In-situ optical spectroscopy and electronic properties of pyrrole sub-monolayers on Ga-rich GaAs(001)

International Nuclear Information System (INIS)

Bruhn, Thomas; Ewald, Marcel; Fimland, Bjørn-Ove; Kneissl, Michael; Esser, Norbert; Vogt, Patrick

2011-01-01

We report on the characterization of sub-monolayers of pyrrole adsorbed on Ga-rich GaAs(001) surfaces. The interfaces were characterized by scanning tunneling microscopy (STM), scanning tunneling spectroscopy (STS) and reflectance anisotropy spectroscopy (RAS) in a spectral range between 1.5 and 8 eV. The adsorption of pyrrole on Ga-rich GaAs(001) modifies the RAS spectrum of the clean GaAs surface significantly at the surface transitions at 2.2 and 3.5 eV indicating a chemisorption of the molecules. By the help of transients at these surface transitions during the adsorption process, we were able to prepare different molecular coverages from a sub-monolayer up to a complete molecular layer. The different coverages of pyrrole were imaged by STM and electronically characterized by STS. The measurements reveal that the adsorbed molecules electronically insulate the surface and indicate the formation of new interface states around −3.5 and +4.2 eV. The RAS measurements in the UV region show new anisotropies in the spectral range of the optical transitions of the adsorbed pyrrole molecules. Our measurements demonstrate the potential of optical and electronic spectroscopy methods for the characterization of atomically thin molecular layers on semiconductor surfaces allowing a direct access to the properties of single adsorbed molecules.

Syntheses of Calix[4]Pyrroles by Amberlyst-15 Catalyzed Cyclocondensations of Pyrrole with Selected Ketones

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Tanuja Bisht

2007-11-01

Full Text Available A facile and efficient protocol is reported for the synthesis of calix[4]pyrrolesand N-confused calix[4]pyrroles in moderate to excellent yields by reaction of dialkyl orcycloalkyl ketones with pyrrole catalyzed by reusable AmberlystTM-15 under eco-friendlyconditions.

Pyrrole-Pyridine and Pyrrole-Naphthyridine Hosts for Anion Recognition

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M. Angeles García

2015-05-01

Full Text Available The association constants of the complexes formed by two hosts containing pyrrole, amide and azine (pyridine and 1,8-naphthyridine groups and six guests, all monoanions (Cl−, CH3CO2−, NO3−, H2PO4−, BF4−, PF6−, have been determined using NMR titrations. The X-ray crystal structure of the host N2,N5-bis(6-methylpyridin-2-yl-3,4-diphenyl-1H-pyrrole- 2,5-dicarboxamide (1 has been solved (P21/c monoclinic space group. B3LYP/6-31G(d,p and calculations were carried out in an attempt to rationalize the trends observed in the experimental association constants.

Pyrrole PMOs, incorporating new N-heterocyclic compounds on an ethene-PMO through Diels–Alder reactions

International Nuclear Information System (INIS)

Esquivel, Dolores; De Canck, Els; Jiménez-Sanchidrián, César; Romero-Salguero, Francisco J.; Van Der Voort, Pascal

2014-01-01

The ethenylene bridges on the walls of an ethenylene-bridged periodic mesoporous organosilica were successfully modified with a variety of pyrrole derivatives – pyrrole, methylpyrrole, dimethylpyrrole, trimethylpyrrole and 1-phenylpyrrole – through Diels–Alder reactions. X-ray diffraction measurements and N 2 adsorption–desorption analysis confirmed the preservation of the ordering and mesoporosity of the parent material as well as the decoration of the pores with the surface Diels–Alder adducts. Moreover, other techniques such as DRIFT, 13 C and 29 Si nuclear magnetic resonances revealed the formation of the surface N-heterocyclic compounds at the parent ethenylene sites. - Highlights: • Chemical modification of the double bonds on an ethene-PMO through the Diels–Alder reaction. • A family of pyrrole derivatives act as dienes in the Diels–Alder reaction. • Well-ordering and mesoporosity are retained after the post-functionalization. • N-containing compounds on the surface of ethene-PMO are present after the Diels–Alder reaction

Pyrrole PMOs, incorporating new N-heterocyclic compounds on an ethene-PMO through Diels–Alder reactions

Energy Technology Data Exchange (ETDEWEB)

Esquivel, Dolores; De Canck, Els [Center for Ordered Materials, Organometallics and Catalysis, Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent (Belgium); Jiménez-Sanchidrián, César [Department of Organic Chemistry, Nanochemistry and Fine Chemistry Research Institute (IUIQFN), Faculty of Sciences, University of Córdoba, Campus de Rabanales, Marie Curie Building, Ctra. Nnal. IV, km 396, 14071 Córdoba (Spain); Romero-Salguero, Francisco J., E-mail: qo2rosaf@uco.es [Department of Organic Chemistry, Nanochemistry and Fine Chemistry Research Institute (IUIQFN), Faculty of Sciences, University of Córdoba, Campus de Rabanales, Marie Curie Building, Ctra. Nnal. IV, km 396, 14071 Córdoba (Spain); Van Der Voort, Pascal, E-mail: pascal.vandervoort@ugent.be [Center for Ordered Materials, Organometallics and Catalysis, Department of Inorganic and Physical Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent (Belgium)

2014-11-14

The ethenylene bridges on the walls of an ethenylene-bridged periodic mesoporous organosilica were successfully modified with a variety of pyrrole derivatives – pyrrole, methylpyrrole, dimethylpyrrole, trimethylpyrrole and 1-phenylpyrrole – through Diels–Alder reactions. X-ray diffraction measurements and N{sub 2} adsorption–desorption analysis confirmed the preservation of the ordering and mesoporosity of the parent material as well as the decoration of the pores with the surface Diels–Alder adducts. Moreover, other techniques such as DRIFT, {sup 13}C and {sup 29}Si nuclear magnetic resonances revealed the formation of the surface N-heterocyclic compounds at the parent ethenylene sites. - Highlights: • Chemical modification of the double bonds on an ethene-PMO through the Diels–Alder reaction. • A family of pyrrole derivatives act as dienes in the Diels–Alder reaction. • Well-ordering and mesoporosity are retained after the post-functionalization. • N-containing compounds on the surface of ethene-PMO are present after the Diels–Alder reaction.

pyrroles

Indian Academy of Sciences (India)

and various aldehydes to afford 4H-pyrano[3,2-b]pyrrole derivatives in moderate to good yield using ferric .... (pyran C5), 122.8, 122.4, 128.9, 132.7, 133.0, 141.6. (Ar-C), 179.0 (pyran C2). 2.2f ..... After Michael-type addition of malononitrile.

Antitumor Activity of a 5-Hydroxy-1H-Pyrrol-2-(5H-One-Based Synthetic Small Molecule In Vitro and In Vivo.

Directory of Open Access Journals (Sweden)

Yunyun Geng

Full Text Available Alternative chemo-reagents are in great demand because chemotherapy resistance is one of the major challenges in current cancer treatment. 5-hydoxy-1H-pyrrol-2-(5H-one is an important N-heterocyclic scaffold that is present in natural products and medicinal chemistry. However, its antitumor activity has not been systematically explored. In this study, we screened a panel of 5-hydoxy-1H-pyrrol-2-(5H-one derivatives and identified compound 1d as possessing strong anti-proliferative activity in multiple cancer cell lines. Cell cycle analysis revealed that 1d can induce S-phase cell cycle arrest and that HCT116 was sensitive to 1d-induced apoptosis. Further analysis indicated that 1d preferentially induced DNA damage and p53 activation in HCT116 cells and that 1d-induced apoptosis is partly dependent on p53. Furthermore, we showed that 1d significantly suppressed tumor growth in xenograft tumor models in vivo. Taken together, our results suggest that 5-hydoxy-1H-pyrrol-2-(5H-one derivatives bear potential antitumor activity and that 1d is an effective agent for cancer treatment.

Heterogeneous hydrogenation using stable and reusable calix[4]pyrrole fenced Pt nanoparticles and its mechanistic insight

Science.gov (United States)

Kongor, Anita; Panchal, Manthan; Athar, Mohd; Mehta, Viren; Bhatt, Keyur; Jha, P. C.; Jain, Vinod

2018-04-01

Novel calix[4]pyrrole encapsulated platinum nanoparticles (PtNPs) have been prepared in the aqueous medium using meso-tetra(methoxy) meso-tetra (4-phenoxy acetohydrazide) calix[4]pyrrole (MCPTH) as both reducing as well as the capping agent. The developed MCPTH-PtNPs nano-assembly has been characterized by HRTEM, XRD, XPS, TGA and FTIR methods. Grafting capability of MCPTH on PtNPs was envisaged by molecular dynamics simulations that renders towards the complemented role of ligand in capping the surface via metal-acceptor interactions. These nanoparticles have been exploited for chemoselective hydrogenation of nitroarenes using molecular hydrogen at room temperature. Supplemented computational and experimental apprehension clearly corroborates that hydrazide group remains in close contact with the surface and provides adequate coordination sites for the adsorption of nitrenes; required for hydrogenation. This catalytic approach can be conceived as an important tool for determining the electronic and structural influence on the catalytic activity which may open new vistas pertaining to the use of calix functionalized nanocatalyst.

Pyrrolic-N-doped graphene oxide/Fe2O3 mesocrystal nanocomposite: Efficient charge transfer and enhanced photo-Fenton catalytic activity

Science.gov (United States)

Liu, Bing; Tian, Lihong; Wang, Ran; Yang, Jinfeng; Guan, Rong; Chen, Xiaobo

2017-11-01

Though α-Fe2O3 has attracted much attention in photocatalytic or Fenton-catalytic degradation of organic contaminants, its performance is still unsatisfactory due to fast recombination of electrons and holes in photocatalytic process and the difficult conversion of Fe(II) and Fe(III) in Fenton reaction. Herein, a pyrrolic N-doped graphene oxide/Fe2O3 mesocrystal (NG-Fe2O3) nanocomposite with good distribution is synthesized by a simple solvothermal method and adjusting the oxygen-containing groups on graphene oxide. The morphology of NG-Fe2O3 contributes to a relatively large BET surface area and an intimate contact between NG and Fe2O3. These two important factors along with the excellent electro-conductivity of pyrrolic-N doped GO result in the efficient separation of electron-hole pairs and fast conversion of Fe(II)and Fe(III) in photo-Fenton synergistic reaction. Thus, a remarkably improved photo-Fenton catalytic activity of NG-Fe2O3 is obtained. The degrading rate on methyl blue increases by 1.5 times and the conversion rate of glyphosate increases by 2.3 times under visible light irradiation, compared to pristine α-Fe2O3 mesocrystals.

Zinc hexacyanoferrate film as an effective protecting layer in two-step and one-step electropolymerization of pyrrole on zinc substrate

Energy Technology Data Exchange (ETDEWEB)

Pournaghi-Azar, M.H. [Electroanalytical Chemistry Laboratory, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of)]. E-mail: pournaghiazar@tabrizu.ac.ir; Nahalparvari, H. [Electroanalytical Chemistry Laboratory, Faculty of Chemistry, University of Tabriz, Tabriz (Iran, Islamic Republic of)

2005-03-15

The two-step and one-step electrosynthesis processes of polypyrrole (PPy) films on the zinc substrate are described. The two-step process includes (i) the zinc surface pretreatment with hexacyanoferrate ion in the aqueous medium in order to form a zinc hexacyanoferrate (ZnHCF) film non-blocking passive layer on the surface and with the view to prevent its reactivity and (ii) electropolymerization of pyrrole on the ZnHCF vertical bar Zn-modified electrode in aqueous pyrrole solution. In this context, both the non-electrolytic and electrolytic procedures were adapted, and the effect of some experimental conditions such as supporting electrolyte, pH and temperature of the solution at the zinc surface pretreatment step as well as pyrrole concentration and electrochemical techniques at the polymerization step was investigated. By optimizing the experimental conditions in both steps, we have obtained a homogeneous and strongly adherent PPy films on the zinc substrate. The one-step process is based on the use of an aqueous medium containing Fe(CN){sub 6}{sup 4-} and pyrrole. The ferrocyanide ion passivates the substrate by formation of ZnHCF film during the electropolymerization process of pyrrole and therefore makes it possible to obtain strongly adherent PPy films, with controlled thickness, either by cyclic voltammetry or by electrolysis at constant current or constant potential without any previously treatment of the zinc electrode surface. The polypyrrole films deposited on the zinc electrode were characterized by cyclic voltammetry and scanning electron microscopic (SEM) measurement.

Zinc hexacyanoferrate film as an effective protecting layer in two-step and one-step electropolymerization of pyrrole on zinc substrate

International Nuclear Information System (INIS)

Pournaghi-Azar, M.H.; Nahalparvari, H.

2005-01-01

The two-step and one-step electrosynthesis processes of polypyrrole (PPy) films on the zinc substrate are described. The two-step process includes (i) the zinc surface pretreatment with hexacyanoferrate ion in the aqueous medium in order to form a zinc hexacyanoferrate (ZnHCF) film non-blocking passive layer on the surface and with the view to prevent its reactivity and (ii) electropolymerization of pyrrole on the ZnHCF vertical bar Zn-modified electrode in aqueous pyrrole solution. In this context, both the non-electrolytic and electrolytic procedures were adapted, and the effect of some experimental conditions such as supporting electrolyte, pH and temperature of the solution at the zinc surface pretreatment step as well as pyrrole concentration and electrochemical techniques at the polymerization step was investigated. By optimizing the experimental conditions in both steps, we have obtained a homogeneous and strongly adherent PPy films on the zinc substrate. The one-step process is based on the use of an aqueous medium containing Fe(CN) 6 4- and pyrrole. The ferrocyanide ion passivates the substrate by formation of ZnHCF film during the electropolymerization process of pyrrole and therefore makes it possible to obtain strongly adherent PPy films, with controlled thickness, either by cyclic voltammetry or by electrolysis at constant current or constant potential without any previously treatment of the zinc electrode surface. The polypyrrole films deposited on the zinc electrode were characterized by cyclic voltammetry and scanning electron microscopic (SEM) measurement

The nonadiabatic deactivation paths of pyrrole

International Nuclear Information System (INIS)

Barbatti, Mario; Vazdar, Mario; Aquino, Adelia J. A.; Eckert-Maksic, Mirjana; Lischka, Hans

2006-01-01

Multireference configuration interaction (MRCI) calculations have been performed for pyrrole with the aim of providing an explanation for the experimentally observed photochemical deactivation processes. Potential energy curves and minima on the crossing seam were determined using the analytic MRCI gradient and nonadiabatic coupling features of the COLUMBUS program system. A new deactivation mechanism based on an out-of-plane ring deformation is presented. This mechanism directly couples the charge transfer 1 ππ* and ground states. It may be responsible for more than 50% of the observed photofragments of ππ*-excited pyrrole. The ring deformation mechanism should act complementary to the previously proposed NH-stretching mechanism, thus offering a more complete interpretation of the pyrrole photodynamics

Influence of gamma irradiation on polymerization of pyrrole and glucose oxidase immobilization onto poly (pyrrole)/poly (vinyl alcohol) matrix

Energy Technology Data Exchange (ETDEWEB)

Idris, Sarada, E-mail: sarada@nuclearmalaysia.gov.my [Department of Radiation Technology, Malaysian Nuclear Agency, 43000, Bangi, Selangor (Malaysia); Department of Electrical, Electronic and Systems Engineering, Faculty of Engineering & Built Environment, Universiti Kebangsaan Malaysia, Bangi, 43600 (Malaysia); Bakar, Ahmad Ashrif A., E-mail: ashrif@ukm.edu.my [Department of Electrical, Electronic and Systems Engineering, Faculty of Engineering & Built Environment, Universiti Kebangsaan Malaysia, Bangi, 43600 (Malaysia); Thevy Ratnam, Chantara [Department of Radiation Technology, Malaysian Nuclear Agency, 43000, Bangi, Selangor (Malaysia); Kamaruddin, Nur Hasiba [Department of Electrical, Electronic and Systems Engineering, Faculty of Engineering & Built Environment, Universiti Kebangsaan Malaysia, Bangi, 43600 (Malaysia); Shaari, Sahbudin [Institute of Microengineering and Nanoelectronics, Universiti Kebangsaan Malaysia, Bangi, 43600 (Malaysia)

2017-04-01

Graphical abstract: The illustration of pyrrole polymerization, PVA crosslinking and immobilization of GOx onto polymer matrix. - Highlights: • Immobilization of glucose oxidase onto polymer matrices by gamma irradiation is proposed. • Crosslinking and grafting of polymers implies the immobilization reaction. • The mechanisms relies on gamma irradiation doses. • A simple single step process of polymerization, cross linking and immobilization by mean of gamma irradiation as was shown in Graphical abstract. - Abstract: This paper describes the immobilization of glucose oxidase, GOx onto polymer matrix comprising of poly(pyrrole), PPy and poly(vinyl alcohol), PVA using gamma irradiation technique. Py/PVA-GOx film was prepared by spreading PVA:GOx, 1:1 solution onto dried pyrrole film and exposed to gamma irradiation from cobalt 60 source at doses ranging from 0 to 60 kGy. The films were subjected to structural and morphological analyses by using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM), Field emission scanning electron microscope (FESEM) and Atomic-force microscopy (AFM) techniques. Similar studies were also made on pristine pyrrole film which served as control. The SEM and FTIR spectra of Py/PVA-GOx film revealed that pyrrole has been successfully polymerized through irradiation-induced reactions. The results on the morphological properties of the samples characterize using FESEM, SEM and AFM further confirmed the occurrence of radiation-induced modification of Py/PVA-GOx film. The FTIR spectra showed the existence of intermolecular interaction between polymer matrix and GOx indicating that GOx had been successfully immobilized onto Ppy/PVA matrix by radiation-induced reactions. Results revealed that radiation induced reactions such as polymerization of pyrrole, crosslinking of PVA, grafting between the adjacent PVA and pyrrole molecules as well as immobilization of GOx onto Ppy

Influence of gamma irradiation on polymerization of pyrrole and glucose oxidase immobilization onto poly (pyrrole)/poly (vinyl alcohol) matrix

International Nuclear Information System (INIS)

Idris, Sarada; Bakar, Ahmad Ashrif A.; Thevy Ratnam, Chantara; Kamaruddin, Nur Hasiba; Shaari, Sahbudin

2017-01-01

Graphical abstract: The illustration of pyrrole polymerization, PVA crosslinking and immobilization of GOx onto polymer matrix. - Highlights: • Immobilization of glucose oxidase onto polymer matrices by gamma irradiation is proposed. • Crosslinking and grafting of polymers implies the immobilization reaction. • The mechanisms relies on gamma irradiation doses. • A simple single step process of polymerization, cross linking and immobilization by mean of gamma irradiation as was shown in Graphical abstract. - Abstract: This paper describes the immobilization of glucose oxidase, GOx onto polymer matrix comprising of poly(pyrrole), PPy and poly(vinyl alcohol), PVA using gamma irradiation technique. Py/PVA-GOx film was prepared by spreading PVA:GOx, 1:1 solution onto dried pyrrole film and exposed to gamma irradiation from cobalt 60 source at doses ranging from 0 to 60 kGy. The films were subjected to structural and morphological analyses by using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM), Field emission scanning electron microscope (FESEM) and Atomic-force microscopy (AFM) techniques. Similar studies were also made on pristine pyrrole film which served as control. The SEM and FTIR spectra of Py/PVA-GOx film revealed that pyrrole has been successfully polymerized through irradiation-induced reactions. The results on the morphological properties of the samples characterize using FESEM, SEM and AFM further confirmed the occurrence of radiation-induced modification of Py/PVA-GOx film. The FTIR spectra showed the existence of intermolecular interaction between polymer matrix and GOx indicating that GOx had been successfully immobilized onto Ppy/PVA matrix by radiation-induced reactions. Results revealed that radiation induced reactions such as polymerization of pyrrole, crosslinking of PVA, grafting between the adjacent PVA and pyrrole molecules as well as immobilization of GOx onto Ppy

Poly (pyrrole-co-aniline) hollow nanosphere supported Pd nanoflowers as high-performance catalyst for methanol electrooxidation in alkaline media

International Nuclear Information System (INIS)

Fard, Leyla Abolghasemi; Ojani, Reza; Raoof, Jahan Bakhsh; Zare, Ehsan Nazarzadeh; Lakouraj, Moslem Mansour

2017-01-01

In this work, first poly (pyrrole-co-aniline) (PPCA) hollow nanosphere (HN) as a catalyst support material is fabricated through in-situ emulsion polymerization. Then we reported a one-step and template-free approach to fabricate Pd NFs on a PPCA HN coated glassy carbon electrode by a facile electrochemical approach. Several techniques such as FTIR (Fourier transform infrared spectroscopy), SEM (scanning electron microscopy) and EDS (energy dispersive spectroscopy) were utilized for the characterization of the synthesized materials. The catalytic performance of Pd NFs/PPCA HN catalyst is evaluated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy toward methanol oxidation as a model reaction in alkaline media. The comparison of specific activities for Pd NFs/PPCA HN (1.79 mA cm"−"2), Pd NFs/PPy (1.28 mA cm"−"2), Pd NFs/PANI (0.93 mA cm"−"2) and Pd NFs (0.78 mA cm"−"2) shows that the PPCA supported Pd NFs with high surface area exhibits the excellent electrocatalytic activity than other electrodes for the electro-oxidation reaction in alkaline media. This might be due to the easier charge transfer at conductive copolymer interfaces, higher electrochemically accessible surface areas and electronic conductivity. This strategy provides a promising platform for direct methanol fuel cells. - Highlights: • Pd nanoflowers supported on poly (pyrrole-co-aniline) hollow nanosphere is prepared by a facile electrochemical approach. • The as-prepared nanocatalyst displays the enhanced electrocatalytic activity and stability for methanol oxidation. • The high performance is attributed to facile electron transfer on poly (pyrrole-co-aniline) hollow nanosphere substrate.

New 1H-pyrrole-2,5-dione derivatives as efficient organic inhibitors of carbon steel corrosion in hydrochloric acid medium: Electrochemical, XPS and DFT studies

International Nuclear Information System (INIS)

Zarrouk, A.; Hammouti, B.; Lakhlifi, T.; Traisnel, M.; Vezin, H.; Bentiss, F.

2015-01-01

Highlights: • 1H-pyrrole derivatives act as good corrosion inhibitors for carbon steel in 1 M HCl. • Adsorption of the inhibitors on carbon steel surface obeys Langmuir’s isotherm. • XPS showed that the inhibitors are chemisorbed on the metal surface. • Quantum chemical parameters were correlated with experimental results. - Abstract: New 1H-pyrrole-2,5-dione derivatives, namely 1-phenyl-1H-pyrrole-2,5-dione (PPD) and 1-(4-methylphenyl)-1H-pyrrole-2,5-dione (MPPD) were synthesised and their inhibitive action against the corrosion of carbon steel in 1 M HCl solution were investigated at 308 K by weight loss, potentiodynamic polarization curves, and electrochemical impedance spectroscopy (EIS) methods. The results showed that the investigated 1H-pyrrole-2,5-dione derivatives are good corrosion inhibitors for carbon steel in 1 M HCl medium, their inhibition efficiency increased with inhibitor concentration, and MPPD is slightly more effective than PPD. Potentiostatic polarization study showed that PPD and MPPD are mixed-type inhibitors in 1 M HCl. Impedance experimental data revealed a frequency distribution of the capacitance, simulated as constant phase element. The results obtained from electrochemical and weight loss studies were in reasonable agreement. The adsorption of MPPD and PPD on steel surface obeyed Langmuir’s adsorption isotherm. Thermodynamic data and XPS analysis clearly indicated that the adsorption mechanism of 1H-pyrrole-2,5-dione derivatives on carbon steel surface in 1 M HCl solution is mainly controlled by a chemisorption process. Quantum chemical calculations using the Density Functional Theory (DFT) were performed on 1H-pyrrole-2,5-dione derivatives to determine the relationship between molecular structures and their inhibition efficiencies

Influence of gamma irradiation on polymerization of pyrrole and glucose oxidase immobilization onto poly (pyrrole)/poly (vinyl alcohol) matrix

Science.gov (United States)

Idris, Sarada; A. Bakar, Ahmad Ashrif; Thevy Ratnam, Chantara; Kamaruddin, Nur Hasiba; Shaari, Sahbudin

2017-04-01

This paper describes the immobilization of glucose oxidase, GOx onto polymer matrix comprising of poly(pyrrole), PPy and poly(vinyl alcohol), PVA using gamma irradiation technique. Py/PVA-GOx film was prepared by spreading PVA:GOx, 1:1 solution onto dried pyrrole film and exposed to gamma irradiation from cobalt 60 source at doses ranging from 0 to 60 kGy. The films were subjected to structural and morphological analyses by using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Scanning electron microscope (SEM), Field emission scanning electron microscope (FESEM) and Atomic-force microscopy (AFM) techniques. Similar studies were also made on pristine pyrrole film which served as control. The SEM and FTIR spectra of Py/PVA-GOx film revealed that pyrrole has been successfully polymerized through irradiation-induced reactions. The results on the morphological properties of the samples characterize using FESEM, SEM and AFM further confirmed the occurrence of radiation-induced modification of Py/PVA-GOx film. The FTIR spectra showed the existence of intermolecular interaction between polymer matrix and GOx indicating that GOx had been successfully immobilized onto Ppy/PVA matrix by radiation-induced reactions. Results revealed that radiation induced reactions such as polymerization of pyrrole, crosslinking of PVA, grafting between the adjacent PVA and pyrrole molecules as well as immobilization of GOx onto Ppy/PVA matrix occurred simultaneously upon gamma irradiation. The optimum dose for GOx immobilization in the polymer matrix found to be 40 kGy. Therefore it is clear that this irradiation technique offered a simple single process to produce Py/PVA-GOx film without additional crosslinking and polymerization agents.

Hydrolytic study of the copolymer Poly pyrrole/ Polyethyleneglycol and Poly pyrrole synthesized by plasma; Estudio hidrolitico del copolimero polipirrol/polietilenglicol y polipirrol sintetizado por plasma

Energy Technology Data Exchange (ETDEWEB)

Colin, E.; Enriquez, M.A.; Olayo, M.G.; Cruz, G.J.; Carapia, L.; Romero, M. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Morales, J.; Olayo, R. [UAM-I, A.P. 55-534 Iztapalapa, Mexico D.F. (Mexico)

2006-07-01

In this work the study about the hydrolytic compatibility of semiconductor polymers, copolymer Poly pyrrole/ Polyethyleneglycol (PPy/PEG) and Poly pyrrole (PPy) for their possible use as biomaterials. The polymers were synthesized by plasma between 10 and 100 W, with discharges of splendor RF to 13.5 MHz with resistive coupling. The hydrolytic affinity was evaluated calculating the contact angle with solutions of NaCl, NaCl-MgSO{sub 4} and Krebs-Ringer. The results show a hydrophilicity increment due to the increase of the surface ruggedness with the synthesis energy. On the contrary, the crystallinity diminishes when increasing the power in PPy and it stays approximately constant in PPy/PEG. The electric conductivity presents a growth from 2 to 4 magnitude orders in function of the water content in the polymers. (Author)

Electrochemical polymerization of pyrrole over AZ31 Mg alloy for biomedical applications

International Nuclear Information System (INIS)

Srinivasan, A.; Ranjani, P.; Rajendran, N.

2013-01-01

Highlights: ► Polymerization of pyrrole over AZ31 Mg was carried out using cyclic voltammetry. ► Pyrrole concentration was optimized to accomplish the adherent and uniform coating. ► Effect of monomer concentration on the surface morphology was discussed. ► Corrosion resistance of AZ31 Mg in SBF was studied as a function of Py concentration. ► PPy coated AZ31 Mg alloy exhibited enhanced corrosion resistance at 0.25 M of Py. -- Abstract: Electrochemical polymerization of pyrrole (Py) from aqueous salicylate solution over AZ31 Mg alloy was carried out using cyclic voltammetry (CV). The effect of monomer concentration on the surface and electrochemical corrosion in simulated body fluid (SBF) were analysed. Attenuated total reflection-infrared (ATR-IR) spectra showed the characteristic ring stretching peaks for polypyrrole (PPy). Scanning electron microscopy (SEM) and atomic force microscopy (AFM) studies exhibited typical cauliflower morphology with rough surface for PPy coated AZ31 Mg alloy. Open circuit potential measurement and potentiodynamic polarization studies revealed that the coating prepared using 0.25 M of Py had positive shift of about 120 mV in corrosion potential and lower corrosion current density (0.03 mA/cm 2 ) compared to other concentrations and uncoated AZ31 Mg alloy (0.25 mA/cm 2 ). Electrochemical impedance spectroscopic (EIS) studies of uncoated and PPy coated Mg alloy in SBF revealed three-time constants behaviour with about one order of increment in impedance value for 0.25 M of Py

Pyrrole-regulated precipitation of titania nanorods on polymer fabrics for photocatalytic degradation of trace toluene in air

Science.gov (United States)

Gu, Yi-Jie; Wen, Wei; Xu, Yang; Wu, Jin-Ming

2018-03-01

When compared with nanoparticulate counterparts, TiO2 thin films with vertically aligned one-dimensional (1D) nanostructures exhibit enhanced photocatalytic activity because of the highly accessible surface area. The perpendicular of the 1D nanostructure reduces the charge migration path and hence the carrier recombination rate, which also contributes to the photocatalytic activity. Furthermore, TiO2 thin films on flexible substrates are more suitable to degrade pollutants in either water or air because of its easy recovery and free-bending shape. In this study, flexible polyethylene fabrics were firstly coated with a sol-gel nanoparticulate TiO2 seed layer. Quasi-aligned TiO2 nanorods were then precipitated homogeneously under an atmospheric pressure and a low temperature not exceeding 80 °C, using a peroxy-titanium complex precursor with the additive of pyrrole. It is found that the density of TiO2 nanorods increased with the increasing amount of pyrrole monomers. The resultant TiO2 film on polyethylene fabrics exhibited a much reduced band gap of ca. 2.86 eV, which can be attributed to the surface oxygen deficiencies. When utilized to assist photocatalytic degradation of trace toluene in air under the UV light illumination, the TiO2 film exhibited a gradually increased photocatalytic activity upon the increasing cycles for up to six, because of the gradual removal of trace organics on the TiO2 surface. The highest photocatalytic efficiency is recorded to be 5 times that of TiO2 nanotube arrays, which are regarded as an excellent photocatalyst for air cleaning.

Preparation of conductive membranes using poly pyrrole

International Nuclear Information System (INIS)

Madaeni, S.; Khavaran, B.

2003-01-01

Conductive membranes show many benefits including fouling reduction for feeds containing ionic species. These membranes may be prepared either by conductive polymers or coating of the surfaces of non-conductive membranes with conductive polymer. In this research, the commercial micro filtration GVHP membrane manufactured from PVDF was coated with poly pyrrole using two different techniques. The conductivity of the prepared membranes was measured. In this paper, effects of various factors including concentration of the solutions, oxidizing agents, time for leaving the support in the solutions, support type and temperature on membrane conductivity were investigated

A Submarine Journey: The Pyrrole-Imidazole Alkaloids

Directory of Open Access Journals (Sweden)

Alessandra Scolaro

2009-11-01

Full Text Available In his most celebrated tale “The Picture of Dorian Gray”, Oscar Wilde stated that “those who go beneath the surface do so at their peril”. This sentence could be a prophetical warning for the practitioner who voluntarily challenges himself with trying to synthesize marine sponge-deriving pyrrole-imidazole alkaloids. This now nearly triple-digit membered community has been growing exponentially in the last 20 years, both in terms of new representatives and topological complexity − from simple, achiral oroidin to the breathtaking 12-ring stylissadines A and B, each possessing 16 stereocenters. While the biosynthesis and the role in the sponge economy of most of these alkaloids still lies in the realm of speculations, significant biological activities for some of them have clearly emerged. This review will account for the progress in achieving the total synthesis of the more biologically enticing members of this class of natural products.

Oxidative coupling and polymerization of pyrroles

International Nuclear Information System (INIS)

Hansen, Gregers Hendrik; Henriksen, Rikke Morck; Kamounah, Fadhil S.; Lund, Torben; Hammerich, Ole

2005-01-01

The electrochemical oxidation of 2,4-dimethyl-3-ethylpyrrole in acetonitrile has been studied using cyclic voltammetry, constant current coulometry, preparative electrolyses and ab initio calculations. The product analysis after the preparative electrolyses was carried out by HPLC combined with UV-vis and electrospray ionization MS detection. The aim of the work was to address some of the unresolved problems in the oxidative oligomerization and polymerization of alkylpyrroles. The title compound was chosen as a model for studies of pyrroles that are more basic than the solvent-supporting electrolyte system and for that reason are forced to serve as the base accepting the protons released during the coupling steps. The voltammograms obtained by cyclic voltammetry at a substrate concentration of 2 mM and voltage scan rates between 0.02 and 2 V s -1 showed a characteristic trace-crossing phenomenon that could be demonstrated by digital simulation to be related to that fact that the deprotonations of the initially formed dimer dication are slow with second order rate constants in the range 10 3 -10 4 M -1 s -1 . The relative stability of the different tautomers of the protonated pyrrole monomer and the corresponding 2,2'-dimer was determined by ab initio calculations at the RHF 6-31G(d) level. The studies also included investigations of the effects resulting from addition of a non-nucleophilic base, 2,6-di-tert-butylpyridine, to the voltammetry solutions. The major product observed after preparative electrolyses was a trimer the structure of which is proposed to include a central 2H-pyrrole unit. Since 2H-pyrroles are stronger bases than the corresponding 1H-pyrroles, the trimer is effectively protected against further oxidation by protonation. Two other trimers were observed as minor or trace products as well as a 1H,2H-dimer and several tetramers, also in trace amounts. In addition to the dimer, the trimers and the tetramers, a number of other minor products could be

Synthesis of 14C analogue of 1,2-diaryl-[2-14C]-pyrroles

International Nuclear Information System (INIS)

Saemian, N.; Shirvani, G.; Matloubi, H.

2007-01-01

Three 1,2-diaryl pyrroles selective COX-2 inhibitors, 2-(4-fluorophenyl)-5-methyl-1-(4-methylsulfonyl-phenyl)-1H pyrrole, 2-(4-fluorophenyl)-1- [4-(methylsulfonyl) phenyl]-1H-pyrrole and 4-[2-(4-fluorophenyl)-1H-pyrrol-1-yl]benzenesulfon-amide, all three labeled with 14 C in the 2-position were prepared from para-fluoro-benzaldehyde-[carbonyl- 14 C]. (author)

The electrochemical synthesis of poly(pyrrole-co-o-anisidine) on 3102 aluminum alloy and its corrosion protection properties

International Nuclear Information System (INIS)

Mert, B. Dogru; Yazici, B.

2011-01-01

Research highlights: → The electrochemical synthesis of strongly adherent, uniform polypyrrole (PPy) and poly(pyrrole-co-o-anisidine) coatings were successfully achieved on 3102 aluminum alloy from 0.1 M monomer (pyrrole and pyrrole:o-anisidine, 8:2) containing oxalic acid by means of the cyclic voltammetry technique. → The results were showed that the water permeation of copolymer coating is lower than PPy. → This study was showed that copolymer is suitable coating for protection of 3102 Al alloy against corrosion. - Abstract: The electrochemical syntheses of polypyrrole (PPy) and poly(pyrrole-co-o-anisidine) were achieved on 3102 aluminum alloy (Al) from 0.1 M monomer (pyrrole:o-anisidine, 8:2) containing 0.4 M oxalic acid solution using the cyclic voltammetry technique. The synthesized films were characterized by FT-IR spectroscopy. The thermal stability of films was determined by thermogravimetric analysis (TGA) technique. Surface morphologies were characterized by scanning electron microscope (SEM) images. The potential of zero charge (pzc) of Al was determined using electrochemical impedance spectroscopy (EIS). The corrosion behavior of samples was investigated with open circuit potential (E ocp )-time, EIS, and anodic polarization techniques. It was found that copolymer coated Al provides better barrier property against of corrosion in 3.5% NaCl solution.

Synthesis and characterisation of new Schiff base monomers containing N-(alkyl and phenyl) pyrrole moieties

Science.gov (United States)

Amer, Ahcene Ait; Ilikti, Hocine; Maschke, Ulrich

2017-11-01

This article deals with the synthesis and characterisation of seven new functional Schiff base monomers, such as: M1: 1-(3-Pyrrole-1-yl-propylimino-methyl)-naphtalen-2-ol; M2: 2-(3-Pyrrole-1-yl-phenylimino-methyl)-phenol; M3: 1-(3-Pyrrole-1-yl-phenylimino-methyl)-naphtalen-2-ol; M4: N-(pyridin-2-yl-methylene)-2-(pyrrol-1-yl)-benzenamine; M5: N-(pyridin-2-yl-methylene)-3-(pyrrol-1-yl)-propan-1-amine; M6: 2-(3-pyrrol-1-yl-propylimino-methyl)-quinolin-8-ol; M7: 2-(3-pyrrol-1-yl-phenylimino-methyl)-quinolin-8-ol. Two series of compounds emerged from this study, N-propyl pyrrole derivatives (M1, M5, M6) and N-phenyl pyrrole compounds (M2, M3, M4, M7). All monomers were elaborated by condensation reactions between appropriate amines and aldehydes, and their molecular structures were confirmed by spectroscopic analysis methods like FT-IR, 1H NMR, 13C NMR, and GC-MS.

STUDY OF ELECTROPOLIMERIZATION PROCESSES OF PYRROLE BY CYCLIC VOLTAMMETRIC TECHNIQUE

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Adhitasari Suratman

2010-06-01

Full Text Available Electropolymerization processes and electrochemical properties of polypyrrole as electroactive polymer have been studied by cyclic voltammetric technique. Pyrrole was electropolymerized to form polypyrrole in water-based solvent containing sodium perchlorate as supporting electrolyte in several pH values. The pH of the solutions were varied by using Britton Robinson buffer. The results showed that oxidation potential limit of electropolymerization processes of pyrrole was 1220 mV vs Ag/AgCl reference electrode. It can be seen that cyclic voltammetric respon of polypyrrole membrane that was prepared by electropolymerization processes of pyrrole at the scanning rate of 100 mV/s was stable. While the processes of pyrrole electropolymerization carried out at the variation of pH showed that the best condition was at the pH range of 2 - 6.   Keywords: polypyrolle, electropolymer, voltammetric technique

An Efficient and Short Route for the Synthesis of Reverse Pyrrole Ribonucleosides

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Pereira Letícia O. R.

2002-01-01

Full Text Available The synthesis of reverse pyrrole ribonucleosides methyl 5-C-(4-acetyl-5-methyl-pyrrol-1-yl-2,3-O-isopropylidene-5-deoxy- beta-D-ribofuranoside (10, methyl 5-C-(4-ethoxycarbonyl-5-methyl-pyrrol-1-yl-2,3-O-isopropylidene-5-deoxy- beta-D-ribofuranoside (11, methyl 5-C-(4-acetyl-5-methyl-pyrrol-1-yl-5-deoxy-beta-D-ribofuranoside (12, methyl 5-C-(4-ethoxycarbonyl-5-methyl-pyrrol-1-yl-5-deoxy- beta-D-ribofuranoside (13, methyl 5-deoxy-5-C-(3'-formyl-4'-hydroxypropyl-pyrrol-1'-yl-2,3-O-isopropylidene- beta-D-ribofuranoside (16 and methyl 5-deoxy-5-C-(3'-formyl-pyrrol-1'-yl-2,3-O-isopropylidene- beta-D-ribofuranoside (18 are described starting from readily available methyl 5-amino-5-deoxy-2,3-O-isopropylidene-beta-D-ribofuranoside (9. The synthetic strategy for the construction of the heterocyclic ring was based on the nucleophilic attack of (9 to 4-acetyl-2-n-butoxy-5-methyl-4,5-dihydrofuran (4, 4-carbetoxy-2-n-butoxy-5-methyl-4,5-dihydrofuran (5, 4-formyl-2-n-butoxy-4,5-dihydrofuran (6 and 4-formyl-1-methyl dioxabyciclo[3.3.0]oct-3-en (8, in situ. The later compounds were obtained from reaction between 3-diazo-2,4-pentadione (1, ethyl 2-diazoacetoacetate (2 or diazomalonaldehyde (3 and enol ethers using dirhodium tetraacetate as a catalyst.

Computational study on the functionalization of BNNC with pyrrole molecule

Science.gov (United States)

Payvand, Akram; Tavangar, Zahra

2018-05-01

The functionalization of the boron nitride nanocone (BNNC) by pyrrole molecule was studied using B3LYP/6-311+G(d) level of theory. The reaction was studied in three methods in different layers of the nanocone: Diels-Alder cycloaddition, quartet cycloaddition and the reaction of the nitrogen atom of the pyrrole molecule with the boron or nitrogen atom of the BNNC. Thermodynamic quantities, Chemical hardness and potential and electrophilicity index of the functionalized BNNC were studied. The results show that the tip of nanocone has a higher tendency for participation in the reaction and the most favorable product of the reaction between BNNC and pyrrole molecule is produced from the reaction of N atom of pyrrole with the B atom of BNNC. The reaction decreases the energy gap value which leads to increasing the reactivity and conductivity of functionalized nanocone. The calculated NICS values confirm the aromaticity in the pristine nanocone as well as in the functionalized nanocone.

Polycondensation of pyrrole and benzaldehyde catalyzed by Maghnite–H+

Directory of Open Access Journals (Sweden)

2007-07-01

Full Text Available Rapid synthesis of poly[(pyrrole-2,5-diyl-co-(benzylidene] was achieved under microwave irradiation via the condensation of pyrrole and benzaldehyde in 1,2-dichloroethane using acid exchanged montmorillonite clay called Maghnite–H+ (Mag–H+ as an efficient catalyst. The effect of the amount of catalyst and of time on the polymerization yield and on the viscosity of the polymers was studied. Compared with conventional static interfacial polymerization, the microwave-radiation polymerization reaction proceeded rapidly and was completed within 35 s. The conjugated polymer was characterized by means of 1H-NMR, X-ray diffraction, FT-IR spectroscopy and AFM. The X-ray data showed the presence of a backbone form of the [(pyrrole-2,5-diyl-co-(benzylidene] formed.

Spectroscopic and theoretical studies on the aromaticity of pyrrol-2-yl-carbonyl conformers

Science.gov (United States)

Dubis, Alina T.; Wojtulewski, Sławomir; Filipkowski, Karol

2013-06-01

The aromaticity of s-cis and s-trans pyrrol-2-yl carbonyl conformers was studied by FT-IR, 1H NMR spectroscopy and DFT calculations at the B3LYP/6-311++G(d,p) level of theory. The Harmonic Oscillator Model of Aromaticity (HOMA) and Nucleus Independent Chemical Shift (NICS) indices were calculated to estimate π-electron delocalization in the pyrrole ring. The usefulness of infrared spectroscopy in the evaluation of the aromaticity of the homogeneous set of pyrroles is discussed. The influence of 2-substitution on different aspects of aromaticity and stability of the pyrrol-2-yl carbonyl conformers is also discussed. It is concluded that the substitution effect of the title pyrrole derivatives can be explained on the basis of theoretical and experimental measurements of π-electron delocalization, including IR data.

Effect of alkali metal ions on the pyrrole and pyridine π-electron systems in pyrrole-2-carboxylate and pyridine-2-carboxylate molecules: FT-IR, FT-Raman, NMR and theoretical studies

Science.gov (United States)

Świderski, G.; Wojtulewski, S.; Kalinowska, M.; Świsłocka, R.; Lewandowski, W.

2011-05-01

The FT-IR, FT-Raman and 1H and 13C NMR spectra of pyrrole-2-carboxylic acid (PCA) and lithium, sodium, potassium, rubidium and caesium pyrrole-2-carboxylates were recorded, assigned and compared in the Li → Na → K → Rb → Cs salt series. The effect of alkali metal ions on the electronic system of ligands was discussed. The obtained results were compared with previously reported ones for pyridine-2-carboxylic acid and alkali metal pyridine-2-carboxylates. Calculations for pyrrole-2-carboxylic acid and Li, Na, K pyrrole-2-carboxylates in B3LYP/6-311++G ** level and Møller-Plesset method in MP2/6-311++G ** level were made. Bond lengths, angles and dipole moments as well as aromaticity indices (HOMA, EN, GEO, I 6) for the optimized structures of pyrrole-2-carboxylic acid (PCA) and lithium, sodium, potassium pyrrole-2-carboxylates were also calculated. The degree of perturbation of the aromatic system of ligand under the influence of metals in the Li → Cs series was investigated with the use of statistical methods (linear correlation), calculated aromaticity indices and Mulliken, NBO and ChelpG population analysis method. Additionally, the Bader theory (AIM) was applied to setting the characteristic of the bond critical points what confirmed the influence of alkali metals on the pyrrole ring.

Numerical Analysis Of Hooke Jeeves-Runge Kutta To Determine Reaction Rate Equation In Pyrrole Polymerization

International Nuclear Information System (INIS)

Gunawan, Indra; Sulistyo, Harry; Rochmad

2001-01-01

The numerical analysis of Hooke Jeeves Methods combined with Runge Kutta Methods is used to determine the exact model of reaction rate equation of pyrrole polymerization. Chemical polymerization of pyrrole was conducted with FeCI 3 / pyrrole solution at concentration ratio of 1.62 mole / mole and 2.18 mole / mole with varrying temperature of 28, 40, 50, and 60 o C. FeCl 3 acts as an oxidation agent to form pyrrole cation that will polymerize. The numerical analysis was done to examine the exact model of reaction rate equation which is derived from reaction equation of initiation, propagation, and termination. From its numerical analysis, it is found that the pyrrole polymerization follows third order of pyrrole cation concentration

Preparation of ultrathin pyrrolic conductor films as backings of radioactive sources

International Nuclear Information System (INIS)

Rodriguez, L.; Los Arcos, J.M.

1993-01-01

A procedure for electropolymerization of pyrrole has been set up in order to produce thin (> 15 μ g/cm 2 ) homogeneous (thickness variation 2 . The experimental equipment, reagent and procedure utilized is described as well as the characterization pyrrolic films produced

Biofunctionalization of multiwalled carbon nanotubes by irradiation of electropolymerized poly(pyrrole-diazirine) films.

Science.gov (United States)

Papper, Vladislav; Gorgy, Karine; Elouarzaki, Kamal; Sukharaharja, Ayrine; Cosnier, Serge; Marks, Robert S

2013-07-15

A photoactivatable poly(pyrrole-diazirine) film was synthesized and electropolymerized as a versatile tool for covalent binding of laccase and glucose oxidase on multiwalled carbon nanotube coatings and Pt, respectively. Irradiation of the functionalized nanotubes allowed photochemical grafting of laccase and its subsequent direct electrical wiring, as illustrated by the electrocatalytic reduction of oxygen. Moreover, covalent binding of glucose oxidase as model enzyme, achieved by UV activation of electropolymerized pyrrole-diazirine, allowed a glucose biosensor to be realized. This original method to graft biomolecules combines electrochemical and photochemical techniques. The simplicity of this new method allows it to be extended easily to other biological systems. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Theoretical study of structure and electronic properties of cyano-substituted pyrroles

International Nuclear Information System (INIS)

Rimarcik, Jan; Lukes, Vladimir; Klein, Erik; Griesser, Markus; Kelterer, Anne-Marie

2008-01-01

DFT and ab initio MP2 calculations of optimal geometries, dipole moments, polarizabilities, excitation energies and enthalpies of hydrogen or proton transfer from N-H group for cyano derivatives of pyrrole are presented. CN groups in α and β positions have distinct effects on electron spectra absorption bands. CN in α position causes larger bathochromic shift in comparison to β position. N-H bond dissociation enthalpies (BDE) of substituted pyrroles are higher by 7 kJ mol -1 than pyrrole BDE. Number and position of CN groups do not affect BDEs. Proton affinities of pyrrolyl anions and enthalpies of electron transfer from these anions are proportional to the number of CN groups in molecule. Each CN group causes decrease in proton affinity by 72 kJ mol -1 and 73 kJ mol -1 rise in electron transfer enthalpy. For several studied pyrroles, BDEs, proton affinities and electron transfer enthalpies in water and benzene were computed

Biofunctionalization of multiwalled carbon nanotubes by electropolymerized poly(pyrrole-concanavalin A) films.

Science.gov (United States)

Papper, Vladislav; Elouarzaki, Kamal; Gorgy, Karine; Sukharaharja, Ayrine; Cosnier, Serge; Marks, Robert S

2014-10-13

The synthesis and electropolymerization of a pyrrolic concanavalin A derivative (pyrrole-Con A) onto a multiwalled carbon nanotube (MWCNT) deposit is reported. Glucose oxidase was then immobilized onto the MWCNT-poly(pyrrole-Con A) coating by affinity carbohydrate interactions with the polymerized Con A protein. The resulting enzyme electrode was applied to the amperometric detection of glucose exhibiting a high sensitivity of 36 mA cm(-2) mol(-1) L and a maximum current density of 350 μA cm(-2) . © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Very Strong Binding for a Neutral Calix[4]pyrrole Receptor Displaying Positive Allosteric Binding

DEFF Research Database (Denmark)

Duedal, Troels; Nielsen, Kent; Olsen, Gunnar

2017-01-01

. The tetrathiafulvalene (TTF) subunits in the tetraTTF-calix[4]pyrrole receptor 1 present a nearly perfect shape and electronic complementarity to the NTCDA guest, which was confirmed by X-ray crystal structure analysis, DFT calculations, and electron density surface mapping. The complexation results in formation...... of a charge transfer complex (22⊆1), that is visualized as a color change from yellow to brown....

2,5-Dimethyl-1-phenylsulfonyl-1H-pyrrole-3,4-dicarbaldehyde

Directory of Open Access Journals (Sweden)

2009-03-01

Full Text Available In the title compound, C14H13NO4S, the mean planes of the pyrrole and phenyl rings form a dihedral angle of 88.7 (1°. The aldehyde groups are slightly twisted from the pyrrole plane. In the crystal structure, molecules are linked into a three-dimensional framework by C—H...O hydrogen bonds.

Sustainable Pathways to Pyrroles through Iron-Catalyzed N-Heterocyclization from Unsaturated Diols and Primary Amines

NARCIS (Netherlands)

Yan, Tao; Barta, Katalin

2016-01-01

Pyrroles are prominent scaffolds in pharmaceutically active compounds and play an important role in medicinal chemistry. Therefore, the development of new, atom-economic, and sustainable catalytic strategies to obtain these moieties is highly desired. Direct catalytic pathways that utilize readily

Strapped Calix[4]pyrroles Bearing an 1,3-Indanedione at a β-Pyrrolic Position: Chemodosimeters for the Cyanide Anion

Science.gov (United States)

Kim, Sook-Hee; Hong, Seong-Jin; Yoo, Jaeduk; Kim, Sung Kuk; Sessler, Janathan L.; Lee, Chang-Hee

2014-01-01

A strapped calix[4]pyrrole bearing an 1,3-indanedione group at a β-pyrrolic position has been synthesized and studied as a ratiometric cyanide selective chemosensor. A concentration-dependent bleaching of the initial yellow color was observed upon addition of the cyanide anion. The bleaching, which was observed exclusively with the cyanide anion, occurred even in the presence of other anions. Spectroscopic studies provides support for a mechanistic interpretation wherein the cyanide anion forms a complex with the receptor (K = 2.78 × 104 M-1) through a fast equilibrium, which is followed by slow nucleophilic addition to the β-position of the 1,3-indanedione group. A minimum inhibitory effect from other anions was observed, a feature that could be beneficial in the selective sensing of the cyanide anion. PMID:19639968

5-Imino-3,4-diphenyl-1H-pyrrol-2-one

Science.gov (United States)

Bulatov, Evgeny; Chulkova, Tatiana; Haukka, Matti

2014-01-01

The title compound, C16H12N2O, exists in the crystalline state as the 5-imino-3,4-di­phenyl­-1H-pyrrol-2-one tautomer. The dihedral angles between the pyrrole and phenyl rings are 35.3 (2) and 55.3 (2)°. In the crystal, inversion dimers linked by pairs of N—H⋯N hydrogen bonds generate a graph-set motif of R 2 2(8) via N—H⋯N hydrogen bonds. PMID:24764881

5-Imino-3,4-diphenyl-1H-pyrrol-2-one

Directory of Open Access Journals (Sweden)

Evgeny Bulatov

2014-02-01

Full Text Available The title compound, C16H12N2O, exists in the crystalline state as the 5-imino-3,4-diphenyl-1H-pyrrol-2-one tautomer. The dihedral angles between the pyrrole and phenyl rings are 35.3 (2 and 55.3 (2°. In the crystal, inversion dimers linked by pairs of N—H...N hydrogen bonds generate a graph-set motif of R22(8 via N—H...N hydrogen bonds.

Oxoanion Recognition by Benzene-based Tripodal Pyrrolic Receptors

Energy Technology Data Exchange (ETDEWEB)

Bill, Nathan [University of Texas at Austin; Kim, Dae-Sik [University of Texas at Austin; Kim, Sung Kuk [University of Texas at Austin; Park, Jung Su [University of Texas at Austin; Lynch, Vincent M. [University of Texas at Austin; Young, Neil J [ORNL; Hay, Benjamin [ORNL; Yang, Youjun [University of Texas at Austin; Anslyn, Eric [University of Texas at Austin; Sessler, Jonathan L. [University of Texas

2012-01-01

Two new tripodal receptors based on pyrrole- and dipyrromethane-functionalised derivatives of a sterically geared precursor, 1,3,5-tris(aminomethyl)-2,4,6-triethylbenzene, are reported; these systems, compounds 1 and 2, display high affinity and selectivity for tetrahedral anionic guests, in particular dihydrogen phosphate, pyrophosphate and hydrogen sulphate, in acetonitrile as inferred from isothermal titration calorimetry measurements. Support for the anion-binding ability of these systems comes from theoretical calculations and a single-crystal X-ray diffraction structure of the 2:2 (host:guest) dihydrogen phosphate complex is obtained in the case of the pyrrole-based receptor system, 1. Keywords anion receptors, dihydrogen phosphate, hydrogen sulphate, X-ray structure, theoretical calculations.

Electrografting of in situ generated pyrrole derivative diazonium salt for the surface modification of nickel

International Nuclear Information System (INIS)

Jacques, A.; Devillers, S.; Delhalle, J.; Mekhalif, Z.

2013-01-01

Highlights: • Electrografting of in situ generated 4-pyrrolylphenyldiazonium (Py-PD) on Ni. • Generation of Py-PD from 4-pyrrolylaniline in 3 acidic conditions followed by UV. • XPS and SEM confirm efficiency, reproducibility and homogeneity of the grafting. • Electrografting process assessed by CV. • Barrier properties of the grafted film evidenced by CV. -- Abstract: This work reports for the first time on the modification of nickel surfaces by cathodic electrografting of in situ generated diazonium. An original diazonium salt (the 4-pyrrolylphenyldiazonium called Py-PD hereafter) was electrografted on nickel after its generation from 4-(1H-pyrrol-1-yl)aniline (Py-A) in presence of three acidic conditions (1, 2 and 10 equiv. of HClO 4 /Py-A) has been investigated by UV–vis spectroscopy. Results show that the potentiostatic electrografting of Py-PD is concomitant with nickel and proton reduction. This electrografting leads to the formation of multilayered films in each of the studied in situ generation conditions. The use of 1 equiv. of HClO 4 /Py-A for the in situ generation results in the formation of inhomogeneous and irreproducible coatings while 2 and 10 equiv. lead to the formation of highly covering, homogeneous and reproducible films. These films present good electrochemical barrier properties toward the ferri/ferrocyanide couple. The use of gentle stoichiometric acidic conditions for in situ diazonium generation widens the application field of this one-step procedure to the surface modification of oxidizable materials presenting an unstable oxide layer

Poly(1-(2-carboxyethyl)pyrrole)/polypyrrole composite nanowires for glucose biosensor

International Nuclear Information System (INIS)

Jiang Hairong; Zhang Aifeng; Sun Yanan; Ru Xiaoning; Ge Dongtao; Shi Wei

2012-01-01

A novel glucose biosensor based on poly(1-(2-carboxyethyl)pyrrole) (PPyCOOH)/polypyrrole (PPy) composite nanowires was developed by immobilizing glucose oxidase (GOD) on the nanowires via covalent linkages. The PPyCOOH/PPy composite nanowires were fabricated by a facile two-step electrochemical synthesis route. First, PPy nanowires were synthesized in phosphate buffer solution using organic sulfonic acid, p-toluenesulfonate acid, as soft-template. Then, PPyCOOH/PPy composite nanowires were obtained by polymerizing 1-(2-carboxyethyl)pyrrole onto PPy nanowires via electrochemical method. Scanning electron microscopic, FT-IR spectra, X-ray photoelectron spectroscopy and cyclic voltammograms were used to characterize the structural and electrical behaviors of the composite nanowires. The PPyCOOH/PPy composite nanowires exhibited uniform diameter, high reactive site (-COOH), large specific surface, excellent electroactivity and good adhesion to electrode. The glucose biosensor was constructed by covalently coupling GOD to the composite nanowires. The biosensor response was rapid (5 s), highly sensitive (33.6 μA mM −1 cm −2 ) with a wide linear range (up to 10.0 mM) and low detection limit (0.63 μM); it also exhibited high stability and specificity to glucose. The attractive electrochemical and structural properties of PPyCOOH/PPy composite nanowires suggested potential application for electrocatalysis and biosensor.

Silica sulfuric acid: a reusable solid catalyst for one pot synthesis of densely substituted pyrrole-fused isocoumarins under solvent-free conditions

Directory of Open Access Journals (Sweden)

Sudipta Pathak

2013-11-01

Full Text Available A convenient and efficient methodology for the synthesis of densely substituted pyrrole-fused isocoumarins, which employs solid-supported silica sulfuric acid (SSA as catalyst, has been developed. When the mixture of ninhydrin adducts of acetylacetone/ethyl acetoacetate and primary amines was heated on the solid surface of SSA under solvent-free conditions, the pyrrole-fused isocoumarins were formed in good yields. This synthetic method has several advantages such as the employment of solvent-free reaction conditions without the use of any toxic reagents and metal catalysts, the ease of product isolation, the use of a recyclable catalyst, the low cost, the easy availability of the starting materials, and the excellent yields of products.

Hydroquinone–pyrrole dyads with varied linkers

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Hao Huang

2016-01-01

Full Text Available A series of pyrroles functionalized in the 3-position with p-dimethoxybenzene via various linkers (CH2, CH2CH2, CH=CH, C≡C has been synthesized. Their electronic properties have been deduced from 1H NMR, 13C NMR, and UV–vis spectra to detect possible interactions between the two aromatic subunits. The extent of conjugation between the subunits is largely controlled by the nature of the linker, with the largest conjugation found with the trans-ethene linker and the weakest with the aliphatic linkers. DFT calculations revealed substantial changes in the HOMO–LUMO gap that correlated with the extent of conjugation found experimentally. The results of this work are expected to open up for use of the investigated compounds as components of redox-active materials in sustainable, organic electrical energy storage devices.

Synthesis and Physical Characterization of Carbon Nano tubes Coated by Conducting Poly pyrrole

International Nuclear Information System (INIS)

Talib, A.B.Z.A.; Wan Mahmood Mat Yunus; Kasar Behzad; Nayereh Soltani

2011-01-01

This study describes the preparation of poly pyrrole multi walled carbon nano tube (PPy/ MWNT) composites by in situ chemical oxidative polymerization. Various ratios of functionalized MWNTs are dispersed in the water, and PPy are then synthesized via in-situ chemical oxidative polymerization on the surface of the carbon nano tubes. The morphology of the resulting complex nano tubes (MWNT-PPY) was characterized by scanning electron microscopy (SEM). The conductivity of each composite showed a maximum in the temperature scale of 120- 160 degree Celsius and then decreased dramatically with the increase of temperature. (author)

Electrochemical synthesis of poly(pyrrole-co-o-anisidine)/chitosan composite films

Science.gov (United States)

Yalçınkaya, Süleyman; Çakmak, Didem

2017-05-01

In this study, poly(pyrrole-co-o-anisidine)/chitosan composite films were electrochemically synthesized in various monomers feed ratio (pyrrole: o-anisidine; 9:1, 7:3, 1:1, 3:7 and 1:9) of pyrrole and o-anisidine on the platinum electrode. Electrochemical synthesis of the composite films was carried out via cyclic voltammetry technique. They were characterized by FT-IR, cyclic voltammetry, SEM micrographs, digital images, TGA and DSC techniques. The SEM results indicated that the particle size of the composite decreased with increasing o-anisidine ratio and the films became more likely to be smooth morphology. The TGA results proved that the film of the composite with 1:1 ratio showed highest final degradation temperature and lowest weight loss (83%) compared to copolymer and 9:1 1:9 composite films. The 1:1 composite film had higher thermal stability than copolymer and the other composite films (9:1 1:9). Meanwhile, electrochemical studies exhibited that the 1/9 composite film had good electrochemical stability as well.

Knorr-Rabe partial reduction of pyrroles: Application to the synthesis of indolizidine alkaloids

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Ryan John H

2008-01-01

Full Text Available Abstract Background The Birch reduction of electron rich pyrroles does not occur readily. However, dissolving metal reduction with zinc under acidic conditions gives 3-pyrrolines (2,5-dihydropyrroles in reasonable yield. This dissolving metal reduction was first reported by Knorr and Rabe in 1901 but since then has only been reported for the reduction of electron rich pyrroles. Results The partial reduction of bicyclic α-ketopyrrole derivatives has been performed under dissolving metal conditions with zinc and hydrochloric acid to give excellent yields of hexahydroindolizidines. This reduction method has been utilised for the diastereoselective synthesis of 5-alkylindolizidines and the stereoselectivity obtained is opposite to that of catalytic hydrogenation. Conclusion An efficient stereoselective synthesis of indolizidine alkaloids has been developed from α-ketopyrrole intermediates using a modified version of Knorr and Rabe's pyrrole reduction.

Blood Pyrrole-Protein Adducts--A Biomarker of Pyrrolizidine Alkaloid-Induced Liver Injury in Humans.

Science.gov (United States)

Ruan, Jianqing; Gao, Hong; Li, Na; Xue, Junyi; Chen, Jie; Ke, Changqiang; Ye, Yang; Fu, Peter Pi-Cheng; Zheng, Jiang; Wang, Jiyao; Lin, Ge

2015-01-01

Pyrrolizidine alkaloids (PAs) induce liver injury (PA-ILI) and is very likely to contribute significantly to drug-induced liver injury (DILI). In this study we used a newly developed ultra-high performance liquid chromatography-triple quadrupole-mass spectrometry (UHPLC-MS)-based method to detect and quantitate blood pyrrole-protein adducts in DILI patients. Among the 46 suspected DILI patients, 15 were identified as PA-ILI by the identification of PA-containing herbs exposed. Blood pyrrole-protein adducts were detected in all PA-ILI patients (100%). These results confirm that PA-ILI is one of the major causes of DILI and that blood pyrrole-protein adducts quantitated by the newly developed UHPLC-MS method can serve as a specific biomarker of PA-ILI.

Self-association and infrared spectres of some heterocyclic compounds based on pyrrol in solid state

International Nuclear Information System (INIS)

Mulloev, N.; Nurulloev, M.; Narziev, B.N.

1993-01-01

Present article is devoted to self-association and infrared spectres of some heterocyclic compounds based on pyrrol in solid state. The study results of self-association specified by molecular hydrogen bonds of some heterocyclic compounds based on pyrrol on spectres of infrared absorption of stretching vibrations of N-H group were considered.

Gamma irradiation effect on polymers derived of pyrrole synthesized by plasma

International Nuclear Information System (INIS)

Lopez G, O. G.

2013-01-01

This work studies the effect of gamma irradiation at doses of 50, 100, 200, 400 and 800 kGy on polymers obtained from pyrrole synthesized by plasma. The evolution of the structure was studied by Fourier transform infrared spectroscopy (Ftir) and X-ray photoelectron spectroscopy (XPS). The Ftir spectra show that poly pyrroles have N-H, C-H, C=O, triple and consecutive double bonds in their structure. The irradiated polymers show the same chemical groups in their structure without significant changes. Nevertheless, a more detailed analysis by XPS allows the identification of superficial chemical states, such as: C=CH-C, C=CC-C, C-NH-C, C-NC-C, etc., and shows that most of these states are present in all polymers but with different participation. One possible mechanism indicates that as the irradiation dose increases, dehydrogenation processes are performed increasing fragmentation, crosslinking and formation of multiple bonds. The fragmentation and thermal degradation were studied by thermogravimetric analysis, indicating that the loss of moisture and light compounds formed during gamma irradiation occurs in the firsts 100 grades C. The main degradation of all polymers occurs from 150 to 700 grades C, suggesting that the thermal stability is independent of the irradiation dose in the interval studied. Morphology was studied using scanning electron microscopy techniques. Before irradiation, the polymer presented a uniform and practically smooth surface, however, after gamma irradiation, the applied energy increased roughness and macro fragmentation. The roughness and functional groups on the surface reduced the contact angle with water as the irradiation dose increased. However, the polymers are hydrophilic, because for all doses that contact angle is smaller than 90 grades C. Electrical conductivity was calculated respect to temperature in the interval from 25 to 100 grades C. Conductivity increases with temperature and is slightly greater in the irradiated polymers

Towards physical interpretation of substituent effects: the case of N- and C3-substituted pyrrole derivatives

Czech Academy of Sciences Publication Activity Database

Zborowski, K. K.; Szatylowicz, H.; Stasyuk, Olga A.; Krygowski, T. M.

2017-01-01

Roč. 28, č. 4 (2017), s. 1223-1227 ISSN 1040-0400 Institutional support: RVO:61388963 Keywords : substituent effect * pyrrole derivatives * Hammett equation * charges of the substituent active region Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.582, year: 2016 https://link.springer.com/article/10.1007%2Fs11224-017-0938-7

Imidazopyridine/Pyrrole and hydroxybenzimidazole/pyrrole pairs for DNA minor groove recognition.

Science.gov (United States)

Renneberg, Dorte; Dervan, Peter B

2003-05-14

The DNA binding properties of fused heterocycles imidazo[4,5-b]pyridine (Ip) and hydroxybenzimidazole (Hz) paired with pyrrole (Py) in eight-ring hairpin polyamides are reported. The recognition profile of Ip/Py and Hz/Py pairs were compared to the five-membered ring pairs Im/Py and Hp/Py on a DNA restriction fragment at four 6-base pair recognition sites which vary at a single position 5'-TGTNTA-3', where N = G, C, T, A. The Ip/Py pair distinguishes G.C from C.G, T.A, and A.T, and the Hz/Py pair distinguishes T.A from A.T, G.C, and C.G, affording a new set of heterocycle pairs to target the four Watson-Crick base pairs in the minor groove of DNA.

meso-Octamethylcalix[4]pyrrole as an effective macrocyclic receptor for the univalent thallium cation in the gas phase: Experimental and theoretical study

Science.gov (United States)

Polášek, Miroslav; Makrlík, Emanuel; Kvíčala, Jaroslav; Křížová, Věra; Vaňura, Petr

2018-02-01

By using electrospray ionization mass spectrometry (ESI-MS), it was proven experimentally that the univalent thallium cation (Tl+) forms with meso-octamethylcalix[4]pyrrole (1) the cationic complex species 1 Tl+. When this kinetically stable cation-π complex 1 Tl+ is collisionally activated, it decomposes by elimination of the whole ligand 1 or small meso-octamethylcalix[4]pyrrole fragments. Further, applying quantum chemical DFT calculations, four different conformations of the resulting complex 1 Tl+ were derived. It means that under the present experimental conditions, this ligand 1 can be considered as a very effective macrocyclic receptor for the thallium cation.

Grinding solvent-free Paal-Knorr pyrrole synthesis on smectites as ...

African Journals Online (AJOL)

Journal Home > Vol 32, No 1 (2018) > ... An environmentally benign method for the synthesis of N-substituted pyrroles from one-pot solvent-free ... conditions make this protocol practical, environmentally friendly and economically attractive.

Conducting polymers of decanedioic acid bis-(4-pyrrol-1-yl-phenyl) ester

International Nuclear Information System (INIS)

Cirpan, A.; Guner, Y.; Toppare, L.

2004-01-01

A dipyrrolyl monomer was synthesized via the reaction between 4-pyrrol-1-yl phenol and decanedioyl dichloride. The electrochemical behavior of this monomer was studied. Polymerization of decanedioic acid bis-(4-pyrrol-1-yl-phenyl) ester (DAPE) was achieved by chemical and constant current electrolyses methods. Copolymerization of DAPE with thiophene was performed by constant potential electrolysis in acetonitrile-tetrabutylammonium tetrafluoroborate (TBAFB), dichloromethane-TBAFB, solvent-electrolyte couples. The chemical structures and properties were investigated by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, differential scanning calorimetry and thermal gravimetry analysis. The conductivities of the samples were measured by a four-probe technique

Conducting polymers of decanedioic acid bis-(4-pyrrol-1-yl-phenyl) ester

Energy Technology Data Exchange (ETDEWEB)

Cirpan, A.; Guner, Y.; Toppare, L

2004-05-15

A dipyrrolyl monomer was synthesized via the reaction between 4-pyrrol-1-yl phenol and decanedioyl dichloride. The electrochemical behavior of this monomer was studied. Polymerization of decanedioic acid bis-(4-pyrrol-1-yl-phenyl) ester (DAPE) was achieved by chemical and constant current electrolyses methods. Copolymerization of DAPE with thiophene was performed by constant potential electrolysis in acetonitrile-tetrabutylammonium tetrafluoroborate (TBAFB), dichloromethane-TBAFB, solvent-electrolyte couples. The chemical structures and properties were investigated by Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, differential scanning calorimetry and thermal gravimetry analysis. The conductivities of the samples were measured by a four-probe technique.

Regioselective C2 Oxidative Olefination of Indoles and Pyrroles through Cationic Rhodium(III)-Catalyzed C-H Bond Activation.

Science.gov (United States)

Li, Bin; Ma, Jianfeng; Xie, Weijia; Song, Haibin; Xu, Shansheng; Wang, Baiquan

2013-09-02

Be economic with your atoms! An efficient Rh-catalyzed oxidative olefination of indoles and pyrroles with broad substrate scope and tolerance is reported. The catalytic reaction proceeds with excellent regio- and stereoselectivity. The directing group N,N-dimethylcarbamoyl was crucial for the reaction and could be removed easily. Copyright © 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim.

A colorimetric tetrathiafulvalene-calix 4 pyrrole anion sensor

DEFF Research Database (Denmark)

Nielsen, K. A.

2012-01-01

The interaction and colorimetric sensing properties of a tetrathiafulvalene substituted calix[4]pyrrole sensor with anions were investigated using H-1 NMR and absorption spectroscopic techniques. Visual color changes were observed upon addition of different anions (Cl-, Br-, CN-, and Ac......O-) to a solution of the sensor. (C) 2012 Elsevier Ltd. All rights reserved....

Self-Assembly of Dimeric Tetrathiafulvalene-Calix 4 pyrrole: Receptor for 1,375-Trinitrobenzene

DEFF Research Database (Denmark)

Nielsen, K. A.; Stein, P. C.

2011-01-01

The synthesis and binding properties of a tetrathiafulvalene (TTF)-calix[4]pyrrole receptor 2 appended with one 3,5-dinitrobenzoate guest moiety are reported. The preliminary studies revealed that the receptor is self-compiexing into a dimer receptor 2 center dot 2. The self-complexation of the r......The synthesis and binding properties of a tetrathiafulvalene (TTF)-calix[4]pyrrole receptor 2 appended with one 3,5-dinitrobenzoate guest moiety are reported. The preliminary studies revealed that the receptor is self-compiexing into a dimer receptor 2 center dot 2. The self...

New pyrrole inhibitors of monoamine oxidase: synthesis, biological evaluation, and structural determinants of MAO-A and MAO-B selectivity.

Science.gov (United States)

La Regina, Giuseppe; Silvestri, Romano; Artico, Marino; Lavecchia, Antonio; Novellino, Ettore; Befani, Olivia; Turini, Paola; Agostinelli, Enzo

2007-03-08

A series of new pyrrole derivatives have been synthesized and evaluated for their monoamine oxidase (MAO) A and B inhibitory activity and selectivity. N-Methyl,N-(benzyl),N-(pyrrol-2-ylmethyl)amine (7) and N-(2-benzyl),N-(1-methylpyrrol-2-ylmethyl)amine (18) were the most selective MAO-B (7, SI = 0.0057) and MAO-A (18, SI = 12500) inhibitors, respectively. Docking and molecular dynamics simulations gave structural insights into the MAO-A and MAO-B selectivity. Compound 18 forms an H-bond with Gln215 through its protonated amino group into the MAO-A binding site. This H-bond is absent in the 7/MAO-A complex. In contrast, compound 7 places its phenyl ring into an aromatic cage of the MAO-B binding pocket, where it forms charge-transfer interactions. The slightly different binding pose of 18 into the MAO-B active site seems to be forced by a bulkier Tyr residue, which replaces a smaller Ile residue present in MAO-A.

Self-Aggregation in Pyrrole:  Matrix Isolation, Solid State Infrared Spectroscopy, and DFT Study

OpenAIRE

Gómez-Zavaglia, Andrea; Fausto, Rui

2004-01-01

Pyrrole (C4H5N) was embedded in low-temperature solid inert matrixes (argon, xenon; T = 9 K) and both the monomer and low-order aggregates characterized by FTIR spectroscopy. The spectroscopic studies were complemented by extensive theoretical [DFT(B3LYP)/6-311++G(d,p)] structural and vibrational studies carried out for the monomer and their self-aggregates (up to four units). The calculated spectrum for monomeric pyrrole fits well those obtained immediately after deposition (at 9 K) of dilut...

Studies of pyrrole black electrodes as possible battery positive electrodes

Energy Technology Data Exchange (ETDEWEB)

Mengoli, G.; Musiani, M.M.; Fleischmann, M.; Pletcher, D.

1984-05-01

It is shown that a polypyrrole, pyrrole black, may be formed anodically in several aqueous acids. The polypyrrole film shows a redox couple at less positive potentials than that required to form the film and the charge associated with these reduction and oxidation processes together with their stabilty to cycling varies with the anion in solution and the potential where the polypyrrole is formed; over-oxidation of the film caused by taking its potential too positive has a particularly disadvantageous affect. In the acids HBr and HI, the polypyrrole films can act as a storage medium for Br/sub 2/ or I/sub 2/ so that they may be used as a substrate for a X/sub 2//X/sup -/ electrode. Such electrodes may be charge/discharge cycled and the pyrrole/Br/sub 2/ electrode shows promise as a battery positive electrode.

Crystal structures of unsymmetrically mixed β-pyrrole substituted ...

Indian Academy of Sciences (India)

NiTPP(Ph)3(CN)5, 3 complex was synthesized and its solvated structure was examined by crystallography. ... sive interactions among the peripheral substituents.28,29 ... 1H NMR spectra of porphyrins were. 1047 ... Single crystals of MTPP(Ph)3Cl5 (M = 2H and Ni(II)) .... by ∼0.3–0.6ppm but β-pyrrole phenyls do not show.

Asymmetrically substituted calix[4]pyrrole with chiral substituents

Czech Academy of Sciences Publication Activity Database

Štěpánek, P.; Šimák, Ondřej; Nováková, Z.; Wimmer, Zdeněk; Drašar, P.

2011-01-01

Roč. 9, č. 3 (2011), s. 682-683 ISSN 1477-0520 R&D Projects: GA MŠk 2B06024 Grant - others:NATO(XE) CBP.EAP.CLG.982972 Institutional research plan: CEZ:AV0Z40550506; CEZ:AV0Z50380511 Keywords : porphyrin derivatives * anion-binding * aggregation * pyrrole * ketones Subject RIV: CC - Organic Chemistry Impact factor: 3.696, year: 2011

Metallation of N-allenylpyrroles by superbase reagents. Synthesis of new N-substituted pyrroles

International Nuclear Information System (INIS)

Tarasova, O.A.; Brandsma, L.; Verkrajsse, Kh.D.; Mal'kina, A.G.; Trofimov, B.A.

1996-01-01

Metallation of N-allenylpyrrole by BuLi-Et 2 O (THP), BuLi-t-BuOK-THP superbases and reactions of carbanions formed with different electrophilic agents have been studied. Fundamental data on mutual influence of allene group and pyrrole ring have been obtained. Alpha-proton features the highest acidity and it is the first one to be replaced by metal. In BuLi excess (more than 3-fold) in ether or in BuLi-t-BuOK-THP system a through metallation of allene group occurs. New pyrroles functionally substituted in allene chain have been prepared. 19 refs.; 3 tabs

Interesting reactivity of diketones with pyrrole under acidic condition

Indian Academy of Sciences (India)

e-mail: pkpsc@uohyd.ernet.in; pradeepta.panda@gmail.com. MS received 18 October 2010; revised 7 June 2011; accepted 13 June 2011. Abstract. The acid catalysed condensation of diketones with pyrrole did not result in the formation of expected divergent bisdipyrromethane always; instead the product depends on the ...

Structure and Oxidation of Pyrrole Adducts Formed between Aflatoxin B2a and Biological Amines.

Science.gov (United States)

Rushing, Blake R; Selim, Mustafa I

2017-06-19

Aflatoxin B 2a has been shown to bind to proteins through a dialdehyde intermediate under physiological conditions. The proposed structure of this adduct has been published showing a Schiff base interaction, but adequate verification using structural elucidation instrumental techniques has not been performed. In this work, we synthesized the aflatoxin B 2a amino acid adduct under alkaline conditions, and the formation of a new product was determined using high performance liquid chromatography-time-of-flight mass spectrometry. The resulting accurate mass was used to generate a novel proposed chemical structure of the adduct in which the dialdehyde forms a pyrrole ring with primary amines rather than the previously proposed Schiff base interaction. The pyrrole structure was confirmed using 1 H, 13 C, correlation spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond correlation NMR and tandem mass spectrometry. Reaction kinetics show that the reaction is overall second order and that the rate increases as pH increases. Additionally, this study shows for the first time that aflatoxin B 2a dialdehyde forms adducts with phosphatidylethanolamines and does so through pyrrole ring formation, which makes it the first aflatoxin-lipid adduct to be structurally identified. Furthermore, oxidation of the pyrrole adduct produced a product that was 16 m/z heavier. When the aflatoxin B 2a -lysine (ε) adduct was oxidized, it gave a product with an accurate mass, mass fragmentation pattern, and 1 H NMR spectrum that match aflatoxin B 1 -lysine, which suggest the transformation of the pyrrole ring to a pyrrolin-2-one ring. These data give new insight into the fate and chemical properties of biological adducts formed from aflatoxin B 2a as well as possible interferences with known aflatoxin B 1 exposure biomarkers.

Catalytic formal [2+2+1] synthesis of pyrroles from alkynes and diazenes via Ti(II)/Ti(IV) redox catalysis.

Science.gov (United States)

Gilbert, Zachary W; Hue, Ryan J; Tonks, Ian A

2016-01-01

Pyrroles are structurally important heterocycles. However, the synthesis of polysubstituted pyrroles is often challenging. Here, we report a multicomponent, Ti-catalysed formal [2+2+1] reaction of alkynes and diazenes for the oxidative synthesis of penta- and trisubstituted pyrroles: a nitrenoid analogue to classical Pauson-Khand-type syntheses of cyclopentenones. Given the scarcity of early transition-metal redox catalysis, preliminary mechanistic studies are presented. Initial stoichiometric and kinetic studies indicate that the mechanism of this reaction proceeds through a formally Ti(II)/Ti(IV) redox catalytic cycle, in which an azatitanacyclobutene intermediate, resulting from [2+2] alkyne + Ti imido coupling, undergoes a second alkyne insertion followed by reductive elimination to yield pyrrole and a Ti(II) species. The key component for catalytic turnover is the reoxidation of the Ti(II) species to a Ti(IV) imido via the disproportionation of an η(2)-diazene-Ti(II) complex.

Efficient assembly of polysubstituted pyrroles via a (3 + 2) cycloaddition/skeletal rearrangement/redox isomerization cascade reaction.

Science.gov (United States)

Yu, Yuanyuan; Wang, Chunyu; He, Xinze; Yao, Xiaotong; Zu, Liansuo

2014-07-03

An unprecedented cascade strategy, used in conjunction with a redox isomerization, for the synthesis of 3-allyl pyrroles is reported. In a single step, readily accessible simple starting materials are transformed into highly substituted pyrroles with high efficiency. The products obtained contain allyl substituents, which can be readily elaborated to other useful functional groups. The reaction proceeds through an unusual (3 + 2) cycloaddition/skeletal rearrangement/redox isomerization pathway.

Lipid-Lowering Effects of Ethyl 2-Phenacyl-3-aryl-1H-pyrrole- 4-carboxylates in Rodents

Directory of Open Access Journals (Sweden)

Bruce S. Burnham

2004-02-01

Full Text Available A series of substituted 2-phenacyl-3-phenyl-1H-pyrrole-4-carboxylates were prepared from substituted acetophenones in 6 steps. The final condensations between a chloroenal and an aminoketone were carried out under neutral conditions in parallel to yield the series listed below. Selected pyrrole derivatives proved to be potent hypolipidemic agents lowering serum triglyceride concentrations in CF-1 male mice after 14 days of I.P. administration. One agent orally lowered serum cholesterol in Sprague-Dawley male rats at 2mg/kg/day after 14 days. The agents demonstrated a lowering of mouse serum LDL- cholesterol levels and selected compounds showed an elevation of serum HDL-cholesterol levels. The cholesterol concentrations in the liver were raised while the cholesterol and triglyceride contents of the aorta were significantly lowered by the selected trisubstituted pyrrole.

Electrochromic properties of multicolored novel polymer synthesized via combination of benzotriazole and N-functionalized 2,5-di(2-thienyl)-1H-pyrrole units

International Nuclear Information System (INIS)

Rende, Eda; Kilic, Cihan E.; Udum, Yasemin Arslan; Toffoli, Daniele; Toppare, Levent

2014-01-01

Synthesis of new conducting polymers is desired since their electrochemical and optical properties enable them to be used as active layers in many device applications. Benzotriazole and N-functionalized 2,5-di(2-thienyl)-1H-pyrrole (SNS Series) containing polymers showed very promising results as electrochromic materials. In order to observe the effect of the combination of these two units, three new monomers; 2-(6-(2,5-bis(5-methylthiophen-2-yl)-1H-pyrrol-1-yl)hexyl)-4,7-di (thiophen-2-yl)-2H benzo[d][1,2,3]triazole (M1), 2-(6-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)hexyl)-4,7-di(thiophen-2-yl) -2H-benzo[d][1,2,3]triazole (M2) and 2-(6-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)hexyl)-4,7-bis (5-methylthiophen-2-yl)-2H-benzo[d][1,2,3]triazole (M3) were synthesized. To better characterize the electronic and spectroscopic properties of the monomers, density functional theory (DFT) and its time-dependent generalization (TD-DFT) were used to calculate their vertical ionization potentials, vertical electron affinity and to simulate and interpret their infrared and UV-vis spectra. The monomers were electrochemically polymerized and the resultant polymers were characterized with cyclic voltammetry and UV-vis-NIR spectroscopy techniques. An electrochromic device was constructed with electrochemical polymer of M2. The device switched between red and blue colors and showed exceptional optical memory

A C{sub 2}-symmetric ratiometric fluorescence and colorimetric anion sensor based on pyrrole derivative

Energy Technology Data Exchange (ETDEWEB)

Liu Ge [Department of Chemistry, Chifeng University, Chifeng 024000 (China); Shao Jie, E-mail: njshao@live.c [Department of Chemistry and Materials Science, Nanjing Forestry University, Nanjing 210037 (China)

2011-07-15

A C{sub 2}-symmetric fluorescence and colorimetric anion sensor (1) based on pyrrole derivative was designed and synthesized according to binding site-signaling subunit approach. The compound 1 was easily prepared by reaction of pyrrole-2,5-dicarboxaldehyde with 4-nitrophenylhydrazine in ethanol (yield=78%). In DMSO, the sensor 1 exhibited a visible color change from red to brown upon exposure to anions such as AcO{sup -} and F{sup -}; however, no obvious color changes were observed when the other tested anions (e. g. H{sub 2}PO{sub 4}{sup -}, Cl{sup -}, Br{sup -} and I{sup -}) were added. There was a significant redshift ({Delta}{lambda}{sub max}=160 nm) in UV-vis spectrum during UV-vis spectral titrations. In particular, the sensor 1 showed ratiometric fluorescence responses to anions. - Highlights: {yields} C{sub 2}-symmetric fluorescence and colorimetric anion sensor based on pyrrole derivative was designed and synthesized according to binding site-signaling subunit approach. {yields} The sensor was easily prepared by reaction of pyrrole-2,5-dicarboxaldehyde with 4-nitrophenylhydrazine in ethanol (yield=78%). {yields} In DMSO, the sensor exhibited a visible color change from red to brown upon exposure to anions such as AcO{sup -} and F{sup -}, however, no obvious color changes were observed when the other anions tested (e. g. H{sub 2}PO{sub 4}{sup -}, Cl{sup -}, Br{sup -} and I{sup -}) were added. {yields} The sensor showed ratiometric fluorescence responses to anions.

Development of chitosan-coated gold nanoflowers as SERS-active probes

Science.gov (United States)

Xu, Dan; Gu, Jiangjiang; Wang, Weina; Yu, Xuehai; Xi, Kai; Jia, Xudong

2010-09-01

Surface-enhanced Raman scattering (SERS) has been intensely researched for many years as a potential technique for highly sensitive detection. This work, through the reduction of HAuCl4 with pyrrole in aqueous solutions, investigated a facile one-pot synthesis of flower-like Au nanoparticles with rough surfaces. The formation process of the Au nanoflowers (AuNFs) was carefully studied, and a spontaneous assembly mechanism was proposed based on the time-course experimental results. The key synthesis strategy was to use pyrrole as a weak particle stabilizing and reducing agent to confine crystal growth in the limited ligand protection region. The nanometer-scale surface roughness of AuNFs provided several hot spots on a single particle, which significantly increased SERS enhancement. Good biocompatible stable Raman-active probes were synthesized by coating AuNFs with chitosan. The conservation of the SERS effects in living cells suggested that the chitosan-capped AuNFs could be suitable for highly sensitive detection and have potential for targeting of tumors in vivo.

Electrical and dielectric investigation of intercalated polypyrrole montmorillonite nanocomposite prepared by spontaneous polymerization of pyrrole into Fe(III)-montmorillonite

Energy Technology Data Exchange (ETDEWEB)

Zidi, Rabii, E-mail: rabiizidi@gmail.com [Physical Chemistry Laboratory for Mineral Materials and their Applications, National Center for Research in Materials Sciences (CNRSM), B.P.73, 8020 Soliman (Tunisia); Bekri-Abbes, Imene; Sdiri, Nasr [Physical Chemistry Laboratory for Mineral Materials and their Applications, National Center for Research in Materials Sciences (CNRSM), B.P.73, 8020 Soliman (Tunisia); Vimalanandan, Ashokanand; Rohwerder, Michael [Max-Planck-Institut für Eisenforschung GmbH, Düsseldorf (Germany); Srasra, Ezzeddine [Physical Chemistry Laboratory for Mineral Materials and their Applications, National Center for Research in Materials Sciences (CNRSM), B.P.73, 8020 Soliman (Tunisia)

2016-10-15

Highlights: • We have prepared and characterized a Fe-MMT/PPy nanocomposites. • Investigate electrical conductivity and dielectric properties of the nanocomposite. • Investigate the temperature and frequency dependencies of alternating current conductivity of nanocomposites. - Abstract: Pyrrole was introduced into Fe(III)-exchanged montmorillonite to spontaneously polymerize within the interlayer resulting in the formation of intercalated polypyrrole-montmorillonite nanocomposite. The molar proportion of pyrrole to interlayer Fe{sup 3+} (R) has been varied from 0.5 to 5. The nanocomposite has been characterized by X-ray diffraction, Scanning Electronic Microscope, FTIR spectroscopy and impedance spectroscopy. It has been shown that intercalated polypyrrole montmorillonite nanocomposite was obtained. The results showed that the dc conductivity and dielectric properties of polypyrrole depend on R. The alternating current (ac) conductivity of the polymer obeys the power law, i.e., σ{sub ac}(ω) = Aω{sup s}. The alternating conductivity of nanocomposite was controlled by the correlated barrier hopping model. The activation energy for alternating current mechanism decreases with increasing frequency which confirms the hopping conduction to the dominant mechanism as compared with the dc activation energy. The dielectric relaxation mechanism was explained on the basis of complex dielectric modulus.

Sulfur-containing constituents and one 1H-pyrrole-2-carboxylic acid derivative from pineapple [Ananas comosus (L.) Merr.] fruit.

Science.gov (United States)

Zheng, Zong-Ping; Ma, Jinyu; Cheng, Ka-Wing; Chao, Jianfei; Zhu, Qin; Chang, Raymond Chuen-Chung; Zhao, Ming; Lin, Zhi-Xiu; Wang, Mingfu

2010-12-01

Two sulfur-containing compounds, (S)-2-amino-5-((R)-1-carboxy-2-((E)-3-(4-hydroxy-3-methoxyphenyl)allylthio)ethyl-amino)-5-oxopentanoic acid (1) and (S)-2-amino-5-((R)-1-(carboxymethylamino)-3-((E)-3-(4-hydroxyphenyl)allylthio)-1-oxopropan-2-ylamino)-5-oxopentanoic acid (2), and one 1H-pyrrole-2-carboxylic acid derivative, 6-(3-(1H-pyrrole-2-carbonyloxy)-2-hydroxypropoxy)-3,4,5-trihydroxy-tetrahydro-2H-pyran-2-carboxylic acid (3), together with eighteen known phenolic compounds, were isolated from the fruits of pineapple. Their structures were elucidated by a combination of spectroscopic analyses. Some of these compounds showed inhibitory activities against tyrosinase. The half maximal inhibitory concentration values of compounds 1, 4, 5, 6, 7 are lower than 1 mM. These compounds may contribute to the well-known anti-browning effect of pineapple juice and be potential skin whitening agents in cosmetic applications. Copyright © 2010 Elsevier Ltd. All rights reserved.

Ultrasound-assisted green synthesis of pyrroles and pyridazines in water via three-component condensation reactions of arylglyoxals

Directory of Open Access Journals (Sweden)

Bagher Eftekhari-Sis

2013-04-01

Full Text Available A green and efficient method for the preparation of 5-aryl-4-hydroxy-2-methyl-1H-pyrrole-3-carboxylic acid esters and 6-aryl-3-methylpyridazine-4-carboxylic acid esters via three-component reaction of arylglyoxal hydrates with β-dicarbonyl compounds in the presence of ammonium acetate and hydrazine hydrate using water as solvent under ultrasonic irradiation was reported. The reactions proceeded rapidly and afforded the corresponding pyrroles and pyridazines in good to high yields in very short reaction time.

A role of nanotube dangling pyrrole and oxygen functions in the electrochemical synthesis of polypyrrole/MWCNTs hybrid materials

International Nuclear Information System (INIS)

Krukiewicz, Katarzyna; Herman, Artur P.; Turczyn, Roman; Szymańska, Katarzyna; Koziol, Krzysztof K.K.; Boncel, Sławomir; Zak, Jerzy K.

2014-01-01

Highlights: • The effect of MWCNT functionalization on properties of PPy composites was explained. • The behavior of pristine, pyrrole-modified and oxidized MWCNT was explained. • Functionalization of MWCNT improved their dispersibility and processability. • Different mechanisms of (f-)MWCNT incorporation into PPy composites were explained. • Orientation of growing PPy chains was tailored through the addition of (f-)MWCNT. - Abstract: The effect of the functionalization of multi-walled carbon nanotubes (MWCNTs) on the process of electrochemical co-deposition of MWCNTs and polypyrrole (PPy), as well as the morphology of obtained composites have been demonstrated. As the nanotube components of the hybrids, three types of MWCNT were used, namely c-CVD derived (pristine) MWCNTs, their oxidized counterparts MWCNT-Ox and pyrrole-modified MWCNT-Py. The stability of pristine and functionalized MWCNTs (f-MWCNT) dispersions in tetrahydrofuran and water was studied together with the description of the process of formation PPy/(f-)MWCNT hybrid materials via electrochemical co-deposition. The structural and morphological properties of the hybrids were characterized by Raman spectroscopy, scanning electron microscopy and atomic force microscopy revealing substantial differences among hybrid materials in their surface morphology and the influence of MWCNT functionalization on the orientation of growing PPy chains

A role of nanotube dangling pyrrole and oxygen functions in the electrochemical synthesis of polypyrrole/MWCNTs hybrid materials

Energy Technology Data Exchange (ETDEWEB)

Krukiewicz, Katarzyna, E-mail: katarzyna.krukiewicz@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland); Herman, Artur P., E-mail: artur.herman@polsl.pl [Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology, Silesian University of Technology, Krzywoustego 4, Gliwice 44-100 (Poland); Turczyn, Roman, E-mail: roman.turczyn@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland); Szymańska, Katarzyna, E-mail: katarzyna.szymanska@polsl.pl [Department of Chemical and Process Engineering, Silesian University of Technology, Strzody 7, 44-100 Gliwice (Poland); Koziol, Krzysztof K.K., E-mail: kk292@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Boncel, Sławomir, E-mail: slawomir.boncel@polsl.pl [Department of Organic Chemistry, Bioorganic Chemistry and Biotechnology, Silesian University of Technology, Krzywoustego 4, Gliwice 44-100 (Poland); Zak, Jerzy K., E-mail: jerzy.zak@polsl.pl [Department of Physical Chemistry and Technology of Polymers, Silesian University of Technology, Strzody 9, 44-100 Gliwice (Poland)

2014-10-30

Highlights: • The effect of MWCNT functionalization on properties of PPy composites was explained. • The behavior of pristine, pyrrole-modified and oxidized MWCNT was explained. • Functionalization of MWCNT improved their dispersibility and processability. • Different mechanisms of (f-)MWCNT incorporation into PPy composites were explained. • Orientation of growing PPy chains was tailored through the addition of (f-)MWCNT. - Abstract: The effect of the functionalization of multi-walled carbon nanotubes (MWCNTs) on the process of electrochemical co-deposition of MWCNTs and polypyrrole (PPy), as well as the morphology of obtained composites have been demonstrated. As the nanotube components of the hybrids, three types of MWCNT were used, namely c-CVD derived (pristine) MWCNTs, their oxidized counterparts MWCNT-Ox and pyrrole-modified MWCNT-Py. The stability of pristine and functionalized MWCNTs (f-MWCNT) dispersions in tetrahydrofuran and water was studied together with the description of the process of formation PPy/(f-)MWCNT hybrid materials via electrochemical co-deposition. The structural and morphological properties of the hybrids were characterized by Raman spectroscopy, scanning electron microscopy and atomic force microscopy revealing substantial differences among hybrid materials in their surface morphology and the influence of MWCNT functionalization on the orientation of growing PPy chains.

Post Hartree–Fock and DFT Studies on Pyrrole···Nitrogen and Pyrrole···Carbon Monoxide Molecules

Directory of Open Access Journals (Sweden)

P. Kolandaivel

2002-07-01

Full Text Available Abstract: The hydrogen bonded and van der Waals isomers of pyrrole···nitrogen and pyrrole···carbon monoxide have been studied using ab initio and density functional theory methods. Complex geometries and total energies of the isomers have been determined at HF, MP2, B3LYP and B3PW91 levels of theory employing 6-31G* basis set. For pyrrole···nitrogen complex, only two isomers have stable structure and the more stable one is found to be the hydrogen bonded isomer. Among the five isomers of pyrrole···carbon monoxide complex, the hydrogen bonded isomer is found to be the most stable form. The interaction energy for all these isomers have been calculated after eliminating the basis set superposition errors by using the full counterpoise correction method. Chemical hardness, chemical potential have been calculated and are used to study the stability of the molecules.

One-pot Synthesis of Substituted Pyrroles with N,N,N',N'

African Journals Online (AJOL)

In this research, N,N,N'N'-tetrachlorobenzene-1,3-disulphonamide as novel catalytic reagent and N,N'-diiodo-N,N'-1,2-ethanediylbis(p-toluenesulphonamide) as new catalyst were used for the synthesis of N-substituted pyrroles in good to excellent yields under mild conditions. These reusable reagents were compared with ...

Graphene/Poly(aniline-co-pyrrole) Nanocomposite: Potential Candidate for Supercapacitor and Microwave Absorbing Applications.

Science.gov (United States)

Sahoo, Sumanta; Bhattacharya, Pallab; Dhibar, Saptarshi; Hatui, Goutam; Das, Tanya; Das, Chapal Kumar

2015-09-01

A simple and cost-effective in-situ chemical route to prepare the nanocomposites based on graphene and Poly(aniline-co-pyrrole) [PPP] has been proposed. Introduction of graphene changes the morphology of copolymer from spherical to fiber like. Graphene/Poly(aniline-co-pyrrole) [GPPP] nanocomposite achieved highest specific capacitance of 351 F/g and energy density of 124.8 Wh/Kg at 10 mV/s scan rate. The composite also obtained moderate specific capacitance retention of 66% after 500 cycles, which establish its potentiality as supercapacitor electrode materials. The composite also exhibited high electrical conductivity and superior microwave absorbing properties (maximum reflection loss is -29.97 dB). The absorption range corresponding to ≥ 90% absorption (or -10 dB) is 2.72 GHz which is excellent for the microwave absorbing applications.

Direct detection of pyridine formation by the reaction of CH (CD) with pyrrole: a ring expansion reaction

Energy Technology Data Exchange (ETDEWEB)

Soorkia, Satchin; Taatjes, Craig A.; Osborn, David L.; Selby, Talitha M.; Trevitt, Adam J.; Wilson, Kevin R.; Leone, Stephen R.

2010-03-16

The reaction of the ground state methylidyne radical CH (X2Pi) with pyrrole (C4H5N) has been studied in a slow flow tube reactor using Multiplexed Photoionization Mass Spectrometry coupled to quasi-continuous tunable VUV synchrotron radiation at room temperature (295 K) and 90 oC (363 K), at 4 Torr (533 Pa). Laser photolysis of bromoform (CHBr3) at 248 nm (KrF excimer laser) is used to produce CH radicals that are free to react with pyrrole molecules in the gaseous mixture. A signal at m/z = 79 (C5H5N) is identified as the product of the reaction and resolved from 79Br atoms, and the result is consistent with CH addition to pyrrole followed by Helimination. The Photoionization Efficiency curve unambiguously identifies m/z = 79 as pyridine. With deuterated methylidyne radicals (CD), the product mass peak is shifted by +1 mass unit, consistent with the formation of C5H4DN and identified as deuterated pyridine (dpyridine). Within detection limits, there is no evidence that the addition intermediate complex undergoes hydrogen scrambling. The results are consistent with a reaction mechanism that proceeds via the direct CH (CD) cycloaddition or insertion into the five-member pyrrole ring, giving rise to ring expansion, followed by H atom elimination from the nitrogen atom in the intermediate to form the resonance stabilized pyridine (d-pyridine) molecule. Implications to interstellar chemistry and planetary atmospheres, in particular Titan, as well as in gas-phase combustion processes, are discussed.

Synthesis of novel synthetic intermediates from the reaction of benzimidazole and triazole carbenes with ketenimines and their application in the construction of spiro-pyrroles.

Science.gov (United States)

Mo, Jun-Ming; Ma, Yang-Guang; Cheng, Ying

2009-12-07

2-(2-Alkoxycarbonyl-1-arylamino-1-propenyl)benzimidazolium and 5-(2-alkoxycarbonyl-1-arylamino-1-propenyl)triazolium salts were synthesized in good yields from the reaction of benzimidazole and triazole carbenes with ketenimines. Upon treatment with a base, both salts were converted into novel 1,3-dipoles which underwent [3+2] cycloaddition reactions with electron-deficient alkynes and allenes to produce benzimidazole-spiro-pyrroles or triazole-spiro-pyrroles. This work provides novel synthons for the construction of multifunctional spiro-pyrrole derivatives that are not easy accessible by other synthetic methods and are potentially amenable to further transformations.

Ethyl 5-cyano-4-[2-(2,4-dichlorophenoxyacetamido]-1-phenyl-1H-pyrrole-3-carboxylate

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Jing Xu

2009-08-01

Full Text Available In the title compound, C22H17Cl2N3O4, the pyrrole ring and the 2,4-dichlorophenyl group form a dihedral angle of 8.14 (13°; the phenyl ring is twisted with respect to the pyrrole ring, forming a dihedral angle of 60.77 (14°. The C=O bond length is 1.213 (3 Å, indicating that the molecule is in the keto form, associated with a –CONH– group, and the amide group adopts the usual trans conformation. The molecule is stabilized by an intramolecular N—H...O hydrogen-bonding interaction. In the crystal, the stacked molecules exhibit intermolecular C—H...O and C—H...N hydrogen-bonding interactions.

The preparation of polypyrrole surfaces in the presence of mesoporous silica nanoparticles and their biomedical applications

Science.gov (United States)

Cho, Youngnam; Ben Borgens, Richard

2010-05-01

The deposition of carboxylic acid-terminated conducting polymer into two- or three-dimensional structures made up of colloidal particles has been successfully completed. This was accomplished using electrochemical deposition of ordered arrays of mesoporous silica nanoparticles (MSNs) as a template. Subsequent removal of the template yielded a porous polypyrrole surface. The co-polymerization of pyrrole with carboxylic acid-terminated pyrrole derivatives overcame the limitations of a lack of reactive functional groups—by facilitating the direct coupling of the film with biomolecules or drugs on the surface. Such Ppy films were characterized by several techniques: (1) scanning electron microscope (SEM) to evaluate surface topography, (2) x-ray photoelectron spectroscopy (XPS) to assess the chemical composition of the films, (3) four-point probe to measure the conductivity, and cyclic voltammogram to observe surface electroactivity. To assay the biological effectiveness of this preparation, we used phase-contrast light microscopy to compare neurite outgrowth from PC 12 cells grown on Ppy films in the presence and absence of electrical stimulation. These electrically functional, biocompatible composites show promise as novel neural implants that would deliver specific biologically active molecules in a highly localized manner to damaged or otherwise vulnerable cells such as found in the nervous system.

The preparation of polypyrrole surfaces in the presence of mesoporous silica nanoparticles and their biomedical applications

International Nuclear Information System (INIS)

Cho, Youngnam; Borgens, Richard Ben

2010-01-01

The deposition of carboxylic acid-terminated conducting polymer into two- or three-dimensional structures made up of colloidal particles has been successfully completed. This was accomplished using electrochemical deposition of ordered arrays of mesoporous silica nanoparticles (MSNs) as a template. Subsequent removal of the template yielded a porous polypyrrole surface. The co-polymerization of pyrrole with carboxylic acid-terminated pyrrole derivatives overcame the limitations of a lack of reactive functional groups-by facilitating the direct coupling of the film with biomolecules or drugs on the surface. Such Ppy films were characterized by several techniques: (1) scanning electron microscope (SEM) to evaluate surface topography, (2) x-ray photoelectron spectroscopy (XPS) to assess the chemical composition of the films, (3) four-point probe to measure the conductivity, and cyclic voltammogram to observe surface electroactivity. To assay the biological effectiveness of this preparation, we used phase-contrast light microscopy to compare neurite outgrowth from PC 12 cells grown on Ppy films in the presence and absence of electrical stimulation. These electrically functional, biocompatible composites show promise as novel neural implants that would deliver specific biologically active molecules in a highly localized manner to damaged or otherwise vulnerable cells such as found in the nervous system.

Characterization of electro-conductive fabrics prepared by in situ chemical and electrochemical polymerization of pyrrole onto polyester fabric

Energy Technology Data Exchange (ETDEWEB)

Maiti, Syamal; Das, Dipayan; Sen, Kushal, E-mail: kushal@textile.iitd.ernet.in

2014-09-15

Highlights: • Surface resistivity of the fabrics decreased rapidly with an increase in add-on. • Add-on and resistivity were not correlated below a resistivity value of about 200 Ω. • Higher add-on but lower surface roughness resulted in lower surface resistivity. • The voltage–current and voltage–temperature behaviours were found to be non-linear. • Electro-conductive fabric exhibited 98% electromagnetic shielding efficiency. - Abstract: This paper reports a study on electro-conductive fabrics prepared by a combined in situ chemical and electrochemical polymerization of pyrrole. Specific observations are made to establish the roles of add-on and surface roughness on the surface resistivity of the electro-conductive fabrics. The performance characteristics of the fabrics are reported in terms of electrical conductivity, voltage–current and voltage–temperature characteristics and electromagnetic interference (EMI) shielding capability. The surface resistivity of the fabric was found to be as low as 11.79 Ω. The voltage–current profile of the fabric is observed to be non-ohmic as well as the voltage–temperature curve is found to be exponential. The EMI shielding efficiency of the fabric was found to be about 98%.

Characterization of electro-conductive fabrics prepared by in situ chemical and electrochemical polymerization of pyrrole onto polyester fabric

International Nuclear Information System (INIS)

Maiti, Syamal; Das, Dipayan; Sen, Kushal

2014-01-01

Highlights: • Surface resistivity of the fabrics decreased rapidly with an increase in add-on. • Add-on and resistivity were not correlated below a resistivity value of about 200 Ω. • Higher add-on but lower surface roughness resulted in lower surface resistivity. • The voltage–current and voltage–temperature behaviours were found to be non-linear. • Electro-conductive fabric exhibited 98% electromagnetic shielding efficiency. - Abstract: This paper reports a study on electro-conductive fabrics prepared by a combined in situ chemical and electrochemical polymerization of pyrrole. Specific observations are made to establish the roles of add-on and surface roughness on the surface resistivity of the electro-conductive fabrics. The performance characteristics of the fabrics are reported in terms of electrical conductivity, voltage–current and voltage–temperature characteristics and electromagnetic interference (EMI) shielding capability. The surface resistivity of the fabric was found to be as low as 11.79 Ω. The voltage–current profile of the fabric is observed to be non-ohmic as well as the voltage–temperature curve is found to be exponential. The EMI shielding efficiency of the fabric was found to be about 98%

Formation process of silver-polypyrrole coaxial nanocables synthesized by redox reaction between AgNO3 and pyrrole in the presence of poly(vinylpyrrolidone).

Science.gov (United States)

Chen, Aihua; Kamata, Kaori; Nakagawa, Masaru; Iyoda, Tomokazu; Haiqiao Wang, Haiqiao; Li, Xiaoyu

2005-10-06

We have recently demonstrated a one-step process to fabricate silver-polypyrrole (PPy) coaxial nanocables (Chen, A.; Wang, H.; Li, X. Chem. Commun. 2005, 14, 1863). The formation process of silver-PPy coaxial nanocables is discussed in this article. It was found from the results of TEM and SEM images that large numbers of silver atoms were formed when AgNO3 was added to a pyrrole solution. Then silver atoms transform to silver-PPy nanosheets with regular morphology, which will connect together to be more stable. Silver-PPy nanocables will be able to grow at the expense of the silver-PPy nanosheets. Poly(vinylpyrrolidone) (PVP) plays crucial roles in this process: as a capping agent to form silver nanowires, and as a dispersant of pyrrole monomers, which can influence the site at which pyrrole monomer exists. On the basis of experimental analysis, the possible mechanism was proposed. Because of the effect of PVP, silver ions and pyrrole monomers are apt to be adsorbed at the [111] and [100] facets of silver nanosheets, respectively. Obvious polymerization will take place on the boundary of the [111] and [100] facets. The PPy layer stays stable on the [100] facets. Meanwhile, newly formed silver atoms and silver nanosheets will further ripen and grow on the [111] facets. In a word, the morphology of final products and the formation process are determined by the reaction site between AgNO3 and the pyrrole monomer, which is influenced by PVP.

Synthesis of 2-[4-(10H-Substituted Phenothiazine-3-yl-6-Pyrimidin-2-Phenylthiol/ol/amine/thiol] Pyrroles

Directory of Open Access Journals (Sweden)

Meghasham Narule

2007-01-01

Full Text Available 2-[4-Hydroxy benz-1(propene-1-one]Pyrrole II on treatment with phenyl thiourea, guanidine carbonate, urea and thiourea in alcoholic KOH yielded compounds III, IV, V, VI which on treatment with different aryl anilines gave compounds VII, VIII, IX, X which under goes cyclisation with sulphur and iodine to give 2-[4-(10H-substituted phenothiazine-3-yl-6-pyrimidin-2-phenylthiol/-ol/-amine/-thiol] pyrrole XI(a-j, XII(a-j, XIII(a-j and XIV(a-j respectively. The structural products were characterized by elemental analysis and spectral data.

Biosynthesis, asymmetric synthesis, and pharmacology, including cellular targets, of the pyrrole-2-aminoimidazole marine alkaloids

Digital Repository Service at National Institute of Oceanography (India)

Al-Mourabit, A.; Zancanella, M.A.; Tilvi, S.; Romo, D.

The pyrrole-2-aminoimidazole (P-2-AI) alkaloids are a growing family of marine alkaloids, now numbering well over 150 members, with high topographical and biological information content. Their intriguing structural complexity, rich and compact...

High content of pyridinic- and pyrrolic-nitrogen-modified carbon nanotubes derived from blood biomass for the electrocatalysis of oxygen reduction reaction in alkaline medium

International Nuclear Information System (INIS)

Zheng, Jie; Guo, Chaozhong; Chen, Chunyan; Fan, Mingzhi; Gong, Jianping; Zhang, Yanfang; Zhao, Tianxin; Sun, Yuelin; Xu, Xiaofan; Li, Mengmeng; Wang, Ran; Luo, Zhongli; Chen, Changguo

2015-01-01

Graphical abstract: Display Omitted -- Highlights: •An ORR electrocatalyst was fabricated from blood biomass and carbon nanotube. •The N-CNT catalyst exhibits good ORR activity, methanol resistance and stability. •The pyrolysis process produces high contents of pyridinic and pyrrolic N species. •The pyridinic-N group may play more important role in the active sites for ORR. -- Abstract: Here we present a facile synthetic route to design nitrogen-doped nanostructured carbon-based electrocatalyst for oxygen reduction reaction (ORR) by the copyrolysis of blood biomass from pig and carbon nanotubes (CNTs) at high temperatures. The nitrogen-doped CNTs obtained at 800 °C not only results in excellent ORR activity with four-electron transfer selectivity in alkaline medium, but also exhibits superior methanol-tolerant property and long-term stability. It is confirmed that high-temperature pyrolysis processes can facilitate to produce higher contents of pyridinic- and pyrrolic-N binding groups in electrocatalysts, contributing to the enhancement of ORR performance in terms of onset potential, half-wave potential, and limited current density. We also propose that the planar-N configuration may be the active site that is responsible for the improved ORR electrocatalytic performance. The straight-forward and cheap synthesis of the active and stable electrocatalyst makes it a promising candidate for electrochemical power sources such as fuel cells or metal-air batteries

Synthesis and characterization of N-t-BOC protected pyrrole-sulfur oligomers and polymers

NARCIS (Netherlands)

Groenendaal, L.; Pieterse, K.; Vekemans, J.A.J.M.; Meijer, E.W.

1997-01-01

The synthesis and characterization of a new class of pyrrole-sulfur compounds is described. These compounds are designed to be precursors for an organic analogue of poly(sulfur nitride). Poly(N-t-BOC-2.5-pyrrolyl sulfide) was prepared from N-t-BOC-2,5-dibromopyrrole by first lithiating this compound

Applicability of new spin trap agent, 2-diphenylphosphinoyl-2-methyl-3,4-dihydro-2H-pyrrole N-oxide, in biological system

International Nuclear Information System (INIS)

Karakawa, Tomohiro; Sato, Keizo; Muramoto, Yosuke; Mitani, Yoshihiro; Kitamado, Masataka; Iwanaga, Tatsuya; Nabeshima, Tetsuji; Maruyama, Kumiko; Nakagawa, Kazuko; Ishida, Kazuhiko; Sasamoto, Kazumi

2008-01-01

Electron spin resonance using spin-trapping is a useful technique for detecting direct reactive oxygen species, such as superoxide (O 2 .- ). However, the widely used spin trap 2,2-dimethyl-3,4-dihydro-2H-pyrrole N-oxide (DMPO) has several fundamental limitations in terms of half-life and stability. Recently, the new spin trap 2-diphenylphosphinoyl-2-methyl-3,4-dihydro-2H-pyrrole N-oxide (DPhPMPO) was developed by us. We evaluated the biological applicability of DPhPMPO to analyze O 2 .- in both cell-free and cellular systems. DPhPMPO had a larger rate constant for O 2 .- and formed more stable spin adducts for O 2 .- than DMPO in the xanthine/xanthine oxidase (X/XO) system. In the phorbol myristate acetate-activated neutrophil system, the detection potential of DPhPMPO for O 2 .- was significantly higher than that of DMPO (k DMPO = 13.95 M -1 s -1 , k DPhPMPO = 42.4 M -1 s -1 ). These results indicated that DPhPMPO is a potentially good candidate for trapping O 2 .- in a biological system

Five gene products are required for assembly of the central pyrrole moiety of coumermycin A1

Czech Academy of Sciences Publication Activity Database

Novotná, J.; Gust, B.; Kulik, A.; Spížek, Jaroslav; Heide, L.

2013-01-01

Roč. 40, č. 8 (2013), s. 915-925 ISSN 1367-5435 Institutional support: RVO:61388971 Keywords : Streptomyces * Coumermycin * Pyrrole Subject RIV: EE - Microbiology, Virology Impact factor: 2.505, year: 2013

Interaction of cesium ions with calix[2]furan[4]pyrrole and its fluoride complex

Czech Academy of Sciences Publication Activity Database

Kříž, Jaroslav; Dybal, Jiří; Makrlík, E.; Kohnke, F. H.

2012-01-01

Roč. 541, 10 July (2012), s. 27-31 ISSN 0009-2614 Institutional research plan: CEZ:AV0Z40500505 Institutional support: RVO:61389013 Keywords : calix[2]furan[4]pyrrole * Cs complex * NMR Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.145, year: 2012

SPECTROSCOPIC STUDY OF EFFECTS OF TETRAALKYLAMMONIUM CATIONS ON F--SENSING PROPERTIES OF CALIX[4]PYRROLE BORADIAZAINDACENE DYE

Directory of Open Access Journals (Sweden)

Yongjun Lv

Full Text Available A novel meso-tetracyclohexylcalix[4]pyrrole-based boradiazaindacene dye 3 was synthesized and characterized. F--binding properties of the dye in the presence of tetrabutylammonium (TBA+, tetraethylammonium (TEA+, and tetramethylammonium (TMA+ counter ions were investigated by UV-Vis, fluorescence, and NMR spectroscopies. Dye 3 displayed various degrees of absorption red shift, fluorescence quenching, and downfield shifts of NH signals for the three fluoride salts. The association constants of these salts mainly depend on cation size effects and ion-pairing effects and were in the order KTMA+ > KTEA+ > KTBA+. Thus, we speculate that both F- and tetraalkylammonium cations are concomitantly located above and below a bowl-shaped calix[4]pyrrole cup in an ion-paired complex, respectively.

Design and modelling of enzyme/poly-pyrrole modified electrodes for bio-catalyzed electro-synthesis processes

International Nuclear Information System (INIS)

Gros, Pierre

1996-01-01

This research thesis reports a study which aims at developing, analyzing and integrating an electrode-enzyme interface within an electro-enzymatic reactor to develop electrochemical biosensors. The adopted method comprises a confinement of the enzyme at the electrode surface by means of an electro-formed poly-pyrrole film. The author reports an experimental and theoretical study of the coupling between electrochemical reaction, enzymatic reaction and matter transfer in the polymer in order to better understand the operation of so-modified electrodes. Different parameters have an influence on the reaction rate. A numerical model (validated by experiments) allows the identification of the reaction limiting stages. A new elaboration protocol allows the polymer permeability to be increased. The interface is first applied to the reduction of the NAD coenzyme, and the process is also applied to the production of gluconic acid [fr

Influencing the electronic interaction in diferrocenyl-1-phenyl-1H-pyrroles.

Science.gov (United States)

Hildebrandt, Alexander; Lang, Heinrich

2011-11-28

Functionalised diferrocenyl-1-phenyl-1H-pyrroles were synthesised using Negishi C,C cross-coupling reactions. The influence of different substituents at the phenyl moiety on the electronic interaction was studied using electrochemistry (cyclic and square-wave voltammetry) and spectro-electrochemistry (in situ UV/Vis-NIR spectroscopy). The ferrocenyl moieties gave rise to two sequential, reversible redox processes in each of the diferrocenyl-1-phenyl-1H-pyrroles. The observed ΔE(1/2) values (ΔE(1/2) = difference between first and second oxidation) range between 420 and 480 mV. A linear relationship between the Hammett constants σ of the substituents and the separation of the redox potentials exists. The NIR measurements confirm electronic communication between the iron centers as intervalence charge transfer (IVCT) absorptions were observed in the corresponding mixed-valent monocationic species. All compounds were classified as class II systems according to Robin and Day (M. B. Robin and P. Day, Adv. Inorg. Chem., 1967, 10, 247-423). The oscillator strength of the charge transfer transition highly depends on the electron donating or electron withdrawing character of the phenyl substituents. This enables direct tuning of the intermetallic communication by simple modification of the molecule's functional group. Hence, this series of molecules may be regarded as model compounds for single molecule transistors.

Copper-promoted oxidative coupling of enamides and alkynes for the synthesis of substituted pyrroles.

Science.gov (United States)

Zhao, Mi-Na; Ren, Zhi-Hui; Wang, Yao-Yu; Guan, Zheng-Hui

2014-02-10

An efficient copper-promoted oxidative coupling of enamides with alkynes has been developed for the synthesis of substituted pyrroles. The reaction proceeded through C-H and N-H bond functionalization of enamides under mild conditions. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Novel composite materials synthesized by the high-temperature interaction of pyrrole with layered oxide matrices

Science.gov (United States)

Pavel, Alexandru Cezar

The initial goal of the research presented herein was to develop the very first synthetic metal---high-temperature superconductor ceramic composite material, in the specific form of a polypyrrole---Bi2Sr2CaCu 2O8+delta nanocomposite. In the course of scientific investigation, this scope was broadened to encompass structurally and compositionally similar layered bismuthates and simpler layered oxides. The latter substrates were prepared through novel experimental procedures that enhanced the chance of yielding nanostructured morphologies. The designed novel synthesis approaches yielded a harvest of interesting results that may be further developed upon their dissemination in the scientific community. High-temperature interaction of pyrrole with molybdenum trioxide substrates with different crystalline phases and morphologies led to the formation of the first members of a new class of heterogeneous microcomposites characterized by incomplete occupancy by the metal oxide core of the volume encapsulated by the rigid, amorphous permeable polymeric membrane that reproduces the volume of the initial grain of precursor substrate. The method may be applied for various heterogeneous catalyst substrates for the precise determination of the catalytically active crystallographic planes. In a different project, room-temperature, templateless impregnation of molybdenum trioxide substrates with different crystalline phases and morphologies by a large excess of silver (I) cations led to the formation of 1-D nanostructured novel Ag-Mo-O ternary phase in what may be the simplest experimental procedure available to date that has yielded a 1-D nanostructure, regardless the nature of the constituent material. Interaction of this novel ternary phase with pyrrole vapors at high reaction temperatures led to heterogeneous nanostructured composites that exhibited a silver nanorod core. Nanoscrolls of vanadium pentoxide xerogel were synthesized through a novel, facile reflux-based method that

A Bis-Calix[4]pyrrole Enzyme Mimic that Constrains Two Oxoanions in Close Proximity

DEFF Research Database (Denmark)

He, Qing; Kelliher, Michael; Bähring, Steffen

2017-01-01

Herein we describe a large capsule-like bis-calix[4]pyrrole 1 , that is able to host concurrently two dihydrogen phosphate anions within a relatively large internal cavity. Evidence for the concurrent, dual recognition of the encapsulated anions came from 1H NMR and UV-vis spectroscopies and ITC ...

(4-Nitrophenylmethyl 2,3-dihydro-1H-pyrrole-1-carboxylate: crystal structure and Hirshfeld analysis

Directory of Open Access Journals (Sweden)

Julio Zukerman-Schpector

2018-03-01

Full Text Available In the title compound, C12H12N2O4, the dihydropyrrole ring is almost planar (r.m.s. deviation = 0.0049 Å and is nearly coplanar with the adjacent C2O2 residue [dihedral angle = 4.56 (9°], which links to the 4-nitrobenzene substituent [dihedral angle = 4.58 (8°]. The molecule is concave, with the outer rings lying to the same side of the central C2O2 residue and being inclined to each other [dihedral angle = 8.30 (7°]. In the crystal, supramolecular layers parallel to (10-5 are sustained by nitrobenzene-C—H...O(carbonyl and pyrrole-C—H...O(nitro interactions. The layers are connected into a three-dimensional architecture by π(pyrrole–π(nitrobenzene stacking [inter-centroid separation = 3.7414 (10 Å] and nitro-O...π(pyrrole interactions.

Tumor Repression of VCaP Xenografts by a Pyrrole-Imidazole Polyamide

OpenAIRE

Hargrove, Amanda E.; Martinez, Thomas F.; Hare, Alissa A.; Kurmis, Alexis A.; Phillips, John W.; Sud, Sudha; Pienta, Kenneth J; Dervan, Peter B.

2015-01-01

Pyrrole-imidazole (Py-Im) polyamides are high affinity DNA-binding small molecules that can inhibit protein-DNA interactions. In VCaP cells, a human prostate cancer cell line overexpressing both AR and the TMPRSS2-ERG gene fusion, an androgen response element (ARE)-targeted Py-Im polyamide significantly downregulates AR driven gene expression. Polyamide exposure to VCaP cells reduced proliferation without causing DNA damage. Py-Im polyamide treatment also reduced tumor growth in a VCaP mouse ...

Modular synthesis and in vitro and in vivo antimalarial assessment of C-10 pyrrole mannich base derivatives of artemisinin.

Science.gov (United States)

Pacorel, Bénédicte; Leung, Suet C; Stachulski, Andrew V; Davies, Jill; Vivas, Livia; Lander, Hollie; Ward, Stephen A; Kaiser, Marcel; Brun, Reto; O'Neill, Paul M

2010-01-28

In two steps from dihydroartemisinin, a small array of 16 semisynthetic C-10 pyrrole Mannich artemisinin derivatives (7a-p) have been prepared in moderate to excellent yield. In vitro analysis against both chloroquine sensitive and resistant strains has demonstrated that these analogues have nanomolar antimalarial activity, with several compounds being more than 3 times more potent than the natural product artemisinin. In addition to a potent antimalarial profile, these molecules also have very high in vitro therapeutic indices. Analysis of the optimal Mannich side chain substitution for in vitro and in vivo activity reveals that the morpholine and N-methylpiperazine Mannich side chains provide analogues with the best activity profiles, both in vitro and in vivo in the Peter's 4 day test.

Construction of a monoanionic S,N,S-pincer ligand with a pyrrole core by sequential [1,2] phospho-Fries rearrangement. Characterization of palladium and silver coordination complexes

NARCIS (Netherlands)

Fraix, A.; Lutz, M.; Spek, A.L.; Klein Gebbink, R.J.M.; van Koten, G.; Salaun, J. -Y; Jaffrès, P. -A

2010-01-01

The synthesis of an S,NH,S-pincer ligand possessing a pyrrole core and two O,O-diethylthiophosphonyl groups to design PS lateral coordination sites is reported. The synthetic procedure to produce this ligand makes use of the nitrogen atom of the pyrrole heterocycle to successively functionalize the

Preparation and enhanced electrochemical properties of nano-sulfur/poly(pyrrole-co-aniline) cathode material for lithium/sulfur batteries

International Nuclear Information System (INIS)

Qiu Linlin; Zhang Shichao; Zhang Lan; Sun, Mingming; Wang Weikun

2010-01-01

Poly(pyrrole-co-aniline) (PPyA) copolymer nanofibers were prepared by chemical oxidation method with cetyltrimethyl ammonium chloride (CTAC) as template, and the nano-sulfur/poly(pyrrole-co-aniline) (S/PPyA) composite material in lithium batteries was achieved via co-heating the mixture of PPyA and sublimed sulfur at 160 deg. C for 24 h. The component and structure of the materials were characterized by FTIR, Raman, XRD, and SEM. PPyA with nanofiber network structure was employed as a conductive matrix, adsorbing agent and firm reaction chamber for the sulfur cathode materials. The nano-dispersed composite exhibited a specific capacity up to 1285 mAh g -1 in the initial cycle and remained 866 mAh g -1 after 40 cycles.

[18F]fluoromethylated phenyl-pyrroles and 7-azaindole analog as potential dopamine D4 receptor imaging agents

International Nuclear Information System (INIS)

Ji, D. Y.; Oh, S. Z.; Choi, Y. S.; Lee, K. C.; Kim, S. E.; Choi, Y.; Lee, K. H.; Kim, B. T.

1997-01-01

An association between the dopamine D 4 receptor and schizophrenia was recently suggested and the D 4 receptor antagonists may thus have potential in elucidating the role of the receptor in schizophrenic patients. The purpose of this study was to develop some of these antagonists as potential dopamine D 4 receptor imaging agents for PET. We have prepared 1-(3-[ 18 F]fluoromethylphenyl)-3-([4-(pyridin-2-yl)piperazin-1-yl)methyl) pyrrole (1), 1-(3-[ 18 F]fluoromethylphenyl)-3-([4-(pyridin-2-yl)piperazin-1-yl)methyl) pyrrole (2), and 3-([4-(4-[ 18 F]fluoro methylbenzyl)piperazin-1-yl)methyl)-1H-pyrrolo(2,3,-b)pyridine (3) as potential imaging agents for the dopamine D 4 receptor for PET. The compounds [ 18 F]1 and [ 18 F]2 were prepared by coupling of (3-[ 18 F]fluoromethylphenyl)-pyrrol-1- yl-3-aldehyde and the piperazine moiety in the presence of NaBH 3 CN. The [ 18 F]fluorinated aldehyde was obtained in 60-85% yield by the displacement of the corresponding mesylate with F-18-(THF, 90 .deg. C, 5 min). HPLC purification (Alltech Econosil C-18 columm, 250 x 10 mm, 35: 65 = 0.1M NH 4 CI 2 H : CH 3 OH, 4 ml/min, t R =26.6 min) gave the [ 18 F]1 and [ 18 F]2 in 7-12% yield. In the case of azaindole 3, a methlene link was inserted between the piperazinyl and a fluoromethyl phenyl group. Radiochemical synthesis of the [ 18 F]3 was carried out by coupling of the piperazne moiety and [ 18 F]fluoromethylbenzyl mesylate in the presence of NEt 3 (3:1-CH 3 CN: DMF, 120 .deg. C, 30 min). Purification was carried out by HPLC using a C-18 column (Alltech Econosil, 50 x 10 mm, 100% 0.1M NH 4 CO 2 H for 5 min followed by 40:60=0.1 M NH 4 CO 2 H : MeOH, 4 ml/min t R =28.7 min). The time of synthesis including HPLC purification was 100 min. The overall yield of [ 18 F]3 was 10-15% with a radiochemical purity better than 97% and a specific activity greater than 1000 ci/mmol

Kinetics of tritium isotope exchange between liquid pyrrole and gaseous hydrogen

International Nuclear Information System (INIS)

Stolarz, A.

1994-01-01

The kinetics of tritium isotope exchange between liquid pyrrole and gaseous hydrogen has been studied over the temperature range of 290-303 K. The reaction was carried out in the presence of platinum black but in spite of that, it appeared to be relatively slow. The kinetics of the exchange reaction studied could be described by the simple McKay equation. The results obtained suggest that diffusion is the rate-determining step. A mechanism of exchange is proposed. (author) 10 refs.; 2 figs.; 1 tab

Use of Graphite Oxide and Graphene Oxide as Catalysts in the Synthesis of Dipyrromethane and Calix[4]pyrrole

Directory of Open Access Journals (Sweden)

Sweta Mishra

2011-08-01

Full Text Available Graphite oxide and graphene oxides have been used as solid catalysts for the synthesis of 5,5-dialkyldipyrromethanes and calix[4]pyrroles in organic and aqueous solutions at room temperature.

Phase Behaviour of 1-Ethyl-3-methylimidazolium Thiocyanate Ionic Liquid with Catalytic Deactivated Compounds and Water at Several Temperatures: Experiments and Theoretical Predictions

Directory of Open Access Journals (Sweden)

Ramalingam Anantharaj

2011-01-01

Full Text Available Density, surface tension and refractive index were determined for the binary mixture of catalytic deactivated compounds with 1-ethyl-3-methylimidazolium thiocyanate {[EMIM][SCN]} at temperature of (298.15 to 323.15 K. For all the compounds with ILs, the densities varied linearly in the entire mole fraction with increasing temperature. From the obtained data, the excess molar volume and deviation of surface tension and refractive index have been calculated. A strong interaction was found between similar (cation-thiophene or cation-pyrrole compounds. The interaction of IL with dissimilar compounds such as indoline and quinoline and other multiple ring compounds was found to strongly depend on the composition of IL at any temperatures. For the mixtures, the surface tension decreases in the order of: thiophene > quinoline > pyridine > indoline > pyrrole > water. In general from the excess volume studies, the IL-sulphur/nitrogen mixture has stronger interaction as compared to IL-IL, thiophene-thiophene or pyrrole-pyrrole interaction. The deviation of surface tension was found to be inversely proportional to deviation of refractive index. The quantum chemical based COSMO-RS was used to predict the non-ideal liquid phase activity coefficient for all mixtures. It indicated an inverse relation between activity coefficient and excess molar volumes.

Amination of activated carbon for enhancing phenol adsorption: Effect of nitrogen-containing functional groups

International Nuclear Information System (INIS)

Yang, Guo; Chen, Honglin; Qin, Hangdao; Feng, Yujun

2014-01-01

To study the contribution of different nitrogen-containing functional groups to enhancement of phenol adsorption, the aminated activated carbons (AC) were characterized by N2 adsorption/desorption, XPS, Boehm titration, and pH drift method and tested for adsorption behaviors of phenol. Adsorption isotherm fitting revealed that the Langmuir model was preferred for the aminated ACs. The adsorption capacity per unit surface area (q m /SSA BET ) was linearly correlated with the amount of pyridinic and pyrrolic N, which suggested that these two functional groups played a critical role in phenol adsorption. The enhancement of adsorption capacity was attributed to the strengthened π–π dispersion between phenol and basal plane of AC by pyridinic, pyrrolic N. The adsorption kinetics was found to follow the pseudo-second-order kinetic model, and intraparticle diffusion was one of the rate-controlling steps in the adsorption process.

Interaction of derived polymers from pyrrole with biocompatible solutions

International Nuclear Information System (INIS)

Lopez G, O. G.

2010-01-01

This work presents a study about the synthesis by plasma, the electric properties and superficial interaction of polymers derived from pyrrole doped with Iodine with potential use as bio material. Poly-pyrrole is a semiconductor and biocompatible polymer with potential application in the development of artificial muscles and implants where the electric interaction between cells and material is an important variable. The syntheses were made at 13.5 MHz in a glass tubular reactor of 1500 cm 3 with electrodes of 6.5 cm diameter and stainless steel flanges. An electrode was connected to the RF terminal of the power supply that is combined with a matching coupling resistance. The monomer and dopant used in this work were pyrrole and Iodine respectively, in closed containers. They were vaporized and injected separately into the reactor at room temperature and 0.1 mbar. The vapors of the reagents mixed freely in the reactor. The synthesis time was 240 min at 40, 60, 80 and 100 W. The polymers were obtained as thin films adhered to the reactor walls. The films were washed and swollen with distilled water and removed from the reactor walls with a small spatula. The polymers were irradiated with gamma rays at 18 and 22 KGy. Due to the fact that the doses are cumulative, the final dose applied was 40 KGy. The polymers characterization was carried out by Fourier Transform Infrared Spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy, contact angle, electrical conductivity and X-ray diffraction. The analyses indicates that the polymers have very similar structure in almost the entire power range, showing C-O, C=C, C-H, O-H, N-H bonds with a predominantly amorphous structure. The TGA analyses showed that the material has 4 or 5 loses of material. The first one starts after that 115 C except for the material irradiated at 40 KGy, this one begins in 87 C, the second one is in the interval of 196 and 295 C, the third one between 311 and 500 C, and the last

Overcoming incompatibility in elastomer blends by rubber additives with tailored surface properties

NARCIS (Netherlands)

Tiwari, M.; Datta, Rabin; Guo, R.; Talma, Auke; van Ooij, W.J.; Dierkes, Wilma K.; Noordermeer, Jacobus W.M.

2014-01-01

Rubber is a challenging composite material, whose functionality strongly depends on the affinity of the different materials in the composite, and its morphology. One way to tailor polarity and chemistry of the filler surface is plasma coating. When using acetylene, thiophene, or pyrrole as monomers,

Mechanics of active surfaces

Science.gov (United States)

Salbreux, Guillaume; Jülicher, Frank

2017-09-01

We derive a fully covariant theory of the mechanics of active surfaces. This theory provides a framework for the study of active biological or chemical processes at surfaces, such as the cell cortex, the mechanics of epithelial tissues, or reconstituted active systems on surfaces. We introduce forces and torques acting on a surface, and derive the associated force balance conditions. We show that surfaces with in-plane rotational symmetry can have broken up-down, chiral, or planar-chiral symmetry. We discuss the rate of entropy production in the surface and write linear constitutive relations that satisfy the Onsager relations. We show that the bending modulus, the spontaneous curvature, and the surface tension of a passive surface are renormalized by active terms. Finally, we identify active terms which are not found in a passive theory and discuss examples of shape instabilities that are related to active processes in the surface.

3-(Dicyanomethylidene)indan-1-one-Functionalized Calix[4]arene-Calix[4]pyrrole Hybrid: An Ion-Pair Sensor for Cesium Salts.

Science.gov (United States)

Yeon, Yerim; Leem, Soojung; Wagen, Corin; Lynch, Vincent M; Kim, Sung Kuk; Sessler, Jonathan L

2016-09-02

A chromogenic calix[4]arene-calix[4]pyrrole hybrid ion pair receptor bearing an indane substituent at a β-pyrrolic position has been prepared. On the basis of solution-phase UV-vis spectroscopic analysis and (1)H NMR spectroscopic studies carried out in 10% methanol in chloroform, receptor 1 is able to bind only cesium ion pairs (e.g., CsF, CsCl, and CsNO3) but not the constituent cesium cation (as its perchlorate salt) or the F(-), Cl(-), or NO3(-) anions (as the tetrabutylammonium salts). It thus displays rudimentary AND logic gate behavior. Receptor 1 shows a colorimetric response to cesium ion pairs under conditions of solid-liquid (nitrobenzene) and liquid-liquid (D2O-nitrobenzene-d5) extraction.

Electrochemical characteristics of coated steel with poly(N-methyl pyrrole) synthesized in presence of ZnO nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Mahmoudian, M.R., E-mail: M_R_mahmoudian@yahoo.com [Department of Chemistry, University of Malaya, Kuala Lumpur 50603 (Malaysia); Department of Chemistry, Masjed-Soleiman Branch, Islamic Azad University, Masjed-Soleiman (Iran, Islamic Republic of); Basirun, W.J.; Alias, Y. [Department of Chemistry, University of Malaya, Kuala Lumpur 50603 (Malaysia); Khorsand Zak, A. [Low Dimensional Materials Research Center, Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia)

2011-10-31

Poly(N-methyl pyrrole) (PMPy) coating was electrodeposited on steel substrates in mixed electrolytes of dodecyl benzene sulphonic acid with oxalic acid in the absence and the presence of ZnO nanoparticles (NPs). The morphology and compositions were characterized by Field Emission Scanning Electron Microscopy (FESEM), Fourier Transform Infrared Spectroscopy and Energy-dispersive X-ray spectroscopy. Electrode/coating/electrolyte system was studied by Electrochemical Impedance Spectroscopy. The comparison between the pore resistance (R{sub po}) of synthesized PMPy in the absence and presence of ZnO NPs indicated that the existence of ZnO increased the R{sub po} of the coating. The FESEM micrographs indicated that the size of micro-spherical grains in the morphology of PMPy is significantly reduced and the surface area of PMPy is increased with the presence of ZnO NPs. The increase of the ability to interact with the ions liberated during the corrosion reaction of steel and the increase of the rate probability for the occurrence of cathodic reduction of oxygen on the PMPy with the increase of the surface area can be considered as reasons for improvement of protective properties of synthesized PMPy in the presence of ZnO NPs.

Overcoming Incompatibility Problems in Elastomer Blends by Tailored Surface Properties of Rubber Additives

NARCIS (Netherlands)

Dierkes, Wilma K.; Tiwari, M.; Guo, R.; Datta, Rabin; Talma, Auke; Noordermeer, Jacobus W.M.; van Ooij, W.J.

2013-01-01

Rubber is a challenging composite material, whose functionality strongly depends on the affinity of the different materials in the composite and its morphology. One way to tailor polarity and chemistry of the filler surface is plasma coating. When using acetylene, thiophene, or pyrrole as monomers,

Synthesis of Poly pyrrole Inverse Opal in [bmim] Containing Acetonitrile and the Application of the Inverse Opal in Cell Prototype

International Nuclear Information System (INIS)

Yan, W.; Dong, Q.Q.; Sun, L.N.; Deng, W.; Wu, Sh.

2013-01-01

Most primary cells use Zn or Li as the anode, a metallic oxide as the cathode, and an acidic or alkaline solution or moist past as the electrolytic solution. In this paper, highly ordered poly pyrrole (PPy) inverse opals have been successfully synthesized in the acetonitrile solution containing [bmim]PF 6 . PPy films were prepared under the same experimental conditions. Cyclic voltammograms of the PPy film and the PPy inverse opal in neutral phosphate buffer solution (PBS) were recorded. X-ray photoelectron spectroscopy technique was used to investigate the structural surface of the PPy films and the PPy inverse opals. It is found that the PF 6 - anions kept de doping from the PPy films during the potential scanning process, resulting in the electrochemical inactivity. Although PF 6 - anions also kept de doping from the PPy inverse opals, the PO 4 3- anions from PBS could dope into the inverse opal, explaining why the PPy inverse opals kept their electrochemical activity. An environmental friendly cell prototype was constructed, using the PPy inverse opal as the anode. The electrolytes in both the cathodic and anodic half-cells were neutral PBSs. The open-circuit potential of the cell prototype reached 0.487 V and showed a stable output over several hundred hours

Promoter scanning of the human COX-2 gene with 8-ring polyamides: unexpected weakening of polyamide-DNA binding and selectivity by replacing an internal N-Me-pyrrole with β-alanine.

Science.gov (United States)

Bashkin, James K; Aston, Karl; Ramos, Joseph P; Koeller, Kevin J; Nanjunda, Rupesh; He, Gaofei; Dupureur, Cynthia M; David Wilson, W

2013-02-01

Rules for polyamide-DNA recognition have proved invaluable for the design of sequence-selective DNA binding agents in cell-free systems. However, these rules are not fully transferrable to predicting activity in cells, tissues or animals, and additional refinements to our understanding of DNA recognition would help biomedical studies. Similar complexities are encountered when using internal β-alanines as polyamide building blocks in place of N-methylpyrrole; β-alanines were introduced in polyamide designs to maintain good hydrogen bonding registry with the target DNA, especially for long polyamides or those with several GC bp (P.B. Dervan, A.R. Urbach, Essays Contemp. Chem. (2001) 327-339). Thus, to clarify important subtleties of molecular recognition, we studied the effects of replacing a single pyrrole with β-alanine in 8-ring polyamides designed against the Ets-1 transcription factor. Replacement of a single internal N-methylpyrrole with β-alanine to generate a β/Im pairing in two 8-ring polyamides causes a decrease in DNA binding affinity by two orders of magnitude and decreases DNA binding selectivity, contrary to expectations based on the literature. Measurements were made by fluorescence spectroscopy, quantitative DNA footprinting and surface plasmon resonance, with these vastly different techniques showing excellent agreement. Furthermore, results were validated for a range of DNA substrates from small hairpins to long dsDNA sequences. Docking studies helped show that β-alanine does not make efficient hydrophobic contacts with the rest of the polyamide or nearby DNA, in contrast to pyrrole. These results help refine design principles and expectations for polyamide-DNA recognition. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

The Synthesis of Novel 3-Substituted Poly(pyrroles) Bearing Crown-ether Moieties and a Study of their Electrochemical Properties

DEFF Research Database (Denmark)

Guernion, Nicolas J.L.; Blencowe, A.; Hayes, Wayne

2006-01-01

A series of fourteen novel pyrrole monomers substituted at the 3-position with aliphatic and aromatic crown-ether moieties have been synthesised in good yield and characterised extensively. Several of those compounds were electropolymerised successfully in acetonitrile, using both potentiostatic ...

Electropolymerization of pyrrole on oxidizable metal under high frequency ultrasound irradiation. Application of focused beam to a selective masking technique

Energy Technology Data Exchange (ETDEWEB)

Et Taouil, A. [Institut UTINAM, UMR 6213 CNRS, Universite de Franche-Comte, 30 Avenue de l' observatoire, 25009 Besancon Cedex (France); Lallemand, F., E-mail: fabrice.lallemand@univ-fcomte.f [Institut UTINAM, UMR 6213 CNRS, Universite de Franche-Comte, 30 Avenue de l' observatoire, 25009 Besancon Cedex (France); Hallez, L.; Hihn, J-Y. [Institut UTINAM, UMR 6213 CNRS, Universite de Franche-Comte, 30 Avenue de l' observatoire, 25009 Besancon Cedex (France)

2010-12-01

A novel masking technique against polymer deposition based on High Intensity Focused Ultrasound (HIFU) irradiation was developed for the first time. With this in mind, a variety of background salts were tested. Sodium salicylate was found to be the most effective electrolytic medium for pyrrole sonoelectropolymerization on copper as it leads to a very efficient passivating oxide layer preventing copper dissolution while enabling polymer formation independently from sonication. In such a medium, high frequency ultrasound greatly refines surface structure, and a slight increase in doping level is observed. Finally, it was proved that focused ultrasound increases copper dissolution in sodium oxalate electrolyte while preventing polypyrrole deposition. A selected zone on the copper substrate was thus irradiated by the focused ultrasound beam to protect it from polymerization. In a second stage, a self-assembled monolayer was deposited on this polymer-free area to create a surface biphased substrate. This type of masking technique can be proposed as an interesting alternative to lithography as it is easier to carry out and allows chemical waste reduction.

Cation-pi interaction of the univalent silver cation with meso-octamethylcalix[4]pyrrole: Experimental and theoretical study

Czech Academy of Sciences Publication Activity Database

Polášek, Miroslav; Kvíčala, J.; Makrlík, E.; Křížová, Věra; Vaňura, P.

2017-01-01

Roč. 1130, FEB 2017 (2017), s. 408-413 ISSN 0022-2860 Grant - others:GA MŠk(CZ) 20/2015; GA MŠk(CZ) LM2010005 Institutional support: RVO:61388955 Keywords : silver cation * meso-octamethylcalix[4]pyrrole * complexation Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.753, year: 2016

Synthesis and electrochemical properties of novel, donor–acceptor pyrrole derivatives with 1,8-naphthalimide units and their polymers

International Nuclear Information System (INIS)

Ledwon, Przemyslaw; Brzeczek, Alina; Pluczyk, Sandra; Jarosz, Tomasz; Kuznik, Wojciech; Walczak, Krzysztof; Lapkowski, Mieczyslaw

2014-01-01

A new class of bipolar monomers with pyrrole or thiophene–pyrrole–thiophene as electron donor and 1,8-naphthalimide as electron acceptor unit is reported. Donor–acceptor conjugated polymers were generated electrochemically. The synthesis of monomers, optical, electrochemical and spectroelectrochemical properties supported by theoretical calculations are presented. 1,8-naphthalimide units were attached directly to pyrrole in compounds 1a and 2a or by different bridges in the case of 1b and 2b. Intra-molecular donor–acceptor interactions of the monomers and its polymers were investigated using cyclic voltammetry, in-situ UV–Vis-NIR, electron spin resonance (ESR) spectroelectrochemistry and fluorescence spectroscopy. Studied compounds present large discrepancy (up to 1.31 eV for 2a) between energy gap values determined through electrochemical and optical measurements. The Time-dependent density functional theory (TDDFT) calculations help to explain this discrepancy. This is caused by weak HOMO to LUMO transition, 2000 times weaker than HOMO −2 to LUMO or HOMO to LUMO +1 transition. Altering the structure of monomers yields different stability and properties of obtained polymers. The p- and n-doping processes are separated. Anions are localized mainly on 1,8-naphthalimide units. Cations are localized mainly on pyrrole or thiophene–pyrrole–thiophene moiety and their polymer chains. Attachment of the additional thiophene units decreases the oxidation potential of the monomer and reduces the influence of the steric hindrance between 1,8-naphthalimide moiety and polymer/oligomers chain. This new class of model compounds is promising for use as a material with enhanced charge separation for wide range of optoelectronic, electrochromic and photovoltaic applications

Pyrrole-phenylboronic acid: a novel monomer for dopamine recognition and detection based on imprinted electrochemical sensor.

Science.gov (United States)

Zhong, Min; Teng, Ying; Pang, Shufen; Yan, Liqin; Kan, Xianwen

2015-02-15

A molecular imprinting polymer (MIP) based electrochemical sensor was successfully prepared for dopamine (DA) recognition and detection using pyrrole-phenylboronic acid (py-PBA) as a novel electropolymerized monomer. py-PBA could form cyclic boronic ester bond with DA, thus endowing a double recognition capacity of the sensor to DA in the combination of the imprinted effect of MIP. Compared with the sensor prepared using pyrrole or phenylboronic acid as electropolymerized monomer, the present sensor exhibited a remarkable high imprinted factor to DA. The influence factors including pH value, the mole ratio between monomer and template molecule, electropolymerization scan rate, and scan cycles of electropolymerization process were investigated and optimized. Under the optimal conditions, the sensor could recognize DA from its analogs and monosaccharides. A linear ranging from 5.0 × 10(-8) to 1.0 × 10(-5) mol/L for the detection of DA was obtained with a detection limit of 3.3 × 10(-8) mol/L (S/N = 3). The sensor has been applied to analyze DA in injection samples with satisfactory results. Copyright © 2014 Elsevier B.V. All rights reserved.

Emission and absorption of light in poly pyrrole synthesized by plasma

International Nuclear Information System (INIS)

Enriquez, M.A.; Colin, E.; Olayo, M.G.; Cruz, G.J.; Ordonez, E.; Benavides, R.; Morales, J.; Olayo, R.

2007-01-01

The poly pyrrole structure (PPy) consists of heterocyclic rings with conjugation that it depends on the intensity of the electric field applied during the synthesis, and its luminescence is related with the π-π * transitions of that conjugation. To irradiate with light of different wavelengths, the results indicate that the polymer absorbs in the interval from 290 to 700 nm and it emits between 450 and 470 nm. The basal conductivity of the polymers, without electromagnetic excitation, it was measured in 10 -15 S/cm, however, to interact with visible light it is increased approximately 10 times and when excite with UV light it is increased up to 3 magnitude orders. (Author)

Fe{sub 2}O{sub 3}-Poly-pyrrole hybrid nano-composite materials for super-capacitors

Energy Technology Data Exchange (ETDEWEB)

Mallouki, M.; Tran-Van, F.; Sarrazin, C.; Chevrot, C. [Cergy-Pontoise Univ., Lab. de Physicochimie des Polymeres et des Interfaces (LPPI), EA 2528 95 (France); Fauvarque, J.F. [CNAM, Lab. d' Electrochimie Industrielle, 75 - Paris (France); Simon, P. [Universite Paul Sabatier, CIRIMAT-LCMIE, UMR 5085, 31 - Toulouse (France); De, A. [Saha Institute of Nuclear Physics, Calcutta (India)

2004-07-01

Fe{sub 2}O{sub 3}-Poly-pyrrole hybrid nano-composite materials chemically synthesized from colloid particles of iron oxide in aqueous solution have been processed to realize electrode materials for super-capacitor applications. The performances have been evaluated by cyclic voltammetry and galvano-static techniques in a three-electrode cell. The capacitance of Fe{sub 2}O{sub 3}-PPy hybrid nano-composite doped with para-toluene-sulfonate reaches 47 mAh/g in PC/NEt{sub 4}BF{sub 4} with a good stability during cycling (loss of 3% after 1000 cycles). Transmission Electronic Microscopy indicates a porous nano-structure with spherical particles in a range of 400-500 nm which ensures a good accessibility of the electrolyte in the bulk of the electro-active hybrid material. Preliminary studies with room temperature ionic liquid show promising results since the specific capacitance reaches 427 F/g in 1- ethyl-3-methyl-imidazolium bis((tri-fluoro-methyl)sulfonyl)amide (EMITFSI). (authors)

Transition metal doped poly(aniline-co-pyrrole)/multi-walled carbon nanotubes nanocomposite for high performance supercapacitor electrode materials

Energy Technology Data Exchange (ETDEWEB)

Dhibar, Saptarshi; Bhattacharya, Pallab; Hatui, Goutam; Das, C.K., E-mail: chapal12@yahoo.co.in

2015-03-15

Highlights: • The CuCl{sub 2} doped copolymer (PANI and PPy)/MWCNTs nanocomposite was prepared. • The nanocomposite achieved highest specific capacitance of 383 F/g at a 0.5 A/g. • Nanocomposite exhibits better energy density as well as power density. • The nanocomposite also showed better electrical conductivity at room temperature. • The nanocomposite can be used as promising electrode materials for supercapacitor. - Abstract: In this present communication, copolymer of polyaniline (PANI) and polypyrrole (PPy) that is poly(aniline-co-pyrrole) [poly(An-co-Py)], copper chloride (CuCl{sub 2}) doped poly(aniline-co-pyrrole) [poly(An-co-Py) Cu], and CuCl{sub 2} doped poly(aniline-co-pyrrole)/multi walled carbon nanotubes (MWCNTs) [poly(An-co-Py) Cu CNT] nanocomposite have been prepared by a simple and inexpensive in-situ chemical oxidative polymerization method, using ammonium persulfate (APS) as oxidant and hydrochloric acid (HCl) as dopant and investigated as high performance supercapacitor electrode materials. The possible interaction between CuCl{sub 2} with copolymers and MWCNTs was investigated by Fourier transform infrared spectroscopy (FTIR) and UV–visible spectroscopy analysis. The morphological characteristic of all the electrode materials were analyzed by Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM) study. The electrochemical characterizations of all the electrode materials were carried out by three electrode probe method where, standard calomel electrode and platinum were used as reference and counter electrodes, respectively. Among all the electrode materials, poly(An-co-Py) Cu CNT nanocomposite achieved highest specific capacitance value of 383 F/g at 0.5 A/g scan rate. The nanocomposite showed better electrical conductivity at room temperature and also attained nonlinear current–voltage characteristic. Based on the superior electrochemical as well as other properties the as prepared

Transition metal doped poly(aniline-co-pyrrole)/multi-walled carbon nanotubes nanocomposite for high performance supercapacitor electrode materials

International Nuclear Information System (INIS)

Dhibar, Saptarshi; Bhattacharya, Pallab; Hatui, Goutam; Das, C.K.

2015-01-01

Highlights: • The CuCl 2 doped copolymer (PANI and PPy)/MWCNTs nanocomposite was prepared. • The nanocomposite achieved highest specific capacitance of 383 F/g at a 0.5 A/g. • Nanocomposite exhibits better energy density as well as power density. • The nanocomposite also showed better electrical conductivity at room temperature. • The nanocomposite can be used as promising electrode materials for supercapacitor. - Abstract: In this present communication, copolymer of polyaniline (PANI) and polypyrrole (PPy) that is poly(aniline-co-pyrrole) [poly(An-co-Py)], copper chloride (CuCl 2 ) doped poly(aniline-co-pyrrole) [poly(An-co-Py) Cu], and CuCl 2 doped poly(aniline-co-pyrrole)/multi walled carbon nanotubes (MWCNTs) [poly(An-co-Py) Cu CNT] nanocomposite have been prepared by a simple and inexpensive in-situ chemical oxidative polymerization method, using ammonium persulfate (APS) as oxidant and hydrochloric acid (HCl) as dopant and investigated as high performance supercapacitor electrode materials. The possible interaction between CuCl 2 with copolymers and MWCNTs was investigated by Fourier transform infrared spectroscopy (FTIR) and UV–visible spectroscopy analysis. The morphological characteristic of all the electrode materials were analyzed by Field emission scanning electron microscopy (FESEM) and Transmission electron microscopy (TEM) study. The electrochemical characterizations of all the electrode materials were carried out by three electrode probe method where, standard calomel electrode and platinum were used as reference and counter electrodes, respectively. Among all the electrode materials, poly(An-co-Py) Cu CNT nanocomposite achieved highest specific capacitance value of 383 F/g at 0.5 A/g scan rate. The nanocomposite showed better electrical conductivity at room temperature and also attained nonlinear current–voltage characteristic. Based on the superior electrochemical as well as other properties the as prepared nanocomposite can be used

Rhodium(III)-catalyzed [3+2] annulation of 5-aryl-2,3-dihydro-1H-pyrroles with internal alkynes through C(sp²)-H/alkene functionalization.

Science.gov (United States)

Zhou, Ming-Bo; Pi, Rui; Hu, Ming; Yang, Yuan; Song, Ren-Jie; Xia, Yuanzhi; Li, Jin-Heng

2014-10-13

This study describes a new rhodium(III)-catalyzed [3+2] annulation of 5-aryl-2,3-dihydro-1H-pyrroles with internal alkynes using a Cu(OAc)2 oxidant for building a spirocyclic ring system, which includes the functionalization of an aryl C(sp(2))-H bond and addition/protonolysis of an alkene C=C bond. This method is applicable to a wide range of 5-aryl-2,3-dihydro-1H-pyrroles and internal alkynes, and results in the assembly of the spiro[indene-1,2'-pyrrolidine] architectures in good yields with excellent regioselectivities. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Thieno[3,4-c]Pyrrole-4,6-Dione-Based Polymer Acceptors for High Open-Circuit Voltage All-Polymer Solar Cells

KAUST Repository

Liu, Shengjian; Song, Xin; Thomas, Simil; Kan, Zhipeng; Cruciani, Federico; Laquai, Fré dé ric; Bredas, Jean-Luc; Beaujuge, Pierre

2017-01-01

limits the perspectives to meet the 10% efficiency threshold in all-polymer solar cells. This report examines two polymer acceptor analogs composed of thieno[3,4-c]pyrrole-4,6-dione (TPD) and 3,4-difluorothiophene ([2F]T) motifs, and their BHJ solar cell

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

Characterization of poly pyrrole/montmorillonite electro polymerised onto Pt

International Nuclear Information System (INIS)

Castagno, K.R.L.; Azambuja, D.S.; Dalmoro, V.; Mauller, R.S.

2010-01-01

In this study films of polypyrrole/montmorillonite (PPy/MT) were electropolymerized on platinum in order to evaluate the performance of this technique in the preparation of nanocomposite materials and to determine the thermal properties and conductivity of the composites. The films were synthesized from a solution containing pyrrole, dodecylbenzene sulfonate, acid and two types of clays: montmorillonite-Na + (MT-Na) and montmorillonite-30B (MT-M). The characterization of the films we have used FT-IR, TEM, XRD, TGA, DSC and resistivity measurement by the four-point van der Pauw method. The study showed that the adopted method of exfoliation and the electropolymerization method used, allows obtaining nanocomposite materials. Analyses of FT-IR, TEM and XRD show that the clays are exfoliated in the polymer matrix. Thermal analysis of the films indicates that the addition of clay reflects an enhancement in the thermal properties of the matrix of PPy, but decreases the conductivity of the same. (author)

2-[2-(Aziridin-1-ylethyl]-5,5-dimethyl-2,5-dihydro-4H-benzo [e]isoindol-4-one (Cytotoxic Oxonaphthalene-Pyrroles, Part IV

Directory of Open Access Journals (Sweden)

Helmut Spreitzer

2012-10-01

Full Text Available An aziridine-containing side chain is attached to an oxonaphthalene-annelated pyrrole in expectation of DNA alkylating properties. The cytotoxicity is evaluated against two cell lines, KB-31 and KB-8511, respectively.

Synthesis and spectroscopic characterization of a fluorescent pyrrole derivative containing electron acceptor and donor groups

Science.gov (United States)

Almeida, A. K. A.; Monteiro, M. P.; Dias, J. M. M.; Omena, L.; da Silva, A. J. C.; Tonholo, J.; Mortimer, R. J.; Navarro, M.; Jacinto, C.; Ribeiro, A. S.; de Oliveira, I. N.

2014-07-01

The synthesis and fluorescence characterization of a new pyrrole derivative (PyPDG) containing the electron donor-acceptor dansyl substituent is reported. The effects of temperature and solvent polarity on the steady-state fluorescence of this compound are investigated. Our results show that PyPDG exhibits desirable fluorescent properties which makes it a promising candidate to be used as the photoactive material in optical thermometry and thermography applications. Further, the electrochemical and emission properties of polymeric films obtained from the oxidation polymerization of PyPDG are also analyzed.

Thieno[3,4-c]pyrrole-4,6-dione-3,4-difluorothiophene Polymer Acceptors for Efficient All-Polymer Bulk Heterojunction Solar Cells

KAUST Repository

Liu, Shengjian

2016-09-16

Branched-alkyl-substituted poly(thieno[3,4-c]pyrrole-4,6-dione-alt-3,4-difluorothiophene) (PTPD[2F]T) can be used as a polymer acceptor in bulk heterojunction (BHJ) solar cells with a low-band-gap polymer donor (PCE10) commonly used with fullerenes. The

Selective Determination of Serotonin on Poly(3,4-ethylenedioxy pyrrole)-single-walled Carbon Nanotube-Modified Glassy Carbon Electrodes

International Nuclear Information System (INIS)

Kim, Seul Ki; Bae, Si Ra; Ahmed, Mohammad Shamsuddin; You, Jung Min; Jeon, Seung Won

2011-01-01

An electrochemically-modified electrode [P(EDOP-SWNTs)/GCE] was prepared by electropolymerization of 3,4-ethylenedioxy pyrrole (EDOP) single-walled carbon nanotubes (SWNTs) on the surface of a glassy carbon electrode (GCE) and characterized by SEM, CV, and DPV. This modified electrode was employed as an electrochemical biosensor for the selective determination of serotonin concentrations at pH 7.4 and exhibited a typical enhanced effect on the current response of serotonin with a lower oxidation overpotential. The linear response was in the range of 1.0 x 10"-"7 to 1.0 x 10"-"5 M, with a correlation coefficient of 0.998 on the anodic current. The lower detection limit was calculated as 5.0 nM. Due to the relatively low currents and difference of potentials in the electrochemical responses of uric acid (UA), ascorbic acid (AA), and dopamine (DA), the modified electrode was a useful and effective sensing device for the selective and sensitive serotonin determination in the presence of UA, AA, and DA

Selective Determination of Serotonin on Poly(3,4-ethylenedioxy pyrrole)-single-walled Carbon Nanotube-Modified Glassy Carbon Electrodes

Energy Technology Data Exchange (ETDEWEB)

Kim, Seul Ki; Bae, Si Ra; Ahmed, Mohammad Shamsuddin; You, Jung Min; Jeon, Seung Won [Chonnam National University, Gwangju (Korea, Republic of)

2011-04-15

An electrochemically-modified electrode [P(EDOP-SWNTs)/GCE] was prepared by electropolymerization of 3,4-ethylenedioxy pyrrole (EDOP) single-walled carbon nanotubes (SWNTs) on the surface of a glassy carbon electrode (GCE) and characterized by SEM, CV, and DPV. This modified electrode was employed as an electrochemical biosensor for the selective determination of serotonin concentrations at pH 7.4 and exhibited a typical enhanced effect on the current response of serotonin with a lower oxidation overpotential. The linear response was in the range of 1.0 x 10{sup -7} to 1.0 x 10{sup -5} M, with a correlation coefficient of 0.998 on the anodic current. The lower detection limit was calculated as 5.0 nM. Due to the relatively low currents and difference of potentials in the electrochemical responses of uric acid (UA), ascorbic acid (AA), and dopamine (DA), the modified electrode was a useful and effective sensing device for the selective and sensitive serotonin determination in the presence of UA, AA, and DA.

Ferrocene-Functionalized 4-(2,5-Di(thiophen-2-yl-1H-pyrrol-1-ylaniline: A Novel Design in Conducting Polymer-Based Electrochemical Biosensors

Directory of Open Access Journals (Sweden)

Rukiye Ayranci

2015-01-01

Full Text Available Herein, we report a novel ferrocenyldithiophosphonate functional conducting polymer and its use as an immobilization matrix in amperometric biosensor applications. Initially, 4-(2,5-di(thiophen-2-yl-1H-pyrrol-1-ylamidoferrocenyldithiophosphonate was synthesized and copolymerized with 4-(2,5-di(thiophen-2-yl-1H-pyrrol-1-ylbenzenamine at graphite electrodes. The amino groups on the polymer were utilized for covalent attachment of the enzyme glucose oxidase. Besides, ferrocene on the backbone was used as a redox mediator during the electrochemical measurements. Prior to the analytical characterization, optimization studies were carried out. The changes in current signals at +0.45 V were proportional to glucose concentration from 0.5 to 5.0 mM. Finally, the resulting biosensor was applied for glucose analysis in real samples and the data were compared with the spectrophotometric Trinder method.

Surface-Activated Coupling Reactions Confined on a Surface.

Science.gov (United States)

Dong, Lei; Liu, Pei Nian; Lin, Nian

2015-10-20

Chemical reactions may take place in a pure phase of gas or liquid or at the interface of two phases (gas-solid or liquid-solid). Recently, the emerging field of "surface-confined coupling reactions" has attracted intensive attention. In this process, reactants, intermediates, and products of a coupling reaction are adsorbed on a solid-vacuum or a solid-liquid interface. The solid surface restricts all reaction steps on the interface, in other words, the reaction takes place within a lower-dimensional, for example, two-dimensional, space. Surface atoms that are fixed in the surface and adatoms that move on the surface often activate the surface-confined coupling reactions. The synergy of surface morphology and activity allow some reactions that are inefficient or prohibited in the gas or liquid phase to proceed efficiently when the reactions are confined on a surface. Over the past decade, dozens of well-known "textbook" coupling reactions have been shown to proceed as surface-confined coupling reactions. In most cases, the surface-confined coupling reactions were discovered by trial and error, and the reaction pathways are largely unknown. It is thus highly desirable to unravel the mechanisms, mechanisms of surface activation in particular, of the surface-confined coupling reactions. Because the reactions take place on surfaces, advanced surface science techniques can be applied to study the surface-confined coupling reactions. Among them, scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) are the two most extensively used experimental tools. The former resolves submolecular structures of individual reactants, intermediates, and products in real space, while the latter monitors the chemical states during the reactions in real time. Combination of the two methods provides unprecedented spatial and temporal information on the reaction pathways. The experimental findings are complemented by theoretical modeling. In particular, density

Rhodium enalcarbenoids: direct synthesis of indoles by rhodium(II)-catalyzed [4+2] benzannulation of pyrroles.

Science.gov (United States)

Dawande, Sudam Ganpat; Kanchupalli, Vinaykumar; Kalepu, Jagadeesh; Chennamsetti, Haribabu; Lad, Bapurao Sudam; Katukojvala, Sreenivas

2014-04-14

Disclosed herein is the design of an unprecedented electrophilic rhodium enalcarbenoid which results from rhodium(II)-catalyzed decomposition of a new class of enaldiazo compounds. The synthetic utility of these enalcarbenoids has been successfully demonstrated in the first transition-metal-catalyzed [4+2] benzannulation of pyrroles, thus leading to substituted indoles. The new benzannulation has been applied to the efficient synthesis of the natural product leiocarpone as well as a potent adipocyte fatty-acid binding protein inhibitor. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Control of charge transfer by conformational and electronic effects: Donor-donor and donor-acceptor phenyl pyrroles

International Nuclear Information System (INIS)

Neubauer, Antje; Bendig, Juergen; Rettig, Wolfgang

2009-01-01

Derivatives of N-pyrrolobenzene with a para-donor and a para-acceptor substituent on the benzene ring are compared. It is shown that by a suitable increase of the donor strength of the pyrrolo group, CT fluorescence can be achieved even for donor-donor-substituted benzenes. The ICT emission for sterically hindered compounds is more forbidden than that of unhindered phenyl pyrroles. This suggests conformational effects which induce a narrower twist angle distribution around a perpendicular minimum in the excited state.

Conjugated and fluorescent polymer based on dansyl-substituted pyrrole prepared by electrochemical polymerization in acetonitrile containing boron trifluoride diethyl etherate

International Nuclear Information System (INIS)

Almeida, Andresa K.A.; Dias, Jéssica M.M.; Silva, Ana Julia C.; Santos, Diego P.; Navarro, Marcelo; Tonholo, Josealdo; Goulart, Marília O.F.; Ribeiro, Adriana S.

2014-01-01

Graphical abstract: - Highlights: • A fluorescent pyrrole derivative bearing a dansyl substituent (PyPDG) was synthesized. • PyPDG was electropolymerized onto ITO in (C 4 H 9 ) 4 NBF 4 /CH 3 CN/BFEE mixed electrolyte. • The resulting polymer (PPyPDG) films displayed electrochromic behavior. • PPyPDG is a good green light emitter material. - Abstract: A fluorescent pyrrole derivative bearing a dansyl substituent was prepared by a simple synthetic route and electropolymerized onto Indium Tin Oxide (ITO) electrodes. The presence of the dansyl group in the monomer precursor prevents the electropolymerization in usual systems, such as (C 4 H 9 ) 4 NBF 4 in acetonitrile (CH 3 CN). For this reason, it was added 20% boron trifluoride diethyl etherate (BFEE) to this system, to achieve electropolymerization. The resulting poly[3-(N-pyrrolyl)propyl dansylglycinate] (PPyPDG) films displayed electrochromic behavior. Their color varied from greenish-yellow, in the neutral state, to greyish-green, in the oxidized state; moreover PPyPDG is a good green light emitter material. Therefore, PPyPDG films might be potentially applicable in displays and optoelectronic devices

Metabolic activation of pyrrolizidine alkaloids: insights into the structural and enzymatic basis.

Science.gov (United States)

Ruan, Jianqing; Yang, Mengbi; Fu, Peter; Ye, Yang; Lin, Ge

2014-06-16

Pyrrolizidine alkaloids (PAs) are natural toxins widely distributed in plants. The toxic potencies of different PAs vary significantly. PAs are mono- or diesters of necine acids with a necine base. On the basis of the necine bases, PAs are classified into three types: retronecine-type, otonecine-type, and platynecine-type. Hepatotoxic PAs contain an unsaturated necine base. PAs exert hepatotoxicity through metabolic activation by hepatic cytochromes P450s (CYPs) to generate reactive intermediates which form pyrrole-protein adducts. These adducts provide a mechanism-based biomarker to assess PA toxicity. In the present study, metabolic activation of 12 PAs from three structural types was investigated first in mice to demonstrate significant variations in hepatic metabolic activation of different PAs. Subsequently, the structural and enzymatic factors affecting metabolic activation of these PAs were further investigated by using human liver microsomes and recombinant human CYPs. Pyrrole-protein adducts were detected in the liver and blood of mice and the in vitro systems treated with toxic retronecine-type and otonecine-type PAs having unsaturated necine bases but not with a platynecine-type PA containing a saturated necine base. Retronecine-type PAs produced more pyrrole-protein adducts than otonecine-type PAs with similar necine acids, demonstrating that the structure of necine base affected PA toxic potency. Among retronecine-type PAs, open-ring diesters generated the highest amount of pyrrole-protein adducts, followed by macrocyclic diesters, while monoesters produced the least. Only CYP3A4 and CYP3A5 activated otonecine-type PAs, while all 10 CYPs studied showed the ability to activate retronecine-type PAs. Moreover, the contribution of major CYPs involved also varied significantly among retronecine-type PAs. In conclusion, our findings provide a scientific basis for predicting the toxicities of individual PAs in biological systems based on PA structural

Tumor Repression of VCaP Xenografts by a Pyrrole-Imidazole Polyamide.

Directory of Open Access Journals (Sweden)

Amanda E Hargrove

Full Text Available Pyrrole-imidazole (Py-Im polyamides are high affinity DNA-binding small molecules that can inhibit protein-DNA interactions. In VCaP cells, a human prostate cancer cell line overexpressing both AR and the TMPRSS2-ERG gene fusion, an androgen response element (ARE-targeted Py-Im polyamide significantly downregulates AR driven gene expression. Polyamide exposure to VCaP cells reduced proliferation without causing DNA damage. Py-Im polyamide treatment also reduced tumor growth in a VCaP mouse xenograft model. In addition to the effects on AR regulated transcription, RNA-seq analysis revealed inhibition of topoisomerase-DNA binding as a potential mechanism that contributes to the antitumor effects of polyamides in cell culture and in xenografts. These studies support the therapeutic potential of Py-Im polyamides to target multiple aspects of transcriptional regulation in prostate cancers without genotoxic stress.

Ferrocene-functionalized 4-(2,5-Di(thiophen-2-yl)-1H-pyrrol-1-yl)aniline: a novel design in conducting polymer-based electrochemical biosensors.

Science.gov (United States)

Ayranci, Rukiye; Demirkol, Dilek Odaci; Ak, Metin; Timur, Suna

2015-01-13

Herein, we report a novel ferrocenyldithiophosphonate functional conducting polymer and its use as an immobilization matrix in amperometric biosensor applications. Initially, 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)amidoferrocenyldithiophosphonate was synthesized and copolymerized with 4-(2,5-di(thiophen-2-yl)-1H-pyrrol-1-yl)benzenamine at graphite electrodes. The amino groups on the polymer were utilized for covalent attachment of the enzyme glucose oxidase. Besides, ferrocene on the backbone was used as a redox mediator during the electrochemical measurements. Prior to the analytical characterization, optimization studies were carried out. The changes in current signals at +0.45 V were proportional to glucose concentration from 0.5 to 5.0 mM. Finally, the resulting biosensor was applied for glucose analysis in real samples and the data were compared with the spectrophotometric Trinder method.

High electrochemical capacitor performance of oxygen and nitrogen enriched activated carbon derived from the pyrolysis and activation of squid gladius chitin

Science.gov (United States)

Raj, C. Justin; Rajesh, Murugesan; Manikandan, Ramu; Yu, Kook Hyun; Anusha, J. R.; Ahn, Jun Hwan; Kim, Dong-Won; Park, Sang Yeup; Kim, Byung Chul

2018-05-01

Activated carbon containing nitrogen functionalities exhibits excellent electrochemical property which is more interesting for several renewable energy storage and catalytic applications. Here, we report the synthesis of microporous oxygen and nitrogen doped activated carbon utilizing chitin from the gladius of squid fish. The activated carbon has large surface area of 1129 m2 g-1 with microporous network and possess ∼4.04% of nitrogen content in the form of pyridinic/pyrrolic-N, graphitic-N and N-oxide groups along with oxygen and carbon species. The microporous oxygen/nitrogen doped activated carbon is utilize for the fabrication of aqueous and flexible supercapacitor electrodes, which presents excellent electrochemical performance with maximum specific capacitance of 204 Fg-1 in 1 M H2SO4 electrolyte and 197 Fg-1 as a flexible supercapacitor. Moreover, the device displays 100% of specific capacitance retention after 25,000 subsequent charge/discharge cycles in 1 M H2SO4 electrolyte.

Grafting of palladium nanoparticles onto mesoporous molecular sieve MCM-41: Heterogeneous catalysts for the formation of an N-substituted pyrrol

Czech Academy of Sciences Publication Activity Database

Demel, Jan; Čejka, Jiří; Bakardjieva, Snejana; Štěpnička, P.

2007-01-01

Roč. 263, 1-2 (2007), s. 259-265 ISSN 1381-1169 R&D Projects: GA ČR GA104/05/0192; GA MŠk(CZ) LC06070 Institutional research plan: CEZ:AV0Z40400503; CEZ:AV0Z40320502 Keywords : palladium * nanoparticles * MCM-41 * pyrrol * catalysis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.707, year: 2007

Quadrupolar, emission-tunable pi-expanded 1,4-dihydropyrrolo 3,2-b pyrroles - synthesis and optical properties

DEFF Research Database (Denmark)

Janiga, A.; Bednarska, D.; Thorsted, B.

2014-01-01

elucidated by comparison with simpler tetraaryl-analogues. The strong charge-transfer characteristic of these functional dyes can be illustrated by large Stokes shifts (4100-7100 cm(-1)) for A-D-A architectures. The replacement of phenyl rings at positions 2 and 5 with the arylethynylaryl substituents......The synthesis and optical characterization of six novel heteroaromatic-based chromophores is described. The new dyes present mostly an A-D-A general framework, where A is an electron-deficient aromatic ring and D is an electron-rich pyrrolo[3,2-b] pyrrole moiety, linked via triple bonds...

Preparation of deuterated heterocyclic five-membered ring compounds (furan, thiophene, pyrrole, and derivatives) by base-catalyzed hydrogen isotope exchange with deuterium oxide

International Nuclear Information System (INIS)

Heinrich, K.H.; Herrmann, M.; Moebius, G.; Sprinz, H.

1984-01-01

Several deuterated heterocyclic compounds of the type of furan,thiophene and pyrrole were prepared by base-catalyzed proton exchange with deuterium oxide at temperatures above 423 K in a closed system. The determination of deuterium and its distribution within the molecules was carried out by mass spectrometry and 1 H nmr spectrometry. (author)

Fragmentation dynamics of size selected pyrrole clusters prepared by electron impact ionization: Forming a solvated dimer ion core

Czech Academy of Sciences Publication Activity Database

Profant, V.; Poterya, Viktoriya; Fárník, Michal; Slavíček, P.; Buck, U.

2007-01-01

Roč. 111, č. 49 (2007), s. 12477-12486 ISSN 1089-5639 R&D Projects: GA AV ČR KAN400400651; GA ČR GA203/06/1290 Grant - others:GA ČR GP203/07/P449; University Grant(CZ) 8113-10/257852 Institutional research plan: CEZ:AV0Z40400503 Source of funding: V - iné verejné zdroje Keywords : pyrrole cluster s * structure * dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.918, year: 2007

Surface active monomers synthesis, properties, and application

CERN Document Server

Borzenkov, Mykola

2014-01-01

This brief includes information on the background?of and development of synthesis of various types of surface active monomers. The authors explain the importance of utilization of surface active monomers for creation of surface active polymers? and the various biomedical applications of such compounds . This brief introduces techniques for the synthesis of novel types of surface active monomers, their colloidal and polymerizable properties and application for needs of medicine and biology.

Ordering effects in benzo[1,2-b:4,5-b']difuran-thieno[3,4-c]pyrrole-4,6- dione polymers with >7% solar cell efficiency

KAUST Repository

Warnan, Julien; Cabanetos, Clement; El Labban, Abdulrahman; Hansen, Michael Ryan; Tassone, Christopher J.; Toney, Michael F.; Beaujuge, Pierre

2014-01-01

Benzo[1,2-b:4,5-b']difuran-thieno[3,4-c]pyrrole-4,6-dione (PBDFTPD) polymers prepared by microwave-assisted synthesis can achieve power conversion efficiencies (PCEs) >7% in bulk-heterojunction solar cells with phenyl-C61/71-butyric acid methyl

Calix[2]pyreno[2]pyrrole as a Fluorescence Chemical Probe for Polynitroaromatics

International Nuclear Information System (INIS)

Park, Kyung Hwa; Yoo, Jae Duk; Lee, Chang Hee; Ka, Jae Won

2012-01-01

We have demonstrated that the new, readily synthesized and well characterized calix pyreno pyrrole fluorescence molecular probe can detect polynitroaromatic compounds with high affinity. In addition, this highly fluorescent neutral molecular receptor also exhibits enhanced binding affinity towards TNT which is associated with the formation of a pi-complex. The dynamic nature of the current system may enable it to serve as an excellent scaffold for electron-deficient guest molecular binding. Studies for other neutral molecules including metal ions are under in active progress. The elevated selectivity and sensitivity for specific analytes are the core requirements for an ideal chemical probes. A signal induced by guest binding must be sensitive enough so that accurate real time monitoring could be satisfactorily achieved. Introduction of signaling units at suitable places in which they can directly interact with the recognition events is critical in designing chemosensors. Among various signaling events, fluorescence changes are often applied for the sensitive detection of various analytes. An easy modulation of the photochemical properties of the signaling units is an additional advantage in compatibility and applications. Chemosensors for the detection of explosives becomes important due to their immediate applications in remedation of explosive manufacturing sites, homeland security or forensic sciences. With that in mind, numerous methods for the explosive detection have been reported in recent years. Nevertheless, some detection methods sometimes require sophisticated instrumentation which is not easy for on-site testing

Diethyl 2,2′-({[1,4-phenylenebis(azanediyl]bis(methylene}bis(1H-pyrrole-2,1-diyldiacetate

Directory of Open Access Journals (Sweden)

Jasim Alshawi

2016-01-01

Full Text Available The complete molecule of the title compound, C24H30N4O4, is generated by crystallographic inversion symmetry. The molecule is S-shaped and the pyrrole groups have an anti or trans confirmation with respect to the central benzene ring, to which they are inclined by 76.38 (9°. In the crystal, molecules are linked via C—H...O hydrogen bonds, forming layers parallel to the ac plane. Within the layers there are C—H...π interactions present. There are, however, no significant interactions between the layers.

Detection of heavy metal ions in contaminated water by surface plasmon resonance based optical fibre sensor using conducting polymer and chitosan.

Science.gov (United States)

Verma, Roli; Gupta, Banshi D

2015-01-01

Optical fibre surface plasmon resonance (SPR) based sensor for the detection of heavy metal ions in the drinking water is designed. Silver (Ag) metal and indium tin oxide (ITO) are used for the fabrication of the SPR probe which is further modified with the coating of pyrrole and chitosan composite. The sensor works on the wavelength interrogation technique and is capable of detecting trace amounts of Cd(2+), Pb(2+), and Hg(2+) heavy metal ions in contaminated water. Four types of sensing probes are fabricated and characterised for heavy metal ions out of these pyrrole/chitosan/ITO/Ag coated probe is found to be highly sensitive among all other probes. Further, the cadmium ions bind strongly to the sensing surface than other ions and due to this the sensor is highly sensitive for Cd(2+) ions. The sensor's performance is best for the low concentrations of heavy metal ions and its sensitivity decreases with the increasing concentration of heavy metal ions. Copyright © 2014 Elsevier Ltd. All rights reserved.

The activity of the pyrrole insecticide chlorfenapyr in mosquito bioassay: towards a more rational testing and screening of non-neurotoxic insecticides for malaria vector control.

Science.gov (United States)

Oxborough, Richard M; N'Guessan, Raphael; Jones, Rebecca; Kitau, Jovin; Ngufor, Corine; Malone, David; Mosha, Franklin W; Rowland, Mark W

2015-03-24

The rapid selection of pyrethroid resistance throughout sub-Saharan Africa is a serious threat to malaria vector control. Chlorfenapyr is a pyrrole insecticide which shows no cross resistance to insecticide classes normally used for vector control and is effective on mosquito nets under experimental hut conditions. Unlike neurotoxic insecticides, chlorfenapyr owes its toxicity to disruption of metabolic pathways in mitochondria that enable cellular respiration. A series of experiments explored whether standard World Health Organization (WHO) guidelines for evaluation of long-lasting insecticidal nets, developed through testing of pyrethroid insecticides, are suitable for evaluation of non-neurotoxic insecticides. The efficacy of WHO recommended cone, cylinder and tunnel tests was compared for pyrethroids and chlorfenapyr. To establish bioassay exposure times predictive of insecticide-treated net (ITN) efficacy in experimental hut trials, standard three-minute bioassays of pyrethroid and chlorfenapyr ITNs were compared with longer exposures. Mosquito behaviour and response to chlorfenapyr ITN in bioassays conducted at night were compared to day and across a range of temperatures representative of highland and lowland transmission. Standard three-minute bioassay of chlorfenapyr produced extremely low levels of mortality compared to pyrethroids. Thirty-minute day-time bioassay produced mortality closer to hut efficacy of chlorfenapyr ITN but still fell short of the WHO threshold. Overnight tunnel test with chlorfenapyr produced 100% mortality and exceeded the WHO threshold of 80%. The endogenous circadian activity rhythm of anophelines results in inactivity by day and raised metabolism and flight activity by night. A model which explains improved toxicity of chlorfenapyr ITN when tested at night, and during the day at higher ambient temperature, is that activation of chlorfenapyr and disruption of respiratory pathways is enhanced when the insect is more metabolically

Property-based design and synthesis of new chloroquine hybrids via simple incorporation of 2-imino-thiazolidine-4-one or 1h-pyrrol-2, 5-dione fragments on the 4-amino-7-chloroquinoline side chain

International Nuclear Information System (INIS)

Rojas, Fernando A.; Kouznetsov, Vladimir V.

2011-01-01

In the present work, the syntheses of new 4-amino-7-chloroquinoline N-derivatives were performed by selective modification of the side chain amino group of N-(7-chloroquinoline-4-yl) alkyldiamines, basis framework of chloroquine (CQ) drug through the incorporation of heterocyclic 2-imino-thiazolidine-4-one and 1 H-pyrrol-2,5-dione systems. These potential activity modulators were selected thanks to their characteristic properties, and evaluated by virtual screening employing the OSIRIS and Molinspirations platforms. Designed and synthesized quinolinic derivatives could increase the antimalarial activity of CQ analogues without affecting the lipophilicity as described in literature, suggesting them as candidates for further biological assessments. (author)

Property-based design and synthesis of new chloroquine hybrids via simple incorporation of 2-imino-thiazolidine-4-one or 1h-pyrrol-2, 5-dione fragments on the 4-amino-7-chloroquinoline side chain

Energy Technology Data Exchange (ETDEWEB)

Rojas, Fernando A; Kouznetsov, Vladimir V., E-mail: kouznet@uis.edu.co [Laboratorio de Quimica Organica y Biomolecular, Escuela de Quimica, Universidad Industrial de Santander, Bucaramanga (Colombia)

2011-09-15

In the present work, the syntheses of new 4-amino-7-chloroquinoline N-derivatives were performed by selective modification of the side chain amino group of N-(7-chloroquinoline-4-yl) alkyldiamines, basis framework of chloroquine (CQ) drug through the incorporation of heterocyclic 2-imino-thiazolidine-4-one and {sup 1}H-pyrrol-2,5-dione systems. These potential activity modulators were selected thanks to their characteristic properties, and evaluated by virtual screening employing the OSIRIS and Molinspirations platforms. Designed and synthesized quinolinic derivatives could increase the antimalarial activity of CQ analogues without affecting the lipophilicity as described in literature, suggesting them as candidates for further biological assessments. (author)

Electron-deficient N-alkyloyl derivatives of thieno[3,4-c]pyrrole-4,6-dione yield efficient polymer solar cells with open-circuit voltages > 1 v

KAUST Repository

Warnan, Julien; Cabanetos, Clement; Bude, Romain; El Labban, Abdulrahman; LI, LIANG; Beaujuge, Pierre

2014-01-01

Poly(benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymer donors yield some of the highest open-circuit voltages (V OC, ca. 0.9 V) and fill factors (FF, ca. 70%) in conventional bulk-heterojunction (BHJ) solar cells

Ion vs. ion pair receptor: NMR and DFT study of the interaction of Thallium and Cesium ions and ion pairs with meso-octamethylcalix[4]pyrrole

Czech Academy of Sciences Publication Activity Database

Kříž, Jaroslav; Dybal, Jiří; Makrlík, E.; Sedláková, Zdeňka

2012-01-01

Roč. 400, 25 May (2012), s. 19-28 ISSN 0301-0104 R&D Projects: GA ČR GA203/09/1478 Institutional research plan: CEZ:AV0Z40500505 Keywords : calix[4]pyrrole * cesium receptor * fluoride receptor Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.957, year: 2012

Preparation, Surface and Pore Structure of High Surface Area Activated Carbon Fibers from Bamboo by Steam Activation

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Xiaojun Ma

2014-06-01

Full Text Available High surface area activated carbon fibers (ACF have been prepared from bamboo by steam activation after liquefaction and curing. The influences of activation temperature on the microstructure, surface area and porosity were investigated. The results showed that ACF from bamboo at 850 °C have the maximum iodine and methylene blue adsorption values. Aside from the graphitic carbon, phenolic and carbonyl groups were the predominant functions on the surface of activated carbon fiber from bamboo. The prepared ACF from bamboo were found to be mainly type I of isotherm, but the mesoporosity presented an increasing trend after 700 °C. The surface area and micropore volume of samples, which were determined by application of the Brunauer-Emmett-Teller (BET and t-plot methods, were as high as 2024 m2/g and 0.569 cm3/g, respectively. It was also found that the higher activation temperature produced the more ordered microcrystalline structure of ACF from bamboo.

Autoassemblage de macromolécules biologiques via des poly(pyrroles) et/ou des nanotubes de carbone fonctionnalisés

OpenAIRE

Baur , Jessica

2010-01-01

This work is dedicated to the development of hybrid assemblies based on polymers and biomolecules with or without carbon nanotubes with the aim to show their applications in different areas such as biosensors or bio-fuel cells. Firstly, poly(pyrrole-NTA)/Cu2+ was used for the elaboration of DNA or enzymatic biosensors. So, it was able to be used with its affinity partner, histidine, for the reversible immobilization of oligonucleotide probes tagged with histidines. Thanks to a detection witho...

Effects of nitrogen- and oxygen-containing functional groups of activated carbon nanotubes on the electrochemical performance in supercapacitors

Science.gov (United States)

Liu, Haiyan; Song, Huaihe; Chen, Xiaohong; Zhang, Su; Zhou, Jisheng; Ma, Zhaokun

2015-07-01

A kind of nitrogen- and oxygen-containing activated carbon nanotubes (ACNTs) has been prepared by carbonization and activation of polyaniline nanotubes obtained by rapidly mixed reaction. The ACNTs show oxygen content of 15.7% and nitrogen content of 2.97% (atomic ratio). The ACNTs perform high capacitance and good rate capability (327 F g-1 at the current density of 10 A g-1) when used as the electrode materials for supercapacitors. Hydrogen reduction has been further used to investigate the effects of surface functional groups on the electrochemical performance. The changes for both structural component and electrochemical performance reveal that the quinone oxygen, pyridinic nitrogen, and pyrrolic nitrogen of carbon have the most obvious influence on the capacitive property because of their pseudocapacitive contributions.

meso-Octamethylcalix[4]pyrrole as an effective macrocyclic receptor for the univalent thallium cation in the gas phase: Experimental and theoretical study

Czech Academy of Sciences Publication Activity Database

Polášek, Miroslav; Makrlík, E.; Kvíčala, J.; Křížová, Věra; Vaňura, P.

Roč. 1153 ( 2018 ), s. 78-84 ISSN 0022-2860 R&D Projects: GA MŠk CZ.1.05/3.2.00/08.0144 Grant - others:GA MŠk(CZ) 20/2015; GA MŠk(CZ) LM2010005 Institutional support: RVO:61388955 Keywords : Thallium cation * meso-Octamethylcalix[4]pyrrole * Complexation * DFT calculations * Structures Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.753, year: 2016

Homogeneous near surface activity distribution by double energy activation for TLA

International Nuclear Information System (INIS)

Takacs, S.; Ditroi, F.; Tarkanyi, F.

2007-01-01

Thin layer activation (TLA) is a versatile tool for activating thin surface layers in order to study real-time the surface loss by wear, corrosion or erosion processes of the activated parts, without disassembling or stopping running mechanical structures or equipment. The research problem is the determination of the irradiation parameters to produce point-like or large area optimal activity-depth distribution in the sample. Different activity-depth profiles can be produced depending on the type of the investigated material and the nuclear reaction used. To produce activity that is independent of the depth up to a certain depth is desirable when the material removed from the surface by wear, corrosion or erosion can be collected completely. By applying dual energy irradiation the thickness of this quasi-constant activity layer can be increased or the deviation of the activity distribution from a constant value can be minimized. In the main, parts made of metals and alloys are suitable for direct activation, but by using secondary particle implantation the wear of other materials can also be studied in a surface range a few micrometers thick. In most practical cases activation of a point-like spot (several mm 2 ) is enough to monitor the wear, corrosion or erosion, but for special problems relatively large surfaces areas of complicated spatial geometry need to be activated uniformly. Two ways are available for fulfilling this task, (1) production of large area beam spot or scanning the beam over the surface in question from the accelerator side, or (2) a programmed 3D movement of the sample from the target side. Taking into account the large variability of tasks occurring in practice, the latter method was chosen as the routine solution in our cyclotron laboratory

Synthesis, reactions and biological activity of 3-arylidene-5-(4-methylphenyl-2(3H-furanones

Directory of Open Access Journals (Sweden)

ASIF HUSAIN

2009-02-01

Full Text Available 3-Arylidene-5-(4-methylphenyl-2(3H-furanones 2a–m were prepared from 3-(4-methyl-benzoylpropanoic acid 1 and several aromatic aldehydes. Some of the selected furanones were reacted with ammonia gas and benzylamine to give corresponding 3-arylidene-1,3-dihydro-5-(4-methylphenyl-2H-pyrrol-2-ones 3a–h and 3-arylidene-1-benzyl-1,3-dihydro-5-(4-methylphenyl-2H-pyrrol-2-ones 4a–f, respectively, which were characterized on the basis of IR, 1H-NMR, mass spectral data and elemental analysis results. These compounds were tested for their anti-inflammatory and antibacterial activities. The compounds, which showed significant anti-inflammatory activity, were further screened for their analgesic and ulcerogenic activities. Three new compounds (2e, 2h and 4d, out of twenty-seven showed very good anti-inflammatory activity in the carrageenan induced rat paw edema test, with significant analgesic activity in the acetic acid induced writhing test together with negligible ulcerogenic action. The antibacterial activity is expressed as the corresponding MIC values.

Structure and spectroscopic properties of N,S-coordinating 2-methylsulfanyl-N-[(1H-pyrrol-2-ylmethylidene]aniline methanol monosolvate

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D. Douglas Richards

2015-10-01

Full Text Available The reaction of pyrrole-2-carboxaldehyde and 2-(methylsulfanylaniline in refluxing methanol gave an olive-green residue in which yellow crystals of the title compound, C12H12N2S·CH3OH, were grown from slow evaporation of methanol at 263 K. In the crystal, hydrogen-bonding interactions link the aniline molecule and a nearby methanol solvent molecule. These units are linked by a pair of weak C—H...Omethanol interactions, forming inversion dimers consisting of two main molecules and two solvent molecules.

Linear side chains in benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c] pyrrole-4,6-dione polymers direct self-assembly and solar cell performance

KAUST Repository

Cabanetos, Clement; El Labban, Abdulrahman; Bartelt, Jonathan A.; Douglas, Jessica D.; Mateker, William R.; Frechet, Jean; McGehee, Michael D.; Beaujuge, Pierre

2013-01-01

role that linear side-chain substituents play in poly(benzo[1,2-b:4,5-b′]dithiophene-thieno[3,4-c]pyrrole-4,6-dione) (PBDTTPD) polymers for bulk heterojunction (BHJ) solar cell applications. We show that replacing branched side chains by linear ones

Cation Recognition: Novel Potentiometric PVC-Membrane Sensor based on Meso-octamethylcalix[4]pyrrole for the Determination of Trace Amounts of Titanium (III) Ions

International Nuclear Information System (INIS)

Saeid Ahmadzadeh; Anuar Kassim Majid Rezayi

2011-01-01

The present work deals with developing a novel high selective membrane electrode based on meso-octamethylcalix[4]pyrrole for accurate determination of trace amount of titanium (III) ions in real sample solutions. The amounts of ionophore (4 mg), PVC (33 mg), dioctyl phthalate (DOP) as plasticizer (62.8 mg) and sodium tetrakis [3,5-bis (trifluoromethyl) phenyl] borate (NaTFPB) as an ionic additive (0.2 mg) were optimized in the preparation of the membrane. The electrode exhibited a linear response with a near Nernstian slope of 29.49±0.16 (mV per decade of activity) over the pH range from 1 to 3 with a satisfactory concentration range of 1.0 x 10 -6 to 1.0 x x10 -2 M. The developed sensor exhibited good reproducibility over a period of about 3 months with a fast response time of 15 seconds. (author)

Amphoteric surface active agents

Directory of Open Access Journals (Sweden)

Eissa, A.M. F.

1995-10-01

Full Text Available 2-[trimethyl ammonium, triethyl ammonium, pyridinium and 2-amino pyridinium] alkanoates, four series of surface active agents containing carbon chain C₁₂, C₁₄, C₁₆ and C₁₈carbon atoms, were prepared. Their structures were characterized by microanalysis, infrared (IR and nuclear magnetic resonance (NMR. Surface and interfacial tension, Krafft point, wetting time, emulsification power, foaming height and critical micelle concentration (cmc were determined and a comparative study was made between their chemical structure and surface active properties. Antimicrobial activity of these surfactants was also determined.

Se prepararon cuatro series de agentes tensioactivos del tipo 2-[trimetil amonio, trietil amonio, piridinio y 2-amino piridinio] alcanoatos, que contienen cadenas carbonadas con C₁₂, C₁₄, C₁₆ y C₁₈ átomos de carbono.
Se determinaron la tensión superficial e interfacial, el punto de Krafft, el tiempo humectante, el poder de emulsionamiento, la altura espumante y la concentración critica de miscela (cmc y se hizo un estudio comparativo entre la estructura química y sus propiedades tensioactivas. Se determinó también la actividad antimicrobiana de estos tensioactivos. Estas estructuras se caracterizaron por microanálisis, infrarrojo (IR y resonancia magnética nuclear (RMN.

Photophysical properties of fullerenes prepared in an atmosphere of pyrrole

Energy Technology Data Exchange (ETDEWEB)

Glenis, S.; Cooke, S.; Chen, X.; Labes, M.M. (Temple Univ., Philadelphia, PA (United States))

1994-10-01

Samples of C[sub 60] and C[sub 70] containing a variety of nitrogen-doped species were prepared by arc vaporization of graphite in the presence of pyrrole. Cage-doped fractions were isolated by column chromatography and characterized by mass spectroscopy, optical absorption, and fluorescence measurements. Mass spectra were consistent with the substitution of an even number of carbon atoms of the C[sub 60] and C[sub 70] cages by nitrogen atoms. Carbonaceous clusters including fragmented fullerenes containing hydrogen atoms were also formed. UV-visible spectral analysis indicated that there is an influence of the molecular weight on the fundamental [pi]-[pi]* electronic transition. Fluorescence spectra showed a broad band containing vibrational fine structure that is attributed to photoseparated charges in the fragmented fullerenes and a shoulder on the low-energy side that is related to intrinsic excitation in the nitrogen-doped species. Fluorescence results imply a bandgap of 2.36 eV for the N doped fullerenes and the existence of intermediate excitonic transitions below the optical bandgap. Although it has not yet been possible to isolate a pure cage-doped material, the photophysical studies add credence to their existence and the importance of further attempts at their isolation. 17 refs., 4 figs., 1 tab.

The Effect of Laser Surface Reconstruction of Disordered Carbons on Performance

International Nuclear Information System (INIS)

EVEN JR., WILLIAM R.; GUIDOTTI, RONALD A.

1999-01-01

The reconstruction of the surface of disordered carbons was examined by heating carbons derived from polymethacrylonitrile (PMAN) and divinylbenzene (DVB) with a pulsed infrared laser in an argon or helium atmosphere, both fluidized and under static conditions. By graphitizing the outer surface of the carbons, it was hoped to reduce the high first-cycle losses associated with such disordered materials in Li-ion cells. The power to the sample was varied to observed the effects on surface morphology and electrochemical performance in 1M LiPF(sub 6) ethylene carbonate-dimethyl carbonate. The use various reactive atmosphere such as ethylene, 2-vinylpyridine, pyrrole, and furfuryl alcohol were also evaluated as an alternative means of hopefully forming a thin graphitic layer on the carbon particles to reduce first-cycle irreversibility. While some improvement was realized, these losses were still unacceptably high. The laser heating did improve the rate capabilities of the carbons, however. More work in this area is necessary to fully understand surface and bulk effects

Iodine-catalyzed diazo activation to access radical reactivity.

Science.gov (United States)

Li, Pan; Zhao, Jingjing; Shi, Lijun; Wang, Jin; Shi, Xiaodong; Li, Fuwei

2018-05-17

Transition-metal-catalyzed diazo activation is a classical way to generate metal carbene, which are valuable intermediates in synthetic organic chemistry. An alternative iodine-catalyzed diazo activation is disclosed herein under either photo-initiated or thermal-initiated conditions, which represents an approach to enable carbene radical reactivity. This metal-free diazo activation strategy were successfully applied into olefin cyclopropanation and epoxidation, and applying this method to pyrrole synthesis under thermal-initiated conditions further demonstrates the unique reactivity using this method over typical metal-catalyzed conditions.

Biocatalytic ammonolysis of (5S)-4,5-dihydro-1H-pyrrole-1,5-dicarboxylic acid, 1-(1,1-dimethylethyl)-5-ethyl ester: preparation of an intermediate to the dipeptidyl peptidase IV inhibitor Saxagliptin.

Science.gov (United States)

Gill, Iqbal; Patel, Ramesh

2006-02-01

An efficient biocatalytic method has been developed for the conversion of (5S)-4,5-dihydro-1H-pyrrole-1,5-dicarboxylic acid, 1-(1,1-dimethylethyl)-5-ethyl ester (1) into the corresponding amide (5S)-5-aminocarbonyl-4,5-dihydro-1H-pyrrole-1-carboxylic acid, 1-(1,1-dimethylethyl)ester (2), which is a critical intermediate in the synthesis of the dipeptidyl peptidase IV (DPP4) inhibitor Saxagliptin (3). Candida antartica lipase B mediates ammonolysis of the ester with ammonium carbamate as ammonia donor to yield up to 71% of the amide. The inclusion of Ascarite and calcium chloride as adsorbents for carbon dioxide and ethanol byproducts, respectively, increases the yield to 98%, thereby offering an efficient and practical alternative to chemical routes which yield 57-64%.

Facile Syntheses and Molecular-Docking of Novel Substituted 3,4-Dimethyl-1H-pyrrole-2-carboxamide/carbohydrazide Analogues with Antimicrobial and Antifungal Properties

Directory of Open Access Journals (Sweden)

Jitendra D. Bhosale

2018-04-01

Full Text Available The article describes the use of facile one-pot, high-yielding reactions to synthesize substituted 3,4-dimethyl-1H-pyrrole-2-carboxamides 3a–m and carbohydrazide analogues 5a–l as potential antifungal and antimicrobial agents. The structural identity and purity of the synthesized compounds were assigned based on appropriate spectroscopic techniques. Synthesized compounds were assessed in vitro for antifungal and antibacterial activity. The compounds 5h, 5i and 5j were found to be the most potent against Aspergillus fumigatus, with MIC values of 0.039 mg/mL. The compound 5f bearing a 2, 6-dichloro group on the phenyl ring was found to be the most active broad spectrum antibacterial agent with a MIC value of 0.039 mg/mL. The mode of action of the most promising antifungal compounds (one representative from each series; 3j and 5h was established by their molecular docking with the active site of sterol 14α-demethylase. Molecular docking studies revealed a highly spontaneous binding ability of the tested compounds in the access channel away from catalytic heme iron of the enzyme, which suggested that the tested compounds inhibit this enzyme and would avoid heme iron-related deleterious side effects observed with many existing antifungal compounds.

Pyrrolizidine Alkaloids: Metabolic Activation Pathways Leading to Liver Tumor Initiation.

Science.gov (United States)

Fu, Peter P

2017-01-17

Pyrrolizidine alkaloids (PAs) and PA N-oxides are a class of phytochemical carcinogens contained in over 6000 plant species spread around the world. It has been estimated that approximately half of the 660 PAs and PA N-oxides that have been characterized are cytotoxic, genotoxic, and tumorigenic. It was recently determined that a genotoxic mechanism of liver tumor initiation mediated by PA-derived DNA adducts is a common metabolic activation pathway of a number of PAs. We proposed this set of PA-derived DNA adducts could be a common biological biomarker of PA exposure and a potential biomarker of PA-induced liver tumor formation. We have also found that several reactive secondary pyrrolic metabolites can dissociate and interconvert to other secondary pyrrolic metabolites, resulting in the formation of the same exogenous DNA adducts. This present perspective reports the current progress on these new findings and proposes future research needed for obtaining a greater understanding of the role of this activation pathway and validating the use of this set of PA-derived DNA adducts as a biological biomarker of PA-induced liver tumor initiation.

Acid-base characteristics of powdered-activated-carbon surfaces

Energy Technology Data Exchange (ETDEWEB)

Reed, B.E. (West Virginia Univ., Morgantown (United States)); Jensen, J.N.; Matsumoto, M.R. (State Univ. of New York, Buffalo (United States))

Adsorption of heavy metals onto activated carbon has been described using the surface-complex-formation (SCF) model, a chemical equilibrium model. The SCF model requires a knowledge of the amphoteric nature of activated carbon prior to metal adsorption modeling. In the past, a single-diprotic-acid-site model had been employed to describe the amphoteric nature of activated-carbon surfaces. During this study, the amphoteric nature of two powdered activated carbons were investigated, and a three-monoprotic site surface model was found to be a plausible alternative. The single-diprotic-acid-site and two-monoprotic-site models did not describe the acid-base behavior of the two carbons studied adequately. The two-diprotic site was acceptable for only one of the study carbons. The acid-base behavior of activated carbon surfaces seem to be best modeled as a series of weak monoprotic acids.

Active Surface Compensation for Large Radio Telescope Antennas

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Congsi Wang

2018-01-01

Full Text Available With the development of radio telescope antennas with large apertures, high gain, and wide frequency bands, compensation methods, such as mechanical or electronic compensation, are obviously essential to ensure the electrical performance of antennas that work in complex environments. Since traditional compensation methods can only adjust antenna pointing but not the surface accuracy, which are limited for obtaining high surface precision and aperture efficiency, active surface adjustment has become an indispensable tool in this field. Therefore, the development process of electrical performance compensation methods for radio telescope antennas is introduced. Further, a series of analyses of the five key technologies of active surface adjustment is presented. Then, four typical large antennas that have been designed with active main reflector technology are presented and compared. Finally, future research directions and suggestions for reflector antenna compensation methods based on active surface adjustment are presented.

Preparation of thin α-particle sources using poly-pyrrole films functionalized by a chelating agent

International Nuclear Information System (INIS)

Mariet, C.

2000-01-01

This work takes place in the scope of analysis of the α-particle emitting elements U, Pu and Am present in compound environmental matrix like sols and sediments. The samples diversity and above all the α-ray characteristics require the analyst to implement a sequence of chemical steps in which the more restricting is the actinides concentration in a uniform and thin layer en allowing an accurately measure of alpha activity. On this account, we studied a new technique for radioactive sources preparation based on tow steps: preparation of a thin film as source support; incorporation of radioactive elements by a chelating extraction mechanism. The thin films were obtained through electro-polymerization of pyrrole monomer functionalized by an chelating ligand able to extract actinides from concentrated acidic solutions. Polymerization conditions of this monomer were perfected, then obtained films were characterized from a physico-chemical point of view. We point out their extracting properties were comparable to (retention capacity, distribution coefficient) to those of usual ion-exchange resins. The underscore of uranyl and americium nitrate complexes formed in the thin layer allowed to calculate the extraction constants in case acid extraction is negligible. Thanks to this results, the values of the coefficients distribution D U and D Am could be provided for all nitric solutions in which acid extraction is negligible. Optimal actinides retention conditions in the polymer were defined and used to settle a protocol for plutonium analysis in environmental samples. (author)

[Detection of surface EMG signal using active electrode].

Science.gov (United States)

He, Qinghua; Peng, Chenglin; Wu, Baoming; Wang, He

2003-09-01

Research of surface electromyogram(EMG) signal is important in rehabilitation medicine, sport medicine and clinical diagnosis, accurate detection of signal is the base of quantitative analysis of surface EMG signal. In this article were discussed how to reduce possible noise in the detection of surface EMG. Considerations on the design of electrode unit were presented. Instrumentation amplifier AD620 was employed to design a bipolar active electrode for use in surface EMG detection. The experiments showed that active electrode could be used to improve signal/noise ratio, reduce noise and detect surface EMG signal effectively.

Rational Design and Synthesis of Biologically Active Disubstituted 2(3H) Furanones and Pyrrolone Derivatives as Potent and Safer Non Steroidal Anti-inflammatory Agents.

Science.gov (United States)

Khokra, S L; Khan, S A; Choudhary, D; Hasan, S M; Ahmad, A; Husain, Asif

2016-01-01

Furanone and pyrrolone heterocyclic ring system represent important and interesting classes of bioactive compounds. Medicinal chemists use these heterocycyclic moieties as scaffolds in drug design and discovery. A series of 3-arylidene-5-(naphthalene-2-yl)-furan-2(3H)-ones (2a-j) were synthesized by incorporating pharmacophore of COX-2 inhibitor rofecoxib and naphthyl ring of naproxen as potential non steroidal anti-inflammatory agents. These furanone derivatives were subsequently reacted with dry ammonia gas and benzylamine to furnish corresponding 3-arylidene-5-(naphthlen-2-yl)-1H-pyrrol-2(3H)-ones (3a-e) and 3-arylidene-1-benzyl-5- (naphthalene-2-yl)-1H-pyrrol-2(3H)-ones (4a-e), respectively. The newly prepared heterocyclics were screened for their expected in-vivo biological activities including anti-inflammatory, analgesic and ulcerogenic actions in rodents. The COX-2 inhibitory behavior of synthesized compounds was also assessed via automated docking studies. The chemical structure of the synthesized compounds was characterized by using modern spectroscopic techniques. Result of in-vivo pharmacological studies demonstrated that almost all N-Benzyl-pyrrol-2(3H)-ones (4a-e) showed better anti-inflammatory and analgesic activities in comparison with the other two series of furan-2(3H)-ones and pyrrol- 2(3H)-ones. The moldock score value of the tested compounds was found in the range of -116.66 to -170.328 and was better than the standard drug. Among all the synthesized compounds, only nine compounds (2d, 2g, 2h, 3d, 4a, 4b, 4c, 4d and 4e) exhibited potent anti-inflammatory and analgesic activities with significantly reduced gastrointestinal toxicity in various animal models in comparison to standard drug, diclofenac. Therefore, it is recommended to explore the potential of the synthesized compounds as lead candidates for the development of new therapeutic agents.

Lack of effect of deferoxamine, dimethyl sulfoxide, and catalase on monocrotaline pyrrole pulmonary injury

International Nuclear Information System (INIS)

Bruner, L.H.; Johnson, K.; Carpenter, L.J.; Roth, R.A.

1987-01-01

Monocrotaline pyrrole (MCTP) is a reactive metabolite of the pyrrolizidine alkaloid monocrotaline. MCTP given intravenously to rats causes pulmonary hypertension and right ventricular hypertrophy. Lesions in lungs after MCTP treatment contain macrophages and neutrophils, which may contribute to the damage by generation of reactive oxygen metabolites. Rats were treated with MCTP and agents known to protect against oxygen radical-mediated damage in acute models of neutrophil-dependent lung injury. Rats received MCTP and deferoxamine mesylate (DF), dimethyl sulfoxide (DMSO), or polyethylene glycol-coupled catalase (PEG-CAT). MCTP/vehicle-treated controls developed lung injury manifested as increased lung weight, release of lactate dehydrogenase into the airway, and sequestration of 125 I-labeled bovine serum albumin in the lungs. Cotreatment of rats with DF, DMSO, or PEG-CAT did not protect against the injury due to MCTP. These results suggest that toxic oxygen metabolites do not play an important role in the pathogenesis of MCTP-induced pulmonary injury

Lack of effect of deferoxamine, dimethyl sulfoxide, and catalase on monocrotaline pyrrole pulmonary injury

Energy Technology Data Exchange (ETDEWEB)

Bruner, L.H.; Johnson, K.; Carpenter, L.J.; Roth, R.A.

1987-01-01

Monocrotaline pyrrole (MCTP) is a reactive metabolite of the pyrrolizidine alkaloid monocrotaline. MCTP given intravenously to rats causes pulmonary hypertension and right ventricular hypertrophy. Lesions in lungs after MCTP treatment contain macrophages and neutrophils, which may contribute to the damage by generation of reactive oxygen metabolites. Rats were treated with MCTP and agents known to protect against oxygen radical-mediated damage in acute models of neutrophil-dependent lung injury. Rats received MCTP and deferoxamine mesylate (DF), dimethyl sulfoxide (DMSO), or polyethylene glycol-coupled catalase (PEG-CAT). MCTP/vehicle-treated controls developed lung injury manifested as increased lung weight, release of lactate dehydrogenase into the airway, and sequestration of SVI-labeled bovine serum albumin in the lungs. Cotreatment of rats with DF, DMSO, or PEG-CAT did not protect against the injury due to MCTP. These results suggest that toxic oxygen metabolites do not play an important role in the pathogenesis of MCTP-induced pulmonary injury.

Mechanochemical activation and gallium and indiaarsenides surface catalycity

Science.gov (United States)

Kirovskaya, I. A.; Mironova, E. V.; Umansky, I. V.; Brueva, O. Yu; Murashova, A. O.; Yureva, A. V.

2018-01-01

The present work has been carried out in terms of determining the possibilities for a clearer identification of the active sites nature, intermediate surface compounds nature, functional groups during adsorption and catalysis, activation of the diamond-like semiconductors surface (in particular, the AIIIBV type) based on mechanochemical studies of the “reaction medium (H2O, iso-C3H7OH) - dispersible semiconductor (GaAs, InAs)” systems. As a result, according to the read kinetic curves of dispersion in water, both acidification and alkalinization of the medium have been established and explained; increased activity of the newly formed surface has been noted; intermediate surface compounds, functional groups appearing on the real surface and under H2O adsorption conditions, adsorption and catalytic decomposition of iso-C3H7OH have been found (with explanation of the origin). The unconcealed role of coordinatively unsaturated atoms as active sites of these processes has been shown; the relative catalytic activity of the semiconductors studied has been evaluated. Practical recommendations on the preferred use of gallium arsenide in semiconductor gas analysis and semiconductor catalysis have been given in literature searches, great care should be taken in constructing both.

Active Surfaces and Interfaces of Soft Materials

Science.gov (United States)

Wang, Qiming

A variety of intriguing surface patterns have been observed on developing natural systems, ranging from corrugated surface of white blood cells at nanometer scales to wrinkled dog skins at millimeter scales. To mimetically harness functionalities of natural morphologies, artificial transformative skin systems by using soft active materials have been rationally designed to generate versatile patterns for a variety of engineering applications. The study of the mechanics and design of these dynamic surface patterns on soft active materials are both physically interesting and technologically important. This dissertation starts with studying abundant surface patterns in Nature by constructing a unified phase diagram of surface instabilities on soft materials with minimum numbers of physical parameters. Guided by this integrated phase diagram, an electroactive system is designed to investigate a variety of electrically-induced surface instabilities of elastomers, including electro-creasing, electro-cratering, electro-wrinkling and electro-cavitation. Combing experimental, theoretical and computational methods, the initiation, evolution and transition of these instabilities are analyzed. To apply these dynamic surface instabilities to serving engineering and biology, new techniques of Dynamic Electrostatic Lithography and electroactive anti-biofouling are demonstrated.

Rhodium/Silver-Cocatalyzed Transannulation of N-Sulfonyl-1,2,3-triazoles with Vinyl Azides: Divergent Synthesis of Pyrroles and 2 H-Pyrazines.

Science.gov (United States)

Zhang, Lin; Sun, Ge; Bi, Xihe

2016-11-07

The first cyclization reaction between vinyl azides and N-sulfonyl-1,2,3-triazoles is reported. A Rh/Ag binary metal catalyst system proved to be necessary for the successful cyclization. By varying the structure of vinyl azides, such reaction allows the divergent synthesis of pyrroles and 2H-pyrazines. The cyclization reactions feature a broad substrate scope, good functional group tolerance, high reaction efficiency, and good to high product yields. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Low-frequency active surface plasmon optics on semiconductors

NARCIS (Netherlands)

Gómez Rivas, J.; Kuttge, M.; Kurz, H.; Haring Bolivar, P.; Sánchez-Gil, J.A.

2006-01-01

A major challenge in the development of surface plasmon optics or plasmonics is the active control of the propagation of surface plasmon polaritons (SPPs). Here, we demonstrate the feasibility of low-frequency active plasmonics using semiconductors. We show experimentally that the Bragg scattering

Surface activation of dyed fabric for cellulase treatment.

Science.gov (United States)

Schimper, Christian B; Ibanescu, Constanta; Bechtold, Thomas

2011-10-01

Surface activation of fabric made from cellulose fibres, such as viscose, lyocell, modal fibres and cotton, can be achieved by printing of a concentrated NaOH-containing paste. From the concentration of reducing sugars formed in solution, an increase in intensity of the cellulase hydrolysis by a factor of six to eight was observed, which was mainly concentrated at the activated parts of the fabric surface. This method of local activation is of particular interest for modification of materials that have been dyed with special processes to attain an uneven distribution of dyestuff within the yarn cross-section, e.g., indigo ring-dyed denim yarn for jeans production. Fabrics made from regenerated cellulose fibres were used as model substrate to express the effects of surface activation on indigo-dyed material. Wash-down experiments on indigo-dyed denim demonstrated significant colour removal from the activated surface at low overall weight loss of 4-5%. The method is of relevance for a more eco-friendly processing of jeans in the garment industry. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Asymmetric supercapacitor based on graphene oxide/polypyrrole composite and activated carbon electrodes

International Nuclear Information System (INIS)

Fan, Le-Qing; Liu, Gui-Jing; Wu, Ji-Huai; Liu, Lu; Lin, Jian-Ming; Wei, Yue-Lin

2014-01-01

Graphene oxide/polypyrrole (GO/PPy) composite is synthesized by in situ oxidation polymerization of pyrrole (Py) in the presence of GO and used for supercapacitor electrode. The scanning electron microscope (SEM) observes that PPy nanoparticles are uniformly grown on the surfaces of GO sheets, leading to increase both the specific surface area and the electrical conductivity of material. GO/PPy composite exhibits better electrochemical performances than the pure individual components. When the mass ratio of GO to Py is 10:100, the GO/PPy composite electrode shows the highest capacitance of 332.6 F g −1 , and presents high rate capability. An asymmetric supercapacitor is fabricated by using the optimized GO/PPy composite as positive electrode and activated carbon (AC) as negative electrode. The asymmetric supercapacitor can be cycled reversibly in the voltage range of 0–1.6 V, and exhibits the maximum energy density of 21.4 Wh kg −1 at a power density of 453.9 W kg −1 . Furthermore, the GO/PPy//AC asymmetric supercapacitor displays good rate capability and excellent cyclic durability

Structure and spectroscopic properties of N,S-coordinating 2-methyl-sulfanyl-N-[(1H-pyrrol-2-yl)methyl-idene]aniline methanol monosolvate.

Science.gov (United States)

Richards, D Douglas; Ang, M Trisha C; McDonald, Robert; Bierenstiel, Matthias

2015-10-01

The reaction of pyrrole-2-carboxaldehyde and 2-(methyl-sulfan-yl)aniline in refluxing methanol gave an olive-green residue in which yellow crystals of the title compound, C12H12N2S·CH3OH, were grown from slow evaporation of methanol at 263 K. In the crystal, hydrogen-bonding inter-actions link the aniline mol-ecule and a nearby methanol solvent mol-ecule. These units are linked by a pair of weak C-H⋯Omethanol interactions, forming inversion dimers consisting of two main molecules and two solvent molecules.

Ferricyanide confined into the integrative system of pyrrolic surfactant and SWCNTs: The enhanced electrochemial sensing of paracetamol

International Nuclear Information System (INIS)

Wu, Xiao-Yan; Niu, Wen-Jun; Cosnier, Serge; Deng, Sheng-Yuan; Zhang, Xue-Ji; Shan, Dan

2015-01-01

Highlights: • Amphiphilic surfactant derived from pyrrole was used to construct a special microheterogeneous system incorporated with SWCNTs by electropolymerization. • Common redox probe, Fe(CN) 6 3−/4− , was captured into this microheterogeneous system due to the cooperation interactions of electrostatic and π-π stacking. • A dramatically negative shift in the half wave potential compared to Fe(CN) 6 3−/4− in aqueous solution can be obtained due to the unusual Fe(CN) 6 3−/4− partitioning. • The entrapped Fe(CN) 6 3−/4− was applied in the construction of the enhanced electrochemical sensor to paracetamol. - Abstract: An enhanced paracetamol sensor was developed based on the integrative system of single walled carbon nanotubes (SWCNTs) and the pyrrolic surfactant, (11-pyrrolyl-1-yl-undecyl)triethylammonium tetrafluoroborate (A 2 ), in which confined the redox probe, Fe(CN) 6 3−/4− . A well-defined redox peaks of the firmly confined Fe(CN) 6 3−/4− with dramatically negative shift in the half-wave potential compared to Fe(CN) 6 3−/4− in aqueous solution was observed at GCE/polyA 2 -Fe(CN) 6 3−/4− /SWCNTs. To understand the unusual Fe(CN) 6 3−/4− partitioning in this microheterogeneous system, the responses of the Fe(CN) 6 3−/4− at the electrodes modified by SWCNTs, polyA 2 , SWCNTs/polyA 2 , and polyA 2 /SWCNTs were investigated, respectively. The results of cyclic voltammetry (CV) and differential pulse voltammetry (DPV) indicated that the proposed electrode exhibiting efficient electrocatalytic capability towards the paracetamol oxidation. Thereafter, an amperometric assay for paracetamol at GCE/polyA 2 -Fe(CN) 6 3−/4− /SWCNTs was developed at 0.4 V with an enhanced linear range from 3.4×10 −7 ∼7.98 × 10 −4 M.

Study of metal specific interaction, F-LUMO and VL shift to understand interface of CuPc thin films and noble metal surfaces

Energy Technology Data Exchange (ETDEWEB)

Sinha, Sumona; Mukherjee, M., E-mail: manabendra.mukherjee@saha.ac.in

2015-10-30

Graphical abstract: - Highlights: • F-LUMO, a hybridized state near E{sub F} confirms partial charge transfer. • Non-significant role of partial charge transfer in VL shift over push back effect. • Pyrrole sites affected for partial charge transfer from Cu and Ag substrates. • Negligible effect on pyrrole cites for Pt and Au substrates. - Abstract: The performances of organic electronic devices are significantly associated with their energy level alignment at organic semiconductor/metal–electrode interfaces. The electronic character of an organic semiconducting molecular over-layer on a metal surface can vary from semiconducting to metallic, depending on the nature of the molecular orbitals with respect to the Fermi level of the electrode. The general tendency of extrapolating established models for single crystal substrates to ‘real’ device substrates is highly misleading. Hence, the importance of metal specific interaction, former lowest unoccupied molecular orbital (F-LUMO) and vacuum level (VL) shift have been investigated as a function of thickness of the deposited films by means of photoelectron spectroscopy (XPS and UPS) to understand the interface between CuPc and Cu, Ag, Pt and Au foils sequentially. The XPS data provides the signature of affectability of pyrrole sites of CuPc molecules for partial charge transfer from Cu and Ag substrates while a negligible effect on pyrrole cites resulted for Pt and Au substrates. Furthermore, the appearance of F-LUMO, a hybridized state close to the Fermi level gives confirmatory information about partial charge transfer. Contrary to the general belief that vacuum level shift caused by charge transfer can partially or totally cancel that for push back effect, our observation indicates that the partial charge transfer does not play significant role in the shift of vacuum level. The entire thickness dependent electronic energy level alignment of CuPc films on all noble metal substrates is explained in terms

Study of metal specific interaction, F-LUMO and VL shift to understand interface of CuPc thin films and noble metal surfaces

International Nuclear Information System (INIS)

Sinha, Sumona; Mukherjee, M.

2015-01-01

Graphical abstract: - Highlights: • F-LUMO, a hybridized state near E_F confirms partial charge transfer. • Non-significant role of partial charge transfer in VL shift over push back effect. • Pyrrole sites affected for partial charge transfer from Cu and Ag substrates. • Negligible effect on pyrrole cites for Pt and Au substrates. - Abstract: The performances of organic electronic devices are significantly associated with their energy level alignment at organic semiconductor/metal–electrode interfaces. The electronic character of an organic semiconducting molecular over-layer on a metal surface can vary from semiconducting to metallic, depending on the nature of the molecular orbitals with respect to the Fermi level of the electrode. The general tendency of extrapolating established models for single crystal substrates to ‘real’ device substrates is highly misleading. Hence, the importance of metal specific interaction, former lowest unoccupied molecular orbital (F-LUMO) and vacuum level (VL) shift have been investigated as a function of thickness of the deposited films by means of photoelectron spectroscopy (XPS and UPS) to understand the interface between CuPc and Cu, Ag, Pt and Au foils sequentially. The XPS data provides the signature of affectability of pyrrole sites of CuPc molecules for partial charge transfer from Cu and Ag substrates while a negligible effect on pyrrole cites resulted for Pt and Au substrates. Furthermore, the appearance of F-LUMO, a hybridized state close to the Fermi level gives confirmatory information about partial charge transfer. Contrary to the general belief that vacuum level shift caused by charge transfer can partially or totally cancel that for push back effect, our observation indicates that the partial charge transfer does not play significant role in the shift of vacuum level. The entire thickness dependent electronic energy level alignment of CuPc films on all noble metal substrates is explained in terms of a

Effects of Surface Treatment of Activated Carbon on Its Surface and Cr(VI) Adsorption Characteristics

Energy Technology Data Exchange (ETDEWEB)

Park, Soo Jin; Jang, Yu Sin [Advanced Materials Division., Korea Research Institute of Chimical Technology, Taejon (Korea)

2001-04-01

In this work, the effect of surface treatments on activated carbons (ACs) has been studied in the context of gas and liquid adsorption behaviors. The chemical solutions used in this experiment were 35% sodium hydroxide, and these were used for the acidic and basic treatments, respectively. The surface properties have been determined by pH, acid-base values, and FT-IR. The adsorption isotherms of Cr(VI) ion on activated carbons have been studied with the 5 mg/l concentration at ambient temperature. N{sub 2} adsorption isotherm characteristics, which include the specific surface area, micro pore volume, and microporosity, were determined by BET and Boer's-plot methods. In case of the acidic treatment of activated carbons, it was observed that the adsorption of Cr(VI) ion was more effective due to the increase acid value (or acidic functional group) of activated carbon surfaces. However, the basic treatment on activated carbons was caused no significant effects, probably due to the decreased specific surface area and total pore volume. 27 refs., 7 figs., 4 tabs.

Interaction of derived polymers from pyrrole with biocompatible solutions; Interaccion de polimeros derivados de pirrol con soluciones biocompatibles

Energy Technology Data Exchange (ETDEWEB)

Lopez G, O. G.

2010-07-01

This work presents a study about the synthesis by plasma, the electric properties and superficial interaction of polymers derived from pyrrole doped with Iodine with potential use as bio material. Poly-pyrrole is a semiconductor and biocompatible polymer with potential application in the development of artificial muscles and implants where the electric interaction between cells and material is an important variable. The syntheses were made at 13.5 MHz in a glass tubular reactor of 1500 cm{sup 3} with electrodes of 6.5 cm diameter and stainless steel flanges. An electrode was connected to the RF terminal of the power supply that is combined with a matching coupling resistance. The monomer and dopant used in this work were pyrrole and Iodine respectively, in closed containers. They were vaporized and injected separately into the reactor at room temperature and 0.1 mbar. The vapors of the reagents mixed freely in the reactor. The synthesis time was 240 min at 40, 60, 80 and 100 W. The polymers were obtained as thin films adhered to the reactor walls. The films were washed and swollen with distilled water and removed from the reactor walls with a small spatula. The polymers were irradiated with gamma rays at 18 and 22 KGy. Due to the fact that the doses are cumulative, the final dose applied was 40 KGy. The polymers characterization was carried out by Fourier Transform Infrared Spectroscopy, thermogravimetric analysis (TGA), scanning electron microscopy, contact angle, electrical conductivity and X-ray diffraction. The analyses indicates that the polymers have very similar structure in almost the entire power range, showing C-O, C=C, C-H, O-H, N-H bonds with a predominantly amorphous structure. The TGA analyses showed that the material has 4 or 5 loses of material. The first one starts after that 115 C except for the material irradiated at 40 KGy, this one begins in 87 C, the second one is in the interval of 196 and 295 C, the third one between 311 and 500 C, and the

Fibroblast adhesion and activation onto micro-machined titanium surfaces.

Science.gov (United States)

Guillem-Marti, J; Delgado, L; Godoy-Gallardo, M; Pegueroles, M; Herrero, M; Gil, F J

2013-07-01

Surface modifications performed at the neck of dental implants, in the manner of micro-grooved surfaces, can reduce fibrous tissue encapsulation and prevent bacterial colonization, thereby improving fibrointegration and the formation of a biological seal. However, the applied procedures are technically complex and/or time consuming methods. The aim of this study was to analyse the fibroblast behaviour on modified titanium surfaces obtained, applying a simple and low-cost method. An array of titanium surfaces was obtained using a commercial computerized numerical control lathe, modifying the feed rate and the cutting depth. To elucidate the potential ability of the generated surfaces to activate connective tissue cells, a thorough gene (by real time - qPCR) and protein (by western blot or zymography) expression and cellular response characterization (cell morphology, cell adhesion and cell activation by secreting extracellular matrix (ECM) components and their enzyme regulators) was performed. Micro-grooved surfaces have statistically significant differences in the groove's width (approximately 10, 50 and 100 μm) depending on the applied advancing fixed speed. Field emission scanning electron microscopy images showed that fibroblasts oriented along the generated grooves, but they were only entirely accommodated on the wider grooves (≥50 μm). Micro-grooved surfaces exhibited an earlier cell attachment and activation, as seen by collagen Iα1 and fibronectin deposition and activation of ECM remodelling enzymes, compared with the other surfaces. However, fibroblasts could remain in an activated state on narrower surfaces (fibrotic response. © 2012 John Wiley & Sons A/S.

Surface and Adsorption Properties of Activated Carbon Fabric Prepared from Cellulosic Polymer: Mixed Activation Method

Energy Technology Data Exchange (ETDEWEB)

Bhati, Surendra; Mahur, J. S.; Choubey, O. N. [Barkatullah Univ., Bhopal (India); Dixit, Mahur Savita [Maulana Azad National Institute of Technology, Bhopla (India)

2013-02-15

In this study, activated carbon fabric was prepared from a cellulose-based polymer (viscose rayon) via a combination of physical and chemical activation (mixed activation) processes by means of CO{sub 2} as a gasifying agent and surface and adsorption properties were evaluated. Experiments were performed to investigate the consequence of activation temperature (750, 800, 850 and 925 .deg. C), activation time (15, 30, 45 and 60 minutes) and CO{sub 2} flow rate (100, 200, 300 and 400 mL/min) on the surface and adsorption properties of ACF. The nitrogen adsorption isotherm at 77 K was measured and used for the determination of surface area, total pore volume, micropore volume, mesopore volume and pore size distribution using BET, t-plot, DR, BJH and DFT methods, respectively. It was observed that BET surface area and TPV increase with rising activation temperature and time due to the formation of new pores and the alteration of micropores into mesopores. It was also found that activation temperature dominantly affects the surface properties of ACF. The adsorption of iodine and CCl{sub 4} onto ACF was investigated and both were found to correlate with surface area.

Surface and Adsorption Properties of Activated Carbon Fabric Prepared from Cellulosic Polymer: Mixed Activation Method

International Nuclear Information System (INIS)

Bhati, Surendra; Mahur, J. S.; Choubey, O. N.; Dixit, Mahur Savita

2013-01-01

In this study, activated carbon fabric was prepared from a cellulose-based polymer (viscose rayon) via a combination of physical and chemical activation (mixed activation) processes by means of CO 2 as a gasifying agent and surface and adsorption properties were evaluated. Experiments were performed to investigate the consequence of activation temperature (750, 800, 850 and 925 .deg. C), activation time (15, 30, 45 and 60 minutes) and CO 2 flow rate (100, 200, 300 and 400 mL/min) on the surface and adsorption properties of ACF. The nitrogen adsorption isotherm at 77 K was measured and used for the determination of surface area, total pore volume, micropore volume, mesopore volume and pore size distribution using BET, t-plot, DR, BJH and DFT methods, respectively. It was observed that BET surface area and TPV increase with rising activation temperature and time due to the formation of new pores and the alteration of micropores into mesopores. It was also found that activation temperature dominantly affects the surface properties of ACF. The adsorption of iodine and CCl 4 onto ACF was investigated and both were found to correlate with surface area

Activity-Dependent Regulation of Surface Glucose Transporter-3

OpenAIRE

Ferreira, Jainne M.; Burnett, Arthur L.; Rameau, Gerald A.

2011-01-01

Glucose transporter 3 (GLUT3) is the main facilitative glucose transporter in neurons. Glucose provides neurons with a critical energy source for neuronal activity. However, the mechanism by which neuronal activity controls glucose influx via GLUT3 is unknown. We investigated the influence of synaptic stimulation on GLUT3 surface expression and glucose import in primary cultured cortical and hippocampal neurons. Synaptic activity increased surface expression of GLUT3 leading to an elevation o...

Surface active properties of lipid nanocapsules.

Directory of Open Access Journals (Sweden)

Celia R A Mouzouvi

Full Text Available Lipid nanocapsules (LNCs are biomimetic nanocarriers used for the encapsulation of a broad variety of active ingredients. Similar to surface active compounds, LNCs contain both hydrophilic and hydrophobic parts in their structure. Moreover, the components of LNCs, macrogol 15 hydroxystearate (MHS and lecithin, are known for their surface active properties. Therefore, the aim of this paper was to investigate the capability of the LNCs to decrease surface tension using two techniques: drop tensiometry and the Wilhelmy plate method. LNCs with diameters ranging from 30 to 100 nm were successfully obtained using a phase inversion technique. The LNCs' properties, such as size and zeta potential, depend on the composition. LNCs exhibit a lower limiting surface tension compared to MHS (34.8-35.0 mN/m and 37.7-38.8 mN/m, respectively, as confirmed by both drop tensiometry and the Wilhelmy plate method. LNCs have exhibited a saturated interfacial concentration (SIC that was 10-fold higher than the critical micellar concentration (CMC of MHS or the SIC of binary and ternary mixtures of LNC ingredients. The SIC of the LNC formulations depended on the mass mixing ratio of the MHS/triglycerides but not on the presence of lecithin. The CMC/SIC values measured by the Wilhelmy plate method were higher than those obtained using drop tensiometry because of the longer duration of the tensiometry measurement. In conclusion, the surfactant-like properties of the LNCs offer new possibilities for medical and pharmaceutical applications.

An approach towards azafuranomycin analogs by gold-catalyzed cycloisomerization of allenes: synthesis of (αS,2R-(2,5-dihydro-1H-pyrrol-2-ylglycine

Directory of Open Access Journals (Sweden)

Jörg Erdsack

2013-09-01

Full Text Available The synthesis of (αS,2R-(2,5-dihydro-1H-pyrrol-2-ylglycine (22, normethylazafuranomycin by the gold-catalyzed cycloisomerization of α-aminoallene 17 is described. The target molecule was synthesized in 13 linear steps from Cbz-protected Garner aldehyde (R-2 in an overall yield of 2.4%. The approach was first examined in model studies, which afforded the alkylated azafuranomycin derivative 13a in 2.9% yield over 12 steps.

Active micromixer using surface acoustic wave streaming

Science.gov (United States)

Branch,; Darren W. , Meyer; Grant D. , Craighead; Harold, G [Ithaca, NY

2011-05-17

An active micromixer uses a surface acoustic wave, preferably a Rayleigh wave, propagating on a piezoelectric substrate to induce acoustic streaming in a fluid in a microfluidic channel. The surface acoustic wave can be generated by applying an RF excitation signal to at least one interdigital transducer on the piezoelectric substrate. The active micromixer can rapidly mix quiescent fluids or laminar streams in low Reynolds number flows. The active micromixer has no moving parts (other than the SAW transducer) and is, therefore, more reliable, less damaging to sensitive fluids, and less susceptible to fouling and channel clogging than other types of active and passive micromixers. The active micromixer is adaptable to a wide range of geometries, can be easily fabricated, and can be integrated in a microfluidic system, reducing dead volume. Finally, the active micromixer has on-demand on/off mixing capability and can be operated at low power.

Active colloidal propulsion over a crystalline surface

Science.gov (United States)

Choudhury, Udit; Straube, Arthur V.; Fischer, Peer; Gibbs, John G.; Höfling, Felix

2017-12-01

We study both experimentally and theoretically the dynamics of chemically self-propelled Janus colloids moving atop a two-dimensional crystalline surface. The surface is a hexagonally close-packed monolayer of colloidal particles of the same size as the mobile one. The dynamics of the self-propelled colloid reflects the competition between hindered diffusion due to the periodic surface and enhanced diffusion due to active motion. Which contribution dominates depends on the propulsion strength, which can be systematically tuned by changing the concentration of a chemical fuel. The mean-square displacements (MSDs) obtained from the experiment exhibit enhanced diffusion at long lag times. Our experimental data are consistent with a Langevin model for the effectively two-dimensional translational motion of an active Brownian particle in a periodic potential, combining the confining effects of gravity and the crystalline surface with the free rotational diffusion of the colloid. Approximate analytical predictions are made for the MSD describing the crossover from free Brownian motion at short times to active diffusion at long times. The results are in semi-quantitative agreement with numerical results of a refined Langevin model that treats translational and rotational degrees of freedom on the same footing.

Surface composition of carburized tungsten trioxide and its catalytic activity

International Nuclear Information System (INIS)

Nakazawa, M.; Okamoto, H.

1985-01-01

The surface composition and electronic structure of carburized tungsten trioxide are investigated using x-ray photoelectron spectroscopy (XPS). The relationship between the surface composition and the catalytic activity for methanol electro-oxidation is clarified. The tungsten carbide concentration in the surface layer increases with the carburization time. The formation of tungsten carbide enhances the catalytic activity. On the other hand, the presence of free carbon or tungsten trioxide in the surface layer reduces the activity remarkably. It is also shown that, the higher the electronic density of states near the Fermi level, the higher the catalytic activity

The detection of intestinal spike activity on surface electroenterograms

Energy Technology Data Exchange (ETDEWEB)

Ye-Lin, Y; Garcia-Casado, J; Martinez-de-Juan, J L; Prats-Boluda, G [Instituto interuniversitario de investigacion en bioingenierIa y tecnologIa orientada al ser humano (I3BH), Universidad Politecnica de Valencia, Camino de Vera, s/n, Ed. 8E, Acceso N, 2a, planta 46022 Valencia (Spain); Ponce, J L [Department of Surgery, Hospital Universitario La Fe de Valencia, Avenida Campanar n0. 51, 46009 Valencia (Spain)], E-mail: yiye@eln.upv.es, E-mail: jgarciac@eln.upv.es, E-mail: jlmartinez@eln.upv.es, E-mail: geprabo@eln.upv.es, E-mail: drjlponce@ono.com

2010-02-07

Myoelectrical recording could provide an alternative technique for assessing intestinal motility, which is a topic of great interest in gastroenterology since many gastrointestinal disorders are associated with intestinal dysmotility. The pacemaker activity (slow wave, SW) of the electroenterogram (EEnG) has been detected in abdominal surface recordings, although the activity related to bowel contractions (spike bursts, SB) has to date only been detected in experimental models with artificially favored electrical conductivity. The aim of the present work was to assess the possibility of detecting SB activity in abdominal surface recordings under physiological conditions. For this purpose, 11 recording sessions of simultaneous internal and external myolectrical signals were conducted on conscious dogs. Signal analysis was carried out in the spectral domain. The results show that in periods of intestinal contractile activity, high-frequency components of EEnG signals can be detected on the abdominal surface in addition to SW activity. The energy between 2 and 20 Hz of the surface myoelectrical recording presented good correlation with the internal intestinal motility index (0.64 {+-} 0.10 for channel 1 and 0.57 {+-} 0.11 for channel 2). This suggests that SB activity can also be detected in canine surface EEnG recording.

The detection of intestinal spike activity on surface electroenterograms

International Nuclear Information System (INIS)

Ye-Lin, Y; Garcia-Casado, J; Martinez-de-Juan, J L; Prats-Boluda, G; Ponce, J L

2010-01-01

Myoelectrical recording could provide an alternative technique for assessing intestinal motility, which is a topic of great interest in gastroenterology since many gastrointestinal disorders are associated with intestinal dysmotility. The pacemaker activity (slow wave, SW) of the electroenterogram (EEnG) has been detected in abdominal surface recordings, although the activity related to bowel contractions (spike bursts, SB) has to date only been detected in experimental models with artificially favored electrical conductivity. The aim of the present work was to assess the possibility of detecting SB activity in abdominal surface recordings under physiological conditions. For this purpose, 11 recording sessions of simultaneous internal and external myolectrical signals were conducted on conscious dogs. Signal analysis was carried out in the spectral domain. The results show that in periods of intestinal contractile activity, high-frequency components of EEnG signals can be detected on the abdominal surface in addition to SW activity. The energy between 2 and 20 Hz of the surface myoelectrical recording presented good correlation with the internal intestinal motility index (0.64 ± 0.10 for channel 1 and 0.57 ± 0.11 for channel 2). This suggests that SB activity can also be detected in canine surface EEnG recording.

Exotic high activity surface patterns in PtAu nanoclusters

KAUST Repository

Mokkath, Junais Habeeb; Schwingenschlö gl, Udo

2013-01-01

of the truncated octahedron cluster motif. Exotic surface patterns are obtained particularly for Pt-rich compositions, where Pt atoms are being surrounded by Au atoms. These surface arrangements boost the catalytic activity by creating a large number of active

Nano-silver mediated polymerization of pyrrole: synthesis and gas sensing properties of polypyrrole (PPy)/Ag nano-composite.

Science.gov (United States)

Kate, Kunal H; Damkale, Shubhangi R; Khanna, P K; Jain, G H

2011-09-01

Thermal polymerization of pyrrole was performed using silver nitrate as source of silver ions followed by its conversion to Polypyrrole (PPy)/Ag nano-comoposites without using any external oxidizing agent or solvent. The formation of PPy was monitored by UV-Visible absorption spectroscopy showing a band at approximately 464 nm. XRD measurement confirmed characteristic peaks for face centered cubic (fcc) silver and presence of PPy at 2 theta of approximately 23 degrees suggesting the formation of PPy/Ag nanocomposite. Transmission electron microscopy (TEM) images showed non-aggregated spherical Ag nano-particles of about 5-10 nm. PPy/Ag thick film acts as a NH3 sensor at 100 degrees C, a H2S sensor at 250 degrees C and CO2 sensor at 350 degrees C. The thick films showed capability to recognize various gases at different operating temperature.

Hemispherand-Strapped Calix[4]pyrrole: An Ion-pair Receptor for the Recognition and Extraction of Lithium Nitrite.

Science.gov (United States)

He, Qing; Zhang, Zhan; Brewster, James T; Lynch, Vincent M; Kim, Sung Kuk; Sessler, Jonathan L

2016-08-10

The hemispherand-strapped calix[4]pyrrole (1) acts as an ion pair receptor that exhibits selectivity for lithium salts. In organic media (CD2Cl2 and CD3OD, v/v, 9:1), receptor 1 binds LiCl with high preference relative to NaCl, KCl, and RbCl. DFT calculations provided support for the observed selectivity. Single crystal structures of five different lithium ion-pair complexes of 1 were obtained. In the case of LiCl, a single bridging water molecule between the lithium cation and chloride anion was observed, while tight contact ion pairs were observed in the case of the LiBr, LiI, LiNO3, and LiNO2 salts. Receptor 1 proved effective as an extractant for LiNO2 under both model solid-liquid and liquid-liquid extraction conditions.

Redox and catalytic properties of new polypyrrole modified electrodes functionalized by [Ru(bpea)(bpy)H{sub 2}O]{sup 2+} complexes; bpea=N,N'-bis(2-pyridylmethyl)ethylamine, bpy=2,2'-bipyridine

Energy Technology Data Exchange (ETDEWEB)

Rodriguez, Montserrat; Romero, Isabel; Sens, Cristina; Llobet, Antoni; Deronzier, Alain

2003-04-05

New ruthenium(II) complexes containing one or two pyrrole-functionalized polypyridylic ligands have been prepared in order to study their electrochemical behaviour in heterogeneous phase, after anodic polymerization from CH{sub 2}Cl{sub 2} solution on an electrode surface. Complexes containing one pyrrole unit have general formula [Ru(bpea-pyr)(bpy)(L)]{sup 2+} (bpea-pyr=N-[3-bis(2-pyridylmethyl)aminopropyl]pyrrole, bpy=2,2'-bipyridine, L=Cl, complex 3, or L=H{sub 2}O, complex 1), whereas compounds having two pyrrole units correspond to [Ru(bpea-pyr)(bpy-pyr)(L)]{sup 2+} (bpy-pyr=4-methyl-4'-pyrrolylbutyl-2,2'-bipyridine, L=Cl, complex 4, or L=H{sub 2}O, complex 2). Upon oxidative polymerization, all complexes form highly stable polypyrrolic films on a graphite disk electrode surface. An electrode modified with complex 2 polypyrrole coating film, C/poly-2, has been tested as heterogeneous catalyst for the oxidation of benzyl alcohol, showing a remarkably high efficiency and notably improving the results obtained with analogous complexes in homogeneous phase.

Effect of Heat Treatment on the Surface Properties of Activated Carbons

Directory of Open Access Journals (Sweden)

Meriem Belhachemi

2011-01-01

Full Text Available This work reports the effect of heat treatment on the porosity and surface chemistry of two series of activated carbons prepared from a local agricultural biomass material, date pits, by physical activation with carbon dioxide and steam. Both series samples were oxidized with nitric acid and subsequently heat treated under N2 at 973 K in order to study the effect of these treatments in porosity and surface functional groups of activated carbons. When the activated carbons were heat treated after oxidation the surface area and the pore volume increase for both activated carbons prepared by CO2 and steam activations. However the amount of surface oxygen complexes decreases, the samples keep the most stable oxygen surface groups evolved as CO by temperature-programmed desorption experiments at high temperature. The results show that date pits can be used as precursors to produce activated carbons with a well developed porosity and tailored oxygen surface groups.

Vinyl ethers, containing isothiocyanate group. 12. Reaction of 2-vinyloxyethylisothiocyanate with metallated ethoxyethene, methoxyalline and 2-alkynes: 2,3-disubstituted N-(2-vinyloxyethyl) pyrroles and 6-(vinyloxymethyl)-5,6-dihydropyridines

International Nuclear Information System (INIS)

Nedolya, N.A.; Brandsma, L.; Zinov'eva, V.P.; Trofimov, B.A.

1997-01-01

New route of synthesis of 1,2,3-trisubstituted pyrroles and 2,3,6-trisubstituted 5,6-dyhydropyridines by the reaction of lithiated alkoxyallenes and 2-alkynes with 2-vinyloxyethylisothiocyanate is found. It is shown that key intermediates are 1,3,4-azatrienes. Reaction of metallized ethoxyethene with 2-vinyloxyethyisothiocyanate (after intermediate alkylation) results in 1-(2-vinyloxyethyl)-1,3-azadiene

Effects of altered platelet number on pulmonary hypertension and platelet sequestration in monocrotaline pyrrole-treated rats

International Nuclear Information System (INIS)

White, S.M.; Wagner, J.G.; Roth, R.A.

1989-01-01

To study the role of platelets in monocrotaline pyrrole (MCTP)-induced pulmonary hypertension, pulmonary sequestration of 111In-labeled platelets in rats treated with MCTP and anti-rat platelet serum (PAS) was examined. Lung injury from a single, intravenous injection of MCTP (3.5 mg/kg) at Day 8 was evident as elevated lung weight and lavage fluid protein and lactate dehydrogenase activity. Additionally, right ventricular hypertrophy and elevated pulmonary arterial pressures (PAP) occurred. Treatment with PAS on Days 6-8 did not affect the lung injury but resulted in an attenuation of the pulmonary hypertensive response. Pulmonary platelet sequestration was also decreased in PAS-treated rats, yet the sequestration in the lungs of MCTP-treated rats that received PAS was significantly higher than that in the lungs of N,N-dimethylformamide (DMF) controls. MCTP-treated rats receiving control serum (CS) tended to sequester more 111In-labeled platelets than respective DMF controls, but this was not statistically significant. Blood platelet half-life was unaltered in rats receiving CS. When rats were treated similarly with MCTP and PAS and were killed at 18 days, the attenuation of the pulmonary hypertensive response previously described was not observed, and lung injury was more extensive than when CS was given. Apparently, platelet depletion delayed the development of the pulmonary hypertensive response. Supranormal platelet numbers produced by splenectomy did not affect MCTP-induced lung injury or the elevation in PAP. These results support the hypothesis that the development of MCTP-induced pulmonary hypertension is mediated in part by platelets

Effect of surface wettability caused by radiation induced surface activation on leidenfrost condition

International Nuclear Information System (INIS)

Takamasa, T.; Hazuku, T.; Tamura, N.; Okamoto, K.; Mishima, K.; Furuya, M.

2003-01-01

Improving the limit of boiling heat transfer or critical heat flux requires that the cooling liquid can contact the heating surface, or a high-wettability, highly hydrophilic heating surface, even if a vapor bubble layer is generated on the surface. From this basis, we investigated surface wettability and Leidenfrost condition using metal oxides irradiated by γ-rays. In our previous study, contact angle, an indicator of macroscopic wettability, of a water droplet on metal oxide at room temperature was measured by image processing of the images obtained by a CCD video camera. The results showed that the surface wettability on metal oxide pieces of titanium, Zircaloy No. 4, SUS-304, and copper was improved significantly by the Radiation Induced Surface Activation (RISA) phenomenon. To delineate the effect of Radiation Induced Surface Activation (RISA) on heat transferring phenomena, the Leidenfrost condition and quenching of metal oxides irradiated by γ-rays were investigated. In the Leidenfrost experiment, when the temperature of the heating surface reached the wetting limit temperature, water-solid contact vanished because a stable vapor film existed between the droplet and the metal surface; i.e., a Leidenfrost condition obtained. The wetting limit temperature increased with integrated irradiation dose. After irradiation, the wet length and the duration of contact increased, and the contact angle decreased. In the quenching test, high surface wettability, or a highly hydrophilic condition, of a simulated fuel rod made of SUS was achieved, and the quenching velocities were increased up to 20-30% after 300 kGy 60Co γ-ray irradiation

Effect of surface wettability caused by radiation induced surface activation on leidenfrost condition

Energy Technology Data Exchange (ETDEWEB)

Takamasa, T.; Hazuku, T.; Tamura, N.; Okamoto, K. [Tokyo Univ., Tokyo (Japan); Mishima, K. [Kyoto Univ., Kyoto (Japan); Furuya, M. [Central Research Institute of Electric Power Industry, Tokyo (Japan)

2003-07-01

Improving the limit of boiling heat transfer or critical heat flux requires that the cooling liquid can contact the heating surface, or a high-wettability, highly hydrophilic heating surface, even if a vapor bubble layer is generated on the surface. From this basis, we investigated surface wettability and Leidenfrost condition using metal oxides irradiated by {gamma}-rays. In our previous study, contact angle, an indicator of macroscopic wettability, of a water droplet on metal oxide at room temperature was measured by image processing of the images obtained by a CCD video camera. The results showed that the surface wettability on metal oxide pieces of titanium, Zircaloy No. 4, SUS-304, and copper was improved significantly by the Radiation Induced Surface Activation (RISA) phenomenon. To delineate the effect of Radiation Induced Surface Activation (RISA) on heat transferring phenomena, the Leidenfrost condition and quenching of metal oxides irradiated by {gamma}-rays were investigated. In the Leidenfrost experiment, when the temperature of the heating surface reached the wetting limit temperature, water-solid contact vanished because a stable vapor film existed between the droplet and the metal surface; i.e., a Leidenfrost condition obtained. The wetting limit temperature increased with integrated irradiation dose. After irradiation, the wet length and the duration of contact increased, and the contact angle decreased. In the quenching test, high surface wettability, or a highly hydrophilic condition, of a simulated fuel rod made of SUS was achieved, and the quenching velocities were increased up to 20-30% after 300 kGy 60Co {gamma}-ray irradiation.

Excess L-arginine restores endothelium-dependent relaxation impaired by monocrotaline pyrrole

International Nuclear Information System (INIS)

Cheng Wei; Oike, Masahiro; Hirakawa, Masakazu; Ohnaka, Keizo; Koyama, Tetsuya; Ito, Yushi

2005-01-01

The pyrrolizidine alkaloid plant toxin monocrotaline pyrrole (MCTP) causes pulmonary hypertension in experimental animals. The present study aimed to examine the effects of MCTP on the endothelium-dependent relaxation. We constructed an in vitro disease model of pulmonary hypertension by overlaying MCTP-treated bovine pulmonary artery endothelial cells (CPAEs) onto pulmonary artery smooth muscle cell-embedded collagen gel lattice. Acetylcholine (Ach) induced a relaxation of the control CPAEs-overlaid gels that were pre-contracted with noradrenaline, and the relaxation was inhibited by L-NAME, an inhibitor of NO synthase (NOS). In contrast, when MCTP-treated CPAEs were overlaid, the pre-contracted gels did not show a relaxation in response to Ach in the presence of 0.5 mM L-arginine. Expression of endothelial NOS protein, Ach-induced Ca 2+ transients and cellular uptake of L-[ 3 H]arginine were significantly smaller in MCTP-treated CPAEs than in control cells, indicating that these changes were responsible for the impaired NO production in MCTP-treated CPAEs. Since cellular uptake of L-[ 3 H]arginine linearly increased according to its extracellular concentration, we hypothesized that the excess concentration of extracellular L-arginine might restore NO production in MCTP-treated CPAEs. As expected, in the presence of 10 mM L-arginine, Ach showed a relaxation of the MCTP-treated CPAEs-overlaid gels. These results indicate that the impaired NO production in damaged endothelial cells can be reversed by supplying excess L-arginine

Response surface optimisation for activation of bentonite with microwave irradiation

Directory of Open Access Journals (Sweden)

Rožić Ljiljana S.

2011-01-01

Full Text Available In this study, the statistical design of the experimental method was applied on the acid activation process of bentonite with microwave irradiation. The influence of activation parameters (time, acid normality and microwave heating power on the selected process response of the activated bentonite samples was studied. The specific surface area was chosen for the process response, because the chemical, surface and structural properties of the activated clay determine and limit its potential applications. The relationship of various process parameters with the specific surface area of bentonite was examined. A mathematical model was developed using a second-order response surface model (RSM with a central composite design incorporating the above mentioned process parameters. The mathematical model developed helped in predicting the variation in specific surface area of activated bentonite with time (5-21 min, acid normality (2-7 N and microwave heating power (63-172 W. The calculated regression models were found to be statistically significant at the required range and presented little variability. Furthermore, high values of R2 (0.957 and R2 (adjusted (0.914 indicate a high dependence and correlation between the observed and the predicted values of the response. These high values also indicate that about 96% of the result of the total variation can be explained by this model. In addition, the model shows that increasing the time and acid normality improves the textural properties of bentonites, resulting in increased specific surface area. This model also can be useful for setting an optimum value of the activation parameters for achieving the maximum specific surface area. An optimum specific surface area of 142 m2g-1 was achieved with an acid normality of 5.2 N, activation time of 7.38 min and microwave power of 117 W. Acid activation of bentonite was found to occur faster with microwave irradiation than with conventional heating. Microwave

Surface and interface electronic structure: Three year activity report

International Nuclear Information System (INIS)

Kevan, S.D.

1992-01-01

The 3-year activity report covers surface structure and phonon anomalies (surface reconstruction on W(001) and Mo(001), adsorbate lateral ordering, surface Fermi contours and phonon anomalies on Pt(111) and Pd(001)), adsorbate vibrational damping, charge transfer in momentum space: W(011)-K, surface states and resonances (relativistic effects ampersand computations, surface resonances)

Surface activity, lipid profiles and their implications in cervical cancer.

Directory of Open Access Journals (Sweden)

Preetha A

2005-01-01

Full Text Available Background: The profiles of lipids in normal and cancerous tissues may differ revealing information about cancer development and progression. Lipids being surface active, changes in lipid profiles can manifest as altered surface activity profiles. Langmuir monolayers offer a convenient model for evaluating surface activity of biological membranes. Aims: The aims of this study were to quantify phospholipids and their effects on surface activity of normal and cancerous human cervical tissues as well as to evaluate the role of phosphatidylcholine (PC and sphingomyelin (SM in cervical cancer using Langmuir monolayers. Methods and Materials: Lipid quantification was done using thin layer chromatography and phosphorus assay. Surface activity was evaluated using Langmuir monolayers. Monolayers were formed on the surface of deionized water by spreading tissue organic phase corresponding to 1 mg of tissue and studying their surface pressure-area isotherms at body temperature. The PC and SM contents of cancerous human cervical tissues were higher than those of the normal human cervical tissues. Role of PC and SM were evaluated by adding varying amounts of these lipids to normal cervical pooled organic phase. Statistical analysis: Student′s t-test (p < 0.05 and one-way analysis of variance (ANOVA was used. Results: Our results reveals that the phosphatidylglycerol level in cancerous cervical tissue was nearly five folds higher than that in normal cervical tissue. Also PC and sphingomyelin SM were found to be the major phospholipid components in cancerous and normal cervical tissues respectively. The addition of either 1.5 µg DPPC or 0.5 µg SM /mg of tissue to the normal organic phase changed its surface activity profile to that of the cancerous tissues. Statistically significant surface activity parameters showed that PC and SM have remarkable roles in shifting the normal cervical lipophilic surface activity towards that of cancerous lipophilic

Role of nitrogen in pore development in activated carbon prepared by potassium carbonate activation of lignin

Energy Technology Data Exchange (ETDEWEB)

Tsubouchi, Naoto, E-mail: tsubon@eng.hokudai.ac.jp; Nishio, Megumi; Mochizuki, Yuuki

2016-05-15

Highlights: • Activated carbon prepared from a lignin/urea/K{sub 2}CO{sub 3} mixture provides a high specific surface area and a large pore volume. • Part of the urea nitrogen present in the mixture is retained as heterocyclic nitrogen in the solid phase after activation/carbonization. • Pore development is thought to proceed through interactions between K-species and C–N forms. - Abstract: The present work focuses on the role of nitrogen in the development of pores in activated carbon produced from lignin by K{sub 2}CO{sub 3} activation, employing a fixed bed reactor under a high-purity He stream at temperatures of 500–900 °C. The specific surface area and pore volume obtained by activation of lignin alone are 230 m{sup 2}/g and 0.13 cm{sup 3}/g at 800 °C, and 540 m{sup 2}/g and 0.31 cm{sup 3}/g at 900 °C, respectively. Activation of a mixture of lignin and urea provides a significant increase in the surface area and volume, respectively reaching 3300–3400 m{sup 2}/g and 2.0–2.3 cm{sup 3}/g after holding at 800–900 °C for 1 h. Heating a lignin/urea/K{sub 2}CO{sub 3} mixture leads to a significant decrease in the yield of released N-containing gases compared to the results for urea alone and a lignin/urea mixture, and most of the nitrogen in the urea is retained in the solid phase. X-ray photoelectron spectroscopy and X-ray diffraction analyses clearly show that part of the remaining nitrogen is present in heterocyclic structures (for example, pyridinic and pyrrolic nitrogen), and the rest is contained as KOCN at ≤600 °C and as KCN at ≥700 °C, such that the latter two compounds can be almost completely removed by water washing. The fate of nitrogen during heating of lignin/urea/K{sub 2}CO{sub 3} and role of nitrogen in pore development in activated carbon are discussed on the basis of the results mentioned above.

Reinforcement of a porous collagen scaffold with surface-activated PLA fibers.

Science.gov (United States)

Liu, Xi; Huang, Changbin; Feng, Yujie; Liang, Jie; Fan, Yujiang; Gu, Zhongwei; Zhang, Xingdong

2010-01-01

A hybrid porous collagen scaffold mechanically reinforced with surface-activated poly(lactic acid) (PLA) fiber was prepared. PLA fibers, 20 mum in diameter and 1 mm in length, were aminolyzed with hexanediamine to introduce free amino groups on the surfaces. After the amino groups were transferred to aldehyde groups by treatment with glutaraldehyde, different amounts (1.5, 3, 5 and 8 mg) of surface-activated PLA fibers were homogeneously mixed with 2 ml type-I collagen solution (pH 2.8, 0.6 wt%). This mixture solution was then freeze-dried and cross-linked to obtain collagen sponges with surface-activated PLA fiber. Scanning electron microscopy observation indicated that the collagen sponges had a highly interconnected porous structure with an average pore size of 170 mum, irrespective of PLA fiber incorporation. The dispersion of surface-activated PLA fibers was homogeneous in collagen sponge, in contrast to unactivated PLA fibers. The compression modulus test results showed that, compared with unactivated PLA fibers, the surface-activated PLA fibers enhanced the resistance of collagen sponge to compression more significantly. Cytotoxicity assay by MTT test showed no cytotoxicity of these collagen sponges. L929 mouse fibroblast cell-culture studies in vitro revealed that the number of L929 cells attached to the collagen sponge with surface-activated PLA fibers, both 6 h and 24 h after seeding, was higher than that in pure collagen sponge and sponge with unactivated PLA fibers. In addition, a better distribution of cells infiltrated in collagen sponge with surface-activated PLA fibers was observed by histological staining. These results indicated that the collagen sponge reinforced with surface-activated PLA fibers is a promising biocompatible scaffold for tissue engineering.

Technical activities, 1990: Surface Science Division

International Nuclear Information System (INIS)

Powell, C.J.

1991-05-01

The report summarizes technical activities and accomplishments of the NIST Surface Science Division during Fiscal Year 1990. Overviews are presented of the Division and of its three constituent groups: Surface Dynamical Processes, Thin Films and Interfaces, and Surface Spectroscopies and Standards. These overviews are followed by reports of selected technical accomplishments during the year. A summary is given of Division outputs and interactions that includes lists of publications, talks, committee assignments, seminars (including both Division seminars and Interface Science seminars arranged through the Division), conferences organized, and a standard reference material certified. Finally, lists are given of Division staff and of guest scientists who have worked in the Division during the past year

Active surface system for the new Sardinia Radiotelescope

Science.gov (United States)

Orfei, Alessandro; Morsiani, Marco; Zacchiroli, Giampaolo; Maccaferri, Giuseppe; Roda, Juri; Fiocchi, Franco

2004-09-01

In this paper we'll describe the active surface system that will be provided on the new Italian radiotelescope being in the phase of erection in the Sardinia Island. SRT (Sardinia Radiotelescope) will be a 64m shaped dish working up to 100GHz by exploiting the active surface facility designed by the authors. This facility will overcome the effects of gravity deformations on the antenna gain and will also be used to re-shape in a parabolic form the primary mirror, in order to avoid large phase error contribution on the antenna gain for the highest frequencies placed on the primary focus. Together with the description of the SRT system, a wide overview will be given regarding our previous installation of an active surface system, that can be seen like a prototype for SRT, mounted on the 32m dish of the Noto antenna.

Emission and absorption of light in poly pyrrole synthesized by plasma; Emision y absorcion de luz en polipirrol sintetizado por plasma

Energy Technology Data Exchange (ETDEWEB)

Enriquez, M.A.; Colin, E.; Olayo, M.G.; Cruz, G.J.; Ordonez, E. [ININ, A.P. 18-1027, 11801 Mexico D.F. (Mexico); Benavides, R. [Departamento de Procesos de Transformacion, CIQA, Blvd. Enrique Reyna 140, Saltillo, Coahuila (Mexico); Morales, J.; Olayo, R. [UAM-I, Apdo. Postal 55-534, Iztapalapa, D.F. (Mexico)]. e-mail: gcc@nuclear.inin.mx

2007-07-01

The poly pyrrole structure (PPy) consists of heterocyclic rings with conjugation that it depends on the intensity of the electric field applied during the synthesis, and its luminescence is related with the {pi}-{pi}{sup *} transitions of that conjugation. To irradiate with light of different wavelengths, the results indicate that the polymer absorbs in the interval from 290 to 700 nm and it emits between 450 and 470 nm. The basal conductivity of the polymers, without electromagnetic excitation, it was measured in 10{sup -15} S/cm, however, to interact with visible light it is increased approximately 10 times and when excite with UV light it is increased up to 3 magnitude orders. (Author)

Nitrogen Doped Ordered Mesoporous Carbon as Support of PtRu Nanoparticles for Methanol Electro-Oxidation

Directory of Open Access Journals (Sweden)

David Sebastián

2018-04-01

Full Text Available The low oxidation kinetics of alcohols and the need for expensive platinum group metals are still some of the main drawbacks for the commercialization of energy efficient direct alcohol fuel cells. In this work, we investigate the influence of nitrogen doping of ordered mesoporous carbon (CMK as support on the electrochemical activity of PtRu nanoparticles. Nitrogen doping procedures involve the utilization of pyrrole as both nitrogen and carbon precursor by means of a templating method using mesoporous silica. This method allows obtaining carbon supports with up to 14 wt. % nitrogen, with an effective introduction of pyridinic, pyrrolic and quaternary nitrogen. PtRu nanoparticles were deposited by sodium formate reduction method. The presence of nitrogen mainly influences the Pt:Ru atomic ratio at the near surface, passing from 50:50 on the bare (un-doped CMK to 70:30 for the N-doped CMK catalyst. The electroactivity towards the methanol oxidation reaction (MOR was evaluated in acid and alkaline electrolytes. The presence of nitrogen in the support favors a faster oxidation of methanol due to the enrichment of Pt at the near surface together with an increase of the intrinsic activity of PtRu nanoparticles.

Active sites of the cytochrome p450cam (CYP101) F87W and F87A mutants. Evidence for significant structural reorganization without alteration of catalytic regiospecificity.

Science.gov (United States)

Tuck, S F; Graham-Lorence, S; Peterson, J A; Ortiz de Montellano, P R

1993-01-05

Ferricyanide oxidation of the aryl-iron complexes formed by the reaction of cytochrome P450 enzymes with arylhydrazines causes in situ migration of the aryl group from the iron to the porphyrin nitrogen atoms. The regiochemistry of this migration, defined by the ratio of the four possible N-arylprotoporphyrin IX isomers, provides a method for mapping the topologies of cytochrome P450 active sites. The method has been validated by using it to examine the active site of cytochrome P450cam (CYP101), for which a crystal structure is available. In agreement with the crystal structure, reaction with phenylhydrazine gives a 5:25:70 ratio of the NA:NC:ND (subscript indicates pyrrole ring) N-phenylprotoporphyrin IX isomers. Naphthylhydrazine, however, yields exclusively the NC regioisomer and 4-(phenyl)phenylhydrazine the NA:NC:ND isomers in a 14:40:46 ratio. These isomer ratio differences are readily explained by topological differences between the upper and lower reaches of the active site. Having validated the aryl-iron shift as a topological probe, we used it to investigate the structural changes caused by mutation of Phe-87, a residue that provides the ceiling over pyrrole ring D in the crystal structure of cytochrome P450cam. Mutation of Phe-87 to a tryptophan causes no detectable change in the regiochemistry of camphor hydroxylation and only minor changes in the N-aryl isomer ratios. However, mutation of Phe-87 to an alanine, which was expected to open up the region above pyrrole ring D, severely decreased the proportion of the ND in favor of the NA isomer. Less rather than more space is therefore available over pyrrole ring D in the F87A mutant despite the fact that the regiochemistry of camphor hydroxylation remains unchanged. These results provide evidence for significant structural reorganization in the upper regions of the substrate binding site without alteration of the camphor hydroxylation regiospecificity in the F87A mutant.

Critical reflection activation analysis - a new near-surface probe

International Nuclear Information System (INIS)

Gunn, J.M.F.; Trohidou, K.N.

1988-09-01

We propose a new surface analytic technique, Critical Reflection Activation Analysis (CRAA). This technique allows accurate depth profiling of impurities ≤ 100A beneath a surface. The depth profile of the impurity is simply related to the induced activity as a function of the angle of reflection. We argue that the technique is practical and estimate its accuracy. (author)

Ordering effects in benzo[1,2-b:4,5-b']difuran-thieno[3,4-c]pyrrole-4,6- dione polymers with >7% solar cell efficiency

KAUST Repository

Warnan, Julien

2014-05-15

Benzo[1,2-b:4,5-b\\']difuran-thieno[3,4-c]pyrrole-4,6-dione (PBDFTPD) polymers prepared by microwave-assisted synthesis can achieve power conversion efficiencies (PCEs) >7% in bulk-heterojunction solar cells with phenyl-C61/71-butyric acid methyl ester (PCBM). In "as-cast" PBDFTPD-based devices solution-processed without a small-molecule additive, high PCEs can be obtained in spite of the weak propensity of the polymers to self-assemble and form π-aggregates in thin films. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Surface-active biopolymers from marine bacteria for potential biotechnological applications

Directory of Open Access Journals (Sweden)

Karina Sałek

2016-03-01

Full Text Available Surface-active agents are amphiphilic chemicals that are used in almost every sector of modern industry, the bulk of which are produced by organo-chemical synthesis. Those produced from biological sources (biosurfactants and bioemulsifiers, however, have gained increasing interest in recent years due to their wide structural and functional diversity, lower toxicities and high biodegradability, compared to their chemically-synthesised counterparts. This review aims to present a general overview on surface-active agents, including their classification, where new types of these biomolecules may lay awaiting discovery, and some of the main bottlenecks for their industrial-scale production. In particular, the marine environment is highlighted as a largely untapped source for discovering new types of surface-active agents. Marine bacteria, especially those living associated with micro-algae (eukaryotic phytoplankton, are a highly promising source of polymeric surface-active agents with potential biotechnological applications. The high uronic acids content of these macromolecules has been linked to conferring them with amphiphilic qualities, and their high structural diversity and polyanionic nature endows them with the potential to exhibit a wide range of functional diversity. Production yields (e.g. by fermentation for most microbial surface-active agents have often been too low to meet the volume demands of industry, and this principally remains as the most important bottleneck for their further commercial development. However, new developments in recombinant and synthetic biology approaches can offer significant promise to alleviate this bottleneck. This review highlights a particular biotope in the marine environment that offers promise for discovering novel surface-active biomolecules, and gives a general overview on specific areas that researchers and the industry could focus work towards increasing the production yields of microbial surface-active

Synthesis and Development of Gold Polypyrrole Actuator for Underwater Application

Science.gov (United States)

Panda, S. K.; Bandopadhya, D.

2018-02-01

Electro-active polymer (EAP) such as Polypyrrole has gained much attention in the category of functional materials for fabrication of both active actuator and sensor. Particularly, PPy actuator has shown potential in fluid medium application because of high strain, large bending displacement and work density. This paper focuses on developing a low cost active actuator promising in delivering high performance in underwater environment. The proposed Au-pyrrole actuator is synthesized by adopting the layer-by-layer electrochemical polymerization technique and is fabricated as strip actuator from aqueous solution of Pyrrole and NaDBS in room temperature. In the follow-up, topographical analysis has been carried out using SEM and FESEM instruments showing surface morphology and surface integrity of chemical components of the structure. Several experiments have been conducted under DC input voltage evaluating performance effectiveness such as underwater bending displacement and tip force etc. This is observed that the actuator exhibits quite similar stress profile as of natural muscle, endowed with high modulus makes them effective in working nearly 10,000 cycles underwater environment. In addition, the bending displacement up to 5.4 mm with a low input voltage 1.3 V makes the actuator suitable for underwater micro-robotics applications.

Highly reproducible surface-enhanced Raman scattering-active Au nanostructures prepared by simple electrodeposition: origin of surface-enhanced Raman scattering activity and applications as electrochemical substrates.

Science.gov (United States)

Choi, Suhee; Ahn, Miri; Kim, Jongwon

2013-05-24

The fabrication of effective surface-enhanced Raman scattering (SERS) substrates has been the subject of intensive research because of their useful applications. In this paper, dendritic gold (Au) rod (DAR) structures prepared by simple one-step electrodeposition in a short time were examined as an effective SERS-active substrate. The SERS activity of the DAR surfaces was compared to that of other nanostructured Au surfaces with different morphologies, and its dependence on the structural variation of DAR structures was examined. These comparisonal investigations revealed that highly faceted sharp edge sites present on the DAR surfaces play a critical role in inducing a high SERS activity. The SERS enhancement factor was estimated to be greater than 10(5), and the detection limit of rhodamine 6G at DAR surfaces was 10(-8)M. The DAR surfaces exhibit excellent spot-to-spot and substrate-to-substrate SERS enhancement reproducibility, and their long-term stability is very good. It was also demonstrated that the DAR surfaces can be effectively utilized in electrochemical SERS systems, wherein a reversible SERS behavior was obtained during the cycling to cathodic potential regions. Considering the straightforward preparation of DAR substrates and the clean nature of SERS-active Au surfaces prepared in the absence of additives, we expect that DAR surfaces can be used as cost-effective SERS substrates in analytical and electrochemical applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Direct instrumental identification of catalytically active surface sites

Science.gov (United States)

Pfisterer, Jonas H. K.; Liang, Yunchang; Schneider, Oliver; Bandarenka, Aliaksandr S.

2017-09-01

The activity of heterogeneous catalysts—which are involved in some 80 per cent of processes in the chemical and energy industries—is determined by the electronic structure of specific surface sites that offer optimal binding of reaction intermediates. Directly identifying and monitoring these sites during a reaction should therefore provide insight that might aid the targeted development of heterogeneous catalysts and electrocatalysts (those that participate in electrochemical reactions) for practical applications. The invention of the scanning tunnelling microscope (STM) and the electrochemical STM promised to deliver such imaging capabilities, and both have indeed contributed greatly to our atomistic understanding of heterogeneous catalysis. But although the STM has been used to probe and initiate surface reactions, and has even enabled local measurements of reactivity in some systems, it is not generally thought to be suited to the direct identification of catalytically active surface sites under reaction conditions. Here we demonstrate, however, that common STMs can readily map the catalytic activity of surfaces with high spatial resolution: we show that by monitoring relative changes in the tunnelling current noise, active sites can be distinguished in an almost quantitative fashion according to their ability to catalyse the hydrogen-evolution reaction or the oxygen-reduction reaction. These data allow us to evaluate directly the importance and relative contribution to overall catalyst activity of different defects and sites at the boundaries between two materials. With its ability to deliver such information and its ready applicability to different systems, we anticipate that our method will aid the rational design of heterogeneous catalysts.

Characterization of poly pyrrole/montmorillonite electro polymerised onto Pt; Caracterizacao de filmes PPy/montmorilonita eletropolimerizados sobre Pt

Energy Technology Data Exchange (ETDEWEB)

Castagno, K.R.L., E-mail: katiarlc@pelotas.ifsul.edu.b [Instituto Federal Sul-rio-grandense (IFSul), RS (Brazil). Dept. de Quimica; Azambuja, D.S.; Dalmoro, V.; Mauller, R.S. [Universidade Federal do Rio Grande do Sul (UFRGS), Pelotas, RS (Brazil). Inst. de Quimica

2010-07-01

In this study films of polypyrrole/montmorillonite (PPy/MT) were electropolymerized on platinum in order to evaluate the performance of this technique in the preparation of nanocomposite materials and to determine the thermal properties and conductivity of the composites. The films were synthesized from a solution containing pyrrole, dodecylbenzene sulfonate, acid and two types of clays: montmorillonite-Na + (MT-Na) and montmorillonite-30B (MT-M). The characterization of the films we have used FT-IR, TEM, XRD, TGA, DSC and resistivity measurement by the four-point van der Pauw method. The study showed that the adopted method of exfoliation and the electropolymerization method used, allows obtaining nanocomposite materials. Analyses of FT-IR, TEM and XRD show that the clays are exfoliated in the polymer matrix. Thermal analysis of the films indicates that the addition of clay reflects an enhancement in the thermal properties of the matrix of PPy, but decreases the conductivity of the same. (author)

Sub-10 nm Platinum Nanocrystals with Size and Shape Control: Catalytic Study for Ethylene and Pyrrole Hydrogenation

Energy Technology Data Exchange (ETDEWEB)

Tsung, Chia-Kuang; Kuhn, John N.; Huang, Wenyu; Aliaga, Cesar; Hung, Ling-I; Somorjai, Gabor A.; Yang, Peidong

2009-03-02

Platinum nanocubes and nanopolyhedra with tunable size from 5 to 9 nm were synthesized by controlling the reducing rate of metal precursor ions in a one-pot polyol synthesis. A two-stage process is proposed for the simultaneous control of size and shape. In the first stage, the oxidation state of the metal ion precursors determined the nucleation rate and consequently the number of nuclei. The reaction temperature controlled the shape in the second stage by regulation of the growth kinetics. These well-defined nanocrystals were loaded into MCF-17 mesoporous silica for examination of catalytic properties. Pt loadings and dispersions of the supported catalysts were determined by elemental analysis (ICP-MS) and H2 chemisorption isotherms, respectively. Ethylene hydrogenation rates over the Pt nanocrystals were independent of both size and shape and comparable to Pt single crystals. For pyrrole hydrogenation, the nanocubes enhanced ring-opening ability and thus showed a higher selectivity to n-butylamine as compared to nanopolyhedra.

Synthesis of 1-((4-methoxyphenyl-3-alkynes-1H-pyrrole-2,5-diones and functionalization to tria

Directory of Open Access Journals (Sweden)

Bakhat Ali

2017-05-01

Full Text Available A series of alkynyl maleimides were prepared via one-step cross-coupling reaction using bromomaleimide and acetylenes under the Sonogashira conditions, affording 1-((4-methoxyphenyl-3-alkynes-1H-pyrrole-2,5-diones in good to high yields. These products were subsequently converted in the corresponding 1,2,3-triazole using conventional click chemistry approach. The alkynyl maleimide compound (8g crystallized in the triclinic space group P1 with unit cell parameters a = 5.3692(6, b = 9.2513(10, c = 10.3070(11 Å, α = 85.349(4, β = 86.892(4, γ = 86.892(4°, V = 507.31(10 Å3, and Z = 1. In the crystal the molecules are stacked parallel to the c axis and held together through a C–H⋯π and a C–H⋯O interaction.

Influence of electron delocalization in heterocyclic core systems on the electrochemical communication in 2,5-di- and 2,3,4,5-tetraferrocenyl thiophenes, furans, and pyrroles.

Science.gov (United States)

Hildebrandt, Alexander; Schaarschmidt, Dieter; Claus, Ron; Lang, Heinrich

2011-11-07

A series of 2,5-di- and 2,3,4,5-tetraferrocenyl-substituted thiophenes, furans, and pyrroles were synthesized using the Negishi C,C cross-coupling protocol. The electronic and electrochemical properties of these compounds were investigated by cyclic voltammetry (CV), square wave voltammetry (SWV), and in situ UV-vis/NIR spectroscopy. The molecular structures of 2,5-diferrocenyl furan and 2,3,4,5-tetraferrocenyl-1-methyl-1H-pyrrole in the solid state are discussed. The ferrocenyls could sequentially be oxidized giving two or four reversible responses for the appropriate di- or tetraferrocenyl-substituted heterocyclic molecules. The observed ΔE°' values range between 186 and 450 mV. The NIR measurements confirm electronic communication as intervalence charge transfer (IVCT) absorptions were found in the corresponding mono- and in case of the tetraferrocenyl compounds also in the dicationic species. All compounds, except tetraferrocenyl thiophene (a class I system), were classified as class II systems according to Robin and Day. They show a linear relationship between ΔE°' and the IVCT oscillator strength f which could be shown for the first time in organometallic chemistry. This was possible because the series of molecules exhibit analogous geometries and hence, similar electrostatic properties. This correlation was confirmed by electro- and spectro-electrochemical measurements. Within these studies a new approach for the estimation of the effective electron transfer distances r(ab) is discussed. © 2011 American Chemical Society

INFLUENCE OF ELECTROPOLYMERIZATION METHOD ON MORPHOLOGIES AND CAPACITIVE PROPERTIES OF POLYPYRROLE FILMS GROWING ON SILICON

OpenAIRE

IMENE CHIKOUCHE; ALI SAHARI; AHMED ZOUAOUI

2014-01-01

Two methods of Pyrrole electropolymerization were investigated to prepare polypyrrole films growing onto n-doped silicon n-Si (111): Polypyrrole films prepared by galvanostatic method exhibits toroidal morphology for thin films, and mixture of toroidal and globular morphologies for thick films. Polypyrrole films obtained from this method were characterized by lower surface roughness. Electropolymerization of pyrrole by potentiodynamic method provided Polypyrrole films with beans-like structur...

Electrochemical immunosensor for the determination of insulin-like growth factor-1 using electrodes modified with carbon nanotubes-poly(pyrrole propionic acid) hybrids.

Science.gov (United States)

Serafín, V; Agüí, L; Yáñez-Sedeño, P; Pingarrón, J M

2014-02-15

An amperometric immunosensor for the determination of the hormone insulin-like growth factor 1 (IGF1) is reported for the first time in this work. As electrochemical transducer, a multiwalled carbon nanotubes-modified glassy carbon electrode on which poly(pyrrole propionic acid) was electropolymerized was prepared. This approach provided a high content of surface confined carboxyl groups suitable for direct covalent binding of anti-IGF1 monoclonal antibody. A sandwich-type immunoassay using a polyclonal antibody labeled with peroxidase, hydrogen peroxide as the enzyme substrate and catechol as redox mediator was employed to monitor the affinity reaction. All the variables involved in the preparation of the modified electrode were optimized and the electrodes were characterized by electrochemical impedance spectroscopy and cyclic voltammetry. Moreover, the different experimental variables affecting the amperometric response of the immunosensor were also optimized. The calibration graph for IGF1 showed a range of linearity extending from 0.5 to 1000 pg/mL, with a detection limit, 0.25 pg/mL, more than 100 times lower than the lowest values reported for the ELISA immunoassays available for IGF1 (30 pg/mL, approximately). Excellent reproducibility for the measurements carried out with different immunosensors and selectivity against other hormones were also evidenced. A commercial human serum spiked with IGF1 at different levels between 0.01 and 10.0 ng/mL was analyzed with good results. © 2013 Elsevier B.V. All rights reserved.

Small Molecules Derived from Thieno[3,4-c]pyrrole-4,6-dione (TPD) and Their Use in Solution Processed Organic Solar Cells.

Science.gov (United States)

Garcias-Morales, Cesar; Romero-Borja, Daniel; Maldonado, José-Luis; Roa, Arián E; Rodríguez, Mario; García-Merinos, J Pablo; Ariza-Castolo, Armando

2017-09-30

In this work, microwave synthesis, chemical, optical and electrochemical characterization of three small organic molecules, TPA-TPD , TPA-PT-TPD and TPA-TT-TPD with donor-acceptor structure and their use in organic photovoltaic cells are reported. For the synthesis, 5-(2-ethylhexyl)-4 H -thieno[3,4- c ]pyrrole-4,6(5 H )-dione was used as electron withdrawing fragment while the triphenylamine was used as electron donating fragment. Molecular electronic geometry and electronic distribution density were established by density functional theory (DFT) calculations and confirmed by optical and chemical characterization. These molecules were employed as electron-donors in the active layer for manufacturing bulk heterojunction organic solar cells, where [6,6]-phenyl C71 butyric acid methyl ester (PC71BM) was used as electron-acceptor. As cathode, Field's metal (FM), an eutectic alloy (Bi/In/Sn: 32.5%, 51%, and 16.5%, respectively) with a melting point above 62 °C, was easily deposited by drop casting under vacuum-free process and at air atmosphere. Prepared devices based on TPA-TPD :PC71BM (1:4 w / w ratio) presented a large V OC = 0.97 V, with J SC = 7.9 mA/cm², a FF = 0.34, then, a power conversion efficiency (PCE) of 2.6%.

A comparative study of aroma-active compounds between dark and milk chocolate: relationship to sensory perception.

Science.gov (United States)

Liu, Jianbin; Liu, Mengya; He, Congcong; Song, Huanlu; Guo, Jia; Wang, Ye; Yang, Haiying; Su, Xiaoxia

2015-04-01

The most important aroma-active compounds of two types of chocolate and cocoa liquor used for their production were analysed by gas chromatography-olfactometry-mass spectrometry (GC-O-MS) and aroma extract dilution analysis (AEDA). Furthermore, the relationship between odorants and sensory perception of chocolate was measured by quantitative analysis, sensory evaluation and correlation analysis. In addition, some chemicals were added to the original dark or milk chocolate to validate their roles in the aroma property of chocolate. A total of 32 major aroma-active compounds were identified in the chocolate with the flavour dilution factors of 27-729 by AEDA, including seven aldehydes, six pyrazines, three pyrroles, four carboxylic acids, four lactones, two alcohols, two ketones, one ester, one pyrone, one furan and one sulfur-containing compound. Further quantitative analysis showed that dark chocolate had higher contents of pyrazine, pyrrole, carboxylic acids, alcohols and Strecker aldehydes, whereas the concentration of lactones, esters, long chain aldehydes and ketones were higher in the milk type. Differences in volatile composition and descriptive flavour attributes between the dark and milk chocolate were observed. The relationship between aroma-active compounds and sensory perception in the chocolate was verified. © 2014 Society of Chemical Industry.

Particle surface area and bacterial activity in recirculating aquaculture systems

DEFF Research Database (Denmark)

Pedersen, Per Bovbjerg; von Ahnen, Mathis; Fernandes, Paulo

2017-01-01

Suspended particles in recirculating aquaculture systems (RAS) provide surface area that can be colonized by bacteria. More particles accumulate as the intensity of recirculation increases thus potentially increasing the bacterial carrying capacity of the systems. Applying a recent, rapid, culture...... but may provide significant surface area. Hence, the study substantiates that particles in RAS provide surface area supporting bacterial activity, and that particles play a key role in controlling the bacterial carrying capacity at least in less intensive RAS. Applying fast, culture-independent techniques......-independent fluorometric detection method (Bactiquant®) for measuring bacterial activity, the current study explored the relationship between total particle surface area (TSA, derived from the size distribution of particles >5 μm) and bacterial activity in freshwater RAS operated at increasing intensity of recirculation...

Potential Biosignificant Interest and Surface Activity of Efficient Heterocyclic Derivatives.

Science.gov (United States)

El-Sayed, Refat; Althagafi, Ismail

2016-01-01

Some functionalized pyridine and fused system derivatives were synthesized using enaminonitrile derivative 5 as a starting material for the reaction, with various reagents under different conditions. Propoxylation of these compounds using different moles of propylene oxide (3, 5 and 7 moles) leads to a novel group of surface active agents. The antimicrobial and surface activities of the synthesized compounds were investigated. Most of the evaluated compounds proved to be active as antibacterial and antifungal agents and showed good surface activity, which makes them suitable for diverse applications such as the manufacturing of emulsifiers, cosmetics, drugs, pesticides, etc. Additionally, biodegradation testing exhibits significant breakdown within six to seven days, and hence, lowers the toxicity to human beings and becomes environmentally friendly.

Surface properties of activated carbon treated by cold plasma heating

Energy Technology Data Exchange (ETDEWEB)

Norikazu, Kurano [Shigematsu works Co. Ltd., 267 Yashita, Iwatsuki 3390046 (Japan); Yamada, Hiroshi [Shigematsu works Co. Ltd., 267 Yashita, Iwatsuki 3390046 (Japan); Yajima, Tatsuhiko [Faculty of Engineering, Saitama Institute of Technology, 1690 Fusoiji, Okabe 3690293 (Japan); Sugiyama, Kazuo [Faculty of Engineering, Saitama University, 255 Shimo-okubo, Sakura-Ku, Saitama 3388570 (Japan)]. E-mail: sugi@apc.saitama-u.ac.jp

2007-03-12

To modify the surface properties of activated carbon powders, we have applied the cold plasma treatment method. The cold plasma was used to be generated in the evacuated reactor vessel by 2.45 GHz microwave irradiation. In this paper, changes of surface properties such as distribution of acidic functional groups and roughness morphology were examined. By the cold plasma treatment, activated carbons with large specific surface area of ca. 2000 m{sup 2}/g or more could be prepared in a minute. The amount of every gaseous organic compound adsorbed on the unit gram of treated activated carbons was more increased that on the unit gram of untreated carbons. Especially, the adsorbed amount of carbon disulfide was remarkably increased even if it was compared by the amount per unit surface area. These results suggest that the surface property of the sample was modified by the plasma treatment. It became apparent by observing SEM photographs that dust and impure particles in macropores of activated carbons were far more reduced by the plasma treatment than by the conventional heating in an electric furnace under vacuum. In addition, a bubble-like surface morphology of the sample was observed by AEM measurement. The amount of acidic functional groups at the surface was determined by using the Boehm's titration method. Consequently, the increase of lactone groups and the decrease of carboxyl groups were also observed.

Surface-Activated Amorphous Alloy Fuel Electrodes for Methanol Fuel Cell

OpenAIRE

Asahi, Kawashima; Koji, Hashimoto; The Research Institute for Iron, Steel and Other Metals; The Research Institute for Iron, Steel and Other Metals

1983-01-01

Amorphous alloy electrodes for electrochemical oxidation of methanol and its derivatives were obtained by the surface activation treatment consisting of electrodeposition of zinc on as-quenched amorphous alloy substrates, heating at 200-300℃ for 30 min, and subsequently leaching of zinc in an alkaline solution. The surface activation treatment provided a new method for the preparation of a large surface area on the amorphous alloys. The best result for oxidation of methanol, sodium formate an...

Photodissociation dynamics in the first absorption band of pyrrole. I. Molecular Hamiltonian and the Herzberg-Teller absorption spectrum for the A12(π σ* ) ←X˜ 1 A1(π π ) transition

Science.gov (United States)

Picconi, David; Grebenshchikov, Sergy Yu.

2018-03-01

This paper opens a series in which the photochemistry of the two lowest πσ* states of pyrrole and their interaction with each other and with the ground electronic state X ˜ are studied using ab initio quantum mechanics. New 24-dimensional potential energy surfaces for the photodissociation of the N-H bond and the formation of the pyrrolyl radical are calculated using the multiconfigurational perturbation theory (CASPT2) for the electronic states X ˜ (π π ) , 11A2(πσ*), and 11B1(πσ*) and locally diabatized. In this paper, the ab initio calculations are described and the photodissociation in the state 11A2(πσ*) is analyzed. The excitation 11 A2←X ˜ is mediated by the coordinate dependent transition dipole moment functions constructed using the Herzberg-Teller expansion. Nuclear dynamics, including 6, 11, and 15 active degrees of freedom, are studied using the multi-configurational time-dependent Hartree method. The focus is on the frequency resolved absorption spectrum as well as on the dissociation time scales and the resonance lifetimes. Calculations are compared with available experimental data. An approximate convolution method is developed and validated, with which absorption spectra can be calculated and assigned in terms of vibrational quantum numbers. The method represents the total absorption spectrum as a convolution of the diffuse spectrum of the detaching H-atom and the Franck-Condon spectrum of the heteroaromatic ring. Convolution calculation requires a minimal quantum chemical input and is a promising tool for studying the πσ* photodissociation in model biochromophores.

High surface area microporous activated carbons prepared from Fox nut (Euryale ferox) shell by zinc chloride activation

Energy Technology Data Exchange (ETDEWEB)

Kumar, Arvind; Mohan Jena, Hara, E-mail: hmjena@nitrkl.ac.in

2015-11-30

Graphical abstract: - Highlights: • Activated carbons have been prepared from Fox nutshell with chemical activation using ZnCl{sub 2}. • The thermal behavior of the raw material and impregnated raw material has been carried out by thermogravimetric analysis. • The characterizations of the prepared activated carbons have been determined by nitrogen adsorption–desorption isotherms, FTIR, XRD, and FESEM. • The BET surface area and total pore volume of prepared activated carbon has been obtained as 2869 m{sup 2}/g, 2124 m{sup 2}/g, and 1.96 cm{sup 3}/g, respectively. • The microporous surface area, micropore volume, and microporosity percentage of prepared activated carbon has been obtained as 2124 m{sup 2}/g, 1.68 cm{sup 3}/g, and 85.71%, respectively. - Abstract: High surface area microporous activated carbon has been prepared from Fox nutshell (Euryale ferox) by chemical activation with ZnCl{sub 2} as an activator. The process has been conducted at different impregnation (ZnCl{sub 2}/Fox nutshell) ratios (1–2.5) and carbonization temperatures (500–700 °C). The thermal decomposition behavior of Fox nutshell and impregnated Fox nutshell has been carried out by thermogravimetric analysis. The pore properties including the BET surface area, micropore surface area, micropore volume, and pore size distribution of the activated carbons have been determined by nitrogen adsorption–desorption isotherms at −196 °C using the BET, t-plot method, DR, and BJH methods. The BET surface area, the microporous surface area, total pore volume, and micropore volume have been obtained as 2869 m{sup 2}/g, 2124 m{sup 2}/g, 1.96 cm{sup 3}/g, and 1.68 cm{sup 3}/g, respectively, and the microporosity percentage of the prepared activated carbon is 85.71%. The prepared activated carbons have been also characterized with instrumental methods such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM).

High surface area microporous activated carbons prepared from Fox nut (Euryale ferox) shell by zinc chloride activation

International Nuclear Information System (INIS)

Kumar, Arvind; Mohan Jena, Hara

2015-01-01

Graphical abstract: - Highlights: • Activated carbons have been prepared from Fox nutshell with chemical activation using ZnCl 2 . • The thermal behavior of the raw material and impregnated raw material has been carried out by thermogravimetric analysis. • The characterizations of the prepared activated carbons have been determined by nitrogen adsorption–desorption isotherms, FTIR, XRD, and FESEM. • The BET surface area and total pore volume of prepared activated carbon has been obtained as 2869 m 2 /g, 2124 m 2 /g, and 1.96 cm 3 /g, respectively. • The microporous surface area, micropore volume, and microporosity percentage of prepared activated carbon has been obtained as 2124 m 2 /g, 1.68 cm 3 /g, and 85.71%, respectively. - Abstract: High surface area microporous activated carbon has been prepared from Fox nutshell (Euryale ferox) by chemical activation with ZnCl 2 as an activator. The process has been conducted at different impregnation (ZnCl 2 /Fox nutshell) ratios (1–2.5) and carbonization temperatures (500–700 °C). The thermal decomposition behavior of Fox nutshell and impregnated Fox nutshell has been carried out by thermogravimetric analysis. The pore properties including the BET surface area, micropore surface area, micropore volume, and pore size distribution of the activated carbons have been determined by nitrogen adsorption–desorption isotherms at −196 °C using the BET, t-plot method, DR, and BJH methods. The BET surface area, the microporous surface area, total pore volume, and micropore volume have been obtained as 2869 m 2 /g, 2124 m 2 /g, 1.96 cm 3 /g, and 1.68 cm 3 /g, respectively, and the microporosity percentage of the prepared activated carbon is 85.71%. The prepared activated carbons have been also characterized with instrumental methods such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and field emission scanning electron microscopy (FESEM).

Preparation and microwave absorbing properties of nickel-coated graphite nanosheet with pyrrole via in situ polymerization

International Nuclear Information System (INIS)

Yang Yongqing; Qi Shuhua; Wang Jianning

2012-01-01

Highlights: ► NanoG was prepared and chemically coated by nano-Ni. ► PPy/NanoG and PPy/Ni/NanoG were prepared via in situ polymerization. ► The samples were characterized by SEM, XRD, EDS and FTIR. ► PPy/NanoG and PPy/Ni/NanoG exhibit good electromagnetic properties. - Abstract: Nanocomposites PPy/NanoG and PPy/Ni/NanoG were prepared via in situ polymerization of pyrrole in the presence of NanoG and nickel-coated graphite nanosheet (Ni/NanoG), respectively. The morphologies and nanostructures of NanoG, Ni/NanoG, PPy, PPy/NanoG and PPy/Ni/NanoG were characterized by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), Fourier transmission infrared (FTIR) and X-ray diffraction analysis (XRD). Results show that most of PPy chains disperse on NanoG and Ni/NanoG's surfaces for the high aspect ratio (300–500) of NanoG and Ni/NanoG. From the thermogravimetric analysis (TG) it can be seen that the introduction of Ni and NanoG leads the composites PPy/NanoG and PPy/Ni/NanoG to exhibit a better thermal stability than pure PPy. According to the four-point-probe test, the conductivities of the final PPy/NanoG and PPy/Ni/NanoG composites are dramatically increased compared to pure PPy. Measurement of electromagnetic parameters shows that the reflection loss (R) of PPy/Ni/NanoG is below −19 dB at the X band (8.2–12.4 GHz) and the minimum loss value is −23.46 dB at 9.88 GHz. The reflection loss of PPy/NanoG is below −10 dB at 8.2–12.4 GHz and the minimum loss value is −13.44 dB at 10.28 GHz. The microwave absorbing properties of PPy/NanoG and PPy/Ni/NanoG are superior to those of PPy.

Using of the surface activation method for enhancement of machine realibility

International Nuclear Information System (INIS)

Postnikov, V.I.; Garbar, I.N.

1979-01-01

A surface activation method is described for controlling the wear of units and details, allowing one to measure the wear at continuous operation of the mechanism by any program. The main advantages of the surface activation method for the wear tests are shown. By means of that method it was possible to develop a simultaneous controlling conjugate detail wear, and a method of different-activity brands, as well as the method for repeated activation of details. Development of theory for the engineering and technology of engine wear control by the surface activation method allowed one to improve the efficiency and reduce the time of research in the field of friction and wear

A trial fabrication of activity standard surface sources and positional standard surface sources for an imaging plate system

International Nuclear Information System (INIS)

Sato, Yasushi; Hino, Yoshio; Yamada, Takahiro; Matsumoto, Mikio

2003-01-01

An imaging plate system can detect low level activity, but quantitative analysis is difficult because there are no adequate standard surface sources. A new fabrication method was developed for standard surface sources by printing on a sheet of paper using an ink-jet printer with inks in which a radioactive material was mixed. The fabricated standard surface sources had high uniformity, high positional resolution arbitrary shapes and a broad intensity range. The standard sources were used for measurement of surface activity as an application. (H. Yokoo)

Effects of Activated Carbon Surface Property on Structure and Activity of Ru/AC Catalysts

Science.gov (United States)

Xu, S. K.; Li, L. M.; Guo, N. N.

2018-05-01

The activated carbon (AC) was modified by supercritical (SC) methanol, HNO3 oxidation, or HNO3 oxidation plus SC methanol, respectively. Then, the original and the modified AC were used as supports for Ru/AC catalysts prepared via the impregnation method. The results showed that the SC methanol modification decreased the content of surface acidic groups of AC. While HNO3 oxidation displayed the opposite behavior. Furthermore, the dispersion of ruthenium and the activity of catalysts were highly dependent on the content of surface acidic groups, and the SC methanol modified sample exhibited the highest activity for hydrogenation of glucose.

Study on the correlation between the surface active species of Pd/cordierite monolithic catalyst and its catalytic activity

International Nuclear Information System (INIS)

Liao, Hengcheng; Zuo, Peiyuan; Liu, Miaomiao

2016-01-01

Two Pd-loading routes and three Pd-precursor matters were adopted to prepare Pd/(Ce,Y)O_2/γ-Al_2O_3/cordierite monolithic catalyst. The surface active species on the catalyst were characterized by XPS, and its catalytic activity for methane combustion was tested, and the dynamics of the catalytic combustion reaction was also discussed. Pd-loading route and Pd-precursor mass have a significant influence on the catalytic activity and surface active species. The sol dipping method is more advanced than the aqueous solution impregnating method. PN-sol catalyst, by sol dipping combined with Pd(NO_3)_2-precursor, has the best catalytic activity. The physical reason is the unique active Pd phase coexisting with active PdO phase on the surface, and thus the Pd3d_5_/_2 binding energy of surface species and apparent activation energy of combustion reaction are considerably decreased. The catalytic activity index, Pd3d_5_/_2 binding energy and apparent activation energy are highly tied each other with exponential relations.

Complete dechlorination of 2,4-dichlorophenol in aqueous solution on palladium/polymeric pyrrole-cetyl trimethyl ammonium bromide/foam-nickel composite electrode

Energy Technology Data Exchange (ETDEWEB)

Sun, Zhirong, E-mail: zrsun@bjut.edu.cn [College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China); Wei, Xuefeng; Han, Yanbo; Tong, Shan [College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124 (China); Hu, Xiang, E-mail: huxiang99@163.com [College of Chemical Engineering, Beijing University of Chemical Technology, Beijing 100029 (China)

2013-01-15

Highlights: ► Pd/PPy-CTAB/foam-Ni electrode with high surface area and low Pd content was prepared. ► The composite electrode was applied to dechlorination of 2,4-DCP in aqueous solution. ► Complete dechlorination of 2,4-DCP was achieved with higher current efficiency. ► Removal efficiency kept 100% after 10 times dechlorination on the stable electrode. ► The electrochemically reductive activation energy was 25.8 kJ mol{sup −1} in this system. -- Abstract: The electrochemically reductive dechlorination of 2,4-dichlorophenol (2,4-DCP) in aqueous solution on palladium/polymeric pyrrole-cetyl trimethyl ammonium bromide/foam-nickel electrode (Pd/PPy-CTAB/foam-Ni electrode) was investigated in this paper. Pd/PPy-CTAB/foam-Ni electrode was prepared and characterized by cyclic voltammetry (CV), scanning electron microscope (SEM), X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) adsorption and inductively coupled plasma-atomic emission spectroscopy (ICP-AES). The influences of some experimental factors such as the dechlorination current, dechlorination time and the initial pH on the removal efficiency and the current efficiency of 2,4-DCP dechlorination on Pd/PPy-CTAB/foam-Ni electrode were studied. Complete removal of 2,4-DCP was achieved and the current efficiency of 47.4% could be obtained under the conditions of the initial pH of 2.2, the dechlorination current of 5 mA and the dechlorination time of 50 min when the initial 2,4-DCP concentration was 100 mg L{sup −1}. The analysis of high performance liquid chromatography (HPLC) identified that the intermediate products were 2-chlorophenol (2-CP) and 4-chlorophenol (4-CP). The final products were mainly phenol. Its further reduction product cyclohexanone was also detected. The electrocatalytic dechlorination pathways of 2,4-DCP on Pd/PPy-CTAB/foam-Ni electrode were discussed. The stability of the electrode was favorable that it could keep dechlorination efficiency at 100% after having been reused

The effect of β-saturated pyrrolic rings on the electronic structures and aromaticity of magnesium porphyrin derivatives: a density functional study.

Science.gov (United States)

Wan, Liang; Qi, Dongdong; Zhang, Yuexing

2011-09-01

Density functional theory (DFT) calculation on the molecular structures, molecular orbitals, electronic absorption spectra, and magnetic properties of magnesium porphyrin (MgPor) and a series of five hydrogenated magnesium porphyrin complexes with different number of β-saturated pyrrolic rings, namely MgPor-β-1Hy, MgPor-β-opp-2Hy, MgPor-β-adj-2Hy, MgPor-β-3Hy, and MgPor-β-4Hy, clarifies the red-shift of the lowest energy absorption band from chlorophyll a to bacteriochlorophyll and reveals the strong chemical stability for both of them. The energy levels of highest occupied molecular orbitals (HOMO) and HOMO-1 for MgPor are reversed upon hydrogenation at β-positions (2 and 3, 7 and 8, 12 and 13, and 17 and 18) of porphyrin ring. Along with the increase of β-saturated pyrrolic rings from 1, 2, 3, to 4, the HOMO energy increases from -4.78 eV to -3.10 eV in a regular manner. In contrast, the lowest unoccupied molecular orbitals (LUMO) energy levels of MgPor, MgPor-β-1Hy, and MgPor-β-opp-2Hy are very similar with each other. As a result, the lowest energy absorption band involving main transition from HOMO to LUMO is red-shifted from MgPor-β-1Hy to MgPor-β-opp-2Hy which is representative of chlorophyll a and bacteriochlorophyll, respectively. Natural hydroporphyrins represented by MgPor, MgPor-β-1Hy, and MgPor-β-opp-2Hy have turned out to be aromatic and stable enough, in good accordance with the ubiquity of their derivatives in the nature. In contrast, MgPor-β-adj-2Hy, MgPor-β-3Hy, and MgPor-β-4Hy with relatively weak aromaticity seem to be unstable and therefore were not found in nature. Copyright © 2011 Elsevier Inc. All rights reserved.

Preparation of High Surface Area Activated Carbon from Spent Phenolic Resin by Microwave Heating and KOH Activation

Science.gov (United States)

Cheng, Song; Zhang, Libo; Zhang, Shengzhou; Xia, Hongying; Peng, Jinhui

2018-01-01

The spent phenolic resin is as raw material for preparing high surface area activated carbon (HSAAC) by microwave-assisted KOH activation. The effects of microwave power, activation duration and impregnation ratio (IR) on the iodine adsorption capability and yield of HSAAC were investigated. The surface characteristics of HSAAC were characterized by nitrogen adsorption isotherms, FTIR, SEM and TEM. The operating variables were optimized utilizing the response surface methodology (RSM) and were identified to be microwave power of 700 W, activation duration of 15 min and IR of 4, corresponding to a yield of 51.25 % and an iodine number of 2,384 mg/g. The pore structure parameters of the HSAAC, i. e., Brunauer-Emmett-Teller (BET) surface area, total pore volume, and average pore diameter were estimated to be 4,269 m2/g, 2.396 ml/g and 2.25 nm, respectively, under optimum conditions. The findings strongly support the feasibility of microwave-assisted KOH activation for preparation of HSAAC from spent phenolic resin.

Active surface model improvement by energy function optimization for 3D segmentation.

Science.gov (United States)

Azimifar, Zohreh; Mohaddesi, Mahsa

2015-04-01

This paper proposes an optimized and efficient active surface model by improving the energy functions, searching method, neighborhood definition and resampling criterion. Extracting an accurate surface of the desired object from a number of 3D images using active surface and deformable models plays an important role in computer vision especially medical image processing. Different powerful segmentation algorithms have been suggested to address the limitations associated with the model initialization, poor convergence to surface concavities and slow convergence rate. This paper proposes a method to improve one of the strongest and recent segmentation algorithms, namely the Decoupled Active Surface (DAS) method. We consider a gradient of wavelet edge extracted image and local phase coherence as external energy to extract more information from images and we use curvature integral as internal energy to focus on high curvature region extraction. Similarly, we use resampling of points and a line search for point selection to improve the accuracy of the algorithm. We further employ an estimation of the desired object as an initialization for the active surface model. A number of tests and experiments have been done and the results show the improvements with regards to the extracted surface accuracy and computational time of the presented algorithm compared with the best and recent active surface models. Copyright © 2015 Elsevier Ltd. All rights reserved.

Supercapacitance of Single-Walled Carbon Nanotubes-Polypyrrole Composites

Directory of Open Access Journals (Sweden)

Matei Raicopol

2013-01-01

Full Text Available The composites based on carbon nanotubes (CNTs and conducting polymers (CPs are promising materials for supercapacitor devices due to their unique nanostructure that combines the large pseudocapacitance of the CPs with the fast charging/discharging double-layer capacitance and excellent mechanical properties of the CNTs. Here, we report a new electrochemical method to obtain polypyrrole (PPY/single-walled carbon nanotube (SWCNT composites. In the first step, the SWCNTs are covalently functionalized with monomeric units of pyrrole by esterification of acyl chloride functionalized SWCNTs and N-(6-hydroxyhexylpyrrole. In the second step, the PPY/SWCNTs composites are obtained by copolymerizing the pyrrole monomer with the pyrrole units grafted on SWCNTs surface using controlled potential electrolysis. The composites were further characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The results showed good electrochemical charge storage properties for the synthesized composites based on PPY and SWCNTs covalently functionalized with pyrrole units making them promising electrode materials for high power supercapacitors.

Quantitation of Pyrrole-Imidazole Polyamide in Rat Plasma by High-Performance Liquid Chromatography Coupled with UV Detection

Directory of Open Access Journals (Sweden)

Tomonori Kamei

2012-01-01

Full Text Available A simple and robust method using high-performance liquid chromatography with UV detection was developed and validated for the determination of six pyrrole-imidazole (PI polyamides (HN.49, TGF-β1f, TGF-β1t, HN.50f, HN.50t, and LOX-1 in rat plasma. After the plasma proteins were precipitated with methanol containing phenacetin as an internal standard, the analytes were separated on a Luna C18 (2 (5 μm, 4.6×150 mm. Calibration curves were linear over the range of 0.5 to 200 μg/mL for HN.49, 0.25 to 200 μg/mL for TGF-β1f, TGF-β1t, HN.50t, and LOX-1, 1 to 200 μg/mL for HN.50f in rat plasma. The inter- and intraday precision were below 15%, and the accuracy was within 15% at the quality controls. The validated method was successfully applied to sample analysis for the pharmacokinetic study.

Room temperature Cu-Cu direct bonding using surface activated bonding method

International Nuclear Information System (INIS)

Kim, T.H.; Howlader, M.M.R.; Itoh, T.; Suga, T.

2003-01-01

Thin copper (Cu) films of 80 nm thickness deposited on a diffusion barrier layered 8 in. silicon wafers were directly bonded at room temperature using the surface activated bonding method. A low energy Ar ion beam of 40-100 eV was used to activate the Cu surface prior to bonding. Contacting two surface-activated wafers enables successful Cu-Cu direct bonding. The bonding process was carried out under an ultrahigh vacuum condition. No thermal annealing was required to increase the bonding strength since the bonded interface was strong enough at room temperature. The chemical constitution of the Cu surface was examined by Auger electron spectroscope. It was observed that carbon-based contaminations and native oxides on copper surface were effectively removed by Ar ion beam irradiation for 60 s without any wet cleaning processes. An atomic force microscope study shows that the Ar ion beam process causes no surface roughness degradation. Tensile test results show that high bonding strength equivalent to bulk material is achieved at room temperature. The cross-sectional transmission electron microscope observations reveal the presence of void-free bonding interface without intermediate layer at the bonded Cu surfaces

Osteoinductive activity of insulin-functionalized cell culture surfaces obtained using diazonium chemistry

Science.gov (United States)

Mikulska, Anna; Filipowska, Joanna; Osyczka, Anna; Nowakowska, Maria; Szczubiałka, Krzysztof

2014-12-01

Polymeric surfaces suitable for cell culture (DR/Pec) were constructed from diazoresin (DR) and pectin (Pec) in a form of ultrathin films using the layer-by-layer (LbL) technique. The surfaces were functionalized with insulin using diazonium chemistry. Such functionalized surfaces were used to culture human mesenchymal stem cells (hMSCs) to assess their suitability for bone tissue engineering and regeneration. The activity of insulin immobilized on the surfaces (DR/Pec/Ins) was compared to that of insulin dissolved in the culture medium. Human MSC grown on insulin-immobilized DR/Pec surfaces displayed increased proliferation and higher osteogenic activity. The latter was determined by means of alkaline phosphatase (ALP) activity, which increases at early stages of osteoblasts differentiation. Insulin dissolved in the culture medium did not stimulate cell proliferation and its osteogenic activity was significantly lower. Addition of recombinant human bone morphogenetic protein 2 (rhBMP-2) to the culture medium further increased ALP activity in hMSCs indicating additive osteogenic action of immobilized insulin and rhBMP-2

Osteoinductive activity of insulin-functionalized cell culture surfaces obtained using diazonium chemistry

Directory of Open Access Journals (Sweden)

Anna eMikulska

2015-01-01

Full Text Available Polymeric surfaces suitable for cell culture (DR/Pec were constructed from diazoresin (DR and pectin (Pec in a form of ultrathin films using the layer-by-layer (LbL technique. The surfaces were functionalized with insulin using diazonium chemistry. Such functionalized surfaces were used to culture human mesenchymal stem cells (hMSCs to assess their suitability for bone tissue engineering and regeneration. The activity of insulin immobilized on the surfaces (DR/Pec/Ins was compared to that of insulin dissolved in the culture medium. Human MSC grown on insulin-immobilized DR/Pec surfaces displayed increased proliferation and higher osteogenic activity. The latter was determined by means of alkaline phosphatase (ALP activity, which increases at early stages of osteoblasts differentiation. Insulin dissolved in the culture medium did not stimulate cell proliferation and its osteogenic activity was significantly lower. Addition of recombinant human bone morphogenetic protein 2 (rhBMP-2 to the culture medium further increased ALP activity in hMSCs indicating additive osteogenic action of immobilized insulin and rhBMP-2

Effect of non-electroactive additives on the early stage pyrrole electropolymerization on indium tin oxide electrodes

Energy Technology Data Exchange (ETDEWEB)

Castro-Beltran, A. [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ave. Pedro de Alba s/n, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Centro de Innovación Investigación y Desarrollo en Ingeniería y Tecnología (CIIDIT), Universidad Autónoma de Nuevo León, PIIT-Monterrey C.P. 66600 Apodaca, N.L. (Mexico); Dominguez, C.; Bahena-Uribe, D. [Centro Investigación en Ingeniería y Ciencias Aplicadas (CIICAp), Universidad Autónoma del Estado de Morelos, Av. Universidad 1001, Col. Chamilpa, C.P. 62209 Cuernavaca, Mor. (Mexico); Sepulveda-Guzman, S., E-mail: selene.sepulvedagz@uanl.edu.mx [Facultad de Ingeniería Mecánica y Eléctrica, Universidad Autónoma de Nuevo León, Ave. Pedro de Alba s/n, Ciudad Universitaria, C.P. 66451 San Nicolás de los Garza, N.L. (Mexico); Centro de Innovación Investigación y Desarrollo en Ingeniería y Tecnología (CIIDIT), Universidad Autónoma de Nuevo León, PIIT-Monterrey C.P. 66600 Apodaca, N.L. (Mexico); Cruz-Silva, R. [Research Center for Exotic NanoCarbon, Shinshu University, 4-17-1 Wakasato, Nagano 380-8553 (Japan)

2014-09-01

The use of non-electroactive additives during electrodeposition of conducting polymers has long been used to modify the properties of deposited films. These additives can improve the adhesion, and not only change the morphology and deposition rate but also modify the chemical composition of the electrodeposited polymer. Several compounds have been used to modify deposition of polypyrrole; however, there is no systematic study of these compounds. In this work, we comparatively studied several water soluble chemical compounds, a cationic polymer, an anionic polymer, a cationic surfactant, and an anionic surfactant during potentiostatic electrodeposition of polypyrrole. In order to study the effect of these compounds on the interface, where the electrochemical polymerization takes place, we used electrochemical impedance spectroscopy. The morphology during the initial stage of growth was studied by atomic force microscopy, whereas the resulting polypyrrole films were observed by scanning electron microscopy. - Highlights: • Early-stage polymerization polypyrrole particles on indium tin oxide (ITO). • Anionic additives promote pyrrole oxidation and polypyrrole film growth on ITO. • Cationic polyelectrolyte promotes adhesion between ITO and polypyrrole film. • Non-electroactive additives strongly influence polypyrrole nucleation on ITO.

An alternative laser driven photodissociation mechanism of pyrrole via π*1σ/S0 conical intersection

Science.gov (United States)

Nandipati, K. R.; Lan, Z.; Singh, H.; Mahapatra, S.

2017-06-01

A first principles quantum dynamics study of N-H photodissociation of pyrrole on the S0-1π σ*(A12) coupled electronic states is carried out with the aid of an optimally designed UV-laser pulse. A new photodissociation path, as compared to the conventional barrier crossing on the π*1σ state, opens up upon electronic transitions under the influence of pump-dump laser pulses, which efficiently populate both the dissociation channels. The interplay of electronic transitions due both to vibronic coupling and the laser pulse is observed in the control mechanism and discussed in detail. The proposed control mechanism seems to be robust, and not discussed in the literature so far, and is expected to trigger future experiments on the π*1σ photochemistry of molecules of chemical and biological importance. The design of the optimal pulses and their application to enhance the overall dissociation probability is carried out within the framework of optimal control theory. The quantum dynamics of the system in the presence of pulse is treated by solving the time-dependent Schrödinger equation in the semi-classical dipole approximation.

Controlling hydrogenation activity and selectivity of bimetallic surfaces and catalysts

Science.gov (United States)

Murillo, Luis E.

Studies of bimetallic systems are of great interest in catalysis due to the novel properties that they often show in comparison with the parent metals. The goals of this dissertation are: (1) to expand the studies of self-hydrogenation and hydrogenation reactions on bimetallic surfaces under ultra high vacuum conditions (UHV) using different hydrocarbon as probe molecules; (2) to attempt to correlate the surface science findings with supported catalyst studies under more realistic conditions; and (3) to investigate the competitive hydrogenation of C=C versus C=O bonds on Pt(111) modified by different 3d transition metals. Hydrogenation studies using temperature programmed desorption (TPD) on Ni/Pt(111) bimetallic surfaces have demonstrated an enhancement in the low temperature hydrogenation activity relative to that of clean Pt(111). This novel hydrogenation pathway can be achieved under UHV conditions by controlling the structures of the bimetallic surfaces. A low temperature hydrogenation activity of 1-hexene and 1-butene has been observed on a Pt-Ni-Pt(111) subsurface structure, where Ni atoms are mainly present on the second layer of the Pt(111) single crystal. These results are in agreement with previous studies of self-hydrogenation and hydrogenation of cyclohexene. However, a much higher dehydrogenation activity is observed in the reaction of cyclohexene to produce benzene, demonstrating that the hydrocarbon structure has an effect on the reaction pathways. On the other hand, self-hydrogenation of 1-butene is not observed on the Pt-Ni-Pt(111) surface, indicating that the chain length (or molecular weight) has a significant effect on the selfhydrogenation activity. The gas phase reaction of cyclohexene on Ni/Pt supported on alumina catalysts has also shown a higher self-hydrogenation activity in comparison with the same reaction performed on supported monometallic catalysts. The effects of metal loading and impregnation sequence of the metal precursors are

Development of SERS active fibre sensors

International Nuclear Information System (INIS)

Polwart, Ewan

2002-01-01

Surface-enhanced Raman scattering (SERS) is sensitive and selective and when coupled with fibre-optics could potentially produce an effective chemical sensing system. This thesis concerns the development of a single-fibre-based sensor, with an integral SERS-active substrate. A number of different methods for the manufacture of SERS-active surfaces on glass substrates were investigated and compared. The immobilisation of metal nanoparticles on glass functionalised with (3-aminopropyl)trimethoxysilane emerged as a suitable approach for the production of sensors. Substrates prepared by this approach were characterised using UV-visible spectroscopy, electron microscopy and Raman mapping. It was found that exposure of substrates to laser radiation led to a decrease in the signal recorded from adsorbed analytes. This speed of the decrease was shown to depend on the analyte, and the exciting wavelength and power. SERS-active fibre sensors were produced by immobilisation of silver nanoparticles at the distal end of a (3-aminopropyl)trimethoxysilane-derivatised optical fibre. These sensors were used to obtain spectra with good signal to noise ratios from 4-(benzotriazol-5-ylazo)-3,5-dimethoxyphenylamine and crystal violet. Sensing of dyes in effluent was also investigated. The development of sensors for the measurement of pH, by treating the SERS-active fibre tip with pH sensitive dyes is also described. Spectral changes were observed with these sensors as a response to the pH. Partial least squares regression was used to produce linear calibration models for the pH range 5-11 from which it was possible to predict the pH with an accuracy of ∼0.2 pH units. Some of the limitations of these sensors were explored. The feasibility of using these sensors for measurement of oxygen and thiols, was investigated. The measurement of oxygen using methylene blue as a transducer was demonstrated. Two transduction methodologies--reactions with iron porphyrins and pyrrole-2,5-diones

Microstructure and surface properties of lignocellulosic-based activated carbons

International Nuclear Information System (INIS)

González-García, P.; Centeno, T.A.; Urones-Garrote, E.; Ávila-Brande, D.; Otero-Díaz, L.C.

2013-01-01

Highlights: ► Activated carbons were produced by KOH activation at 700 °C. ► The observed nanostructure consists of highly disordered graphene–like layers with sp 2 bond content ≈ 95%. ► Textural parameters show high surface area (≈ 1000 m 2 /g) and pore width of 1.3–1.8 nm. ► Specific capacitance reaches values as high as 161 F/g. - Abstract: Low cost activated carbons have been produced via chemical activation, by using KOH at 700 °C, from the bamboo species Guadua Angustifolia and Bambusa Vulgaris Striata and the residues from shells of the fruits of Castanea Sativa and Juglans Regia as carbon precursors. The scanning electron microscopy micrographs show the conservation of the precursor shape in the case of the Guadua Angustifolia and Bambusa Vulgaris Striata activated carbons. Transmission electron microscopy analyses reveal that these materials consist of carbon platelet–like particles with variable length and thickness, formed by highly disordered graphene–like layers with sp 2 content ≈ 95% and average mass density of 1.65 g/cm 3 (25% below standard graphite). Textural parameters indicate a high porosity development with surface areas ranging from 850 to 1100 m 2 /g and average pore width centered in the supermicropores range (1.3–1.8 nm). The electrochemical performance of the activated carbons shows specific capacitance values at low current density (1 mA/cm 2 ) as high as 161 F/g in the Juglans Regia activated carbon, as a result of its textural parameters and the presence of pseudocapacitance derived from surface oxygenated acidic groups (mainly quinones and ethers) identified in this activated carbon.

Active screen plasma nitriding enhances cell attachment to polymer surfaces

International Nuclear Information System (INIS)

Kaklamani, Georgia; Bowen, James; Mehrban, Nazia; Dong, Hanshan; Grover, Liam M.; Stamboulis, Artemis

2013-01-01

Active screen plasma nitriding (ASPN) is a well-established technique used for the surface modification of materials, the result of which is often a product with enhanced functional performance. Here we report the modification of the chemical and mechanical properties of ultra-high molecular weight poly(ethylene) (UHMWPE) using 80:20 (v/v) N 2 /H 2 ASPN, followed by growth of 3T3 fibroblasts on the treated and untreated polymer surfaces. ASPN-treated UHMWPE showed extensive fibroblast attachment within 3 h of seeding, whereas fibroblasts did not successfully attach to untreated UHMWPE. Fibroblast-coated surfaces were maintained for up to 28 days, monitoring their metabolic activity and morphology throughout. The chemical properties of the ASPN-treated UHMWPE surface were studied using X-ray photoelectron spectroscopy, revealing the presence of C-N, C=N, and C≡N chemical bonds. The elastic modulus, surface topography, and adhesion properties of the ASPN-treated UHMWPE surface were studied over 28 days during sample storage under ambient conditions and during immersion in two commonly used cell culture media.

Maleimide-activated aryl diazonium salts for electrode surface functionalization with biological and redox-active molecules.

Science.gov (United States)

Harper, Jason C; Polsky, Ronen; Wheeler, David R; Brozik, Susan M

2008-03-04

A versatile and simple method is introduced for formation of maleimide-functionalized surfaces using maleimide-activated aryl diazonium salts. We show for the first time electrodeposition of N-(4-diazophenyl)maleimide tetrafluoroborate on gold and carbon electrodes which was characterized via voltammetry, grazing angle FTIR, and ellipsometry. Electrodeposition conditions were used to control film thickness and yielded submonolayer-to-multilayer grafting. The resulting phenylmaleimide surfaces served as effective coupling agents for electrode functionalization with ferrocene and the redox-active protein cytochrome c. The utility of phenylmaleimide diazonium toward formation of a diazonium-activated conjugate, followed by direct electrodeposition of the diazonium-modified DNA onto the electrode surface, was also demonstrated. Effective electron transfer was obtained between immobilized molecules and the electrodes. This novel application of N-phenylmaleimide diazonium may facilitate the development of bioelectronic devices including biofuel cells, biosensors, and DNA and protein microarrays.

Activation of interfacial enzymes at membrane surfaces

DEFF Research Database (Denmark)

Mouritsen, Ole G.; Andresen, Thomas Lars; Halperin, Avi

2006-01-01

A host of water-soluble enzymes are active at membrane surfaces and in association with membranes. Some of these enzymes are involved in signalling and in modification and remodelling of the membranes. A special class of enzymes, the phospholipases, and in particular secretory phospholipase A2 (s...

High-surface-area active carbon

International Nuclear Information System (INIS)

O'Grady, T.M.; Wennerberg, A.N.

1986-01-01

This paper describes the preparation and properties of a unique active carbon having exceptionally high surface areas, over 2500 m 2 /gm, and extraordinary adsorptive capacities. The carbon is made by a direct chemical activation route in which petroleum coke or other carbonaceous sources are reacted with excess potassium hydroxide at 400 0 to 500 0 C to an intermediate product that is subsequently pyrolyzed at 800 0 to 900 0 C to active carbon containing potassium salts. These are removed by water washing and the carbon is dried to produce a powdered product. A granular carbon can also be made by further processing the powdered carbon by using specialized granulation techniques. Typical properties of the carbon include Iodine Numbers of 3000 to 3600, methylene blue adsorption of 650 to 750 mg/gm, pore volumes of 2.0 to 2.6 cc/gm and less than 3.0% ash. This carbon's high adsorption capacities make it uniquely suited for numerous demanding applications in the medical area, purifications, removal of toxic substances, as catalyst carriers, etc

Pyrrole and 2,5-heptanedione in the urine of rats and 2,5-heptanedione in the urine of man: analytical determination of excretion upon exposure to n-heptane; Pyrrole und 2,5-Heptandion im Urin der Ratte und 2,5-Heptandion im Urin des Menschen: Analytische Bestimmung der Ausscheidung nach Exposition gegn n-Heptan

Energy Technology Data Exchange (ETDEWEB)

Stoermer, A.G.C.

1997-09-01

A method for quantifying levels of the neurotoxic metabolite 2,5-heptanedione in rats and man after experimental exposure to n-heptane was developed. It consisted in determining the quantity of 2,5-heptanedione excreted in urine and the relevant excretion kinetics. Moreover, the excretion of pyrrole in the urine of rats was measured. In the urine of non-exposed rats and man, a basic excretion of 2,5-heptanedione was measured, with the rates of excretion being 0.11 and 4.5 nmol per hour, respectively. This basic excretion of 2,5-heptanedione is assumed to have an endogenous cause. The quantitive investigation of the dose dependence of the excretion of 2,5-heptanedione and pyrrole in the urine of rats and of 2,5-heptanedione in the urine of man is a prerequisite for assessing the risk posed by n-heptane with a view to peripheral neuropathies. (orig./MG) [Deutsch] Ziel dieser Arbeit war die Entwicklung einer Methode zur Quantifizierung der Belastung von Ratte und Mensch mit dem neurotoxischen Metaboliten 2,5-Heptandion nach experimentellen Expositionen gegen n-Heptan. Dazu sollte jeweils die ausgeschiedene Menge und die zugehoerige Ausscheidungskinetik von 2,5-Heptandion im Urin bestimmt werden. Darueber hinaus sollte die Ausscheidung von Pyrrolen im Urin von Ratten gemessen werden. Im Urin von nicht exponierten Ratten und Menschen wurde eine Grundausscheidung von 2,5-Heptandion gefunden, wobei die Ausscheidungsraten jeweils 0,11 bzw. 4,5 nmol/h betrugen. Fuer die Grundausscheidung von 2,5-Heptandion wird ein endogener Ursprung angenommen. Die quantitativen Untersuchungen zur Dosisabhaengigkeit der Ausscheidung im Urin von 2,5-Heptandion und Pyrrolen bei der Ratte und von 2,5-Heptandion beim Menschen sind eine Grundvoraussetzung fuer eine Abschaetzung des Risikos von n-Heptan fuer periphere Neuropathien. (orig./MG)

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

International Nuclear Information System (INIS)

Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M.; Sapsay, V.I.; Klymchuk, D.O.; Puziy, A.M.

2012-01-01

Highlights: ► Phosphoric acid activation results in formation of carbons with acidic surface groups. ► Maximum amount of surface groups is introduced at impregnation ratio 1.25. ► Phosphoric acid activated carbons show high capacity to copper. ► Phosphoric acid activated carbons are predominantly microporous. ► Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S BET = 2081 m 2 /g, V tot = 1.1 cm 3 /g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0–2.6), weakly acidic carboxylic (pK = 4.7–5.0), enol/lactone (pK = 6.7–7.4; 8.8–9.4) and phenol (pK = 10.1–10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

Energy Technology Data Exchange (ETDEWEB)

Sych, N.V.; Trofymenko, S.I.; Poddubnaya, O.I.; Tsyba, M.M. [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine); Sapsay, V.I.; Klymchuk, D.O. [M.G. Kholodny Institute of Botany, National Academy of Sciences of Ukraine, 2 Tereshchenkivska St., 01601 Kyiv (Ukraine); Puziy, A.M., E-mail: alexander.puziy@ispe.kiev.ua [Institute for Sorption and Endoecology Problems, National Academy of Sciences of Ukraine, 13 General Naumov St., 03164 Kyiv (Ukraine)

2012-11-15

Highlights: Black-Right-Pointing-Pointer Phosphoric acid activation results in formation of carbons with acidic surface groups. Black-Right-Pointing-Pointer Maximum amount of surface groups is introduced at impregnation ratio 1.25. Black-Right-Pointing-Pointer Phosphoric acid activated carbons show high capacity to copper. Black-Right-Pointing-Pointer Phosphoric acid activated carbons are predominantly microporous. Black-Right-Pointing-Pointer Maximum surface area and pore volume achieved at impregnation ratio 1.0. - Abstract: Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 Degree-Sign C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (S{sub BET} = 2081 m{sup 2}/g, V{sub tot} = 1.1 cm{sup 3}/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

Electrosynthesis and catalytic activity of polymer-nickel particles composite electrode materials

International Nuclear Information System (INIS)

Melki, Tahar; Zouaoui, Ahmed; Bendemagh, Barkahoum; Oliveira, Ione M.F. de; Oliveira, Gilver F. de; Lepretre, Jean-Claude; Bucher, Christophe; Mou tet, Jean-Claude

2009-01-01

Nickel-polymer composite electrode materials have been synthesized using various strategies, all comprising the electrochemical reduction of nickel(II) cations or complexes, incorporated by either ion-exchange or complexation into various poly(pyrrole-carboxylate) thin films coated by oxidative electropolymerization onto carbon electrodes. The electrocatalytic activity and the stability of the different composites have been then evaluated in the course of the electrocatalytic hydrogenation of ketones and enones in aqueous electrolytes. The best results were obtained using nickel-polymer composites synthesized by electroreduction of nickel(II) ions complexed into polycarboxylate films, which are characterized by a high catalytic activity and a good operational stability. (author)

Electrosynthesis and catalytic activity of polymer-nickel particles composite electrode materials

Energy Technology Data Exchange (ETDEWEB)

Melki, Tahar; Zouaoui, Ahmed; Bendemagh, Barkahoum [Universite Ferhat Abbas, Setif (Algeria). Faculte des Sciences de l' Ingenieur. Dept. du Tronc Commun; Oliveira, Ione M.F. de; Oliveira, Gilver F. de [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Dept. de Quimica; Lepretre, Jean-Claude [UMR-5631 CNRS-INPG-UJF, St. Martin d' Heres Cedex (France). Lab. d' Electrochimie et de Physicochimie des Materiaux et Interfaces; Bucher, Christophe; Mou tet, Jean-Claude [Universite Joseph Fourier Grenoble 1 (France). Dept. de Chimie Moleculaire], e-mail: Jean-Claude.Moutet@ujf-grenoble.fr

2009-07-01

Nickel-polymer composite electrode materials have been synthesized using various strategies, all comprising the electrochemical reduction of nickel(II) cations or complexes, incorporated by either ion-exchange or complexation into various poly(pyrrole-carboxylate) thin films coated by oxidative electropolymerization onto carbon electrodes. The electrocatalytic activity and the stability of the different composites have been then evaluated in the course of the electrocatalytic hydrogenation of ketones and enones in aqueous electrolytes. The best results were obtained using nickel-polymer composites synthesized by electroreduction of nickel(II) ions complexed into polycarboxylate films, which are characterized by a high catalytic activity and a good operational stability. (author)

Improvement of silicon direct bonding using surfaces activated by hydrogen plasma treatment

CERN Document Server

Choi, W B; Lee Jae Sik; Sung, M Y

2000-01-01

The plasma surface treatment, using hydrogen gas, of silicon wafers was studied as a pretreatment for silicon direct bonding. Chemical reactions of the hydrogen plasma with the surfaces were used for both surface activation and removal of surface contaminants. Exposure of the silicon wafers to the plasma formed an active oxide layer on the surface. This layer was hydrophilic. The surface roughness and morphology were examined as functions of the plasma exposure time and power. The surface became smoother with shorter plasma exposure time and lower power. In addition, the plasma surface treatment was very efficient in removing the carbon contaminants on the silicon surface. The value of the initial surface energy, as estimated by using the crack propagation method, was 506 mJ/M sup 2 , which was up to about three times higher than the value for the conventional direct bonding method using wet chemical treatments.

Enhanced CO2 Adsorption on Activated Carbon Fibers Grafted with Nitrogen-Doped Carbon Nanotubes

Directory of Open Access Journals (Sweden)

Yu-Chun Chiang

2017-05-01

Full Text Available In this paper, multiscale composites formed by grafting N-doped carbon nanotubes (CNs on the surface of polyamide (PAN-based activated carbon fibers (ACFs were investigated and their adsorption performance for CO2 was determined. The spaghetti-like and randomly oriented CNs were homogeneously grown onto ACFs. The pre-immersion of cobalt(II ions for ACFs made the CNs grow above with a large pore size distribution, decreased the oxidation resistance, and exhibited different predominant N-functionalities after chemical vapor deposition processes. Specifically, the CNs grafted on ACFs with or without pre-immersion of cobalt(II ions were characterized by the pyridine-like structures of six-member rings or pyrrolic/amine moieties, respectively. In addition, the loss of microporosity on the specific surface area and pore volume exceeded the gain from the generation of the defects from CNs. The adsorption capacity of CO2 decreased gradually with increasing temperature, implying that CO2 adsorption was exothermic. The adsorption capacities of CO2 at 25 °C and 1 atm were between 1.53 and 1.92 mmol/g and the Freundlich equation fit the adsorption data well. The isosteric enthalpy of adsorption, implying physical adsorption, indicated that the growth of CNTs on the ACFs benefit CO2 adsorption.

Ammonia-treated porous carbon derived from ZIF-8 for enhanced CO{sub 2} adsorption

Energy Technology Data Exchange (ETDEWEB)

Ma, Xiancheng [School of Energy Science and Engineering, Central South University, Changsha 410083, Hunan (China); Li, Liqing, E-mail: liqingli@hotmail.com [School of Energy Science and Engineering, Central South University, Changsha 410083, Hunan (China); Wang, Shaobin [Department of Chemical Engineering, Curtin University, GPO Box U1987, Perth 6845, WA (Australia); Lu, Mingming [Department of Civil and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221 (United States); Li, Hailong; Ma, Weiwu [School of Energy Science and Engineering, Central South University, Changsha 410083, Hunan (China); Keener, Tim C. [Department of Civil and Environmental Engineering, University of Cincinnati, Cincinnati, OH 45221 (United States)

2016-04-30

Graphical abstract: The role of nitrogen species in increasing CO{sub 2} adsorption capacity has been explained with the mechanisms of base–acid interaction, as well as hydrogen bonds interaction. - Highlights: • A porous carbon (ZC) was prepared at 900 °C using ZIF-8 as a solid template for CO{sub 2} adsorption. • The ZC was further treated by ammonia functionalization to improve CO{sub 2} uptake. • The detailed interaction mechanism between N-containing groups and CO{sub 2} molecules is elucidated. - Abstract: A porous carbon (ZC) was prepared at 900 °C using zeolitic imidazolate framework-8 (ZIF-8) as a solid template for CO{sub 2} adsorption. The ZC was further treated by ammonia functionalization to improve CO{sub 2} uptake. The textural and surface characteristics of ZC samples were determined by X-ray diffraction (XRD), N{sub 2} adsorption, Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). It was revealed that ammonia treatment at 600 °C considerably enhanced the specific surface area and N-content of ZC. However, the pyrrolic-N group was decreased, yet the pyridinic-N group was increased with an increased temperature. The pyrrolic-N significantly enhanced CO{sub 2} adsorption. The ammonia treatment, on the one hand, increases the alkalinity of ZC sample and the base–acid interaction between N-containing functional groups with CO{sub 2}. On the other hand, the ammonia treatment increased pyrrolic-N group (NH) into carbon surface facilitating the hydrogen-bonding interactions between proton of pyrrolic-N and CO{sub 2} molecules.

Note: A single-chamber tool for plasma activation and surface functionalization in microfabrication

Energy Technology Data Exchange (ETDEWEB)

Bowman, Adam J.; Scherrer, Joseph R.; Reiserer, Ronald S., E-mail: ron.reiserer@vanderbilt.edu [Vanderbilt Institute for Integrative Biosystems Research and Education and Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)

2015-06-15

We present a simple apparatus for improved surface modification of polydimethylsiloxane (PDMS) microfluidic devices. A single treatment chamber for plasma activation and chemical/physical vapor deposition steps minimizes the time-dependent degradation of surface activation that is inherent in multi-chamber techniques. Contamination and deposition irregularities are also minimized by conducting plasma activation and treatment phases in the same vacuum environment. An inductively coupled plasma driver allows for interchangeable treatment chambers. Atomic force microscopy confirms that silane deposition on PDMS gives much better surface quality than standard deposition methods, which yield a higher local roughness and pronounced irregularities in the surface.

An alternative laser driven photodissociation mechanism of pyrrole via πσ*1∕S0 conical intersection.

Science.gov (United States)

Nandipati, K R; Lan, Z; Singh, H; Mahapatra, S

2017-06-07

A first principles quantum dynamics study of N-H photodissociation of pyrrole on the S 0 - 1 πσ * (A21) coupled electronic states is carried out with the aid of an optimally designed UV-laser pulse. A new photodissociation path, as compared to the conventional barrier crossing on the πσ*1 state, opens up upon electronic transitions under the influence of pump-dump laser pulses, which efficiently populate both the dissociation channels. The interplay of electronic transitions due both to vibronic coupling and the laser pulse is observed in the control mechanism and discussed in detail. The proposed control mechanism seems to be robust, and not discussed in the literature so far, and is expected to trigger future experiments on the πσ*1 photochemistry of molecules of chemical and biological importance. The design of the optimal pulses and their application to enhance the overall dissociation probability is carried out within the framework of optimal control theory. The quantum dynamics of the system in the presence of pulse is treated by solving the time-dependent Schrödinger equation in the semi-classical dipole approximation.

Atmospheric-pressure plasma activation and surface characterization on polyethylene membrane separator

Science.gov (United States)

Tseng, Yu-Chien; Li, Hsiao-Ling; Huang, Chun

2017-01-01

The surface hydrophilic activation of a polyethylene membrane separator was achieved using an atmospheric-pressure plasma jet. The surface of the atmospheric-pressure-plasma-treated membrane separator was found to be highly hydrophilic realized by adjusting the plasma power input. The variations in membrane separator chemical structure were confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Chemical analysis showed newly formed carbonyl-containing groups and high surface concentrations of oxygen-containing species on the atmospheric-pressure-plasma-treated polymeric separator surface. It also showed that surface hydrophilicity primarily increased from the polar component after atmospheric-pressure plasma treatment. The surface and pore structures of the polyethylene membrane separator were examined by scanning electron microscopy, revealing a slight alteration in the pore structure. As a result of the incorporation of polar functionalities by atmospheric-pressure plasma activation, the electrolyte uptake and electrochemical impedance of the atmospheric-pressure-plasma-treated membrane separator improved. The investigational results show that the separator surface can be controlled by atmospheric-pressure plasma surface treatment to tailor the hydrophilicity and enhance the electrochemical performance of lithium ion batteries.

Muscle force output and electromyographic activity in squats with various unstable surfaces.

Science.gov (United States)

Saeterbakken, Atle H; Fimland, Marius S

2013-01-01

The purpose of the study was to compare force output and muscle activity of leg and trunk muscles in isometric squats executed on stable surface (i.e., floor), power board, BOSU ball, and balance cone. Fifteen healthy men (23.3 ± 2.7 years, mass: 80.5 ± 8.5 kg, height: 1.81 ± 0.09 m) volunteered. The force output and electromyographic (EMG) activities of the rectus femoris, vastus medialis, vastus lateralis, biceps femoris, soleus, rectus abdominis, oblique external, and erector spinae were assessed. The order of the surfaces was randomized. One familiarization session was executed before the experimental test. Compared with stable surface (749 ± 222 N), the force output using power board was similar (-7%, p = 0.320) but lower for BOSU ball (-19%, p = 0.003) and balance cone (-24%, p ≤ 0.001). The force output using BOSU ball and balance cone was approximately 13% (p = 0.037) and approximately 18% (p = 0.001) less than the power board. There were similar EMG activities between the surfaces in all muscles except for rectus femoris, in which stable squat provided greater EMG activity than did the other exercises (p = 0.004-0.030). Lower EMG activity was observed in the rectus femoris using balance cone compared with the BOSU ball (p = 0.030). In conclusion, increasing the instability of the surface during maximum effort isometric squats usually maintains the muscle activity of lower-limb and superficial trunk muscles although the force output is reduced. This suggests that unstable surfaces in the squat may be beneficial in rehabilitation and as a part of periodized training programs, because similar muscle activity can be achieved with reduced loads.

Comparative study on the copper activation and xanthate adsorption on sphalerite and marmatite surfaces

Science.gov (United States)

Liu, Jian; Wang, Yu; Luo, Deqiang; Chen, Luzheng; Deng, Jiushuai

2018-05-01

The copper activation and potassium butyl xanthate (PBX) adsorption on sphalerite and marmatite surfaces were comparatively investigated using in situ local electrochemical impedance spectroscopy (LEIS), time-of-flight secondary ion mass spectrometry (ToF-SIMS) and surface adsorption tests. Comparing the LEIS and surface adsorption results, it was found that the activation time is a key factor influencing the copper activation and PBX adsorption on marmatite surface, but it has a negligible influence on sphalerite. For a short activation time within 10 min, the Fe impurity in marmatite shows an adverse influence on the speed of Cu adsorption and ion exchange as well as on the subsequent PBX adsorption. For a long activation time of 30 min, the LEIS, ToF-SIMS and surface adsorption results suggested that the Fe impurity in marmatite enhances the copper adsorption, whereas such enhanced copper adsorption of marmatite cannot result in corresponding enhancing of PBX adsorption. DFT result showed that the Fe impurity in marmatite has harmful influence on the PBX interaction with the Cu-activated surface by increasing the interaction energy. ToF-SIMS result further indicated that the Cu distribution in the outermost surface of marmatite is less than that of the sphalerite, which also results in the less PBX adsorption for the marmatite.

Linear response theory of activated surface diffusion with interacting adsorbates

Energy Technology Data Exchange (ETDEWEB)

Marti' nez-Casado, R. [Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ (United Kingdom); Sanz, A.S.; Vega, J.L. [Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 123, 28006 Madrid (Spain); Rojas-Lorenzo, G. [Instituto Superior de Tecnologi' as y Ciencias Aplicadas, Ave. Salvador Allende, esq. Luaces, 10400 La Habana (Cuba); Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cienti' ficas, Serrano 123, 28006 Madrid (Spain); Miret-Artes, S., E-mail: s.miret@imaff.cfmac.csic.es [Instituto de Fi' sica Fundamental, Consejo Superior de Investigaciones Cienti' ficas, Serrano 123, 28006 Madrid (Spain)

2010-05-12

Graphical abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed. - Abstract: Activated surface diffusion with interacting adsorbates is analyzed within the Linear Response Theory framework. The so-called interacting single adsorbate model is justified by means of a two-bath model, where one harmonic bath takes into account the interaction with the surface phonons, while the other one describes the surface coverage, this leading to defining a collisional friction. Here, the corresponding theory is applied to simple systems, such as diffusion on flat surfaces and the frustrated translational motion in a harmonic potential. Classical and quantum closed formulas are obtained. Furthermore, a more realistic problem, such as atomic Na diffusion on the corrugated Cu(0 0 1) surface, is presented and discussed within the classical context as well as within the framework of Kramer's theory. Quantum corrections to the classical results are also analyzed and discussed.

Influence of activated carbon characteristics on toluene and hexane adsorption: Application of surface response methodology

Science.gov (United States)

Izquierdo, Mª Teresa; de Yuso, Alicia Martínez; Valenciano, Raquel; Rubio, Begoña; Pino, Mª Rosa

2013-01-01

The objective of this study was to evaluate the adsorption capacity of toluene and hexane over activated carbons prepared according an experimental design, considering as variables the activation temperature, the impregnation ratio and the activation time. The response surface methodology was applied to optimize the adsorption capacity of the carbons regarding the preparation conditions that determine the physicochemical characteristics of the activated carbons. The methodology of preparation produced activated carbons with surface areas and micropore volumes as high as 1128 m2/g and 0.52 cm3/g, respectively. Moreover, the activated carbons exhibit mesoporosity, ranging from 64.6% to 89.1% the percentage of microporosity. The surface chemistry was characterized by TPD, FTIR and acid-base titration obtaining different values of surface groups from the different techniques because the limitation of each technique, but obtaining similar trends for the activated carbons studied. The exhaustive characterization of the activated carbons allows to state that the measured surface area does not explain the adsorption capacity for either toluene or n-hexane. On the other hand, the surface chemistry does not explain the adsorption results either. A compromise between physical and chemical characteristics can be obtained from the appropriate activation conditions, and the response surface methodology gives the optimal activated carbon to maximize adsorption capacity. Low activation temperature, intermediate impregnation ratio lead to high toluene and n-hexane adsorption capacities depending on the activation time, which a determining factor to maximize toluene adsorption.

Microstructure and surface properties of lignocellulosic-based activated carbons

Science.gov (United States)

González-García, P.; Centeno, T. A.; Urones-Garrote, E.; Ávila-Brande, D.; Otero-Díaz, L. C.

2013-01-01

Low cost activated carbons have been produced via chemical activation, by using KOH at 700 °C, from the bamboo species Guadua Angustifolia and Bambusa Vulgaris Striata and the residues from shells of the fruits of Castanea Sativa and Juglans Regia as carbon precursors. The scanning electron microscopy micrographs show the conservation of the precursor shape in the case of the Guadua Angustifolia and Bambusa Vulgaris Striata activated carbons. Transmission electron microscopy analyses reveal that these materials consist of carbon platelet-like particles with variable length and thickness, formed by highly disordered graphene-like layers with sp2 content ≈ 95% and average mass density of 1.65 g/cm3 (25% below standard graphite). Textural parameters indicate a high porosity development with surface areas ranging from 850 to 1100 m2/g and average pore width centered in the supermicropores range (1.3-1.8 nm). The electrochemical performance of the activated carbons shows specific capacitance values at low current density (1 mA/cm2) as high as 161 F/g in the Juglans Regia activated carbon, as a result of its textural parameters and the presence of pseudocapacitance derived from surface oxygenated acidic groups (mainly quinones and ethers) identified in this activated carbon.

Adsorption characteristics of N-nitrosodimethylamine from aqueous solution on surface-modified activated carbons

Energy Technology Data Exchange (ETDEWEB)

Xiaodong, Dai [Chemistry and Chemical Engineering School, China University of Petroleum, Dongying 257061, Shandong (China); Institute for Sustainability and Innovation, Victoria University, Melbourne, VIC 8001 (Australia); Zou, Linda [SA Water Centre for Water Management and Reuse, University of South Australia, Adelaide, SA5095 (Australia); Zifeng, Yan [Chemistry and Chemical Engineering School, China University of Petroleum, Dongying 257061, Shandong (China); Millikan, Mary [Institute for Sustainability and Innovation, Victoria University, Melbourne, VIC 8001 (Australia)

2009-08-30

This study investigated the removal of N-nitrosodimethylamine (NDMA) by an adsorption mechanism using commercially available activated carbons and surface-modified activated carbons. The effects of the modification on the properties of the activated carbon were studied by N{sub 2} adsorption/desorption, Diffuse Reflectance Infrared Fourier Transmission (DRIFT) analysis and X-Ray Photoelectron Spectroscopy (XPS). Adsorption experiments revealed that the activated carbons demonstrated a greater capacity for NDMA adsorption capacity than can be achieved using zeolite. The equilibrium data was fitted to the Freundlich equation and it was found that the adsorption capacity was significantly influenced by the micropore size, relative pore volume and surface characteristics. Adsorption experiments were conducted using unmodified and modified activated carbons. The results indicated that the adsorption capacity of NDMA can be significantly improved by heat treatment and doping of TiO{sub 2} particles. This was because the surface treatments yielded more hydrophobic sites and fewer oxygen-containing surface functional groups, and consequently an increased capacity for NDMA adsorption.

Adsorption characteristics of N-nitrosodimethylamine from aqueous solution on surface-modified activated carbons

International Nuclear Information System (INIS)

Dai Xiaodong; Zou, Linda; Yan Zifeng; Millikan, Mary

2009-01-01

This study investigated the removal of N-nitrosodimethylamine (NDMA) by an adsorption mechanism using commercially available activated carbons and surface-modified activated carbons. The effects of the modification on the properties of the activated carbon were studied by N 2 adsorption/desorption, Diffuse Reflectance Infrared Fourier Transmission (DRIFT) analysis and X-Ray Photoelectron Spectroscopy (XPS). Adsorption experiments revealed that the activated carbons demonstrated a greater capacity for NDMA adsorption capacity than can be achieved using zeolite. The equilibrium data was fitted to the Freundlich equation and it was found that the adsorption capacity was significantly influenced by the micropore size, relative pore volume and surface characteristics. Adsorption experiments were conducted using unmodified and modified activated carbons. The results indicated that the adsorption capacity of NDMA can be significantly improved by heat treatment and doping of TiO 2 particles. This was because the surface treatments yielded more hydrophobic sites and fewer oxygen-containing surface functional groups, and consequently an increased capacity for NDMA adsorption.

Measurements of radon progeny activity on typical indoor surfaces

International Nuclear Information System (INIS)

Knutson, E.O.; Gogolak, C.V.; Klemic, G.

1992-01-01

A number of studies aimed at defining how well radon progeny on surfaces can be measured, information that is needed in order to test physical/mathematical models governing indoor radon progeny behaviour, are described. One experiment compared the decomposition on to different surfaces. Only relatively small differences were found among metal, filter paper, broadcloth, corduroy fabric, vinyl wallpaper, glass, and latex paint, but polyethylene film collected two to four times as much as the others, due most likely to electrostatic charge on the plastic surface. Another experiment compared the gamma and gross alpha count methods of measuring surface activity for metal, filter paper, broadcloth and corduroy surfaces. No difference for the surfaces tested was found from which it is concluded that, even for rougher surfaces, progeny atoms deposit mainly on the outer layers. A final experiment compared in situ and surrogate-surface methods for measuring surface deposition. For most tests, the two methods agreed within 30%, and the average ratio was not significantly different from unity. 210 Po is a complication in the in situ method. An unexpected location effect was found in the experiments conducted in houses with high radon concentrations: the deposition on the ceiling was higher than on the surfaces. (author)

A description of the BNL active surface analysis facility

International Nuclear Information System (INIS)

Tyler, J.W.

1989-11-01

Berkeley Nuclear Laboratories has a responsibility for the assessment of radioactive specimens arising both from post irradiation examination of power reactor components and structures and experimental programmes concerned with fission and activation product transport. Existing analytical facilities have been extended with the commissioning of an active surface analysis instrument (XSAM 800pci, Kratos Analytical). Surface analysis involves the characterisation of the outer few atomic layers of a solid surface/interface whose chemical composition and electronic structure will probably be different from the bulk. The new instrument consists three interconnected chambers positioned in series; comprising of a high vacuum sample introduction chamber, an ultra-high vacuum sample treatment/fracture chamber and an ultra-high vacuum sample analysis chamber. The sample analysis chamber contains the electron, X-ray and ion-guns and the electron and ion detectors necessary for performing X-ray photoelectron spectroscopy, scanning Auger microscopy and secondary-ion mass spectroscopy. The chamber also contains a high stability manipulator to enable sub-micron imaging of specimens to be achieved and provide sample heating and cooling between - 180 and 600 0 C. (author)

Evaluation of antituberculosis activity and DFT study on dipyrromethane-derived hydrazone derivatives

Science.gov (United States)

Rawat, Poonam; Singh, R. N.; Niranjan, Priydarshni; Ranjan, Alok; Holguín, Norma Rosario Flores

2017-12-01

This paper evaluates the anti-tubercular activity of dipyrromethane-derived hydrazones derivatives (3a-d) against strain of Mycobacterium tuberculosis H37Rv. The newly synthesized compounds have been obtained in good yield based on the condensation of aromatic aldehyde derivatives with pyrrole hydrazone in presence of catalyst and well characterized with spectroscopic methods (1H, 13C NMR, Mass spectrometry) and elemental analysis. The singlet observed in the experimental 1H and 13C NMR spectra in the range of 5.3-5.7 ppm and 30-33.86 ppm, respectively, indicating that two pyrrole units are joined at meso position. The electronic transitions observed in the experimental spectra are n→π* and π →π* in nature. Experimental and theoretical findings corroborate well with each other. The substitution of acceptor group (-NO2) at ortho- and meta-positions of benzene ring, present at meso-position of dipyrromethane is responsible for variation in β0 values. The calculated NLO of (3a-d) are much greater than those of p-nitroaniline (PNA). The solvent induced effects on the non-linear optical properties were studied and found to enhance NLO properties of the molecules as dielectric constants of the solvents increases. On the basis of results it is anticipated that these dipyrromethanes will be useful for both antimicrobial and non-linear optical (NLO) applications. With the help of Microplate Alamar Blue assay (MABA) method all (3a-d) compounds were screened for their anti-tubercular activity and found that 3b and 3d have higher inhibitory activity against strain of M. tuberculosis H37Rv.

Surface sediment quality relative to port activities: A contaminant-spectrum assessment.

Science.gov (United States)

Yu, Shen; Hong, Bing; Ma, Jun; Chen, Yongshan; Xi, Xiuping; Gao, Jingbo; Hu, Xiuqin; Xu, Xiangrong; Sun, Yuxin

2017-10-15

Ports are facing increasing environmental concerns with their importance to the global economy. Numerous studies indicated sediment quality deterioration in ports; however, the deterioration is not discriminated for each port activity. This study investigated a spectrum of contaminants (metals and organic pollutants) in surface sediments at 20 sampling points in Port Ningbo, China, one of the top five world ports by volume. The spectrum of contaminants (metals and organic pollutants) was quantified following marine sediment quality guidelines of China and USA and surface sediment quality was assessed according to thresholds of the two guidelines. Coupling a categorical matrix of port activities with the matrix of sedimentary contaminants revealed that contaminants were highly associated with the port operations. Ship repair posed a severe chemical risk to sediment. Operations of crude oil and coal loadings were two top activities related to organic pollutants in sediments while port operations of ore and container loadings discharged metals. Among the 20 sampling points, Cu, Zn, Pb, and DDT and its metabolites were the priority contaminants influencing sediment quality. Overall, surface sediments in Port Ningbo had relatively low environmental risks but ship repair is an environmental concern that must be addressed. This study provides a practical approach for port activity-related quality assessment of surface sediments in ports that could be applicable in many world sites. Copyright © 2017 Elsevier B.V. All rights reserved.

In-situ Studies of the Reactions of Bifunctional and Heterocyclic Molecules over Noble Metal Single Crystal and Nanoparticle Catalysts Studied with Kinetics and Sum-Frequency Generation Vibrational Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Kliewer, Christopher J. [Univ. of California, Berkeley, CA (United States)

2009-06-30

Sum frequency generation surface vibrational spectroscopy (SFG-VS) in combination with gas chromatography (GC) was used in-situ to monitor surface bound reaction intermediates and reaction selectivities for the hydrogenation reactions of pyrrole, furan, pyridine, acrolein, crotonaldehyde, and prenal over Pt(111), Pt(100), Rh(111), and platinum nanoparticles under Torr reactant pressures and temperatures of 300K to 450K. The focus of this work is the correlation between the SFG-VS observed surface bound reaction intermediates and adsorption modes with the reaction selectivity, and how this is affected by catalyst structure and temperature. Pyrrole hydrogenation was investigated over Pt(111) and Rh(111) single crystals at Torr pressures. It was found that pyrrole adsorbs to Pt(111) perpendicularly by cleaving the N-H bond and binding through the nitrogen. However, over Rh(111) pyrrole adsorbs in a tilted geometry binding through the {pi}-aromatic orbitals. A surface-bound pyrroline reaction intermediate was detected over both surfaces with SFG-VS. It was found that the ring-cracking product butylamine is a reaction poison over both surfaces studied. Furan hydrogenation was studied over Pt(111), Pt(100), 10 nm cubic platinum nanoparticles and 1 nm platinum nanoparticles. The product distribution was observed to be highly structure sensitive and the acquired SFG-VS spectra reflected this sensitivity. Pt(100) exhibited more ring-cracking to form butanol than Pt(111), while the nanoparticles yielded higher selectivities for the partially saturated ring dihydrofuran. Pyridine hydrogenation was investigated over Pt(111) and Pt(100). The α-pyridyl surface adsorption mode was observed with SFG-VS over both surfaces. 1,4-dihydropyridine was seen as a surface intermediate over Pt(100) but not Pt(111). Upon heating the surfaces to 350K, the adsorbed pyridine changes to a flat-lying adsorption mode. No evidence was found for the pyridinium cation. The hydrogenation of the �

Optimized preparation for large surface area activated carbon from date (Phoenix dactylifera L.) stone biomass

International Nuclear Information System (INIS)

Danish, Mohammed; Hashim, Rokiah; Ibrahim, M.N. Mohamad; Sulaiman, Othman

2014-01-01

The preparation of activated carbon from date stone treated with phosphoric acid was optimized using rotatable central composite design of response surface methodology (RSM). The chemical activating agent concentration and temperature of activation plays a crucial role in preparation of large surface area activated carbons. The optimized activated carbon was characterized using thermogravimetric analysis, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, powder X-ray diffraction, and Fourier transform infrared spectroscopy. The results showed that the larger surface area of activated carbon from date stone can be achieved under optimum activating agent (phosphoric acid) concentration, 50.0% (8.674 mol L −1 ) and activation temperature, 900 °C. The Brunauer–Emmett–Teller (BET) surface area of optimized activated carbon was found to be 1225 m 2  g −1 , and thermogravimetric analysis revealed that 55.2% mass of optimized activated carbon was found thermally stable till 900 °C. The leading chemical functional groups found in the date stone activated carbon were aliphatic carboxylic acid salt ν(C=O) 1561.22 cm −1 and 1384.52 cm −1 , aliphatic hydrocarbons ν(C–H) 2922.99 cm −1 (C–H sym./asym. stretch frequency), aliphatic phosphates ν(P–O–C) 1054.09 cm −1 , and secondary aliphatic alcohols ν(O–H) 3419.81 cm −1 and 1159.83 cm −1 . - Highlights: • RSM optimization was done for the production of large surface area activated carbon. • Two independent variables with two responses were selected for optimization. • Characterization was done for surface area, morphology and chemical constituents. • Optimized date stone activated carbon achieved surface area 1225 m 2  g −1

Predicting the minimum liquid surface tension activity of pseudomonads expressing biosurfactants.

Science.gov (United States)

Mohammed, I U; Deeni, Y; Hapca, S M; McLaughlin, K; Spiers, A J

2015-01-01

Bacteria produce a variety of biosurfactants capable of significantly reducing liquid (aqueous) surface tension (γ) with a range of biological roles and biotechnological uses. To determine the lowest achievable surface tension (γMin ), we tested a diverse collection of Pseudomonas-like isolates from contaminated soil and activated sludge and identified those expressing biosurfactants by drop-collapse assay. Liquid surface tension-reducing ability was quantitatively determined by tensiometry, with 57 isolates found to significantly lower culture supernatant surface tensions to 24·5-49·1 mN m(-1) . Differences in biosurfactant behaviour determined by foaming, emulsion and oil-displacement assays were also observed amongst isolates producing surface tensions of 25-27 mN m(-1) , suggesting that a range of structurally diverse biosurfactants were being expressed. Individual distribution identification (IDI) analysis was used to identify the theoretical probability distribution that best fitted the surface tension data, which predicted a γMin of 24·24 mN m(-1) . This was in agreement with predictions based on earlier work of published mixed bacterial spp. data, suggesting a fundamental limit to the ability of bacterial biosurfactants to reduce surface tensions in aqueous systems. This implies a biological restriction on the synthesis and export of these agents or a physical-chemical restriction on their functioning once produced. Numerous surveys of biosurfactant-producing bacteria have been conducted, but only recently has an attempt been made to predict the minimum liquid surface tension these surface-active agents can achieve. Here, we determine a theoretical minimum of 24 mN m(-1) by statistical analysis of tensiometry data, suggesting a fundamental limit for biosurfactant activity in bacterial cultures incubated under standard growth conditions. This raises a challenge to our understanding of biosurfactant expression, secretion and function, as well as

The Comparative Study on Vapor-Polymerization and Pressure-dependent Conductance Behavior in Polypyrrole-hybridized Membranes

Energy Technology Data Exchange (ETDEWEB)

Hanif, Zahid; Lee, Seyeong; Arsalani, Nasir; Geckeler, Kurt E.; Hong, Sukwon; Yoon, Myung-Han [Gwangju Institute of Science and Technology, Gwangju (Korea, Republic of)

2016-02-15

In this study, commercially available cellulose membranes were hybridized with conjugated polymer via vapor-phase polymerization using pyrrole and iron chloride as a monomer and oxidant, respectively. The iron (III) chloride layer dip-coated on the hydrophilic cell ulose surface oxidized the vaporized pyrrole monomer leading to the polypyrrole-cellulose hybrid membrane. The conductivity of hybrid membrane was optimized by varying the oxidant concentration and the monomer vapor exposure time. The various surface characterizations of polypyrrole-cellulose hybrid membrane show that the conductive polypyrrole layer was uniformly deposited onto the surface of cellulose fibrous networks unlike the polypyrrole-nylonhybrid membrane prepared in the similar way. The polypyrrole-incorporated cellulose networks exhibits steeper electrical conductance increase over the vertical pressure than its nylon counterpart. Our result suggests that the polypyrrole-cellulose hybrid membrane can be applicable for a disposable high-load pressure sensor.

The Comparative Study on Vapor-Polymerization and Pressure-dependent Conductance Behavior in Polypyrrole-hybridized Membranes

International Nuclear Information System (INIS)

Hanif, Zahid; Lee, Seyeong; Arsalani, Nasir; Geckeler, Kurt E.; Hong, Sukwon; Yoon, Myung-Han

2016-01-01

In this study, commercially available cellulose membranes were hybridized with conjugated polymer via vapor-phase polymerization using pyrrole and iron chloride as a monomer and oxidant, respectively. The iron (III) chloride layer dip-coated on the hydrophilic cell ulose surface oxidized the vaporized pyrrole monomer leading to the polypyrrole-cellulose hybrid membrane. The conductivity of hybrid membrane was optimized by varying the oxidant concentration and the monomer vapor exposure time. The various surface characterizations of polypyrrole-cellulose hybrid membrane show that the conductive polypyrrole layer was uniformly deposited onto the surface of cellulose fibrous networks unlike the polypyrrole-nylonhybrid membrane prepared in the similar way. The polypyrrole-incorporated cellulose networks exhibits steeper electrical conductance increase over the vertical pressure than its nylon counterpart. Our result suggests that the polypyrrole-cellulose hybrid membrane can be applicable for a disposable high-load pressure sensor.

Effects of Lignosulfonate Structure on the Surface Activity and Wettability to a Hydrophobic Powder

Directory of Open Access Journals (Sweden)

Yuanyuan Ge

2014-10-01

Full Text Available The wettability of a solid material is very important in many applications, such as food, agrochemical formulations, and cosmetics. Wettability can be improved by adding surface active agents, especially biocompatible surfactants derived from biomass. In this work, the surface activity (ability to lower the surface tension of an aqueous solution and wettability toward a hydrophobic powder by a series of sodium lignosulfonates (NaLS synthesized with different degree of sulfonation (QS and weight-average molecular weights (Mw were investigated by measuring the surface tension and contact angle. The results demonstrated NaLS with a larger Mw or lower QS had higher surface activity. Conversely, the wettability of the NaLS aqueous solution toward difenoconazole powder showed a reverse trend, i.e., NaLS with a smaller Mw or higher Qs improved the wettability to difenoconazole. The surface activity and wettability was controlled by the varying densities of the NaLS molecules at the water to air interface or the solid/liquid interface, which was dependent on the molecular structure of NaLS.

Biochemical studies on certain biologically active nitrogenous compounds

International Nuclear Information System (INIS)

Abdel kader, S.M.; El Sayed, M.M.; El Malt, E.A.; Shaker, E.S.; Abdel Aziz, H.G.

2010-01-01

Certain biologically active nitrogenous compounds such as alkaloids are widely distributed in many wild and medicinal plants such as peganum harmala L. (Phycophyllaceae). However, less literature cited on the natural compounds was extracted from the aerial parts of this plant; therefore this study was conducted on harmal leaves using several solvents. Data indicated that methanol extract was the inhibitoriest effect against some pathogenic bacteria, particularly Streptococcus pyogenus. Chromatographic separation illustrated that presence of four compounds; the most active one was the third compound (3). Elementary analysis (C, H, N) revealed that the primary chemical structure of the active antibacterial compound (C3) was: C17 H21 N3 O7 S with molecular weight 411. Spectroscopic analysis proved that coninical structure was = 1- thioformyl, 8?- D glucoperanoside- Bis- 2, 3 dihydroisopyridino pyrrol. This new compound is represented as a noval ?- carboline alkaloid compound

Immunoassay approach for diagnosis of exposure to pyrrolizidine alkaloids.

Science.gov (United States)

Li, Na; Zhang, Fan; Lian, Wei; Wang, Huali; Zheng, Jiang; Lin, Ge

2017-07-03

Numerous pyrrolizidine alkaloid (PA) poisoning cases have been documented worldwide. Protein covalent binding with reactive metabolites generated from metabolic activation of PAs to form pyrrole-protein adducts is suggested to be a primary mechanism of PA-induced toxicities. The present study aimed to develop antibodies for diagnosis of PA exposure. Polyclonal antibodies were raised in rabbits and proven to specifically recognize pyrrole-protein adducts regardless of amino acid residues modified by the reactive metabolites of PAs. The developed antibodies were successfully applied to detect pyrrole-protein adducts in blood samples obtained from PA-treated rats and exhibited a potential for the clinical diagnosis of PA exposure.

Preparation and characterization of high surface area activated carbon from Fox nut (Euryale ferox shell by chemical activation with H3PO4

Directory of Open Access Journals (Sweden)

Arvind Kumar

Full Text Available Activated carbons were prepared from Fox nutshell by chemical activation with H3PO4 in N2 atmosphere and their characteristics were studied. The effects of activation temperature and impregnation ratio were examined. N2 adsorption isotherms characterized the surface area, total pore volume, micropore volume and pore size distribution of activated carbons. Activated carbon was produced at 700 °C with a 1.5 impregnation ratio and one hour of activation time has found 2636 m2/g and 1.53 cm3/g of highest BET surface area and total pore volume, respectively. The result of Fourier-infrared spectroscopy analysis of the prepared activated carbon confirmed that the carbon has abundant functional groups on the surface. Field emission scanning electron micrographs of the prepared activated carbon showed that a porous structure formed during activation. Keywords: Activated carbons, Fox nutshell, Chemical activation, H3PO4, Activated carbon, Surface chemistry, Porous structure

Does Titan have an Active Surface?

Science.gov (United States)

Nelson, R.

2009-12-01

ammonia, a compound expected in Titan’s interior. This, combined with the previous evidence from VIMS and RADAR images, creates a strong case for Titan having a presently active surface, possibly due to cryovolcanism. Cassini encountered Titan at very close range on 2008-11-19-13:58 and again on 2008-12-05-12:38. These epochs are called T47 and T48. Comparison of earlier lower resolution data (T5) with the recent T47 and T48 data reveal changes of the surface reflectance and morphology in the Hotei region. This is the first evidence from VIMS that confirms the RADAR report that Hotei Reggio has morphology consistent with volcanic terrain. It has not escaped our attention that ammonia, in association with methane and nitrogen, the principal species of Titan’s atmosphere, closely replicates the environment at the time that live first emerged on earth. If Titan is currently active then these results raise the following questions: What is the full extent of current geologic activity? What are the ongoing processes? Are Titan’s chemical processes today supporting a prebiotic chemistry similar to that under which life evolved on Earth? This work done at JPL under contract with NASA. Refs: [1]R. M. Nelson et al., Icarus 199 (2009) 429-441. [2]R. M. Nelson et al., GRL, VOL. 36, L04202, doi:10.1029/2008GL036206, 2009. [3]S. D. Wall GRL, VOL. 36, L04203, doi:10.1029/2008GL036415, 2009

Surface modification, characterization and adsorptive properties of a coconut activated carbon

Energy Technology Data Exchange (ETDEWEB)

Lu Xincheng [Institute of Chemical Industry of Forest Products, CAF, National Engineering Lab. for Biomass Chemical Utilization, Key and Open Lab. of Forest Chemical Engineering, SFA, Key Lab. of Biomass Energy and Material, Jiangsu Province, Suojin wucun 16, Nanjing 210042 (China); Jiang Jianchun, E-mail: lhs_ac2011@yahoo.cn [Institute of Chemical Industry of Forest Products, CAF, National Engineering Lab. for Biomass Chemical Utilization, Key and Open Lab. of Forest Chemical Engineering, SFA, Key Lab. of Biomass Energy and Material, Jiangsu Province, Suojin wucun 16, Nanjing 210042 (China); Sun Kang; Xie Xinping; Hu Yiming [Institute of Chemical Industry of Forest Products, CAF, National Engineering Lab. for Biomass Chemical Utilization, Key and Open Lab. of Forest Chemical Engineering, SFA, Key Lab. of Biomass Energy and Material, Jiangsu Province, Suojin wucun 16, Nanjing 210042 (China)

2012-08-01

A coconut activated carbon was modified using chemical methods. Different concentration of nitric acid oxidation of the conventional sample produced samples with weakly acidic functional groups. The oxidized samples were characterized by scanning electron micrograph, nitrogen absorption-desorption, Fourier transform infra red spectroscopy, Bothem method, pH titration, adsorption capacity of sodium and formaldehyde, and the adsorption mechanism of activated carbons was investigated. The results showed that BET surface area and pore volume of activated carbons were decreased after oxidization process, while acidic functional groups were increased. The surface morphology of oxidized carbons looked clean and eroded which was caused by oxidization of nitric acid. The oxidized carbons showed high adsorption capacity of sodium and formaldehyde, and chemical properties of activated carbon played an important role in adsorption of metal ions and organic pollutants.

Passivation of phosphorus diffused silicon surfaces with Al2O3: Influence of surface doping concentration and thermal activation treatments

International Nuclear Information System (INIS)

Richter, Armin; Benick, Jan; Kimmerle, Achim; Hermle, Martin; Glunz, Stefan W.

2014-01-01

Thin layers of Al 2 O 3 are well known for the excellent passivation of p-type c-Si surfaces including highly doped p + emitters, due to a high density of fixed negative charges. Recent results indicate that Al 2 O 3 can also provide a good passivation of certain phosphorus-diffused n + c-Si surfaces. In this work, we studied the recombination at Al 2 O 3 passivated n + surfaces theoretically with device simulations and experimentally for Al 2 O 3 deposited with atomic layer deposition. The simulation results indicate that there is a certain surface doping concentration, where the recombination is maximal due to depletion or weak inversion of the charge carriers at the c-Si/Al 2 O 3 interface. This pronounced maximum was also observed experimentally for n + surfaces passivated either with Al 2 O 3 single layers or stacks of Al 2 O 3 capped by SiN x , when activated with a low temperature anneal (425 °C). In contrast, for Al 2 O 3 /SiN x stacks activated with a short high-temperature firing process (800 °C) a significant lower surface recombination was observed for most n + diffusion profiles without such a pronounced maximum. Based on experimentally determined interface properties and simulation results, we attribute this superior passivation quality after firing to a better chemical surface passivation, quantified by a lower interface defect density, in combination with a lower density of negative fixed charges. These experimental results reveal that Al 2 O 3 /SiN x stacks can provide not only excellent passivation on p + surfaces but also on n + surfaces for a wide range of surface doping concentrations when activated with short high-temperature treatments

Developments of a bonding technique for optical materials by a surface activation method

International Nuclear Information System (INIS)

Sugiyama, Akira; Oda, Tomohiro; Abe, Tomoyuki; Kusunoki, Isao

2007-01-01

We have been developing a pair of sample holder used for optics in the surface activation bonding equipment. The holder can adjust the relative position of samples in the order of sub mm. To study the degree of dislocation appearing crystal surface activated by a fast atomic beam, irradiated sapphire crystals were examined by RBS, XPS, and AFM analysis. The heat treatment recovered the surface roughness of irradiated sapphire when the heating temperature reached at 1573 K. (author)

Performance limitations in thieno[3,4-c]pyrrole-4,6-dione-based polymer:ITIC solar cells

KAUST Repository

Yang, Fan

2017-08-15

We report a systematic study of the efficiency limitations of non-fullerene organic solar cells that exhibit a small energy loss (Eloss) between the polymer donor and the non-fullerene acceptor. To clarify the impact of Eloss on the performance of the solar cells, three thieno[3,4-c]pyrrole-4,6-dione-based conjugated polymers (PTPD3T, PTPD2T, and PTPDBDT) are employed as the electron donor, which all have complementary absorption spectra compared with the ITIC acceptor. The corresponding photovoltaic devices show that low Eloss (0.54 eV) in PTPDBDT:ITIC leads to a high open-circuit voltage (Voc) of 1.05 V, but also to a small quantum efficiency, and in turn photocurrent. The high Voc or small energy loss in the PTPDBDT-based solar cells is a consequence of less non-radiative recombination, whereas the low quantum efficiency is attributed to the unfavorable micro-phase separation, as confirmed by the steady-state and time-resolved photoluminescence experiments, grazing-incidence wide-angle X-ray scattering, and resonant soft X-ray scattering (R-SoXS) measurements. We conclude that to achieve high performance non-fullerene solar cells, it is essential to realize a large Voc with small Eloss while simultaneously maintaining a high quantum efficiency by manipulating the molecular interaction in the bulk-heterojunction.

Performance limitations in thieno[3,4-c]pyrrole-4,6-dione-based polymer:ITIC solar cells

KAUST Repository

Yang, Fan; Qian, Deping; Balawi, Ahmed Hesham; Wu, Yang; Ma, Wei; Laquai, Fré dé ric; Tang, Zheng; Zhang, Fengling; Li, Weiwei

2017-01-01

We report a systematic study of the efficiency limitations of non-fullerene organic solar cells that exhibit a small energy loss (Eloss) between the polymer donor and the non-fullerene acceptor. To clarify the impact of Eloss on the performance of the solar cells, three thieno[3,4-c]pyrrole-4,6-dione-based conjugated polymers (PTPD3T, PTPD2T, and PTPDBDT) are employed as the electron donor, which all have complementary absorption spectra compared with the ITIC acceptor. The corresponding photovoltaic devices show that low Eloss (0.54 eV) in PTPDBDT:ITIC leads to a high open-circuit voltage (Voc) of 1.05 V, but also to a small quantum efficiency, and in turn photocurrent. The high Voc or small energy loss in the PTPDBDT-based solar cells is a consequence of less non-radiative recombination, whereas the low quantum efficiency is attributed to the unfavorable micro-phase separation, as confirmed by the steady-state and time-resolved photoluminescence experiments, grazing-incidence wide-angle X-ray scattering, and resonant soft X-ray scattering (R-SoXS) measurements. We conclude that to achieve high performance non-fullerene solar cells, it is essential to realize a large Voc with small Eloss while simultaneously maintaining a high quantum efficiency by manipulating the molecular interaction in the bulk-heterojunction.

The surface activity of purified ocular mucin at the air-liquid interface and interactions with meibomian lipids.

Science.gov (United States)

Millar, Thomas J; Tragoulias, Sophia T; Anderton, Philip J; Ball, Malcolm S; Miano, Fausto; Dennis, Gary R; Mudgil, Poonam

2006-01-01

Ocular mucins are thought to contribute to the stability of the tear film by reducing surface tension. The purpose of this study was to compare the effect of different mucins and hyaluronic acid (HA) alone and mixed with meibomian lipids on the surface pressure at an air-liquid interface. A Langmuir trough and Wilhelmy balance were used to measure and compare the surface activity of bovine submaxillary gland mucin (BSM), purified BSM, purified bovine ocular mucin and HA, and mixtures of these with meibomian lipids, phosphatidylcholine, and phosphatidylglycerol. Their appearance at the surface of an air-buffer interface was examined using epifluorescence microscopy. Purified ocular mucin had no surface activity even at concentrations that were 100 times more than normally occur in tears. By contrast, commercial BSM caused changes to surface pressure that were concentration dependent. The surface pressure-area profiles showed surface activity with maximum surface pressures of 12.3-22.5 mN/m depending on the concentration. Purified BSM showed no surface activity at low concentrations, whereas higher concentrations reached a maximum surface pressure of 25 mN/m. HA showed no surface activity, at low or high concentrations. Epifluorescence showed that the mucins were located at the air-buffer interface and changed the appearance of lipid films. Purified bovine ocular mucin and HA have no surface activity. However, despite having no surface activity in their own right, ocular mucins are likely to be present at the surface of the tear film, where they cause an increase in surface pressure by causing a compression of the lipids (a reorganization of the lipids) and alter the viscoelastic properties at the surface.

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.

Polymerization by plasma: surface treatment and plasma simulation

International Nuclear Information System (INIS)

Morales C, J.

2001-01-01

One of the general objectives that are developed by the group of polymers semiconductors in the laboratory of polymers of the UAM-Iztapalapa is to study the surface treatment for plasma of different materials. Framed in this general objective, in this work three lines of investigation have been developed, independent one of other that converge in the general objective. The first one tries about the modeling one and evaluation of the microscopic parameters of operation of the polymerization reactor. The second are continuation of the study of conductive polymers synthesized by plasma and the third are an application of the treatment for plasma on natural fibers. In the first one it lines it is carried out the characterization and simulation of the parameters of operation of the polymerization reactor for plasma. They are determined the microscopic parameters of operation of the reactor experimentally like they are the electronic temperature, the potential of the plasma and the density average of electrons using for it an electrostatic Langmuir probe. In the simulation, starting from the Boltzmann transport equation it thinks about the flowing pattern and the electronic temperature, the ions density is obtained and of electrons. The data are compared obtained experimentally with the results of the simulation. In second line a study is presented about the influence of the temperature on the electric conductivity of thin films doped with iodine, of poly aniline (P An/I) and poly pyrrole (P Py/I). The films underwent heating-cooling cycles. The conductivity of P An/I and P Py/I in function of the temperature it is discussed based on the Arrhenius model, showing that it dominates the model of homogeneous conductivity. It is also synthesized a polymer bi-layer of these two elements and a copolymer random poly aniline-poly pyrrole, of the first one it the behavior of its conductivity discusses with the temperature and of the second, the conductivity is discussed in

Sensing surface mechanical deformation using active probes driven by motor proteins

Science.gov (United States)

Inoue, Daisuke; Nitta, Takahiro; Kabir, Arif Md. Rashedul; Sada, Kazuki; Gong, Jian Ping; Konagaya, Akihiko; Kakugo, Akira

2016-01-01

Studying mechanical deformation at the surface of soft materials has been challenging due to the difficulty in separating surface deformation from the bulk elasticity of the materials. Here, we introduce a new approach for studying the surface mechanical deformation of a soft material by utilizing a large number of self-propelled microprobes driven by motor proteins on the surface of the material. Information about the surface mechanical deformation of the soft material is obtained through changes in mobility of the microprobes wandering across the surface of the soft material. The active microprobes respond to mechanical deformation of the surface and readily change their velocity and direction depending on the extent and mode of surface deformation. This highly parallel and reliable method of sensing mechanical deformation at the surface of soft materials is expected to find applications that explore surface mechanics of soft materials and consequently would greatly benefit the surface science. PMID:27694937

Isolation, screening, and characterization of surface-active agent-producing, oil-degrading marine bacteria of Mumbai Harbor.

Science.gov (United States)

Mohanram, Rajamani; Jagtap, Chandrakant; Kumar, Pradeep

2016-04-15

Diverse marine bacterial species predominantly found in oil-polluted seawater produce diverse surface-active agents. Surface-active agents produced by bacteria are classified into two groups based on their molecular weights, namely biosurfactants and bioemulsifiers. In this study, surface-active agent-producing, oil-degrading marine bacteria were isolated using a modified Bushnell-Haas medium with high-speed diesel as a carbon source from three oil-polluted sites of Mumbai Harbor. Surface-active agent-producing bacterial strains were screened using nine widely used methods. The nineteen bacterial strains showed positive results for more than four surface-active agent screening methods; further, these strains were characterized using biochemical and nucleic acid sequencing methods. Based on the results, the organisms belonged to the genera Acinetobacter, Alcanivorax, Bacillus, Comamonas, Chryseomicrobium, Halomonas, Marinobacter, Nesterenkonia, Pseudomonas, and Serratia. The present study confirmed the prevalence of surface-active agent-producing bacteria in the oil-polluted waters of Mumbai Harbor. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of high surface area activated carbon on thermal degradation of jet fuel

Energy Technology Data Exchange (ETDEWEB)

Gergova, K.; Eser, S.; Arumugam, R.; Schobert, H.H. [Pennsylvania State Univ., University Park, PA (United States)

1995-05-01

Different solid carbons added to jet fuel during thermal stressing cause substantial changes in pyrolytic degradation reactions. Activated carbons, especially high surface area activated carbons were found to be very effective in suppressing solid deposition on metal reactor walls during stressing at high temperatures (425 and 450{degrees}C). The high surface area activated carbon PX-21 prevented solid deposition on reactor walls even after 5h at 450{degrees}C. The differences seen in the liquid product composition when activated carbon is added indicated that the carbon surfaces affect the degradation reactions. Thermal stressing experiments were carried out on commercial petroleum-derived JPTS jet fuel. We also used n-octane and n-dodecane as model compounds in order to simplify the study of the chemical changes which take place upon activated carbon addition. In separate experiments, the presence of a hydrogen donor, decalin, together with PX-21 was also studied.

Developments of a bonding technique for optical materials by a surface activation method

International Nuclear Information System (INIS)

Sugiyama, Akira; Oda, Tomohiro; Abe, Tomoyuki; Kusunoki, Isao

2005-01-01

We started developing the laser crystal bounding by the surface activation method which can splice crystals together without using hydrogen bonding. For the surface activation, neutral argon beams were used for irradiation of specimens. In the bonding trials with sapphire crystals, we recognized possibility of the bonding method for optical elements. (author)

A thermal spike analysis of low energy ion activated surface processes

International Nuclear Information System (INIS)

Gilmore, G.M.; Haeri, A.; Sprague, J.A.

1989-01-01

This paper reports a thermal spike analysis utilized to predict the time evolution of energy propagation through a solid resulting from energetic particle impact. An analytical solution was developed that can predict the number of surface excitations such as desorption, diffusion or chemical reaction activated by an energetic particle. The analytical solution is limited to substrates at zero Kelvin and to materials with constant thermal diffusivities. These limitations were removed by developing a computer numerical integration of the propagation of the thermal spike through the solid and the subsequent activation of surface processes

Corrosion properties of the Mg alloy coated with polypyrrole films

International Nuclear Information System (INIS)

Grubač, Zoran; Rončević, Ivana Škugor; Metikoš-Huković, Mirjana

2016-01-01

Highlights: • Electropolymerization of pyrrole on Mg-alloy surface in presence of salicylate. • Salicylate dual role in PPy deposition: passivation and electron transfer mediation. • Redox potential of salicylate corresponds to potential of PPy nucleation. • EIS and polarization corrosion studies of PPy coated Mg-alloy in Hanks’ solution. • Polypyrrole significantly slowdown Mg alloy corrosion in Hanks’ solution. - Abstract: In the present study the reactive surface of Mg alloy was coated with the nontoxic biocompatible polypyrrole (PPy) film synthesized by electrochemical oxidation from an aqueous salicylate solution. Salicylate ions prevent Mg dissolution and act as an electron transfer mediator during the PPy film nucleation, formation and growth on the alloy surface. Kinetics of the pyrrole polymerization as well as corrosion resistance of the PPy coated Mg alloy in the Hanks’ solution were investigated using dc electrochemical methods and electrochemical impedance spectroscopy (EIS). Characterization of the surface film was performed by optical and Fourier transform infrared spectroscopy (FTIR).

Competitive Adsorption between Nanoparticles and Surface Active Ions for the Oil-Water Interface.

Science.gov (United States)

Hua, Xiaoqing; Bevan, Michael A; Frechette, Joelle

2018-04-24

Nanoparticles (NPs) can add functionality (e.g., catalytic, optical, rheological) to an oil-water interface. Adsorption of ∼10 nm NPs can be reversible; however, the mechanisms for adsorption and its effects on surface pressure remain poorly understood. Here we demonstrate how the competitive reversible adsorption of NPs and surfactants at fluid interfaces can lead to independent control of both the adsorbed amount and surface pressure. In contrast to prior work, both species investigated (NPs and surfactants) interact reversibly with the interface and without the surface active species binding to NPs. Independent measurements of the adsorption and surface pressure isotherms allow determination of the equation of state (EOS) of the interface under conditions where the NPs and surfactants are both in dynamic equilibrium with the bulk phase. The adsorption and surface pressure measurements are performed with gold NPs of two different sizes (5 and 10 nm), at two pH values, and across a wide concentration range of surfactant (tetrapentylammonium, TPeA + ) and NPs. We show that free surface active ions compete with NPs for the interface and give rise to larger surface pressures upon the adsorption of NPs. Through a competitive adsorption model, we decouple the contributions of NPs wetting at the interface and their surface activity on the measured surface pressure. We also demonstrate reversible control of adsorbed amount via changes in the surfactant concentration or the aqueous phase pH.

Influence of nitrogen surface functionalities on the catalytic activity of activated carbon in low temperature SCR of NOx with NH3

International Nuclear Information System (INIS)

Szymanski, Grzegorz S.; Grzybek, Teresa; Papp, Helmut

2004-01-01

The reduction of nitrogen oxide with ammonia was studied using carbon catalysts with chemically modified surfaces. Carbon samples with different surface chemistry were obtained from commercial activated carbon D43/1 (CarboTech, Essen, Germany) by chemical modification involving oxidation with conc. nitric acid (DOx) (1); high temperature treatment (=1000K) under vacuum (DHT) (2); or in ammonia (DHTN, DOxN) (3). Additionally, a portion of the DOx sample was promoted with iron(III) ions (DOxFe). The catalytic tests were performed in a microreactor at a temperature range of 413-573K. The carbon sample annealed under vacuum (DHT) showed the lowest activity. The formation of surface acidic surface oxides by nitric acid treatment (DOx) enhanced the catalytic activity only slightly. However, as can be expected, subsequent promotion of the DOx sample with iron(III) ions increased drastically its catalytic activity. However, this was accompanied by some loss of selectivity, i.e. formation of N 2 O as side product. This effect can be avoided using ammonia-treated carbons which demonstrated reasonable activity with simultaneous high selectivity. The most active and selective among them was the sample that was first oxidized with nitric acid and then heated in an ammonia stream (DOxN). A correlation between catalytic activity and surface nitrogen content was observed. Surface nitrogen species seem to play an important role in catalytic selective reduction of nitrogen oxide with ammonia, possibly facilitating NO 2 formation (a reaction intermediate) as a result of easier chemisorption of oxygen and nitrogen oxide

MICROORGANISMS’ SURFACE ACTIVE SUBSTANCES ROLE IN HYDROCARBONS BIODEGRADATION

Directory of Open Access Journals (Sweden)

Оlga Vasylchenko

2012-09-01

Full Text Available  Existing data and publications regarding oil, hydrocarbon biodegradation, metabolism, and bioremediation were analyzed. Search of hydrocarbon degrading bacteria which are producers of biosurfactants was provided, types of microbial surfactants and their physiological role were analyzed and ordered. The study of factors affecting the surface active properties of producers’ cultures was done.

Surface-Bound Ligands Modulate Chemoselectivity and Activity of a Bimetallic Nanoparticle Catalyst

KAUST Repository

Vu, Khanh B.

2015-04-03

"Naked" metal nanoparticles (NPs) are thermodynamically and kinetically unstable in solution. Ligands, surfactants, or polymers, which adsorb at a particle\\'s surface, can be used to stabilize NPs; however, such a mode of stabilization is undesirable for catalytic applications because the adsorbates block the surface active sites. The catalytic activity and the stability of NPs are usually inversely correlated. Here, we describe an example of a bimetallic (PtFe) NP catalyst stabilized by carboxylate surface ligands that bind preferentially to one of the metals (Fe). NPs stabilized by fluorous ligands were found to be remarkably competent in catalyzing the hydrogenation of cinnamaldehyde; NPs stabilized by hydrocarbon ligands were significantly less active. The chain length of the fluorous ligands played a key role in determining the chemoselectivity of the FePt NP catalysts. (Chemical Presented). © 2015 American Chemical Society.

Radiotracer studies of the adsorption of surface active substances at aqueous surfaces, 6

International Nuclear Information System (INIS)

Tajima, Kazuo

1976-01-01

The surface tension and adsorption were observed by the Wilhelmy plate and radiotracer methods at the air-solution interface of an aqueous solution of urea and α-dodecyl-ω-hydroxyhexa(oxyethylene) (D(EO) 6 ). The adsorption of D(EO) 6 was dependent on the concentration of urea below the CMC values, but above the values it was independent of the concentration. Urea adsorption occurs positively for low-surface packing of the poly(oxyethylene) group of D(EO) 6 , but negatively for the closest packing of the group and high concentrations of urea. It was confirmed that D(EO) 6 adsorption took place at the solution surface according to the Gibbs adsorption isotherm, which was taken into account as an activity coefficient in an empirical equation for the interactions of D(EO) 6 and urea in solution. Urea adsorption for the adsorbed monolayer of D(EO) 6 above the CMC value was interpreted assuming that urea, as for the nonionic micelle, was nonpenetrating, which was examined by gel permeation. (auth.)

Synthesis, surface properties and antimicrobial activity of some germanium nonionic surfactants.

Science.gov (United States)

Zaki, Mohamed F; Tawfik, Salah M

2014-01-01

Esterification reaction between different fatty acid namely; lauric, stearic, oleic and linoleic acids and polyethylene glycol-400 were performed. The produced polyethylene glycol ester were reacted with p-amine benzoic acid followed by condensation reaction with germanium dioxide in presence of sodium carbonate to form desired germinate surfactants. The chemical structures of the synthesized surfactants were determined using different spectra tools. The surface parameter including: the critical micelle concentration (CMC), effectiveness (π(cmc)), efficiency (Pc20), maximum surface excess (Γ(max)) and minimum surface area (A(min)), were calculated from the surface tension measurements. The synthesized surfactants showed higher surface activity. The thermodynamic parameters showed that adsorption and micellization processes are spontaneous. It is clear that the synthesized nonionic surfactants showed their tendency towards adsorption at the interfaces and also micellization in the bulk of their solutions. The synthesized surfactants were tested against different strain of bacteria using inhibition zone diameters. The synthesized surfactants showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative as well as fungi. The promising inhibition efficiency of these compounds against the sulfate reducing bacteria facilitates them to be applicable as new categories of sulfate reducing bacteria biocides.

High surface enhanced Raman scattering activity of BN nanosheets–Ag nanoparticles hybrids

International Nuclear Information System (INIS)

Yang, Shanshan; Zhang, Zhaochun; Zhao, Jun; Zheng, Houli

2014-01-01

Highlights: • Boron nitride–silver nanohybrid was acquired through a liquid-phase reducing route. • The composite shown a high-quality SERS activity. • 2-Mercaptobenzimidazole was chemisorbed on silver surface in vertical orientation. -- Abstract: A facile liquid-phase reducing route was developed to modify boron nitride (BN) nanosheets with silver nanoparticles (AgNPs) in order to fabricate BN–AgNPs hybrids with high surface enhanced Raman scattering (SERS) activity. The layered structure and morphology of BN–AgNPs nanohybrids were characterized by transmission electron microscopy and atomic force microscopy, meanwhile, Fourier transform infrared spectroscopy and ultraviolet–visible were used for studying optical properties and surface plasmon resonance applied to the optical sensor. The SERS of adsorbed 2-mercaptobenzimidazole (MBI) molecule was investigated which shown that the BN–AgNPs substrate exhibited a very strong SERS activity, offering a great potential application in molecular probe sensor. On the basis of the analysis of SERS and the Raman surface selection rules, we could draw a conclusion that the MBI molecule was adsorbed upright on the AgNPs surface through the sulphur and nitrogen atoms. What is more, the cyclic voltammetry experiment indicated the electrochemically irreversible behavior of BN–AgNPs nanohybrids in KCl solution

The synthesis of Ag/polypyrrole coaxial nanocables via ion adsorption method using different oxidants

Science.gov (United States)

Qiu, Teng; Xie, Huxiao; Zhang, Jiangru; Zahoor, Amad; Li, Xiaoyu

2011-03-01

Ag/polypyrrole (PPy) coaxial nanocables (NCs) were synthesized by an ion adsorption method. In this method, the pre-made Ag nanowires (NWs) were dispersed in the aqueous solution of copper acetate (Cu(Ac)2), and the Cu2+ ions adsorbed onto the surface of Ag NWs can oxidize pyrrole monomers to polymerize into uniform PPy sheath outside Ag NWs after the Cu(Ac)2-treated Ag NWs were re-dispersed in the aqueous solution of pyrrole. The morphology of NCs was characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). The relationship between the thickness of polymer sheath and the concentration of Cu(Ac)2 was established. As Cu(Ac)2 which served as the oxidant can also be replaced by AgNO3 in this synthesis, the differences on the structure of polymer sheath caused by different oxidants were studied by surface-enhanced Raman scattering (SERS), high-resolution transmission electron microscope (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Comparing with the characterization results of Ag/PPy NCs synthesized using AgNO3 as the oxidant which indicates the random arrangement of PPy chains at the interface between polymer sheath and Ag NWs, PPy chain oxidized by Cu2+ tends to show a relatively ordered conformation at the interface with the pyrrole rings identically taking the plane vertical to the surface of Ag NWs. In addition, although the main part of the polymer sheath was composed of PPy whatever kind of oxidant was used, the sheath of the NCs oxidized by Cu2+ is typical for the existence of Cu(I)-pyrrole coordinate structures with strong Cu(I)-N bond signal shown in XPS characterization.

The synthesis of Ag/polypyrrole coaxial nanocables via ion adsorption method using different oxidants

International Nuclear Information System (INIS)

Qiu Teng; Xie Huxiao; Zhang Jiangru; Zahoor, Amad; Li Xiaoyu

2011-01-01

Ag/polypyrrole (PPy) coaxial nanocables (NCs) were synthesized by an ion adsorption method. In this method, the pre-made Ag nanowires (NWs) were dispersed in the aqueous solution of copper acetate (Cu(Ac) 2 ), and the Cu 2+ ions adsorbed onto the surface of Ag NWs can oxidize pyrrole monomers to polymerize into uniform PPy sheath outside Ag NWs after the Cu(Ac) 2 -treated Ag NWs were re-dispersed in the aqueous solution of pyrrole. The morphology of NCs was characterized by transmission electron microscope (TEM) and scanning electron microscope (SEM). The relationship between the thickness of polymer sheath and the concentration of Cu(Ac) 2 was established. As Cu(Ac) 2 which served as the oxidant can also be replaced by AgNO 3 in this synthesis, the differences on the structure of polymer sheath caused by different oxidants were studied by surface-enhanced Raman scattering (SERS), high-resolution transmission electron microscope (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Comparing with the characterization results of Ag/PPy NCs synthesized using AgNO 3 as the oxidant which indicates the random arrangement of PPy chains at the interface between polymer sheath and Ag NWs, PPy chain oxidized by Cu 2+ tends to show a relatively ordered conformation at the interface with the pyrrole rings identically taking the plane vertical to the surface of Ag NWs. In addition, although the main part of the polymer sheath was composed of PPy whatever kind of oxidant was used, the sheath of the NCs oxidized by Cu 2+ is typical for the existence of Cu(I)–pyrrole coordinate structures with strong Cu(I)–N bond signal shown in XPS characterization.

Surface characteristics and antibacterial activity of a silver-doped carbon monolith

Directory of Open Access Journals (Sweden)

Marija Vukčević et al

2008-01-01

Full Text Available A carbon monolith with a silver coating was prepared and its antimicrobial behaviour in a flow system was examined. The functional groups on the surface of the carbon monolith were determined by temperature-programmed desorption and Boehm's method, and the point of zero charge was determined by mass titration. The specific surface area was examined by N2 adsorption using the Brunauer, Emmett and Teller (BET method. As a test for the surface activity, the deposition of silver from an aqueous solution of a silver salt was used. The morphology and structure of the silver coatings were characterized by scanning electron microscopy and x-ray diffraction. The resistance to the attrition of the silver deposited on the carbon monolith was tested. The antimicrobial activity of the carbon monolith with a silver coating was determined using standard microbiological methods. Carbon monolith samples with a silver coating showed good antimicrobial activity against Escherichia coli, Staphylococcus aureus and Candida albicans, and are therefore suitable for water purification, particularly as personal disposable water filters with a limited capacity.

Surface grafting of zwitterionic polymers onto dye doped AIE-active luminescent silica nanoparticles through surface-initiated ATRP for biological imaging applications

Science.gov (United States)

Mao, Liucheng; Liu, Xinhua; Liu, Meiying; Huang, Long; Xu, Dazhuang; Jiang, Ruming; Huang, Qiang; Wen, Yuanqing; Zhang, Xiaoyong; Wei, Yen

2017-10-01

Aggregation-induced emission (AIE) dyes have recently been intensively explored for biological imaging applications owing to their outstanding optical feature as compared with conventional organic dyes. The AIE-active luminescent silica nanoparticles (LSNPs) are expected to combine the advantages both of silica nanoparticles and AIE-active dyes. Although the AIE-active LSNPs have been prepared previously, surface modification of these AIE-active LSNPs with functional polymers has not been reported thus far. In this work, we reported a rather facile and general strategy for preparation of polymers functionalized AIE-active LSNPs through the surface-initiated atom transfer radical polymerization (ATRP). The AIE-active LSNPs were fabricated via direct encapsulation of AIE-active dye into silica nanoparticles through a non-covalent modified Stöber method. The ATRP initiator was subsequently immobilized onto these AIE-active LSNPs through amidation reaction between 3-aminopropyl-triethoxy-silane and 2-bromoisobutyryl bromide. Finally, the zwitterionic 2-(methacryloyloxy)ethyl phosphorylcholine (MPC) was selected as model monomer and grafted onto MSNs through ATRP. The characterization results suggested that LSNPs can be successfully modified with poly(MPC) through surface-initiated ATRP. The biological evaluation results demonstrated that the final SNPs-AIE-pMPC composites possess low cytotoxicity, desirable optical properties and great potential for biological imaging. Taken together, we demonstrated that AIE-active LSNPs can be fabricated and surface modified with functional polymers to endow novel functions and better performance for biomedical applications. More importantly, this strategy developed in this work could also be extended for fabrication of many other LSNPs polymer composites owing to the good monomer adoptability of ATRP.

Active-site titration analysis of surface influence on immobilized Candida antarctica Lipase B activity

Science.gov (United States)

Matrix morphology and surface polarity effects were investigated for Candida antarctica lipase B immobilization. Measurements of the amount of lipase immobilized (bicinchoninic acid method) and the catalyst’s tributyrin hydrolysis activity, coupled with a determination of the lipase’s functional fr...

Non-Covalent Functionalisation of C30 Fullerene by Pyrrole-n-Carboxylic Acid (n=2, 3): Density Functional Theory Studies

Science.gov (United States)

Harismah, Kun; Mirzaei, Mahmoud; Ghasemi, Nahid; Nejati, Mohammad

2017-12-01

For functionalisation of a representative C30 fullerene nanostructure by pyrrole-n-carboxylic acid (PnCA; n=2, 3) their stabilities and properties were investigated based on density functional theory calculations. Parallel calculations were also done for C60 fullerene as evidence for comparing the results. Non-covalent interactions are considered to make the functionalised structures. In contrast with the spherical shape of C60, the shape of C30 fullerene is elliptical; therefore, the functionalisation processes were done for both axial and equatorial elliptical positions (AC30 and EC30). The results indicated that both the positions of C30 have almost equivalent chances to be functionalised by PnCA; but functionalisation by P2CA is slightly more favourable than P3CA, either for C60. The illustrated molecular orbitals' distributions indicated that the direction of charge transfer could be considered from PnCA counterparts to fullerene counterparts. The molecular properties indicated more reactivity for C30 than for C60 fullerene. Finally, the atomic scale quadrupole coupling constants indicated different roles for N and O atoms of PnCA in the functionalised models.

Stochastic Description of Activated Surface Diffusion with Interacting Adsorbates

Science.gov (United States)

Martínez-Casado, Ruth; Vega, José Luis; Sanz, Ángel S.; Miret-Artés, Salvador

Activated surface diffusion on metal surfaces is receiving much attention both experimentally and theoretically. One of the main theoretical problems in this field is to explain the line-shape broadening observed when the surface coverage is increased. Recently, we have proposed a fully stochastic model, the interacting single adsorbate (ISA) model, aimed at explaining and understanding this type of experiments, which essentially consists of considering the classical Langevin formulation with two types of noise forces: (i) a Gaussian white noise accounting for the substrate friction, and (ii) a shot noise simulating the interacting adsorbates at different coverages. No interaction potential between adsorbates is included because any trace of microscopic interaction seems to be wiped out in a Markovian regime. This model describes in a good approximation, and at a very low computational cost, the line-shape broadening observed experimentally. Furthermore, its mathematical simplicity also allows to derive some analytical expressions which are of much help in the interpretation of the physics underlying surface diffusion processes.

Effect of sulfation on the surface activity of CaO for N2O decomposition

International Nuclear Information System (INIS)

Wu, Lingnan; Hu, Xiaoying; Qin, Wu; Dong, Changqing; Yang, Yongping

2015-01-01

Graphical abstract: - Highlights: • Sulfation of CaO (1 0 0) surface greatly deactivates its surface activity for N 2 O decomposition. • An increase of sulfation degree leads to a decrease of CaO surface activity for N 2 O decomposition. • Sulfation from CaSO 3 into CaSO 4 is the crucial step for deactivating the surface activity for N 2 O decomposition. • The electronic interaction CaO (1 0 0)/CaSO 4 (0 0 1) interface is limited to the bottom layer of CaSO 4 (0 0 1) and the top layer of CaO (1 0 0). • CaSO 4 (0 0 1) and (0 1 0) surfaces show negligible catalytic ability for N 2 O decomposition. - Abstract: Limestone addition to circulating fluidized bed boilers for sulfur removal affects nitrous oxide (N 2 O) emission at the same time, but mechanism of how sulfation process influences the surface activity of CaO for N 2 O decomposition remains unclear. In this paper, we investigated the effect of sulfation on the surface properties and catalytic activity of CaO for N 2 O decomposition using density functional theory calculations. Sulfation of CaO (1 0 0) surface by the adsorption of a single gaseous SO 2 or SO 3 molecule forms stable local CaSO 3 or CaSO 4 on the CaO (1 0 0) surface with strong hybridization between the S atom of SO x and the surface O anion. The formed local CaSO 3 increases the barrier energy of N 2 O decomposition from 0.989 eV (on the CaO (1 0 0) surface) to 1.340 eV, and further sulfation into local CaSO 4 remarkably increases the barrier energy to 2.967 eV. Sulfation from CaSO 3 into CaSO 4 is therefore the crucial step for deactivating the surface activity for N 2 O decomposition. Completely sulfated CaSO 4 (0 0 1) and (0 1 0) surfaces further validate the negligible catalytic ability of CaSO 4 for N 2 O decomposition.

Surface strontium enrichment on highly active perovskites for oxygen electrocatalysis in solid oxide fuel cells

KAUST Repository

Crumlin, Ethan J.; Mutoro, Eva; Liu, Zhi; Grass, Michael E.; Biegalski, Michael D.; Lee, Yueh-Lin; Morgan, Dane; Christen, Hans M.; Bluhm, Hendrik; Shao-Horn, Yang

2012-01-01

Perovskite oxides have high catalytic activities for oxygen electrocatalysis competitive to platinum at elevated temperatures. However, little is known about the oxide surface chemistry that influences the activity near ambient oxygen partial pressures, which hampers the design of highly active catalysts for many clean-energy technologies such as solid oxide fuel cells. Using in situ synchrotron-based, ambient pressure X-ray photoelectron spectroscopy to study the surface chemistry changes, we show that the coverage of surface secondary phases on a (001)-oriented La 0.8Sr 0.2CoO 3-δ (LSC) film becomes smaller than that on an LSC powder pellet at elevated temperatures. In addition, strontium (Sr) in the perovskite structure enriches towards the film surface in contrast to the pellet having no detectable changes with increasing temperature. We propose that the ability to reduce surface secondary phases and develop Sr-enriched perovskite surfaces of the LSC film contributes to its enhanced activity for O 2 electrocatalysis relative to LSC powder-based electrodes. © 2012 The Royal Society of Chemistry.

SURFACE-ACTIVE PROPERTIES OF THE DISTILLERS GRAINS AND THE PECTINS ISOLATED FROM THEM

Directory of Open Access Journals (Sweden)

N. S. Kaisheva

2016-01-01

Full Text Available Distillers grains are a huge secondary raw material resource, prospective for different fields, including pharmaceutical use, because of a rich content of biologically active compounds. The purpose of this paper was to estimate possibilities of the pharmaceutical use of distillers grains as the additive agent by means of surface-active properties of distillers grains study as well as pectins, isolated from them. We have established the surface-active properties of the liquid phase of the distillers wheat grains by means of higher pressure of air bubbles with the use of Rehbinder’s apparatus. It contained 6.67 mol/m3 pectins, and pectins isolated from a solid phase of the same distillers grains: surface activity 11.67 and 7.54, saturated surface excess amounted to 1.28×10-5 and 6.25×10-5 mol/m2, critical concentration of micelle formation amounted to 1.32 mol/m3 and 1.48 mol/m3 respectively. Surface-active characteristics of distillers grains and isolated pectins are comparable with well-known natural polysaccharides (sodium alginate, polygalacturonic acid, beet bin pectin, which are used as additive agents in technology of medicinal plants. We have determined the sizes of pectins molecules from distillers grains in the unsaturated adsorption layers, which differed from the well-known polysaccharides by lesser square (2.658 Å2, radius (0.920 Å, diameter of cross-section (1.840 Å and the volume (2727 Å3 at the bigger mass per surface unit (1.031×10-4 кг and a length (1026 Å. The data obtained by the sizes of pectin molecules are the favorable factor, which conduced their high biological availability. 

Activities of the Vastus Lateralis and Vastus Medialis Oblique Muscles during Squats on Different Surfaces.

Science.gov (United States)

Hyong, In Hyouk; Kang, Jong Ho

2013-08-01

[Purpose] The purpose of the present study was to examine the effects of squat exercises performed on different surfaces on the activity of the quadriceps femoris muscle in order to provide information on support surfaces for effective squat exercises. [Subjects and Method] Fourteen healthy subjects performed squat exercises for five seconds each on three different support surfaces: hard plates, foam, and rubber air discs. Their performance was measured using electromyography. As the subjects performed the squat exercises on each surface, data on the activity of the vastus medialis oblique and the vastus lateralis, and the vastus medials oblique/vastus lateralis ratio, were collected. [Results] The activity of the vastus medialis oblique and the vastus medialis oblique/vastus lateralis ratio were found to be statistically significantly higher on rubber air discs than when the squats were performed on hard plates or foam. [Conclusion] To activate the vastus medialis obilique, and to enhance the vastus medialis oblique/vastus lateralis ratio, unstable surfaces that are highly unstable should be selected.

Simultaneous surface and depth neural activity recording with graphene transistor-based dual-modality probes.

Science.gov (United States)

Du, Mingde; Xu, Xianchen; Yang, Long; Guo, Yichuan; Guan, Shouliang; Shi, Jidong; Wang, Jinfen; Fang, Ying

2018-05-15

Subdural surface and penetrating depth probes are widely applied to record neural activities from the cortical surface and intracortical locations of the brain, respectively. Simultaneous surface and depth neural activity recording is essential to understand the linkage between the two modalities. Here, we develop flexible dual-modality neural probes based on graphene transistors. The neural probes exhibit stable electrical performance even under 90° bending because of the excellent mechanical properties of graphene, and thus allow multi-site recording from the subdural surface of rat cortex. In addition, finite element analysis was carried out to investigate the mechanical interactions between probe and cortex tissue during intracortical implantation. Based on the simulation results, a sharp tip angle of π/6 was chosen to facilitate tissue penetration of the neural probes. Accordingly, the graphene transistor-based dual-modality neural probes have been successfully applied for simultaneous surface and depth recording of epileptiform activity of rat brain in vivo. Our results show that graphene transistor-based dual-modality neural probes can serve as a facile and versatile tool to study tempo-spatial patterns of neural activities. Copyright © 2018 Elsevier B.V. All rights reserved.

New Concept of C–H and C–C Bond Activation via Surface Organometallic Chemistry

KAUST Repository

Samantaray, Manoja

2015-08-18

In this chapter we describe the recent applications of well-defined oxidesupported metal alkyls/alkylidenes/alkylidynes and hydrides of group IV, V, and VI transition metals in the field of C–H and C–C bond activation. The activation of ubiquitous C–H and C–C bonds of paraffin is a long-standing challenge because of intrinsic low reactivity. There are many concepts derived from surface organometallic chemistry (SOMC): surface organometallic fragments are always intermediates in heterogeneous catalysis. The study of their synthesis and reactivity is a way to rationalize mechanism of heterogeneous catalysis and to achieve structure activity relationship. By surface organometallic chemistry one can enter any catalytic center by a reaction intermediate leading in fine to single site catalysts. With surface organometallic chemistry one can coordinate to the metal which can play a role in different elementary steps leading for example to C–H activation and Olefin metathesis. Because of the development of SOMC there is a lot of space for the improvement of homogeneous catalysis. After the 1997 discovery of alkane metathesis using silica-supported tantalum hydride by Basset et al. at low temperature (150ºC) the focus in this area was shifted to the discovery of more and more challenging surface complexes active in the application of C–H and C–C bond activation. Here we describe the evolution of well-defined metathesis catalyst with time as well as the effect of support on catalysis. We also describe here which metal–ligand combinations are responsible for a variety of C–H and C–C bond activation.

Porous structure and surface chemistry of phosphoric acid activated carbon from corncob

Science.gov (United States)

Sych, N. V.; Trofymenko, S. I.; Poddubnaya, O. I.; Tsyba, M. M.; Sapsay, V. I.; Klymchuk, D. O.; Puziy, A. M.

2012-11-01

Active carbons have been prepared from corncob using chemical activation with phosphoric acid at 400 °C using varied ratio of impregnation (RI). Porous structure of carbons was characterized by nitrogen adsorption and scanning electron microscopy. Surface chemistry was studied by IR and potentiometric titration method. It has been shown that porosity development was peaked at RI = 1.0 (SBET = 2081 m2/g, Vtot = 1.1 cm3/g), while maximum amount of acid surface groups was observed at RI = 1.25. Acid surface groups of phosphoric acid activated carbons from corncob includes phosphate and strongly acidic carboxylic (pK = 2.0-2.6), weakly acidic carboxylic (pK = 4.7-5.0), enol/lactone (pK = 6.7-7.4; 8.8-9.4) and phenol (pK = 10.1-10.7). Corncob derived carbons showed high adsorption capacity to copper, especially at low pH. Maximum adsorption of methylene blue and iodine was observed for carbon with most developed porosity (RI = 1.0).

Sequence-selective single-molecule alkylation with a pyrrole-imidazole polyamide visualized in a DNA nanoscaffold.

Science.gov (United States)

Yoshidome, Tomofumi; Endo, Masayuki; Kashiwazaki, Gengo; Hidaka, Kumi; Bando, Toshikazu; Sugiyama, Hiroshi

2012-03-14

We demonstrate a novel strategy for visualizing sequence-selective alkylation of target double-stranded DNA (dsDNA) using a synthetic pyrrole-imidazole (PI) polyamide in a designed DNA origami scaffold. Doubly functionalized PI polyamide was designed by introduction of an alkylating agent 1-(chloromethyl)-5-hydroxy-1,2-dihydro-3H-benz[e]indole (seco-CBI) and biotin for sequence-selective alkylation at the target sequence and subsequent streptavidin labeling, respectively. Selective alkylation of the target site in the substrate DNA was observed by analysis using sequencing gel electrophoresis. For the single-molecule observation of the alkylation by functionalized PI polyamide using atomic force microscopy (AFM), the target position in the dsDNA (∼200 base pairs) was alkylated and then visualized by labeling with streptavidin. Newly designed DNA origami scaffold named "five-well DNA frame" carrying five different dsDNA sequences in its cavities was used for the detailed analysis of the sequence-selectivity and alkylation. The 64-mer dsDNAs were introduced to five individual wells, in which target sequence AGTXCCA/TGGYACT (XY = AT, TA, GC, CG) was employed as fully matched (X = G) and one-base mismatched (X = A, T, C) sequences. The fully matched sequence was alkylated with 88% selectivity over other mismatched sequences. In addition, the PI polyamide failed to attach to the target sequence lacking the alkylation site after washing and streptavidin treatment. Therefore, the PI polyamide discriminated the one mismatched nucleotide at the single-molecule level, and alkylation anchored the PI polyamide to the target dsDNA.

Exotic high activity surface patterns in PtAu nanoclusters

KAUST Repository

Mokkath, Junais Habeeb

2013-05-09

The structure and chemical ordering of PtAu nanoclusters of 79, 135, and 201 atoms are studied via a combination of a basin hopping atom-exchange technique (to locate the lowest energy homotops at fixed composition), a symmetry orbit technique (to find the high symmetry isomers), and density functional theory local reoptimization (for determining the most stable homotop). The interatomic interactions between Pt and Au are derived from the empirical Gupta potential. The lowest energy structures show a marked tendency toward PtcoreAushell chemical ordering by enrichment of the more cohesive Pt in the core region and of Au in the shell region. We observe a preferential segregation of Pt atoms to (111) facets and Au atoms to (100) facets of the truncated octahedron cluster motif. Exotic surface patterns are obtained particularly for Pt-rich compositions, where Pt atoms are being surrounded by Au atoms. These surface arrangements boost the catalytic activity by creating a large number of active sites. © 2013 American Chemical Society.

Biofabrication Using Pyrrole Electropolymerization for the Immobilization of Glucose Oxidase and Lactate Oxidase on Implanted Microfabricated Biotransducers

Directory of Open Access Journals (Sweden)

Christian N. Kotanen

2014-03-01

Full Text Available The dual responsive Electrochemical Cell-on-a-Chip Microdisc Electrode Array (ECC MDEA 5037 is a recently developed electrochemical transducer for use in a wireless, implantable biosensor system for the continuous measurement of interstitial glucose and lactate. Fabrication of the biorecognition membrane via pyrrole electropolymerization and both in vitro and in vivo characterization of the resulting biotransducer is described. The influence of EDC-NHS covalent conjugation of glucose oxidase with 4-(3-pyrrolyl butyric acid (monomerization and with 4-sulfobenzoic acid (sulfonization on biosensor performance was examined. As the extent of enzyme conjugation was increased sensitivity decreased for monomerized enzymes but increased for sulfonized enzymes. Implanted biotransducers were examined in a Sprague-Dawley rat hemorrhage model. Resection after 4 h and subsequent in vitro re-characterization showed a decreased sensitivity from 0.68 (±0.40 to 0.22 (±0.17 µA·cm−2·mM−1, an increase in the limit of detection from 0.05 (±0.03 to 0.27 (±0.27 mM and a six-fold increase in the response time from 41 (±18 to 244 (±193 s. This evidence reconfirms the importance of biofouling at the bio-abio interface and the need for mitigation strategies to address the foreign body response.

Fe-N{sub x}/C assisted chemical–mechanical polishing for improving the removal rate of sapphire

Energy Technology Data Exchange (ETDEWEB)

Xu, Li, E-mail: xl0522@126.com [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/Nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Zou, Chunli; Shi, Xiaolei [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/Nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Pan, Guoshun, E-mail: pangs@tsinghua.edu.cn [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/Nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China); Luo, Guihai; Zhou, Yan [State Key Laboratory of Tribology, Tsinghua University, Beijing 100084 (China); Shenzhen Key Laboratory of Micro/Nano Manufacturing, Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China)

2015-07-15

Highlights: • A novel non-noble metal catalyst (Fe-N{sub x}/C) was prepared. • Fe-N{sub x}/C shows remarkable catalytic activity for improving the removal rate of sapphire in alkaline solution. • The optimum CMP removal by Fe-N{sub x}/C yielded a superior surface finish of 0.078 nm the average roughness. • Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4}, pyridinic N as well as pyrrolic N group possibly serving as the catalytic sites. • A soft hydration layer (boehmite, AlO(OH)) was generated on the surface of sapphire during CMP process. - Abstract: In this paper, a novel non-noble metal catalyst (Fe-N{sub x}/C) is used to improve the removal mass of sapphire as well as obtain atomically smooth sapphire wafer surfaces. The results indicate that Fe-N{sub x}/C shows good catalytic activity towards sapphire removal rate. And the material removal rates (MRRs) are found to vary with the catalyst content in the polishing fluid. Especially that when the polishing slurry mixes with 16 ppm Fe-N{sub x}/C shows the maximum MRR and its removal mass of sapphire is 38.43 nm/min, more than 15.44% larger than traditional CMP using the colloidal silicon dioxide (SiO{sub 2}) without Fe-N{sub x}/C. Catalyst-assisted chemical–mechanical polishing of sapphire is studied with X-ray photoelectron spectroscopy (XPS). It is found that the formation of a soft hydration layer (boehmite, γ-AlOOH or γ-AlO(OH)) on sapphire surface facilitates the material removal and achieving fine surface finish on basal plane. Abrasives (colloid silica together with magnetite, ingredient of Fe-N{sub x}/C) with a hardness between boehmite and sapphire polish the c-plane of sapphire with good surface finish and efficient removal. Fe{sub 2}O{sub 3}, Fe{sub 3}O{sub 4}, pyridinic N as well as pyrrolic N group would be the catalytical active sites and accelerate this process. Surface quality is characterized with atomic force microscopy (AFM). The optimum CMP removal by Fe-N{sub x}/C also yields a superior

THE EFFECT OF ACTIVATED CARBON SURFACE MOISTURE ON LOW TEMPERATURE MERCURY ADSORPTION

Science.gov (United States)

Experiments with elemental mercury (Hg0) adsorption by activated carbons were performed using a bench-scale fixed-bed reactor at room temperature (27 degrees C) to determine the role of surface moisture in capturing Hg0. A bituminous-coal-based activated carbon (BPL) and an activ...

Selective radiolabeling of cell surface proteins to a high specific activity

International Nuclear Information System (INIS)

Thompson, J.A.; Lau, A.L.; Cunningham, D.D.

1987-01-01

A procedure was developed for selective radiolabeling of membrane proteins on cells to higher specific activities than possible with available techniques. Cell surface amino groups were derivatized with 125 I-(hydroxyphenyl)propionyl groups via 125 I-sulfosuccinimidyl (hydroxyphenyl)propionate ( 125 II-sulfo-SHPP). This reagent preferentially labeled membrane proteins exposed at the cell surface of erythrocytes as assessed by the degree of radiolabel incorporation into erythrocyte ghost proteins and hemoglobin. Comparison with the lactoperoxidase-[ 125 I]iodide labeling technique revealed that 125 I-sulfo-SHPP labeled cell surface proteins to a much higher specific activity and hemoglobin to a much lower specific activity. Additionally, this reagent was used for selective radiolabeling of membrane proteins on the cytoplasmic face of the plasma membrane by blocking exofacial amino groups with uniodinated sulfo-SHPP, lysing the cells, and then incubating them with 125 I-sulfo-SHPP. Exclusive labeling of either side of the plasma membrane was demonstrated by the labeling of some marker proteins with well-defined spacial orientations on erythroctyes. Transmembrane proteins such as the epidermal growth factor receptor on cultured cells could also be labeled differentially from either side of the plasma membrane

Gamma radiation fields from activity deposited on road and soil surfaces

International Nuclear Information System (INIS)

Hedemann Jensen, P.

1993-12-01

Radioactive material deposited in the environment after an accidental release would cause exposure of the population living in the affected areas. The radiation field will depend on many factors such as radionuclide composition, surface contamination density, removal of activity by weathering and migration, and protective measures like decontamination, ploughing and covering by asphalt. Methods are described for calculation of air kerma rate from deposited activity on road and soil surfaces, both from the initially deposited activity and from activity distributed in the upper layer of soil as well as from activity covered by asphalt or soil. Air kerma rates are calculated for different source geometries and the results are fitted to a power-exponential function of photon energy, depth distributions in soil and horizontal dimensions. Based on this function calculations of air kerma rate can easily be made on a personal computer or programmable pocket calculator for specific radionuclide compositions and different horizontal and vertical distributions of the deposited activity. The calculations are compared to results from other methods like the Monte Carlo method and good agreement is found between the results. (au) (7 tabs., 12 ills., 8 refs.)

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)

Electromyographic activity and 6RM strength in bench press on stable and unstable surfaces.

Science.gov (United States)

Saeterbakken, Atle H; Fimland, Marius S

2013-04-01

The purpose of the study was to compare 6-repetition maximum (6RM) loads and muscle activity in bench press on 3 surfaces, namely, stable bench, balance cushion, and Swiss ball. Sixteen healthy, resistance-trained men (age 22.5 ± 2.0 years, stature 1.82 ± 6.6 m, and body mass 82.0 ± 7.8 kg) volunteered for 3 habituation/strength testing sessions and 1 experimental session. In randomized order on the 3 surfaces, 6RM strength and electromyographic activity of pectoralis major, deltoid anterior, biceps brachii, triceps brachii, rectus abdominis, oblique external and erector spinae were assessed. Relative to stable bench, the 6RM strength was approximately 93% for balance cushion (p ≤ 0.001) and approximately 92% for Swiss ball (p = 0.008); the pectoralis major electromyographic (EMG) activity was approximately 90% using the balance cushion (p = 0.080) and approximately 81% using Swiss ball (p = 0.006); the triceps EMG was approximately 79% using the balance cushion (p = 0.028) and approximately 69% using the Swiss ball (p = 0.002). Relative to balance cushion, the EMG activity in pectoralis, triceps, and erector spinae using Swiss ball was approximately 89% (p = 0.016), approximately 88% (p = 0.014) and approximately 80% (p = 0.020), respectively. In rectus abdominis, the EMG activity relative to Swiss ball was approximately 69% using stable bench (p = 0.042) and approximately 65% using the balance cushion (p = 0.046). Similar EMG activities between stable and unstable surfaces were observed for deltoid anterior, biceps brachii, and oblique external. In conclusion, stable bench press had greater 6RM strength and triceps and pectoralis EMG activity compared with the unstable surfaces. These findings have implications for athletic training and rehabilitation, because they demonstrate an inferior effect of unstable surfaces on muscle activation of prime movers and strength in bench press. If an unstable surface in bench press is desirable, a balance cushion should

Processing method and processing device for liquid waste containing surface active agent and radioactive material

International Nuclear Information System (INIS)

Nishi, Takashi; Matsuda, Masami; Baba, Tsutomu; Yoshikawa, Ryozo; Yukita, Atsushi.

1998-01-01

Washing liquid wastes containing surface active agents and radioactive materials are sent to a deaerating vessel. Ozone is blown into the deaerating vessel. The washing liquid wastes dissolved with ozone are introduced to a UV ray irradiation vessel. UV rays are irradiated to the washing liquid wastes, and hydroxy radicals generated by photodecomposition of dissolved ozone oxidatively decompose surface active agents contained in the washing liquid wastes. The washing liquid wastes discharged from the UV ray irradiation vessel are sent to an activated carbon mixing vessel and mixed with powdery activated carbon. The surface active agents not decomposed in the UV ray irradiation vessel are adsorbed to the activated carbon. Then, the activated carbon and washing liquid wastes are separated by an activated carbon separating/drying device. Radioactive materials (iron oxide and the like) contained in the washing liquid wastes are mostly granular, and they are separated and removed from the washing liquid wastes in the activated carbon separating/drying device. (I.N.)

Identifying the Active Surfaces of Electrochemically Tuned LiCoO2 for Oxygen Evolution Reaction

International Nuclear Information System (INIS)

Lu, Zhiyi; Chen, Guangxu; Li, Yanbin; Wang, Haotian; Xie, Jin

2017-01-01

Identification of active sites for catalytic processes has both fundamental and technological implications for rational design of future catalysts. Herein, we study the active surfaces of layered lithium cobalt oxide (LCO) for the oxygen evolution reaction (OER) using the enhancement effect of electrochemical delithiation (De-LCO). Our theoretical results indicate that the most stable (0001) surface has a very large overpotential for OER independent of lithium content. In contrast, edge sites such as the nonpolar (1120) and polar (0112) surfaces are predicted to be highly active and dependent on (de)lithiation. The effect of lithium extraction from LCO on the surfaces and their OER activities can be understood by the increase of Co 4+ sites relative to Co 3+ and by the shift of active oxygen 2p states. Experimentally, it is demonstrated that LCO nanosheets, which dominantly expose the (0001) surface show negligible OER enhancement upon delithiation. However, a noticeable increase in OER activity (~0.1 V in overpotential shift at 10 mA cm –2 ) is observed for the LCO nanoparticles, where the basal plane is greatly diminished to expose the edge sites, consistent with the theoretical simulations. In addition, we find that the OER activity of De-LCO nanosheets can be improved if we adopt an acid etching method on LCO to create more active edge sites, which in turn provides a strong evidence for the theoretical indication.

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

Covalent organic polymer functionalization of activated carbon surfaces through acyl chloride for environmental clean-up

DEFF Research Database (Denmark)

Mines, Paul D.; Thirion, Damien; Uthuppu, Basil

2017-01-01

Nanoporous networks of covalent organic polymers (COPs) are successfully grafted on the surfaces of activated carbons, through a series of surface modification techniques, including acyl chloride formation by thionyl chloride. Hybrid composites of activated carbon functionalized with COPs exhibit...

Effects of Different Footwear Properties and Surface Instability on Neuromuscular Activity and Kinematics During Jumping.

Science.gov (United States)

Lesinski, Melanie; Prieske, Olaf; Borde, Ron; Beurskens, Rainer; Granacher, Urs

2018-04-13

Lesinski, M, Prieske, O, Borde, R, Beurskens, R, and Granacher, U. Effects of different footwear properties and surface instability on neuromuscular activity and kinematics during jumping. J Strength Cond Res XX(X): 000-000, 2018-The purpose of this study was to examine sex-specific effects of different footwear properties vs. barefoot condition during the performance of drop jumps (DJs) on stable and unstable surfaces on measures of jump performance, electromyographic (EMG) activity, and knee joint kinematics. Drop jump performance, EMG activity of lower-extremity muscles, as well as sagittal and frontal knee joint kinematics were tested in 28 healthy male (n = 14) and female (n = 14) physically active sports science students (23 ± 2 years) during the performance of DJs on stable and unstable surfaces using different footwear properties (elastic vs. minimal shoes) vs. barefoot condition. Analysis revealed a significantly lower jump height and performance index (Δ7-12%; p footwear conditions (Δ29%; p footwear-surface interactions were detected. Our findings revealed that surface instability had an impact on DJ performance, thigh/shank muscle activity, and knee joint kinematics. In addition, the single factors "footwear" and "sex" modulated knee joint kinematics during DJs. However, hardly any significant interaction effects were found. Thus, additional footwear-related effects can be neglected when performing DJs during training on different surfaces.

p-Chlorophenol adsorption on activated carbons with basic surface properties

Science.gov (United States)

Lorenc-Grabowska, Ewa; Gryglewicz, Grażyna; Machnikowski, Jacek

2010-05-01

The adsorption of p-chlorophenol (PCP) from aqueous solution on activated carbons (ACs) with basic surface properties has been studied. The ACs were prepared by two methods. The first method was based on the modification of a commercial CWZ AC by high temperature treatment in an atmosphere of ammonia, nitrogen and hydrogen. The second approach comprised the carbonization followed by activation of N-enriched polymers and coal tar pitch using CO 2 and steam as activation agent. The resultant ACs were characterized in terms of porous structure, elemental composition and surface chemistry (pH PZC, acid/base titration, XPS). The adsorption of PCP was carried out from an aqueous solution in static conditions. Equilibrium adsorption isotherm was of L2 type for polymer-based ACs, whereas L3-type isotherm was observed for CWZ ACs series. The Langmuir monolayer adsorption capacity was related to the porous structure and the amount of basic sites. A good correlation was found between the adsorption capacity and the volume of micropores with a width water molecule adsorption on the PCP uptake is discussed.

Taste-Active Maillard Reaction Products in Roasted Garlic (Allium sativum).

Science.gov (United States)

Wakamatsu, Junichiro; Stark, Timo D; Hofmann, Thomas

2016-07-27

In order to gain first insight into candidate Maillard reaction products formed upon thermal processing of garlic, mixtures of glucose and S-allyl-l-cysteine, the major sulfur-containing amino acid in garlic, were low-moisture heated, and nine major reaction products were isolated. LC-TOF-MS, 1D/2D NMR, and CD spectroscopy led to their identification as acortatarin A (1), pollenopyrroside A (2), epi-acortatarin A (3), xylapyrroside A (4), 5-hydroxymethyl-1-[(5-hydroxymethyl-2-furanyl)methyl]-1H-pyrrole-2-carbalde-hyde (5), 3-(allylthio)-2-(2-formyl-5-hydroxymethyl-1H-pyrrol-1-yl)propanoic acid (6), (4S)-4-(allylthiomethyl)-3,4-dihydro-3-oxo-1H-pyrrolo[2,1-c][1,4]oxazine-6-carbaldehyde (7), (2R)-3-(allylthio)-2-[(4R)-4-(allylthiomethyl)-6-formyl-3-oxo-3,4-dihydropyrrolo-[1,2-a]pyrazin-2(1H)-yl]propanoic acid (8), and (2R)-3-(allylthio)-2-((4S)-4-(allylthiomethyl)-6-formyl-3-oxo-3,4-dihydropyrrolo-[1,2-a]pyrazin-2(1H)-yl)propanoic acid (9). Among the Maillard reaction products identified, compounds 5-9 have not previously been published. The thermal generation of the literature known spiroalkaloids 1-4 is reported for the first time. Sensory analysis revealed a bitter taste with thresholds between 0.5 and 785 μmol/kg for 1-5 and 7-9. Compound 6 did not show any intrinsic taste (water) but exhibited a strong mouthfullness (kokumi) enhancing activity above 186 μmol/kg. LC-MS/MS analysis showed 1-9 to be generated upon pan-frying of garlic with the highest concentration of 793.7 μmol/kg found for 6, thus exceeding its kokumi threshold by a factor of 4 and giving evidence for its potential taste modulation activity in processed garlic preparations.

Influence of porous texture and surface chemistry on the CO₂ adsorption capacity of porous carbons: acidic and basic site interactions.

Science.gov (United States)

Sánchez-Sánchez, Angela; Suárez-García, Fabián; Martínez-Alonso, Amelia; Tascón, Juan M D

2014-12-10

Doped porous carbons exhibiting highly developed porosity and rich surface chemistry have been prepared and subsequently applied to clarify the influence of both factors on carbon dioxide capture. Nanocasting was selected as synthetic route, in which a polyaramide precursor (3-aminobenzoic acid) was thermally polymerized inside the porosity of an SBA-15 template in the presence of different H3PO4 concentrations. The surface chemistry and the porous texture of the carbons could be easily modulated by varying the H3PO4 concentration and carbonization temperature. Porous texture was found to be the determinant factor on carbon dioxide adsorption at 0 °C, while surface chemistry played an important role at higher adsorption temperatures. We proved that nitrogen functionalities acted as basic sites and oxygen and phosphorus groups as acidic ones toward adsorption of CO2 molecules. Among the nitrogen functional groups, pyrrolic groups exhibited the highest influence, while the positive effect of pyridinic and quaternary functionalities was smaller. Finally, some of these N-doped carbons exhibit CO2 heats of adsorption higher than 42 kJ/mol, which make them excellent candidates for CO2 capture.

Novel alternating polymer adsorption/surface activation self-assembled film based on hydrogen bond

Energy Technology Data Exchange (ETDEWEB)

Zhang Yongjun; Yang Shuguang; Guan Ying; Miao Xiaopeng; Cao Weixiao; Xu Jian

2003-08-01

By combining hydrogen bonding layer-by-layer self-assembly and the stepwise chemisorption method, a new alternating polymer adsorption/surface activation self-assembly method was developed. First a layer of diphenylamine-4-diazonium-formaldehyde resin (diazo resin or DR) is deposited on a substrate. In the following surface activation step, the diazonium groups on the surface couple with resorcin in the outside solution. The deposition of another layer of DR is feasible due to the formation of hydrogen bond between the diazonium group of DR and the hydroxy group of the resorcin moieties. The resulting film is photosensitive. After UV irradiation, the film becomes very stable towards polar organic solvents.

Non-covalent functionalisation of C{sub 30} fullerene by pyrrole-n-carboxylic acid (n=2, 3). Density functional theory studies

Energy Technology Data Exchange (ETDEWEB)

Harismah, Kun [Univ. Muhammadiyah Surakarta (Indonesia). Dept. of Chemical Engineering; Mirzaei, Mahmoud [Isfahan Univ. of Medical Sciences (Iran, Islamic Republic of). Bioinformatics Research Center; Ghasemi, Nahid [Islamic Azad Univ., Arak (Iran, Islamic Republic of). Dept. of Chemistry; Nejati, Mohammad [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Dept. of Chemistry

2018-04-01

For functionalisation of a representative C{sub 30} fullerene nanostructure by pyrrole-n-carboxylic acid (PnCA; n=2, 3) their stabilities and properties were investigated based on density functional theory calculations. Parallel calculations were also done for C{sub 60} fullerene as evidence for comparing the results. Non-covalent interactions are considered to make the functionalised structures. In contrast with the spherical shape of C{sub 60}, the shape of C{sub 30} fullerene is elliptical; therefore, the functionalisation processes were done for both axial and equatorial elliptical positions (AC{sub 30} and EC{sub 30}). The results indicated that both the positions of C{sub 30} have almost equivalent chances to be functionalised by PnCA; but functionalisation by P2CA is slightly more favourable than P3CA, either for C{sub 60}. The illustrated molecular orbitals' distributions indicated that the direction of charge transfer could be considered from PnCA counterparts to fullerene counterparts. The molecular properties indicated more reactivity for C{sub 30} than for C{sub 60} fullerene. Finally, the atomic scale quadrupole coupling constants indicated different roles for N and O atoms of PnCA in the functionalised models.

Effect of instruction, surface stability, and load intensity on trunk muscle activity.

Science.gov (United States)

Bressel, Eadric; Willardson, Jeffrey M; Thompson, Brennan; Fontana, Fabio E

2009-12-01

The aim of this study was to assess the effect of verbal instruction, surface stability, and load intensity on trunk muscle activity levels during the free weight squat exercise. Twelve trained males performed a free weight squat under four conditions: (1) standing on stable ground lifting 50% of their 1-repetition maximum (RM), (2) standing on a BOSU balance trainer lifting 50% of their 1-RM, (3) standing on stable ground lifting 75% of their 1-RM, and (4) receiving verbal instructions to activate the trunk muscles followed by lifting 50% of their 1-RM. Surface EMG activity from muscles rectus abdominis (RA), external oblique (EO), transversus abdominis/internal oblique (TA/IO), and erector spinae (ES) were recorded for each condition and normalized for comparisons. Muscles RA, EO, and TA/IO displayed greater peak activity (39-167%) during squats with instructions compared to the other squat conditions (P=0.04-0.007). Peak EMG activity of muscle ES was greater for the 75% 1-RM condition than squats with instructions or lifting 50% of 1-RM (P=0.04-0.02). The results indicate that if the goal is to enhance EMG activity of the abdominal muscles during a multi-joint squat exercise then verbal instructions may be more effective than increasing load intensity or lifting on an unstable surface. However, in light of other research, conscious co-activation of the trunk muscles during the squat exercise may lead to spinal instability and hazardous compression forces in the lumbar spine.

Development of reconstitution method for surveillance specimens using surface activated joining

Energy Technology Data Exchange (ETDEWEB)

Nakamura, Terumi; Kaihara, Shoichiro; Yoshida, Kazuo; Sato, Akira [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan); Onizawa, Kunio; Nishiyama, Yutaka; Fukaya, Kiyoshi; Suzuki, Masahide

1996-03-01

Evaluation of embrittlement of reactor vessel steel due to irradiation requires surveillance tests. However, many surveillance specimens are necessary for nuclear plants life extension. Therefore, a specimen reconstitution technique has become important to provide the many specimens for continued surveillance. A surface activated joining (SAJ) method has been developed to join various materials together at low temperatures with little deformation, and is useful to bond irradiated specimens. To assess the validity of this method, Charpy impact tests were carried out, and the characteristics caused by heating during joining were measured. The test results showed the Charpy impact values were almost the same as base materials, and surface activated joining reduced heat affected zone to less than 2 mm. (author).

Patched bimetallic surfaces are active catalysts for ammonia decomposition.

Science.gov (United States)

Guo, Wei; Vlachos, Dionisios G

2015-10-07

Ammonia decomposition is often used as an archetypical reaction for predicting new catalytic materials and understanding the very reason of why some reactions are sensitive on material's structure. Core-shell or surface-segregated bimetallic nanoparticles expose outstanding activity for many heterogeneously catalysed reactions but the reasons remain elusive owing to the difficulties in experimentally characterizing active sites. Here by performing multiscale simulations in ammonia decomposition on various nickel loadings on platinum (111), we show that the very high activity of core-shell structures requires patches of the guest metal to create and sustain dual active sites: nickel terraces catalyse N-H bond breaking and nickel edge sites drive atomic nitrogen association. The structure sensitivity on these active catalysts depends profoundly on reaction conditions due to kinetically competing relevant elementary reaction steps. We expose a remarkable difference in active sites between transient and steady-state studies and provide insights into optimal material design.

CLINICAL SURFACES - Activity-Based Computing for Distributed Multi-Display Environments in Hospitals

Science.gov (United States)

Bardram, Jakob E.; Bunde-Pedersen, Jonathan; Doryab, Afsaneh; Sørensen, Steffen

A multi-display environment (MDE) is made up of co-located and networked personal and public devices that form an integrated workspace enabling co-located group work. Traditionally, MDEs have, however, mainly been designed to support a single “smart room”, and have had little sense of the tasks and activities that the MDE is being used for. This paper presents a novel approach to support activity-based computing in distributed MDEs, where displays are physically distributed across a large building. CLINICAL SURFACES was designed for clinical work in hospitals, and enables context-sensitive retrieval and browsing of patient data on public displays. We present the design and implementation of CLINICAL SURFACES, and report from an evaluation of the system at a large hospital. The evaluation shows that using distributed public displays to support activity-based computing inside a hospital is very useful for clinical work, and that the apparent contradiction between maintaining privacy of medical data in a public display environment can be mitigated by the use of CLINICAL SURFACES.

Precursor type affecting surface properties and catalytic activity of sulfated zirconia

Directory of Open Access Journals (Sweden)

Zarubica Aleksandra R.

2007-01-01

Full Text Available Zirconium-hydroxide precursor samples are synthesized from Zr-hydroxide, Zr-nitrate, and Zr-alkoxide, by precipitation/impregnation, as well as by a modified sol-gel method. Precursor samples are further sulphated for the intended SO4 2- content of 4 wt.%, and calcined at 500-700oC. Differences in precursors’ origin and calcination temperature induce the incorporation of SO4 2- groups into ZrO2 matrices by various mechanisms. As a result, different amounts of residual sulphates are coupled with other structural, as well as surface properties, resulting in various catalytic activities of sulphated zirconia samples. Catalyst activity and selectivity are a complex synergistic function of tetragonal phase fraction, sulphates contents, textural and surface characteristics. Superior activity of SZ of alkoxide origin can be explained by a beneficial effect of meso-pores owing to a better accommodation of coke deposits.

Crystal structure of the catalytic domain of PigE: a transaminase involved in the biosynthesis of 2-methyl-3-n-amyl-pyrrole (MAP) from Serratia sp. FS14.

Science.gov (United States)

Lou, Xiangdi; Ran, Tingting; Han, Ning; Gao, Yanyan; He, Jianhua; Tang, Lin; Xu, Dongqing; Wang, Weiwu

2014-04-25

Prodigiosin, a tripyrrole red pigment synthesized by Serratia and some other microbes through a bifurcated biosynthesis pathway, MBC (4-methoxy-2,2'-bipyrrole-5-carbaldehyde) and MAP (2-methyl-3-n-amyl-pyrrole) are synthesized separately and then condensed by PigC to form prodigiosin. MAP is synthesized sequentially by PigD, PigE and PigB. PigE catalyzes the transamination of an amino group to the aldehyde group of 3-acetyloctanal, resulting in an aminoketone, which spontaneously cyclizes to form H2MAP. Here we report the crystal structure of the catalytic domain of PigE which involved in the biosynthesis of prodigiosin precursor MAP for the first time to a resolution of 2.3Å with a homodimer in the asymmetric unit. The monomer of PigE catalytic domain is composed of three domains with PLP as cofactor: a small N-terminal domain connecting the catalytic domain with the front part of PigE, a large PLP-binding domain and a C-terminal domain. The residues from both monomers build the PLP binding site at the interface of the dimer which resembles the other PLP-dependent enzymes. Structural comparison of PigE with Thermus thermophilus AcOAT showed a higher hydrophobic and smaller active site of PigE, these differences may be the reason for substrate specificity. Copyright © 2014 Elsevier Inc. All rights reserved.

The effects of surface condition on abdominal muscle activity during single-legged hold exercise.

Science.gov (United States)

Ha, Sung-min; Oh, Jae-seop; Jeon, In-cheol; Kwon, Oh-yun

2015-02-01

To treat low-back pain, various spinal stability exercises are commonly used to improve trunk muscle function and strength. Because human movement for normal daily activity occurs in multi-dimensions, the importance of exercise in multi-dimensions or on unstable surfaces has been emphasized. Recently, a motorized rotating platform (MRP) for facilitating multi-dimensions dynamic movement was introduced for clinical use. However, the abdominal muscle activity with this device has not been reported. The purpose of this study was to compare the abdominal muscle activity (rectus abdominis, external and internal oblique muscles) during an active single-leg-hold (SLH) exercise on a floor (stable surface), foam roll, and motorized rotating platform (MRP). Thirteen healthy male subjects participated in this study. Using electromyography, the abdominal muscle activity was measured while the subjects performed SLH exercises on floor (stable surface), foam roll, and MRP. There were significant differences in the abdominal muscle activities among conditions (P.05) (Fig. 2). After the Bonferroni correction, however, no significant differences among conditions remained, except for differences in both side IO muscle activity between the floor and foam roll conditions (padjexercises on a foam roll and MRP is more effective increased activities of both side of RA and IO, and Rt. EO compared to floor condition. However, there were no significant differences in abdominal muscles activity in the multiple comparison between conditions (mean difference were smaller than the standard deviation in the abdominal muscle activities) (padj>0.017), except for differences in both side IO muscle activity between the floor (stable surface) and foam roll (padj<0.017) (effect size: 0.79/0.62 (non-supporting/supporting leg) for foam-roll versus floor). Copyright © 2014 Elsevier Ltd. All rights reserved.

Enhanced oxygen reduction activity on surface-decorated perovskite thin films for solid oxide fuel cells

KAUST Repository

Mutoro, Eva; Crumlin, Ethan J.; Biegalski, Michael D.; Christen, Hans M.; Shao-Horn, Yang

2011-01-01

Surface-decoration of perovskites can strongly affect the oxygen reduction activity, and therefore is a new and promising approach to improve SOFC cathode materials. In this study, we demonstrate that a small amount of secondary phase on a (001) La 0.8Sr 0.2CoO 3-δ (LSC) surface can either significantly activate or passivate the electrode. LSC (001) microelectrodes prepared by pulsed laser deposition on a (001)-oriented yttria-stabilized zirconia (YSZ) substrate were decorated with La-, Co-, and Sr-(hydr)oxides/carbonates. "Sr"-decoration with nanoparticle coverage in the range from 50% to 80% of the LSC surface enhanced the surface exchange coefficient, k q, by an order of magnitude while "La"- decoration and "Co"-decoration led to no change and reduction in k q, respectively. Although the physical origin for the enhancement is not fully understood, results from atomic force microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy suggest that the observed k q enhancement for "Sr"-decorated surfaces can be attributed largely to catalytically active interface regions between surface Sr-enriched particles and the LSC surface. © 2011 The Royal Society of Chemistry.

Bio-active molecules modified surfaces enhanced mesenchymal stem cell adhesion and proliferation

International Nuclear Information System (INIS)

Mobasseri, Rezvan; Tian, Lingling; Soleimani, Masoud; Ramakrishna, Seeram; Naderi-Manesh, Hossein

2017-01-01

Surface modification of the substrate as a component of in vitro cell culture and tissue engineering, using bio-active molecules including extracellular matrix (ECM) proteins or peptides derived ECM proteins can modulate the surface properties and thereby induce the desired signaling pathways in cells. The aim of this study was to evaluate the behavior of human bone marrow mesenchymal stem cells (hBM-MSCs) on glass substrates modified with fibronectin (Fn), collagen (Coll), RGD peptides (RGD) and designed peptide (R-pept) as bio-active molecules. The glass coverslips were coated with fibronectin, collagen, RGD peptide and R-peptide. Bone marrow mesenchymal stem cells were cultured on different substrates and the adhesion behavior in early incubation times was investigated using scanning electron microscopy (SEM) and confocal microscopy. The MTT assay was performed to evaluate the effect of different bio-active molecules on MSCs proliferation rate during 24 and 72 h. Formation of filopodia and focal adhesion (FA) complexes, two steps of cell adhesion process, were observed in MSCs cultured on bio-active molecules modified coverslips, specifically in Fn coated and R-pept coated groups. SEM image showed well adhesion pattern for MSCs cultured on Fn and R-pept after 2 h incubation, while the shape of cells cultured on Coll and RGD substrates indicated that they might experience stress condition in early hours of culture. Investigation of adhesion behavior, as well as proliferation pattern, suggests R-peptide as a promising bio-active molecule to be used for surface modification of substrate in supporting and inducing cell adhesion and proliferation. - Highlights: • Bioactive molecules modified surface is a strategy to design biomimicry scaffold. • Bi-functional Tat-derived peptide (R-pept) enhanced MSCs adhesion and proliferation. • R-pept showed similar influences to fibronectin on FA formation and attachment.

(3′R-3′-Benzyl-2′,3′-dihydro-1H-spiro[indole-3,1′-naphtho[2,3-c]pyrrole]-2,4′,9′-trione

Directory of Open Access Journals (Sweden)

Garima Sharma

2012-09-01

Full Text Available In the title compound, C26H18N2O3, the maximum deviations from planarity for the tetrahydro-1H-naphtho[2,3-c]pyrrole and indoline rings systems are 0.091 (1 and 0.012 (2 Å, respectively. These ring systems make a dihedral angle of 89.95 (6° with each other and they make dihedral angles of 73.42 (8 and 71.28 (9°, respectively, with the benzene ring. In the crystal, inversion dimers linked by pairs of N—H...O hydrogen bonds generate R22(8 loops and C—H...O interactions connect the dimers into corrugated sheets lying parallel to the bc plane.

Effect of chemisorbed surface species on the photocatalytic activity of TiO2 nanoparticulate films

International Nuclear Information System (INIS)

Cao Yaan; Yang Wensheng; Chen Yongmei; Du Hui; Yue, Polock

2004-01-01

TiO 2 sols prepared in acidic and basic medium were deposited into films by a spin coating method. Photodegradation experiments showed that photocatalytic activity of the films prepared from acidic sol was much higher than that from basic sol. It is identified that there are more chemisorbed species of CO 2 on the surface of the TiO 2 films from the basic sol than on the surface of the TiO 2 films from the acidic sol. The chemisorbed species of CO 2 reduce the concentration of active species such as hydroxyl group and bridging oxygen on surface of the TiO 2 film and contribute to the formation of surface electron traps in the band gap which are detrimental to charge separation, thus lowering the photocatalytic activity

FRACTAL ANALYSIS OF PHYSICAL ADSORPTION ON SURFACES OF ACID ACTIVATED BENTONITES FROM SERBIA

Directory of Open Access Journals (Sweden)

Ljiljana Rožić

2008-11-01

Full Text Available Solid surfaces are neither ideally regular, that is, morphological and energeticcally homogeneous, nor are they fully irregular or fractal. Instead, real solid surfaces exhibit a limited degree of organization quantified by the fractal dimension, D. Fractal analysis was applied to investigate the effect of concentrations of HCl solutions on the structural and textural properties of chemically activated bentonite from southern Serbia. Acid treatment of bentonites is applied in order to remove impurities and various exchangeable cations from bentonite clay. Important physical changes in acid-activated smectite are the increase of the specific surface area and of the average pore volume, depending on acid strength, time and temperature of a treatment. On the basis of the sorption-structure analysis, the fractal dimension of the bentonite surfaces was determined by Mahnke and Mögel method. The fractal dimension evaluated by this method was 2.11 for the AB3 and 1.94 for the AB4.5 sample. The estimation of the values of the fractal dimension of activated bentonites was performed in the region of small pores, 0.5 nm < rp < 2 nm.

The effects of work surface hardness on mechanical stress, muscle activity, and wrist postures.

Science.gov (United States)

Kim, Jeong Ho; Aulck, Lovenoor; Trippany, David; Johnson, Peter W

2015-01-01

Contact pressure is a risk factor which can contribute to musculoskeletal disorders. The objective of the present study was to determine whether a work surface with a soft, pliable front edge could reduce contact pressure, muscle activity, and subjective musculoskeletal comfort, and improve wrist posture relative to a conventional, hard work surface. In a repeated-measures blinded experiment with eighteen subjects (8 females and 10 males), contact pressure, wrist posture, typing productivity, perceived fatigue, wrist and shoulder muscle activity, and subjective comfort were compared between the two different work surfaces during keyboard use, mouse use and mixed mouse and keyboard use. The results showed that across the three modes of computer work, the contact pressure was lower on the soft-edge work surface compared to the conventional work surface (p's work surfaces. Given the significant reduction in contact pressure and corresponding lower ratings in perceived fatigue, the soft-edge work surface subjectively and objectively improved measures of contact stress which may reduce physical exposures associated with the onset and development of musculoskeletal disorders.

Protein immobilization on epoxy-activated thin polymer films: effect of surface wettability and enzyme loading.

Science.gov (United States)

Chen, Bo; Pernodet, Nadine; Rafailovich, Miriam H; Bakhtina, Asya; Gross, Richard A

2008-12-02

A series of epoxy-activated polymer films composed of poly(glycidyl methacrylate/butyl methacrylate/hydroxyethyl methacrylate) were prepared. Variation in comonomer composition allowed exploration of relationships between surface wettability and Candida antartica lipase B (CALB) binding to surfaces. By changing solvents and polymer concentrations, suitable conditions were developed for preparation by spin-coating of uniform thin films. Film roughness determined by AFM after incubation in PBS buffer for 2 days was less than 1 nm. The occurrence of single CALB molecules and CALB aggregates at surfaces was determined by AFM imaging and measurements of volume. Absolute numbers of protein monomers and multimers at surfaces were used to determine values of CALB specific activity. Increased film wettability, as the water contact angle of films increased from 420 to 550, resulted in a decreased total number of immobilized CALB molecules. With further increases in the water contact angle of films from 55 degrees to 63 degrees, there was an increased tendency of CALB molecules to form aggregates on surfaces. On all flat surfaces, two height populations, differing by more than 30%, were observed from height distribution curves. They are attributed to changes in protein conformation and/or orientation caused by protein-surface and protein-protein interactions. The fraction of molecules in these populations changed as a function of film water contact angle. The enzyme activity of immobilized films was determined by measuring CALB-catalyzed hydrolysis of p-nitrophenyl butyrate. Total enzyme specific activity decreased by decreasing film hydrophobicity.

Novel Chiroptical Analysis of Hemoglobin by Surface Enhanced Resonance Raman Optical Activity Spectroscopy

DEFF Research Database (Denmark)

Brazhe, Nadezda; Brazhe, Alexey; Sosnovtseva, Olga

2010-01-01

The metalloprotein hemoglobin (Hb) was studied using surface enhanced resonance Raman spectroscopy (SERRS) and surface enhanced resonance Raman optical activity (SERROA). The SERROA results are analyzed and compared with the SERRS, and the later to the resonance Raman (RRS) performed on Hb...

Metallopolymer capacitor in "one pot" by self-directed UV-assisted process.

Science.gov (United States)

Ijeri, Vijaykumar S; Nair, Jijeesh R; Gerbaldi, Claudio; Bongiovanni, Roberta M; Penazzi, Nerino

2010-11-01

Silver metalized methacrylate films are prepared by single-step UV curing process with good conductivity on both sides. The major component of the composite is Bisphenol A ethoxylate dimethacrylate, which can be photopolymerized by a photoreactive initiator under UV light. Under the same conditions of UV irradiation, silver ions are deposited as metal nanoparticles while the pyrrole is oxidized to polypyrrole. The migration of silver ions and pyrrole toward both surfaces during polymerization leads to the formation of a metallo-polymer capacitor. The composite films are characterized by SEM-EDX and electrical measurements for possible applications as capacitors in flexible and/or nonplanar electronics.

Role of nanostructured gold surfaces on monocyte activation and Staphylococcus epidermidis biofilm formation

Directory of Open Access Journals (Sweden)

Svensson S

2014-02-01

Full Text Available Sara Svensson,1,2 Magnus Forsberg,1,2 Mats Hulander,1,2 Forugh Vazirisani,1,2 Anders Palmquist,1,2 Jukka Lausmaa,2,3 Peter Thomsen,1,2 Margarita Trobos1,21Department of Biomaterials, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden; 2BIOMATCELL VINN Excellence Center of Biomaterials and Cell Therapy, Gothenburg, Sweden; 3SP Technical Research Institute of Sweden, Borås, SwedenAbstract: The role of material surface properties in the direct interaction with bacteria and the indirect route via host defense cells is not fully understood. Recently, it was suggested that nanostructured implant surfaces possess antimicrobial properties. In the current study, the adhesion and biofilm formation of Staphylococcus epidermidis and human monocyte adhesion and activation were studied separately and in coculture in different in vitro models using smooth gold and well-defined nanostructured gold surfaces. Two polystyrene surfaces were used as controls in the monocyte experiments. Fluorescent viability staining demonstrated a reduction in the viability of S. epidermidis close to the nanostructured gold surface, whereas the smooth gold correlated with more live biofilm. The results were supported by scanning electron microscopy observations, showing higher biofilm tower formations and more mature biofilms on smooth gold compared with nanostructured gold. Unstimulated monocytes on the different substrates demonstrated low activation, reduced gene expression of pro- and anti-inflammatory cytokines, and low cytokine secretion. In contrast, stimulation with opsonized zymosan or opsonized live S. epidermidis for 1 hour significantly increased the production of reactive oxygen species, the gene expression of tumor necrosis factor-α (TNF-α, interleukin-1β (IL-1β, IL-6, and IL-10, as well as the secretion of TNF-α, demonstrating the ability of the cells to elicit a response and actively phagocytose prey. In addition, cells cultured on the smooth

Preparation of self-cleaning surfaces with a dual functionality of superhydrophobicity and photocatalytic activity

Science.gov (United States)

Park, Eun Ji; Yoon, Hye Soo; Kim, Dae Han; Kim, Yong Ho; Kim, Young Dok

2014-11-01

Thin film of polydimethylsiloxane (PDMS) was deposited on SiO2 nanoparticles by chemical vapor deposition, and SiO2 became completely hydrophobic after PDMS coating. Mixtures of TiO2 and PDMS-coated SiO2 nanoparticles with various relative ratios were prepared, and distributed on glass surfaces, and water contact angles and photocatalytic activities of these surfaces were studied. Samples consisting of TiO2 and PDMS-coated SiO2 with a ratio of 7:3 showed a highly stable superhydrophobicity under UV irradiation with a water contact angle of 165° and UV-driven photocatalytic activity for decomposition of methylene blue and phenol in aqueous solution. Our process can be exploited for fabricating self-cleaning surfaces with dual functionality of superhydrophobicity and photocatalytic activity at the same time.

Effect of sulfation on the surface activity of CaO for N{sub 2}O decomposition

Energy Technology Data Exchange (ETDEWEB)

Wu, Lingnan, E-mail: wulingnan@126.com [School of Energy, Power and Mechanical Engineering, North China Electric Power University, 102206 Beijing (China); National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, 102206 Beijing (China); Hu, Xiaoying, E-mail: huxy@ncepu.edu.cn [National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, 102206 Beijing (China); Qin, Wu, E-mail: qinwugx@126.com [National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, 102206 Beijing (China); Dong, Changqing, E-mail: cqdong1@163.com [National Engineering Laboratory for Biomass Power Generation Equipment, North China Electric Power University, 102206 Beijing (China); Yang, Yongping, E-mail: yypncepu@163.com [School of Energy, Power and Mechanical Engineering, North China Electric Power University, 102206 Beijing (China)

2015-12-01

Graphical abstract: - Highlights: • Sulfation of CaO (1 0 0) surface greatly deactivates its surface activity for N{sub 2}O decomposition. • An increase of sulfation degree leads to a decrease of CaO surface activity for N{sub 2}O decomposition. • Sulfation from CaSO{sub 3} into CaSO{sub 4} is the crucial step for deactivating the surface activity for N{sub 2}O decomposition. • The electronic interaction CaO (1 0 0)/CaSO{sub 4} (0 0 1) interface is limited to the bottom layer of CaSO{sub 4} (0 0 1) and the top layer of CaO (1 0 0). • CaSO{sub 4} (0 0 1) and (0 1 0) surfaces show negligible catalytic ability for N{sub 2}O decomposition. - Abstract: Limestone addition to circulating fluidized bed boilers for sulfur removal affects nitrous oxide (N{sub 2}O) emission at the same time, but mechanism of how sulfation process influences the surface activity of CaO for N{sub 2}O decomposition remains unclear. In this paper, we investigated the effect of sulfation on the surface properties and catalytic activity of CaO for N{sub 2}O decomposition using density functional theory calculations. Sulfation of CaO (1 0 0) surface by the adsorption of a single gaseous SO{sub 2} or SO{sub 3} molecule forms stable local CaSO{sub 3} or CaSO{sub 4} on the CaO (1 0 0) surface with strong hybridization between the S atom of SO{sub x} and the surface O anion. The formed local CaSO{sub 3} increases the barrier energy of N{sub 2}O decomposition from 0.989 eV (on the CaO (1 0 0) surface) to 1.340 eV, and further sulfation into local CaSO{sub 4} remarkably increases the barrier energy to 2.967 eV. Sulfation from CaSO{sub 3} into CaSO{sub 4} is therefore the crucial step for deactivating the surface activity for N{sub 2}O decomposition. Completely sulfated CaSO{sub 4} (0 0 1) and (0 1 0) surfaces further validate the negligible catalytic ability of CaSO{sub 4} for N{sub 2}O decomposition.

Laboratory Activity Worksheet to Train High Order Thinking Skill of Student on Surface Chemistry Lecture

Science.gov (United States)

Yonata, B.; Nasrudin, H.

2018-01-01

A worksheet has to be a set with activity which is help students to arrange their own experiments. For this reason, this research is focused on how to train students’ higher order thinking skills in laboratory activity by developing laboratory activity worksheet on surface chemistry lecture. To ensure that the laboratory activity worksheet already contains aspects of the higher order thinking skill, it requires theoretical and empirical validation. From the data analysis results, it shows that the developed worksheet worth to use. The worksheet is worthy of theoretical and empirical feasibility. This conclusion is based on the findings: 1) Assessment from the validators about the theoretical feasibility aspects in the category is very feasible with an assessment range of 95.24% to 97.92%. 2) students’ higher thinking skill from N Gain values ranges from 0.50 (enough) to 1.00 (high) so it can be concluded that the laboratory activity worksheet on surface chemistry lecture is empirical in terms of worth. The empirical feasibility is supported by the responses of the students in very reasonable categories. It is expected that the laboratory activity worksheet on surface chemistry lecture can train students’ high order thinking skills for students who program surface chemistry lecture.

Experimental and Numerical Investigation of Design Parameters for Hydronic Embedded Thermally Active Surfaces

DEFF Research Database (Denmark)

Marcos-Meson, Victor; Pomianowski, Michal Zbigniew; E. Poulsen, Søren

2015-01-01

This paper evaluates the principal design parameters affecting the thermal performance of embedded hydronic Thermally Active Surfaces (TAS), combining the Response Surface Method (RSM) with the Finite Elements Method (FEM). The study ranks the combined effects of the parameters on the heat flux i...

Synthesis and evaluation of some surface active agents from long chain fatty amine

Directory of Open Access Journals (Sweden)

Eissa, A. M. F.

2007-12-01

Full Text Available This study continues our series of synthesis of surface active agents containing heterocyclic moiety. NHeptadecanoyl- 3-(4-oxo-4H-benzo[d][1,3]oxazin-2-yl- acrylamide (4 was used as a new starting material to synthesize propenoxylated nonionic surface active agents having heterocycles such as (thiazole, triazole, benzoxazine, quinazoline, triazine, and oxazine. The structures of the prepared compounds were elucidated by using spectroscopic tools (IR, 1H NMR and Mass spectroscopy. Physical properties such as surface and interfacial tension, cloud point, foaming height, wetting time, emulsification power and critical micelle concentration (CMC were determined. Antimicrobial and biodegradability properties were also screened. It was found that the produced novel groups of nonionic surface active agents have pronounced surface properties and good antimicrobial activities.Este estudio continua nuestra serie sobre la síntesis de agentes surfactantes que contienen grupos heterociclicos. N-Heptadecanoyl-3-(4-oxo-4H-benzo[d][1,3]oxazin-2-yl- acrylamida (4 se usa como nueva materia prima para sintetizar surfactantes noiónico propenoxilado conteniendo herociclos tales como thiazol, triazol, benzoxazina, quinazolina, triazina, y oxazina. Las estructuras de los compuestos preparados se dilucidan mediante herramientas espectroscópicas (IR, 1H NMR and espectroscopía de masas. Se determinan sus propiedades físicas, tensión superficial e interfacial, punto de nube, altura de espuma, poder de emulsificación y concentración micelar critica.También se revisan sus propiedades antimicrobianas y de biodegradabilidad Se encontró que los nuevos compuestos poseían destacadas propiedades superficiales y unas buenas actividades antimicrobianas.

Enhanced visible light-induced photocatalytic activity of surface-modified BiOBr with Pd nanoparticles

Science.gov (United States)

Meng, Xiangchao; Li, Zizhen; Chen, Jie; Xie, Hongwei; Zhang, Zisheng

2018-03-01

Palladium nanoparticles well-dispersed on BiOBr surfaces were successfully prepared via a two-step process, namely hydrothermal synthesis of BiOBr followed by photodeposition of palladium. Surface-exposed palladium nanoparticles may improve the harvesting capacity of visible light photons via the surface plasmonic resonance effect to produce extra electrons. Palladium is an excellent electron acceptor, and therefore favours the separation of photogenerated electron/hole pairs. As a result, palladium significantly improves the photocatalytic activity of BiOBr in the removal of organic pollutants (phenol) under visible light irradiation. In addition to as-prepared samples which were comprehensively characterized, the mechanism for the enhancement via the deposition of palladium nanoparticles was also proposed based on results. This work may serve as solid evidence to confirm that surface-deposited palladium nanoparticles are capable of improving photocatalytic activity, and that photodeposition may be an effective approach to load metal nanoparticles onto a surface.

The hepatitis B virus large surface protein (LHBs) is a transcriptional activator.

Science.gov (United States)

Hildt, E; Saher, G; Bruss, V; Hofschneider, P H

1996-11-01

It has been shown that a C-terminally truncated form of the middle-sized hepatitis B virus (HBV) surface protein (MHBst) functions as a transcriptional activator. This function is dependent on the cytosolic orientation of the N-terminal PreS2 domain of MHBst, but in the case of wild-type MHBs, the PreS2 domain is contranslationally translocated into the ER lumen. Recent reports demonstrated that the PreS2 domain of the large HBV surface protein (LHBs) initially remains on the cytosolic side of the ER membrane after translation. Therefore, the question arose as to whether the LHBs protein exhibits the same transcriptional activator function as MHBst. We show that LHBs, like MHBst, is indeed able to activate a variety of promoter elements. There is evidence for a PKC-dependent activation of AP-1 and NF-kappa B by LHBs. Downstream of the PKC the functionality of c-Raf-1 kinase is a prerequisite for LHBs-dependent activation of AP-1 and NF-kappa B since inhibition of c-Raf-1 kinase abolishes LHBs-dependent transcriptional activation of AP-1 and NF-kappa B.

Influence of nitrogen surface functionalities on the catalytic activity of activated carbon in low temperature SCR of NO{sub x} with NH{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Szymanski, Grzegorz S. [Faculty of Chemistry, Nicolaus Copernicus University, Gagarina 7, 87-100 Torun (Poland); Grzybek, Teresa [Faculty of Fuels and Energy, AGH, University of Science and Technology, Al. Mickiewicza 30, 30-059 Krakow (Poland); Papp, Helmut [Faculty of Chemistry and Mineralogy, Institute of Technical Chemistry, University of Leipzig, Linnerstrasse 3, 04103 Leipzig (Germany)

2004-06-15

The reduction of nitrogen oxide with ammonia was studied using carbon catalysts with chemically modified surfaces. Carbon samples with different surface chemistry were obtained from commercial activated carbon D43/1 (CarboTech, Essen, Germany) by chemical modification involving oxidation with conc. nitric acid (DOx) (1); high temperature treatment (=1000K) under vacuum (DHT) (2); or in ammonia (DHTN, DOxN) (3). Additionally, a portion of the DOx sample was promoted with iron(III) ions (DOxFe). The catalytic tests were performed in a microreactor at a temperature range of 413-573K. The carbon sample annealed under vacuum (DHT) showed the lowest activity. The formation of surface acidic surface oxides by nitric acid treatment (DOx) enhanced the catalytic activity only slightly. However, as can be expected, subsequent promotion of the DOx sample with iron(III) ions increased drastically its catalytic activity. However, this was accompanied by some loss of selectivity, i.e. formation of N{sub 2}O as side product. This effect can be avoided using ammonia-treated carbons which demonstrated reasonable activity with simultaneous high selectivity. The most active and selective among them was the sample that was first oxidized with nitric acid and then heated in an ammonia stream (DOxN). A correlation between catalytic activity and surface nitrogen content was observed. Surface nitrogen species seem to play an important role in catalytic selective reduction of nitrogen oxide with ammonia, possibly facilitating NO{sub 2} formation (a reaction intermediate) as a result of easier chemisorption of oxygen and nitrogen oxide.

Gyroid nanoporous scaffold for conductive polymers

DEFF Research Database (Denmark)

Guo, Fengxiao; Schulte, Lars; Zhang, Weimin

2011-01-01

Conductive nanoporous polymers with interconnected large surface area have been prepared by depositing polypyrrole onto nanocavity walls of nanoporous 1,2-polybutadiene films with gyroid morphology. Vapor phase polymerization of pyrrole was used to generate ultrathin films and prevent pore blocking...

Self-activated, self-limiting reactions on Si surfaces

DEFF Research Database (Denmark)

Morgen, Per; Hvam, Jeanette; Bahari, Ali

The direct thermally activated reactions of oxygen and ammonia with Si surfaces in furnaces have been used for a very long time in the semiconductor industry for the growth of thick oxides and nitride layers respectively. The oxidation mechanism was described in the Deal-Grove model as a diffusion...... mechanism for the direct growth of ultrathin films (0-3 nm) of oxides and nitrides under ultrahigh vacuum conditions. Neutral oxygen and a microwave excited nitrogen plasma interact directly with Si surfaces kept at different temperatures during the reaction. The gas pressures are around 10-6 Torr...... energy of an oxide system, which happened for an ordered structure, at a thickness of 0.7-0.8 nm. Thus this thin oxide structure has definite crystalline features. We have closely monitored the reaction kinetics with normal x-ray induced photoelectron spectroscopies, and also the structure, composition...

Design parameters for measurements of local catalytic activity on surfaces

DEFF Research Database (Denmark)

Johansson, Martin; Johannessen, Tue; Jørgensen, Jan Hoffmann

2006-01-01

Computational fluid dynamics in combination with experiments is used to characterize a gas sampling device for measurements of the local catalytic activity on surfaces. The device basically consists of a quartz capillary mounted concentrically inside an aluminum tube. Reactant gas is blown toward......, the limits of the range in reaction rate, which can be Studied are estimated. (c) 2005 Elsevier B.V. All rights reserved.......Computational fluid dynamics in combination with experiments is used to characterize a gas sampling device for measurements of the local catalytic activity on surfaces. The device basically consists of a quartz capillary mounted concentrically inside an aluminum tube. Reactant gas is blown toward...... limit for the lateral resolution of the measurement, and that a flow rate of the order of 240 (ml/min)(n) is sufficient to achieve this resolution. The sensitivity is reasonable also with high flow rates, due to the presence of a pocket of stagnant gas under the tip of the capillary. Furthermore...

Motor unit recruitment and bursts of activity in the surface electromyogram during a sustained contraction.

Science.gov (United States)

Riley, Zachary A; Terry, Mary E; Mendez-Villanueva, Alberto; Litsey, Jane C; Enoka, Roger M

2008-06-01

Bursts of activity in the surface electromyogram (EMG) during a sustained contraction have been interpreted as corresponding to the transient recruitment of motor units, but this association has never been confirmed. The current study compared the timing of trains of action potentials discharged by single motor units during a sustained contraction with the bursts of activity detected in the surface EMG signal. The 20 motor units from 6 subjects [recruitment threshold, 35.3 +/- 11.3% maximal voluntary contraction (MVC) force] that were detected with fine wire electrodes discharged 2-9 trains of action potentials (7.2 +/- 5.6 s in duration) when recruited during a contraction that was sustained at a force below its recruitment threshold (target force, 25.4 +/- 10.6% MVC force). High-pass filtering the bipolar surface EMG signal improved its correlation with the single motor unit signal. An algorithm applied to the surface EMG was able to detect 75% of the trains of motor unit action potentials. The results indicate that bursts of activity in the surface EMG during a constant-force contraction correspond to the transient recruitment of higher-threshold motor units in healthy individuals, and these results could assist in the diagnosis and design of treatment in individuals who demonstrate deficits in motor unit activation.

Distillation of tar and tar fractions in the presence of surface-active coke

Energy Technology Data Exchange (ETDEWEB)

Jaeppelt, A; Klaus, J

1943-01-01

The tar obtained by low-temperature carbonization of Upper Silesian gas coke and fractions from this tar were distilled in the presence of different grades of coke dust with varying surface activity; the coke had been activated by steam in the course of its production by low-temperature carbonization. The surface activity of the coke dusts was measured by determining the heat of wetting with C/sub 6/H/sub 6/. Tar and coke dust, both anhydrous, were mixed in a kneading machine in such proportions that the capillaries of the dust were saturated and enough ''externally'' bound tar was present to permit briquetting. The briquets were distilled without cracking and with steam as heating medium. The yield and quality of the distillate depended on the magnitude of the internal surface of the coke dust used; a mixture of a very active coke from brown coal and tar yielded a distillate with Conradson carbon residue of 1.34 percent, asphalt content 6.1 percent and eta/sub 20/ 5.4/sup 0/ E. as compared with C residue of 10.95 percent, asphalt content 33.5 percent and eta/sub 20/ 123.6/sup 0/ E. of the distillate obtained in the absence of surface-active coke. Even higher-boiling fractions can be improved by this treatment, although it is preferable to use oils with an initial boiling point below 300/sup 0/. The ratio of oil to adsorbent is not critical, but better results were obtained with higher percentages of added coke dust. The process in its present form is not suited for the conversion of crude creosote to useful phenols.

Effect of plasma-induced surface charging on catalytic processes: application to CO2 activation

Science.gov (United States)

Bal, Kristof M.; Huygh, Stijn; Bogaerts, Annemie; Neyts, Erik C.

2018-02-01

Understanding the nature and effect of the multitude of plasma-surface interactions in plasma catalysis is a crucial requirement for further process development and improvement. A particularly intriguing and rather unique property of a plasma-catalytic setup is the ability of the plasma to modify the electronic structure, and hence chemical properties, of the catalyst through charging, i.e. the absorption of excess electrons. In this work, we develop a quantum chemical model based on density functional theory to study excess negative surface charges in a heterogeneous catalyst exposed to a plasma. This method is specifically applied to investigate plasma-catalytic CO2 activation on supported M/Al2O3 (M = Ti, Ni, Cu) single atom catalysts. We find that (1) the presence of a negative surface charge dramatically improves the reductive power of the catalyst, strongly promoting the splitting of CO2 to CO and oxygen, and (2) the relative activity of the investigated transition metals is also changed upon charging, suggesting that controlled surface charging is a powerful additional parameter to tune catalyst activity and selectivity. These results strongly point to plasma-induced surface charging of the catalyst as an important factor contributing to the plasma-catalyst synergistic effects frequently reported for plasma catalysis.

Use of polyamfolit complexes of ethyl-amino-crotonate/acrylic acid with surface-active materials for radionuclide extraction

International Nuclear Information System (INIS)

Kabdyrakova, A.M.; Artem'ev, O.I.; Protskij, A.V.; Bimendina, L.A.; Yashkarova, M.G.; Orazzhanova, L.K.

2005-01-01

Pentifylline of betaine structure was synthesised on the basis of 3-aminocrotonate and acrylic acid. Polyamfolit composition and its complexes with anionic surface-active material (lauryl sulfate of sodium) were determined. It is revealed that complex formation occurs with [polyamfolit]:[surface active material]=1:1 ratio and is accompanied by significant reduce of system characteristics viscosity. The paper presents results of [polyamfolit]:[surface active material] complex apply experimental investigation for radionuclide directed migration in soil. (author)

Surface modification and electrochemical properties of activated carbons for supercapacitor electrodes

Science.gov (United States)

Yang, Dan; Qiu, Wenmei; Xu, Jingcai; Han, Yanbing; Jin, Hongxiao; Jin, Dingfeng; Peng, Xiaoling; Hong, Bo; Li, Ji; Ge, Hongliang; Wang, Xinqing

2015-12-01

Modifications with different acids (HNO3, H2SO4, HCl and HF, respectively) were introduced to treat the activated carbons (ACs) surface. The microstructures and surface chemical properties were discussed by X-ray diffraction (XRD), thermogravimetric analysis (TGA), ASAP, Raman spectra and Fourier transform infrared (FTIR) spectra. The ACs electrode-based supercapacitors were assembled with 6 mol ṡ L-1 KOH electrolyte. The electrochemical properties were studied by galvanostatic charge-discharge and cyclic voltammetry. The results indicated that although the BET surface area of modified ACs decreased, the functional groups were introduced and the ash contents were reduced on the surface of ACs, receiving larger specific capacitance to initial AC. The specific capacitance of ACs modified with HCl, H2SO4, HF and HNO3 increased by 31.4%, 23%, 21% and 11.6%, respectively.

Study of surface activity of piroxicam at the interface of palm oil esters and various aqueous phases.

Science.gov (United States)

Abdulkarim, Muthanna Fawzy; Abdullah, Ghassan Zuhair; Chitneni, Mallikarjun; Yam, Mun Fei; Mahdi, Elrashid Saleh; Salman, Ibrahim Muhammad; Ameer, Omar Ziad; Sattar, Munavvar Abdul; Basri, Mahiran; Noor, Azmin Mohd

2012-04-01

The surface activity of some non-steroidal anti-inflammatory agents like ibuprofen was investigated extensively. This fact has attracted the researchers to extend this behavior to other agents like piroxicam. Piroxicam molecules are expected to orient at the interface of oil and aqueous phase. The aim of this study was, firstly, to assess the surface and interfacial tension behaviour of newly synthesised palm oil esters and various pH phosphate buffers. Furthermore, the surface and interfacial tension activity of piroxicam was studied. All the measurements of surface and interfacial tension were made using the tensiometer. The study revealed that piroxicam has no effect on surface tension values of all pH phosphate buffers and palm oil esters. Similarly, various concentrations of piroxicam did not affect the interfacial tensions between the oil phase and the buffer phases. Accordingly, the interfacial tension values of all mixtures of oil and phosphate buffers were considerably high which indicates the immiscibility. It could be concluded that piroxicam has no surface activity. Additionally, there is no surface pressure activity of piroxicam at the interface of plam oil esters and phosphate buffers in the presence of Tweens and Spans.

Temperature effects on surface activity and application in oxidation ...

Indian Academy of Sciences (India)

Unknown

Abstract. The γcmc values of CTAB–SDS decrease from 63⋅67 mN/m at 10°C to 36⋅38 mN/m at 90°C, slightly lower than those of either CTAB or SDS. Correspondingly, the CMC of CTAB–SDS decreases almost by half. The increase of surface activity of CTAB–SDS can be attributed to the relatively weak electrostatic ...

Polyaniline hybridized surface defective ZnO nanorods with long-term stable photoelectrochemical activity

International Nuclear Information System (INIS)

Bera, Susanta; Khan, Hasmat; Biswas, Indranil; Jana, Sunirmal

2016-01-01

Highlights: • Polyaniline (PANI) hybridized ZnO nanorods was synthesized by solution method. • Surface defects were found in the nanorods. • The hybrid material exhibited an enhancement in visible light absorption. • A long-term stable photoelectrochemical activity of the material was found. • Advancement in the properties would be PANI hybridization and surface defects. - Abstract: We report surfactant/template free precursor solution based synthesis of polyaniline (PANI) hybridized surface defective ZnO nanorods by a two-step process. Initially, ZnO nanorods have been prepared at 95 °C, followed by hybridization (coating) of PANI onto the ZnO via in situ polymerization of aniline monomer, forming ZnO-PANI nanohybrid (ZP). The structural properties of ZP have been analyzed by X-ray diffraction (XRD) and transmission electron microscopic (TEM) studies. The presence of surface defects especially the oxygen vacancies in ZnO has been characterized by photoluminescence emission, high resolution TEM, X-ray photoelectron spectroscopy (XPS) and micro-Raman spectral measurements. The chemical interaction of PANI with ZnO has been examined by Fourier transform infrared (FTIR) and XPS analyses. A significant enhancement in visible absorption of ZP sample is found as evidenced from UV–vis diffused reflectance spectral study. BET nitrogen adsorption-desorption isotherm shows an improved textural property (pore size, pore volume) of ZP. Moreover, a long-term stable photoelectrochemical activity (PEC) of ZP is found compare to pristine ZnO. The synergic effect of PANI hybridization and the presence of surface defects in ZnO NRs can enhance the PEC by prolonging the recombination rate of photogenerated charge carriers. The effect can also provide large number of active sites to make electrolyte diffusion and mass transportation easier in the nanohybrid. This simple synthesis strategy can be adopted for PANI hybridization with different metal oxide semiconductors

Polyaniline hybridized surface defective ZnO nanorods with long-term stable photoelectrochemical activity

Energy Technology Data Exchange (ETDEWEB)

Bera, Susanta; Khan, Hasmat [Sol-Gel Division, CSIR-Central Glass and Ceramic Research Institute (CSIR-CGCRI), 196 Raja S.C. Mullick Road, P.O. Jadavpur University, Kolkata 700 032, West Bengal (India); Biswas, Indranil [Materials Characterization and Instrumentation Division, CSIR-Central Glass and Ceramic Research Institute (CSIR-CGCRI), 196 Raja S.C. Mullick Road, P.O. Jadavpur University, Kolkata 700 032, West Bengal (India); Jana, Sunirmal, E-mail: sjana@cgcri.res.in [Sol-Gel Division, CSIR-Central Glass and Ceramic Research Institute (CSIR-CGCRI), 196 Raja S.C. Mullick Road, P.O. Jadavpur University, Kolkata 700 032, West Bengal (India)

2016-10-15

Highlights: • Polyaniline (PANI) hybridized ZnO nanorods was synthesized by solution method. • Surface defects were found in the nanorods. • The hybrid material exhibited an enhancement in visible light absorption. • A long-term stable photoelectrochemical activity of the material was found. • Advancement in the properties would be PANI hybridization and surface defects. - Abstract: We report surfactant/template free precursor solution based synthesis of polyaniline (PANI) hybridized surface defective ZnO nanorods by a two-step process. Initially, ZnO nanorods have been prepared at 95 °C, followed by hybridization (coating) of PANI onto the ZnO via in situ polymerization of aniline monomer, forming ZnO-PANI nanohybrid (ZP). The structural properties of ZP have been analyzed by X-ray diffraction (XRD) and transmission electron microscopic (TEM) studies. The presence of surface defects especially the oxygen vacancies in ZnO has been characterized by photoluminescence emission, high resolution TEM, X-ray photoelectron spectroscopy (XPS) and micro-Raman spectral measurements. The chemical interaction of PANI with ZnO has been examined by Fourier transform infrared (FTIR) and XPS analyses. A significant enhancement in visible absorption of ZP sample is found as evidenced from UV–vis diffused reflectance spectral study. BET nitrogen adsorption-desorption isotherm shows an improved textural property (pore size, pore volume) of ZP. Moreover, a long-term stable photoelectrochemical activity (PEC) of ZP is found compare to pristine ZnO. The synergic effect of PANI hybridization and the presence of surface defects in ZnO NRs can enhance the PEC by prolonging the recombination rate of photogenerated charge carriers. The effect can also provide large number of active sites to make electrolyte diffusion and mass transportation easier in the nanohybrid. This simple synthesis strategy can be adopted for PANI hybridization with different metal oxide semiconductors

The preparation, surface structure, zeta potential, surface charge density and photocatalytic activity of TiO2 nanostructures of different shapes

Science.gov (United States)

Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali

2013-09-01

Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO2 catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na2Ti2O5·H2O) particles (W = 9-12 nm and L = 82-115 nm) and rice like pure anatase-TNR particles (W = 8-13 nm and L = 81-134 nm) are obtained by the hydrothermal treatment of P25-TiO2 with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = -2.82 (P25-TiO2), -13.5 (TNT) and -22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C9H10ClN5O2) degradation to CO2 formation under UV irradiation because of its largest surface area 176 m2 g-1 among the catalysts studied.

Antimicrobial activity of transition metal acid MoO3 prevents microbial growth on material surfaces

International Nuclear Information System (INIS)

Zollfrank, Cordt; Gutbrod, Kai; Wechsler, Peter; Guggenbichler, Josef Peter

2012-01-01

Serious infectious complications of patients in healthcare settings are often transmitted by materials and devices colonised by microorganisms (nosocomial infections). Current strategies to generate material surfaces with an antimicrobial activity suffer from the consumption of the antimicrobial agent and emerging multidrug-resistant pathogens amongst others. Consequently, materials surfaces exhibiting a permanent antimicrobial activity without the risk of generating resistant microorganisms are desirable. This publication reports on the extraordinary efficient antimicrobial properties of transition metal acids such as molybdic acid (H 2 MoO 4 ), which is based on molybdenum trioxide (MoO 3 ). The modification of various materials (e.g. polymers, metals) with MoO 3 particles or sol–gel derived coatings showed that the modified materials surfaces were practically free of microorganisms six hours after contamination with infectious agents. The antimicrobial activity is based on the formation of an acidic surface deteriorating cell growth and proliferation. The application of transition metal acids as antimicrobial surface agents is an innovative approach to prevent the dissemination of microorganisms in healthcare units and public environments. Highlights: ► The presented modifications of materials surfaces with MoO 3 are non-cytotoxic and decrease biofilm growth and bacteria transmission. ► The material is insensitive towards emerging resistances of bacteria. ► Strong potential to reduce spreading of infectious agents on inanimate surfaces.

Activity of processes on the visible surface of planets of Solar system

Science.gov (United States)

Vidmachenko, A. P.

2016-05-01

According to modern concepts bodies of the solar system formed from a single cloud of gas and dust. Calculations show that in the protoplanetary nebula where the temperature is lowered to 1600 K - appeared the first type of metal (aluminum and titanium) and metal oxides in the form of dust particles. With further decreasing temperature of the nebula to 1400 K - appeared also dust of iron and iron-nikel alloy; at 1300 K - appear solid silicates; magnesium minerals formed at T 1200 K. These components are material for the formation of basaltic rocks. At temperatures T 300 K begins to form water molecules. At 100-200 K in a remote part of the nebula - ammonia, methane and their ice are formed. In the outer part of Solar system this ices are now preserved in comet nuclei and in the icy satellites of giant planets. During T 400 million years after the formation of the Sun, at first - from dust component of the protoplanetary cloud was formed many intermediate bodies with the size of hundreds kilometers. Their gravitational interaction was reinforced in process of their grow. The bodies, which were growing fastest, they became the embryos of the future planets. All bodies of the solar system in different degrees show manifestations of different types of activity processes on the surface or at the level of the visible clouds. This activity depends on the distance of a particular body from the Sun, surface chemical composition, physical conditions at the surface and so on. The farther away from the Sun is the object, the temperature of its visible surface is lower, and by that more interesting is the set of processes, of chemical and physical transformations that there is possible to register. The surface of each planets of Solar system is very active in a variety of set temperature and chemical composition

Selective metallization of polymers using laser induced surface activation (LISA)—characterization and optimization of porous surface topography

DEFF Research Database (Denmark)

Zhang, Yang; Hansen, Hans Nørgaard; De Grave, Arnaud

2011-01-01

Laser induced selective activation (LISA) is a molded interconnected devices technique for selective metallization of polymers. On the working piece, only the laser-machined area can be metalized in the subsequent plating. The principle of the technology is introduced. Surface analysis was perfor...

Effect of the grain size of the soil on the measured activity and variation in activity in surface and subsurface soil samples

International Nuclear Information System (INIS)

Sulaiti, H.A.; Rega, P.H.; Bradley, D.; Dahan, N.A.; Mugren, K.A.; Dosari, M.A.

2014-01-01

Correlation between grain size and activity concentrations of soils and concentrations of various radionuclides in surface and subsurface soils has been measured for samples taken in the State of Qatar by gamma-spectroscopy using a high purity germanium detector. From the obtained gamma-ray spectra, the activity concentrations of the 238U (226Ra) and /sup 232/ Th (/sup 228/ Ac) natural decay series, the long-lived naturally occurring radionuclide 40 K and the fission product radionuclide 137CS have been determined. Gamma dose rate, radium equivalent, radiation hazard index and annual effective dose rates have also been estimated from these data. In order to observe the effect of grain size on the radioactivity of soil, three grain sizes were used i.e., smaller than 0.5 mm; smaller than 1 mm and greater than 0.5 mm; and smaller than 2 mm and greater than 1 mm. The weighted activity concentrations of the 238U series nuclides in 0.5-2 mm grain size of sample numbers was found to vary from 2.5:f:0.2 to 28.5+-0.5 Bq/kg, whereas, the weighted activity concentration of 4 degree K varied from 21+-4 to 188+-10 Bq/kg. The weighted activity concentrations of 238U series and 4 degree K have been found to be higher in the finest grain size. However, for the 232Th series, the activity concentrations in the 1-2 mm grain size of one sample were found to be higher than in the 0.5-1 mm grain size. In the study of surface and subsurface soil samples, the activity concentration levels of 238 U series have been found to range from 15.9+-0.3 to 24.1+-0.9 Bq/kg, in the surface soil samples (0-5 cm) and 14.5+-0.3 to 23.6+-0.5 Bq/kg in the subsurface soil samples (5-25 cm). The activity concentrations of 232Th series have been found to lie in the range 5.7+-0.2 to 13.7+-0.5 Bq/kg, in the surface soil samples (0-5 cm)and 4.1+-0.2 to 15.6+-0.3 Bq/kg in the subsurface soil samples (5-25 cm). The activity concentrations of 4 degree K were in the range 150+-8 to 290+-17 Bq/kg, in the surface

The Ice Nucleation Activity of Surface Modified Soot

Science.gov (United States)

Häusler, Thomas; Witek, Lorenz; Felgitsch, Laura; Hitzenberger, Regina; Grothe, Hinrich

2017-04-01

The ice nucleation efficiency of many important atmospheric particles remains poorly understood. Since soot is ubiquitous in the Earth's troposphere, they might have the potential to significantly impact the Earth's climate (Finlayson-Pitts and Pitts, 2000; Seinfeld and Pandis, 1998). Here we present the ice nucleation activity (INA) in immersion freezing mode of different types of soot. Therefor a CAST (combustion aerosol standard) generator was used to produce different kinds of soot samples. The CAST generator combusts a propane-air-mixture and deposits thereby produced soot on a polyvinyl fluoride filter. By varying the propane to air ratio, the amount of organic portion of the soot can be varied from black carbon (BC) with no organic content to brown carbon (BrC) with high organic content. To investigate the impact of functional sites of ice nuclei (IN), the soot samples were exposed to NO2 gas for a certain amount of time (30 to 360 minutes) to chemically modify the surface. Immersion freezing experiments were carried out in a unique reaction gadget. In this device a water-in-oil suspension (with the soot suspended in the aqueous phase) was cooled till the freezing point and was observed through a microscope (Pummer et al., 2012; Zolles et al., 2015) It was found that neither modified nor unmodified BC shows INA. On the contrary, unmodified BrC shows an INA at -32˚ C, which can be increased up to -20˚ C. The INA of BrC depends on the duration of NO2- exposure. To clarify the characteristics of the surface modifications, surface sensitive analysis like infrared spectroscopy and X-ray photoelectron spectroscopy were carried out. Finlayson-Pitts, B. J. and Pitts, J. N. J.: Chemistry of the Upper and Lower Atmosphere, Elsevier, New York, 2000. Pummer, B. G., Bauer, H., Bernardi, J., Bleicher, S., and Grothe, H.: Suspendable macromolecules are responsible for ice nucleation activity of birch and conifer pollen, Atmos Chem Phys, 12, 2541-2550, 2012. Seinfeld, J

Disease-linked mutations in factor H reveal pivotal role of cofactor activity in self-surface-selective regulation of complement activation.

Science.gov (United States)

Kerr, Heather; Wong, Edwin; Makou, Elisavet; Yang, Yi; Marchbank, Kevin; Kavanagh, David; Richards, Anna; Herbert, Andrew P; Barlow, Paul N

2017-08-11

Spontaneous activation enables the complement system to respond very rapidly to diverse threats. This activation is efficiently suppressed by complement factor H (CFH) on self-surfaces but not on foreign surfaces. The surface selectivity of CFH, a soluble protein containing 20 complement-control protein modules (CCPs 1-20), may be compromised by disease-linked mutations. However, which of the several functions of CFH drives this self-surface selectivity remains unknown. To address this, we expressed human CFH mutants in Pichia pastoris We found that recombinant I62-CFH (protective against age-related macular degeneration) and V62-CFH functioned equivalently, matching or outperforming plasma-derived CFH, whereas R53H-CFH, linked to atypical hemolytic uremic syndrome (aHUS), was defective in C3bBb decay-accelerating activity (DAA) and factor I cofactor activity (CA). The aHUS-linked CCP 19 mutant D1119G-CFH had virtually no CA on (self-like) sheep erythrocytes ( E S ) but retained DAA. The aHUS-linked CCP 20 mutant S1191L/V1197A-CFH (LA-CFH) had dramatically reduced CA on E S but was less compromised in DAA. D1119G-CFH and LA-CFH both performed poorly at preventing complement-mediated hemolysis of E S PspCN, a CFH-binding Streptococcus pneumoniae protein domain, binds CFH tightly and increases accessibility of CCPs 19 and 20. PspCN did not improve the DAA of any CFH variant on E S Conversely, PspCN boosted the CA, on E S , of I62-CFH, R53H-CFH, and LA-CFH and also enhanced hemolysis protection by I62-CFH and LA-CFH. We conclude that CCPs 19 and 20 are critical for efficient CA on self-surfaces but less important for DAA. Exposing CCPs 19 and 20 with PspCN and thus enhancing CA on self-surfaces may reverse deficiencies of some CFH variants. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Quaternary Geology and Surface Faulting Hazard: Active and Capable Faults in Central Apennines, Italy

Science.gov (United States)

Falcucci, E.; Gori, S.

2015-12-01

The 2009 L'Aquila earthquake (Mw 6.1), in central Italy, raised the issue of surface faulting hazard in Italy, since large urban areas were affected by surface displacement along the causative structure, the Paganica fault. Since then, guidelines for microzonation were drew up that take into consideration the problem of surface faulting in Italy, and laying the bases for future regulations about related hazard, similarly to other countries (e.g. USA). More specific guidelines on the management of areas affected by active and capable faults (i.e. able to produce surface faulting) are going to be released by National Department of Civil Protection; these would define zonation of areas affected by active and capable faults, with prescriptions for land use planning. As such, the guidelines arise the problem of the time interval and general operational criteria to asses fault capability for the Italian territory. As for the chronology, the review of the international literature and regulatory allowed Galadini et al. (2012) to propose different time intervals depending on the ongoing tectonic regime - compressive or extensional - which encompass the Quaternary. As for the operational criteria, the detailed analysis of the large amount of works dealing with active faulting in Italy shows that investigations exclusively based on surface morphological features (e.g. fault planes exposition) or on indirect investigations (geophysical data), are not sufficient or even unreliable to define the presence of an active and capable fault; instead, more accurate geological information on the Quaternary space-time evolution of the areas affected by such tectonic structures is needed. A test area for which active and capable faults can be first mapped based on such a classical but still effective methodological approach can be the central Apennines. Reference Galadini F., Falcucci E., Galli P., Giaccio B., Gori S., Messina P., Moro M., Saroli M., Scardia G., Sposato A. (2012). Time

Development of surface plasmon resonance sensor for determining zinc ion using novel active nanolayers as probe.

Science.gov (United States)

Fen, Yap Wing; Yunus, W Mahmood Mat; Talib, Zainal Abidin; Yusof, Nor Azah

2015-01-05

In this study, novel active nanolayers in combination with surface plasmon resonance (SPR) system for zinc ion (Zn(2+)) detection has been developed. The gold surface used for the SPR system was modified with the novel developed active nanolayers, i.e. chitosan and chitosan-tetrabutyl thiuram disulfide (chitosan-TBTDS). Both chitosan and chitosan-TBTDS active layers were fabricated on the gold surface by spin coating technique. The system was used to monitor SPR signal for Zn(2+) in aqueous media with and without sensitivity enhancement by TBTDS. For both active nanolayers, the shift of resonance angle is directly proportional to the concentration of Zn(2+) in aqueous media. The higher shift of resonance angle was obtained for chitosan-TBTDS active nanolayer due to a specific binding of TBTDS with Zn(2+). The chitosan-TBTDS active nanolayer enhanced the sensitivity of detection down to 0.1 mg/l and also induced a selective detection towards Zn(2+). Copyright © 2014 Elsevier B.V. All rights reserved.

Alkali treatment of microrough titanium surfaces affects macrophage/monocyte adhesion, platelet activation and architecture of blood clot formation

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V Milleret

2011-05-01

Full Text Available Titanium implants are most commonly used for bone augmentation and replacement due to their favorable osseointegration properties. Here, hyperhydrophilic sand-blasted and acid-etched (SBA titanium surfaces were produced by alkali treatment and their responses to partially heparinized whole human blood were analyzed. Blood clot formation, platelet activation and activation of the complement system was analyzed revealing that exposure time between blood and the material surface is crucial as increasing exposure time results in higher amount of activated platelets, more blood clots formed and stronger complement activation. In contrast, the number of macrophages/monocytes found on alkali-treated surfaces was significantly reduced as compared to untreated SBA Ti surfaces. Interestingly, when comparing untreated to modified SBA Ti surfaces very different blood clots formed on their surfaces. On untreated Ti surfaces blood clots remain thin (below 15 mm, patchy and non-structured lacking large fibrin fiber networks whereas blood clots on differentiated surfaces assemble in an organized and layered architecture of more than 30 mm thickness. Close to the material surface most nucleated cells adhere, above large amounts of non-nucleated platelets remain entrapped within a dense fibrin fiber network providing a continuous cover of the entire surface. These findings might indicate that, combined with findings of previous in vivo studies demonstrating that alkali-treated SBA Ti surfaces perform better in terms of osseointegration, a continuous and structured layer of blood components on the blood-facing surface supports later tissue integration of an endosseous implant.

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

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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.

Synthesis of Pt-Ru PSB-Py catalysis by {gamma}-irradiation and their electrocatalytic efficiency for methanol oxidation

Energy Technology Data Exchange (ETDEWEB)

Yoon, Jung Ah; Sim, Kwang Sik; Choi, Seong Ho [Hannam University, Daejeon (Korea, Republic of); Jung, Sung Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2009-09-15

We report here that deposition of Pt-Ru catalysis on the surface of core-shell conductive balls by radiation-chemical reduction of Pt and Ru ions, in order to use as catalysis in a fuel cell. The poly(styrene-co-4-vinylphenylboronic acid)-pyrrole (PSB-Py) with core-shell structure was obtained by in situ polymerization of pyrrole in the presence of the poly(styrene-co-4-vinylphenylboronic acid) (PSB). Subsequently, Pt-Ru catalysis were deposited onto PSB-Py ball by {gamma}-irradiation, in the presence/absence of poly(vinypyrolidone) (PVP) to prepare electrocatalysis for a fuel cell. The catalytic efficiency of Pt-Ru PSB-Py catalyst was examined for carbon monoxide (CO) stripping and methanol oxidation.

Synthesis of Pt-Ru PSB-Py catalysis by γ-irradiation and their electrocatalytic efficiency for methanol oxidation

International Nuclear Information System (INIS)

Yoon, Jung Ah; Sim, Kwang Sik; Choi, Seong Ho; Jung, Sung Hee

2009-01-01

We report here that deposition of Pt-Ru catalysis on the surface of core-shell conductive balls by radiation-chemical reduction of Pt and Ru ions, in order to use as catalysis in a fuel cell. The poly(styrene-co-4-vinylphenylboronic acid)-pyrrole (PSB-Py) with core-shell structure was obtained by in situ polymerization of pyrrole in the presence of the poly(styrene-co-4-vinylphenylboronic acid) (PSB). Subsequently, Pt-Ru catalysis were deposited onto PSB-Py ball by γ-irradiation, in the presence/absence of poly(vinypyrolidone) (PVP) to prepare electrocatalysis for a fuel cell. The catalytic efficiency of Pt-Ru PSB-Py catalyst was examined for carbon monoxide (CO) stripping and methanol oxidation

Preparation of polymer composite nanomembranes with a conductivity asymmetry

International Nuclear Information System (INIS)

Kravets, L.I.; Dmitriev, S.N.; Satulu, B.; Mitu, B.; Dinescu, G.

2009-01-01

The structure and charge transport properties of the poly(ethylene terephthalate) track membrane modified by a pyrrole plasma have been studied. It was found that polymer deposition on the surface of a track membrane via the plasma polymerization of pyrrole results in the creation of a composite nanomembrane that, in the case of the formation of a semipermeable layer covering the pores, possesses conductivity asymmetry in electrolyte solutions - a rectification effect similar to that of a p-n junction in semiconductors. It is caused by presence in the membrane of two layers with different functional groups and also by the pore geometry. Such a type of membranes can be used for creation of chemical and biochemical sensors

Factors Influencing NO2 Adsorption/Reduction on Microporous Activated Carbon: Porosity vs. Surface Chemistry

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Imen Ghouma

2018-04-01

Full Text Available The textural properties and surface chemistry of different activated carbons, prepared by the chemical activation of olive stones, have been investigated in order to gain insight on the NO2 adsorption mechanism. The parent chemical activated carbon was prepared by the impregnation of olive stones in phosphoric acid followed by thermal carbonization. Then, the textural properties and surface chemistry were modified by chemical treatments including nitric acid, sodium hydroxide and/or a thermal treatment at 900 °C. The main properties of the parent and modified activated carbons were analyzed by N2-adsorption, scanning electron microscopy (SEM, and Fourier transform infrared spectroscopy (FTIR techniques, in order to enlighten the modifications issued from the chemical and thermal treatments. The NO2 adsorption capacities of the different activated carbons were measured in fixed bed experiments under 500 ppmv NO2 concentrations at room temperature. Temperature programmed desorption (TPD was applied after adsorption tests in order to quantify the amount of the physisorbed and chemisorbed NO2. The obtained results showed that the development of microporosity, the presence of oxygen-free sites, and the presence of basic surface groups are key factors for the efficient adsorption of NO2.

The preparation, surface structure, zeta potential, surface charge density and photocatalytic activity of TiO2 nanostructures of different shapes

International Nuclear Information System (INIS)

Grover, Inderpreet Singh; Singh, Satnam; Pal, Bonamali

2013-01-01

Titania based nanocatalysts such as sodium titanates of different morphology having superior surface properties are getting wide importance in photocatalysis research. Despite having sodium (Na) contents and its high temperature synthesis (that generally deteriorate the photoreactivity), these Na-titanates often exhibit better photoactivity than P25-TiO 2 catalyst. Hence, this work demonstrated the influence of crystal structure, BET surface area, surface charge, zeta potential (ζ) and metal loading on the photocatalytic activity of as-prepared sodium titanate nanotube (TNT) and titania nanorod (TNR). Straw like hollow orthorhombic-TNT (Na 2 Ti 2 O 5 ·H 2 O) particles (W = 9–12 nm and L = 82–115 nm) and rice like pure anatase-TNR particles (W = 8–13 nm and L = 81–134 nm) are obtained by the hydrothermal treatment of P25-TiO 2 with NaOH, which in fact, altered the net surface charge of TNT and TNR particles. The observed ζ = −2.82 (P25-TiO 2 ), −13.5 (TNT) and −22.5 mV (TNR) are significantly altered by the Ag and Cu deposition. It has been found here that TNT displayed best photocatalytic activity for the imidacloprid insecticide (C 9 H 10 ClN 5 O 2 ) degradation to CO 2 formation under UV irradiation because of its largest surface area 176 m 2 g −1 among the catalysts studied.

Mass and Charge Transport in Electronically Conductive Polymers

Science.gov (United States)

1990-08-02

This method is based on coating an electrode surface with an insulating nitrile butadiene rubber ( NBR ). The electrolyte for polymerization (LiCIO4...in acetonitrile) etches channels through the NBR ; pyrrole is then polymerized in these channels. After polymerization the NBR is extracted away with

Surface-bound phosphatase activity in living hyphae of ectomycorrhizal fungi of Nothofagus obliqua.

Science.gov (United States)

Alvarez, Maricel; Godoy, Roberto; Heyser, Wolfgang; Härtel, Steffen

2004-01-01

We determined the location and the activity of surface-bound phosphomonoesterase (SBP) of five ectomycorrhizal (EM) fungi of Nothofagus oblique. EM fungal mycelium of Paxillus involutus, Austropaxillus boletinoides, Descolea antartica, Cenococcum geophilum and Pisolithus tinctorius was grown in media with varying concentrations of dissolved phosphorus. SBP activity was detected at different pH values (3-7) under each growth regimen. SBP activity was assessed using a colorimetric method based on the hydrolysis of p-nitrophenyl phosphate (pNPP) to p-nitrophenol phosphate (pNP) + P. A new technique involving confocal laser-scanning microscopy (LSM) was used to locate and quantify SBP activity on the hyphal surface. EM fungi showed two fundamentally different patterns of SBP activity in relation to varying environmental conditions (P-concentrations and pH). In the cases of D. antartica, A. boletinoides and C. geophilum, changes in SBP activity were induced primarily by changes in the number of SBP-active centers on the hyphae. In the cases of P. tinctorius and P. involutus, the number of SBP-active centers per μm hyphal length changed much less than the intensity of the SBP-active centers on the hyphae. Our findings not only contribute to the discussion about the role of SBP-active centers in EM fungi but also introduce LSM as a valuable method for studying EM fungi.

Development of a new analytical tool for assessing the mutagen 2-methyl-1,4-dinitro-pyrrole in meat products by LC-ESI-MS/MS.

Science.gov (United States)

Molognoni, Luciano; Daguer, Heitor; de Sá Ploêncio, Leandro Antunes; Yotsuyanagi, Suzana Eri; da Silva Correa Lemos, Ana Lucia; Joussef, Antonio Carlos; De Dea Lindner, Juliano

2018-08-01

The use of sorbate and nitrite in meat processing may lead to the formation of 2-methyl-1,4-dinitro-pyrrole (DNMP), a mutagenic compound. This work was aimed at developing and validating an analytical method for the quantitation of DNMP by liquid chromatography-tandem mass spectrometry. Full validation was performed in accordance to Commission Decision 2002/657/EC and method applicability was checked in several samples of meat products. A simple procedure, with low temperature partitioning solid-liquid extraction, was developed. The nitrosation during the extraction was monitored by the N-nitroso-DL-pipecolic acid content. Chromatographic separation was achieved in 8 min with di-isopropyl-3-aminopropyl silane bound to hydroxylated silica as stationary phase. Samples of bacon and cooked sausage yielded the highest concentrations of DNMP (68 ± 3 and 50 ± 3 μg kg -1 , respectively). The developed method proved to be a reliable, selective, and sensitive tool for DNMP measurements in meat products. Copyright © 2018 Elsevier B.V. All rights reserved.

Origins of the Unfavorable Activation and Reaction Energies of 1-Azadiene Heterocycles Compared to 2-Azadiene Heterocycles in Diels-Alder Reactions.

Science.gov (United States)

Fell, Jason S; Martin, Blanton N; Houk, K N

2017-02-17

The reactivities of butadiene, cyclopentadiene, furan, thiophene, pyrrole, and their 1-aza- and 2-aza-derivatives in Diels-Alder reactions with ethylene and fumaronitrile were investigated with density functional theory (M06-2X/6-311G(d,p)). The activation free energies for the Diels-Alder reactions of cyclic 1-azadienes are 10-14 kcal mol -1 higher than those of cyclic 2-azadienes, and the reaction free energies are 17-20 kcal mol -1 more endergonic. The distortion/interaction model shows that the increased activation energies of cyclic 1-azadienes originate from increased transition state distortion energies and unfavorable interaction energies, arising from addition to the nitrogen terminus of the C═N bond.

Shielding factors for gamma radiation from activity deposited on structures and ground surfaces

International Nuclear Information System (INIS)

Hedemann Jensen, P.

1982-11-01

This report describes a computer model that calculates shielding factors for indoor residence in multistorey and single-family houses for gamma radiation from activity despoited on roofs, outer walls, and ground surfaces. The dimensions of the buildings including window areas and the nearby surroundings has to be speficied in the calculations. Shielding factors can be calculated for different photon energies and for a uniform surface activity distribution as well as for separate activity on roof, outer wall, and ground surface achieved from decontamination or different deposition velocities. For a given area with a known distribution of different houses a weighted shielding factor can be calculated as well as a time-averaged one based on a given residence time distribution for work/school, home, outdoors, and transportation. Calculated shielding factors are shown for typical Danish houses. To give an impression of the sensitivity of the shielding factor on the parameters used in the model, variations were made in some of the most important parameters: wall thickness, road and ground width, percentage of outer wall covered by windows, photon energy, and decontamination percentage for outer walls, ground and roofs. The uncertainity of the calculations is discussed. (author)

High-Surface-Area, Emulsion-Templated Carbon Foams by Activation of polyHIPEs Derived from Pickering Emulsions

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Robert T. Woodward

2016-09-01

Full Text Available Carbon foams displaying hierarchical porosity and excellent surface areas of >1400 m2/g can be produced by the activation of macroporous poly(divinylbenzene. Poly(divinylbenzene was synthesized from the polymerization of the continuous, but minority, phase of a simple high internal phase Pickering emulsion. By the addition of KOH, chemical activation of the materials is induced during carbonization, producing Pickering-emulsion-templated carbon foams, or carboHIPEs, with tailorable macropore diameters and surface areas almost triple that of those previously reported. The retention of the customizable, macroporous open-cell structure of the poly(divinylbenzene precursor and the production of a large degree of microporosity during activation leads to tailorable carboHIPEs with excellent surface areas.

Surface activation of MnNb{sub 2}O{sub 6} nanosheets by oxalic acid for enhanced photocatalysis

Energy Technology Data Exchange (ETDEWEB)

Wu, Junshu; Wang, Jinshu, E-mail: wangjsh@bjut.edu.cn; Li, Hongyi; Li, Yongli; Du, Yucheng; Yang, Yilong; Jia, Xinjian

2017-05-01

Graphical abstract: Visible light driven photoreduction of Cr(VI) over MnNb{sub 2}O{sub 6} nanosheets is enhanced via oxalic acid surface complex to generate activation layer. - Highlights: • MnNb{sub 2}O{sub 6} nanosheets are crystallized by a surface capping route of sulfonate groups. • Oxalic acid on MnNb{sub 2}O{sub 6} nanosheets forms an excited surface complex hybrid layer. • Surface activation enhances visible-light induced reduction of Cr(VI) into Cr(III). - Abstract: MnNb{sub 2}O{sub 6} nanosheets (P-MNOs) is selectively crystallized by using surface capping ligand with functional sulfonate group (sodium dodecyl benzene sulphonate), which binds to the (131) surface of MnNb{sub 2}O{sub 6} inducing the morphology-controlled crystallization of MnNb{sub 2}O{sub 6} materials. Surface modification of photoactive P-MNOs with electron-rich oxalic acid ligands establishes an excited surface complex layer on phase-pure P-MNO as evidenced by spectroscopic analyses (FT-IR, UV–vis, Raman, PL, etc.), and thus more efficiently photocatalyzes the reduction of Cr(VI) into Cr(III) than solely P-MNOs or oxalic acid under visible light (λ > 420 nm) via a ligand-to-metal interfacial electron transfer pathway. However, the interaction between oxalic acid and MnNb{sub 2}O{sub 6} is highly dependent upon the morphology of solid MnNb{sub 2}O{sub 6} substrate due to the higher surface-area-to-volume ratio and higher surface activity of (131) planes in the sheet-like morphology. This study could assist the construction of stable niobate material systems to allow a versatile solid surface activation for establishing more energy efficient and robust catalysis process under visible light.

Observation of the Strong Electronic Coupling in Near-Infrared-Absorbing Tetraferrocene aza-Dipyrromethene and aza-BODIPY with Direct Ferrocene-α- and Ferrocene-β-Pyrrole Bonds: Toward Molecular Machinery with Four-Bit Information Storage Capacity.

Science.gov (United States)

Zatsikha, Yuriy V; Holstrom, Cole D; Chanawanno, Kullapa; Osinski, Allen J; Ziegler, Christopher J; Nemykin, Victor N

2017-01-17

The 1,3,7,9-tetraferrocenylazadipyrromethene (3) and the corresponding 1,3,5,7-tetraferrocene aza-BODIPY (4) were prepared via three and four synthetic steps, respectively, starting from ferrocenecarbaldehyde using the chalcone-type synthetic methodology. The novel tetra-iron compounds have ferrocene groups directly attached to both the α- and the β-pyrrolic positions, and the shortest Fe-Fe distance determined by X-ray crystallography for 3 was found to be ∼6.98 Å. These new compounds were characterized by UV-vis, nuclear magnetic resonance, and high-resolution electrospray ionization mass spectrometry methods, while metal-metal couplings in these systems were probed by electro- and spectroelectrochemistry, chemical oxidations, and Mössbauer spectroscopy. Electrochemical data are suggestive of the well-separated stepwise oxidations of all four ferrocene groups in 3 and 4, while spectroelectrochemical and chemical oxidation experiments allowed for characterization of the mixed-valence forms in the target compounds. Intervalence charge-transfer band analyses indicate that the mixed-valence [3] + and [4] + complexes belong to the weakly coupled class II systems in the Robin-Day classification. This interpretation was further supported by Mössbauer spectroscopy in which two individual doublets for Fe(II) and Fe(III) centers were observed in room-temperature experiments for the mixed-valence [3] n+ and [4] n+ species (n = 1-3). The electronic structure, redox properties, and UV-vis spectra of new systems were correlated with Density Functional Theory (DFT) and time-dependent DFT calculations (TDDFT), which are suggestive of a ferrocene-centered highest occupied molecular orbital and chromophore-centered lowest unoccupied molecular orbital in 3 and 4 as well as predominant spin localization at the ferrocene fragment attached to the α-pyrrolic positions in [3] + and [4] + .

Modification of polymer surfaces to enhance enzyme activity and stability

DEFF Research Database (Denmark)

Hoffmann, Christian

Enzyme immobilization is an important concept for the development of improved biocatalytic processes, primarily through facilitated separation procedures. However, enzyme immobilization usually comes at a price of reduced biocatalytic activity. For this reason, different immobilization methods have...... already been developed, combining the same goal to improve enzyme activity, stability and selectivity. Polymer materials have shown, due to their easy processibility and versatile properties, high potential as enzyme support. However, in order to achieve improved enzyme performance, the combination...... on their tailored surface modification in order to obtain improved enzyme-support systems. Firstly, an off-stoichiometric thiol-ene (OSTE) thermosetting material was used for the development of a screening platform allowing the investigation of micro-environmental effects and their impact on the activity...

Autodisplay of an avidin with biotin-binding activity on the surface of Escherichia coli.

Science.gov (United States)

Pardavé-Alejandre, H D; Alvarado-Yaah, J E; Pompa-Mera, E N; Muñoz-Medina, J E; Sárquiz-Martínez, B; Santacruz-Tinoco, C E; Manning-Cela, R G; Ortíz-Navarrete, V; López-Macías, C; González-Bonilla, C R

2018-03-01

To display a recombinant avidin fused to the autotransporter ShdA to bind biotinylated molecules on the surface of Escherichia coli. Two chimeric protein constructs containing avidin fused to the autotransporter ShdA were expressed on the surface of Escherichia coli DH5α. One fusion protein contained 476 amino acids of the ShdA α and β domains, whereas the second consisted of a 314 amino acid from α and truncated β domains. Protein production was verified by SDS-PAGE using an antibody to the molecular FLAG-tag. The surface display of the avidin-shdA fusion protein was confirmed by confocal microscopy and flow cytometry analysis, and the biotin-binding activity was evaluated by fluorescence microscopy and flow cytometry using biotin-4-fluorescein and biotinylated-ovalbumin (OVA). Expression of a recombinant avidin with biotin-binding activity on the surface of E. coli was achieved using the autotransporter ShdA. This system is an alternative to bind biotinylated molecules to E. coli.