multi-walled carbon nanotubes by surface modification: Future perspectives for drug delivery system

    Science.gov (United States)

    Anandhi, C. M. S.; Asath, R. Mohamed; Mathavan, T.; Benial, A. Milton Franklin

    2017-05-01

    Surface modification of multi-walled carbon nanotubes (MWCNTs) was carried out by introducing mixture of concentrated sulphuric acid and nitric acid by ultrasonication process. The pristine and surface modified MWCNTs were characterized by X-ray diffraction (XRD), Fourier Transform Infrared (FT-IR), Raman spectroscopy and Scanning electron microscopy (SEM) techniques. FT-IR spectra revealed that the presence of carboxylic acid functional groups on the surface of MWCNTs. The integrated intensity ratio of pristine and surface modified MWCNTs was calculated by Raman spectroscopic analysis. XRD patterns examines the crystallinity of the surface modified MWCNTs. SEM analysis investigates the change in morphology of the surface modified MWCNTs compared with that of pristine, which is due to the attachment of the carboxylic acid functional groups. Surface modified MWCNTs acts as precursors for further functionalization with various biomolecules, which improves the biocompatibility and initiates the implementation of MWCNTs in the field of nanomedicine and targeted drug delivery.

  4. Metal extraction by amides of carboxylic acids

    International Nuclear Information System (INIS)

    Skorovarov, D.I.; Chumakova, G.M.; Rusin, L.I.; Ul'anov, V.S.; Sviridova, R.A.; Sviridov, A.L.

    1988-01-01

    Extraction ability of various amides was studied. Data on extraction of rare earths, vanadium, molybdenum, rhenium, uranium, niobium, tantalum by N,N-dibutyl-amides of acetic, nonanic acids and fatly synthetic acids of C 7 -C 9 fractions are presented. Effect of salting-out agents, inorganic acid concentrations on extraction process was studied. Potential ability of using amides of carboxylic acids for extractional concentration of rare earths as well as for recovery and separation of iron, rhenium, vanadium, molybdenum, uranium, niobium, and tantalum was shown

  5. Characterization and reactivity of sodium aluminoborosilicate glass fiber surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz Rivera, Lymaris, E-mail: luo105@psu.edu [Materials Research Institute, Pennsylvania State University, University Park, PA 16802 (United States); Bakaev, Victor A.; Banerjee, Joy [Materials Research Institute, Pennsylvania State University, University Park, PA 16802 (United States); Mueller, Karl T. [Department of Chemistry, Pennsylvania State University, University Park, PA 16802 (United States); Pantano, Carlo G. [Materials Research Institute, Pennsylvania State University, University Park, PA 16802 (United States); Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

    2016-05-01

    Highlights: • XPS revealed that these fiber surfaces contain sodium carbonate weathering products. • IGC–MS data confirms the products of acetic acid reaction with sodium carbonate. • NMR data shows two closely spaced, but distinct sodium carboxylate peaks. • Acetic acid reacts with both sodium in the glass and sodium in the sodium carbonate. - Abstract: Multicomponent complex oxides, such as sodium aluminoborosilicate glass fibers, are important materials used for thermal insulation in buildings and homes. Although the surface properties of single oxides, such as silica, have been extensively studied, less is known about the distribution of reactive sites at the surface of multicomponent oxides. Here, we investigated the reactivity of sodium aluminoborosilicate glass fiber surfaces for better understanding of their interface chemistry and bonding with acrylic polymers. Acetic acid (with and without a {sup 13}C enrichment) was used as a probe representative of the carboxylic functional groups in many acrylic polymers and adhesives. Inverse gas chromatography coupled to a mass spectrometer (IGC–MS), and solid state nuclear magnetic resonance (NMR), were used to characterize the fiber surface reactions and surface chemical structure. In this way, we discovered that both sodium ions in the glass surface, as well as sodium carbonate salts that formed on the surface due to the intrinsic reactivity of this glass in humid air, are primary sites of interaction with the carboxylic acid. Surface analysis by X-ray photoelectron spectroscopy (XPS) confirmed the presence of sodium carbonates on these surfaces. Computer simulations of the interactions between the reactive sites on the glass fiber surface with acetic acid were performed to evaluate energetically favorable reactions. The adsorption reactions with sodium in the glass structure provide adhesive bonding sites, whereas the reaction with the sodium carbonate consumes the acid to form sodium-carboxylate, H

  6. Rational Design and Synthesis of Carboxylate Gemini Surfactants with an Excellent Aggregate Behavior for Nano-La2O3 Morphology-Controllable Preparation.

    Science.gov (United States)

    Liao, Xueming; Gao, Zhinong; Xia, Yan; Niu, Fei; Zhai, Wenzhong

    2017-04-04

    A series of carboxylate gemini surfactants (CGS, C n -Φ-C n , n = 12, 14, 16, 18) with diphenyl ketone as a spacer group were prepared using a simple and feasible synthetic method. These CGS exhibited an excellent surface activity with extremely low critical micelle concentration (CMC) value (approximately 10 -5 mol/L), good performance in reducing surface tension (nearly 30 mN/m), and the ability of molecular self-assembly into different aggregate morphologies via adjusting the concentrations, which is attributed to the introduction of diphenyl ketone and carboxylic acid ammonium salt in the molecular structure. Moreover, the surface activity and self-assembly ability of CGS were further optimized by tuning the length of the tail chain. These excellent properties imply that CGS can be a soft template to prepare nanomaterials, especially in morphology-controllable synthesis. By adjusting the concentration of one of CGS (C 12 -Φ-C 12 ), nano-La 2 O 3 particles with diverse morphologies were obtained, including spherical shape, bead-chain shape, rod shape, velvet-antler shape, cedar shape, and bowknot shape. This work offers a vital insight into the rational design of template agents for the development of morphology-controllable nanomaterials.

  7. Mixtures of functionalized aromatic groups generated from diazonium chemistry as templates towards bimetallic species supported on carbon electrode surfaces

    International Nuclear Information System (INIS)

    Vilà, Neus; Bélanger, Daniel

    2012-01-01

    Mixtures of 4-sulfophenyl and 4-aminophenyl groups were grafted onto carbon electrodes by electrochemical reduction of their corresponding diazonium cations. Two experimental methodologies were tested in order to control primarily the composition of the binary organic films and subsequently the composition of the bimetallic Cu/Pt layers. The composition of the organic layers was controlled either by changing the ratio of the two components in solution and applying a cathodic potential at which both diazonium cations are electrochemically reduced. The organic layers were characterized by cyclic voltammetry, X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. These binary organic films were subsequently used as templates to load bimetallic species to the carbon surface based on electrostatic interactions of 4-sulfophenyl and 4-aminophenyl groups with Cu 2+ and PtCl 6 2− ionic species dissolved in solution, respectively. The metal complexes, electrostatically bounded to the ionic sites of the grafted groups, were reduced by using NaBH 4 as reducing agent. The amount of Cu was estimated by stripping voltammetry in a sulfuric acid aqueous solution whereas adsorption/desorption of hydrogen was used to quantify the platinum present on the carbon surface. XPS analysis of the metallic surfaces was also performed to confirm the presence of the metals on the electrode surface. The results indicate that the composition of the bimetallic layers is controlled by the ratio of the 4-sulfophenyl and 4-aminophenyl grafted groups.

  8. Critical surface of the quenched bond-diluted cubic model in self-dual lattice: renormalisation group approach

    International Nuclear Information System (INIS)

    Silva, E.P. da; Tsallis, C.

    1991-01-01

    We propose a quite simple real space renormalisation group which enables us to calculate (for the first time as far as we know, and presumably with high precision) the critical surface of the quenched bond-diluted discrete N-vector ferromagnet. (author)

  9. Surface radiological investigations at the 0816 Site, Waste Area Grouping 13, Oak Ridge National Laboratory, Oak Ridge, Tennessee

    International Nuclear Information System (INIS)

    Tiner, P.F.; Uziel, M.S.

    1994-12-01

    A surface radiological investigation was conducted intermittently from July through September 1994 at the 0816 site, located within Waste Area Grouping (WAG) 13. The survey was performed by members of the Measurement Applications and Development Group, Health Sciences Research Division, Oak Ridge National Laboratory (ORNL) at the request of ORNL Site Environmental Restoration Program Facility Management. The purpose of the survey was to ascertain and document the surface radiological condition of the site subsequent to remedial action activities completed in May 1994. The survey was designed to determine whether any residual surface sod contamination in excess of 120 pCi/g 137 Cs (Specified by the Interim Record of Decision) remained at the site

  10. Short Carboxylic Acid–Carboxylate Hydrogen Bonds Can Have Fully Localized Protons

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Jiusheng; Pozharski, Edwin; Wilson, Mark A.

    2017-01-17

    Short hydrogen bonds (H-bonds) have been proposed to play key functional roles in several proteins. The location of the proton in short H-bonds is of central importance, as proton delocalization is a defining feature of low-barrier hydrogen bonds (LBHBs). Experimentally determining proton location in H-bonds is challenging. Here, bond length analysis of atomic (1.15–0.98 Å) resolution X-ray crystal structures of the human protein DJ-1 and its bacterial homologue, YajL, was used to determine the protonation states of H-bonded carboxylic acids. DJ-1 contains a buried, dimer-spanning 2.49 Å H-bond between Glu15 and Asp24 that satisfies standard donor–acceptor distance criteria for a LBHB. Bond length analysis indicates that the proton is localized on Asp24, excluding a LBHB at this location. However, similar analysis of the Escherichia coli homologue YajL shows both residues may be protonated at the H-bonded oxygen atoms, potentially consistent with a LBHB. A Protein Data Bank-wide screen identifies candidate carboxylic acid H-bonds in approximately 14% of proteins, which are typically short [O–O> = 2.542(2) Å]. Chemically similar H-bonds between hydroxylated residues (Ser/Thr/Tyr) and carboxylates show a trend of lengthening O–O distance with increasing H-bond donor pKa. This trend suggests that conventional electronic effects provide an adequate explanation for short, charge-assisted carboxylic acid–carboxylate H-bonds in proteins, without the need to invoke LBHBs in general. This study demonstrates that bond length analysis of atomic resolution X-ray crystal structures provides a useful experimental test of certain candidate LBHBs.

  11. New trends and applications in carboxylation for isotope chemistry.

    Science.gov (United States)

    Bragg, Ryan A; Sardana, Malvika; Artelsmair, Markus; Elmore, Charles S

    2018-05-08

    Carboxylations are an important method for the incorporation of isotopically labeled 14 CO 2 into molecules. This manuscript will review labeled carboxylations since 2010 and will present a perspective on the potential of recent unlabeled methodology for labeled carboxylations. The perspective portion of the manuscript is broken into 3 major sections based on product type, arylcarboxylic acids, benzylcarboxylic acids, and alkyl carboxylic acids, and each of those sections is further subdivided by substrate. © 2018 AstraZeneca. Journal of Labelled Compounds and Radiopharmaceuticals Published by John Wiley & Sons, Ltd.

  12. Study on the surface hydroxyl group on solid breeding materials by ab-initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Tanaka, Satoru; Taniguchi, Masaki [Tokyo Univ. (Japan). Faculty of Engineering

    1996-10-01

    The nature of -OH on the surface of Li{sub 2}O was analyzed with the ab-initio quantum chemical calculation technique. Calculation results showed that the stretching vibration of O-H is affected by the chemical species around the -OH. (author)

  13. Kinetic and equilibrium characterization of uranium(VI) adsorption onto carboxylate-functionalized poly(hydroxyethylmethacrylate)-grafted lignocellulosics.

    Science.gov (United States)

    Anirudhan, T S; Divya, L; Suchithra, P S

    2009-01-01

    This study investigated the feasibility of using a new adsorbent prepared from coconut coir pith, CP (a coir industry-based lignocellulosic residue), for the removal of uranium [U(VI)] from aqueous solutions. The adsorbent (PGCP-COOH) having a carboxylate functional group at the chain end was synthesized by grafting poly(hydroxyethylmethacrylate) onto CP using potassium peroxydisulphate-sodium thiosulphite as a redox initiator and in the presence of N,N'-methylenebisacrylamide as a crosslinking agent. IR spectroscopy results confirm the graft copolymer formation and carboxylate functionalization. XRD studies confirm the decrease of crystallinity in PGCP-COOH compared to CP, and it favors the protrusion of the functional group into the aqueous medium. The thermal stability of the samples was studied using thermogravimetry (TG). Surface charge density of the samples as a function of pH was determined using potentiometric titration. The ability of PGCP-COOH to remove U(VI) from aqueous solutions was assessed using a batch adsorption technique. The maximum adsorption capacity was observed at the pH range 4.0-6.0. Maximum removal of 99.2% was observed for an initial concentration of 25mg/L at pH 6.0 and an adsorbent dose of 2g/L. Equilibrium was achieved in approximately 3h. The experimental kinetic data were analyzed using a first-order kinetic model. The temperature dependence indicates an endothermic process. U(VI) adsorption was found to decrease with an increase in ionic strength due to the formation of outer-sphere surface complexes on PGCP-COOH. Equilibrium data were best modeled by the Langmuir isotherm. The thermodynamic parameters such as DeltaG(0), DeltaH(0) and DeltaS(0) were derived to predict the nature of adsorption. Adsorption experiments were also conducted using a commercial cation exchanger, Ceralite IRC-50, with carboxylate functionality for comparison. Utility of the adsorbent was tested by removing U(VI) from simulated nuclear industry wastewater

  14. Synthesis and characterization of carboxylic cation exchange bio-resin for heavy metal remediation.

    Science.gov (United States)

    Kulkarni, Vihangraj V; Golder, Animes Kumar; Ghosh, Pranab Kumar

    2018-01-05

    A new carboxylic bio-resin was synthesized from raw arecanut husk through mercerization and ethylenediaminetetraacetic dianhydride (EDTAD) carboxylation. The synthesized bio-resin was characterized using thermogravimetric analysis, field emission scanning electron microscopy, proximate & ultimate analyses, mass percent gain/loss, potentiometric titrations, and Fourier transform infrared spectroscopy. Mercerization extracted lignin from the vesicles on the husk and EDTAD was ridged in to, through an acylation reaction in dimethylformamide media. The reaction induced carboxylic groups as high as 0.735mM/g and a cation exchange capacity of 2.01meq/g functionalized mercerized husk (FMH). Potentiometric titration data were fitted to a newly developed single-site proton adsorption model (PAM) that gave pKa of 3.29 and carboxylic groups concentration of 0.741mM/g. FMH showed 99% efficiency in Pb(II) removal from synthetic wastewater (initial concentration 0.157mM), for which the Pb(II) binding constant was 1.73×10 3 L/mol as estimated from modified PAM. The exhaustion capacity was estimated to be 18.7mg/g of FMH. Desorption efficiency of Pb(II) from exhausted FMH was found to be about 97% with 0.1N HCl. The FMH simultaneously removed lead and cadmium below detection limit from a real lead acid battery wastewater along with the removal of Fe, Mg, Ni, and Co. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Solubility studies of inorganic–organic hybrid nanoparticle photoresists with different surface functional groups

    KAUST Repository

    Li, Li

    2016-01-01

    © 2016 The Royal Society of Chemistry. The solubility behavior of Hf and Zr based hybrid nanoparticles with different surface ligands in different concentrations of photoacid generator as potential EUV photoresists was investigated in detail. The nanoparticles regardless of core or ligand chemistry have a hydrodynamic diameter of 2-3 nm and a very narrow size distribution in organic solvents. The Hansen solubility parameters for nanoparticles functionalized with IBA and 2MBA have the highest contribution from the dispersion interaction than those with tDMA and MAA, which show more polar character. The nanoparticles functionalized with unsaturated surface ligands showed more apparent solubility changes after exposure to DUV than those with saturated ones. The solubility differences after exposure are more pronounced for films containing a higher amount of photoacid generator. The work reported here provides material selection criteria and processing strategies for the design of high performance EUV photoresists.

  16. Enhancement of the photocatalytic activity of TiO2 nanoparticles by surface-capping DBS groups

    International Nuclear Information System (INIS)

    Wang Baiqi; Jing Liqiang; Qu Yichun; Li Shudan; Jiang Baojiang; Yang Libin; Xin Baifu; Fu Honggang

    2006-01-01

    TiO 2 nanoparticles capped with sodium dodecylbenzenesulfonate (DBS) are synthesized by a sol-hydrothermal process using tetrabutyl titanate and DBS as raw materials. The effects of surface-capping DBS on the surface photovoltage spectroscopy (SPS), photoluminescence (PL) and photocatalytic performance of TiO 2 nanoparticles are principally investigated together with their relationships. The results show that the surface of TiO 2 nanoparticles can be well capped by DBS groups while the pH value and added DBS amount are controlled at 5.0 and 2% of TiO 2 mass weight, respectively, and the linkage between DBS groups and TiO 2 surfaces is mainly by means of quasi-sulphonate bond. The intensities of SPS and PL spectra of TiO 2 obviously decrease after DBS-capping, while the activity can greatly increase during the photocatalytic degradation of Rhodamine B (RhB) solution, which are mainly attributed to the electron-withdrawing character of the DBS groups. Moreover, the enhancement of photocatalytic activity of DBS-capped TiO 2 is also related to the increase in the capability for adsorbing RhB

  17. Red-shifting and blue-shifting OH groups on metal oxide surfaces - towards a unified picture.

    Science.gov (United States)

    Kebede, Getachew G; Mitev, Pavlin D; Briels, Wim J; Hermansson, Kersti

    2018-05-09

    We analyse the OH vibrational signatures of 56 structurally unique water molecules and 34 structurally unique hydroxide ions in thin water films on MgO(001) and CaO(001), using DFT-generated anharmonic potential energy surfaces. We find that the OH stretching frequencies of intact water molecules on the surface are always downshifted with respect to the gas-phase species while the OH- groups are either upshifted or downshifted. Despite these differences, the main characteristics of the frequency shifts for all three types of surface OH groups (OHw, OsH and OHf) can be accounted for by one unified expression involving the in situ electric field from the surrounding environment, and the gas-phase molecular properties of the vibrating species (H2O or OH-). The origin behind the different red- and blueshift behaviour can be traced back to the fact that the molecular dipole moment of a gas-phase water molecule increases when an OH bond is stretched, but the opposite is true for the hydroxide ion. We propose that familiarity with the relations presented here will help surface scientists in the interpretation of vibrational OH spectra for thin water films on ionic crystal surfaces.

  18. Tailoring surface properties and structure of layered double hydroxides using silanes with different number of functional groups

    International Nuclear Information System (INIS)

    Tao, Qi; He, Hongping; Li, Tian; Frost, Ray L.; Zhang, Dan; He, Zisen

    2014-01-01

    Four silanes, trimethylchlorosilane (TMCS), dimethyldiethoxylsilane (DMDES), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS), were adopted to graft layered double hydroxides (LDH) via an induced hydrolysis silylation method (IHS). Fourier transform infrared spectra (FTIR) and 29 Si MAS nuclear magnetic resonance spectra ( 29 Si MAS NMR) indicated that APTES and TEOS can be grafted onto LDH surfaces via condensation with hydroxyl groups of LDH, while TMCS and DMDES could only be adsorbed on the LDH surface with a small quantity. A combination of X-ray diffraction patterns (XRD) and 29 Si MAS NMR spectra showed that silanes were exclusively present in the external surface and had little influence on the long range order of LDH. The surfactant intercalation experiment indicated that the adsorbed and/or grafted silane could not fix the interlamellar spacing of the LDH. However, they will form crosslink between the particles and affect the further surfactant intercalation in the silylated samples. The replacement of water by ethanol in the tactoids and/or aggregations and the polysiloxane oligomers formed during silylation procedure can dramatically increase the value of BET surface area (S BET ) and total pore volumes (V p ) of the products. - Graphical abstract: The replacement of water by ethanol in the tactoids and aggregations of LDHs, and the polysiloxane oligomers formed during silylation process can dramatically increase the BET surface area (S BET ) and the total pore volume (V p ) of the silylated products. - Highlights: • Silanes with multifunctional groups were grafted onto LDH surface in C 2 H 5 OH medium. • The number of hydrolysable groups in silanes affects the structure of grafted LDH. • Replacement of H 2 O by C 2 H 5 OH in aggregations increases S BET and V p of grafted LDH. • Polysiloxane oligomers contribute to the increase of S BET and V p of grafted LDH

  19. Multifaceted adsorption of α-cyano-4-hydroxycinnamic acid on silver colloidal and island surfaces

    Science.gov (United States)

    Jung, Dawoon; Jeon, Kooknam; Yeo, Juhyun; Hussain, Shafqat; Pang, Yoonsoo

    2017-12-01

    The surface adsorption of organic nitrile compounds on the silver colloidal and island surfaces has been studied using surface-enhanced Raman scattering (SERS). α-Cyano-4-hydroxycinnamic acid (CHCA) with nitrile and carboxyl groups shows various surface adsorption on the silver surfaces. In acidic conditions, the surface adsorption of CHCA via the nitrile group with a more or less tilted geometry to the surface was found. When the solution pH increases, the carboxylate and nitrile groups of deprotonated CHCA participate in the surface adsorption, whereas the molecular plane of CHCA becomes more parallel to the surface. The ν(Ctbnd N) band in SERS of CHCA is the indicator of the surface adsorption geometry. The strongly red-shifted and broadened ν(Ctbnd N) band in SERS represents the surface adsorption via π-electrons of the Ctbnd N bond (side-on geometry; π-coordination). Nitriles adsorbed on the surface via the nonbonding electron pair of the nitrogen atom (end-on geometry; σ-coordination) often cause the blue-shifts and small band broadening in ν(Ctbnd N) in SERS. The surface adsorption geometry of organic nitriles based on many previous experimental results was further confirmed by the surface adsorption of CHCA on the silver island surfaces and dinitrile compounds on the silver colloidal surfaces.

  20. Influence of α-methyl group on molecular aggregation structure and surface physicochemical properties of fluoroalkyl side chain polymers

    International Nuclear Information System (INIS)

    Honda, K; Yamaguchi, H; Takahara, A; Sakata, O; Sasaki, S; Takata, M; Morita, M

    2009-01-01

    Influence of α-methyl group on molecular aggregation states and surface physicochemical properties of poly(fluoroalkyl acrylate)s [PFA-C y , where y is fluoromethylene number in R f group] and poly(fluoroalkykl methacrylate)s [PFMA-C y ] thin films were systematically investigated. Spin-coated PFA-C y and PFMA-C y thin films were characterized by dynamic contact angle measurements and grazing-incidence wide-angle X-ray diffraction (GIWAXD) measurements. GIWAXD data revealed that fluoroalkyl side chains of PFA-C y and PFMA-C y with y≥8 formed regular structures in the surface region as well as bulk one. However, the degree of orientation and ordering of the R f groups of PFMA-C 8 thin films was low. Also, the receding contact angle (θ r ) of PFMA-C 8 thin films was lower than that of PFA-C 8 ones. By annealing treatment, the θ r of PFMA-C 8 was increased. These results suggest that the R f groups of PFMA-C 8 were disordered due to presence of the α-methyl group. The R f groups became ordered to pack closely each other by annealing treatment, so that the water repellency was increased.

  1. Surface-enhanced Raman scattering on molecular self-assembly in nanoparticle-hydrogel composite.

    Science.gov (United States)

    Miljanić, Snezana; Frkanec, Leo; Biljan, Tomislav; Meić, Zlatko; Zinić, Mladen

    2006-10-24

    Surface-enhanced Raman scattering has been applied to study weak intermolecular interactions between small organic gelling molecules involved in the silver nanoparticle-hydrogel composite formation. Assembly and disassembly of the gelator molecules in close vicinity to embedded silver nanoparticles were followed by changes in Raman intensity of the amide II and carboxyl vibrational bands, whereas the strength of the bands related to benzene modes remained constant. This implied that the gelator molecules were strongly attached to the silver particles through the benzene units, while participating in gel structure organization by intermolecular hydrogen bonding between oxalyl amide and carboxyl groups.

  2. Surface characterization of adsorbed asphaltene on a stainless steel surface

    International Nuclear Information System (INIS)

    Abdallah, W.A.; Taylor, S.D.

    2007-01-01

    X-ray photoelectron spectroscopy was used to characterize a single layer of adsorbed asphaltene on a metallic surface. The deposits were created by immersing a stainless steel disc into a dilute asphaltene solution with either toluene or dichloromethane as the solvent, although the toluene solution allowed for better control of the adsorbed asphaltene layer and less atmospheric oxygen contamination. The analyses for C 1s, S 2p 3/2 , N 1s and O 1s photoemission peaks indicated that different functional groups are present in the asphaltene layer including carboxylic, pyrrolic, pyridininc, thiophenic and sulfite, with slight differences in their binding energies

  3. On the one pot syntheses of chromeno[4,3-b]pyridine-3-carboxylate and chromeno[3,4-c]pyridine-3-carboxylate and dihydropyridines

    Energy Technology Data Exchange (ETDEWEB)

    Navarrete-Encina, Patricio A.; Vega-Retter, Christian, E-mail: pnavarre@vtr.ne [Universidad de Chile, Santiago (Chile). Facultad de Ciencias Quimicas y Farmaceuticas. Lab. de Sintesis Organica y Fisicoquimica; Salazar, Ricardo; Perez, Karina; Squella, Juan A.; Nunez-Vergara, Luis J. [Universidad de Chile, Santiago (Chile). Fac. de Ciencias Quimicas y Farmaceuticas. Lab. de Bioelectroquimica

    2010-07-01

    Substituted chromenos, dihydropyridines and pyridines have been important in the syntheses of compounds having interesting pharmacological properties. Therefore, we found of interest to synthesize chromenopyridines and chromeno dihydropyridines (i.e., fused chromeno and dihydropyridine or pyridine rings) to further study their biological activity. Here, we propose one-pot syntheses for substituted ethyl-2,4-dimethyl-5-oxo-5H-chromeno[4,3-b]pyridine-3-carboxylates, ethyl-2,4-dimethyl-5-oxo-5H-chromeno[3,4-c]pyridine-3-carboxylates and their respective 1,4-dihydropyridines based on a modified Hantzsch pyridine synthesis using 2-hydroxyaryl aldehydes, with electron withdrawing and electron donating groups on the phenyl ring, as starting reactants. Sixteen compounds were synthesized by the described method and fully characterized. An average yield of 37% was obtained for the different derivatives. (author)

  4. On the one pot syntheses of chromeno[4,3-b]pyridine-3-carboxylate and chromeno[3,4-c]pyridine-3-carboxylate and dihydropyridines

    International Nuclear Information System (INIS)

    Navarrete-Encina, Patricio A.; Vega-Retter, Christian; Salazar, Ricardo; Perez, Karina; Squella, Juan A.; Nunez-Vergara, Luis J.

    2010-01-01

    Substituted chromenos, dihydropyridines and pyridines have been important in the syntheses of compounds having interesting pharmacological properties. Therefore, we found of interest to synthesize chromenopyridines and chromeno dihydropyridines (i.e., fused chromeno and dihydropyridine or pyridine rings) to further study their biological activity. Here, we propose one-pot syntheses for substituted ethyl-2,4-dimethyl-5-oxo-5H-chromeno[4,3-b]pyridine-3-carboxylates, ethyl-2,4-dimethyl-5-oxo-5H-chromeno[3,4-c]pyridine-3-carboxylates and their respective 1,4-dihydropyridines based on a modified Hantzsch pyridine synthesis using 2-hydroxyaryl aldehydes, with electron withdrawing and electron donating groups on the phenyl ring, as starting reactants. Sixteen compounds were synthesized by the described method and fully characterized. An average yield of 37% was obtained for the different derivatives. (author)

  5. Electronic and magnetic properties of infinite 1D chains of paddlewheel carboxylates M2(COOR)4 (M = Mo, W, Ru, Rh, Ir, Cu)

    KAUST Repository

    Peskov, Maxim; Miao, Xiaohe; Heryadi, Dodi; Eppinger, Jö rg; Schwingenschlö gl, Udo

    2013-01-01

    Dinuclear complexes of transition metals bridged by four carboxylate-groups are examples of stable atomic configurations serving as fundamental building blocks of catalysts and prototypical molecular electronic devices. The electronic structure

  6. Human Cells as Platform to Produce Gamma-Carboxylated Proteins.

    Science.gov (United States)

    de Sousa Bomfim, Aline; de Freitas, Marcela Cristina Corrêa; Covas, Dimas Tadeu; de Sousa Russo, Elisa Maria

    2018-01-01

    The gamma-carboxylated proteins belong to a family of proteins that depend on vitamin K for normal biosynthesis. The major representative gamma-carboxylated proteins are the coagulation system proteins, for example, factor VII, factor IX, factor X, prothrombin, and proteins C, S, and Z. These molecules have harbored posttranslational modifications, such as glycosylation and gamma-carboxylation, and for this reason they need to be produced in mammalian cell lines. Human cells lines have emerged as the most promising alternative to the production of gamma-carboxylated proteins. In this chapter, the methods to generate human cells as a platform to produce gamma-carboxylated proteins, for example the coagulation factors VII and IX, are presented. From the cell line modification up to the vitamin K adaptation of the produced cells is described in the protocols presented in this chapter.

  7. Effects of carboxylic acids on nC60 aggregate formation

    International Nuclear Information System (INIS)

    Chang Xiaojun; Vikesland, Peter J.

    2009-01-01

    The discovery that negatively charged aggregates of C 60 fullerene (nC 60 ) are stable in water has raised concerns regarding the potential environmental and health effects of these aggregates. In this work, we show that nC 60 aggregates produced by extended mixing in the presence of environmentally relevant carboxylic acids (acetic acid, tartaric acid, citric acid) have surface charge and morphologic properties that differ from those produced by extended mixing in water alone. In general, aggregates formed in the presence of these acids have a more negative surface charge and are more homogeneous than those produced in water alone. Carboxylic acid identity, solution pH, and sodium ion concentration, which are all intricately coupled, play an important role in setting the measured surface charge. Comparisons between particle sizes determined by analysis of TEM images and those obtained by dynamic light scattering (DLS) indicate that DLS results require careful evaluation when used to describe nC 60 aggregates. - The effects of carboxylic acids on the formation of nC 60 aggregates are discussed

  8. Behaviour of the surface hydroxide groups of exfoliated kaolinite in the gas phase and during water adsorption.

    Science.gov (United States)

    Táborosi, Attila; Szilágyi, Róbert K

    2016-02-14

    The chemical and physical properties, and thus the reactivity of phylloaluminosilicates can be tailored by intercalation, delamination, and exfoliation processes. In going from the periodic crystalline to the molecular exfoliated phase, surface defects and modifications gain importance as each face of the phylloaluminosilicate comes in direct contact with the external chemical environment. In this work, we extend our earlier studies on the molecular cluster modelling of exfoliated kaolinite sheets by evaluating the positions and orientations of surface hydroxide groups and bridging oxide anions, as the sites of reactivity. The previous focus on the inner chemical environment of a single kaolinite layer is shifted to the surface exposed octahedral aluminium-hydroxide and tetrahedral silicon-oxide sheets. The combination of semi-empirical, ab initio wave function, and density functional calculations unanimously support the amphoteric nature of the surface hydroxide groups with respect to H-bonding donor/acceptor capabilities. To a lesser extent, we observe the same for the bridging oxide anions. This is in contrast to the crystalline phase, which manifests only donor orientation for maintaining an inter-layer H-bond network. These results suggest that both electrophilic and nucleophilic characteristics of the octahedral and tetrahedral sheets need to be considered during intercalation and concomitant exfoliation of the kaolinite sheets.

  9. EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Scientific Opinion on Flavouring Group Evaluation 06, Revision 2 (FGE.06Rev2): Straight- and branched-chain aliphatic unsaturated primary alcohols, aldehydes, carboxylic acids, and esters from chemical groups 1

    DEFF Research Database (Denmark)

    Larsen, John Christian; Nørby, Karin Kristiane; Beltoft, Vibe Meister

    The European Food Safety Authority (EFSA) asked the Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (the Panel) to provide scientific advice to the Commission on the implications for human health of chemically defined flavouring substances used in or on foodstuffs...... in the commercial flavouring material. Forty-six candidate substances are classified into structural class I. The remaining two substances [FL-no: 05.143 and 09.884] are classified into structural class II. Thirty-eight of the flavouring substances in the present group have been reported to occur naturally...... in a wide range of food items. According to the default MSDI approach, the 48 flavouring substances in this group have intakes in Europe from 0.001 to 120 microgram/capita/day, which are below the thresholds of concern value for both structural class I (1800 microgram/person/day) and structural class II...

  10. Kinetic analysis of the reactivity of aliphatic cyclic alcohols and carboxylic acids in the T-for-H exchange reaction

    International Nuclear Information System (INIS)

    Tamura, Kiyoshi; Imaizumi, Hiroshi; Kano, Naoki

    2007-01-01

    In order to quantitatively evaluate the influence of tritium ( 3 He or T) on various functional groups in environment, the hydrogen isotope exchange reaction (T-for-H exchange reaction) between tritium-labeled poly-(vinyl alcohol) and each aliphatic cyclic alcohol (or carboxylic acid) has been dynamically observed in the range of 50 to 90degC. Consequently, the activities of the aliphatic cyclic alcohol and carboxylic acid increased with increasing reaction time. Applying in A''-McKay plot method to the observed data, the rate constants (k) for these materials were obtained. Using the k, the relation between the number of carbon atoms in the ring in each alcohol and the reactivity of the alcohol was quantitatively compared. Then, to clarify the effect of relative atomic charge of O atom (connected with the H atom in the hydroxy (or carboxy) group in the material) on the reactivity of the material, the MOPAC method was used. From both the above-mentioned and the obtained previously, the following nine items were found as to aliphatic cyclic alcohols (and carboxylic acids) in the T-for-H exchange reaction. (1) The reactivity of aliphatic cyclic alcohols (and carboxylic acids) depends on the temperature. (2) The reactivity of the cyclic materials decreases with increasing number of carbon atoms in the ring. (3) The reactivity of the aliphatic cyclic carboxylic acid seems to be smaller than that of aliphatic cyclic alcohol, and be larger than that of aliphatic cyclic amine. (4) For aliphatic cyclic alcohols, correlation exists between k and relative atomic charges of O atom obtained by the MOPAC method, but the tendency for aliphatic cyclic carboxylic acid is not clear. (5) As to having the same number of carbon atoms in each ring, the reactivity of the aliphatic cyclic carboxylic acid including the side chain is smaller than of the aliphatic cyclic carboxylic acid including no side chain. (6) The reactivity of aliphatic cyclic carboxylic acid is larger than that of

  11. Steady nanofluid flow with variable fluid possessions over a linearly extending surface: A Lie group exploration

    Directory of Open Access Journals (Sweden)

    Kalidas Das

    2018-03-01

    Full Text Available The temperament of stream characteristic, heat and mass transfer of MHD forced convective flow over a linearly expanding porous medium has been scrutinized in the progress exploration. The germane possessions of the liquid like viscosity along with thermal conductivity are believed to be variable in nature, directly influenced by the temperature of flow. As soon as gaining the system of leading equations of the stream, Lie symmetric group transformations have been employed to come across the fitting parallel conversions to alter the central PDEs into a suit of ODEs. The renovated system of ODE with appropriate boundary conditions is numerically solved with the assistance of illustrative software MAPLE 17. The consequences of the relevant factors of the system have been exemplified through charts and graphs. An analogous qualified survey has been prepared among present inquiry and subsisting reads and achieved an admirable accord between them. The variable viscosity parameter has more significant effect on nanofluid velocity than regular fluid and temporal profile as well as nanoparticle concentration is also influenced with variable viscosity. Keywords: Nanofluid, Stretching sheet, Variable viscosity, Variable thermal conductivity, Lie symmetry group

  12. Progress in the synthesis and characterization of magnetite nanoparticles with amino groups on the surface

    International Nuclear Information System (INIS)

    Durdureanu-Angheluta, A.; Dascalu, A.; Fifere, A.; Coroaba, A.; Pricop, L.; Chiriac, H.; Tura, V.; Pinteala, M.; Simionescu, B.C.

    2012-01-01

    This manuscript deals with the synthesis of new hydrophilic magnetite particles by employing a two-step method: in the first step magnetite particles with hydrophobic shell formed in presence of oleic acid–oleylamine complex through a synthesis in mass, without solvent, in a mortar with pestle were obtained; while in the second step the hydrophobic shell was interchanged with an aminosilane monomer. The influence of the Fe 2+ /Fe 3+ molar ratio on the dimension of the particles of high importance for their potential applications was carefully investigated. This paper, also presents an alternative method of synthesis of new core-shell magnetite particles and the complete study of their structure and morphology by FT-IR, XPS, TGA, ESEM and TEM techniques. The rheological properties and magnetization analysis of high importance for magnetic particles were also investigated. - Highlights: ► Magnetite particles are superparamagnetic materials. ► Magnetite has significant role in nanotechnology due to surface properties and applicability in physical and chemical processes. ► We used an ecological method of synthesis, a reaction in mass, without solvent, in a mortar with pestle. ► We prepared hydrophilic magnetite particles, precursors for biomedical applications.

  13. Progress in the synthesis and characterization of magnetite nanoparticles with amino groups on the surface

    Energy Technology Data Exchange (ETDEWEB)

    Durdureanu-Angheluta, A.; Dascalu, A.; Fifere, A.; Coroaba, A.; Pricop, L. [Centre of Advanced Research in Bionanoconjugates and Biopolymers, ' ' Petru Poni' ' Institute of Macromolecular Chemistry of Romanian Academy, 41A Aleea Grigore Ghica Voda, 700487 Iasi (Romania); Chiriac, H. [National Institute of Research and Development in Technical Physics, 700050 Iasi (Romania); Tura, V. [Faculty of Physics, ' ' Al. I. Cuza' ' University, B-dul Carol I, no. 11, 700506 Iasi (Romania); Pinteala, M., E-mail: pinteala@icmpp.ro [Centre of Advanced Research in Bionanoconjugates and Biopolymers, ' ' Petru Poni' ' Institute of Macromolecular Chemistry of Romanian Academy, 41A Aleea Grigore Ghica Voda, 700487 Iasi (Romania); Simionescu, B.C. [Centre of Advanced Research in Bionanoconjugates and Biopolymers, ' ' Petru Poni' ' Institute of Macromolecular Chemistry of Romanian Academy, 41A Aleea Grigore Ghica Voda, 700487 Iasi (Romania); Department of Natural and Synthetic Polymers, ' ' Gh. Asachi' ' Technical University of Iasi, 73 Mangeron Blvd, 700050 Iasi (Romania)

    2012-05-15

    This manuscript deals with the synthesis of new hydrophilic magnetite particles by employing a two-step method: in the first step magnetite particles with hydrophobic shell formed in presence of oleic acid-oleylamine complex through a synthesis in mass, without solvent, in a mortar with pestle were obtained; while in the second step the hydrophobic shell was interchanged with an aminosilane monomer. The influence of the Fe{sup 2+}/Fe{sup 3+} molar ratio on the dimension of the particles of high importance for their potential applications was carefully investigated. This paper, also presents an alternative method of synthesis of new core-shell magnetite particles and the complete study of their structure and morphology by FT-IR, XPS, TGA, ESEM and TEM techniques. The rheological properties and magnetization analysis of high importance for magnetic particles were also investigated. - Highlights: Black-Right-Pointing-Pointer Magnetite particles are superparamagnetic materials. Black-Right-Pointing-Pointer Magnetite has significant role in nanotechnology due to surface properties and applicability in physical and chemical processes. Black-Right-Pointing-Pointer We used an ecological method of synthesis, a reaction in mass, without solvent, in a mortar with pestle. Black-Right-Pointing-Pointer We prepared hydrophilic magnetite particles, precursors for biomedical applications.

  14. EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Scientific Opinion on Flavouring Group Evaluation 06, Revision 3 (FGE.06Rev3): Straight- and branched-chain aliphatic unsaturated primary alcohols, aldehydes, carboxylic acids, and esters from chemical groups 1

    DEFF Research Database (Denmark)

    Larsen, John Christian; Nørby, Karin Kristiane; Beltoft, Vibe Meister

    The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the European Food Safety Authority was requested to evaluate 50 flavouring substances in the Flavouring Group Evaluation 6, Revision 3, using the Procedure in Commission Regulation (EC) No 1565/2000. None of the subs......The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the European Food Safety Authority was requested to evaluate 50 flavouring substances in the Flavouring Group Evaluation 6, Revision 3, using the Procedure in Commission Regulation (EC) No 1565/2000. None...... of the substances were considered to have genotoxic potential. The substances were evaluated through a stepwise approach (the Procedure) that integrates information on structure-activity relationships, intake from current uses, toxicological threshold of concern, and available data on metabolism and toxicity...... of these flavouring substances, the specifications for the materials of commerce have also been considered. For one substance [FL-no: 09.938] an identity test is missing and for two substances [FL-no: 05.226 and 09.950] the range of the specific gravity is too wide. Additional, the stereoisomeric mixture has not been...

  15. Structural and thermal properties of carboxylic acid functionalized polythiophenes

    Directory of Open Access Journals (Sweden)

    Ariane de França Mescoloto

    2014-01-01

    Full Text Available Polythiophenes functionalized with polar groups at the end of side-chain have emerged as an alternative method to obtain good compatibility between this class of conjugated polymers and electron acceptor compounds. The aim is to prevent phase segregation and to improve the efficiency of the polythiophene technological devices. However, homopolymers synthesized from thiophene rings with high polar groups at the end of the side-chain, such as hydroxyl and carboxylic acid groups, are poorly soluble in common volatile organic solvents. We report on a systematic preparation of copolymers of 3-hexylthiophene (HT and thiophene-3-acetic acid (TAA, using different feed ratios. The chemical structures of the copolymers were confirmed by FTIR and ¹H-NMR. The TAA content in these copolymers were 33, 38 and 54 mol %. HPSEC results did not show any remarkable correlation with TAA contents in the copolymers. In contrast, the thermal analyses showed a decrease in the thermal stability and an increase in rigidity of their backbones, for the copolymers with high amounts of TAA. The solubility and optical property of copolymers were also related to the TAA contents. Thus, the properties of these copolymers can be modulated by a simple control of feed ratio of TAA in the copolymerization.

  16. Understanding colloidal charge renormilization from surface chemistry : experiment and theory

    OpenAIRE

    Gisler, Thomas; Schulz, S. F.; Borkovec, Michal; Sticher, Hans; Schurtenberger, Peter; D'Aguanno, Bruno; Klein, Rudolf

    1994-01-01

    In this paper we report on the charging behavior of latex particles in aqueous suspensions. We use static light scattering and acid-base titrations as complementary techniques to observe both effective and bare particle charges. Acid-base titrations at various ionic strengths provide the pH dependent charging curves. The surface chemical parameters (dissociation constant of the acidic carboxylic groups, total density of ionizable sites and Stem capacitance) are determined from tits of a Stem ...

  17. Organocatalyzed, Visible-Light Photoredox-Mediated, One-Pot Minisci Reaction Using Carboxylic Acids via N-(Acyloxy)phthalimides.

    Science.gov (United States)

    Sherwood, Trevor C; Li, Ning; Yazdani, Aliza N; Dhar, T G Murali

    2018-03-02

    An improved, one-pot Minisci reaction has been developed using visible light, an organic photocatalyst, and carboxylic acids as radical precursors via the intermediacy of in situ-generated N-(acyloxy)phthalimides. The conditions employed are mild, demonstrate a high degree of functional group tolerance, and do not require a large excess of the carboxylic acid reactant. As a result, this reaction can be applied to drug-like scaffolds and molecules with sensitive functional groups, enabling late-stage functionalization, which is of high interest to medicinal chemistry.

  18. Surface complexation of neptunium (V) onto whole cells and cell componets of Shewanella alga

    Energy Technology Data Exchange (ETDEWEB)

    Reed, Donald Timothy [Los Alamos National Laboratory; Deo, Randhir P [ASU; Rittmann, Bruce E [ASU; Songkasiri, Warinthorn [UNAFFILIATED

    2008-01-01

    We systematically quantified surface complexation of neptunium(V) onto whole cells of Shewanella alga strain BrY and onto cell wall and extracellular polymeric substances (EPS) of S. alga. We first performed acid and base titrations and used the mathematical model FITEQL with constant-capacitance surface-complexation to determine the concentrations and deprotonation constants of specific surface functional groups. Deprotonation constants most likely corresponded to a carboxyl site associated with amino acids (pK{sub a} {approx} 2.4), a carboxyl group not associated with amino acids (pK{sub a} {approx} 5), a phosphoryl site (pK{sub a} {approx} 7.2), and an amine site (pK{sub a} > 10). We then carried out batch sorption experiments with Np(V) and each of the S. alga components at different pHs. Results show that solution pH influenced the speciation of Np(V) and each of the surface functional groups. We used the speciation sub-model of the biogeochemical model CCBATCH to compute the stability constants for Np(V) complexation to each surface functional group. The stability constants were similar for each functional group on S. alga bacterial whole cells, cell walls, and EPS, and they explain the complicated sorption patterns when they are combined with the aqueous-phase speciation of Np(V). For pH < 8, NpO{sub 2}{sup +} was the dominant form of Np(V), and its log K values for the low-pK{sub a} carboxyl, other carboxyl, and phosphoryl groups were 1.75, 1.75, and 2.5 to 3.1, respectively. For pH greater than 8, the key surface ligand was amine >XNH3+, which complexed with NpO{sub 2}(CO{sub 3}){sub 3}{sup 5-}. The log K for NpO{sub 2}(CO{sub 3}){sub 3}{sup 5-} complexed onto the amine groups was 3.1 to 3.6. All of the log K values are similar to those of Np(V) complexes with aqueous carboxyl and N-containing carboxyl ligands. These results point towards the important role of surface complexation in defining key actinide-microbiological interactions in the subsurface.

  19. DFT Study of Binding and Electron Transfer from a Metal-Free Dye with Carboxyl, Hydroxyl, and Sulfonic Anchors to a Titanium Dioxide Nanocluster

    Directory of Open Access Journals (Sweden)

    Corneliu I. Oprea

    2013-01-01

    Full Text Available We report results of density functional theory (DFT calculations of a metal-free dye, 5-(4-sulfophenylazosalicylic acid disodium salt, known as Mordant Yellow 10 (MY-10, used as sensitizer for TiO2 dye-sensitized solar cells (DSSCs. Given the need to better understand the behavior of the dyes adsorbed on the TiO2 nanoparticle, we studied various single and double deprotonated forms of the dye bound to a TiO2 cluster, taking advantage of the presence of the carboxyl, hydroxyl, and sulfonic groups as possible anchors. We discuss various binding configurations to the TiO2 substrate and the charge transfer from the pigment to the oxide by means of DFT calculations. In agreement with other reports, we find that the carboxyl group tends to bind in bidentate bridging configurations. The salicylate uses both the carboxyl and hydroxyl substituent groups for either a tridentate binding to adjacent Ti(IV ions or a bidentate Ti-O binding together with an O-H-O binding, due to the rotation of the carboxyl group out of the plane of the dye. The sulfonic group prefers a tridentate binding. We analyze the propensity for electron transfer of the various dyes and find that for MY-10, as a function of the anchor group, the DSSC performance decreases in the order hydroxyl + carboxyl > carboxyl > sulfonate.

  20. Synthesis of 2-phenyl- and 2,3-diphenyl-quinolin-4-carboxylic acid derivatives

    International Nuclear Information System (INIS)

    Elhadi, S. A.

    2004-09-01

    Quinolin derivatives are a group of compounds known to possess a wide range of biological activities. The chemistry of quinolines together with their corresponding aldehydes were dealt with in chapter one of this study. Special emphasis was given to the chemistry of benzaldehyde. Twenty five 2-phenyl- and 2,3-diphenyl-quinolin-4-carboxylic acid derivatives together with their corresponding intermediates were prepared in this work. Basically, the synthetic design of these compounds arise from the appropriate disconnections of the target 2-phenyl and 2,3-diphenyl-quinolin-4-carboxylic acids. The retro synthesis analysis of these compounds reveals pyruvic acid, aromatic amine and benzaldehyde or phenyl pyruvic acid, aromatic amine and benzaldehyde as possible logical precursors for 2-phenyl-and 2,3-diphenyl- quinoline-4-carboxylic acids respectively. The purity and identities of the synthesized compounds were elucidated through chromatographic and spectroscopic techniques. The compounds were heavily subjected to spectroscopic analysis (UV, IR, GC/MS, 1 H-and 13 C- NMR). The appropriate disconnections and the mechanisms of the corresponding reactions were given and discussed in chapter three. The spectral data were interpreted and correlated with the target structures. The prepared 2-phenyl- and 2,3-diphenyl-quinoline-4-carboxylic acid derivatives were screened for their antibacterial activity. The compounds were tested against the standard bacterial organisms B. subtilis, S. aureus, E. coli and P. vulgaris. Some of these compounds were devoid of antibacterial activity against S. aureus and P. vulgaris, while others showed moderate activity. All of the tested compounds showed an activity against B. subtilis and E. coli. 2,3-diphenyl -6-sulphanilamide-quinolin-4-carboxylic acid showed the highest activity against the four standard tested organisms.(Author)

  1. Synthesis of 2-phenyl- and 2,3-diphenyl-quinolin-4-carboxylic acid derivatives

    Energy Technology Data Exchange (ETDEWEB)

    Elhadi, S A [Department of Chemistry, Faculty of Education, University of Khartoum, Khartoum (Sudan)

    2004-09-01

    Quinolin derivatives are a group of compounds known to possess a wide range of biological activities. The chemistry of quinolines together with their corresponding aldehydes were dealt with in chapter one of this study. Special emphasis was given to the chemistry of benzaldehyde. Twenty five 2-phenyl- and 2,3-diphenyl-quinolin-4-carboxylic acid derivatives together with their corresponding intermediates were prepared in this work. Basically, the synthetic design of these compounds arise from the appropriate disconnections of the target 2-phenyl and 2,3-diphenyl-quinolin-4-carboxylic acids. The retro synthesis analysis of these compounds reveals pyruvic acid, aromatic amine and benzaldehyde or phenyl pyruvic acid, aromatic amine and benzaldehyde as possible logical precursors for 2-phenyl-and 2,3-diphenyl- quinoline-4-carboxylic acids respectively. The purity and identities of the synthesized compounds were elucidated through chromatographic and spectroscopic techniques. The compounds were heavily subjected to spectroscopic analysis (UV, IR, GC/MS, {sup 1}H-and {sup 13}C- NMR). The appropriate disconnections and the mechanisms of the corresponding reactions were given and discussed in chapter three. The spectral data were interpreted and correlated with the target structures. The prepared 2-phenyl- and 2,3-diphenyl-quinoline-4-carboxylic acid derivatives were screened for their antibacterial activity. The compounds were tested against the standard bacterial organisms B. subtilis, S. aureus, E. coli and P. vulgaris. Some of these compounds were devoid of antibacterial activity against S. aureus and P. vulgaris, while others showed moderate activity. All of the tested compounds showed an activity against B. subtilis and E. coli. 2,3-diphenyl -6-sulphanilamide-quinolin-4-carboxylic acid showed the highest activity against the four standard tested organisms.(Author)

  2. Tailoring surface properties and structure of layered double hydroxides using silanes with different number of functional groups

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Qi [Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, Brisbane, Queensland 4001 (Australia); He, Hongping, E-mail: hehp@gig.ac.cn [Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, Brisbane, Queensland 4001 (Australia); Li, Tian [Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); University of Chinese, Academy of Sciences, Beijing 100039 (China); Frost, Ray L. [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, Brisbane, Queensland 4001 (Australia); Zhang, Dan; He, Zisen [Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 (China); University of Chinese, Academy of Sciences, Beijing 100039 (China)

    2014-05-01

    Four silanes, trimethylchlorosilane (TMCS), dimethyldiethoxylsilane (DMDES), 3-aminopropyltriethoxysilane (APTES) and tetraethoxysilane (TEOS), were adopted to graft layered double hydroxides (LDH) via an induced hydrolysis silylation method (IHS). Fourier transform infrared spectra (FTIR) and {sup 29}Si MAS nuclear magnetic resonance spectra ({sup 29}Si MAS NMR) indicated that APTES and TEOS can be grafted onto LDH surfaces via condensation with hydroxyl groups of LDH, while TMCS and DMDES could only be adsorbed on the LDH surface with a small quantity. A combination of X-ray diffraction patterns (XRD) and {sup 29}Si MAS NMR spectra showed that silanes were exclusively present in the external surface and had little influence on the long range order of LDH. The surfactant intercalation experiment indicated that the adsorbed and/or grafted silane could not fix the interlamellar spacing of the LDH. However, they will form crosslink between the particles and affect the further surfactant intercalation in the silylated samples. The replacement of water by ethanol in the tactoids and/or aggregations and the polysiloxane oligomers formed during silylation procedure can dramatically increase the value of BET surface area (S{sub BET}) and total pore volumes (V{sub p}) of the products. - Graphical abstract: The replacement of water by ethanol in the tactoids and aggregations of LDHs, and the polysiloxane oligomers formed during silylation process can dramatically increase the BET surface area (S{sub BET}) and the total pore volume (V{sub p}) of the silylated products. - Highlights: • Silanes with multifunctional groups were grafted onto LDH surface in C{sub 2}H{sub 5}OH medium. • The number of hydrolysable groups in silanes affects the structure of grafted LDH. • Replacement of H{sub 2}O by C{sub 2}H{sub 5}OH in aggregations increases S{sub BET} and V{sub p} of grafted LDH. • Polysiloxane oligomers contribute to the increase of S{sub BET} and V{sub p} of grafted LDH.

  3. Redshift or adduct stabilization -- a computational study of hydrogen bonding in adducts of protonated carboxylic acids

    DEFF Research Database (Denmark)

    Olesen, Solveig Gaarn; Hammerum, Steen

    2009-01-01

    It is generally expected that the hydrogen bond strength in a D-H-A adduct is predicted by the difference between the proton affinities of D and A, measured by the adduct stabilization, and demonstrated by the IR redshift of the D-H bond stretching vibrational frequency. These criteria do...... not always yield consistent predictions, as illustrated by the hydrogen bonds formed by the E and Z OH groups of protonated carboxylic acids. The delta-PA and the stabilization of a series of hydrogen bonded adducts indicate that the E OH group forms the stronger hydrogen bonds, whereas the bond length...... carboxylic acids are different. The OH bond length and IR redshift afford the better measure of hydrogen bond strength....

  4. Alpha-bungarotoxin binding to target cell in a developing visual system by carboxylated nanodiamond

    International Nuclear Information System (INIS)

    Liu, K-K; Chen, P-Y; Lee, Tony J F; Chao, J-I; Chen, M-F; Cheng, C-L; Chang, C-C; Ho, Y-P

    2008-01-01

    Biological molecules conjugating with nanoparticles are valuable for applications including bio-imaging, bio-detection, and bio-sensing. Nanometer-sized diamond particles have excellent electronic and chemical properties for bio-conjugation. In this study, we manipulated the carboxyl group produced on the surface of nanodiamond (carboxylated nanodiamond, cND) for conjugating with alpha-bungarotoxin (α-BTX), a neurotoxin derived from Bungarus multicinctus with specific blockade of alpha7-nicotinic acetylcholine receptor (α7-nAChR). The electrostatic binding of cND-α-BTX was mediated by the negative charge of the cND and the positive charge of the α-BTX in physiological pH conditions. Sodium dodecyl sulfate-polyacrylamide gel analysis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI/TOF-MS) spectra displayed that α-BTX proteins were conjugated with cND particles via non-covalent bindings. The green fluorescence of the cND particles combining with the red fluorescence of tetramethylrhodamine-labeled α-BTX presented a yellow color at the same location, which indicated that α-BTX proteins were conjugated with cND particles. Xenopus laevis's oocytes expressed the human α7-nAChR proteins by microinjection with α7-nAChR mRNA. The cND-α-BTX complexes were bound to α7-nAChR locating on the cell membrane of oocytes and human lung A549 cancer cells analyzed by laser scanning confocal microscopy. The choline-evoked α7-nAChR-mediated inward currents of the oocytes were blocked by cND-α-BTX complexes in a concentration-dependent manner using two-electrode voltage-clamp recording. Furthermore, the fluorescence intensity of cND-α-BTX binding on A549 cells could be quantified by flow cytometry. These results indicate that cND-conjugated α-BTX still preserves its biological activity in blocking the function of α7-nAChR, and provide a visual system showing the binding of α-BTX to α7-nAChR

  5. Alpha-bungarotoxin binding to target cell in a developing visual system by carboxylated nanodiamond

    Energy Technology Data Exchange (ETDEWEB)

    Liu, K-K; Chen, P-Y; Lee, Tony J F; Chao, J-I [Institute of Pharmacology and Toxicology, Tzu Chi University, Hualien 970, Taiwan (China); Chen, M-F [Neuro-Medical Scientific Center, Tzu Chi General Hospital, Hualien 970, Taiwan (China); Cheng, C-L [Department of Physics, National Dong Hwa University, Hualien 974, Taiwan (China); Chang, C-C [Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu 300, Taiwan (China); Ho, Y-P [Department of Chemistry, National Dong Hwa University, Hualien 974, Taiwan (China)], E-mail: chaoji@mail.tcu.edu.tw

    2008-05-21

    Biological molecules conjugating with nanoparticles are valuable for applications including bio-imaging, bio-detection, and bio-sensing. Nanometer-sized diamond particles have excellent electronic and chemical properties for bio-conjugation. In this study, we manipulated the carboxyl group produced on the surface of nanodiamond (carboxylated nanodiamond, cND) for conjugating with alpha-bungarotoxin ({alpha}-BTX), a neurotoxin derived from Bungarus multicinctus with specific blockade of alpha7-nicotinic acetylcholine receptor ({alpha}7-nAChR). The electrostatic binding of cND-{alpha}-BTX was mediated by the negative charge of the cND and the positive charge of the {alpha}-BTX in physiological pH conditions. Sodium dodecyl sulfate-polyacrylamide gel analysis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI/TOF-MS) spectra displayed that {alpha}-BTX proteins were conjugated with cND particles via non-covalent bindings. The green fluorescence of the cND particles combining with the red fluorescence of tetramethylrhodamine-labeled {alpha}-BTX presented a yellow color at the same location, which indicated that {alpha}-BTX proteins were conjugated with cND particles. Xenopus laevis's oocytes expressed the human {alpha}7-nAChR proteins by microinjection with {alpha}7-nAChR mRNA. The cND-{alpha}-BTX complexes were bound to {alpha}7-nAChR locating on the cell membrane of oocytes and human lung A549 cancer cells analyzed by laser scanning confocal microscopy. The choline-evoked {alpha}7-nAChR-mediated inward currents of the oocytes were blocked by cND-{alpha}-BTX complexes in a concentration-dependent manner using two-electrode voltage-clamp recording. Furthermore, the fluorescence intensity of cND-{alpha}-BTX binding on A549 cells could be quantified by flow cytometry. These results indicate that cND-conjugated {alpha}-BTX still preserves its biological activity in blocking the function of {alpha}7-nAChR, and provide a visual

  6. One-step hydrothermal synthesis of carboxyl-functionalized upconversion phosphors for bioapplications.

    Science.gov (United States)

    Yang, Jianping; Shen, Dengke; Li, Xiaomin; Li, Wei; Fang, Yin; Wei, Yong; Yao, Chi; Tu, Bo; Zhang, Fan; Zhao, Dongyuan

    2012-10-22

    In this paper, we report a facile one-step hydrothermal method to synthesize phase-, size-, and shape-controlled carboxyl-functionalized rare-earth fluorescence upconversion phosphors by using a small-molecule binary acid, such as malonic acid, oxalic acid, succinic acid, or tartaric acid as capping agent. The crystals, from nano- to microstructures with diverse shapes that include nanospheres, microrods, hexagonal prisms, microtubes, microdisks, polygonal columns, and hexagonal tablets, can be obtained with different reaction times, reaction temperatures, molar ratios of capping agent to sodium hydroxide, and by varying the binary acids. Fourier transform infrared, thermogravimetric analysis, and upconversion luminescence spectra measurements indicate that the synthesized NaYF(4):Yb/Er products with hydrophilic carboxyl-functionalized surface offer efficient upconversion luminescent performance. Furthermore, the antibody/secondary antibody conjugation can be realized by the carboxyl-functionalized surfaces of the upconversion phosphors, thus indicating the potential bioapplications of these kinds of materials. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Volatility of atmospherically relevant alkylaminium carboxylate salts.

    Science.gov (United States)

    Lavi, Avi; Segre, Enrico; Gomez-Hernandez, Mario; Zhang, Renyi; Rudich, Yinon

    2015-05-14

    Heterogeneous neutralization reactions of ammonia and alkylamines with sulfuric acid play an important role in aerosol formation and particle growth. However, little is known about the physical and chemical properties of alkylaminium salts of organic acids. In this work we studied the thermal stability and volatility of alkylaminium carboxylate salts of short aliphatic alkylamines with monocarboxylic and dicarboxylic acids. The enthalpy of vaporization and saturation vapor pressure at 298 K were derived using the kinetic model of evaporation and the Clausius-Clapeyron relation. The vapor pressure of alkylaminium dicarboxylate salts is ∼10(-6) Pa, and the vaporization enthalpy ranges from 73 to 134 kJ mol(-1). Alkylaminium monocarboxylate salts show high thermal stability, and their thermograms do not follow our evaporation model. Hence, we inferred their vapor pressure from their thermograms as comparable to that of ammonium sulfate (∼10(-9) Pa). Further characterization showed that alkylaminium monocarboxylates are room temperature protic ionic liquids (RTPILs) that are more hygroscopic than ammonium sulfate (AS). We suggest that the irregular thermograms result from an incomplete neutralization reaction leading to a mixture of ionic and nonionic compounds. We conclude that these salts are expected to contribute to new particle formation and particle growth under ambient conditions and can significantly enhance the CCN activity of mixed particles in areas where SO2 emissions are regulated.

  8. N-Alkylation Using Sodium Triacetoxyborohydride with Carboxylic Acids as Alkyl Sources.

    Science.gov (United States)

    Tamura, Satoru; Sato, Keigo; Kawano, Tomikazu

    2018-01-01

    A versatile N-alkylation was performed using sodium triacetoxyborohydride and carboxylic acid as an alkyl source. The combination of these reagents furnished products different from those given previously by a similar reaction. Moreover, the mild conditions of our method allowed some functional groups to remain through the reaction, whereas they would react and be converted into other moieties in the similar reductive N-alkylation reported previously. Herein, we provide a new procedure for the preparation of various compounds containing nitrogen atoms.

  9. Edge-carboxylated graphene nanoflakes from nitric acid oxidised arc-discharge material

    OpenAIRE

    NICOLOSI, VALERIA

    2010-01-01

    PUBLISHED Graphene nanoflakes (GNFs) with average diameters of 30 nm have been prepared by a single-step oxidation procedure using single-wall carbon nanotube arc-discharge material and nitric acid. The GNFs are predominately single sheets containing a small number of internal defects. The edges are decorated with primarily carboxylic acid groups which allow facile chemical functionalisation and cross-linking of the fragments using multivalent cations

  10. Surface radiological investigation of Trench 5 in Waste Area Grouping 7 at Oak Ridge National Laboratory, Oak Ridge, Tennessee

    International Nuclear Information System (INIS)

    Goff, D.D.

    1991-08-01

    A surface radiological investigation of areas encompassing Trench 5 on the Oak Ridge Reservation (ORR) was conducted from May 1990 through November 1990. This survey was led by the author, assisted by various members of the Measurement Applications and Development (MAD) group of the Health and Safety Research Division (HASRD) of Oak Ridge National Laboratory (ORNL) in Oak Ridge, Tennessee. The purpose of the investigation was to determine the presence, nature, and extent of surface radiological contamination at Trench 5, the Homogeneous Reactor Experiment fuel wells, and surrounding areas. Based on the data obtained in the field, interim corrective measures were recommended to limit human exposure to radioactivity and to minimize insult to the environment. It should be stressed that this project was not intended to be a complete site characterization but rather to be a preliminary investigation into the potential contamination problem that might exist as a result of past operations at Trench 5

  11. Skidding accidents : considerations on road surface and vehicle characteristics : summary of the present situation. Provisional recommendation concerning skidding resistance of road surfaces investigation programme. Interim report of the SWOV Working Group "Tyres, road surfaces and skidding accidents"

    NARCIS (Netherlands)

    SWOV Working Group "Tyres, road surfaces and skidding accidents"

    1970-01-01

    This is the first report of SWOV Working Group "Tyres, road surfaces and skidding accidents". Skidding is considered to be an important contributory factor in traffic accidents. Skidding can in principle be prevented in two ways, viz: (1) reduction of the minimum necessary friction, and (2)

  12. Operable Unit 3-13, Group 3, Other Surface Soils Remediation Sets 4-6 (Phase II) Waste Management Plan

    International Nuclear Information System (INIS)

    G. L. Schwendiman

    2006-01-01

    This Waste Management Plan describes waste management and waste minimization activities for Group 3, Other Surface Soils Remediation Sets 4-6 (Phase II) at the Idaho Nuclear Technology and Engineering Center located within the Idaho National Laboratory. The waste management activities described in this plan support the selected response action presented in the Final Record of Decision for Idaho Nuclear Technology and Engineering Center, Operable Unit 3-13. This plan identifies the waste streams that will be generated during implementation of the remedial action and presents plans for waste minimization, waste management strategies, and waste disposition

  13. Interaction of paracetamol and 125I-paracetamol with surface groups of activated carbon. Theoretical and experimental study

    International Nuclear Information System (INIS)

    Daniel Hernandez-Valdes; Ulises Jauregui-Haza; Carlos Enriquez-Victorero; Melvin Arias

    2015-01-01

    The selection of activated carbon (AC) filters for water decontamination is currently carried out empirically. The low concentrations of drugs in the environment make the radioisotope labeling a valuable tool for physical and chemical studies of the adsorption process. A theoretical study of paracetamol and 125 I-paracetamol adsorption onto AC was performed to evaluate the interactions between pollutants and surface groups (SG) of AC. Paracetamol was labeled with 125 I and adsorption isotherms were obtained using radioanalytical and spectrophotometric techniques. The radioanalytical method overestimates the paracetamol adsorption. The validity of the chosen approach for qualitative assessment of SG influence over the adsorption process was demonstrated. (author)

  14. Biocompatible and detectable carboxylated nanodiamond on human cell

    International Nuclear Information System (INIS)

    Liu, K-K; Cheng, C-L; Chang, C-C; Chao, J-I

    2007-01-01

    Surface-modified carboxylated nanometre-sized diamond (cND) has been applied for the conjugation of biological molecules such as DNA and protein. In this study, we evaluated the biocompatibility and detection of cNDs and carbon nanotubes on human lung A549 epithelial cells and HFL-1 normal fibroblasts. Treatment with 5 or 100 nm cND particles, 0.1-100 μg ml -1 , did not reduce the cell viability and alter the protein expression profile in lung cells; however, carbon nanotubes induced cytotoxicity in these cells. The cNDs particles were accumulated in A549 cells, which were observed by atomic force microscopy and laser scanning confocal microscopy. Both 5 and 100 nm cNDs particles exhibited the green fluorescence and were ingested into cells. Moreover, the fluorescence intensities were increased in cells via a concentration-dependent manner after treatment with 5 and 100 nm cNDs, which can be detected by flow cytometer analysis. The fluorescence intensities of 5 nm cNDs were relative higher than 100 nm cNDs in cells at equal concentration treatment. The observation demonstrated that cND-interacting with cell is detectable by a confocal microscope, flow cytometer and atomic force microscope. These nanoparticles may be useful for further biomedical applications based on the properties of uptake ability, detectability and little cytotoxicity in human cells

  15. Biocompatible and detectable carboxylated nanodiamond on human cell

    Energy Technology Data Exchange (ETDEWEB)

    Liu, K-K [Institute of Pharmacology and Toxicology, Tzu Chi University, Hualien 970, Taiwan (China); Cheng, C-L [Department of Physics, National Dong Hwa University, Hualien 974, Taiwan (China); Chang, C-C [Department of Biological Science and Technology, National Chiao Tung University, Hsin-Chu 300, Taiwan (China); Chao, J-I [Institute of Pharmacology and Toxicology, Tzu Chi University, Hualien 970, Taiwan (China)

    2007-08-15

    Surface-modified carboxylated nanometre-sized diamond (cND) has been applied for the conjugation of biological molecules such as DNA and protein. In this study, we evaluated the biocompatibility and detection of cNDs and carbon nanotubes on human lung A549 epithelial cells and HFL-1 normal fibroblasts. Treatment with 5 or 100 nm cND particles, 0.1-100 {mu}g ml{sup -1}, did not reduce the cell viability and alter the protein expression profile in lung cells; however, carbon nanotubes induced cytotoxicity in these cells. The cNDs particles were accumulated in A549 cells, which were observed by atomic force microscopy and laser scanning confocal microscopy. Both 5 and 100 nm cNDs particles exhibited the green fluorescence and were ingested into cells. Moreover, the fluorescence intensities were increased in cells via a concentration-dependent manner after treatment with 5 and 100 nm cNDs, which can be detected by flow cytometer analysis. The fluorescence intensities of 5 nm cNDs were relative higher than 100 nm cNDs in cells at equal concentration treatment. The observation demonstrated that cND-interacting with cell is detectable by a confocal microscope, flow cytometer and atomic force microscope. These nanoparticles may be useful for further biomedical applications based on the properties of uptake ability, detectability and little cytotoxicity in human cells.

  16. Mechanism of catalytic action of oxide systems in reactions of aldehyde oxidation to carboxylic acids

    International Nuclear Information System (INIS)

    Andrushkevich, T.V.

    1997-01-01

    Mechanism of selective action of oxide catalysts (on the base of V 2 O 4 , MoO 3 ) of aldehyde oxidation to acids is considered, reaction acrolein oxidation to acrylic acid is taken as an example. Multistage mechanism of the process is established; it involves consequent transformation of coordination-bonded aldehyde into carbonyl-bonded aldehyde and symmetric carboxylate. Principles of active surface construction are formulated, they take into account the activity of stabilization center of concrete intermediate compound and bond energy of oxygen with surface. (author)

  17. Temporal formation of optical anisotropy and surface relief during polarization holographic recording in polymethylmethacrylate with azobenzene side groups

    Science.gov (United States)

    Sasaki, Tomoyuki; Izawa, Masahiro; Noda, Kohei; Nishioka, Emi; Kawatsuki, Nobuhiro; Ono, Hiroshi

    2014-03-01

    The formation of polarization holographic gratings with both optical anisotropy and surface relief (SR) deformation was studied for polymethylmethacrylate with azobenzene side groups. Temporal contributions of isotropic and anisotropic phase gratings were simultaneously determined by observing transitional intensity and polarization states of the diffraction beams and characterizing by means of Jones calculus. To clarify the mechanism of SR deformation, cross sections of SR were characterized based on the optical gradient force model; experimental observations were in good agreement with the theoretical expectation. We clarified that the anisotropic phase change originating in the reorientation of the azobenzene side groups was induced immediately at the beginning of the holographic recording, while the response time of the isotropic phase change originating in the molecular migration due to the optical gradient force was relatively slow.

  18. Functional groups grafted nonwoven fabrics for blood filtration-The effects of functional groups and wettability on the adhesion of leukocyte and platelet

    Energy Technology Data Exchange (ETDEWEB)

    Yang Chao [State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Cao Ye [Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Peking Union Medical College, Chengdu 610081 (China); Sun Kang, E-mail: ksun@sjtu.edu.cn [State Key Lab of Metal Matrix Composites, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Liu Jiaxin; Wang Hong [Institute of Blood Transfusion, Chinese Academy of Medical Sciences and Peking Union Medical College, Chengdu 610081 (China)

    2011-01-15

    In this work, the effects of grafted functional groups and surface wettability on the adhesion of leukocyte and platelet were investigated by the method of blood filtration. The filter materials, poly(butylene terephthalate) nonwoven fabrics bearing different functional groups including hydroxyl (OH), carboxyl (COOH), sulfonic acid group (SO{sub 3}H) and zwitterionic sulfobetaine group ({sup +}N((CH{sub 3}){sub 2})(CH{sub 2}){sub 3}SO{sub 3}{sup Circled-Minus }) with controllable wettability were prepared by UV radiation grafting vinyl monomers with these functional groups. Our results emphasized that both surface functional groups and surface wettability had significant effects on the adhesion of leukocyte and platelet. In the case of filter materials with the same wettability, leukocytes adhering to filter materials decreased in the order: the surface bearing OH only > the surface bearing both OH and COOH > the surface bearing sulfobetaine group > the surface bearing SO{sub 3}H, while platelets adhering to filter materials decreased as the following order: the surface bearing SO{sub 3}H > the surface bearing both OH and COOH > the surface bearing OH only > the surface bearing sulfobetaine group. As the wettability of filter materials increased, both leukocyte and platelet adhesion to filter materials declined, except that leukocyte adhesion to the surface bearing OH only remained unchanged.

  19. Determination of Carboxylic Acids and Water-soluble Inorganic Ions ...

    African Journals Online (AJOL)

    NICO

    radiation balance.4,5 Major water-soluble inorganic ions are associated with atmospheric ... molecular weight carboxylic acids in aerosol samples collected from a rural ... include biomass burning, agriculture, livestock and soil dust. Tropical ...

  20. Osteoblast response to oxygen functionalised plasma polymer surfaces

    International Nuclear Information System (INIS)

    Kelly, Jonathan M.

    2001-01-01

    Thin organic films with oxygen-carbon functionalities were deposited from plasmas containing vapour of the small organic compounds: allyI alcohol, methyl vinyl ketone and acrylic acid with octadiene. Characterisation of the deposits was carried out using X-ray photoelectron spectroscopy, in conjunction with chemical derivatisation, and this showed that plasma polymers retained high levels of original monomer functionality when the plasmas were sustained at low power for a given monomer vapour flow rate. High levels of attachment of rat osteosarcoma (ROS 17/2.8) cells were observed on surfaces that had high concentrations of hydroxyl and carbonyl functionalities and intermediate concentrations of carboxyl functionality. Cells did not attach to the octadiene plasma polymer. Cell attachment to carboxyl and methyl functionalised self-assembled monolayers increased with increasing concentration of surface carboxyl groups. Adsorption of the extracellular matrix protein fibronectin to acrylic acid/octadiene plasma copolymers was studied by enzyme linked immunosorbent assays and by I 125 radiolabelling. Fibronectin adsorbed in largest amounts to surfaces with intermediate concentrations of carboxyl functionality. Spreading of ROS cells and rat bone marrow stromal cells (BMSC) was characterised by computer image analysis. Cell spreading in media containing 10% serum, on a surface deposited from a plasma of 5 O/o acrylic acid was much greater than on the octadiene plasma polymer while most extensive cell spreading was observed on these surfaces when preadsorbed with fibronectin. Growth (proliferation) of BMSC was assessed over nine days and was found to be faster on an 50% acrylic acid plasma polymer than on tissue culture polystyrene or a hydrocarbon plasma polymer, though cell growth was fastest on fibronectin precoated substrates. Expression of cellular alkaline phosphatase, collagen and calcium reached similar levels on the 50% acrylic acid plasma polymer, tissue culture

  1. Osteoblast response to oxygen functionalised plasma polymer surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, Jonathan M

    2001-07-01

    Thin organic films with oxygen-carbon functionalities were deposited from plasmas containing vapour of the small organic compounds: allyI alcohol, methyl vinyl ketone and acrylic acid with octadiene. Characterisation of the deposits was carried out using X-ray photoelectron spectroscopy, in conjunction with chemical derivatisation, and this showed that plasma polymers retained high levels of original monomer functionality when the plasmas were sustained at low power for a given monomer vapour flow rate. High levels of attachment of rat osteosarcoma (ROS 17/2.8) cells were observed on surfaces that had high concentrations of hydroxyl and carbonyl functionalities and intermediate concentrations of carboxyl functionality. Cells did not attach to the octadiene plasma polymer. Cell attachment to carboxyl and methyl functionalised self-assembled monolayers increased with increasing concentration of surface carboxyl groups. Adsorption of the extracellular matrix protein fibronectin to acrylic acid/octadiene plasma copolymers was studied by enzyme linked immunosorbent assays and by I{sup 125} radiolabelling. Fibronectin adsorbed in largest amounts to surfaces with intermediate concentrations of carboxyl functionality. Spreading of ROS cells and rat bone marrow stromal cells (BMSC) was characterised by computer image analysis. Cell spreading in media containing 10% serum, on a surface deposited from a plasma of 5 O/o acrylic acid was much greater than on the octadiene plasma polymer while most extensive cell spreading was observed on these surfaces when preadsorbed with fibronectin. Growth (proliferation) of BMSC was assessed over nine days and was found to be faster on an 50% acrylic acid plasma polymer than on tissue culture polystyrene or a hydrocarbon plasma polymer, though cell growth was fastest on fibronectin precoated substrates. Expression of cellular alkaline phosphatase, collagen and calcium reached similar levels on the 50% acrylic acid plasma polymer, tissue

  2. Comparative effects of graphene and graphene oxide on copper toxicity to Daphnia magna: Role of surface oxygenic functional groups.

    Science.gov (United States)

    Liu, Yingying; Fan, Wenhong; Xu, Zhizhen; Peng, Weihua; Luo, Shenglian

    2018-05-01

    Although the risk of graphene materials to aquatic organisms has drawn wide attention, the combined effects of graphene materials with other contaminants such as toxic metals, which may bring about more serious effects than graphene materials alone, have seldom been explored. Herein, the effects of graphene (GN) and graphene oxide (GO, an important oxidized derivative of graphene) on copper (Cu) toxicity to Daphnia magna were systematically investigated. The results indicated that GN remarkably increased the Cu accumulation in D. magna and enhanced the oxidative stress injury caused by Cu, whereas did not significantly alter D. magna acute mortality within the tested Cu concentrations (0-200 μg L -1 ). On the contrary, GO significantly decreased the Cu accumulation in D. magna and alleviated the oxidative stress injury caused by Cu. Meanwhile, the presence of GO significantly reduced the mortality of D. magna when Cu concentration exceeded 50 μg L -1 . The different effects of GN and GO on Cu toxicity were possibly dependent on the action of surface oxygenic functional group. Because of the introduction of surface oxygenic functional groups, the adsorption ability to metal ions, stability in water and interaction mode with organisms of GO are quite different from that of GN, causing different effects on Cu toxicity. This study provides important information on the bioavailability and toxicity of heavy metals as affected by graphene materials in natural water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  3. Surface modification of magnetite nanoparticles for biomedical applications

    International Nuclear Information System (INIS)

    Barrera, Carola; Herrera, Adriana; Zayas, Yashira; Rinaldi, Carlos

    2009-01-01

    The preparation of magnetite nanoparticles with narrow size distributions using poly(ethylene glycol) (PEG-COOH) or carboxymethyl dextran (CMDx) chains covalently attached to the particle surface using carbodiimide chemistry is described. Particles were synthesized by thermal decomposition and modified with 3-aminopropyl trimethoxysilane (APS) to render particles with reactive amine groups (-NH 2 ) on their surface. Amines were then reacted with carboxyl groups in PEG-COOH or CMDx using carbodiimide chemistry in water. The size and stability of the functionalized magnetic nanoparticles was studied as a function of pH and ionic strength using dynamic light scattering and zeta potential measurements.

  4. WISEP J004701.06+680352.1: AN INTERMEDIATE SURFACE GRAVITY, DUSTY BROWN DWARF IN THE AB DOR MOVING GROUP

    Energy Technology Data Exchange (ETDEWEB)

    Gizis, John E. [Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Allers, Katelyn N. [Department of Physics and Astronomy, Bucknell University, Lewisburg, PA 17837 (United States); Liu, Michael C. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu HI 96822 (United States); Harris, Hugh C. [US Naval Observatory, Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, AZ 86001 (United States); Faherty, Jacqueline K. [Department of Terrestrial Magnetism, Carnegie Institution of Washington 5241 Broad Branch Road NW, Washington, DC 20015 (United States); Burgasser, Adam J. [Center for Astrophysics and Space Science, University of California San Diego, La Jolla, CA 92093 (United States); Kirkpatrick, J. Davy [Infrared Processing and Analysis Center, MS 100-22, California Institute of Technology, Pasadena, CA 91125 (United States)

    2015-02-01

    We present spectroscopy, astrometry, and photometry of the brown dwarf WISEP J004701.06+680352.1 (W0047+68), an unusually red field L dwarf at a distance of 12.2 ± 0.4 pc. The three-dimensional space motion identifies it as a member of the AB Dor Moving Group, an identification supported by our classification of W0047+68 as intermediate surface gravity (INT-G) using the Allers and Liu near-infrared classification system. This moving group membership implies near-solar metallicity, age ∼100-125 Myr, M ≈ 0.018 M {sub ☉}, and log g ≈ 4.5; the thick condensate clouds needed to explain the infrared spectrum are, therefore, a result of surface gravity that is lower than that of ordinary field brown dwarfs. From the observed luminosity and evolutionary model radius, we find T {sub eff} ≈ 1300 K, a temperature normally associated with early T dwarfs. Thick clouds are also used to explain the spectral properties of directly imaged giant planets, and we discuss the successes and challenges for such substellar models in matching the observed optical and infrared spectra. W0047+68 shows that cloud thickness is more sensitive to intermediate surface gravity than in most models. We also present a trigonometric parallax of the dusty L6 dwarf 2MASS J21481628+4003593. It lies at 8.060 ± 0.036 parsecs; its astrometry is consistent with the view that it is older and metal-rich.

  5. Synthesis and application of a new carboxylated cellulose derivative. Part I: Removal of Co(2+), Cu(2+) and Ni(2+) from monocomponent spiked aqueous solution.

    Science.gov (United States)

    Teodoro, Filipe Simões; Ramos, Stela Nhandeyara do Carmo; Elias, Megg Madonyk Cota; Mageste, Aparecida Barbosa; Ferreira, Gabriel Max Dias; da Silva, Luis Henrique Mendes; Gil, Laurent Frédéric; Gurgel, Leandro Vinícius Alves

    2016-12-01

    A new carboxylated cellulose derivative (CTA) was prepared from the esterification of cellulose with 1,2,4-Benzenetricarboxylic anhydride. CTA was characterized by percent weight gain (pwg), amount of carboxylic acid groups (nCOOH), elemental analysis, FTIR, TGA, solid-state (13)C NMR, X-ray diffraction (DRX), specific surface area, pore size distribution, SEM and EDX. The best CTA synthesis condition yielded a pwg and nCOOH of 94.5% and 6.81mmolg(-1), respectively. CTA was used as an adsorbent material to remove Co(2+), Cu(2+) and Ni(2+) from monocomponent spiked aqueous solution. Adsorption studies were developed as a function of the solution pH, contact time and initial adsorbate concentration. Langmuir model better fitted the experimental adsorption data and the maximum adsorption capacities estimated by this model were 0.749, 1.487 and 1.001mmolg(-1) for Co(2+), Cu(2+) and Ni(2+), respectively. The adsorption mechanism was investigated by using isothermal titration calorimetry. The values of ΔadsH° were in the range from 5.36 to 8.09kJmol(-1), suggesting that the mechanism controlling the phenomenon is physisorption. Desorption and re-adsorption studies were also performed. Desorption and re-adsorption efficiencies were closer to 100%, allowing the recovery of both metal ions and CTA adsorbent. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Controlled Electrochemical Carboxylation of Graphene To Create a Versatile Chemical Platform for Further Functionalization

    DEFF Research Database (Denmark)

    Bjerglund Pedersen, Emil; Kongsfelt, Mikkel; Shimizu, Kyoko

    2014-01-01

    An electrochemical approach is introduced for the versatile carboxylation of multi-layered graphene in 0.1 M Bu4NBF4/MeCN. First, the graphene substrate (i.e., graphene chemically vapor-deposited on Ni) is negatively charged at -1.9 V versus Ag/AgI in a degassed solution to allow for intercalation...... of Bu4N+ and, thereby, separation of the individual graphene sheets. In the next step, the strongly activated and nucleophilic graphene is allowed to react with added carbon dioxide in an addition reaction, introducing carboxylate groups stabilized by Bu4N+ already present. This procedure may be carried...... solution at the graphene electrode for a given time. The same functionalization degree is obtained for all multi-layered regions, independent of the number of graphene sheets, which is due to the fact that the entire graphene structure is opened in response to the intercalation of Bu4N+. Hence...

  7. Thermodynamics of formation of cadmium dicarboxylate and carboxylate mixed complexes with benzimidazole

    Energy Technology Data Exchange (ETDEWEB)

    Kharitonov, G V; Bolotov, V M; Kharitonova, R I [Voronezhskij Tekhnologicheskij Inst. (USSR)

    1980-01-01

    Thermodynamic parameters of the mixed complexing of cadmium propionate, butyrate, valerate, succinate, maleinate and malate with benzimidazole in 20 % aqUeous-ethanol solution of 0.1 M KNO/sub 3/ are studied using polarographic method. It is shown that stability of mixed complexes of cadmium carboxylates with benzimidazole is connected with the process enthalpy and is determined by covalency of the metal-carboxylate bond. Increasing length of hydrocarbon chain of acyl group of monobasic acids hampers amine coordination with central complexing agent (..delta..S<0). The presence of dicarboxylate-ion in the inner coordination sphere decreases the enthalpy and increases the entropy of the process (..delta..S>0).

  8. Carboxylic Terminated Thermo-Responsive Copolymer Hydrogel and Improvement in Peptide Release Profile

    Directory of Open Access Journals (Sweden)

    Zi-Kun Rao

    2018-02-01

    Full Text Available To improve the release profile of peptide drugs, thermos-responsive triblock copolymer poly (ε-caprolactone-co-p-dioxanone-b-poly (ethylene glycol-b-poly (ε-caprolactone-co-p-dioxanone (PECP was prepared and end capped by succinic anhydride to give its carboxylic terminated derivative. Both PCEP block copolymer and its end group modified derivative showed temperature-dependent reversible sol-gel transition in water. The carboxylic end group could significantly decrease the sol-gel transition temperature by nearly 10 °C and strengthen the gel due to enhanced intermolecular force among triblock copolymer chains. Furthermore, compared with the original PECP triblock copolymer, HOOC–PECP–COOH copolymer displayed a retarded and sustained release profile for leuprorelin acetate over one month while effectively avoiding the initial burst. The controlled release was believed to be related to the formation of conjugated copolymer-peptide pair by ionic interaction and enhanced solubility of drug molecules into the hydrophobic domains of the hydrogel. Therefore, carboxyl terminated HOOC–PECP–COOH hydrogel was a promising and well-exhibited sustained release carrier for peptide drugs with the advantage of being able to develop injectable formulation by simple mixing.

  9. Synthesis, surface group modification of 3D MnV2O6 nanostructures and adsorption effect on Rhodamine B

    International Nuclear Information System (INIS)

    Zhang, Wanqun; Shi, Lei; Tang, Kaibin; Liu, Zhongping

    2012-01-01

    Highlights: ► Fabrication of urchin-like MnV 2 O 6 with oxygen-containing surface groups. ► Mn 0.5 V 2 O 5 ·nH 2 O as an intermediate product holds the key to the final products. ► 3D architectures of MnV 2 O 6 with oxygen-containing surface groups as sorbent. ► The sorbent shows a good adsorption ability. -- Abstract: Highly uniform 3D MnV 2 O 6 nanostructures modified by oxygen functional groups (-COO-) were successfully prepared in large quantities by an approach involving preparation of vanadyl ethylene glycolate as the precursor. The growth and self-assembly of MnV 2 O 6 nanobelts and nanorods could be readily tuned by additive species and quantities, which brought different morphologies and sizes to the final products. With a focus on the regulation of structure, the formation process of 3D architectures of MnV 2 O 6 by self-assembly of nanobelts was followed by field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The consecutive processes of vanadyl ethylene glycolate and benzoyl peroxide assisted formation of layered structure Mn 0.5 V 2 O 5 ·nH 2 O, growth of aligned MnV 2 O 6 nanobelts, and oriented assembly were proposed for the growth mechanism. The band gap vs. different morphology was also studied. Optical characterization of these MnV 2 O 6 with different morphologies showed direct bandgap energies at 1.8–1.95 eV. The adsorption properties of 3D MnV 2 O 6 nanostructures synthesized under different conditions were investigated through the removal test of Rhodamine B in aqueous water, and the 3D nanostructures synthesized with 30 g L −1 benzoyl peroxide showed good adsorption capability of Rhodamine B.

  10. Surface modification and functionalization of carbon nanotube with some organic compounds

    International Nuclear Information System (INIS)

    Le, Van Thu; Ngo, Cao Long; Le, Quoc Trung; Ngo, Trinh Tung; Nguyen, Duc Nghia; Vu, Minh Thanh

    2013-01-01

    In this work the surface modification and functionalization of carbon nanotubes (CNTs) were investigated. CNTs were firstly treated by acid mixture H 2 SO 4 /HNO 3 to introduce the carboxylic group onto the surface of CNTs. This carboxylic group was used as reaction precursor in the functionalization. Two functional groups, dodecylamine (DDA) and 3-aminopropyl triethoxysilane (3-APTES), were successfully covalently attached to CNTs. The functionalized CNTs were characterized by Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, differential scanning calorimetry and thermal gravimetric analysis (DSC/TGA) and transmission electron microscopy (TEM) methods. The CNTs attached to the organofunctional moieties have greater versatility for further utilization in different application fields such as biology, nanocomposites, solar energy, etc. (paper)

  11. Characterisation and application of new carboxylic acid-functionalised ruthenium complexes as dye-sensitisers for solar cells

    DEFF Research Database (Denmark)

    Duprez, Virginie; Biancardo, Matteo; Krebs, Frederik C

    2007-01-01

    A series of ruthenium complexes with and without TiO2, anchoring carboxylic acid groups have been synthesised and characterised using nuclear magnetic resonance (NMR), UV-vis and luminescence. These complexes were adsorbed on thin films of the wide band-gap semiconductor anatase and were tested a...

  12. Microscopic mechanism of electron transfer through the hydrogen bonds between carboxylated alkanethiol molecules connected to gold electrodes

    KAUST Repository

    Li, Yang; Tu, Xingchen; Wang, Minglang; Wang, Hao; Sanvito, Stefano; Hou, Shimin

    2014-01-01

    © 2014 AIP Publishing LLC. The atomic structure and the electron transfer properties of hydrogen bonds formed between two carboxylated alkanethiol molecules connected to gold electrodes are investigated by employing the non-equilibrium Green's function formalism combined with density functional theory. Three types of molecular junctions are constructed, in which one carboxyl alkanethiol molecule contains two methylene, -CH2, groups and the other one is composed of one, two, or three -CH2 groups. Our calculations show that, similarly to the cases of isolated carboxylic acid dimers, in these molecular junctions the two carboxyl, -COOH, groups form two H-bonds resulting in a cyclic structure. When self-interaction corrections are explicitly considered, the calculated transmission coefficients of these three H-bonded molecular junctions at the Fermi level are in good agreement with the experimental values. The analysis of the projected density of states confirms that the covalent Au-S bonds localized at the molecule-electrode interfaces and the electronic coupling between -COOH and S dominate the low-bias junction conductance. Following the increase of the number of the -CH2 groups, the coupling between -COOH and S decreases deeply. As a result, the junction conductance decays rapidly as the length of the H-bonded molecules increases. These findings not only provide an explanation to the observed distance dependence of the electron transfer properties of H-bonds, but also help the design of molecular devices constructed through H-bonds.

  13. Crystal structure of 7,7-dimethyl-6-methylidenetricyclo[6.2.1.01,5]undecane-2-carboxylic acid

    Directory of Open Access Journals (Sweden)

    Noureddine Beghidja

    2015-02-01

    Full Text Available In the title compound, C15H22O2, both five-membered rings display an envelope conformation whereas the six-membered ring displays a chair conformation. In the crystal, pairs of O—H...O hydrogen bonds between carboxylic groups link molecules, related by a twofold rotation axis, into supramolecular dimers.

  14. Microscopic mechanism of electron transfer through the hydrogen bonds between carboxylated alkanethiol molecules connected to gold electrodes

    KAUST Repository

    Li, Yang

    2014-11-07

    © 2014 AIP Publishing LLC. The atomic structure and the electron transfer properties of hydrogen bonds formed between two carboxylated alkanethiol molecules connected to gold electrodes are investigated by employing the non-equilibrium Green\\'s function formalism combined with density functional theory. Three types of molecular junctions are constructed, in which one carboxyl alkanethiol molecule contains two methylene, -CH2, groups and the other one is composed of one, two, or three -CH2 groups. Our calculations show that, similarly to the cases of isolated carboxylic acid dimers, in these molecular junctions the two carboxyl, -COOH, groups form two H-bonds resulting in a cyclic structure. When self-interaction corrections are explicitly considered, the calculated transmission coefficients of these three H-bonded molecular junctions at the Fermi level are in good agreement with the experimental values. The analysis of the projected density of states confirms that the covalent Au-S bonds localized at the molecule-electrode interfaces and the electronic coupling between -COOH and S dominate the low-bias junction conductance. Following the increase of the number of the -CH2 groups, the coupling between -COOH and S decreases deeply. As a result, the junction conductance decays rapidly as the length of the H-bonded molecules increases. These findings not only provide an explanation to the observed distance dependence of the electron transfer properties of H-bonds, but also help the design of molecular devices constructed through H-bonds.

  15. Two dialkylammonium salts of 2-amino-4-nitrobenzoic acid: crystal structures and Hirshfeld surface analysis

    Directory of Open Access Journals (Sweden)

    James L. Wardell

    2016-12-01

    Full Text Available The crystal structures of two ammonium salts of 2-amino-4-nitrobenzoic acid are described, namely dimethylazanium 2-amino-4-nitrobenzoate, C2H8N+·C7H5N2O4−, (I, and dibutylazanium 2-amino-4-nitrobenzoate, C8H20N+·C7H5N2O4−, (II. The asymmetric unit of (I comprises a single cation and a single anion. In the anion, small twists are noted for the carboxylate and nitro groups from the ring to which they are connected, as indicated by the dihedral angles of 11.45 (13 and 3.71 (15°, respectively; the dihedral angle between the substituents is 7.9 (2°. The asymmetric unit of (II comprises two independent pairs of cations and anions. In the cations, different conformations are noted in the side chains in that three chains have an all-trans [(+-antiperiplanar] conformation, while one has a distinctive kink resulting in a (+-synclinal conformation. The anions, again, exhibit twists with the dihedral angles between the carboxylate and nitro groups and the ring being 12.73 (6 and 4.30 (10°, respectively, for the first anion and 8.1 (4 and 12.6 (3°, respectively, for the second. The difference between anions in (I and (II is that in the anions of (II, the terminal groups are conrotatory, forming dihedral angles of 17.02 (8 and 19.0 (5°, respectively. In each independent anion of (I and (II, an intramolecular amino-N—H...O(carboxylate hydrogen bond is formed. In the crystal of (I, anions are linked into a jagged supramolecular chain by charge-assisted amine-N—H...O(carboxylate hydrogen bonds and these are connected into layers via charge-assisted ammonium-N—H...O(carboxylate hydrogen bonds. The resulting layers stack along the a axis, being connected by nitro-N—O...π(arene and methyl-C—H...O(nitro interactions. In the crystal of (II, the anions are connected into four-ion aggregates by charge-assisted amino-N—H...O(carboxylate hydrogen bonding. The formation of ammonium-N—H...O(carboxylate hydrogen bonds, involving

  16. Hydroxy, carboxylic and amino acid functionalized ...

    Indian Academy of Sciences (India)

    The surface functionalization of magnetite nanopar- ticles with a .... incubated with 200 µL at 5% CO2 with protein pre- cipitation solution ... surface.17. Hence, the interaction between the coating material .... electrostatic repulsion. In the case of ...

  17. Role of Carboxylate ligands in the Synthesis of AuNPs: Size Control, Molecular Interaction and Catalytic Activity

    KAUST Repository

    Aljohani, Hind Abdullah

    2016-05-22

    Nanoparticles (NPs) are the basis of nanotechnology and finding numerous applications in various fields such as health, electronics, environment, personal care products, transportation, and catalysis. To fulfill these functions, the nanoparticles must be synthesized, passivated to control their chemical reactivity, stabilized against aggregation and functionalized to achieve specific performances. The chemistry of metal nanoparticles especially that of noble metals (Gold, Platinum…) is a growing field. The nanoparticles have indeed different properties from those of the corresponding bulk material. These properties are largely influenced by several parameters; the most important are the size, shape, and the local environment of the nanoparticles. One of the most common synthetic methods for the preparation of gold nanoparticles (AuNPs) is based on stabilization by citrate. Since it was reported first by Turkevich et al. in 1951, this synthetic scheme has been widely used, studied and a substantial amount of important information regarding this system has been reported in the literature. The most popular method developed by Frens for controlling the size of the noble gold nanoparticles based on citrate was achieved by varying the concentration of sodium citrate. Despite a large number of investigations focused on utilizing Cit-AuNPs, the structural details of citrate anions adsorbed on the AuNP surface are still unknown. It is known only that citrate anions “coordinate” to the metal surface by inner sphere complexation of the carboxylate groups and there are trace amounts of AuCl4−, Cl−, and OH− on the metal surface. Moreover, it is generally accepted that the ligand shell morphology of Au nanoparticles can be partly responsible for important properties such as oxidation of carbon monoxide. The use of Au-NPs in heterogeneous catalysis started mostly with Haruta who discovered the effect of particle size on the activity for carbon monoxide oxidation at

  18. Solid state structure of thorium(IV) complexes with common aminopoly-carboxylate ligands

    International Nuclear Information System (INIS)

    Thuery, Pierre

    2011-01-01

    The crystal structures of the complexes formed by reaction of thorium(IV) nitrate with iminodiacetic acid (H 2 IDA), nitrilotriacetic acid (H 3 NTA), and ethylenediaminetetraacetic acid (H 4 EDTA) under hydrothermal conditions are reported. In [Th(HIDA) 2 (C 2 O 4 )].H 2 O (1), the metal atom is chelated by two carboxylate groups from two HIDA - anions and by two oxalate ligands formed in situ; two additional oxygen atoms from two more HIDA - anions complete the ten-coordinate environment of bi-capped square anti-prismatic geometry. The uncoordinated nitrogen atom is protonated and involved in hydrogen bonding. Two different ligands are present in [Th(NTA)(H 2 NTA)(H 2 O)].H 2 O (2), one of them being a O 3 ,N-chelating tri-anion which acts also as a bridge toward two neighboring metal ions, and the other being a bis-monodentate bridging species with an uncoordinated carboxylic arm and a central ammonium group. An aqua ligand completes the nine-coordinated, capped square anti-prismatic metal environment. The EDTA 4- anion in [Th(EDTA)(H 2 O)].2H 2 O (3) is chelating through one oxygen atom from each carboxylate group and the two nitrogen atoms, as in a previously reported molecular complex. Two carboxylate groups are bridging, which, with the addition of an aqua ligand, gives a capped square anti-prismatic coordination polyhedron. Aminopoly-carboxylate ligands have been much investigated in relation with actinide decorporation and nuclear wastes management studies, and the present results add to the structural information available on their complexes with thorium(IV), which has mainly been obtained up to now by extended X-ray absorption fine structure (EXAFS) spectroscopy. In particular, the bridging (non-chelating) coordination mode of H 2 NTA - is a novel feature in this context. All three complexes crystallize as two-dimensional assemblies and are thus novel examples of thorium-organic coordination polymers. (author)

  19. Interactions of lead with carboxyl and hydroxyl-decorated(10, 0) single-walled carbon nanotubes: First-principle calculations

    International Nuclear Information System (INIS)

    Bastos, M.; Camps, I.

    2013-01-01

    Absorption of Pb on a zigzag (10, 0) carbon nanotube (CNT) surface, pure and functionalized with carboxyl (-COOH) and hydroxyl (-OH) groups was investigated using the density functional theory. Binding energy calculations were performed and indicated that adsorption of the Pb metal on the surface of the three nanotubes were stable, through a chemisorption. Therefore, CNTs are a feasible active material for filters that retain such metal. After Pb adsorption, the CNT and COOH-CNT conductivity changed, from semiconductor to half-metallic for CNT and from semiconductor to metallic for COOH-CNT, which can serve as a signal for Pb sensor. In all three cases adsorption produced a change in nanotube magnetism, which can also serve as a sensitive signal for chemical sensors. After adsorption of Pb, the changes in binding energy, charge transfer, conductance and magnetism may lead to the different response in the CNTs-based sensors. Thus, it is expected that these results could provide helpful information for the design and fabrication of the Pb sensing devices.

  20. Gas-phase formaldehyde adsorption isotherm studies on activated carbon: correlations of adsorption capacity to surface functional group density.

    Science.gov (United States)

    Carter, Ellison M; Katz, Lynn E; Speitel, Gerald E; Ramirez, David

    2011-08-01

    Formaldehyde (HCHO) adsorption isotherms were developed for the first time on three activated carbons representing one activated carbon fiber (ACF) cloth, one all-purpose granular activated carbon (GAC), and one GAC commercially promoted for gas-phase HCHO removal. The three activated carbons were evaluated for HCHO removal in the low-ppm(v) range and for water vapor adsorption from relative pressures of 0.1-0.9 at 26 °C where, according to the IUPAC isotherm classification system, the adsorption isotherms observed exhibited Type V behavior. A Type V adsorption isotherm model recently proposed by Qi and LeVan (Q-L) was selected to model the observed adsorption behavior because it reduces to a finite, nonzero limit at low partial pressures and it describes the entire range of adsorption considered in this study. The Q-L model was applied to a polar organic adsorbate to fit HCHO adsorption isotherms for the three activated carbons. The physical and chemical characteristics of the activated carbon surfaces were characterized using nitrogen adsorption isotherms, X-ray photoelectron spectroscopy (XPS), and Boehm titrations. At low concentrations, HCHO adsorption capacity was most strongly related to the density of basic surface functional groups (SFGs), while water vapor adsorption was most strongly influenced by the density of acidic SFGs.

  1. Tyrosine and carboxyl protonation changes in the bacteriorhodopsin photocycle. 1. M412 and L550 intermediates

    International Nuclear Information System (INIS)

    Roepe, P.; Ahl, P.L.; Gupta, S.K.D.; Herzfeld, J.; Rothschild, K.J.

    1987-01-01

    The role of tyrosines in the bacteriorhodopsin (bR) photocycle has been investigated by using Fourier transform infrared (FTIR) and UV difference spectroscopies. Tyrosine contributions to the BR 570 → M 412 FTIR difference spectra recorded at several temperatures and pH's were identified by isotopically labeling tyrosine residues in bacteriorhodopsin. The frequencies and deuterium/hydrogen exchange sensitivities of these peaks and of peaks in spectra of model compounds in several environments suggest that at least two different tyrosine groups participate in the bR photocycle during the formation of M 412 . One group undergoes a tyrosinate → tyrosine conversion during the BR 570 → K 630 transition. A second tyrosine group deprotonates between L 550 and M 412 . Low-temperature UV difference spectra in the 220-350-nm region of both purple membrane suspensions and rehydrated films support these conclusions. The UV spectra also indicate perturbations(s) of one or more tryptophan group(s). Several carboxyl groups appear to undergo a series of protonation changes between BR 570 and M 412 , as indicated by infrared absorption changes in the 1770-1720-cm -1 region. These results are consistent with the existence of a proton wire in bacteriorhodopsin that involves both tyrosine and carboxyl groups

  2. Surface-enhanced Raman spectrum of Gly-Gly adsorbed on the silver colloidal surface

    Science.gov (United States)

    Xiaojuan, Yuan; Huaimin, Gu; Jiwei, Wu

    2010-08-01

    Raman and SERS spectra of homodipeptide Gly-Gly and Gly were recorded and compared in this paper, and band assignment for the functional groups contained in these molecules was analyzed in detail. Time-dependent and pH-dependent SERS spectra of Gly-Gly molecule adsorbed on nano-colloidal silver surface were also studied. The time-dependent SERS spectra of Gly-Gly are characterized by the increase in intensity of bands primarily representing the vibrational signatures emanating from the amino and amide moiety of Gly-Gly molecule. It is found that the adsorption style of Gly-Gly on the silver colloid changes as time goes on; at 5 min after adding the sample to the silver colloid, Gly-Gly adsorbs on silver surface firstly through the carboxylate, amino and amide groups, and then the carboxylate group is far away from the silver surface at 10 min to 3 days. The SERS variation of Gly-Gly with the change of pH suggests that the adsorption style is pH-dependent, the different adsorption behavior of the Gly-Gly occurs on silver surface at different pH values.

  3. Biotransformation of fluorophenyl pyridine carboxylic acids by the model fungus Cunninghamella elegans.

    Science.gov (United States)

    Palmer-Brown, William; Dunne, Brian; Ortin, Yannick; Fox, Mark A; Sandford, Graham; Murphy, Cormac D

    2017-09-01

    1. Fluorine plays a key role in the design of new drugs and recent FDA approvals included two fluorinated drugs, tedizolid phosphate and vorapaxar, both of which contain the fluorophenyl pyridyl moiety. 2. To investigate the likely phase-I (oxidative) metabolic fate of this group, various fluorinated phenyl pyridine carboxylic acids were incubated with the fungus Cunninghamella elegans, which is an established model of mammalian drug metabolism. 3.  19 F NMR spectroscopy established the degree of biotransformation, which varied depending on the position of fluorine substitution, and gas chromatography-mass spectrometry (GC-MS) identified alcohols and hydroxylated carboxylic acids as metabolites. The hydroxylated metabolites were further structurally characterised by nuclear magnetic resonance spectroscopy (NMR), which demonstrated that hydroxylation occurred on the 4' position; fluorine in that position blocked the hydroxylation. 4. The fluorophenyl pyridine carboxylic acids were not biotransformed by rat liver microsomes and this was a consequence of inhibitory action, and thus, the fungal model was crucial in obtaining metabolites to establish the mechanism of catabolism.

  4. Multifunctional PEG-carboxylate copolymer coated superparamagnetic iron oxide nanoparticles for biomedical application

    Science.gov (United States)

    Illés, Erzsébet; Szekeres, Márta; Tóth, Ildikó Y.; Szabó, Ákos; Iván, Béla; Turcu, Rodica; Vékás, Ladislau; Zupkó, István; Jaics, György; Tombácz, Etelka

    2018-04-01

    Biocompatible magnetite nanoparticles (MNPs) were prepared by post-coating the magnetic nanocores with a synthetic polymer designed specifically to shield the particles from non-specific interaction with cells. Poly(ethylene glycol) methyl ether methacrylate (PEGMA) macromonomers and acrylic acid (AA) small molecular monomers were chemically coupled by quasi-living atom transfer radical polymerization (ATRP) to a comb-like copolymer, P(PEGMA-co-AA) designated here as P(PEGMA-AA). The polymer contains pendant carboxylate moieties near the backbone and PEG side chains. It is able to bind spontaneously to MNPs; stabilize the particles electrostatically via the carboxylate moieties and sterically via the PEG moieties; provide high protein repellency via the structured PEG layer; and anchor bioactive proteins via peptide bond formation with the free carboxylate groups. The presence of the P(PEGMA-AA) coating was verified in XPS experiments. The electrosteric (i.e., combined electrostatic and steric) stabilization is efficient down to pH 4 (at 10 mM ionic strength). Static magnetization and AC susceptibility measurements showed that the P(PEGMA-AA)@MNPs are superparamagnetic with a saturation magnetization value of 55 emu/g and that both single core nanoparticles and multicore structures are present in the samples. The multicore components make our product well suited for magnetic hyperthermia applications (SAR values up to 17.44 W/g). In vitro biocompatibility, cell internalization, and magnetic hyperthermia studies demonstrate the excellent theranostic potential of our product.

  5. Blood compatibility of gas plasma-treated diamond-like carbon surface-Effect of physicochemical properties of DLC surface on blood compatibility

    International Nuclear Information System (INIS)

    Mochizuki, Akira; Ogawa, Tatsuhisa; Okamoto, Keishi; Nakatani, Tatsuyuki; Nitta, Yuki

    2011-01-01

    From the knowledge that zwitterion-type polymers show good blood compatibility, the introduction of both cationic and anionic functional groups onto diamond-like carbon (DLC) surface is expected to improve blood compatibility. Thus, DLC films were treated with oxygen and ammonia gas plasmas. The surfaces were characterized in terms of chemical composition by XPS, contact angle, and zeta potential. XPS analysis showed the introductions of a carboxyl group by oxygen plasma treatment and nitrogen atoms by ammonia plasma treatment. The evaluation of blood compatibility for the DLC surfaces was carried out in terms of platelets and the coagulation system. Excellent improvement of platelet compatibility was observed by the treatment with the gas plasmas, regardless of the plasma species. As for the compatibility with the coagulation system, DLC surfaces with a high concentration of carboxyl groups (COOH) markedly activated the system via the intrinsic pathway. However, the surfaces treated with ammonia plasma did not activate the system even though they had high COOH concentration. Measurement of the zeta potential revealed that the ammonia plasma treatment raised the potential from a negative value to a positive one. Though the introduction of amino groups to the surface was not detected directly, the treatment of ammonia plasma changed the electrical state of the DLC surface having COOH group, causing a difference in blood compatibility among the DLCs obtained by various plasma conditions.

  6. Polymorphism in Self-Assembled Structures of 9-Anthracene Carboxylic Acid on Ag(111

    Directory of Open Access Journals (Sweden)

    Bo Xu

    2012-06-01

    Full Text Available Surface self-assembly process of 9-anthracene carboxylic acid (AnCA on Ag(111 was investigated using STM. Depending on the molecular surface density, four spontaneously formed and one annealed AnCA ordered phases were observed, namely a straight belt phase, a zigzag double-belt phase, two simpler dimer phases, and a kagome phase. The two high-density belt phases possess large unit cells on the scale length of 10 nm, which are seldom observed in molecular self-assembled structures. This structural diversity stems from a complicated competition of different interactions of AnCA molecules on metal surface, including intermolecular and molecular-substrate interactions, as well as the steric demand from high molecular surface density.

  7. Modification of carbon fiber surfaces via grafting with Meldrum's acid

    Science.gov (United States)

    Cuiqin, Fang; Jinxian, Wu; Julin, Wang; Tao, Zhang

    2015-11-01

    The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

  8. Modification of carbon fiber surfaces via grafting with Meldrum's acid

    International Nuclear Information System (INIS)

    Cuiqin, Fang; Jinxian, Wu; Julin, Wang; Tao, Zhang

    2015-01-01

    Graphical abstract: - Highlights: • The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated. • The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid. • The relative content of carboxylic groups on carbon fiber surfaces was increased. • The surfaces of carbon fibers neither etched nor generated coating. • Tensile strength of carbon fibers was preserved after grafting reaction. - Abstract: The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

  9. Modification of carbon fiber surfaces via grafting with Meldrum's acid

    Energy Technology Data Exchange (ETDEWEB)

    Cuiqin, Fang; Jinxian, Wu [Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Julin, Wang, E-mail: wjl@mail.buct.edu.cn [Beijing Key Laboratory of Electrochemical Process and Technology for Materials, Beijing University of Chemical Technology, Beijing 100029 (China); Tao, Zhang [Beijing Institute of Ancient Architecture, Beijing 100050 (China)

    2015-11-30

    Graphical abstract: - Highlights: • The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated. • The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid. • The relative content of carboxylic groups on carbon fiber surfaces was increased. • The surfaces of carbon fibers neither etched nor generated coating. • Tensile strength of carbon fibers was preserved after grafting reaction. - Abstract: The mechanism of Meldrum's acid modifying carbon fiber surfaces was investigated in this work. The existing carbonyl groups of carbon fibers were grafted with Meldrum's acid to create carboxylic functionalized surfaces. The surface functionalization effect was detected with X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), atomic force microscopy (AFM), and thermogravimetric analysis (TGA). The XPS results showed that the relative content of carboxylic groups on carbon fiber surfaces was increased from initial 1.41% to 7.84%, however, that of carbonyl groups was decreased from 23.11% to 13.28% after grafting reaction. The SEM, AFM and TGA results indicated that the surfaces of carbon fibers neither etched nor generated coating. The tensile strength of carbon fibers was preserved after grafting reaction according to single fiber tensile strength tests. The fibers were well combined with matrix and the maximal interlaminar shear strength (ILSS) of carbon fiber/epoxy resin composites was sharply increased approximately 74% after functionalization. The effects of acetic acid and sonication on the degree of the surface functionalization were also studied.

  10. Synthesis, crystal structures, and luminescent properties of two series' of new lanthanide (III) amino-carboxylate-phosphonates.

    Science.gov (United States)

    Zhou, Tian-Hua; Yi, Fei-Yan; Li, Pei-Xin; Mao, Jiang-Gao

    2010-02-01

    Hydrothermal reactions of lanthanide(III) chlorides with 4-HOOC-C(6)H(4)-CH(2)NHCH(2)PO(3)H(2) (H(3)L) at different ligand-to-metal (L/M) ratios afforded nine new lanthanide(III) carboxylate-phosphonates with two types of 3D network structures, namely, LnCl(HL)(H(2)O)(2) (Ln = Sm, 1; Eu, 2; Gd, 3; Tb, 4; Dy, 5; Er, 6) and [Ln(2)(HL)(H(2)L)(L)(H(2)O)(2)].4H(2)O (Ln = Nd, 7; Sm, 8; Eu, 9). Compounds 1-6 are isostructural and feature a 3D network in which the LnO(7)Cl polyhedra are interconnected by bridging CPO(3) tetrahedra into 2D inorganic layers parallel to the bc plane. These layers are further cross-linked by organic groups of the carboxylate-phosphonate ligands via the coordination of the carboxylate groups into a pillared-layered architecture. Compounds 7-9 are also isostructural and feature a 3D open-framework composed of 1D lanthanide(III) phosphonate inorganic slabs which are further bridged by organic groups of the carboxylate-phosphonate liagnds via the coordination of the carboxylate groups, forming large 1D tunnels along the b-axis which are filled by lattice water molecules. Luminescent measurements indicate that compounds 2, 4, and 5 show strong emission bands in red, green, and yellow light region, respectively. Magnetic properties of 2, 3, 5, and 7 have also been studied.

  11. Surface structure determination of group 11 metals adsorbed on a rhenium(10 anti 10) surface by low-energy electron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Messahel, Lyria

    2012-11-12

    This thesis deals with the computational surface determination of various long-range ordered phases formed by thin films of copper, silver, and gold adsorbed on the rhenium- (10 anti 10) surface. It is based upon LEED-I,V curves for these phases that were recorded in the course of detailed experimental investigations of the respective films carried out in our group (using techniques such as LEED, MEED, and TPD). In order to solve the intricate puzzle of surface structural analysis, the electron elastic scattering behaviour of the investigated coinage metal phases was calculated using the Erlangen TensErLEED program package. Thereby first a set of theoretical LEED-I,V curves is derived for a guessed reference structure. Subsequently its structural input parameters are varied in a trial-and-error procedure until optimal agreement between experiment and theory is attained. The (1 x 1) phases formed by the deposited metals were tackled first to establish an absolute coverage calibration and to elucidate the respective growth modes on the Re(10 anti 10) surface. In all three cases the (1 x 1) structure is developed best at a coverage {Theta}{sub Cu,Ag,Au}=2 ML=1 BL. Extension of the investigation to experimental I,V curves for higher Cu coverages revealed that this element continues to grow bilayerwise, thereby retaining the Re hcp morphology. Ag, in contrast to Cu and Au, happens not to grow as homogeneously, and the TPD data suggest that Ag films exhibit the so-called simultaneous-multilayer (SM) growth mode. The following analysis of the sub-bilayer coverage range shows that the three systems exhibit considerable differences. While Cu, having a negative lattice misfit compared to Re, shows no long-range ordered superstructures, Ag and Au with a similar positive misfit form a couple of such phases. Ag features both a (1 x 4) phase, stable at ambient temperatures, that upon heating transforms into a c(2 x 2) phase that only exists at elevated temperatures. The

  12. Surface structure determination of group 11 metals adsorbed on a rhenium(10 anti 10) surface by low-energy electron diffraction

    International Nuclear Information System (INIS)

    Messahel, Lyria

    2012-01-01

    This thesis deals with the computational surface determination of various long-range ordered phases formed by thin films of copper, silver, and gold adsorbed on the rhenium- (10 anti 10) surface. It is based upon LEED-I,V curves for these phases that were recorded in the course of detailed experimental investigations of the respective films carried out in our group (using techniques such as LEED, MEED, and TPD). In order to solve the intricate puzzle of surface structural analysis, the electron elastic scattering behaviour of the investigated coinage metal phases was calculated using the Erlangen TensErLEED program package. Thereby first a set of theoretical LEED-I,V curves is derived for a guessed reference structure. Subsequently its structural input parameters are varied in a trial-and-error procedure until optimal agreement between experiment and theory is attained. The (1 x 1) phases formed by the deposited metals were tackled first to establish an absolute coverage calibration and to elucidate the respective growth modes on the Re(10 anti 10) surface. In all three cases the (1 x 1) structure is developed best at a coverage Θ Cu,Ag,Au =2 ML=1 BL. Extension of the investigation to experimental I,V curves for higher Cu coverages revealed that this element continues to grow bilayerwise, thereby retaining the Re hcp morphology. Ag, in contrast to Cu and Au, happens not to grow as homogeneously, and the TPD data suggest that Ag films exhibit the so-called simultaneous-multilayer (SM) growth mode. The following analysis of the sub-bilayer coverage range shows that the three systems exhibit considerable differences. While Cu, having a negative lattice misfit compared to Re, shows no long-range ordered superstructures, Ag and Au with a similar positive misfit form a couple of such phases. Ag features both a (1 x 4) phase, stable at ambient temperatures, that upon heating transforms into a c(2 x 2) phase that only exists at elevated temperatures. The structure

  13. Carboxyl-terminal Truncations of ClC-Kb Abolish Channel Activation by Barttin Via Modified Common Gating and Trafficking*

    Science.gov (United States)

    Stölting, Gabriel; Bungert-Plümke, Stefanie; Franzen, Arne; Fahlke, Christoph

    2015-01-01

    ClC-K chloride channels are crucial for auditory transduction and urine concentration. Mutations in CLCNKB, the gene encoding the renal chloride channel hClC-Kb, cause Bartter syndrome type III, a human genetic condition characterized by polyuria, hypokalemia, and alkalosis. In recent years, several Bartter syndrome-associated mutations have been described that result in truncations of the intracellular carboxyl terminus of hClC-Kb. We here used a combination of whole-cell patch clamp, confocal imaging, co-immunoprecipitation, and surface biotinylation to study the functional consequences of a frequent CLCNKB mutation that creates a premature stop codon at Trp-610. We found that W610X leaves the association of hClC-Kb and the accessory subunit barttin unaffected, but impairs its regulation by barttin. W610X attenuates hClC-Kb surface membrane insertion. Moreover, W610X results in hClC-Kb channel opening in the absence of barttin and prevents further barttin-mediated activation. To describe how the carboxyl terminus modifies the regulation by barttin we used V166E rClC-K1. V166E rClC-K1 is active without barttin and exhibits prominent, barttin-regulated voltage-dependent gating. Electrophysiological characterization of truncated V166E rClC-K1 demonstrated that the distal carboxyl terminus is necessary for slow cooperative gating. Since barttin modifies this particular gating process, channels lacking the distal carboxyl-terminal domain are no longer regulated by the accessory subunit. Our results demonstrate that the carboxyl terminus of hClC-Kb is not part of the binding site for barttin, but functionally modifies the interplay with barttin. The loss-of-activation of truncated hClC-Kb channels in heterologous expression systems fully explains the reduced basolateral chloride conductance in affected kidneys and the clinical symptoms of Bartter syndrome patients. PMID:26453302

  14. Nitrile rubber and carboxylated nitrile rubber resistance to soybean biodiesel

    Directory of Open Access Journals (Sweden)

    Felipe Nunes Linhares

    2018-03-01

    Full Text Available Abstract Biodiesel has been considered a suitable substitute for petroleum diesel, but their chemical composition differs greatly. For this reason, biodiesel interacts differently than petroleum diesel with various materials, including rubbers. Therefore, the resistance of some elastomers should be thoroughly evaluated, specifically those which are commonly used in automotive industry. Nitrile rubber (NBR is widely used to produce vehicular parts that are constantly in contact with fuels. This paper aimed to assess the resistance of carboxylated nitrile rubber (XNBR with 28% of acrylonitrile content to soybean biodiesel in comparison with non-carboxylated nitrile rubber samples, with high and medium acrylonitrile content (33 and 45%. NBR with medium acrylonitrile content showed little resistance to biodiesel. However, carboxylated nitrile rubber even with low acrylonitrile content had similar performance to NBR with high acrylonitrile content.

  15. Properties of the Carboxylate ion exchange resins; Karboxylatjonbytarmassans egenskaper

    Energy Technology Data Exchange (ETDEWEB)

    Allard, Bert; Dario, Maarten [Oerebro Univ. (Sweden); Boren, Hans [Linkoepings Univ. (Sweden); Torstenfelt, Boerje [Swedpower, Stockholm (Sweden); Puigdomenech, Ignasi; Johansson, Claes [Swedish Nuclear Fuel and Waste Management Co., Stockholm (Sweden)

    2002-09-01

    Weakly acidic, carboxylic resin has been selected, together with strong base anion resins, for water purification at the Forsmark 1 and 2 reactors. For the strong (but not the weak) ion exchange resin the Nuclear Power Inspectorate has given permission to dispose the spent resins in the SFR 1 (the Final Repository for Radioactive Operational Waste). This report gives a review of the carboxylic resins and comes to the conclusion that the resins are very stable and that there should not exist any risks for increased leaching of radionuclides from SFR 1 if these resins are disposed (compared to the strong resins)

  16. Biotin Carboxyl Carrier Protein in Barley Chloroplast Membranes

    DEFF Research Database (Denmark)

    Kannangara, C. G.; Jense, C J

    1975-01-01

    Biotin localized in barley chloroplast lamellae is covalently bound to a single protein with an approximate molecular weight of 21000. It contains one mole of biotin per mole of protein and functions as a carboxyl carrier in the acetyl-CoA carboxylase reaction. The protein was obtained by solubil...... by solubilization of the lamellae in phenol/acetic acid/8 M urea. Feeding barley seedlings with [14C]-biotin revealed that the vitamin is not degraded into respiratory substrates by the plant, but is specifically incorporated into biotin carboxyl carrier protein....

  17. Analytical study of zirconium and hafnium α-hydroxy carboxylates

    International Nuclear Information System (INIS)

    Terra, V.R.

    1991-01-01

    The analytical study of zirconium and hafnium α-hydroxy carboxylates was described. For this purpose dl-mandelic, dl-p-bromo mandelic, dl-2-naphthyl glycolic, and benzilic acids were prepared. These were used in conjunction with glycolic, dl-lactic, dl-2-hydroxy isovaleric, dl-2-hydroxy hexanoic, and dl-2-hydroxy dodecanoic acids in order to synthesize the zirconium(IV) and hafnium(IV) tetrakis(α-hydroxy carboxylates). The compounds were characterized by melting point determination, infrared spectroscopy, thermogravimetric analysis, calcination to oxides and X-ray diffractometry by the powder method. (C.G.C)

  18. The neural cell adhesion molecule L1 is distinct from the N-CAM related group of surface antigens BSP-2 and D2

    DEFF Research Database (Denmark)

    Faissner, A; Kruse, J; Goridis, C

    1984-01-01

    The neural cell adhesion molecule L1 and the group of N-CAM related molecules, BSP-2 and D2 antigen, are immunochemically distinct molecular species. The two groups of surface molecules are also functionally distinct entities, since inhibition of Ca2+-independent adhesion among early post-natal m...

  19. 6-(Hex-5-enyloxynaphthalene-2-carboxylic acid

    Directory of Open Access Journals (Sweden)

    Md. Lutfor Rahman

    2014-06-01

    Full Text Available The asymmetric unit of the title compound, C17H18O3, comprises three independent molecules with similar geometries. In each molecule, the carbonyl group is twisted away from the napthalene ring system, making dihedral angles of 1.0 (2, 1.05 (19° and 1.5 (2°. The butene group in all three molecules are disordered over two sets of sites, with a refined occupancy ratio of 0.664 (6:0.336 (6. In the crystal, molecules are oriented with respect to their carbonyl groups, forming head-to-head dimers via O—H...O hydrogen bonds. Adjacent dimers are further interconnected by C—H...O hydrogen bonds into chains along the a-axis direction. The crystal structure is further stabilized by weak C—H...π interactions.

  20. Probing Interaction Between Platinum Group Metal (PGM) and Non-PGM Support Through Surface Characterization and Device Performance

    Science.gov (United States)

    Saha, Shibely

    High cost and limited abundance of Platinum (Pt) have hindered effective commercialization of Proton Exchange Membrane Fuel Cell and Electrolyzer. Efforts have been undertaken to reduce precious group metal (PGM) requirement for these devices without compromising the activity of the catalyst by using transition metal carbides (TMC) as non-PGM support thanks to their similar electronic and geometric structures as Pt. In this work Mo2C was selected as non-PGM support and Pt was used as the PGM of interest. We hypothesize that the hollow nanotube morphology of Mo2C support combined with Pt nano particles deposited on it via atomic layer deposition (ALD) technique would allow increased interaction between them which may increase the activity of Pt and Mo2C as well as maximize the Pt active surface area. Specifically, a rotary ALD equipment was used to grow Pt particles from atomic level to 2--3 nanometers by simply adjusting number of ALD cycles in order to probe the interaction between the deposited Pt nanoparticles and Mo2C nanotube support. Interaction between the Pt and Mo2 C was analyzed via surface characterization and electrochemical characterization. Interaction between Pt and Mo2C arises due to the lattice mismatch between Pt and Mo2C as well as electron migration between them. Lattice spacing analysis using high resolution transmission electron microscopy (HRTEM) images, combined with Pt binding energy shift in XPS results, clearly showed strong bonding between Pt nanoparticles and the Mo2C nanotube support in all the resultant Pt/Mo2C samples. We postulate that this strong interaction is responsible for the significantly enhanced durability observed in our constant potential electrolysis (CPE) and accelerated degradation testing (ADT). Of the three samples from different ALD cycles (15, 50 and 100), Mo2C nanotubes modified by 50 (1.07 wt% Pt loading) and 100 cycles (4.4 wt% Pt) of Pt deposition, showed higher HER and HOR activity per Pt mass than commercial

  1. Plasma Surface Modification for Immobilization of Bone Morphogenic Protein-2 on Polycaprolactone Scaffolds

    Science.gov (United States)

    Kim, Byung Hoon; Myung, Sung Woon; Jung, Sang Chul; Ko, Yeong Mu

    2013-11-01

    The immobilization of recombinant human bone formation protein-2 (rhBMP-2) on polycaprolactone (PCL) scaffolds was performed by plasma polymerization. RhBMP-2, which induces osteoblast differentiation in various cell types, is a growth factor that plays an important role in bone formation and repair. The surface of the PCL scaffold was functionalized with the carboxyl groups of plasma-polymerized acrylic acid (PPAA) thin films. Plasma polymerization was carried out at a discharge power of 60 W at an acrylic acid flow rate of 7 sccm for 5 min. The PPAA thin film exhibited moderate hydrophilic properties and possessed a high density of carboxyl groups. Carboxyl groups and rhBMP-2 on the PCL scaffolds surface were identified by attenuated total reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, respectively. The alkaline phosphatase activity assay showed that the rhBMP-2 immobilized PCL scaffold increased the level of MG-63 cell differentiation. Plasma surface modification for the preparation of biomaterials, such as biofunctionalized polymer scaffolds, can be used for the binding of bioactive molecules in tissue engineering.

  2. Low-Dose Daily Intake of Vitamin K(2) (Menaquinone-7) Improves Osteocalcin γ-Carboxylation: A Double-Blind, Randomized Controlled Trials.

    Science.gov (United States)

    Inaba, Naoko; Sato, Toshiro; Yamashita, Takatoshi

    2015-01-01

    Vitamin K is essential for bone health, but the effects of low-dose vitamin K intake in Japanese subjects remain unclear. We investigated the effective minimum daily menaquinone-7 dose for improving osteocalcin γ-carboxylation. Study 1 was a double-blind, randomized controlled dose-finding trial; 60 postmenopausal women aged 50-69 y were allocated to one of four dosage group and consumed 0, 50, 100, or 200 μg menaquinone-7 daily for 4 wk, respectively, with a controlled diet in accordance with recommended daily intakes for 2010 in Japan. Study 2 was a double-blind, randomized placebo-controlled trial based on the results of Study 1; 120 subjects aged 20-69 y were allocated to the placebo or MK-7 group and consumed 0 or 100 μg menaquinone-7 daily for 12 wk, respectively. In both studies, circulating carboxylated osteocalcin and undercarboxylated osteocalcin were measured. The carboxylated osteocalcin/undercarboxylated osteocalcin ratio decreased significantly from baseline in the 0 μg menaquinone-7 group, in which subjects consumed the recommended daily intake of vitamin K with vitamin K1 and menaquinone-4 (Study 1). Menaquinone-7 increased the carboxylated osteocalcin/undercarboxylated osteocalcin ratio dose dependently, and significant effects were observed in both the 100 and 200 μg groups compared with the 0 μg group. Undercarboxylated osteocalcin concentrations decreased significantly, and the carboxylated osteocalcin/undercarboxylated osteocalcin ratio increased significantly in the 100 μg menaquinone-7 group compared with the placebo group (Study 2). Daily menaquinone-7 intake ≥100 μg was suggested to improve osteocalcin γ-carboxylation.

  3. Boron-Catalyzed N-Alkylation of Amines using Carboxylic Acids.

    Science.gov (United States)

    Fu, Ming-Chen; Shang, Rui; Cheng, Wan-Min; Fu, Yao

    2015-07-27

    A boron-based catalyst was found to catalyze the straightforward alkylation of amines with readily available carboxylic acids in the presence of silane as the reducing agent. Various types of primary and secondary amines can be smoothly alkylated with good selectivity and good functional-group compatibility. This metal-free amine alkylation was successfully applied to the synthesis of three commercial medicinal compounds, Butenafine, Cinacalcet. and Piribedil, in a one-pot manner without using any metal catalysts. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. A temperature induced ferrocene–ferrocenium interconversion in a ferrocene functionalized μ3-O chromium carboxylate

    International Nuclear Information System (INIS)

    Mereacre, Valeriu; Schlageter, Martin; Powell, Annie K.

    2015-01-01

    The infrared spectra and 57 Fe Mössbauer measurements of a ferrocenecarboxylate functionalized {Cr 3 O} complex in solid state are reported. It was established that conjugation of ferrocene Cp orbitals with the π orbitals of the adjacent carboxylic group stabilizes the trapped mixed-valence state leading to an intriguing coexistence of ferrocene and ferrocenium species giving rise to a new type of compound showing valence tautomerism in the solid state. - Highlights: • A stabilized ferrocene trapped mixed-valence state is reported. • New type of compound showing valence tautomerism in solid state. • A thermally induced electron transfer and a mixed-valence state near room temperature

  5. Synthesis of first row transition metal carboxylate complexes by ring ...

    Indian Academy of Sciences (India)

    tion of pyromellitic dianhydride with methanol and ring opening of pyromellitic dianhydride takes place. The corresponding carboxylate complex formed dur- ing the process can be crystallised by adding biden- tate nitrogen donor ligands such as 1,10-phenanthroline or 2,2 - bipyridine.20 From the reaction with 1,10-.

  6. Kinetics study of thermal decomposition of calcium carboxylate salts

    International Nuclear Information System (INIS)

    Landoll, Michael P.; Holtzapple, Mark T.

    2013-01-01

    The MixAlco™ process ferments lignocellulosic biomass to carboxylate salts that are thermally decomposed into ketones, which are then chemically converted to a wide variety of chemicals and fuels. To perform these decompositions, suitable reaction models are necessary to properly design, scale, and optimize commercial reactors. For three salt types (calcium acetate, and two types of mixed calcium carboxylate salts), activation energy was determined using three isoconversional methods that employed TGA curves at different heating rates. For all three salt types, activation energy varied significantly with conversion. The average activation energy for calcium acetate was 556.75 kJ mol −1 , and the activation energies for the two mixed calcium carboxylate salts were 232.87, and 176.55 kJ mol −1 . In addition, three functions of conversion were employed to see which one best modeled the experimental data. The Sestak–Berggren model provides the best universal fit for all three salt types. -- Highlights: •Calcium carboxylate salts from fermentation broth thermally decompose to ketones. •Activation energy varies with conversion for all three salt types. •Sestak–Berggren model provides best fit overall for all three salt types

  7. Kinetics study of thermal decomposition of sodium carboxylate salts

    International Nuclear Information System (INIS)

    Landoll, Michael P.; Holtzapple, Mark T.

    2012-01-01

    The MixAlco™ process ferments lignocellulosic biomass to carboxylate salts that are thermally decomposed into ketones, which are then chemically converted to a wide variety of chemicals and fuels. To perform these decompositions, suitable reaction models are necessary to properly design, scale, and optimize commercial reactors. For three salt types (sodium acetate, and two types of mixed sodium carboxylate salts), activation energy was determined using three isoconversional methods that employed TGA curves at different heating rates. For all three salt types, activation energy varied significantly with conversion. The average activation energy for sodium acetate was 226.65 kJ/mol, and the activation energies for the two mixed sodium carboxylate salts were 195.61, and 218.18 kJ/mol. In addition, three functions of conversion were employed to see which one best modeled the experimental data. The Sestak-Berggren model fits all three salt types best. -- Highlights: ► Sodium carboxylate salts from fermentation broth thermally decompose to ketones. ► Activation energy varies with conversion for all three salt types. ► Sestak-Berggren model provides best fit for all three salt types.

  8. catalysed ortho-carboxylation of acetanilide with CO

    Indian Academy of Sciences (India)

    Abstract. The mechanism of palladium(II)-catalysed carboxylation of acetanilide with CO has been investi- gated using density functional theory calculation done at the B3LYP/6-31G(d, p)(SDD for Pd) level of theory. Solvent effects on these reactions have been explored by calculation that included a polarizable continuum.

  9. Determination of Carboxylic Acids and Water-soluble Inorganic Ions ...

    African Journals Online (AJOL)

    Atmospheric aerosol samples of PM2.5 and PM10 were collected in April–May 2011 from a rural site in Tanzania and analyzed for water-soluble inorganic ions and low molecular weight carboxylic acids using ion chromatography. PM2.5 and PM10 low-volume samplers with quartz fibre filters were deployed and aerosol ...

  10. Photodecarboxylative Cyclizations of ω-Phthalimido-para-phenoxy Carboxylates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ae Rhan; Lee, Younsik; Yoo, Dong Jin [Chonbuk National Univ., Jeonju (Korea, Republic of); Cho, Hyunseung [Seonam Univ., Namwon (Korea, Republic of)

    2012-10-15

    The chemistry of electronically-excited phthalimides is dictated by electron and/or hydrogen transfer reactions. The photochemistry of phthalimides has been intensively studied, and numerous synthetically useful transformations with high chemical and quantum yields have been developed. 3 Among the synthetic applications, intra- and intermolecular photodecarboxylation (PDC) of ω-phthalimidoalkyl carboxylates has been developed by Griesbeck and coworkers as a versatile pathway to medium- and large-ring heterocycles. Model reactions were further realized on macro- and micro-scales. We recently described PDC cyclizations of ω-phthalimidoalkynoates to produce macrocyclic alkynes with ring-sizes up to 17. In recent study, we expanded the portfolio of this reaction and investigated the photochemistry of related aryl-linked phthalimides in Scheme 1. Based on these approaches, we demonstrated that ω-phthalimido-ortho/meta-phenoxy carboxylates undergo efficient PDC cyclizations. While the yields of ω-phthalimido-ortho-phenoxy carboxylates steadily decreased with increasing chain-length and the maximum yield of the 6-membered product was obtained in 75%, the yields of meta-phenoxy carboxylates steadily increased with increasing chain-length and the extended 16-membered product was subsequently obtained in 48% yield.

  11. Cloning of phenazine carboxylic acid genes of Fusarium fujikuroi ...

    African Journals Online (AJOL)

    STORAGESEVER

    2010-03-08

    Mar 8, 2010 ... genetic modification can improve the efficacy of biological control agents (Van Loon, 1998). Bacterial secondary ... WCS358r was modified to produce the antifungal com- pound phenazine-1-carboxylic acid (PCA) ( ..... control of Rhizoctonia solani in tomato. J. Biotechnol. 6: 115-127. Raaijmakers JM ...

  12. Light dependence of carboxylation capacity for C3 photosynthesis models

    Science.gov (United States)

    Photosynthesis at high light is often modelled by assuming limitation by the maximum capacity of Rubisco carboxylation at low carbon dioxide concentrations, by electron transport capacity at higher concentrations, and sometimes by triose-phosphate utilization rate at the highest concentrations. Pho...

  13. Dimerization of Carboxylic Acids: An Equation of State Approach

    DEFF Research Database (Denmark)

    Tsivintzelis, Ioannis; Kontogeorgis, Georgios; Panayiotou, Costas

    2017-01-01

    The association term of the nonrandom hydrogen bonding theory, which is an equation of state model, is extended to describe the dimerization of carboxylic acids in binary mixtures with inert solvents and in systems of two different acids. Subsequently, the model is applied to describe the excess...

  14. Engineering Copper Carboxylate Functionalities on Water Stable Metal–Organic Frameworks for Enhancement of Ammonia Removal Capacities

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Jayraj N.; Garcia-Gutierrez, Erika Y.; Moran, Colton M.; Deneff, Jacob I.; Walton, Krista S.

    2017-02-02

    Functionalization of copper carboxylate groups on a series of UiO-66 metal organic framework (MOF) analogues and their corresponding impact on humid and dry ammonia adsorption behavior were studied. Relative locations of possible carboxylic acid binding sites for copper on the MOF analogues were varied on ligand and missing linker defect sites. Materials after copper incorporation exhibited increased water vapor and ammonia affinity during isothermal adsorption and breakthrough experiments, respectively. The introduction of copper markedly increased ammonia adsorption capacities for all adsorbents possessing carboxyl binding sites. In particular, the new MOF UiO-66-(COOCu)2 displayed the highest ammonia breakthrough capacities of 6.38 and 6.84 mmol g–1 under dry and humid conditions, respectively, while retaining crystallinity and porosity. Relative carboxylic acid site locations were also found to impact sorbent stability, as missing linker defect functionalized materials degraded under humid conditions after copper incorporation. Postsynthetic metal insertion provides a method for adding sites that are analogous to open metal sites while maintaining good structural stability.

  15. Carboxylate-intercalated layered double hydroxides aged under microwave-hydrothermal treatment

    International Nuclear Information System (INIS)

    Benito, P.; Labajos, F.M.; Mafra, L.; Rocha, J.; Rives, V.

    2009-01-01

    Carboxylate-intercalated (terephthalate, TA and oxalate, ox) layered double hydroxides (LDHs) are aged under a microwave-hydrothermal treatment. The influence of the nature of the interlayer anion during the ageing process is studied. Characterization results show that the microwave-hydrothermal method can be extended to synthesize LDHs with anions different than carbonate, like TA. LDH-TA compounds are stable under microwave irradiation for increasing periods of time and the solids show an improved order both in the layers and in the interlayer region as evidenced by powder X-ray diffraction (PXRD), 27 Al MAS NMR and FT-IR spectroscopy. Furthermore, cleaning of the surface through removal of some organic species adsorbed on the surface of the particles also occurs during the microwave-hydrothermal treatment. Conversely, although the expected increase in crystallinity is observed in LDH-ox samples, the side-reaction between Al 3+ and ox is also enhanced under microwave irradiation, and a partial destruction of the structure takes place with an increase in the M 2+ /M 3+ ratio and consequent modification of the cell parameters. - Graphical Abstract: The influence of the nature of the interlayer anion during the ageing process of carboxylate-intercalated (TA and ox) hydrotalcite-like compounds (HTlcs) is studied. Well crystallized for TA-containing compounds were obtained. However, the non-desired side-reaction of ox with the aluminum of the layers is enhanced by the microwaves and a partial destruction of the structure takes place

  16. New photoresponsive (meth)acrylate (co)polymers containing azobenzene pendant sidegroups with carboxylic and dimethylamino substituents .2. Synthesis and characterization of polymers and copolymers

    NARCIS (Netherlands)

    Haitjema, HJ; Buruma, R; VanEkenstein, GORA; Tan, YY; Challa, G

    1996-01-01

    The title (co)polymers, used for our investigations on their photoresponsive behaviour were obtained by free radical (co)polymerization. The monomer was either an acrylate or a methacrylate to which an azobenzene group, modified with a para-placed dimethylamino or a carboxylic pendant group, was

  17. Structural and Functional Models of Non-Heme Iron Enzymes : A Study of the 2-His-1-Carboxylate Facial Triad Structural Motif

    NARCIS (Netherlands)

    Bruijnincx, P.C.A.

    2007-01-01

    The structural and functional modeling of a specific group of non-heme iron enzymes by the synthesis of small synthetic analogues is the topic of this thesis. The group of non-heme iron enzymes with the 2-His-1-carboxylate facial triad has recently been established as a common platform for the

  18. Carbon Nanotube Web with Carboxylated Polythiophene "Assist" for High-Performance Battery Electrodes.

    Science.gov (United States)

    Kwon, Yo Han; Park, Jung Jin; Housel, Lisa M; Minnici, Krysten; Zhang, Guoyan; Lee, Sujin R; Lee, Seung Woo; Chen, Zhongming; Noda, Suguru; Takeuchi, Esther S; Takeuchi, Kenneth J; Marschilok, Amy C; Reichmanis, Elsa

    2018-04-24

    A carbon nanotube (CNT) web electrode comprising magnetite spheres and few-walled carbon nanotubes (FWNTs) linked by the carboxylated conjugated polymer, poly[3-(potassium-4-butanoate) thiophene] (PPBT), was designed to demonstrate benefits derived from the rational consideration of electron/ion transport coupled with the surface chemistry of the electrode materials components. To maximize transport properties, the approach introduces monodispersed spherical Fe 3 O 4 (sFe 3 O 4 ) for uniform Li + diffusion and a FWNT web electrode frame that affords characteristics of long-ranged electronic pathways and porous networks. The sFe 3 O 4 particles were used as a model high-capacity energy active material, owing to their well-defined chemistry with surface hydroxyl (-OH) functionalities that provide for facile detection of molecular interactions. PPBT, having a π-conjugated backbone and alkyl side chains substituted with carboxylate moieties, interacted with the FWNT π-electron-rich and hydroxylated sFe 3 O 4 surfaces, which enabled the formation of effective electrical bridges between the respective components, contributing to efficient electron transport and electrode stability. To further induce interactions between PPBT and the metal hydroxide surface, polyethylene glycol was coated onto the sFe 3 O 4 particles, allowing for facile materials dispersion and connectivity. Additionally, the introduction of carbon particles into the web electrode minimized sFe 3 O 4 aggregation and afforded more porous FWNT networks. As a consequence, the design of composite electrodes with rigorous consideration of specific molecular interactions induced by the surface chemistries favorably influenced electrochemical kinetics and electrode resistance, which afforded high-performance electrodes for battery applications.

  19. Studies on carboxylated graphene oxide incorporated polyetherimide mixed matrix ultrafiltration membranes

    Energy Technology Data Exchange (ETDEWEB)

    Kaleekkal, Noel Jacob, E-mail: noeljacob89@gmail.com [Membrane Laboratory, Department of Chemical Engineering, ACT, Anna University, Chennai, 600025 (India); Thanigaivelan, A., E-mail: thanichemstar@gmail.com [Membrane Laboratory, Department of Chemical Engineering, ACT, Anna University, Chennai, 600025 (India); Rana, Dipak, E-mail: rana@uottawa.ca [Department of Chemical and Biological Engineering, University of Ottawa, 161 Louis Pasteur Private, Ottawa, Ontario, K1N 6N5 (Canada); Mohan, D., E-mail: mohantarun@gmail.com [Membrane Laboratory, Department of Chemical Engineering, ACT, Anna University, Chennai, 600025 (India)

    2017-01-15

    In this work the graphene oxide prepared by the modified Hummers’ method was effectively carboxylated. These carboxylated graphene oxide (c-GO) microsheets was characterized by X-ray diffraction analysis, Raman shift, zeta potential, and their morphology was observed using a high resolution scanning/transmission electron microscopy. Polyetherimide mixed matrix membranes (MMMs) were fabricated by the non-solvent induced phase separation technique with varying concentration of this microsheet. The presence of these microsheets on the membrane surface was confirmed by Fourier transform infrared spectroscopy, Raman spectroscopy and could also be confirmed visually by optical images. The membranes were further characterized; they showed a greater water flux, higher porosity, and sufficient thermal stability. Incorporation of these microsheets improved the hydrophilicity of the membrane confirmed by the lower contact angle values, which in turn explained the lower interfacial free energy, the increase in work of adhesion, the higher solid-vapor free energy and the spreading coefficient. Membranes loaded with 0.3 wt% of c-GO showed a flux recovery of 94% and only a small flux decline even after 180 min of filtration of humic acid (HA) solution. The efficiency of these membranes in removal of HA, toxic metal ions was also investigated. The bacterial anti-adhesion property of c-GO in the membranes was also explored using Escherichia coli, as a model bio-foulant. The charge of the microsheets and their unique architecture imparts higher hydrophilicity and greater fouling resistance along with improved permeation flux when incorporated into the polymer matrix. - Highlights: • Novel membranes by incorporating carboxylated GO into polyetherimide matrix. • Modified membranes exhibited greater porosity, flux and high humic acid rejection. • Nanoplatelets improved the flux recovery ratio to >94%. • Liquid phase polymer based retention utilized for toxic heavy metal

  20. Tuning metal–carboxylate coordination in crystalline metal–organic frameworks through surfactant media

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Junkuo [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Ye, Kaiqi [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012 (China); He, Mi [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Xiong, Wei-Wei; Cao, Wenfang; Lee, Zhi Yi [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Wang, Yue [State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun 130012 (China); Wu, Tom [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Huo, Fengwei [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore); Liu, Xiaogang [Department of Chemistry, National University of Singapore, Singapore 117543 (Singapore); Institute of Materials Research Engineering, Agency for Science, Technology and Research, Singapore 117602 (Singapore); Zhang, Qichun, E-mail: qczhang@ntu.edu.sg [School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798 (Singapore)

    2013-10-15

    Although it has been widely demonstrated that surfactants can efficiently control the size, shape and surface properties of micro/nanocrystals of metal–organic frameworks (MOFs) due to the strong interactions between surfactants and crystal facets of MOFs, the use of surfactants as reaction media to grow MOF single crystals is unprecedented. In addition, compared with ionic liquids, surfactants are much cheaper and can have multifunctional properties such as acidic, basic, neutral, cationic, anionic, or even block. These factors strongly motivate us to develop a new synthetic strategy: growing crystalline MOFs in surfactants. In this report, eight new two-dimensional (2D) or three-dimensional (3D) MOFs have been successfully synthesized in an industrially-abundant and environmentally-friendly surfactant: polyethylene glycol-200 (PEG-200). Eight different coordination modes of carboxylates, ranging from monodentate η{sup 1} mode to tetra-donor coordination µ{sub 3}-η{sup 1}:η{sup 2}:η{sup 1} mode, have been founded in our research. The magnetic properties of Co-based MOFs were investigated and MOF NTU-Z6b showed a phase transition with a Curie temperature (T{sub c}) at 5 K. Our strategy of growing crystalline MOFs in surfactant could offer exciting opportunities for preparing novel MOFs with diverse structures and interesting properties. - Graphical abstract: Surfactants have been used as reaction media to grow MOF single crystals for the first time. Eight new two-dimensional or three-dimensional MOFs were successfully synthesized in surfactant polyethylene glycol-200 (PEG-200). Coordination modes of carboxylates up to eight were founded. Our strategy of growing crystalline MOFs in surfactant could offer exciting opportunities for preparing novel MOFs with diverse structures and interesting properties. Display Omitted - Highlights: • Surfactant-thermal synthesis of crystalline metal–organic frameworks. • Eight new 2-D or 3-D metal–organic frameworks

  1. First principles-based adsorption comparison of group IV elements (C, Si, Ge, and Sn) on Au(111)/Ag(111) surface

    International Nuclear Information System (INIS)

    Chakraborty, Sudip; Rajesh, Ch.

    2012-01-01

    We have reported a first-principle investigation of the structural properties of monomer and dimer for group IV elements (C, Si, Ge, and Sn) adsorbed on the Au(111) and Ag(111) surfaces. The calculations were performed by means of a plane wave based pseudopotential method under the framework of density functional theory. The results reveal the preference of adatom to be adsorbed on the hexagonal closed packed site of the metal (111) surfaces with strong binding energy. The structures introduce interlayer forces in the adsorbate. The strong bonding with the surface atoms is a result of p–d hybridization. The adsorption energy follows a sequence as one goes down in the group IV elements which imply that the interaction of the group IV elements with Au/Ag is decreasing as the atomic number increases.

  2. 40 CFR 721.4663 - Fluorinated carboxylic acid alkali metal salts.

    Science.gov (United States)

    2010-07-01

    ... Specific Chemical Substances § 721.4663 Fluorinated carboxylic acid alkali metal salts. (a) Chemical... fluorinated carboxylic acid alkali metal salts (PMNs P-95-979/980/981) are subject to reporting under this... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Fluorinated carboxylic acid alkali...

  3. CsF-promoted carboxylation of aryl(hetaryl) terminal alkynes with atmospheric CO_2 at room temperature

    International Nuclear Information System (INIS)

    Yu, B.; Yang, Z.Z.; Zhao, Y.F.; Zhang, H.Y.; Yang, P.; Gao, X.; Liu, Z.M.

    2017-01-01

    A CsF-promoted carboxylation of aryl(hetaryl) terminal alkynes with atmospheric CO_2 in the presence of trimethylsilylacetylene was developed to give functionalized propiolic acid products at room temperature. A wide range of propiolic acids bearing functional groups was successfully obtained in good to excellent yields. Mechanistic studies demonstrate that in the carboxylation process the alkynyl-silane intermediate was first in situ generated, which was then trapped by CO_2, giving rise to the corresponding functionalized propiolic acids after acidification. The advantages of this approach include avoiding use of transition-metal catalysts, wide substrate scope together with excellent functional group tolerance, ambient conditions and a facile work-up procedure. (authors)

  4. Enhanced dispersion stability and mobility of carboxyl-functionalized carbon nanotubes in aqueous solutions through strong hydrogen bonds

    International Nuclear Information System (INIS)

    Bahk, Yeon Kyoung; He, Xu; Gitsis, Emmanouil; Kuo, Yu-Ying; Kim, Nayoung; Wang, Jing

    2015-01-01

    Dispersion of carbon nanotubes has been heavily studied due to its importance for their technical applications, toxic effects, and environmental impacts. Common electrolytes, such as sodium chloride and potassium chloride, promote agglomeration of nanoparticles in aqueous solutions. On the contrary, we discovered that acetic electrolytes enhanced the dispersion of multi-walled carbon nanotubes (MWCNTs) with carboxyl functional group through the strong hydrogen bond, which was confirmed by UV–Vis spectrometry, dispersion observations and aerosolization-quantification method. When concentrations of acetate electrolytes such as ammonium acetate (CH 3 CO 2 NH 4 ) and sodium acetate (CH 3 CO 2 Na) were lower than 0.03 mol per liter, MWCNT suspensions showed better dispersion and had higher mobility in porous media. The effects by the acetic environment are also applicable to other nanoparticles with the carboxyl functional group, which was demonstrated with polystyrene latex particles as an example

  5. Enhanced dispersion stability and mobility of carboxyl-functionalized carbon nanotubes in aqueous solutions through strong hydrogen bonds

    Energy Technology Data Exchange (ETDEWEB)

    Bahk, Yeon Kyoung; He, Xu; Gitsis, Emmanouil; Kuo, Yu-Ying [ETH Zurich, Institute of Environmental Engineering (Switzerland); Kim, Nayoung [EMPA, Building Energy Materials and Components (Switzerland); Wang, Jing, E-mail: jing.wang@ifu.baug.ethz.ch [ETH Zurich, Institute of Environmental Engineering (Switzerland)

    2015-10-15

    Dispersion of carbon nanotubes has been heavily studied due to its importance for their technical applications, toxic effects, and environmental impacts. Common electrolytes, such as sodium chloride and potassium chloride, promote agglomeration of nanoparticles in aqueous solutions. On the contrary, we discovered that acetic electrolytes enhanced the dispersion of multi-walled carbon nanotubes (MWCNTs) with carboxyl functional group through the strong hydrogen bond, which was confirmed by UV–Vis spectrometry, dispersion observations and aerosolization-quantification method. When concentrations of acetate electrolytes such as ammonium acetate (CH{sub 3}CO{sub 2}NH{sub 4}) and sodium acetate (CH{sub 3}CO{sub 2}Na) were lower than 0.03 mol per liter, MWCNT suspensions showed better dispersion and had higher mobility in porous media. The effects by the acetic environment are also applicable to other nanoparticles with the carboxyl functional group, which was demonstrated with polystyrene latex particles as an example.

  6. A Convenient One-Pot Method for the Synthesis of N-Methoxy-N-methyl Amides from Carboxylic Acids

    International Nuclear Information System (INIS)

    Kim, Joong Gon; Jang, Doo Ok

    2010-01-01

    We have developed a mild and convenient method for one-pot synthesis of Weinreb amides from carboxylic acids. The process is general for the preparation of Weinreb amides from a variety of carboxylic acids. The reaction was also applicable to the preparation of α-amino Weinreb amides and proceeded without deprotection of the N-Fmoc protecting group or racemization of the stereogenic centers. N-Methoxy-N-methyl amides, or Weinreb amides, have been widely used as versatile synthetic intermediates in organic syntheses. These amides serve as excellent acylating agents for organolithium or organomagnesium reagents and as robust aldehyde group equivalents. The utility of Weinreb amides has been extended to the preparation of N-protected amino aldehydes, useful intermediates for many chemoselective transformations in peptide chemistry

  7. Proton-conducting membranes based on benzimidazole-containing sulfonated poly(ether ether ketone) compared with their carboxyl acid form

    Energy Technology Data Exchange (ETDEWEB)

    Li, Hongtao; Wu, Jing; Zhao, Chengji; Zhang, Gang; Zhang, Yang; Shao, Ke; Xu, Dan; Lin, Haidan; Han, Miaomiao; Na, Hui [Alan G MacDiarmid Institute, College of Chemistry, Jilin University, Changchun 130012 (China)

    2009-10-15

    A series of sulfonated poly(ether ether ketone) containing pendant carboxyl (C-SPEEKs) have been synthesized using a nucleophilic polycondesation reaction. A condensation reaction between 1,2-diaminobenzene and carboxyl resulted in a new series of copolymers containing benzimidazole groups (SPEEK-BIms). The expected structures of the sulfonated copolymers are confirmed by {sup 1}H NMR. The dependence of ion exchange capacity, water uptake, proton conductivity and methanol diffusion coefficient of SPEEK-BIm membranes has been studied and compared with their carboxyl acid form. The results suggest that the introduction of benzimidazole groups may be responsible for many excellent properties of the membranes for fuel cell. It is noticeable that the markedly improved oxidative stability is benefit for the application of membrane. (author)

  8. High performance flexible pH sensor based on carboxyl-functionalized and DEP aligned SWNTs

    International Nuclear Information System (INIS)

    Liu, Lu; Shao, Jinyou; Li, Xiangming; Zhao, Qiang; Nie, Bangbang; Xu, Chuan; Ding, Haitao

    2016-01-01

    Highlights: • The flexible chemiresistive pH sensor based on two-terminal microsensors eliminating the need for a reference electrode, is simple in structure and can be fabricated on a variety of substrates such as PET, PI and PVC. • SWNTs as an ideal one dimensional material are carboxyl-functionalized to make the pH sensor show high sensitivity and outstanding flexibility for practical applications. • DEP technique is used to manipulate and position SWNTs into appropriate locations and desired formations to improve the metal-nanotube interface and highly rapid detection of pH value, resulting in better overall device performance. • Mechanical bendability of the pH sensor, which arises from the combination of flexible PET substrates and SWNTs, offer a significant improvement for applications that are difficult or impossible to achieve with traditional sensors on rigid substrates. - Abstract: The detection and control of the pH is very important in many biomedical and chemical reaction processes. A miniaturized flexible pH sensor that is light weight, robust, and conformable is very important in many applications, such as multifunctional lab-on-a-chip systems or wearable biomedical devices. In this work, we demonstrate a flexible chemiresistive pH sensor based on dielectrophoresis (DEP) aligned carboxyl-functionalized single-walled carbon nanotubes (SWNTs). Decorated carboxyl groups can react with hydrogen (H"+) and hydroxide (OH"−) ions, enabling the sensor to be capable of sensing the pH. DEP is used to deposit well-organized and highly aligned SWNTs in desired locations, which improves the metal-nanotube interface and highly rapid detection of the pH, resulting in better overall device performance. When pH buffer solutions are dropped onto such SWNTs, the H"+ and OH"− ions caninteract with the carboxyl groups and affect the generation of holes and electrons in the SWNTs, leading to resistance variations in the SWNTs. The results shows that the

  9. High performance flexible pH sensor based on carboxyl-functionalized and DEP aligned SWNTs

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Lu; Shao, Jinyou, E-mail: jyshao@mail.xjtu.edu.cn; Li, Xiangming; Zhao, Qiang; Nie, Bangbang; Xu, Chuan; Ding, Haitao

    2016-11-15

    Highlights: • The flexible chemiresistive pH sensor based on two-terminal microsensors eliminating the need for a reference electrode, is simple in structure and can be fabricated on a variety of substrates such as PET, PI and PVC. • SWNTs as an ideal one dimensional material are carboxyl-functionalized to make the pH sensor show high sensitivity and outstanding flexibility for practical applications. • DEP technique is used to manipulate and position SWNTs into appropriate locations and desired formations to improve the metal-nanotube interface and highly rapid detection of pH value, resulting in better overall device performance. • Mechanical bendability of the pH sensor, which arises from the combination of flexible PET substrates and SWNTs, offer a significant improvement for applications that are difficult or impossible to achieve with traditional sensors on rigid substrates. - Abstract: The detection and control of the pH is very important in many biomedical and chemical reaction processes. A miniaturized flexible pH sensor that is light weight, robust, and conformable is very important in many applications, such as multifunctional lab-on-a-chip systems or wearable biomedical devices. In this work, we demonstrate a flexible chemiresistive pH sensor based on dielectrophoresis (DEP) aligned carboxyl-functionalized single-walled carbon nanotubes (SWNTs). Decorated carboxyl groups can react with hydrogen (H{sup +}) and hydroxide (OH{sup −}) ions, enabling the sensor to be capable of sensing the pH. DEP is used to deposit well-organized and highly aligned SWNTs in desired locations, which improves the metal-nanotube interface and highly rapid detection of the pH, resulting in better overall device performance. When pH buffer solutions are dropped onto such SWNTs, the H{sup +} and OH{sup −} ions caninteract with the carboxyl groups and affect the generation of holes and electrons in the SWNTs, leading to resistance variations in the SWNTs. The results

  10. Dielectric barrier discharge plasma treatment of cellulose nanofibre surfaces

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Madsen, Bo; Berglund, Linn

    2017-01-01

    on the nanofibre surface. Ultrasonic irradiation further enhanced the wetting and oxidation of the nanofibre coating. Scanning electron microscopic observations showed skeleton-like features on the plasma-treated surface, indicating preferential etching of weaker domains, such as low-molecular weight domains......Dielectric barrier discharge plasma treatment was applied to modify cellulose nanofibre (CNF) surfaces with and without ultrasonic irradiation. The plasma treatment improved the wetting by deionised water and glycerol, and increased the contents of oxygen, carbonyl group, and carboxyl group...... and amorphous phases. Ultrasonic irradiation also improved the uniformity of the treatment. Altogether, it is demonstrated that atmospheric pressure plasma treatment is a promising technique to modify the CNF surface before composite processing....

  11. Experimental and theoretical elucidation of structural and antioxidant properties of vanillylmandelic acid and its carboxylate anion

    Science.gov (United States)

    Dimić, Dušan; Milenković, Dejan; Ilić, Jelica; Šmit, Biljana; Amić, Ana; Marković, Zoran; Dimitrić Marković, Jasmina

    2018-06-01

    Vanillylmandelic acid (VMA), an important metabolite of catecholamines that is routinely screened as tumor marker, was investigated by the various spectroscopic techniques (IR, Raman, UV-Vis, antioxidant decolorization assay and NMR). Structures optimized by the employment of five common functionals (M05-2X, M06-2X, B3LYP, CAM-B3LYP, B3LYP-D3) were compared with the crystallographic data. The M05-2X functional reproduced the most reliable experimental bond lengths and angles (correlation coefficient >0.999). The importance of intramolecular hydrogen bonds for structural stability was discussed and quantified by the NBO analysis. The most prominent bands in vibrational spectrum were analyzed and compared to the experimental data. The positions of the carbon and hydrogen atoms in NMR spectra were well reproduced. The differences in UV-Vis spectrum were investigated by adding the explicit solvent and by performing NBO and QTAIM analyses. The discrepancy in the two spectra of about 50 nm could be explained by the solvent effect on carboxyl group. The most probable antioxidant activity mechanism was discussed for VMA and its carboxylate anion. The Molecular Docking study with the C - reactive protein additionally proved that variety of functional groups present in VMA and its anion allowed strong hydrogen and hydrophobic interactions.

  12. Electrochemical immobilization of biomolecules on gold surface modified with monolayered L-cysteine

    Energy Technology Data Exchange (ETDEWEB)

    Honda, Mitsunori, E-mail: honda.mitsunori@jaea.go.jp; Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Hirao, Norie

    2014-04-01

    Immobilization of organic molecules on the top of a metal surface is not easy because of lattice mismatch between organic and metal crystals. Gold atoms bind to thiol groups through strong chemical bonds, and a self-assembled monolayer of sulfur-terminated organic molecules is formed on the gold surface. Herein, we suggested that a monolayer of L-cysteine deposited on a gold surface can act as a buffer layer to immobilize biomolecules on the metal surface. We selected lactic acid as the immobilized biomolecule because it is one of the simplest carboxyl-containing biomolecules. The immobilization of lactic acid on the metal surface was carried out by an electrochemical method in an aqueous environment under the potential range varying from − 0.6 to + 0.8 V. The surface chemical states before and after the electrochemical reaction were characterized using X-ray photoelectron spectroscopy (XPS). The N 1s and C 1s XPS spectra showed that the L-cysteine-modified gold surface can immobilize lactic acid via peptide bonds. This technique might enable the immobilization of large organic molecules and biomolecules. - Highlights: • Monolayer l-cysteine deposited on Au surface as a buffer layer to immobilize biomolecules. • Lactic acid as the immobilized biomolecule as it is simple carboxyl-containing biomolecule. • X-ray photoelectron spectroscopy (XPS) of surface chemical states, before and after. • L-cysteine-modified Au surface can immobilize lactic acid via peptide bonds.

  13. Electrochemical immobilization of biomolecules on gold surface modified with monolayered L-cysteine

    International Nuclear Information System (INIS)

    Honda, Mitsunori; Baba, Yuji; Sekiguchi, Tetsuhiro; Shimoyama, Iwao; Hirao, Norie

    2014-01-01

    Immobilization of organic molecules on the top of a metal surface is not easy because of lattice mismatch between organic and metal crystals. Gold atoms bind to thiol groups through strong chemical bonds, and a self-assembled monolayer of sulfur-terminated organic molecules is formed on the gold surface. Herein, we suggested that a monolayer of L-cysteine deposited on a gold surface can act as a buffer layer to immobilize biomolecules on the metal surface. We selected lactic acid as the immobilized biomolecule because it is one of the simplest carboxyl-containing biomolecules. The immobilization of lactic acid on the metal surface was carried out by an electrochemical method in an aqueous environment under the potential range varying from − 0.6 to + 0.8 V. The surface chemical states before and after the electrochemical reaction were characterized using X-ray photoelectron spectroscopy (XPS). The N 1s and C 1s XPS spectra showed that the L-cysteine-modified gold surface can immobilize lactic acid via peptide bonds. This technique might enable the immobilization of large organic molecules and biomolecules. - Highlights: • Monolayer l-cysteine deposited on Au surface as a buffer layer to immobilize biomolecules. • Lactic acid as the immobilized biomolecule as it is simple carboxyl-containing biomolecule. • X-ray photoelectron spectroscopy (XPS) of surface chemical states, before and after. • L-cysteine-modified Au surface can immobilize lactic acid via peptide bonds

  14. Giant regular polyhedra from calixarene carboxylates and uranyl

    Science.gov (United States)

    Pasquale, Sara; Sattin, Sara; Escudero-Adán, Eduardo C.; Martínez-Belmonte, Marta; de Mendoza, Javier

    2012-01-01

    Self-assembly of large multi-component systems is a common strategy for the bottom-up construction of discrete, well-defined, nanoscopic-sized cages. Icosahedral or pseudospherical viral capsids, built up from hundreds of identical proteins, constitute typical examples of the complexity attained by biological self-assembly. Chemical versions of the so-called 5 Platonic regular or 13 Archimedean semi-regular polyhedra are usually assembled combining molecular platforms with metals with commensurate coordination spheres. Here we report novel, self-assembled cages, using the conical-shaped carboxylic acid derivatives of calix[4]arene and calix[5]arene as ligands, and the uranyl cation UO22+ as a metallic counterpart, which coordinates with three carboxylates at the equatorial plane, giving rise to hexagonal bipyramidal architectures. As a result, octahedral and icosahedral anionic metallocages of nanoscopic dimensions are formed with an unusually small number of components. PMID:22510690

  15. CARBOXYLIC ACIDS OF HERB OF THYMUS CRETACEUS KLOK. ET SCHOST

    Directory of Open Access Journals (Sweden)

    V. N. Bubenchikova

    2014-01-01

    Full Text Available We have studied carboxylic acids of the herb of Thymus cretaceus Klok. et Schost which is widespread on a territory of some regions (Belgorod, Voronezh. The study was carried out using gas-liquid chromatography at Agilent Technologies 6890 chromatographer with massspectrometric detector 5973 N. Acids concentration was calculated by means of inner standard.We have established that carboxylic acids of Thymus cretaceus are represented by 34 compounds. Palmitic (1779.02 mg/kg, behenic (1084.15 mg/kg, levulinic (986.24 mg/kg and linoleic acids (678.82 mg/kg predominate among fatty acids; citric (9835.14 mg/kg, malonic (447.91 mg/kg and oxalic acids (388.32 mg/kg predominate among organic acids; andferulic acid predominate amongphenolcarbonic acids.

  16. Variation in chemical, colloidal and electrochemical properties of carbon nanotubes with the degree of carboxylation

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Zheqiong; Wang, Zhiqian; Yu, Fang; Thakkar, Megha; Mitra, Somenath, E-mail: mitra@njit.edu [New Jersey Institute of Technology, Department of Chemistry and Environmental Science (United States)

    2017-01-15

    Multiwalled carbon nanotubes (CNTs) were carboxylated via microwave irradiation where the treatment time was varied to alter the degree of functionalization, and as many as one in 15 carbons in the CNT could be oxidized. Chemical, physical, electrochemical, and colloidal behavior of the carboxylated CNTs was studied. All properties changed with the degree of functionalization to a point beyond which they appeared to remain constant. The surface area increased from 173.9 to 270.9 m{sup 2}/g while the critical coagulation concentration (CCC) values increased from 142.14 to 168.69 mM in the presence of NaCl, and the corresponding increase was from 0.97 to 5.32 mM in the presence of MgCl{sub 2}. As seen from cyclic voltammetry curves, the functionalized CNTs showed mainly non-Faradic interactions with Na{sub 2}SO{sub 4,} but showed Faradic behaviors in alkaline KOH.

  17. Self-Standing Nanocellulose Janus-Type Films with Aldehyde and Carboxyl Functionalities.

    Science.gov (United States)

    Nypelö, Tiina; Amer, Hassan; Konnerth, Johannes; Potthast, Antje; Rosenau, Thomas

    2018-03-12

    Nanocellulose-based self-standing films are becoming a substrate for flexible electronics, diagnostics, and sensors. Strength and surface chemistry are vital variables for these film-based endeavors, the former is one of the assets of nanocellulose. To contribute to the latter, nanocellulose films are tuned with a side-specific functionalization, having an aldehyde and a carboxyl side. The functionalities were obtained combining premodification of the film components by periodate oxidation with ozone post-treatment. Periodate oxidation of cellulose nanocrystals results in film components that interact through intra- and intermolecular hemiacetals and lead to films with an elastic modulus of 11 GPa. The ozone treatment of one film side induces conversion of the aldehyde into carboxyl functionalities. The ozone treatment on individual crystals was largely destructive. Remarkably, such degradation is not observed for the self-standing film, and the film strength at break is preserved. Preserving a physically intact film despite ozone treatment is a credit to using the dry film structure held together by interparticle covalent linkages. Additionally, gas-phase post-treatment avoids disintegration that could result from immersion into solvents. The crystalline cellulose "Janus" film is suggested as an interfacial component in biomaterial engineering, separation technology, or in layered composite materials for tunable affinity between the layers.

  18. Identification of Key Residues for Enzymatic Carboxylate Reduction

    Directory of Open Access Journals (Sweden)

    Holly Stolterfoht

    2018-02-01

    Full Text Available Carboxylate reductases (CARs, E.C. 1.2.1.30 generate aldehydes from their corresponding carboxylic acid with high selectivity. Little is known about the structure of CARs and their catalytically important amino acid residues. The identification of key residues for carboxylate reduction provides a starting point to gain deeper understanding of enzymatic carboxylate reduction. A multiple sequence alignment of CARs with confirmed activity recently identified in our lab and from the literature revealed a fingerprint of conserved amino acids. We studied the function of conserved residues by multiple sequence alignments and mutational replacements of these residues. In this study, single-site alanine variants of Neurospora crassa CAR were investigated to determine the contribution of conserved residues to the function, expressability or stability of the enzyme. The effect of amino acid replacements was investigated by analyzing enzymatic activity of the variants in vivo and in vitro. Supported by molecular modeling, we interpreted that five of these residues are essential for catalytic activity, or substrate and co-substrate binding. We identified amino acid residues having significant impact on CAR activity. Replacement of His 237, Glu 433, Ser 595, Tyr 844, and Lys 848 by Ala abolish CAR activity, indicating their key role in acid reduction. These results may assist in the functional annotation of CAR coding genes in genomic databases. While some other conserved residues decreased activity or had no significant impact, four residues increased the specific activity of NcCAR variants when replaced by alanine. Finally, we showed that NcCAR wild-type and mutants efficiently reduce aliphatic acids.

  19. Surface Propensity of Atmospherically Relevant Amino Acids Studied by XPS.

    Science.gov (United States)

    Mocellin, Alexandra; Gomes, Anderson Herbert de Abreu; Araújo, Oscar Cardoso; de Brito, Arnaldo Naves; Björneholm, Olle

    2017-04-27

    Amino acids constitute an important fraction of the water-soluble organic nitrogen (WSON) compounds in aerosols and are involved in many processes in the atmosphere. In this work, we applied X-ray photoelectron spectroscopy (XPS) to study aqueous solutions of four amino acids, glycine, alanine, valine, and methionine, in their zwitterionic forms. We found that amino acids with hydrophilic side chains and smaller size, GLY and ALA, tend to stay in the bulk of the liquid, while the hydrophobic and bigger amino acids, VAL and MET, are found to concentrate more on the surface. We found experimental evidence that the amino acids have preferential orientation relative to the surface, with the hydrophobic side chain being closer to the surface than the hydrophilic carboxylate group. The observed amino acid surface propensity has implications in atmospheric science as the surface interactions play a central role in cloud droplet formation, and they should be considered in climate models.

  20. Transition metal-catalyzed carboxylation reactions with carbon dioxide.

    Science.gov (United States)

    Martin, Ruben; Tortajada, Andreu; Juliá-Hernández, Francisco; Borjesson, Marino; Moragas, Toni

    2018-05-03

    Driven by the inherent synthetic potential of CO2 as an abundant, inexpensive and renewable C1 chemical feedstock, the recent years have witnessed renewed interest in devising catalytic CO2 fixations into organic matter. Although the formation of C-C bonds via catalytic CO2 fixation remained rather limited for a long period of time, a close look into the recent literature data indicates that catalytic carboxylation reactions have entered a new era of exponential growth, evolving into a mature discipline that allows for streamlining the synthesis of carboxylic acids, building blocks of utmost relevance in industrial endeavours. These strategies have generally proven broadly applicability and convenient to perform. However, substantial challenges still need to be addressed reinforcing the need to cover metal-catalyzed carboxylation arena in a conceptual and concise manner, delineating the underlying new principles that are slowly emerging in this vibrant area of expertise. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Long-range interfacial electron transfer and electrocatalysis of molecular scale Prussian Blue nanoparticles linked to Au(111)-electrode surfaces by different chemical contacting groups

    DEFF Research Database (Denmark)

    Zhu, Nan; Ulstrup, Jens; Chi, Qijin

    2017-01-01

    We have explored interfacial electrochemical electron transfer (ET) and electrocatalysis of 5–6 nm Prussian Blue nanoparticles (PBNPs) immobilized on Au(111)-electrode surfaces via molecular wiring with variable-length, and differently functionalized thiol-based self-assembled molecular monolayers...... (SAMs). The SAMs contain positively (−NH3+) or negatively charged (–COO–) terminal group, as well an electrostatically neutral hydrophobic terminal group (–CH3). The surface microscopic structures of the immobilized PBNPs were characterized by high-resolution atomic force microscopy (AFM) directly...... in aqueous electrolyte solution under the same conditions as for electrochemical measurements. The PBNPs displayed fast and reversible interfacial ET on all the surfaces, notably in multi-ET steps as reflected in narrow voltammetric peaks. The ET kinetics can be controlled by adjusting the length of the SAM...

  2. Novel protocol for highly efficient gas-phase chemical derivatization of surface amine groups using trifluoroacetic anhydride

    Science.gov (United States)

    Duchoslav, Jiri; Kehrer, Matthias; Hinterreiter, Andreas; Duchoslav, Vojtech; Unterweger, Christoph; Fürst, Christian; Steinberger, Roland; Stifter, David

    2018-06-01

    In the current work, chemical derivatization of amine (NH2) groups with trifluoroacetic anhydride (TFAA) as an analytical method to improve the information scope of X-ray photoelectron spectroscopy (XPS) is investigated. TFAA is known to successfully label hydroxyl (OH) groups. With the introduction of a newly developed gas-phase derivatization protocol conducted at ambient pressure and using a catalyst also NH2 groups can now efficiently be labelled with a high yield and without the formation of unwanted by-products. By establishing a comprehensive and self-consistent database of reference binding energies for XPS a promising approach for distinguishing hydroxyl from amine groups is presented. The protocol was verified on different polymers, including poly(allylamine), poly(ethyleneimine), poly(vinylalcohol) and chitosan, the latter one containing both types of addressed chemical groups.

  3. Plasma surface modification of polypropylene track-etched membrane to improve its performance properties

    Science.gov (United States)

    Kravets, L. I.; Elinson, V. M.; Ibragimov, R. G.; Mitu, B.; Dinescu, G.

    2018-02-01

    The surface and electrochemical properties of polypropylene track-etched membrane treated by plasma of nitrogen, air and oxygen are studied. The effect of the plasma-forming gas composition on the surface morphology is considered. It has been found that the micro-relief of the membrane surface formed under the gas-discharge etching, changes. Moreover, the effect of the non-polymerizing gas plasma leads to formation of oxygen-containing functional groups, mostly carbonyl and carboxyl. It is shown that due to the formation of polar groups on the surface and its higher roughness, the wettability of the plasma-modified membranes improves. In addition, the presence of polar groups on the membrane surface layer modifies its electrochemical properties so that conductivity of plasma-treated membranes increase.

  4. Electroless oxidation of diamond surfaces in ceric and ferricyanide solutions: An easy way to produce 'C-O' functional groups

    Energy Technology Data Exchange (ETDEWEB)

    Simon, N., E-mail: nathalie.simon@uvsq.f [Institut Lavoisier de Versailles, UMR 8180, Universite de Versailles-St-Quentin en Yvelines, 45 avenue des Etats Unis, 78000 Versailles (France); Charrier, G.; Etcheberry, A. [Institut Lavoisier de Versailles, UMR 8180, Universite de Versailles-St-Quentin en Yvelines, 45 avenue des Etats Unis, 78000 Versailles (France)

    2010-08-01

    Despite many works are devoted to oxidation of diamond surfaces, it is still a challenge, to successfully produce well defined 'C-O' functions, particularly for functionalization purposes. In this paper we describe and compare, for the first time, the 'electroless' oxidation of as-deposited polycrystalline boron-doped diamond (BDD) films in ceric and ferricyanide solutions at room temperature. Both reactions efficiently generate oxygen functionalities on BDD surface. While a higher amount of 'C-O' moieties is produced with Ce{sup 4+} as oxidizing agent, the use of ferricyanide specie seems the most interesting to specifically generate hydroxyl groups. Additionally, this easy to perform oxidative method appears not damaging for diamond surfaces and adapted to conductive or non-conductive materials. The resulting surfaces were characterized using X-ray photoelectron spectroscopy, contact angle and capacitance-voltage analysis.

  5. On the lipid head group hydration of floating surface monolayers bound to self-assembled molecular protein layers

    DEFF Research Database (Denmark)

    Lösche, M.; Erdelen, C.; Rump, E.

    1994-01-01

    kept at low surface pressure before protein adsorption. The introduction of dipole moments at the interface by the admixture of phospholipids or the application of lateral pressure on the lipid monolayer before protein adsorption were found to impose an extension of the spacer moieties. The biotin...

  6. Influence of Group-III-metal and Ag adsorption on the Ge growth on Si(111) and its vicinal surface

    Energy Technology Data Exchange (ETDEWEB)

    Speckmann, Moritz

    2011-12-15

    In the framework of this thesis the surfactant-mediated heteroepitaxial growth of Ge on different Si surfaces has been investigated by means of low-energy electron microscopy, low-energy electron diffraction, spot-profile analysing low-energy electron diffraction, X-ray standing waves, grazing-incidence X-ray diffraction, x-ray photoemission electron microscopy, X-ray photoemission spectroscopy, scanning tunneling microscopy, scanning electron microscopy, transmission electron microscopy, and density functional theory calculations. As surfactants gallium, indium, and silver were used. The adsorption of Ga or In on the intrinsically faceted Si(112) surface leads to a smoothing of the surface and the formation of (N x 1) reconstructions, where a mixture of building blocks of different sizes is always present. For both adsorbates the overall periodicity on the surface is strongly dependent on the deposition temperature and the coverage. For the experimental conditions chosen here, the periodicities are in the range of 5.2{<=}N{<=}6.5 and 3.4{<=}N{<=}3.7 for Ga and In, respectively. The (N x 1) unit cells of Ga/Si(112) and In/Si(112) are found to consist of adsorbate atoms on terrace and step-edge sites, forming two atomic chains along the [110] direction. In the Ga-induced structures two Ga-vacancies per unit cell (one in the terrace and one in the step-edge site) are found and a continuous vacancy line on the surface is formed. In the In/Si(112) structure only one vacancy per unit cell in the step-edge site exists and, thus, a continuous adsorbate chain on the terrace sites is present. The adsorption of Ga or In on Si(112) strongly influences the subsequent Ge growth. Ge deposition on the Ga-terminated Si(112) surface leads to the formation of Ge nanowires, which are elongated along the Ga chains and reach lengths of up to 2000 nm for a growth temperature of 600 C. On In-covered Si(112), both small dash-like Ge islands and triangularly shaped islands are found, where

  7. Non-enzymatic palladium recovery on microbial and synthetic surfaces

    DEFF Research Database (Denmark)

    Rotaru, Amelia-Elena; Jiang, Wei; Finster, Kai

    2012-01-01

    in the presence of cells as compared to cell-free controls. We found no difference between native (untreated) and autoclaved cells, and could demonstrate that even a non-enzymatic protein (bovine serum albumin) stimulated Pd(II) reduction as efficiently as bacterial cells. Amine groups readily interact with Pd......(II), and to specifically test their role in surface-assisted Pd(II) reduction by formate, we replaced bacterial cells with polystyrene microparticles functionalized with amine or carboxyl groups. Amine-functionalized microparticles had the same effect on Pd(II) reduction as bacterial cells, and the effect could...... be hampered if the amine groups were blocked by acetylation. The interaction with amine groups was confirmed by infrared spectroscopy on whole cells and amine-functionalized microparticles. In conclusion, bio-supported Pd(II) reduction on microbial surfaces is possibly mediated by a non-enzymatic mechanism...

  8. Carboxyl-terminated butadiene-acrylonitrile-toughened epoxy/carboxyl-modified carbon nanotube nanocomposites: Thermal and mechanical properties

    Directory of Open Access Journals (Sweden)

    H. F. Xie

    2012-09-01

    Full Text Available Carboxyl-modified multi-walled carbon nanotubes (MWCNT–COOHs as nanofillers were incorporated into diglycidyl ether of bisphenol A (DGEBA toughened with carboxyl-terminated butadiene-acrylonitrile (CTBN. The carboxyl functional carbon nanotubes were characterized by Fourier-transform infrared spectroscopy and thermogravimetric analysis. Furthermore, cure kinetics, glass transition temperature (Tg, mechanical properties, thermal stability and morphology of DGEBA/CTBN/MWCNT–COOHs nanocomposites were investigated by differential scanning calorimetry (DSC, dynamic mechanical analysis (DMA, universal test machine, thermogravimetric analysis and scanning electron microscopy (SEM. DSC kinetic studies showed that the addition of MWCNT–COOHs accelerated the curing reaction of the rubber-toughened epoxy resin. DMA results revealed that Tg of rubber-toughened epoxy nanocomposites lowered with MWCNT–COOH contents. The tensile strength, elongation at break, flexural strength and flexural modulus of DGEBA/CTBN/MWCNT-COOHs nanocomposites were increased at lower MWCNT-COOH concentration. A homogenous dispersion of nanocomposites at lower MWCNT–COOH concentration was observed by SEM.

  9. Phosphazene-promoted metal-free ring-opening polymerization of ethylene oxide initiated by carboxylic acid

    KAUST Repository

    Zhao, Junpeng

    2014-03-11

    The effectiveness of carboxylic acid as initiator for the anionic ring-opening polymerization of ethylene oxide was investigated with a strong phosphazene base (t-BuP4) used as promoter. Kinetic study showed an induction period, i.e., transformation of carboxylic acid to hydroxyl ester, followed by slow chain growth together with simultaneous and fast end-group transesterification, which led to poly(ethylene oxide) (PEO) consisting of monoester (monohydroxyl), diester, and dihydroxyl species. An appropriate t-BuP4/acid ratio was proven to be essential to achieve better control over the polymerization and low dispersity of PEO. This work provides important information and enriches the toolbox for macromolecular and biomolecular engineering with protic initiating sites. © 2014 American Chemical Society.

  10. The effects of solvents and structure on the electronic absorption spectra of the isomeric pyridine carboxylic acid N-oxides

    Directory of Open Access Journals (Sweden)

    Drmanić Saša Ž.

    2013-01-01

    Full Text Available The ultraviolet absorption spectra of the carboxyl group of three isomeric pyridine carboxylic acids N-oxides (picolinic acid N-oxide, nicotinic acid N-oxide and isonicotinic acid N-oxide were determined in fourteen solvents in the wavelength range from 200 to 400 nm. The position of the absorption maxima (λmax of the examined acids showed that the ultraviolet absorption maximum wavelengths of picolinic acid N-oxide are the shortest, and those of isonicotinic acid N-oxide acid are the longest. In order to analyze the solvent effect on the obtained absorption spectra, the ultraviolet absorption frequencies of the electronic transitions in the carboxylic group of the examined acids were correlated using a total solvatochromic equation of the form max = v0 + sπ + aα+ bβ, where υmax is the absorption frequency (1/λmax, p is a measure of the solvent polarity, β represents the scale of solvent hydrogen bond acceptor basicities and α represent the scale of solvent hydrogen bond donor acidities. The correlation of the spectroscopic data was carried out by means of multiple linear regression analysis. The solvent effects on the ultraviolet absorption maximums of the examined acids were discussed.

  11. Ionic elastomers based on carboxylated nitrile rubber (XNBR and magnesium aluminum layered double hydroxide (hydrotalcite

    Directory of Open Access Journals (Sweden)

    A. Laskowska

    2014-06-01

    Full Text Available The presence of carboxyl groups in carboxylated nitrile butadiene rubber (XNBR allows it to be cured with different agents. This study considers the effect of crosslinking of XNBR by magnesium aluminum layered double hydroxide (MgAl-LDH, known also as hydrotalcite (HT, on rheometric, mechano-dynamical and barrier properties. Results of XNBR/HT composites containing various HT loadings without conventional curatives are compared with XNBR compound crosslinked with commonly used zinc oxide. Hydrotalcite acts as an effective crosslinking agent for XNBR, as is particularly evident from rheometric and Fourier transform infrared spectroscopy (FTIR studies. The existence of ionic crosslinks was also detected by dynamic mechanical analysis (DMA of the resulting composites. DMA studies revealed that the XNBR/HT composites exhibited two transitions – one occurring at low temperature is associated to the Tg of elastomer and the second at high temperature corresponds to the ionic transition temperature Ti. Simultaneous application of HT as a curing agent and a filler may deliver not only environmentally friendly, zinc oxide-free rubber product but also ionic elastomer composite with excellent mechanical, barrier and transparent properties.

  12. Coordination polymers: trapping of radionuclides and chemistry of tetravalent actinides (Th, U) carboxylates

    International Nuclear Information System (INIS)

    Falaise, Clement

    2014-01-01

    The use of nuclear energy obviously raises the question of the presence of radionuclides in the environment. Currently, their mitigation is a major issue associated with nuclear chemistry. This thesis focuses on both the trapping of radionuclides by porous solids called Metal-Organic Frameworks (MOF) and the crystal chemistry of the carboxylate of tetravalent actinides (AnIV). The academic knowledge of the reactivity of carboxylate of AnIV could help the understanding of actinides speciation in environment. We focused on the sequestration of iodine by aluminum based MOF. The functionalization (electron-donor group) of the MOF drastically enhances the iodine capture capacity. The removal of light actinides (Th and U) from aqueous solution was also investigated as well as the stability of (Al)-MOF under γ radiation. More than twenty coordination polymers based on tetravalent actinides have been synthesized and characterized by single crystal X-ray diffraction. The use of controlled hydrolysis promotes the formation of coordination polymers exhibiting polynuclear cluster ([U 4 ], [Th 6 ], [U 6 ] and [U 38 ]). In order to understand the formation of the largest cluster, the ex-situ study of the solvo-thermal synthesis of compound {U 38 } has also been investigated. (author)

  13. Tyrosine and carboxyl protonation changes in the bacteriorhodopsin photocycle. 2. Tyrosine-26 and -64

    International Nuclear Information System (INIS)

    Roepe, P.; Scherrer, P.; Ahl, P.L.; Gupta, S.K.D.; Bogomolni, R.A.; Herzfeld, J.; Rothschild, K.J.

    1987-01-01

    Low-temperature Fourier transform infrared (FTIR) and UV difference spectroscopies combined with selective tyrosine nitration and tyrosine isotopic labeling have been used to investigate the participation of tyrosines-26 and -64 in the bacteriorhodopsin (bR) photocycle. Nitration of Tyr-26 has no detectable effect on the FTIR or UV difference spectra of the BR 570 → K 630 or BR 570 → M 412 transitions. In contrast, nitration of Tyr-64 causes changes in both the FTIR and UV spectra of these transitions. However, this nitration does not alter tyrosine peaks in the FTIR difference spectra which have previously been associated with the protonation of a tyrosinate by K 630 and the deprotonation of a tyrosine by M 412 . Instead, Tyr-64 nitration appears to affect other tyrosine peaks. These results and changes in UV difference spectra upon Tyr-64 nitration are consistent with the deprotonation of Tyr-64 by M 412 as concluded previously. Effects on chromophore vibrations caused by Tyr-64 nitration are unaltered upon reducing the nitrotyrosine to aminotyrosine with sodium dithionite. Finally, nitro-Tyr-64 causes a shift in the frequency of a positive peak at 1739 cm -1 in the BR 570 → M 412 FTIR difference spectrum which reflects the protonation of a carboxyl-containing residue. The shift does not occur for samples containing amino-Tyr-64. These data suggest that Tyr-64 may interact with this carboxyl group

  14. Additional Nucleophile-Free FeCl3-Catalyzed Green Deprotection of 2,4-Dimethoxyphenylmethyl-Protected Alcohols and Carboxylic Acids.

    Science.gov (United States)

    Sawama, Yoshinari; Masuda, Masahiro; Honda, Akie; Yokoyama, Hiroki; Park, Kwihwan; Yasukawa, Naoki; Monguchi, Yasunari; Sajiki, Hironao

    2016-01-01

    The deprotection of the methoxyphenylmethyl (MPM) ether and ester derivatives can be generally achieved by the combinatorial use of a catalytic Lewis acid and stoichiometric nucleophile. The deprotections of 2,4-dimethoxyphenylmethyl (DMPM)-protected alcohols and carboxylic acids were found to be effectively catalyzed by iron(III) chloride without any additional nucleophile to form the deprotected mother alcohols and carboxylic acids in excellent yields. Since the present deprotection proceeds via the self-assembling mechanism of the 2,4-DMPM protective group itself to give the hardly-soluble resorcinarene derivative as a precipitate, the rigorous purification process by silica-gel column chromatography was unnecessary and the sufficiently-pure alcohols and carboxylic acids were easily obtained in satisfactory yields after simple filtration.

  15. Pd(II)/Bipyridine-Catalyzed Conjugate Addition of Arylboronic Acids to α,β-Unsaturated Carboxylic Acids. Synthesis of β-Quaternary Carbons Substituted Carboxylic Acids.

    Science.gov (United States)

    Liu, Rui; Yang, Zhenyu; Ni, Yuxin; Song, Kaixuan; Shen, Kai; Lin, Shaohui; Pan, Qinmin

    2017-08-04

    Pd(II)/bipyridine-catalyzed conjugate addition of arylboronic acids to α,β-unsaturated carboxylic acids (including β,β-disubstituted acrylic acids) was developed and optimized, which provided a mild and convenient method for the highly challenging synthesis of β-quaternary carbons substituted carboxylic acids.

  16. Structure and Dynamics of Hydroxyl-Functionalized Protic Ammonium Carboxylate Ionic Liquids.

    Science.gov (United States)

    Thummuru, Dhileep Nagi Reddy; Mallik, Bhabani S

    2017-10-26

    We performed classical molecular dynamics simulations to investigate the structure and dynamics of protic ionic liquids, 2-hydroxy ethylammonium acetate, ethylammonium hydroxyacetate, and 2-hydroxyethylammonium hydroxyacetate at ambient conditions. Structural properties such as density, radial distribution functions, spatial distribution functions, and structure factors have been calculated. Dynamic properties such as mean square displacements, as well as residence and hydrogen bond dynamics have also been calculated. Hydrogen bond lifetimes and residence times change with the addition of hydroxyl groups. We observe that when a hydroxyl group is present on the cation, dynamics become very slow and it forms a strong hydrogen bond with carboxylate oxygen atoms of the anion. The hydroxyl functionalized ILs show more dynamic diversity than structurally similar ILs.

  17. CARBOXYLATION OF SILVER NANOPARTICLES FOR THE IMMOBILIZATION OF β-GALACTOSIDASE AND ITS EFFICACY IN GALACTO-OLIGOSACCHARIDES PRODUCTION

    Directory of Open Access Journals (Sweden)

    Shakeel Ahmed Ansari

    2015-03-01

    Full Text Available The present study investigated the carboxylation of silver nanoparticles (AgNPs by 1:3 nitric acid-sulfuric acid mixtures for immobilizing Aspergillus oryzae β-galactosidase. Carboxylated AgNPs retained 93% enzyme upon immobilization and the enzyme did not leach out appreciably from the modified nanosupport in the presence of 100 mmol L-1 NaCl. Atomic force micrograph revealed the binding of β-galactosidase on the modified AgNPs. The optimal pH for soluble and carboxylated AgNPs adsorbed β-galactosidase (IβG was observed at pH 4.5 while the optimal operating temperature was broadened from 50 ºC to 60 ºC for IβG. Michaelis constant, Km was increased two and a half fold for IβG while Vmax decreases slightly as compared to soluble enzyme. β-galactosidase immobilized on surface functionalized AgNPs retained 70% biocatalytic activity even at 4% galactose concentration as compared to enzyme in solution. Our study showed that IβG produces greater amount of galacto-oligosaccharides at higher temperatures (50 ºC and 60 ºC from 0.1 mol L-1 lactose solution at pH 4.5 as compared to previous reports.

  18. Effects of Surface Charge and Functional Groups on the Adsorption and Binding Forms of Cu and Cd on Roots of indica and japonica Rice Cultivars

    Directory of Open Access Journals (Sweden)

    Zhao-Dong Liu

    2017-08-01

    Full Text Available This work was designed to understand the mechanisms of adsorption of copper (Cu and cadmium (Cd on roots of indica and japonica varieties of rice. Six varieties each of indica and japonica rice were grown in hydroponics and the chemical properties of the root surface were analyzed, including surface charges and functional groups (-COO- groups as measured by the streaming potential and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR. Binding forms of heavy metals adsorbed on rice roots were identified using sequential extraction methods. In rice roots exposed to Cu and Cd solutions, Cu existed mainly in both exchangeable and complexed forms, whereas Cd existed mainly in the exchangeable form. The amounts of exchangeable Cu and Cd and total adsorbed metal cations on the roots of indica varieties were significantly greater than those on the roots of japonica varieties, and the higher negative charges and the larger number of functional groups on the roots of indica varieties were responsible for their higher adsorption capacity and greater binding strength for Cu and Cd. Surface charge and functional groups on roots play an important role in the adsorption of Cu and Cd on the rice roots.

  19. Molecular modeling studies of interactions between sodium polyacrylate polymer and calcite surface

    Energy Technology Data Exchange (ETDEWEB)

    Ylikantola, A. [University of Jyväskylä, Department of Chemistry, P.O. Box 35, University of Jyväskylä, FI-40014 (Finland); Linnanto, J., E-mail: juha.m.linnanto@gmail.com [University of Jyväskylä, Department of Chemistry, P.O. Box 35, University of Jyväskylä, FI-40014 (Finland); University of Tartu, Institute of Physics, Riia 142, EE-51014 Tartu (Estonia); Knuutinen, J.; Oravilahti, A. [University of Jyväskylä, Department of Chemistry, P.O. Box 35, University of Jyväskylä, FI-40014 (Finland); Toivakka, M. [Åbo Akademi University, Laboratory of Paper Coating and Converting and Center for Functional Materials, FI-20500 Turku/Åbo (Finland)

    2013-07-01

    The interactions between calcite pigment and sodium polyacrylate dispersing agent, widely used in papermaking as paper coating components, were investigated using classical force field and quantum chemical approaches. The objective was to understand interactions between the calcite surface and sodium polyacrylate polymer at 300 K using molecular dynamics simulations. A quantum mechanical ab initio Hartree–Fock method was also used to obtain detailed information about the sodium polyacrylate polymer structure. The effect of water molecules (moisture) on the interactions was also examined. Calculations showed that molecular weight, branching and the orientation of sodium polyacrylate polymers influence the interactions between the calcite surface and the polymer. The force field applied, and also water molecules, were found to have an impact on all systems studied. Ab initio Hartree–Fock calculations indicated that there are two types of coordination between sodium atoms and carboxylate groups of the sodium polyacrylate polymer, inter- and intra-carboxylate group coordination. In addition, ab initio Hartree–Fock calculations of the structure of the sodium polyacrylate polymer produced important information regarding interactions between the polymers and carboxylated styrene-butadiene latex particles.

  20. Aminopropyltriethoxysilane-mediated surface functionalization of hydroxyapatite nanoparticles: synthesis, characterization, and in vitro toxicity assay

    Directory of Open Access Journals (Sweden)

    Wang S

    2011-12-01

    Full Text Available Shige Wang1, Shihui Wen2, Mingwu Shen2, Rui Guo2, Xueyan Cao2, Jianhua Wang3, Xiangyang Shi1,2,41State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, 2College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, 3Department of Biochemistry and Molecular Cell Biology, School of Medicine, Shanghai Jiao Tong University, Shanghai, People's Republic of China; 4Centro de Química da Madeira, Universidade da Madeira, Campus da Penteada, Funchal, PortugalBackground: We report on aminopropyltriethoxysilane (APTS-mediated surface modification of nanohydroxyapatite with different surface functional groups for potential biomedical applications. In this study, nanohydroxyapatite covalently linked with APTS (n-HA-APTS was reacted with acetic anhydride or succinic anhydride to produce neutralized (n-HA-APTS.Ac or negatively charged (n-HA-APTS.SAH nanohydroxyapatite, respectively. Nanohydroxyapatite formed with amine, acetyl, and carboxyl groups was extensively characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, 1H nuclear magnetic resonance spectroscopy, X-ray diffraction, inductively coupled plasma-atomic emission spectroscopy, and zeta potential measurements.Results: In vitro 3-(4,5-dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide colorimetric assay revealed that the slight toxicity of the amine-functionalized n-HA-APTS could be eliminated by post-functionalization of APTS amines to form acetyl and carboxyl groups. Blood compatibility assessment demonstrated that the negligible hemolytic activity of the pristine nanohydroxyapatite particles did not appreciably change after APTS-mediated surface functionalization.Conclusion: APTS-mediated functionalization of nanohydroxyapatite with different surface groups may be useful for further functionalization of nanohydroxyapatite with biologically active materials, thereby providing possibilities for a broad range of

  1. Design of co-crystals/salts of some Nitrogenous bases and some derivatives of thiophene carboxylic acids through a combination of hydrogen and halogen bonds.

    Science.gov (United States)

    Jennifer, Samson Jegan; Muthiah, Packianathan Thomas

    2014-01-01

    The utility of N-heterocyclic bases to obtain molecular complexes with carboxylic acids is well studied. Depending on the solid state interaction between the N-heterocyclic base and a carboxylic acid a variety of neutral or ionic synthons are observed. Meanwhile, pyridines and pyrimidines have been frequently chosen in the area of crystal engineering for their multipurpose functionality. HT (hetero trimers) and LHT (linear heterotetramers) are the well known synthons that are formed in the presence of pyrimidines and carboxylic acids. Fourteen crystals involving various substituted thiophene carboxylic acid derivatives and nitrogenous bases were prepared and characterized by using single crystal X-ray diffraction. The 14 crystals can further be divided into two groups [1a-7a], [8b-14b] based on the nature of the nitrogenous base. Carboxylic acid to pyridine proton transfer has occurred in 3 compounds of each group. In addition to the commonly occurring hydrogen bond based pyridine/carboxylic acid and pyrimidine/carboxylic acid synthons which is the reason for assembly of primary motifs, various other interactions like Cl…Cl, Cl…O, C-H…Cl, C-H…S add additional support in organizing these supermolecules into extended architectures. It is also interesting to note that in all the compounds π-π stacking occurs between the pyrimidine-pyrimidine or pyridine-pyridine or acid-acid moieties rather than acid-pyrimidine/pyridine. In all the compounds (1a-14b) either neutral O-H…Npyridyl/pyrimidine or charge-assisted Npyridinium-H…Ocarboxylate hydrogen bonds are present. The HT (hetero trimers) and LHT (linear heterotetramers) are dominant in the crystal structures of the adducts containing N-heterocyclic bases with two proton acceptors (1a-7a). Similar type supramolecular ladders are observed in 5TPC44BIPY (8b), TPC44BIPY (9b), TPC44TMBP (11b). Among the seven compounds [8b-14b] the extended ligands are linear in all except for the TMBP (10b, 11b, 12b). The

  2. Monolayer arrangement of fatty hydroxystearic acids on graphite: Influence of hydroxyl groups

    Energy Technology Data Exchange (ETDEWEB)

    Medina, S. [Laboratorio de Rayos-X, Centro de Investigación Tecnología e Innovación, de la Universidad de Sevilla (CITIUS), Universidad de Sevilla, Avenida Reina Mercedes, 4B. 41012, Sevilla (Spain); Benítez, J.J.; Castro, M.A. [Instituto de Ciencia de Materiales de Sevilla, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Avenida Américo Vespucio, 49. 41092, Sevilla (Spain); Cerrillos, C. [Servicio de Microscopía, Centro de Investigación Tecnología e Innovación, de la Universidad de Sevilla (CITIUS), Universidad de Sevilla, Avenida Reina Mercedes, 4B. 41012, Sevilla (Spain); Millán, C. [Instituto de Ciencia de Materiales de Sevilla, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Avenida Américo Vespucio, 49. 41092, Sevilla (Spain); Alba, M.D., E-mail: alba@icmse.csic.es [Instituto de Ciencia de Materiales de Sevilla, Consejo Superior de Investigaciones Científicas-Universidad de Sevilla, Avenida Américo Vespucio, 49. 41092, Sevilla (Spain)

    2013-07-31

    Previous studies have indicated that long-chain linear carboxylic acids form commensurate packed crystalline monolayers on graphite even at temperatures above their melting point. This study examines the effect on the monolayer formation and structure of adding one or more secondary hydroxyl, functional groups to the stearic acid skeleton (namely, 12-hydroxystearic and 9,10-dihydroxystearic acid). Moreover, a comparative study of the monolayer formation on recompressed and monocrystalline graphite has been performed through X-ray diffraction (XRD) and Scanning Tunneling Microscopy (STM), respectively. The Differential Scanning Calorimetry (DSC) and XRD data were used to confirm the formation of solid monolayers and XRD data have provided a detailed structural analysis of the monolayers in good correspondence with obtained STM images. DSC and XRD have demonstrated that, in stearic acid and 12-hydroxystearic acid adsorbed onto graphite, the monolayer melted at a higher temperature than the bulk form of the carboxylic acid. However, no difference was observed between the melting point of the monolayer and the bulk form for 9,10-dihydroxystearic acid adsorbed onto graphite. STM results indicated that all acids on the surface have a rectangular p2 monolayer structure, whose lattice parameters were uniaxially commensurate on the a-axis. This structure does not correlate with the initial structure of the pure compounds after dissolving, but it is conditioned to favor a) hydrogen bond formation between the carboxylic groups and b) formation of hydrogen bonds between secondary hydroxyl groups, if spatially permissible. Therefore, the presence of hydroxyl functional groups affects the secondary structure and behavior of stearic acid in the monolayer. - Highlights: • Hydroxyl functional groups affect structure and behavior of acids in the monolayer. • Acids on the surface have a rectangular p2 monolayer structure. • Lattice parameters of acids are uniaxially

  3. LANL Virtual Center for Chemical Hydrogen Storage: Chemical Hydrogen Storage Using Ultra-high Surface Area Main Group Materials

    Energy Technology Data Exchange (ETDEWEB)

    Susan M. Kauzlarich; Phillip P. Power; Doinita Neiner; Alex Pickering; Eric Rivard; Bobby Ellis, T. M.; Atkins, A. Merrill; R. Wolf; Julia Wang

    2010-09-05

    The focus of the project was to design and synthesize light element compounds and nanomaterials that will reversibly store molecular hydrogen for hydrogen storage materials. The primary targets investigated during the last year were amine and hydrogen terminated silicon (Si) nanoparticles, Si alloyed with lighter elements (carbon (C) and boron (B)) and boron nanoparticles. The large surface area of nanoparticles should facilitate a favorable weight to volume ratio, while the low molecular weight elements such as B, nitrogen (N), and Si exist in a variety of inexpensive and readily available precursors. Furthermore, small NPs of Si are nontoxic and non-corrosive. Insights gained from these studies will be applied toward the design and synthesis of hydrogen storage materials that meet the DOE 2010 hydrogen storage targets: cost, hydrogen capacity and reversibility. Two primary routes were explored for the production of nanoparticles smaller than 10 nm in diameter. The first was the reduction of the elemental halides to achieve nanomaterials with chloride surface termination that could subsequently be replaced with amine or hydrogen. The second was the reaction of alkali metal Si or Si alloys with ammonium halides to produce hydrogen capped nanomaterials. These materials were characterized via X-ray powder diffraction, TEM, FTIR, TG/DSC, and NMR spectroscopy.

  4. Carboxyl-terminal Truncations of ClC-Kb Abolish Channel Activation by Barttin Via Modified Common Gating and Trafficking.

    Science.gov (United States)

    Stölting, Gabriel; Bungert-Plümke, Stefanie; Franzen, Arne; Fahlke, Christoph

    2015-12-18

    ClC-K chloride channels are crucial for auditory transduction and urine concentration. Mutations in CLCNKB, the gene encoding the renal chloride channel hClC-Kb, cause Bartter syndrome type III, a human genetic condition characterized by polyuria, hypokalemia, and alkalosis. In recent years, several Bartter syndrome-associated mutations have been described that result in truncations of the intracellular carboxyl terminus of hClC-Kb. We here used a combination of whole-cell patch clamp, confocal imaging, co-immunoprecipitation, and surface biotinylation to study the functional consequences of a frequent CLCNKB mutation that creates a premature stop codon at Trp-610. We found that W610X leaves the association of hClC-Kb and the accessory subunit barttin unaffected, but impairs its regulation by barttin. W610X attenuates hClC-Kb surface membrane insertion. Moreover, W610X results in hClC-Kb channel opening in the absence of barttin and prevents further barttin-mediated activation. To describe how the carboxyl terminus modifies the regulation by barttin we used V166E rClC-K1. V166E rClC-K1 is active without barttin and exhibits prominent, barttin-regulated voltage-dependent gating. Electrophysiological characterization of truncated V166E rClC-K1 demonstrated that the distal carboxyl terminus is necessary for slow cooperative gating. Since barttin modifies this particular gating process, channels lacking the distal carboxyl-terminal domain are no longer regulated by the accessory subunit. Our results demonstrate that the carboxyl terminus of hClC-Kb is not part of the binding site for barttin, but functionally modifies the interplay with barttin. The loss-of-activation of truncated hClC-Kb channels in heterologous expression systems fully explains the reduced basolateral chloride conductance in affected kidneys and the clinical symptoms of Bartter syndrome patients. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  5. Atmospheric chemistry of carboxylic acids: microbial implication versus photochemistry

    Science.gov (United States)

    Vaïtilingom, M.; Charbouillot, T.; Deguillaume, L.; Maisonobe, R.; Parazols, M.; Amato, P.; Sancelme, M.; Delort, A.-M.

    2011-08-01

    The objective of this work was to compare experimentally the contribution of photochemistry vs. microbial activity to the degradation of carboxylic acids present in cloud water. For this, we selected 17 strains representative of the microflora existing in real clouds and worked on two distinct artificial cloud media that reproduce marine and continental cloud chemical composition. Photodegradation experiments with hydrogen peroxide (H2O2) as a source of hydroxyl radicals were performed under the same microcosm conditions using two irradiation systems. Biodegradation and photodegradation rates of acetate, formate, oxalate and succinate were measured on both media at 5 °C and 17 °C and were shown to be on the same order of magnitude (around 10-10-10-11 M s-1). The chemical composition (marine or continental origin) had little influence on photodegradation and biodegradation rates while the temperature shift from 17 °C to 5 °C decreased biodegradation rates of a factor 2 to 5. In order to test other photochemical scenarios, theoretical photodegradation rates were calculated considering hydroxyl (OH) radical concentration values in cloud water estimated by cloud chemistry modelling studies and available reaction rate constants of carboxylic compounds with both hydroxyl and nitrate radicals. Considering high OH concentration ([OH] = 1 × 10-12 M) led to no significant contribution of microbial activity in the destruction of carboxylic acids. On the contrary, for lower OH concentration (at noon, [OH] = 1 × 10-14 M), microorganisms could efficiently compete with photochemistry and in similar contributions than the ones estimated by our experimental approach. Combining these two approaches (experimental and theoretical), our results led to the following conclusions: oxalate was only photodegraded; the photodegradation of formate was usually more efficient than its biodegradation; the biodegradation of acetate and succinate seemed to exceed their photodegradation.

  6. Modeling Donnan Dialysis Separation for Carboxylic Anion Recovery

    DEFF Research Database (Denmark)

    Prado Rubio, Oscar Andres; Møllerhøj, Martin; Jørgensen, Sten Bay

    2010-01-01

    layers and membranes. Donnan equilibrium, flux continuity of the transported ions, the electroneutrality condition and Faraday's law are employed to describe the electrical potential and concentration discontinuities at the interfaces. The Nernst-Planck equation is used to model the ion transport though...... boundary layers and membranes. The model consists of a system of partial differential equations that are solved numerically. The aim of this paper is to corroborate this general model for several monoprotic carboxylic acids reported in the literature. The model reproduces satisfactorily experimental fluxes...

  7. Effect of organic bases on extraction of gadolinium carboxylates

    International Nuclear Information System (INIS)

    Sukhan, V.V.; Frankovskij, V.A.

    1982-01-01

    The effect of pyridine, 2-aminopyridine, benzylamine, antipyrine and o-phenanthroline on the extraction of capronates and bromocapronates of gadolinium with chloroform is studied. Out of the studied organic bases benzylamine produces the highest synergetic effect. In the absence of organic bases gadolinium carboxylates, solvated by three molecules of carbonic acids, are extracted into organic phase. A possihility of extractional separation of gadolinium from comparable amounts of iron with the mixture of 1 M solutions of caproic or bromocaproic acids with 1 M benzylamine from 0.1 M solution of tartaric acids is shown [ru

  8. Transition Metal Catalyzed Synthesis of Carboxylic Acids, Imines, and Biaryls

    DEFF Research Database (Denmark)

    Santilli, Carola; Madsen, Robert

    the carboxylate.  Manganese catalyzed radical Kumada-type reaction between aryl halidesand aryl Grignard reagents. The reaction between aryl halides and aryl Grignard reagents catalyzed by MnCl2 has been extended to several methyl-substituted aryl iodide reagents byperforming the reaction at 120 ˚C in a microwave...... oven (Scheme ii). A limitation of the heterocoupling process is the concomitant dehalogenation of the aryl halide and homocoupling of the Grignard reagent leading low to moderate yields of the desired heterocoupling product. The mechanism of the cross-coupling process was investigated by performing two...

  9. Separation and determination of some carboxylic acids by capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Sladkov, V.; Fourest, B

    2006-07-01

    Separation and determination of some organic acids, mono-carboxylic (formic and acetic), dicarboxylic (oxalic and tartaric), tricarboxylic (citric) acids and aromatic acids (phtalic, benzoic, mellitic and trimellitic), by capillary electrophoresis are reviewed. The method development parameters, such as separation and injection mode, are discussed. Special attention is paid to the comparison of different detection types (spectroscopic and electrochemical). The optimisation of the carrier electrolyte composition (choice of carrier electrolyte, effect of pH, ionic strength, electro-osmotic flow modifier) is treated. Different additives (alkali-earth and transition metal ions, cyclodextrins and alcohol), which are often used for improving organic acid separation, are also considered. (authors)

  10. Separation and determination of some carboxylic acids by capillary electrophoresis

    International Nuclear Information System (INIS)

    Sladkov, V.; Fourest, B.

    2006-01-01

    Separation and determination of some organic acids, mono-carboxylic (formic and acetic), dicarboxylic (oxalic and tartaric), tricarboxylic (citric) acids and aromatic acids (phtalic, benzoic, mellitic and trimellitic), by capillary electrophoresis are reviewed. The method development parameters, such as separation and injection mode, are discussed. Special attention is paid to the comparison of different detection types (spectroscopic and electrochemical). The optimisation of the carrier electrolyte composition (choice of carrier electrolyte, effect of pH, ionic strength, electro-osmotic flow modifier) is treated. Different additives (alkali-earth and transition metal ions, cyclodextrins and alcohol), which are often used for improving organic acid separation, are also considered. (authors)

  11. l-2-Nitrimino-1,3-diazepane-4-carboxylic acid

    Directory of Open Access Journals (Sweden)

    Harutyun A. Karapetyan

    2008-05-01

    Full Text Available The cyclic form of l-nitroarginine, C6H10N4O4, crystallizes with two independent molecules in the asymmetric unit. According to the geometrical parameters, similar in both molecules, the structure corresponds to that of l-2-nitrimino-1,3-diazepane-4-carboxylic acid; there are, however, conformational differences between the independent molecules, one of them being close to a twisted chair while the other might be described as a rather flattened boat. All six active H atoms in the two molecules are involved in hydrogen bonds, two of which are intramolecular and four intermolecular, forming an infinite chain of molecules along the b axis.

  12. Carboxylated fullerene at the oil/water interface

    OpenAIRE

    Li, R; Chai, Y; Jiang, Y; Ashby, PD; Toor, A; Russell, TP

    2017-01-01

    © 2017 American Chemical Society. The self-assembly of carboxylated fullerene with poly(styrene-b-2-vinylpyridine) (PS-b-P2VP) with different molecular weights, poly-2-vinylpyridine, and amine-terminated polystyrene, at the interface between toluene and water was investigated. For all values of the pH, the functionalized fullerene interacted with the polymers at the water/toluene interface, forming a nanoparticle network, reducing the interfacial tension. At pH values of 4.84 and 7.8, robust,...

  13. Osteoblast cell response to surface-modified carbon nanotubes

    International Nuclear Information System (INIS)

    Zhang Faming; Weidmann, Arne; Nebe, J. Barbara; Burkel, Eberhard

    2012-01-01

    In order to investigate the interaction of cells with modified multi-walled carbon nanotubes (MWCNTs) for their potential biomedical applications, the MWCNTs were chemically modified with carboxylic acid groups (–COOH), polyvinyl alcohol (PVA) polymer and biomimetic apatite on their surfaces. Additionally, human osteoblast MG-63 cells were cultured in the presence of the surface-modified MWCNTs. The metabolic activities of osteoblastic cells, cell proliferation properties, as well as cell morphology were studied. The surface modification of MWCNTs with biomimetic apatite exhibited a significant increase in the cell viability of osteoblasts, up to 67.23%. In the proliferation phases, there were many more cells in the biomimetic apatite-modified MWCNT samples than in the MWCNTs–COOH. There were no obvious changes in cell morphology in osteoblastic MG-63 cells cultured in the presence of these chemically-modified MWCNTs. The surface modification of MWCNTs with apatite achieves an effective enhancement of their biocompatibility.

  14. The effects of liquid-phase oxidation of multiwall carbon nanotubes on their surface characteristics

    Science.gov (United States)

    Burmistrov, I. N.; Muratov, D. S.; Ilinykh, I. A.; Kolesnikov, E. A.; Godymchuk, A. Yu; Kuznetsov, D. V.

    2016-01-01

    The development of new sorbents based on nanostructured carbon materials recently became a perspective field of research. Main topic of current study is to investigate the effect of different regimes of multiwall carbon nanotubes (MWCNT) surface modification process on their structural characteristics. MWCNT samples were treated with nitric acid at high temperature. Structural properties were studied using low temperature nitrogen adsorption and acid-base back titration methods. The study showed that diluted nitric acid does not affect MWCNT structure. Concentrated nitric acid treatment leads to formation of 2.8 carboxylic groups per 1 nm2 of the sample surface.

  15. Investigation on the adsorption characteristics of anserine on the surface of colloidal silver nanoparticles.

    Science.gov (United States)

    Thomas, S; Maiti, N; Mukherjee, T; Kapoor, S

    2013-08-01

    The surface-enhanced Raman scattering (SERS) studies of anserine (beta-alanyl-N-methylhistidine) was carried out on colloidal silver nanoparticles to understand its adsorption characteristics. The experimentally observed Raman bands were assigned based on the results of DFT calculations. The studies suggest that the interaction of anserine is primarily through the carboxylate group with the imidazole ring in an upright position with respect to the silver surface. Concentration dependent SERS studies suggest a change in orientation at sub-monolayer concentration. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Readiness Review Plan for the Interim Remedial Action on Surface Debris in Waste Area Grouping 11 at Oak Ridge National Laboratory, Oak Ridge, TN

    International Nuclear Information System (INIS)

    1993-10-01

    This Readiness Review Plan was prepared by the Waste Area Grouping (WAG) 11 Site Project Readiness Review Team as an overview of the Interim Remedial Action on Surface Debris in WAG 11 project at Oak Ridge National Laboratory, including major readiness milestones, criteria development methodology, and a list of events to occur as part of the review process for determining readiness for each project phase

  17. Synthesis and complexation properties towards uranyl cation of carboxylic acid derivatives of p-tert-butyl-calix[6]arene

    International Nuclear Information System (INIS)

    Souane, R.

    2005-03-01

    In the fuel reprocessing plants radioactive metals, and more particularly, uranium in UO 2 2+ form in the various installations, have many varied physico-chemical forms and there is a risk of exposure and internal contamination in the nuclear industry. It is necessary to exert a medical control to ensure the protection of the health of the workers. This medical control is done by dosing uranyl cation in the urine of the exposed people. This work forms part of this context. Indeed, we prepared a ligand able to complex the ion uranyl and which is also to be grafted on a solid support. In the family of calixarenes, the calix[6]arenes functionalized by three or four carboxylic functions were selected like chelating molecules of the ion uranyl. The properties of complexation of these calixarenes were studied by potentiometry in methanol, under these conditions balances of protonation and complexation were determined and the constant partners were obtained using the Hyperquad program. We synthesized tri-carboxylic calix[6]arenes comprising of the groupings nitro (NO 2 ) in para position of phenol in order to see the influence of a substitution in para position on the complexation. We also synthesized calix[6]arenes tetra-carboxylic in order to show the role of an additional carboxylic acid grouping. The potentiometric study determined thermodynamic parameters of protonation and complexation of carboxylic calix[6]arenes. The results of the complexation highlighted which complex UO 2 L corresponding to the ligand para-tert-butyl-calix[6]arene tetra-acid is more stable than that corresponding to the ligand mono-nitro calix[6]arene tri-acid (ΔlogΒ110 = 4.3), and than the effect of the groupings nitro in para position has low influence on the complexation of UO 2 2+ . This makes it possible to consider as possible the grafting of the calix[6]arenes which one knows the behaviour of trapping. To this end we synthesized the ligand 23. (author)

  18. Analysis of surface contributions to external doses in a radioactively contaminated urban environment designed by the EMRAS-2 Urban Areas Working Group

    International Nuclear Information System (INIS)

    Hwang, Won Tae; Jeong, Hae Sun; Jeong, Hyo Joon; Kim, Eun Han; Han, Moon Hee; Kim, In Gyu

    2013-01-01

    Highlights: ► External dose and contribution from radio-activated surface were evaluated for EMRAS-2 Urban Areas Working Group scenarios. ► The external doses showed a distinctive difference with the locations and precipitation. ► The contribution of contaminated surfaces for external dose depends on locations and precipitation. ► These results provide the essential information for decision-making support of countermeasures. - Abstract: The EMRAS-2 Urban Areas Working Group, which is supported by the IAEA, has designed a variety of accidental scenarios to test and improve the capabilities of the models used for an evaluation of radioactive contamination in an urban environment. A variety of models including a Korean model, METRO-K, are used for predictive results on the hypothetical scenarios. This paper describes the predictive results of METRO-K for the hypothetical scenarios designed in the Working Group. The external dose resulting from the air contamination of Co-60 was evaluated, and its contribution was analyzed with time as a function of the location of a receptor and precipitation conditions at the time of the contamination event. As a result, the external doses showed a distinctive difference with the locations to be evaluated and the precipitation conditions. Moreover, the contribution of contaminated surfaces for external doses was strongly dependent on the locations to be evaluated and the precipitation conditions. These results will provide essential information to assist the decision-making of appropriate countermeasures in an emergency situation of a radioactively contaminated urban environment

  19. Density functional theory prediction of pKa for carboxylated single-wall carbon nanotubes and graphene

    Science.gov (United States)

    Li, Hao; Fu, Aiping; Xue, Xuyan; Guo, Fengna; Huai, Wenbo; Chu, Tianshu; Wang, Zonghua

    2017-06-01

    Density functional calculations have been performed to investigate the acidities for the carboxylated single-wall carbon nanotubes and graphene. The pKa values for different COOH-functionalized models with varying lengths, diameters and chirality of nanotubes and with different edges of graphene were predicted using the SMD/M05-2X/6-31G* method combined with two universal thermodynamic cycles. The effects of following factors, such as, the functionalized position of carboxyl group, the Stone-Wales and single vacancy defects, on the acidity of the functionalized nanotube and graphene have also been evaluated. The deprotonated species have undergone decarboxylation when the hybridization mode of the carbon atom at the functionalization site changed from sp2 to sp3 both for the tube and graphene. The knowledge of the pKa values of the carboxylated nanotube and graphene could be of great help for the understanding of the nanocarbon materials in many diverse areas, including environmental protection, catalysis, electrochemistry and biochemistry.

  20. nPEG-TiO₂ nanoparticles: a facile route to elaborate nanostructured surfaces for biological applications.

    Science.gov (United States)

    Spadavecchia, J; Boujday, S; Landoulsi, J; Pradier, C-M

    2011-07-01

    We report the synthesis of diacid-terminated PEG-functionalized cubic TiO(2) nanocrystals by a simple one-step solvothermal method, and their further use to form nanostructured surfaces for protein immobilization. The relevance and major interest of the so-obtained nanocrystals are the presence of terminal carboxylic acid groups at their surface, as confirmed by infrared analyses, in addition to the surrounding PEG chains, essential to avoid non specific interactions. These functional chemical groups were used to (i) immobilize the synthesized nanocubes on a cysteamine-modified Au surface, and to (ii) attach proteins via a presumable covalent link. AFM images show that the shapes and the narrow size distribution of the nanocubes, observed by TEM, were preserved after their immobilization on the modified Au surface. Moreover, the efficiency and specificity of antigen recognition were demonstrated using spectroscopic analyses. Our successful approach provides a versatile and facile way to elaborate specific and sensitive nanostructured surfaces for biosensors.

  1. Formation and High-order Carboxylic Acids (RCOOH) in Interstellar Analogous Ices of Carbon Dioxide (CO2) and Methane(CH4)

    Science.gov (United States)

    Zhu, Cheng; Turner, Andrew M.; Abplanalp, Matthew J.; Kaiser, Ralf I.

    2018-01-01

    This laboratory study simulated the abiotic formation of carboxylic acids (RCOOH) in interstellar analogous ices of carbon dioxide (CO2) and methane (CH4) at 10 K upon exposure to energetic electrons. The chemical processing of the ices and the subsequent warm-up phase were monitored online and in situ, exploiting Fourier Transform Infrared Spectrometry and quadrupole mass spectrometry. Characteristic absorptions of functional groups of carboxylic acids (RCOOH) were observed in the infrared spectra of the irradiated ice. Two proposed reaction mechanisms replicated the kinetic profiles of the carboxylic acids along with the decay profile of the precursors during the irradiation via hydrocarbon formation, followed by carboxylation and/or through acetic acid along with mass growth processes of the alkyl chain. Mass spectra recorded during the warm-up phase demonstrated that these acids are distributed from acetic acid (CH3COOH) up to decanoic acid (C9H19COOH). High-dose irradiation studies (91 ± 14 eV) converted low-molecular-weight acids such as acetic acid (CH3COOH) and propionic acid (C2H5COOH) to higher-molecular-weight carboxylic acids, compared to low-dose irradiation studies (18 ± 3 eV). The traces of the {{{H}}}2{{C}}= {{C}}({OH}{)}2+ (m/z = 60) fragment—a link to linear carboxylic acids—implied that higher-order acids (C n H2n+1COOH, n ≥ 5) are likely branched, which correlates with the recent analysis of the structures of the monocarboxylic acids in the Murchison meteorite.