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Sample records for titaniumiv oxide modified

  1. Biological consequences from interaction of nanosized titanium(iv) oxides with defined human blood components

    Science.gov (United States)

    Stella, Aaron

    The utility of engineered nanomaterials is growing, particularly the titanium(iv) oxide (titanium dioxide, TiO2) nanoparticles. TiO 2 is very useful for brightening paints, and coloring foods. Nano-sized TiO2 is also useful for sunscreens, cosmetics, and can be utilized as a photocatalyst. However, the nanometer size of the TiO2 nanoparticle is a characteristic that may contribute oxidative stress to red blood cells (RBCs) in humans. This study utilized screening methods to evaluate different forms of TiO2 nanoparticles which differ by primary particle size, specific surface area, crystalline phase, and surface polarity. RBCs are rich in the intracellular antioxidant glutathione (GSH). HPLC analysis revealed that some TiO2 nanoparticles caused oxidation of GSH to glutathione disulfide (GSSG). Vitamin E is a major membrane-bound antioxidant. Vitamin E levels were then determined by HPLC in the RBC membrane after exposure to TiO2 nanoparticles. The HPLC results showed that each nanoparticle oxidized RBC glutathione and membrane vitamin E at different rates. When hemoglobin was mixed with each TiO2 nanoparticle, hemoglobin was adsorbed at varying rates to the surface of the nanoparticles. Similarly, the aminothiol homocysteine was also adsorbed at different rates by the TiO2 nanoparticles. Using light microscopy, some TiO2 nanoparticles caused the formation of RBC aggregates which significantly changed the RBC morphology. The aggregation data was quantified using a hemacytometer. The TiO2 nanoparticles also caused hemolysis of RBCs. Hemolysis is considered to be a toxic endpoint for RBCs. Changes in the nucleated lymphocyte gene expression of certain oxidative stress genes were also observed using real-time polymerase chain reaction (qPCR). The data indicates that RBCs can ultimately be hemolyzed by biological oxidative damage resulting from a combination of oxidative mechanisms. Additionally, the TiO2 nanoparticles demonstrated the ability to adsorb biomolecules to

  2. Decomposition of aluminum oxide, titanium(IV) oxide and niobium(V) oxide by fusion with ammonium sulfate

    International Nuclear Information System (INIS)

    Hashiba, Minoru; Miura, Eiji; Nurishi, Yukio; Hibino, Taizo

    1980-01-01

    A decomposition method with ammonium sulfate for Al 2 O 3 , TiO 2 and Nb 2 O 5 is presented. Al 2 O 3 and TiO 2 were fused at 400 and 450 0 C, for 2 h and 1 h, respectively, in the presence of ammonium sulfate (oxide/ammonium sulfate = 1/20 in weight). The fused products were dissolved and extracted into 4N H 2 SO 4 aqueous solution by warming on the water bath or gently boiling on asbestos. The degree of decomposition by fusion was confirmed from the amount of the oxides recovered in the following manner; with the aid of filter pulp, the residue was completely separated by filtration and washed thoroughly by hot water. To the filtrate was added ammonia water in order to precipitate aluminum and titanium hydroxide. The precipitates were ignited in platinum crucible at 1000 0 C and weighed in oxide form. Nb 2 O 5 was fused at 400 0 C for 1 h in the presence of ammonium sulfate (niobium pentoxide/ammonium sulfate = 1/10 in weight). The fused product was extracted with 20% tartaric acid aqueous solution. The degree of decomposition by fusion was confirmed from the amount of the oxide recovered as follows; after separation of the residue by a filter paper with the aid of filter pulp and washed thoroughly by 2% tartaric acid aqueous solution, freshly prepared 6% aqueous solution of cupferron was added to the filtrate and the precipitate formed was filtered immediately. The precipitate was ignited in platinum crucible at 1000 0 C and weighed as Nb 2 O 5 . The recovery of Al 2 O 3 , TiO 2 and Nb 2 O 5 by the present method was (99.2 +- 0.4), (100.1 +- 0.2) and (100.1 +- 0.2)%, respectively. It is concluded that Al 2 O 3 , TiO 2 and Nb 2 O 5 could be completely decomposed with ammonium sulfate. (author)

  3. Synthesis of gadolinium doped titanium(IV) oxide and their photocatalytic activity to decrease chemical oxygen demand (COD) value of water pollutants

    Science.gov (United States)

    Eddy, Diana Rakhmawaty; Dwiyanti, Dina; Rahayu, Iman; Hastiawan, Iwan; Bahti, Husein H.

    2017-05-01

    Pesticides are widely used for the control of plant disease. Unfortunately they are highly toxic to terraneous and aquatic life; this is a particular problem in agricultural areas. TiO2 is widely used for pesticide control because of its photocatalytic activity, but it still has inadequacy in its wide band gap. Alternatively, the wide band gap of TiO2 could be narrowed by modification with rare earth element such as gadolinium, so the photocatalytic activity of TiO2could be significantly enhanced. The purpose of this experiment is to synthesize Gd/TiO2 and its application to reduce COD of water pollutants such as carbosulfan pesticide. This experiment is done by doping gadolinium oxide into titanium tetra isopropoxide by sol-gel method. The crystal structure is characterized by using XRD, shown anatase successfully obtained with the smallest crystallite size is 37.655 nm, indicated optimum calcination time is 4 hours. SEM-EDX result shown morphology of crystal is big aggregates. Photocatalytic activity is tested to carbosulfan pesticide, obtained the COD percent decreases up to 87.88%.

  4. Titanium(IV) in the organic-structure-directing-agent-free synthesis of hydrophobic and large-pore molecular sieves as redox catalysts.

    Science.gov (United States)

    Wang, Jingui; Yokoi, Toshiyuki; Kondo, Junko N; Tatsumi, Takashi; Zhao, Yanli

    2015-08-10

    Titanium(IV) incorporated into the framework of molecular sieves can be used as a highly active and sustainable catalyst for the oxidation of industrially important organic molecules. Unfortunately, the current process for the incorporation of titanium(IV) requires a large amount of expensive organic molecules used as organic-structure-directing agents (OSDAs), and this significantly increases the production costs and causes environmental problems owing to the removal of OSDAs by pyrolysis. Herein, an OSDA-free process was developed to incorporate titanium(IV) into BEA-type molecular sieves for the first time. More importantly, the hydrophobic environment and the robust, 3 D, and large pore structure of the titanium(IV)-incorporated molecular sieves fabricated from the OSDA-free process created a catalyst that was extremely active and selective for the epoxidation of bulky cyclooctene in comparison to Ti-incorporated BEA-type molecular sieves synthesized with OSDAs and commercial titanosilicate TS-1. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Modified iron oxide nanomaterials: Functionalization and application

    International Nuclear Information System (INIS)

    Bagheri, Samira; Julkapli, Nurhidayatullaili Muhd

    2016-01-01

    Iron oxide magnetic nanoparticles have aroused the interest of researchers of materials' chemistry due to its exceptional properties such as decent magnetic, electric, catalytic, biocompatibility, and low toxicity. However, these magnetic nanoparticles are predisposed towards aggregation and forming larger particles, due to its strong anisotropic dipolar interactions, particularly in the aqueous phase, consequently depriving them of dispersibility and particular properties, ultimately degrading their performance. Hence, this review focuses on modified magnetic nanoparticles that are stable, easily synthesized, possess a high surface area and could be facile-separated via magnetic forces, and are of low toxicity and costs for applications such as catalyst/catalyst support, food security, biomedical, and pollutant remediation. - Highlights: • Nanomagnetite is interesting due to its exceptional properties. • Nanomagnetite is predisposed towards aggregation and forming larger particles. • Modified nanomagnetite are stable, easily synthesized, possess high surface area. • Modified nanomagnetite got applications as catalyst/catalyst support.

  6. Modified iron oxide nanomaterials: Functionalization and application

    Energy Technology Data Exchange (ETDEWEB)

    Bagheri, Samira; Julkapli, Nurhidayatullaili Muhd

    2016-10-15

    Iron oxide magnetic nanoparticles have aroused the interest of researchers of materials' chemistry due to its exceptional properties such as decent magnetic, electric, catalytic, biocompatibility, and low toxicity. However, these magnetic nanoparticles are predisposed towards aggregation and forming larger particles, due to its strong anisotropic dipolar interactions, particularly in the aqueous phase, consequently depriving them of dispersibility and particular properties, ultimately degrading their performance. Hence, this review focuses on modified magnetic nanoparticles that are stable, easily synthesized, possess a high surface area and could be facile-separated via magnetic forces, and are of low toxicity and costs for applications such as catalyst/catalyst support, food security, biomedical, and pollutant remediation. - Highlights: • Nanomagnetite is interesting due to its exceptional properties. • Nanomagnetite is predisposed towards aggregation and forming larger particles. • Modified nanomagnetite are stable, easily synthesized, possess high surface area. • Modified nanomagnetite got applications as catalyst/catalyst support.

  7. Low-temperature creep of nanocrystalline titanium(IV) oxide

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, H.; Averback, R.S. (Dept. of Materials Sceince and Engineering, Univ. of Illinois, Urbana, IL (United States))

    1991-11-01

    This paper reports that nanocrystalline TiO[sub 2] with densities higher than 99% of rutile has been deformed in compression without fracture at temperatures between 600[degrees] and 800[degrees] C. The total strains exceed 0.6 at strain rates as high as 10[sup [minus]3] s[sup [minus]1]. The original average grain size of 40 nm increases during the creep deformation to final values in the range of 120 to 1000 nm depending on the temperature and total deformation. The stress exponent of the strain rate, n, is approximately 3 and the grain size dependence is d[sup [minus]q] with q in the range of 1 to 1.5. It is concluded that the creep deformation occurs by an interface reaction controlled mechanism.

  8. TiO2-graphene oxide nanocomposite as advanced photocatalytic materials

    Czech Academy of Sciences Publication Activity Database

    Štengl, Václav; Bakardjieva, Snejana; Matys Grygar, Tomáš; Bludská, Jana; Kormunda, M.

    2013-01-01

    Roč. 7, FEB (2013), s. 41 ISSN 1752-153X Institutional support: RVO:61388980 Keywords : graphene * titanium(IV) oxide * graphene oxide * photocatalysis Subject RIV: CA - Inorganic Chemistry Impact factor: 1.663, year: 2013

  9. Photocatalysis of Modified Transition Metal Oxide Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Batzill, Matthias

    2018-02-28

    The goal of this project has been to establish a cause-effect relationship for photocatalytic activity variations of different structures of the same material; and furthermore gain fundamental understanding on modification of photocatalysts by compositional or surface modifications. The reasoning is that gaining atomic scale understanding of how surface and bulk modifications alter the photo reactivity will lead to design principles for next generation photocatalysts. As a prototypical photocatalyst the research focused on TiO2 synthesized in well-defined single crystalline form to enable fundamental characterizations.We have obtained results in the following areas: (a) Preparation of epitaxial anataseTiO2 samples by pulsed laser deposition. (b) Comparison of hydrogen diffusion on different crystallographic surface. (c) Determining the stability of the TiO2(011)-2x1 reconstruction upon interactions with adsorbates. (d) Characterization of adsorption and (thermal and photo) reaction of molecules with nitro-endgroups, (e) Exploring the possibility of modifying planar model photocatalyst surfaces with graphene to enable fundamental studies on reported enhanced photocatalytic activities of graphene modified transition metal oxides, (f) gained fundamental understanding on the role of crystallographic polymorphs of the same material for their photocatalytic activities.

  10. Glucose Oxidation on Gold-modified Copper Electrode

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jieun; Pyo, Sung Gyu; Son, Hyungbin; Kim, Sookil [Chung-Ang Univ., Seoul (Korea, Republic of); Ahn, Sang Hyun; Son, Hyungbin [Korea Institute of Science and Technology, Seoul (Korea, Republic of)

    2013-09-15

    The activities of Au-modified Cu electrodes toward glucose oxidation are evaluated according to their fabrication conditions and physico-chemical properties. The Au-modified Cu electrodes are fabricated by the galvanic displacement of Au on a Cu substrate and the characteristics of the Au particles are controlled by adjusting the displacement time. From the glucose oxidation tests, it is found that the Au modified Cu has superior activity to the pure Au or Cu film, which is evidenced by the negative shift in the oxidation potential and enhanced current density during the electrochemical oxidation. Though the activity of the Au nanoparticles is a contributing factor, the enhanced activity of the Au-modified Cu electrode is due to the increased oxidation number of Cu through the electron transfer from Cu to more electronegative Au. The depletion of electron in Cu facilitates the oxidation of glucose. The stability of the Au-modified Cu electrode was also studied by chronoamperometry.

  11. Abrasive properties of modified oxides for finish polishing of steel

    Science.gov (United States)

    Koroleva, L. F.

    2017-12-01

    The study of modified chromium and aluminum oxides, demonstrates that finish polishing by modified hydroxocomplexes based on a solid solution of iron and aluminum oxides provide a surface nanoroughness of 0.02 to 0.005 µm for the hardened ShKh15 steel (American Standard AISI 52100).

  12. Fast and Straightforward Synthesis of Luminescent Titanium(IV Dioxide Quantum Dots

    Directory of Open Access Journals (Sweden)

    Václav Štengl

    2017-01-01

    Full Text Available The nucleus of titania was prepared by reaction of solution titanium oxosulphate with hydrazine hydrate. These titania nuclei were used for titania quantum dots synthesis by a simple and fast method. The prepared titanium(IV dioxide quantum dots were characterized by measurement of X-ray powder diffraction (XRD, X-ray photoelectron spectroscopy (XPS, atomic force microscopy (AFM, high-resolution electron microscopy (HRTEM, and selected area electron diffraction (SAED. The optical properties were determined by photoluminescence (PL spectra. The prepared titanium(IV dioxide quantum dots have the narrow range of UV excitation (365–400 nm and also a close range of emission maxima (450–500 nm.

  13. Mechanizm of propylene oxidation on modified cobalt-molybdenum catalysts

    International Nuclear Information System (INIS)

    Kutyrev, M.Yu.; Rozentuller, B.V.; Isaev, O.V.; Margolis, L.Ya.; Krylov, O.V.

    1977-01-01

    Effect is studied of additions of iron, copper, nickel, and vanadium oxides, introduced into cobalt, molybdate, on oxidation reactions of propylene to acrolein and acrylicacid. The principal parameters determining the activity and selectivity of oxidation of propylene and acrolein on modified cobalt molibdate are the structure, the type of Mo-O bond, and the nature of the electron transitions in the solid under the effect of adsorption of the reaction components

  14. Direct Coal Oxidation in Modified Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Gil, Vanesa; Ippolito, Davide

    2015-01-01

    Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon-carbonate s......Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon......-carbonate slurry or anode layer. The nature of the coal affects both open circuit voltage and power output. Highest OCV and power densities were observed for bituminous coal and by adding manganese oxide or praseodymium-doped ceria to the carbon/carbonate mixture. Comparing the carbon black fueled performance...... bituminous coal (73 mW/cm2). © 2015 ECS - The Electrochemical Society...

  15. Direct Coal Oxidation in Modified Solid Oxide Fuel Cells

    DEFF Research Database (Denmark)

    Deleebeeck, Lisa; Gil, Vanesa; Ippolito, Davide

    2017-01-01

    Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon-carbonate s......Hybrid direct carbon fuel cells employ a classical solid oxide fuel cell together with carbon dispersed in a carbonate melt on the anode side. In a European project, the utilization of various coals has been investigated with and without addition of an oxidation catalyst to the carbon......-carbonate slurry or anode layer. The nature of the coal affects both open circuit voltage and power output. Highest OCV and power densities were observed for bituminous coal and by adding manganese oxide or praseodymium-doped ceria to the carbon/carbonate mixture. Comparing the carbon black fueled performance...... bituminous coal (73 mW/cm2)....

  16. Palm fibers modified with zirconium oxide

    International Nuclear Information System (INIS)

    Martins, Giulia A.; Souza, J.V.C.; Goulart, Shane A.S.; Mulinari, Daniella R.; Suzuki, Paulo A.

    2011-01-01

    The objective of this work was to study the chemical modification of the fibers from palm with zirconium oxide in granulometric proportion different. The modification of the fibers by techniques scanning electron microscopy, X-ray diffractometry and infrared spectrophotometer was evaluated. Results showed that particle size of the fiber influenced in the modification. (author)

  17. Modified and Unmodified Zinc Oxide as Coagent in Elastomer Compounds

    Directory of Open Access Journals (Sweden)

    Kołodziejczak-Radzimska Agnieszka

    2014-09-01

    Full Text Available The aim of this work was to study the activity of unmodified and modified ZnO in the peroxide crosslinking of hydrogenated acrylonitrile-butadiene elastomer (HNBR and ethylene-propylene copolymer (EPM. In the first step, zinc oxide was obtained by emulsion precipitation. Maleic acid was introduced onto the surface of ZnO using an in situ method. The unmodified and modified zinc oxide was characterized using dispersive and morphological analysis, BET surface area analysis, and elemental, spectroscopic and thermal analysis. In the second stage of the research, the ZnO/MA systems were incorporated into the structure of elastomer compounds improving the kinetic and mechanical properties of vulcanizates. The proposed modification method had a favorable effect on the physicochemical properties of the zinc oxide and on the kinetic and mechanical properties of the vulcanizates. This study demonstrated that modification of zinc oxide by maleic acid is a promising technique.

  18. Electrocatalytic hydrazine oxidation on quinizarine modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Ardakani, Mohammad Mazloum [Department of Chemistry, Faculty of Science, Yazd University, Yazd (Iran, Islamic Republic of)]. E-mail: mazloum@yazduni.ac.ir; karami, Payam Ebrahimi [Department of Chemistry, Faculty of Science, Yazd University, Yazd (Iran, Islamic Republic of); Rahimi, Parvaneh [Department of Chemistry, Faculty of Science, Yazd University, Yazd (Iran, Islamic Republic of); Zare, Hamid Reza [Department of Chemistry, Faculty of Science, Yazd University, Yazd (Iran, Islamic Republic of); Naeimi, Hossein [Department of Chemistry, Faculty of Science, Kashan University, Kashan (Iran, Islamic Republic of)

    2007-06-10

    The electrocatalytic oxidation of hydrazine has been studied on glassy carbon modified by electrodeposition of quinizarine, using cyclic voltammetry and chronoamperometry techniques. It has been shown that the oxidation of hydrazine to nitrogen occurs at a potential where oxidation is not observed at the bare glassy carbon electrode. The apparent charge transfer rate constant and transfer coefficient for electron transfer between the electrode surface and immobilized quinizarine were calculated as 4.44 s{sup -1} and 0.66, respectively. The heterogenous rate constant for oxidation of hydrazine at the quinizarine modified electrode surface was also determined and found to be about 4.83 x 10{sup 3} M{sup -1} s{sup -1}. The diffusion coefficient of hydrazine was also estimated as 1.1 x 10{sup -6} cm{sup 2} s{sup -1} for the experimental conditions, using chronoamperometry.

  19. Cobalt oxide nanoparticle-modified carbon nanotubes as an ...

    Indian Academy of Sciences (India)

    Cobalt oxide nanoparticle-modified carbon nanotubes as an electrocatalysts for electrocatalytic evolution of oxygen gas ... activity of CoO–MWNT/GCE increased with the number of potential cycles employed for the CoO deposition till a certain loading (20 cycles) beyond which an adverse effect is observed.

  20. Modified structure of graphene oxide by investigation of structure ...

    Indian Academy of Sciences (India)

    erated in some regions due to hydrogen bonding between functional groups. Trapped water molecules were shown between the GO sheets which strongly affected the distribution of OFGs and their aggregation by hydrogen bonding. Keywords. Graphene oxide; oxygen functional groups; structure investigation; modified ...

  1. Cobalt oxide nanoparticle-modified carbon nanotubes as an ...

    Indian Academy of Sciences (India)

    of 60 mV were observed at. 100 mV s. −1 for CoOx−MWNT/GCE. An anodic peak at. 100 mV attributed to Co(II)/Co(III) redox transition associated with the electrode surface. The cathodic peak at 20 mV corre- spond to the reduction of various cobalt oxide species formed during the anodic sweep. The stability of the modified ...

  2. Super paramagnetic iron oxide nanoparticle modified mancozeb imprinted polymer

    Science.gov (United States)

    Kumar, Sunil; Madhuri, Rashmi; Sharma, Prashant K.

    2017-05-01

    An electrochemical sensor for detection of mancozeb from soil and vegetable sample using molecularly imprinted star polymer modified with iron oxide nanoparticles (SPIONs) is described in this work. We have prepared SPIONS by hydrothermal method and modified with vinyl silane to introduce double bond at their surface. The vinyl group modified SPIONs were used to form mancozeb imprinted star polymer (ISP). The ISPs have specific recognition ability high adsorption capacity towards their template molecule and could be easily extracted from complex matrices using a simple magnet. The prepared polymer was well characterized by field emissive scanning electron microscopy (FE-SEM). Under the optimum condition, the prepared sensor shows good response for mancozeb in the range of 5.96 to 222.39 µg L-1 (detection limit=0.98 µg L-1). The proposed sensors have highly selective for detection of mancozeb in soil and vegetable samples also.

  3. Evaluation of Aging Resistance of Graphene Oxide Modified Asphalt

    Directory of Open Access Journals (Sweden)

    Shaopeng Wu

    2017-07-01

    Full Text Available Graphene oxide (GO has a unique layered structure with excellent gas and liquid blocking properties. It is widely used in many areas, such as gas sensors, carbon-based electronics, impermeable membranes, and polymeric composite materials. In order to evaluate whether GO (1% and 3% by weight of asphalt can improve the aging resistance performance of the asphalt, 80/100 penetration grade asphalt (90 A and styrene–butadiene–styrene modified asphalt (SBS MA were used to prepare the GO modified asphalt by the melt blending method. The surface morphology of the GO was analyzed by scanning electron microscope (SEM. The UV aging test was conducted to simulate the aging during the service period. After UV aging test, the physical performances of GO-modified asphalts were tested, and the IC=O and IS=O increments were tested by Fourier transform infrared spectroscopy (FTIR to evaluate the aging resistance performance of the GO modified asphalt. In addition, the rheological properties of GO modified asphalts were studied using a dynamic shear rheometer (DSR. The SEM analysis indicated that the GO exhibits many shared edges, and no agglomeration phenomenon was found. With respect to the physical performance test, the FTIR and the DSR results show that GO can improve the UV aging resistance performance of 90 A and SBS MA. In addition, the analysis indicated that the improvement effect of 3% GO is better than the 1% GO. The testing on the rheological properties of the modified asphalt indicated that the GO can also improve the thermo-oxidative aging resistance performance of asphalt.

  4. Modified silver nanowire transparent electrodes with exceptional stability against oxidation

    International Nuclear Information System (INIS)

    Idier, J; Neri, W; Ly, I; Poulin, P; Backov, R; Labrugère, C

    2016-01-01

    We report an easy method to prepare thin, flexible and transparent electrodes that show enhanced inertness toward oxidation using modified silver nanowires (Ag NWs). Stabilization is achieved through the adsorption of triphenylphosphine (PPh 3 ) onto the Ag NW hybrid dispersions prior to their 2D organization as transparent electrodes on polyethylene terephtalate (PET) films. After 110 days in air (20 °C) under atmospheric conditions, the transmittance of the PET/Ag NW/PPh 3 based films is nearly unchanged, while the transmittance of the PET/Ag NW-based films decreases by about 5%. The sheet resistance increases for both materials as time elapses, but the rate of increase is more than four times slower for films stabilized by PPh 3 . The improved transmittance and conductivity results in a significantly enhanced stability for the figure of merit σ dc /σ op . This phenomenon is highlighted in highly oxidative nitric acid vapor. The tested stabilized films in such conditions exhibit a decrease to σ dc /σ op of only 38% after 75 min, whereas conventional materials exhibit a relative loss of 71%. In addition, by contrast to other classes of stabilizers, such as polymer or graphene-based encapsulants, PPh 3 does not alter the transparency or conductivity of the modified films. While the present films are made by membrane filtration, the stabilization method could be implemented directly in other liquid processes, including industrially scalable ones. (paper)

  5. Metal oxides modified NiO catalysts for oxidative dehydrogenation of ethane to ethylene

    KAUST Repository

    Zhu, Haibo

    2014-06-01

    The sol-gel method was applied to the synthesis of Zr, Ti, Mo, W, and V modified NiO based catalysts for the ethane oxidative dehydrogenation reaction. The synthesized catalysts were characterized by XRD, N2 adsorption, SEM and TPR techniques. The results showed that the doping metals could be highly dispersed into NiO domains without the formation of large amount of other bulk metal oxide. The modified NiO materials have small particle size, larger surface area, and higher reduction temperature in contrast to pure NiO. The introduction of group IV, V and VI transition metals into NiO decreases the catalytic activity in ethane ODH. However, the ethylene selectivity is enhanced with the highest level for the Ni-W-O and Ni-Ti-O catalysts. As a result, these two catalysts show improved efficiency of ethylene production in the ethane ODH reaction. © 2014 Elsevier B.V. All rights reserved.

  6. Oxidatively Modified Proteins in the Serous Subtype of Ovarian Carcinoma

    Directory of Open Access Journals (Sweden)

    Sharifeh Mehrabi

    2014-01-01

    Full Text Available Serous subtype of ovarian cancer is considered to originate from fallopian epithelium mucosa that has been exposed to physiological changes resulting from ovulation. Ovulation influences an increased in inflammation of epithelial ovarian cells as results of constant exposure of cells to ROS. The imbalance between ROS and antioxidant capacities, as well as a disruption of redox signaling, causes a wide range of damage to DNA, proteins, and lipids. This study applied spectrophotometric, dinitrophenylhydrazone (DNPH assay, two-dimensional gel electrophoresis, and Western blot analyses to assess the levels of oxidatively modified proteins in 100 primary serous epithelial ovarian carcinoma and normal/surrounding tissues. These samples were obtained from 56 Caucasian and 44 African-American patients within the age range of 61±10 years. Analyses showed that the levels of reactive protein carbonyl groups increased as stages progressed to malignancy. Additionally, the levels of protein carbonyls in serous ovarian carcinoma among African Americans are 40% (P<0.05 higher relative to Caucasian at similar advanced stages. Results suggest that oxidative stress is involved in the modification of carbonyl protein groups, leading to increased aggressiveness of epithelial ovarian tumors and may contribute to the disease's invasiveness among African Americans.

  7. Enhanced transparent conducting networks on plastic substrates modified with highly oxidized graphene oxide nanosheets

    Science.gov (United States)

    Woo, Jong Seok; Sin, Dong Hun; Kim, Haena; Jang, Jeong In; Kim, Ho Young; Lee, Geon-Woong; Cho, Kilwon; Park, Soo-Young; Han, Joong Tark

    2016-03-01

    Atomically thin and two-dimensional graphene oxide (GO) is a very fascinating material because of its functional groups, high transparency, and solution processability. Here we show that highly oxidized GO (HOGO) nanosheets serve as an effective interfacial modifier of transparent conducting films with one-dimensional (1D) silver nanowires (AgNWs) and single-walled carbon nanotubes (SWCNTs). Optically transparent and small-sized GO nanosheets, with minimal sp2 domains, were successfully fabricated by step-wise oxidation and exfoliation of graphite. We demonstrated that under-coated HOGO further decreases the sheet resistance of the SWCNT film top-coated with HOGO by increasing the contact area between the SWCNTs and HOGO nanosheets by generating hole carriers in the SWCNT as a result of charge transfer. Moreover, HOGO nanosheets with AgNWs contribute to the efficient thermal joining of AgNW networks on plastic substrates by limiting the thermal embedding of AgNWs into the plastic surface, resulting in efficient decrease of the sheet resistance. Furthermore, flexible organic photovoltaic cells with GO-modified AgNW anodes on a flexible substrate were successfully demonstrated.Atomically thin and two-dimensional graphene oxide (GO) is a very fascinating material because of its functional groups, high transparency, and solution processability. Here we show that highly oxidized GO (HOGO) nanosheets serve as an effective interfacial modifier of transparent conducting films with one-dimensional (1D) silver nanowires (AgNWs) and single-walled carbon nanotubes (SWCNTs). Optically transparent and small-sized GO nanosheets, with minimal sp2 domains, were successfully fabricated by step-wise oxidation and exfoliation of graphite. We demonstrated that under-coated HOGO further decreases the sheet resistance of the SWCNT film top-coated with HOGO by increasing the contact area between the SWCNTs and HOGO nanosheets by generating hole carriers in the SWCNT as a result of charge

  8. Radiation Stability of Zinc Oxide Pigment Modified by Zirconium Oxide and Aluminum Oxide Nanopowders

    International Nuclear Information System (INIS)

    Mikhailov, M. M.; Neshchimenko, V. V.; Li Chundong

    2009-01-01

    The effect on the reflective spectra of heat treatment and modification of ZnO pigments by 1-30 wt.%ZrO 2 and Al 2 O 3 nanoparticles has been investigated before and after irradiation by 100 keV protons with a fluence of 5x10 15 cm -2 . It is established that with the optimum concentration of 5 wt.% nanoparticles and the temperature of 800 deg. C a 20% increase in the radiation stability is observed for the modified ZnO pigment in comparison with the not modified pigment. The decrease of absorption in the modified pigments is determined by the decrease of the intensity of the absorption bands of the zinc vacancies (V zn - ), oxygen vacancies (V o + ) and donor-acceptor couples (V zn - - Zn i 0 ).

  9. The emulsifying and tribological properties of modified graphene oxide in oil-in-water emulsion

    NARCIS (Netherlands)

    Wu, Yinglei; Zeng, Xiangqiong; Ren, Tianhui; de Vries, Erik G.; van der Heide, Emile

    2017-01-01

    Graphene oxide (GO) was asymmetric chemically modified with myristyltrimethylammonium bromide (TTAB) to get modified graphene oxide (MGO). This MGO was used as an emulsifier and additive in oil-in-water emulsion. The emulsifying tests showed MGO greatly improved the stability of base emulsion and

  10. investigation of the effect of zinc oxide-modified gum arabic on polar ...

    African Journals Online (AJOL)

    BARTH EKWUEME

    Gum Arabic solution, a water-based adhesive, was modified with zinc oxide filler and the formulation was ... starch and dextrin, polyvinyl alcohol, cellulose nitrate, .... Zinc oxide-modified gum Arabic improved bond strength on ceramic due to dipole-dipole interactions as well as electrovalent bonds formed between gum ...

  11. Application of Ferriferous Oxide Modified by Chitosan in Gene Delivery

    Directory of Open Access Journals (Sweden)

    Yu Kuang

    2012-01-01

    Full Text Available New approaches to improve the traditional gene carriers are still required. Here we explore Fe3O4 modified with degradable polymers that enhances gene delivery and target delivery using permanent magnetic field. Two magnetic Fe3O4 nanoparticles coated with chitosan (CTS and polyethylene glycol (PEG were synthesized by means of controlled chemical coprecipitation. Plasmid pEGFP was encapsulated as a reported gene. The ferriferous oxide complexes were approximately spherical; surface charge of CTS-Fe3O4 and PEG-Fe3O4 was about 20 mv and 0 mv, respectively. The controlled release of DNA from the CTS-Fe3O4 nanoparticles was observed. Concurrently, a desired Fe3O4 concentration of less than 2 mM was verified as safe by means of a cytotoxicity test in vitro. Presence of the permanent magnetic field significantly increased the transfection efficiency. Furthermore, the passive target property and safety of magnetic nanoparticles were also demonstrated in an in vivo test. The novel gene delivery system was proved to be an effective tool required for future target expression and gene therapy in vivo.

  12. Surface-modified low-temperature solid oxide fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Young Beom; Holme, Timothy P. [Department of Mechanical Engineering, Stanford University, Stanford, CA 94305 (United States); Guer, Turgut M. [Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305 (United States); Prinz, Fritz B. [Department of Mechanical Engineering, Stanford University, Stanford, CA 94305 (United States); Department of Materials Science and Engineering, Stanford University, Stanford, CA 94305 (United States)

    2011-12-20

    This paper reports both experimental and theoretical results of the role of surface modification on the oxygen reduction reaction in low-temperature solid oxide fuel cells (LT-SOFC). Epitaxial ultrathin films of yttria-doped ceria (YDC) cathode interlayers (<10-130 nm) are grown by pulsed laser deposition (PLD) on single-crystalline YSZ(100). Fuel cell current-voltage measurements and electrochemical impedance spectroscopy are performed in the temperature range of 350 C {approx} 450 C. Quantum mechanical simulations of oxygen incorporation energetics support the experimental results and indicate a low activation energy of only 0.07 eV for YDC, while the incorporation reaction on YSZ is activated by a significantly higher energy barrier of 0.38 eV. Due to enhanced oxygen incorporation at the modified Pt/YDC interface, the cathodic interface resistance is reduced by two-fold, while fuel cell performance shows more than a two-fold enhancement with the addition of an ultrathin YDC interlayer at the cathode side of an SOFC element. The results of this study open up opportunities for improving cell performance, particularly of LT-SOFCs by adopting surface modification of YSZ surface with catalytically superior, ultrathin cathodic interlayers. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Emulsifying Property and Antioxidative Activity of Cuttlefish Skin Gelatin Modified with Oxidized Linoleic Acid and Oxidized Tannic Acid

    NARCIS (Netherlands)

    Aewsiri, T.; Benjakul, S.; Visessanguan, W.; Wierenga, P.A.; Gruppen, H.

    2013-01-01

    Cuttlefish skin gelatins modified with oxidized linoleic acid (OLA) and oxidized tannic acid (OTA) were characterized and determined for emulsifying properties and antioxidative activity. Modification of gelatin with 5% OTA increased the total phenolic content and 1,1-diphenyl-2-picrylhydrazyl,

  14. Self-consistent-field analysis of the micellization of carboxy-modified poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymers

    NARCIS (Netherlands)

    Lauw, Y.; Leermakers, F.A.M.; Cohen Stuart, M.A.

    2006-01-01

    The micellization properties of carboxy-modified Pluronics P85 (poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymers) are investigated by means of a molecularly realistic self-consistent-field theory. We consider the, so-called, carboxylic acid

  15. Solvent-Free Selective Oxidation of Toluene with O2 Catalyzed by Metal Cation Modified LDHs and Mixed Oxides

    Directory of Open Access Journals (Sweden)

    Xiaoli Wang

    2016-01-01

    Full Text Available A series of metal cation modified layered-double hydroxides (LDHs and mixed oxides were prepared and used to be the selective oxidation of toluene with O2. The results revealed that the modified LDHs exhibited much higher catalytic performance than their parent LDH and the modified mixed oxides. Moreover, the metal cations were also found to play important roles in the catalytic performance and stabilities of modified catalysts. Under the optimal reaction conditions, the highest toluene conversion reached 8.7% with 97.5% of the selectivity to benzyldehyde; moreover, the catalytic performance remained after nine catalytic runs. In addition, the reaction probably involved a free-radical mechanism.

  16. Modified lithium vanadium oxide electrode materials products and methods

    Science.gov (United States)

    Thackeray, Michael M.; Kahaian, Arthur J.; Visser, Donald R.; Dees, Dennis W.; Benedek, Roy

    1999-12-21

    A method of improving certain vanadium oxide formulations is presented. The method concerns fluorine doping formulations having a nominal formula of LiV.sub.3 O.sub.8. Preferred average formulations are provided wherein the average oxidation state of the vanadium is at least 4.6. Herein preferred fluorine doped vanadium oxide materials, electrodes using such materials, and batteries including at least one electrode therein comprising such materials are provided.

  17. Modified calcium oxide as stable solid base catalyst for Aldol ...

    Indian Academy of Sciences (India)

    The influence of several reaction parameters, such as temperature, catalyst loading, was investigated. The humidity test over modified CaO reveals that the basic centres of modified CaO are stable for CO2 and moisture. From the results of Fourier transform-infrared (FT-IR) and Thermogravity analysis (TG) characterization, ...

  18. Modified calcium oxide as stable solid base catalyst for Aldol ...

    Indian Academy of Sciences (India)

    A highly efficient and stable solid-base catalyst for Aldol condensation was prepared by modifying commercial CaO with benzyl bromide in a simple way. It was found that modified CaO can effectively catalyse the Aldol condensation of cyclohexanone and benzaldehyde, as well as various benzaldehydes, to produce ...

  19. Modified structure of graphene oxide by investigation of structure ...

    Indian Academy of Sciences (India)

    The structure of graphite oxide and graphene oxide (GO) has been studied previously using various analyses and computer simulations. Although some oxygen functional groups (OFGs) are accepted as the main functionalities in GO, the structure of GO has remained elusive. In this regard, GO was produced using the ...

  20. Polymer derived non-oxide ceramics modified with late transition metals.

    Science.gov (United States)

    Zaheer, Muhammad; Schmalz, Thomas; Motz, Günter; Kempe, Rhett

    2012-08-07

    This tutorial review highlights the methods for the preparation of metal modified precursor derived ceramics (PDCs) and concentrates on the rare non-oxide systems enhanced with late transition metals. In addition to the main synthetic strategies for modified SiC and SiCN ceramics, an overview of the morphologies, structures and compositions of both, ceramic materials and metal (nano) particles, is presented. Potential magnetic and catalytic applications have been discussed for the so manufactured metal containing non-oxide ceramics.

  1. Photocatalytic oxidation of VOC, nitrogen oxide and atrazine using titanium dioxide modified with perovskite materials

    Science.gov (United States)

    Vajifdar, Kayzad Jimmy

    to meet the EPA's ever tightening emission standards and will give architects and town planners a new weapon in the fight against pollution in the foreseeable future. This chapter also shows the visible-light excited photocatalytic oxidation of NOx at different inlet NO concentration, space time, and relative humidity. The reaction products are studied with a NOx analyzer and ion chromatography from gas phase, catalyst and scrubber liquor. A possible mechanism is proposed. The oxidation products are NO 2, HNO2, and HNO3. The former can be captured in an adsorbent bed and recovered as nitric acid. Chapter 3 investigates the photocatalytic oxidation (PCO) of atrazine in aqueous solution under 9 W fluorescent light irradiation using four different types of photocatalysts: Degussa P-25 standard TiO2, Ecodevice BA-PW25, Nd-doped TiO2 prepared by sol-gel technique and TiO 2 modified with BaTiO3. With an initial atrazine concentration of 60 ppb, after PCO only two products remain in detectable levels. Up to 77% of decomposed atrazine becomes hydroxyatrazine, the major byproduct; the second product peak remains undefined. Both atrazine and hydroxyatrazine photodecompose following the first order rate equation, but the hydroxyatrazine photodecomposition rate is significantly slower than that of atrazine. Doping TiO2 with Nd+3/Ba+2 reduces the photodegradation time. The difference in the ionic radii of Ba+2 and Nd +3 as compared to Ti+4, and the oxygen affinities of Ba and Nd as compared to Ti are responsible for this effect. These differences help to promote electron trapping, thereby increasing the lifetime of the holes that are responsible for the oxidation of atrazine.

  2. Modifying ferritic stainless steels for solid oxide fuel cell applications

    Science.gov (United States)

    Laney, Scot Jason

    2007-12-01

    One of the most important problem areas associated with the solid oxide fuel cells is selection of a cost effective material for use as the interconnect component of the cell. Metals are now being considered as materials for this component, with ferritic stainless steels being the leading candidate. This work evaluates methods to combat the problem areas, namely rapid growth rate and vaporization of the oxide scale, that hinder the use of these materials. Oxidation experiments have been performed in dry and wet single atmosphere exposures as well as a dual environment exposure to simulate the conditions in a working SOFC. Measurements of the electrical properties of the oxides that formed were also performed. Commercial alloys, E-Brite and Crofer 22APU, were tested to form a baseline and resultant oxidation and electrical behaviors match those found in the literature. Isothermal oxidation tests for short exposure times have also led to a possible mechanism for the formation of the MnCr2O4 layer on Crofer. All of these tests were then replicated on a series of experimental Fe-22Cr-XTi (X=0-4) alloys. These alloys are shown to form a rutile layer analogous to the MnCr2O4 layer on Crofer. While this layer does prevent some chromia vaporization, the consequences due to the presence of Ti in the chromia include increased growth rate, decreased resistivity, extensive internal oxidation and nitridation of Ti, and a change of the growth direction of the chromia. The alloys containing ˜2--3 wt%Ti appear to offer the best combination of oxidation, electrical, and mechanical properties. Coatings of lanthanum chromites and ferrites were also tested and shown to be very sensitive to exposure condition, resulting in the formation of pores, and to coating thickness, where thicker coatings are subject to cracking. Finally, reactive element oxide doping was attempted to slow the oxide growth rate for E-Brite (CeO2 doping) and for the Fe-Cr-Ti alloys (CeO 2 and La2O3 doping). A

  3. Investigation of the effect of zinc oxide-modified gum Arabic on polar ...

    African Journals Online (AJOL)

    Gum Arabic solution, a water-based adhesive, was modified with zinc oxide filler and the formulation was applied on wood, ceramic, glass and textile substrates. A strip of paper was used as a common adherent to all the substrates. Zinc oxide increased the viscosity of 30wt% gum Arabic solution and increased bond ...

  4. Silicone-modified graphene oxide fillers via the Piers-Rubinsztajn reaction

    DEFF Research Database (Denmark)

    Zhang, Jianfeng; Liang, Shuai; Yu, Liyun

    2016-01-01

    While graphene or graphene oxide can make significantimprovements in the properties of a wide variety of polymericmaterials, their incorporation can be challenged byincompatibility with the polymeric matrix. The modification ofgraphene oxide with silicones or silanes using the Piers......-Rubinsztajn reaction improves dispersibility in nonpolar materials,including organic solvents and silicone pre-elastomers. Ahigh loading (up to 10 wt %) of modified graphene oxide insilicone elastomers could be achieved, which resulted inenhanced mechanical performance and reduced gas permeability....

  5. Efficient inverted polymer solar cells based on conjugated polyelectrolyte and zinc oxide modified ITO electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Tao; Zhu, Xiaoguang; Tu, Guoli, E-mail: tgl@hust.edu.cn [Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074 (China); Zhou, Lingyu [State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian National Laboratory of Clean Energy, Dalian 116023 (China); Zhang, Jian, E-mail: jianzhang@guet.edu.cn [Department of Material Science and Engineering, Guangxi Key Laboratory of Information Materials, Guilin University of Electronic Technology, Guilin 541004 (China)

    2015-02-23

    Efficient inverted polymer solar cells (PSCs) were constructed by utilizing a conjugated polyelectrolyte PF{sub EO}SO{sub 3}Na and zinc oxide to modify the indium tin oxide (ITO) electrode. The ITO electrode modified by PF{sub EO}SO{sub 3}Na and zinc oxide possesses high transparency, increased electron mobility, smoothened surface, and lower work function. PTB7:PC{sub 71}BM inverted PSCs containing the modified ITO electrode achieved a high power conversion efficiency (PCE) of 8.49%, exceeding that of the control device containing a ZnO modified ITO electrode (7.48%). Especially, PCE-10:PC{sub 71}BM inverted polymer solar cells achieved a high PCE up to 9.4%. These results demonstrate a useful approach to improve the performance of inverted polymer solar cells.

  6. Phosphate adsorption using modified iron oxide-based sorbents

    Science.gov (United States)

    Phosphate RemovalThis dataset is associated with the following publication:Lalley , J., C. Han , G. RamMohan , T. Speth , J. Garland , M. Nadagouda , and D. Dionysiou. Phosphate Removal using Modified Bayoxide®E33 Adsorption Media. WATER RESEARCH. Elsevier Science Ltd, New York, NY, USA, issue}: 96-107, (2015).

  7. Modified calcium oxide as stable solid base catalyst for Aldol ...

    Indian Academy of Sciences (India)

    rated and washed with methanol to remove excess modi- fier, and the modified CaO was obtained after a vacuum drying process. In order to increase the reproducibili- ty, the particles were sieved before use. Particles of. 100–160 mesh size were selected for all experiments. 2.2 Humidity test. Amount of commercial CaO ...

  8. Cobalt oxide nanoparticle-modified carbon nanotubes as an ...

    Indian Academy of Sciences (India)

    Mazandaran University, Babolsar, Iran. 2Ayatollah Amoli Branch, Department of Chemistry, Islamic Azad University, PO Box 678, Amol, Iran. MS received 13 September 2013; revised 18 .... Figure 3 shows a cyclic voltammograms of the modified elec- trodes in 0.5 M KOH solution in the potential window of. −100 to 400 mV ...

  9. Graphene oxide layers modified by light energetic ions

    Czech Academy of Sciences Publication Activity Database

    Malinský, Petr; Macková, Anna; Mikšová, Romana; Kováčiková, Helena; Cutroneo, Mariapompea; Luxa, J.; Bouša, D.; Štrochová, B.; Sofer, Z.

    2017-01-01

    Roč. 19, č. 16 (2017), s. 10282-10291 ISSN 1463-9076 R&D Projects: GA ČR GA16-05167S; GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : graphene oxide * reduction * irradiation Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nuclear physics Impact factor: 4.123, year: 2016

  10. Measurement and meaning of oxidatively modified DNA lesions in urine

    DEFF Research Database (Denmark)

    Cooke, Marcus S; Olinski, Ryszard; Loft, Steffen

    2008-01-01

    G levels and is not sufficiently specific for accurate quantification. With increasing numbers of lesions being studied, it is vital that these fundamental issues are addressed. We report the formation of the European Standards Committee on Urinary (DNA) Lesion Analysis whose primary goal is to achieve......BACKGROUND: Oxidatively generated damage to DNA has been implicated in the pathogenesis of a wide variety of diseases. The noninvasive assessment of such damage, i.e., in urine, and application to large-scale human studies are vital to understanding this role and devising intervention strategies....... METHODS: We have reviewed the literature to establish the status quo with regard to the methods and meaning of measuring DNA oxidation products in urine. RESULTS: Most of the literature focus upon 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), and whereas a large number of these reports concern clinical...

  11. Formation of TiO/Al2O3/C Composite in Thermal Co-decomposition of Aluminium(III) Acetylacetonate and Titanium(IV) Oxyacetylacetonate.

    Czech Academy of Sciences Publication Activity Database

    Kovářík, T.; Pokorná, Dana; Urbanová, Markéta; Bezdička, Petr; Bastl, Zdeněk; Kupčík, Jaroslav; Křenek, T.; Pola, M.; Kullová, L.; Pola, Josef

    2016-01-01

    Roč. 117, JAN 2016 (2016), s. 182-190 ISSN 0165-2370 R&D Projects: GA TA ČR TA04020860 Institutional support: RVO:67985858 ; RVO:61388980 ; RVO:61388955 Keywords : thermal co-decomposition * aluminium(III) acetylacetonate * titanium(IV) oxyacetylacetonate * titanium monoxide * alumina * Carbona Subject RIV: CF - Physical ; Theoretical Chemistry; CA - Inorganic Chemistry (UACH-T) Impact factor: 3.471, year: 2016

  12. Modifying zirconia solid electrolyte surface property to enhance oxide transport

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, B.Y.; Song, S.Y. [Univ. of Hawaii, Honolulu, HI (United States)

    1996-12-31

    Bismuth-strontium-calcium-copper oxide (Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}, BSCCO) is known for its high T{sub c} superconducting behavior and mixed conducting property. The applicability of similar high T{sub c} cuprates for intermediate-temperature solid oxide fuel cell (SOFC) application has been studied recently. We investigated the electrochemical behavior of several Ag{vert_bar}BSCCO{vert_bar}10 mol% yttria-stabilized zirconia (YSZ){vert_bar}Ag and Ag{vert_bar}YSZ{vert_bar}Ag cells using complex impedance spectroscopy. A highly uniform and porous microstructure was observed at the interface of the YSZ and BSCCO. The ionic conductivity determined from the Nyquest plots in the temperature range of 200-700{degrees}C agrees with the values reported in the literature. The specific resistance of the BSCCO{vert_bar}YSZ interface was also determined to be lower than those of the conventional manganite electrode, suggesting that BSCCO seems attractive for cathode applications in SOFC.

  13. Humidity Sensing Properties of Surface Modified Polyaniline Metal Oxide Composites

    Directory of Open Access Journals (Sweden)

    S. C. Nagaraju

    2014-01-01

    Full Text Available Polyaniline- (PANI praseodymium Oxide (Pr2O3 composites have been synthesized by in situ polymerization method with different weight percentages. The synthesized composites have been characterized by Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy. The temperature dependent conductivity shows that the conductivity is due to the hopping of polarons and bipolarons. These composites show negative thermal coefficient (α behavior as a function of temperature, which is characteristic behavior of semiconducting materials. Sensor studies have been carried out by two-probe method and found that the sensitivity increases with increase in % RH. It is noticed that stability increase is due to the presence of Pr2O3 in polyaniline up to 30 wt%. A fast recovery and response time along with high sensitivity make these composites suitable for humidity sensors.

  14. Oxide nano particles modified by 2-benzothiazolylthiosuccinic acid

    International Nuclear Information System (INIS)

    Dang Quyet Thang; Trinh Anh Truc; Pham Gia Vu; To Thi Xuan Hang

    2015-01-01

    In this study, ZnO nanoparticle was synthesized and modified by a corrosion inhibitor 2-benzothiazolylthiosuccinic acid (BTSA) for corrosion protection of a carbon steel surface. The TEM, SEM and IR analyses were used for characterized the synthesized products. The nano ZnO size in the about 20 nm and the IR analyze shows the presence of BTSA on the ZnO surface. The corrosion inhibition of nano ZnO and nano ZnO bearing BTSA in the NaCL 0.1 M solution was characterized using electrochemical techniques. In the NaCl 0.1 M, both nano ZnO and nano ZnO-BTSA have the inhibition property for carbon steel surface. The inhibition efficiency of ZnO-BTSA in higher than of pure ZnO. The polarization curves indicate that ZnO is anodic inhibitor while the ZnO-BTSA is a mixed-type inhibitor. (author)

  15. Electrochemical oxidation of ascorbic acid mediated by carbon nano tubes/ Li+/ carbon paste modified solid electrode

    International Nuclear Information System (INIS)

    Goh, J.K.; Tan, W.T.

    2008-01-01

    Multi-walled carbon nano tube (MWCNT) was used to modify BPPG electrode because of its unique structure and extraordinary properties. MWCNT modified electrode exhibited obvious enhancing and electro catalyzing effects to the oxidation of ascorbic acid using cyclic voltammetry technique. MWCNT was bonded on BPPG electrode surface using carbon paste with ratio of 30 % (w/ W) carbon paste (binder): 70 % (w/ w) MWCNT. This method of modification has lowered the capacitance background current and enabled lower detection limit of ascorbic acid concentration. The electrical conductivity property of MWCNT modified electrode was further improved with the intercalation with lithium ion and resulted in current enhancement of 2 times on the oxidation current of ascorbic acid. Parameters of pH and temperature showed significant relation to the sensitivity of MWCNT modified electrode. Under the optimized parameters, the calibration curve constructed was linear up from 50 μM to 5 mM with sensitivity of 34.5 mA M -1 . The practical application of MWCNT modified electrode was demonstrated with Vitamin C pill and orange juice. Good reproducibility and recovery of ascorbic acid concentration showed the feasibility of MWCNT modified electrode to be used in the detection of ascorbic acid in aqueous solution. This also proposed MWCNT modified BPPG electrode possessed advantages such as low detection limit, high stability, low cost and simplicity in fabrication. (author)

  16. Modified tricalcium silicate cement formulations with added zirconium oxide.

    Science.gov (United States)

    Li, Xin; Yoshihara, Kumiko; De Munck, Jan; Cokic, Stevan; Pongprueksa, Pong; Putzeys, Eveline; Pedano, Mariano; Chen, Zhi; Van Landuyt, Kirsten; Van Meerbeek, Bart

    2017-04-01

    This study aims to investigate the effect of modifying tricalcium silicate (TCS) cements on three key properties by adding ZrO 2 . TCS powders were prepared by adding ZrO 2 at six different concentrations. The powders were mixed with 1 M CaCl 2 solution at a 3:1 weight ratio. Biodentine (contains 5 wt.% ZrO 2 ) served as control. To evaluate the potential effect on mechanical properties, the mini-fracture toughness (mini-FT) was measured. Regarding bioactivity, Ca release was assessed using ICP-AES. The component distribution within the cement matrix was evaluated by Feg-SEM/EPMA. Cytotoxicity was assessed using an XTT assay. Adding ZrO 2 to TCS did not alter the mini-FT (p = 0.52), which remained in range of that of Biodentine (p = 0.31). Ca release from TSC cements was slightly lower than that from Biodentine at 1 day (p > 0.05). After 1 week, Ca release from TCS 30 and TCS 50 increased to a level that was significantly higher than that from Biodentine (p  0.05). EPMA revealed a more even distribution of ZrO 2 within the TCS cements. Particles with an un-reacted core were surrounded by a hydration zone. The 24-, 48-, and 72-h extracts of TCS 50 were the least cytotoxic. ZrO 2 can be added to TCS without affecting the mini-FT; Ca release was reduced initially, to reach a prolonged release thereafter; adding ZrO 2 made TCS cements more biocompatible. TCS 50 is a promising cement formulation to serve as a biocompatible hydraulic calcium silicate cement.

  17. Investigation of thermal oxidative break-down of polyethylene films modified with grafted polyacrylonitrile

    International Nuclear Information System (INIS)

    Krul', L.P.; Gert, E.V.

    1981-01-01

    Thermal oxidative destruction of polyethylene (PE) films modified by radiation (#betta#-radiation, dose rate is 0.56 Mrad/hr) liquid-phase graft polymerization of acrylonitrile (AN) has been studied. Comparative stability of grafted copolymers, homopolymers and mechanical mixtures of PE and PAN (polyacrylonitrile) to thermal oxidative destruction is studied using the derivatographic method. It is shown that graft of PAN considerably decelerates the development of oxidative and destructive processes in PE, at that, the efficiency of PE chain stabilization increases with the increase of grafted PAN amount. The sample with PAN content x=0.367 (in parts of the mass of grafted film) possesses the highest stability

  18. Platelet deposition studies on copolyether urethanes modified with poly(ethylene oxide)

    NARCIS (Netherlands)

    Brinkman, E.; Foot, A.; van der Does, L.; Bantjes, A.

    1990-01-01

    Pellethane ® 2363 80A films and tubings were chemically modified and the effect of these modifications on platelet deposition was studied. Grafting of high molecular weight poly(ethylene oxide) and graft polymerization of methoxy poly(ethylene glycol) 400 methacrylate resulted in surfaces with a

  19. Rapid determination of iron oxide content in magnetically modified particulate materials

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Nýdlová, L.; Pospíšková, K.; Baldíková, E.; Maděrová, Z.; Šafaříková, Miroslava

    2016-01-01

    Roč. 26, June (2016), s. 114-117 ISSN 1674-2001 Institutional support: RVO:60077344 Keywords : magnetic iron oxides * magnetic permeability meter * magnetically modified materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.621, year: 2016

  20. Effect of citric acid on formation of oxides of Cu and Zn in modified ...

    Indian Academy of Sciences (India)

    Effect of citric acid on formation of oxides of Cu and Zn in modified sol-gel process: A comparative study. KAMARAJ MAHENDRAPRABHU and PERUMAL ELUMALAI. ∗. Electrochemical Energy and Sensors Lab, Department of Green Energy Technology,. Madanjeet School of Green Energy Technologies, Pondicherry ...

  1. Schizophrenia and oxidative stress: glutamate cysteine ligase modifier as a susceptibility gene

    DEFF Research Database (Denmark)

    Tosic, Mirjana; Ott, Jurg; Barral, Sandra

    2006-01-01

    Oxidative stress could be involved in the pathophysiology of schizophrenia, a major psychiatric disorder. Glutathione (GSH), a redox regulator, is decreased in patients' cerebrospinal fluid and prefrontal cortex. The gene of the key GSH-synthesizing enzyme, glutamate cysteine ligase modifier (GCLM...

  2. Surface activity and molecular characteristics of cuttlefish skin gelatin modified by oxidized linoleic acid

    NARCIS (Netherlands)

    Aewsiri, T.; Benjakul, S.; Visessanguan, W.; Wierenga, P.A.; Gruppen, H.

    2011-01-01

    Surface activity and molecular changes of cuttlefish skin gelatin modified with oxidized linoleic acid (OLA) prepared at 60, 70 and 80 °C at different times were investigated. Modification of gelatin with OLA could improve surface activity of resulting gelatin as evidenced by the decreased surface

  3. Modified Poisson solver for the simulation of the silicon-oxide interface in semiconductor detectors

    Energy Technology Data Exchange (ETDEWEB)

    Castoldi, A. E-mail: andrea.castoldi@polimi.it; Rehak, P.; Gatti, E.; Guazzoni, C.; De Geronimo, G

    2000-01-11

    We present a modified Poisson solver for depleted semiconductor detectors that takes into account the effects of possible accumulation of mobile charge at the silicon-oxide interfaces. The solver is based on a physical model that closely approximates the correct boundary condition at the silicon-oxide interface. The model assumes that the silicon-oxide interface is divided into an equipotential region, where the electron layer is located, and a fully depleted region. The actual extension and potential of the electron layer region are approximated with the desired accuracy by an iterative procedure. This model has been implemented in 2- and 3-D Poisson solvers. The comparison with a 2-D drift-diffusion simulator has shown the accuracy of the proposed method. The modified Poisson solver has shown to be useful in giving accurate solutions to 3-D design problems at high CPU speed.

  4. Modified Poisson solver for the simulation of the silicon-oxide interface in semiconductor detectors

    CERN Document Server

    Castoldi, A; Gatti, E; Guazzoni, C; De Geronimo, G

    2000-01-01

    We present a modified Poisson solver for depleted semiconductor detectors that takes into account the effects of possible accumulation of mobile charge at the silicon-oxide interfaces. The solver is based on a physical model that closely approximates the correct boundary condition at the silicon-oxide interface. The model assumes that the silicon-oxide interface is divided into an equipotential region, where the electron layer is located, and a fully depleted region. The actual extension and potential of the electron layer region are approximated with the desired accuracy by an iterative procedure. This model has been implemented in 2- and 3-D Poisson solvers. The comparison with a 2-D drift-diffusion simulator has shown the accuracy of the proposed method. The modified Poisson solver has shown to be useful in giving accurate solutions to 3-D design problems at high CPU speed.

  5. Preparation and characterization of sugar cane bagasse fiber modified with nanoparticles of zirconium oxide

    International Nuclear Information System (INIS)

    Carvalho, K.C.C. de; Mulinari, D.R.; Voorwald, H.C.J.; Cioffi, M.O.H.

    2010-01-01

    The sugar cane bagasse fiber are renewable materials and have great application potential when used as reinforcement in a polymer matrix to give rise to composite materials and as supports for adsorption of heavy metals. This paper therefore describes the preparation and characterization of bleached and hydrated zirconium oxide modified sugar cane bagasse fiber by conventional precipitation method. Through the technique of electron microscopy we observed the presence of oxide nanoparticles on the fiber surface, proving the efficiency of the conventional precipitation method. With the X-ray diffraction analysis it was determined a decrease of 6.2% in the crystallinity index of modified fibers when compared to the bleached fibers showing the deposition of amorphous zirconium oxide on the fiber surface. (author)

  6. Catalytic oxidation of cyanides in an aqueous phase over individual and manganese-modified cobalt oxide systems

    International Nuclear Information System (INIS)

    Christoskova, St.; Stoyanova, M.

    2009-01-01

    The possibility for purification of wastewaters containing free cyanides by applying of a new method based on cyanides catalytic oxidation with air to CO 2 and N 2 at low temperature and atmospheric pressure was investigated. On this purpose, individual and modified with manganese Co-oxide systems as active phase of environmental catalysts were synthesized. The applied method of synthesis favours the preparation of oxide catalytic systems with high active oxygen content (total-O* and surface-O* s ) possessing high mobility, and the metal ions being in a high oxidation state and in an octahedral coordination-factors determining high activity in reactions of complete oxidation. The catalysts employed were characterized by powder X-ray diffraction, Infrared spectroscopy, and chemical analysis. The effect of pH of the medium and catalyst loading on the effectiveness of the cyanide oxidation process, expressed by the degree of conversion (α, %), by the rate constant (k, min -1 ), and COD was studied. The results obtained reveal that using catalysts investigated a high cyanide removal efficiency could be achieved even in strong alkaline medium. The higher activity of the manganese promoted catalytic sample could be explained on the basis of higher total active oxygen content and its higher mobility both depending on the conditions, under which the synthesis of catalyst is being carried out.

  7. Evaluation of Thermal Oxidative Aging Effect on the Rheological Performance of Modified Asphalt Binders

    Science.gov (United States)

    Zhu, Cheng

    Modified asphalt binder, which is combined by base binder and additive modifier, has been implemented in pavement industry for more than 30 years. Recently, the oxidative aging mechanism of asphalt binder has been studied for several decades, and appreciable finding results of asphalt binder aging mechanism were achieved from the chemistry and rheological performance aspects. However, most of these studies were conducted with neat binders, the research of aging mechanism of modified asphalt binder was limited. Nowadays, it is still highly necessary to clarify how the asphalt binder aging happens with the modified asphalt binder, what is the effect of the different modifiers (additives) on the binder aging process, how the rheological performance changes under the thermal oxidative aging conditions and so on. The objective of this study was to investigate the effect of isothermal oxidative aging conditions on the rheological performance change of the modified and controlled asphalt binders. There were totally 14 different sorts of asphalt binders had been aged in the PAV pans in the air-force drafted ovens at 50°C, 60°C and 85°C for 0.5 day to 240 days. The Fourier-Transform Infrared Spectroscopy (FT-IR) and Dynamic Shear Rheometer (DSR) were used to perform the experiments. The analysis of rheological indices (Low shear viscosity-LSV, Crossover modulus-G*c, Glover-Rowe Parameter-G-R, DSR function-DSR Fn) as a function of carbonyl area (CA) was conducted. With the SBS modification, both of the hardening susceptibility of the rheological index-LSV and G-R decreases compared with the corresponding base binder. The TR increased the hardening susceptibility of all the rheological indexes. While for the G*c, SBS increases the slope of the most modified asphalt binders except A and B_TR_X series binders. The multiple linear regression statistical analysis results indicate that the oxidative aging conditions play an important role on the CA, and rheological performance

  8. The Wear behavior of UHMWPE against Surface Modified CP-Titanium by Thermal Oxidation

    Directory of Open Access Journals (Sweden)

    B.T. Prayoga

    2016-12-01

    Full Text Available The effects of thermal oxidation duration on hardness, roughness, and wettability of the CP-titanium surfaces were investigated in this paper. The thermal oxidation treatment was done at 700 oC for 12-36 hours in an air atmosphere. The wear behavior of the UHMWPE sliding against treated thermal oxidation of the CP-titanium was tested by a pin-on-plate tribometer under lubrication of the solution of 75 % distilled water and 25 % bovine serum. The results showed that the layer of the oxide titanium was formed on the surface after being treated by the thermal oxidation for 12-36 hours. The oxide titanium layer was dominated by rutile form of TiO2, that offers an improvement of hardness and wettability of the CP-titanium surfaces. The average wear factor of the UHMWPE reduced significantly when the sliding against of the CP-titanium was modified by the thermal oxidation, and the lowest average wear factor was reached when the sliding against the 12 hour oxidized CP-titanium counterfaces.

  9. Exploring the origins of the apparent "electrocatalytic" oxidation of kojic acid at graphene modified electrodes.

    Science.gov (United States)

    Figueiredo-Filho, Luiz C S; Brownson, Dale A C; Fatibello-Filho, Orlando; Banks, Craig E

    2013-08-21

    We explore the recent reports that the use of graphene modified electrodes gives rise to the electrocatalytic oxidation of kojic acid. It is demonstrated that large quantifiable voltammetric signatures are observed on bare/unmodified graphitic electrodes, which are shown to be analytically useful and superior to those observed at graphene modified alternatives. This work is of importance as it shows that control experiments are critical and must be undertaken before "electrocatalysis" is conferred when investigating graphene in electrochemistry. In terms of the electroanalytical response of graphene modified electrodes, a bare edge plane pyrolytic graphite electrode is shown to give rise to an improved linear range and limit of detection, questioning the need to modify electrodes with graphene.

  10. Electrooxidation of catecholamines at carbon nanotube-modified indium tin oxide electrodes.

    Science.gov (United States)

    Lin, Kuan-Wen; Lin, Chang-Hao; Hsieh, You-Zung

    2008-06-30

    In this study, we prepared carbon nanotube (CNT)/Nafion-modified ITO electrodes and investigated their electrochemical behavior. The CNTs were dissolved in a solution of the ionic polymer Nafion and then CNT/Nafion composite films were deposited onto ITO electrodes through spin-coating of this homogeneous solution. We studied the effects of chemical pretreatment of the CNTs and the pH of the buffer on the electroanalytical behavior of the CNT/Nafion-modified ITO electrodes toward catecholamines. The modified electrodes enhanced the peak current and lowered the overpotentials. We observed high electrooxidative performance for the modified ITO electrodes: the oxidative currents of the catecholamines were up to 125-fold higher than those obtained using bare ITO electrodes.

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

    International Nuclear Information System (INIS)

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

    1986-01-01

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

  12. Synthesis, characterisation and electrochemical evaluation of reduced graphene oxide modified antimony nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Silwana, Bongiwe; Horst, Charlton van der [Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Stellenbosch 7600 (South Africa); SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535 (South Africa); Iwuoha, Emmanuel [SensorLab, Department of Chemistry, University of the Western Cape, Bellville 7535 (South Africa); Somerset, Vernon, E-mail: vsomerset@csir.co.za [Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Stellenbosch 7600 (South Africa)

    2015-10-01

    This paper demonstrates some aspects on the synthesis and characterisation of nanoparticles of metallic alloys using polyvinyl alcohol as a stabiliser, which combines high surface area and superior hybrid properties. The present experimental design was to synthesise a nanocomposite of reduced graphene oxide and antimony nanoparticles to be used as thin films for macro- and micro-carbon electrodes for enhancing sensing of different toxic metal pollutants in the environment. The synthetic process of reduced graphene oxide was done using the modified Hummers method while antimony pentachloride was reduced with sodium borohydride into nanoparticles of antimony using polyvinyl-alcohol as a stabiliser. The systematic investigation of morphology was done by scanning electron microscopy and high resolution-transmission electron microscope, which revealed the synthesis of a product, consists of reduced graphene oxide antimony nanoparticles. The electrochemical behaviour of the reduced graphene oxide antimony nanoparticles coated on a glassy carbon electrode was performed using voltammetric and impedance techniques. Electrochemical impedance measurements showed that the overall resistance, including the charge–transfer resistance, was smaller with reduced graphene oxide antimony nanoparticles than reduced graphene oxide and antimony nanoparticles, on their own. Evaluation of the reduced graphene oxide antimony nanoparticle sensor in the stripping voltammetry has shown a linear working range for concentration of platinum (II) between 6.0 × 10{sup −6}–5.4 × 10{sup −5} μg L{sup −1} with limit of detection of 6 × 10{sup −6} μg L{sup −1} (signal-to-noise ratio = 3), which is below the World Health Organisation guidelines for freshwater. - Highlights: • Reduced graphene oxide modified antimony nanoparticles were chemically synthesised. • TEM results show rGO-Sb nanoparticles with a diameter range of between 2 and 20 nm. • Impedance results confirm

  13. Synthesis of silane ligand-modified graphene oxide and antibacterial activity of modified graphene-silver nanocomposite.

    Science.gov (United States)

    Fathalipour, Soghra; Mardi, Mojtaba

    2017-10-01

    In this research, a new type of chemically modified graphene oxide (GO) was synthesized based a silane ligand and then used as substrate and stabilizing for the synthesis of monodispersed and small Ag nanoparticles (NPs). First, ligand molecules were successfully grafted onto the surface of GO (LGO) and then, active groups of LGO could effectively interact with Ag ions. The reduction of Ag ions and LGO sheets was carried out by hydrazine under reflux. The resulted nanocomposite was fully characterized by different techniques. Furthermore, the antibacterial behavior of nanocomposite was studied against E. coli and S. aureus. The results showed that nanocomposite exhibits good antibacterial activity against E. coli and S. aureus and also S. aureus showed greater resistance than the E. coli strains against the LG/Ag nanocomposite. Copyright © 2017. Published by Elsevier B.V.

  14. Effect of chemical heterogeneity on photoluminescence of graphite oxide treated with S-/N-containing modifiers

    Science.gov (United States)

    Ebrahim, Amani M.; Rodríguez-Castellón, Enrique; Montenegro, José María; Bandosz, Teresa J.

    2015-03-01

    Graphite oxide (GO) obtained using Hummers method was modified by hydrothermal treatment either with sulfanilic acid or polystyrene (3-ammonium) sulfonate at 100 °C or 85 °C, respectively. Both modifiers contain sulfur in the oxidized forms and nitrogen in the reduced forms. The materials were characterized using FTIR, XPS, thermal analysis, potentiometric titration and SEM. Their photoluminescent properties and their alteration with an addition of Ag+ were also measured. As a result of these modifications nitrogen was introduced to the graphene layers as amines, imides, amides, and sulfur as sulfones and sulfonic acids. Moreover, the presence of polyaniline was detected. This significantly affected the polarity, acid-base character, and conductivity of the materials. Apparently carboxylic groups of GO were involved in the surface reactions. The modified GOs lost their layered structure and the modifications resulted in the high degree of structural and chemical heterogeneity. Photoluminescence in visible light was recorded and linked to the presence of heteroatoms. For the polystyrene (3-ammonium) sulfonate modified sample addition of Ag+ quenched the photoluminescence at low wavelength showing sensitivity as a possible optical detector. No apparent effect was found for the sulfanilic acid modified sample.

  15. Oxidatively modified LDL particles in the human placenta in early and late onset intrauterine growth restriction.

    Science.gov (United States)

    Pecks, U; Rath, W; Caspers, R; Sosnowsky, K; Ziems, B; Thiesen, H-J; Maass, N; Huppertz, B

    2013-12-01

    Reduced serum LDL concentrations have been observed in pregnancies complicated by intrauterine growth restriction (IUGR) as compared to healthy pregnant women. Since increased oxidative stress has been suggested to play a major role in IUGR we now hypothesized that the lower LDL concentrations are accompanied by an accumulation of oxidized LDLs in the placenta. Fifteen placentas of near term and preterm born IUGR, and a gestational age matched control group (CTRL n = 15) were analyzed. Placental minimal modified LDL and fully oxidized LDL particles were measured by ELISA, and by immunohistochemistry, and were related to maternal and fetal serum lipid profiles. We found fully oxidized LDL but not minimal modified LDL being increased in the preterm subgroup of IUGR (n = 10) as compared to preterm CTRL (n = 10; p placenta possibly taking place in preterm IUGRs. We conclude that the reduced maternal LDL cholesterol concentration in IUGR pregnancies is attributed to increased accumulation of oxidized LDL particles within the placenta at least in early onset IUGR

  16. Oxidative stress and ischemia-modified albumin in chronic ischemic heart failure.

    Science.gov (United States)

    Ellidag, Hamit Yasar; Eren, Esin; Yılmaz, Necat; Cekin, Yesim

    2014-05-01

    Knowledge about the role of oxidative stress in human diseases, including cardiovascular system disorders, emphasizes the need for reliable markers of oxidative stress. Here, we evaluated the levels of the novel marker ischemia-modified albumin (IMA), albumin-adjusted IMA (adj-IMA), and the IMA/serum albumin ratio (IMAR) in patients with chronic ischemic heart failure (CIHF). A total of 55 patients with CIHF and 40 age- and sex-matched healthy individuals were included in the study. Serum levels of IMA, total antioxidant status, and total oxidant status were analyzed, and the adj-IMA level, IMAR, and oxidative stress index were calculated. Serum IMA, IMAR, total oxidant status levels, and oxidative stress index were significantly higher in patients with CIHF than in the controls (all P stress in CIHF patients. Oxidative stress may be a key factor in the development of hypoalbuminemia in CIHF. Further studies are needed to establish the relationships among IMA, albumin, and redox balance in CIHF.

  17. Iron modified titanium–hafnium binary oxides as catalysts in total oxidation of ethyl acetate

    Czech Academy of Sciences Publication Activity Database

    Tsoncheva, T.; Ivanova, R.; Henych, Jiří; Velinov, N.; Kormunda, M.; Dimitrov, M.; Paneva, D.; Slušná, Michaela; Mitov, I.; Štengl, Václav

    2016-01-01

    Roč. 81, JUN (2016), s. 14-19 ISSN 1566-7367 R&D Projects: GA MŠk LM2015073 Institutional support: RVO:61388980 Keywords : Titania–hafnia binary oxides * Iron modifications * Support effect * Ethyl acetate oxydation Subject RIV: CA - Inorganic Chemistry Impact factor: 3.330, year: 2016

  18. Effect of process parameters on removal and recovery of Cd(II) and Cu(II) from electroplating wastewater by fixed-bed column of nano-dimensional titanium (IV) oxide agglomerates

    CSIR Research Space (South Africa)

    Debnath, S

    2014-01-01

    Full Text Available Removal performances of Cd(II) and Cu(II) from water was investigated using agglomerated nanoparticle of hydrous titanium(IV) oxide (NTO) packed fixed bed. The parameters varied were the bed depth, flow rate and feed solution concentrations...

  19. Polyacrylamide grafting of modified graphene oxides by in situ free radical polymerization

    International Nuclear Information System (INIS)

    Tang, Mingyi; Xu, Xiaoyang; Wu, Tao; Zhang, Sai; Li, Xianxian; Li, Yi

    2014-01-01

    Highlights: • Graphene oxide (GO) was modified by chemical reactions to functionalized GO (FGO). • The FGOs and the GO were then subjected to in situ free radical polymerization. • Hydroxyl groups of GO were the most reactive grafting sites. - Abstract: Graphene oxide (GO) was modified using chemical reactions to obtain three types of functionalized GO sheets (FGO). The FGO sheets and the GO were then subjected to in situ free radical polymerization in order to study the grafting polymerization. The FGO and grafted-.FGO were analyzed with Fourier transform infrared spectroscopy, scanning electronic microscopy, thermo-gravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The grafting percentages in the materials were calculated using the TGA and XPS results. The FGO sheets with different functional groups exhibited different grafting abilities, and hydroxyl groups were proven to be the most reactive grafting sites for the in situ free radical grafting polymerization of polyacrylamide

  20. Effective Removal of Hexavalent Chromium from Aqueous Solutions Using Ionic Liquid Modified Graphene Oxide Sorbent

    Directory of Open Access Journals (Sweden)

    A. Nasrollahpour

    2017-10-01

    Full Text Available Ionic liquid modified reduced graphene oxide (IL-rGO was prepared and examined for chromate removal. The sorbent was characterized by N2 adsorption-desorption measurement (BET, transmission electron microscopy (TEM, powder X-ray diffraction (XRD, and X-ray photoelectron spectroscopy (XPS analysis. The sorption behavior of chromate on the ionic liquid modified reduced graphene oxide sorbent from an aqueous medium was studied by varying the parameters such as contact time, initial chromate concentration, pH, and agitation speed. The results showed that sorption kinetics of chromate by IL-rGO follows the pseudo second order, which indicates that the sorption mechanism is both chemical and physical interaction. The sorption isotherm studies revealed that Langmuir model provided the best fit to all the experimental data with an adsorption capacity of 232.55 mg g–1 for IL-rGO. Thermodynamic parameters, such as Gibbs free energy (–2.85 kJ mol–1 at 298 K, enthalpy (55.41 kJ mol–1, and entropy (11.64 J mol–1 K–1 of sorption of the chromate on ionic liquid modified reduced graphene oxide was evaluated, and it was found that the reaction was spontaneous and endothermic in nature.

  1. Fast and Straightforward Synthesis of Luminescent Titanium(IV) Dioxide Quantum Dots

    Czech Academy of Sciences Publication Activity Database

    Štengl, Václav; Henych, Jiří; Šťastný, Martin; Kormunda, M.

    2017-01-01

    Roč. 2017, JUL (2017), č. článku 3089091. ISSN 1687-4110 R&D Projects: GA MPO(CZ) FV10480 Institutional support: RVO:61388980 Keywords : lung epithelial-cells * interface * oxidation * toxicity * surface * Ti Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 1.871, year: 2016

  2. Synthesis and characterization of Tamoxifen citrate modified reduced graphene oxide nano sheets for breast cancer therapy.

    Science.gov (United States)

    Zhang, Yu-Jin; Li, Bao-An; Li, Zhao-Yuan; Xia, Ning; Yu, Hai-Ying; Zhang, Ya-Zhi

    2018-03-01

    Theranostic agents are of immense consideration in the current generation nanomedicine. In this study, we have developed a facile approach for the fabrication of Tamoxifen citrate modified nanosized reduced graphene oxide (nano-rGO) with more stability and low cytotoxicity. The prepared nano-rGO sheets were characterized using HR-TEM and AFM imaging techniques. Further, the cytotoxicity was assessed using MTT assay on female BALB/c nude mice MCF-7 cell lines. In addition, by means of continuous-wave near-infrared laser, cancer cells in vivo were significantly ablated because of the photothermal effect stimulated by tamoxifen modified nano-rGO. These results indicated that the prepared tamoxifen modified nano-rGO has the ability to apply in the photothermal therapy of breast cancers. Consequently, further exploration of photothermal therapeutics is desirable for the synthesis of novel nano materials with additional functionalities. Copyright © 2017. Published by Elsevier B.V.

  3. Highly sensitive electrochemical determination of nitric oxide using fused spherical gold nanoparticles modified ITO electrode

    Energy Technology Data Exchange (ETDEWEB)

    Kannan, P. [Department of Chemistry, Gandhigram Rural University, Gandhigram 624 302, Dindigul, Tamil Nadu (India); John, S. Abraham, E-mail: abrajohn@yahoo.co.i [Department of Chemistry, Gandhigram Rural University, Gandhigram 624 302, Dindigul, Tamil Nadu (India)

    2010-04-01

    This paper describes the highly sensitive electrochemical determination of nitric oxide (NO) using the fused spherical gold nanoparticles (FAuNPs) modified ITO electrode. The FAuNPs were self-assembled on a (3-mercaptopropyl)-trimethoxysilane (MPTS) sol-gel film, which was preassembled on ITO electrode. The attachment of FAuNPs on MPTS sol-gel film was confirmed by UV-vis absorption spectroscopy, atomic force microscopy (AFM) and cyclic voltammetry (CV). The AFM image shows that the AuNPs retain their fused morphology after immobilized on MPTS sol-gel film. The FAuNPs modified ITO electrode shows an excellent electrocatalytic activity towards the oxidation of NO. Using FAuNPs modified electrode, the detection of 12 nM NO was achieved for the first time by amperometry method. Further, the current response was increased linearly with increasing NO concentration in the range of 1.2 x 10{sup -8} to 7 x 10{sup -4} M and the detection limit was found to be 3.1 x 10{sup -10} M (S/N = 3). The FAuNPs modified ITO electrode displays an excellent selectivity towards the determination of 12 nM NO even in the presence of 1000-fold excess common interfering agents.

  4. Application of graphene oxide/lanthanum-modified carbon paste electrode for the selective determination of dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Fengying; Feng, Chenqi; Fu, Ning; Wu, Huihui; Jiang, Jibo, E-mail: jibojiang0506@163.com; Han, Sheng, E-mail: hansheng654321@sina.com

    2015-12-01

    Highlights: • The effective surface area of the modified CPE has been expanded after self-assembly. • The GO–La composite exhibited excellent electrocatalytic activity toward DA. • The GO–La/CPE presented high selectivity, sensitivity, excellent stability and repeatability. - Abstract: A home-made carbon paste electrode (CPE) was reformed by graphene oxide (GO)/lanthanum (La) complexes, and a modified electrode, called GO–La/CPE, was fabricated for the selective determination of dopamine (DA) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV). Several factors affecting the electrocatalytic performance of the modified sensor were investigated. Owning to the combination of GO and La ions, the GO–La/CPE sensor exhibited large surface area, well selectivity, good repeatability and stability in the oxidation reaction of DA. At optimal conditions, the response of the GO–La/CPE electrode for determining DA was linear in the region of 0.01–0.1 μM and 0.1–400.0 μM. The limit of detection was down to 0.32 nM (S/N = 3). In addition, this modified electrode was successfully applied to the detection of DA in real urine and serum samples by using standard adding method, showing its promising application in the electroanalysis of real samples.

  5. Pyrene Removal from Contaminated Soils by Modified Fenton Oxidation Using Iron Nano Particles

    Directory of Open Access Journals (Sweden)

    Sahand Jorfi

    2013-07-01

    Full Text Available Background:The problems related to conventional Fenton oxidation, including low pH required and production of considerable amounts of sludge have led researchers to investigate chelating agents which might improve the operating range of pH and the use of nano iron particle to reduce the excess sludge. The pyrene removal from contaminated soils by modified Fenton oxidation at neutral pH was defined as the main objective of the current study.Methods:Varying concentrations of H2O2 (0-500 mM and iron nano oxide (0-60 mM, reaction times of 0.5-24 hours and variety of chelating agents including sodium pyrophosphate, sodium citrate, ethylene diamine tetraacetic, fulvic and humic acid were all investigated at pyrene concentration levels of 100 – 500 mg/kg.Results:By applying the following conditions (H2O2 concentration of 300 mM, iron nano oxide of 30 mM, sodium pyrophosphate as chelating agent, pH 3 and reaction time of 6 hours the pyrene removal efficiency at an initial concentration of 100 mg/kg was found to be 99%. As a result, the pyrene concentration was reduced from 100 to 93 mg/kg once the above optimum conditions are met.Conclusions:In this research, the modified Fenton oxidation using iron nano oxide at optimum conditions is introduced as an efficient alternative method in lab scale for chemical remediation or pre-treatment of soils contaminated by pyrene at neutral pH.

  6. The Application of a Modified d-ROMs Test for Measurement of Oxidative Stress and Oxidized High-Density Lipoprotein

    Directory of Open Access Journals (Sweden)

    Fumiaki Ito

    2017-02-01

    Full Text Available Reactive oxygen species (ROS are involved in the initiation and progression of atherosclerosis. ROS-derived hydroperoxides, as an indicator of ROS production, have been measured by using the diacron reactive oxygen metabolites (d-ROMs test, which requires iron-containing transferrin in the reaction mixture. In this study we developed a modified d-ROMs test, termed the Fe-ROMs test, where iron ions were exogenously added to the reaction mixture. This modification is expected to exclude the assay variation that comes from different blood iron levels in individuals. In addition, this Fe-ROMs test was helpful for determining the class of plasma lipoproteins that are hydroperoxidized. Low-density lipoprotein/very low-density lipoprotein (LDL/VLDL and high-density lipoprotein (HDL were purified by use of an LDL/VLDL purification kit and the dextran sulfate-Mg2+ precipitation method, respectively; their hydroperoxide contents were assessed by performing the Fe-ROMs test. The majority of the hydroperoxides were detected only in the HDL fraction, not in the LDL/VLDL. Further detailed analysis of HDLs by size-exclusion high-performance liquid chromatography revealed that the hydroperoxide-containing molecules were small-sized HDLs. Because HDL was shown to be the principal vehicle for the plasma hydroperoxides, this Fe-ROMs test is a beneficial method for the assessment of oxidized-HDL levels. Indeed, Fe-ROMs levels were strongly associated with the levels of oxidized HDL, which were determined by performing the malondialdehyde-modified HDL enzyme immunoassay. In conclusion, the Fe-ROMs test using plasma itself or the HDL fraction after dextran sulfate-Mg2+ precipitation is useful to assess the functionality of HDL, because the oxidation of HDL impairs its antiatherogenic capacity.

  7. Simultaneous Electrochemical Detection of Dopamine and Ascorbic Acid Using an Iron Oxide/Reduced Graphene Oxide Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Teo Peik-See

    2014-08-01

    Full Text Available The fabrication of an electrochemical sensor based on an iron oxide/graphene modified glassy carbon electrode (Fe3O4/rGO/GCE and its simultaneous detection of dopamine (DA and ascorbic acid (AA is described here. The Fe3O4/rGO nanocomposite was synthesized via a simple, one step in-situ wet chemical method and characterized by different techniques. The presence of Fe3O4 nanoparticles on the surface of rGO sheets was confirmed by FESEM and TEM images. The electrochemical behavior of Fe3O4/rGO/GCE towards electrocatalytic oxidation of DA was investigated by cyclic voltammetry (CV and differential pulse voltammetry (DPV analysis. The electrochemical studies revealed that the Fe3O4/rGO/GCE dramatically increased the current response against the DA, due to the synergistic effect emerged between Fe3O4 and rGO. This implies that Fe3O4/rGO/GCE could exhibit excellent electrocatalytic activity and remarkable electron transfer kinetics towards the oxidation of DA. Moreover, the modified sensor electrode portrayed sensitivity and selectivity for simultaneous determination of AA and DA. The observed DPVs response linearly depends on AA and DA concentration in the range of 1–9 mM and 0.5–100 µM, with correlation coefficients of 0.995 and 0.996, respectively. The detection limit of (S/N = 3 was found to be 0.42 and 0.12 µM for AA and DA, respectively.

  8. Conductometric gas sensors based on metal oxides modified with gold nanoparticles: a review

    International Nuclear Information System (INIS)

    Korotcenkov, Ghenadii; Cho, Beong K.; Brinzari, Vladimir

    2016-01-01

    This review (with 170 refs.) discusses approaches towards surface functionalizaton of metal oxides by gold nanoparticles, and the application of the resulting nanomaterials in resistive gas sensors. The articles is subdivided into sections on (a) methods for modification of metal oxides with gold nanoparticles; (b) the response of gold nanoparticle-modified metal oxide sensors to gaseous species, (c) a discussion of the limitations of such sensors, and (d) a discussion on future tasks and trends along with an outlook. It is shown that, in order to achieve significant improvements in sensor parameters, it is necessary to warrant a good control the size and density of gold nanoparticles on the surface of metal oxide crystallites, the state of gold in the cluster, and the properties of the metal oxide support. Current challenges include an improved reproducibility of sensor preparation, better long-term stabilities, and a better resistance to sintering and poisoning of gold clusters during operation. Additional research focused on better understanding the role of gold clusters and nanoparticles in gas-sensing effects is also required. (author)

  9. Two-Sided Surface Oxidized Cellulose Membranes Modified with PEI: Preparation, Characterization and Application for Dyes Removal

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2017-09-01

    Full Text Available Porous regenerated cellulose (RC membranes were prepared with cotton linter pulp as a raw material. These membranes were first oxidized on both sides by a modified (2,2,6,6-tetramethylpiperidin-1-yloxyl (TEMPO oxidation system using a controlled oxidation reaction technique. Then, the oxidized RC membranes were functionalized with polyethylenimine (PEI via the glutaraldehyde crosslinking method to obtain bifunctional (carboxyl and amino porous RC membranes, as revealed by Fourier transform infrared spectroscopy (FT-IR, elemental analysis and zeta potential measurement. The scanning electron microscopy (SEM and the tests of the mechanical properties and permeability characteristics of modified RC membranes demonstrated that the porous structure and certain mechanical properties could be retained. The adsorption performance of the modified membranes towards dyes was subsequently investigated. The modified membranes displayed good adsorption capacities, rapid adsorption equilibrium and removal efficiencies towards both anionic (xylenol orange (XO and cationic (methylene blue (MB dyes, making them suitable bioadsorbents for wastewater treatment.

  10. Efficiency of bimetallic PtPd on polydopamine modified on various carbon supports for alcohol oxidations

    Science.gov (United States)

    Pinithchaisakula, A.; Ounnunkad, K.; Themsirimongkon, S.; Promsawan, N.; Waenkaew, P.; Saipanya, S.

    2017-02-01

    In this work, the preparation, characterization, and electrocatalytic analysis of the catalysts on various carbon substrates for direct alcohol fuel cells were studied. Selected carbons were modified with/without polydopamine (labelled as PDA-C and C) and further metal electrodeposited incorporated onto the glassy carbon (labelled as 5Pt1Pd/PDA-C and 5Pt1Pd/C). Four various carbon materials were used e.g. graphite (G), carbon nanotube (CNT), graphene (GP) and graphene oxide (GO) and the carbons were modified with PDA denoted as PDA-G, PDA-CNT, PDA-GP and PDA-GO, respectively. The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) experimental observation showed narrow size distribution of metal anchored on the PDA-C and C materials. Chemical compositions and oxidation states of the catalysts were determined by X-ray photoelectron spectroscopy (XPS) and energy-dispersive X-ray spectroscopy (EDX). The catalytic performances for small organic electro-oxidation (e.g. methanol and ethanol) were measured by cyclic voltammetry (CV). Among different PDA-C and C catalysts, monometallic Pt showed less activity than the bimetallic catalysts. Among catalysts with PDA, the 5Pt1Pd/PDA-GO catalyst facilitated methanol and ethanol oxidations with high oxidation currents and If/Ib value and stability with low potentials while among catalysts without PDA, the 5Pt1Pd/CNT provides highest activity and stability. It was found that the catalysts with PDA provided high activity and stability than the catalysts without PDA. The improved catalytic performance of the prepared catalysts could be related to the higher active surface area from polymer modification and bimetallic catalyst system in the catalyst composites.

  11. Coupling catalytic hydrolysis and oxidation of HCN over HZSM-5 modified by metal (Fe,Cu) oxides

    Science.gov (United States)

    Hu, Yanan; Liu, Jiangping; Cheng, Jinhuan; Wang, Langlang; Tao, Lei; Wang, Qi; Wang, Xueqian; Ning, Ping

    2018-01-01

    In this work, a series of metal oxides (Fe,Cu) modified HZSM-5 catalysts were synthesized by incipient-wetness impregnation method and then characterized by XRD, N2 adsorption-desorption, H2-TPR, NH3-TPD, UV-vis, FT-IR and XPS measurements. The catalytic hydrolysis and oxidation behaviors toward HCN were investigated. The results indicated that the Fe-Cu/HZSM-5 catalysts exhibited more excellent performence on coupling catalytic hydrolysis and oxidation of HCN than HZSM-5, Fe/HZSM-5, Cu/HZSM-5, and both nearly 100% HCN conversion and 80% N2 selectivity were obtained at about 250 °C. The improved catalytic performance could be ascribed to the creation of highly dispersed iron and copper composites on the surface of the HZSM-5 support, the excellent redox and regulated acid properties of the active ingredients. Moreover, the highly N2 selectivity could be attributed to the good interaction between the Fe and Cu nanocomposites which was facilitated to the NH3-SCR (selective catalytic reduction of NO by NH3) reaction.

  12. Active Bilayer PE/PCL Films for Food Packaging Modified with Zinc Oxide and Casein

    Directory of Open Access Journals (Sweden)

    Ana Rešček

    2015-12-01

    Full Text Available This paper studies the properties of active polymer food packaging bilayer polyethylene/polycaprolactone (PE/PCL films. Such packaging material consists of primary PE layer coated with thin film of PCL coating modified with active component (zinc oxide or zinc oxide/casein complex with intention to extend the shelf life of food and to maintain the quality and health safety. The influence of additives as active components on barrier, mechanical, thermal and antimicrobial properties of such materials was studied. The results show that, in comparison to the neat PE and PE/PCL films, some of PE/PCL bilayer films with additives exhibit improved barrier properties i.e. decreased water vapour permeability. Higher thermal stability of modified PE/PCL material is obtained due to a modified mechanism of thermal degradation. The samples with the additive nanoparticles homogeneously dispersed in the polymer matrix showed good mechanical properties. Addition of higher ZnO content contributes to the enhanced antibacterial activity of a material.

  13. Oxidation and textural characteristics of butter and ice cream with modified fatty acid profiles.

    Science.gov (United States)

    Gonzalez, S; Duncan, S E; O'Keefe, S F; Sumner, S S; Herbein, J H

    2003-01-01

    The primary objective of this study was to evaluate oxidation and firmness of butter and ice cream made with modified milkfat containing enhanced amounts of linoleic acid or oleic acid. The influence of the fatty acid profile of the HO milkfat relating to product properties as compared with the influence the fatty acid profile of the HL milkfat was the main focus of the research. Altering the degree of unsaturation in milkfat may affect melting characteristics and oxidation rates, leading to quality issues in dairy products. Three milkfat compositions (high-oleic, high-linoleic, and control) were obtained by modifying the diets of Holstein cows. Ice cream and butter were processed from milkfat obtained from cows in each dietary group. Butter and ice cream samples were analyzed to determine fatty acid profile and firmness. High-oleic milkfat resulted in a softer butter. Solid fat index of high-oleic and high-linoleic milkfat was lower than the control. Control ice cream mix had higher viscosity compared with high-oleic and high-linoleic, but firmness of all ice creams was similar when measured between -17 and -13 degrees C. Nutritional and textural properties of butter and ice cream can be improved by modifying the diets of cows.

  14. Electrochemical oxidation of pulp and paper making wastewater assisted by transition metal modified kaolin

    International Nuclear Information System (INIS)

    Wang Bo; Gu Lin; Ma Hongzhu

    2007-01-01

    The electrochemical oxidation of pulp and paper making wastewater assisted by transition metal (Co, Cu) modified kaolin in a 200 ml electrolytic batch reactor with graphite plate as electrodes was investigated. H 2 O 2 , which produced on the surface of porous graphite cathode, would react with the catalysts to form strong oxidant (hydroxyl radicals) that can in turn destruct the pollutants adsorbed on the surface of kaolin. The transition metal (Co, Cu) modified kaolin was also characterized by XRD and SEM before and after the modification and the results showed that the transition metals were completely supported on kaolin and formed a porous structure with big BET surface. The mechanism was proposed on the basis of XPS analysis of the catalyst after the degradation process. Series of experiments were also done to prove the synergetic effect of the combined oxidation system and to find out the optimal operating parameters such as initial pH, current density and amount of catalyst. From the results it can be founded that when the initial pH was at 3, current density was 30 mA cm -2 ; catalyst dose was 30 g dm -3 , COD (chemical oxygen demand) removal could reach up to 96.8% in 73 min

  15. Surface charge-transfer complex formation of catechol on titanium(IV) oxide and the application to bio-sensing.

    Science.gov (United States)

    Murata, Yusuke; Hori, Hiroshige; Taga, Atsushi; Tada, Hiroaki

    2015-11-15

    Adsorption properties of 2-hydroxyphenol (catechol) on TiO2 particles has been studied at 298K. The adsorption proceeds from the aqueous solution with the Langmuir type behavior. Diffuse reflectance infrared spectra of the catechol-adsorbed TiO2 suggested that catechol is adsorbed on TiO2 solution via the chelation to the surface Ti ions. The adsorption induces a strong absorption in the whole visible region, of which intensity increases with an increase in the adsorption amount. Photoelectrochemical experiments and molecular orbital calculations indicate that the absorption stems from the charge-transfer (CT) transition from the HOMO of catechol to the conduction band of TiO2. Time courses for the adsorption of catechol on mesoporous TiO2 nanocrystalline film-coated glass was traced by measuring the change in the absorbance of the CT band, and analyzed on the basis of the Langmuir model. This study would present a new simple technique for sensing of important biomolecules bearing the catechol moiety. Copyright © 2015. Published by Elsevier Inc.

  16. Microwave Photocatalysis of Mono-Chloroacetic Acid over Nanoporous Titanium(IV) Oxide Thin Films Using Mercury Electrodeless Discharge Lamps

    Czech Academy of Sciences Publication Activity Database

    Církva, Vladimír; Žabová, Hana; Hájek, Milan

    2008-01-01

    Roč. 198, č. 1 (2008), s. 13-17 ISSN 1010-6030 R&D Projects: GA ČR GA104/06/0992; GA ČR GA104/07/1212 Institutional research plan: CEZ:AV0Z40720504 Keywords : microwave-assisted photocatalysis * electrodeless discharge lamp * mono-chloroacetic acid Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 2.362, year: 2008

  17. Antenatal insults modify newborn olfactory function by nitric oxide produced from neuronal nitric oxide synthase.

    Science.gov (United States)

    Drobyshevsky, Alexander; Yu, Lei; Yang, Yirong; Khalid, Syed; Luo, Kehuan; Jiang, Rugang; Ji, Haitao; Derrick, Matthew; Kay, Leslie; Silverman, Richard B; Tan, Sidhartha

    2012-10-01

    Newborn feeding, maternal, bonding, growth and wellbeing depend upon intact odor recognition in the early postnatal period. Antenatal stress may affect postnatal odor recognition. We investigated the exact role of a neurotransmitter, nitric oxide (NO), in newborn olfactory function. We hypothesized that olfactory neuron activity depended on NO generated by neuronal NO synthase (NOS). Utilizing in vivo functional manganese enhanced MRI (MEMRI) in a rabbit model of cerebral palsy we had shown previously that in utero hypoxia-ischemia (H-I) at E22 (70% gestation) resulted in impaired postnatal response to odorants and poor feeding. With the same antenatal insult, we manipulated NO levels in the olfactory neuron in postnatal day 1 (P1) kits by administration of intranasal NO donors or a highly selective nNOS inhibitor. Olfactory function was quantitatively measured by the response to amyl acetate stimulation by MEMRI. The relevance of nNOS to normal olfactory development was confirmed by the increase of nNOS gene expression from fetal ages to P1 in olfactory epithelium and bulbs. In control kits, nNOS inhibition decreased NO production in the olfactory system and increased MEMRI slope enhancement. In H-I kits the MEMRI slope did not increase, implicating modification of endogenous NO-mediated olfactory function by the antenatal insult. NO donors as a source of exogenous NO did not significantly change function in either group. In conclusion, olfactory epithelium nNOS in newborn rabbits probably modulates olfactory signal transduction. Antenatal H-I injury remote from delivery may affect early functional development of the olfactory system by decreasing NO-dependent signal transduction. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. Preparation of Phosphonic Acid Functionalized Graphene Oxide-modified Aluminum Powder with Enhanced Anticorrosive Properties

    Science.gov (United States)

    He, Lihua; Zhao, Yan; Xing, Liying; Liu, Pinggui; Wang, Zhiyong; Zhang, Youwei; Liu, Xiaofang

    2017-07-01

    To improve the anticorrosive performance of aluminum powder, a common functional filler in polymer coatings, we report a novel method to prepare graphene oxide modified aluminum powder (GO-Al) using 3-aminoproplyphosphoic acid as "link" agent. The GO nanosheets were firstly functionalized with 3-aminoproplyphosphoic acid (APSA) by the reaction of amine groups of APSA and the epoxy groups of GO. Subsequently, a layer of GO nanosheets uniformly and tightly covered the surface of flaky aluminum particle though the strong linking strength between -PO(OH)2 functional groups of the modified GO and aluminum. The hydrogen evolution experiment suggests that the GO attached on the aluminum powder could effectively improve the anticorrosive performance of the pigments.

  19. Novel in situ method (vacuum assisted electroless plating) modified porous cathode for solid oxide fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Su, Ren; Lue, Zhe; Chen, Kongfa; Ai, Na; Li, Shuyan; Wei, Bo [Center for the Condensed Matter Science and Technology, Harbin Institute of Technology, Harbin 150001 (China); Su, Wenhui [Center for the Condensed Matter Science and Technology, Harbin Institute of Technology, Harbin 150001 (China); Department of Condensed Matter Physics, Jilin University, Changchun 130023 (China); International Centre for Materials Physics, Academia Sinica, Shenyang 110015 (China)

    2008-06-15

    A novel in situ method - vacuum assisted electroless plating (VA-EP) is developed to modify the porous structure of various materials. The advantage of this method is that it can form a metal network based on the already-given structure. We utilize this method to deposit silver (VA-EPA) in porous perovskite cathode Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF) for an intermediate temperature solid oxide fuel cell (IT-SOFC) in the present research. The results of investigation show the performance of the modified cathode (VA-EPA-BSCF) enhances greatly, for example, the polarization resistance of VA-EPA-BSCF decreases by 60% at 600 C compared to BSCF. (author)

  20. Methanol electro-oxidation on platinum modified tungsten carbides in direct methanol fuel cells: a DFT study.

    Science.gov (United States)

    Sheng, Tian; Lin, Xiao; Chen, Zhao-Yang; Hu, P; Sun, Shi-Gang; Chu, You-Qun; Ma, Chun-An; Lin, Wen-Feng

    2015-10-14

    In exploration of low-cost electrocatalysts for direct methanol fuel cells (DMFCs), Pt modified tungsten carbide (WC) materials are found to be great potential candidates for decreasing Pt usage whilst exhibiting satisfactory reactivity. In this work, the mechanisms, onset potentials and activity for electrooxidation of methanol were studied on a series of Pt-modified WC catalysts where the bare W-terminated WC(0001) substrate was employed. In the surface energy calculations of a series of Pt-modified WC models, we found that the feasible structures are mono- and bi-layer Pt-modified WCs. The tri-layer Pt-modified WC model is not thermodynamically stable where the top layer Pt atoms tend to accumulate and form particles or clusters rather than being dispersed as a layer. We further calculated the mechanisms of methanol oxidation on the feasible models via methanol dehydrogenation to CO involving C-H and O-H bonds dissociating subsequently, and further CO oxidation with the C-O bond association. The onset potentials for the oxidation reactions over the Pt-modified WC catalysts were determined thermodynamically by water dissociation to surface OH* species. The activities of these Pt-modified WC catalysts were estimated from the calculated kinetic data. It has been found that the bi-layer Pt-modified WC catalysts may provide a good reactivity and an onset oxidation potential comparable to pure Pt and serve as promising electrocatalysts for DMFCs with a significant decrease in Pt usage.

  1. Exoemission and the donor-acceptor properties of zirconium dioxide modified by yttrium oxide

    International Nuclear Information System (INIS)

    Krylova, I.V.; Kharlanov, A.N.; Lunin, V.V.

    2002-01-01

    Influence of alloying component Y 2 O 3 on adsorption properties of ZrO 2 was studied by the methods of exoemission and IR spectroscopy. Radiation resistance of the ZrO 2 -Y 2 O 3 system samples under β-radiation ( 90 Sr/ 90 Y) at a dose of 20 rad was determined. Correlation between concentration of the Lewis acid centers and emissivity of alloyed samples in the range of low concentrations of Y 2 O 3 was found. The nature of exoemission and adsorption centers due to donor-acceptor character of active centers on the surface of samples of the system studied was discussed. It is shown that initially high radiation resistance of ZrO 2 decreases, when it is modified by yttrium oxide, meanwhile pure yttrium oxide features moderate enough radiation resistance of the surface [ru

  2. Voltammetric sensor for caffeine based on a glassy carbon electrode modified with Nafion and graphene oxide

    International Nuclear Information System (INIS)

    Zhao, F.; Wang, F.; Zhao, W.; Zhou, J.; Liu, Y.; Zou, L.; Ye, B.

    2011-01-01

    We report on a voltammetric sensor for caffeine that is based on a glassy carbon electrode modified with Nafion and graphene oxide (GO). It exhibits a good affinity for caffeine (resulting from the presence of Nafion), and excellent electrochemical response (resulting from the pressence of GO) for the oxidation of caffeine. The electrode enables the determination of caffeine in the range from 4.0 x 10 -7 to 8.0 x 10 -5 mol L -1 , with a detection limit of 2.0 x 10 -7 mol L -1 . The sensor displays good stability, reproducibility, and high sensitivity. It was successfully applied to the quantitative determination of caffeine in beverages. (author)

  3. Electrocatalytic oxidation of deferiprone and its determination on a carbon nanotube-modified glassy carbon electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yadegari, H. [Department of Chemistry, Faculty of Science, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of); Jabbari, A. [Department of Chemistry, Faculty of Science, K.N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of)], E-mail: jabbari@kntu.ac.ir; Heli, H.; Moosavi-Movahedi, A.A. [Institute of Biochemistry and Biophysics, University of Tehran, Tehran (Iran, Islamic Republic of); Karimian, K. [Arasto Pharmaceutical Chemicals Inc., Tehran (Iran, Islamic Republic of); Khodadadi, A. [Department of Chemical Engineering, Faculty of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

    2008-02-15

    The electrochemical behavior of the anti-thalassemia and anti-HIV replication drug, deferiprone, was investigated on a carbon nanotube-modified glassy carbon (GC-CNT) electrode in phosphate buffer solution, pH 7.40 (PBS). During oxidation of deferiprone, two irreversible anodic peaks, with E{sub 1}{sup 0}=452 and E{sub 2}{sup 0}=906mV, appeared, using GC-CNT. Cyclic voltammetric study indicated that the oxidation process is irreversible and diffusion controlled. The number of exchanged electrons in the electro-oxidation process was obtained, and the data indicated that deferiprone is oxidized via two two-electron steps. The results revealed that carbon nanotube (CNT) promotes the rate of oxidation by increasing the peak current, so that deferiprone is oxidized at lower potentials, which thermodynamically is more favorable. This result was confirmed by impedance measurements. The diffusion coefficient, electron-transfer coefficient and heterogeneous electron-transfer rate constant of deferiprone were found to be 1.49 x 10{sup -6} cm{sup 2} s{sup -1}, 0.44, and 3.83 x 10{sup -3} cm s{sup -1}, respectively. A sensitive, simple and time-saving differential-pulse voltammetric procedure was developed for the analysis of deferiprone. Using the proposed method, deferiprone can be determined with a detection limit of 5.25 x 10{sup -7} M. The applicability of the method to direct assays of spiked human serum and urine fluids is described.

  4. Electrocatalytic oxidation of some anti-inflammatory drugs on a nickel hydroxide-modified nickel electrode

    Energy Technology Data Exchange (ETDEWEB)

    Hajjizadeh, M. [Department of Chemistry, Faculty of Science, K. N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of); Jabbari, A. [Department of Chemistry, Faculty of Science, K. N. Toosi University of Technology, P.O. Box 16315-1618, Tehran (Iran, Islamic Republic of)], E-mail: jabbari@kntu.ac.ir; Heli, H.; Moosavi-Movahedi, A.A. [Institute of Biochemistry and Biophysics, University of Tehran, Tehran (Iran, Islamic Republic of); Haghgoo, S. [Center of Quality Control of Drug, Tehran (Iran, Islamic Republic of)

    2007-12-31

    The electrocatalytic oxidation of several anti-inflammatory drugs (mefenamic acid, diclofenac and indomethacin) was investigated on a nickel hydroxide-modified nickel (NHMN) electrode in alkaline solution. This oxidation process and its kinetics were studied using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy techniques. Voltammetric studies indicated that in the presence of drugs, the anodic peak current of low-valence nickel species increases, followed by a decrease in the corresponding cathodic current. This pattern indicates that drugs were oxidized on the redox mediator immobilized on the electrode surface via an electrocatalytic mechanism. A mechanism based on the electrochemical generation of Ni(III) active sites and their subsequent consumption by drugs was also investigated. The corresponding rate law under the control of charge transfer was developed and kinetic parameters were derived. In this context, the charge-transfer resistance accessible both theoretically and through impedancemetry was used as a criterion. The rate constants of the catalytic oxidation of drugs and the electron-transfer coefficients are reported. A sensitive, simple and time-saving amperometric procedure was developed for the analysis of these drugs in bulk form and for the direct assay of tablets, using the NHMN electrode.

  5. Electrocatalytic oxidation of some anti-inflammatory drugs on a nickel hydroxide-modified nickel electrode

    International Nuclear Information System (INIS)

    Hajjizadeh, M.; Jabbari, A.; Heli, H.; Moosavi-Movahedi, A.A.; Haghgoo, S.

    2007-01-01

    The electrocatalytic oxidation of several anti-inflammatory drugs (mefenamic acid, diclofenac and indomethacin) was investigated on a nickel hydroxide-modified nickel (NHMN) electrode in alkaline solution. This oxidation process and its kinetics were studied using cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy techniques. Voltammetric studies indicated that in the presence of drugs, the anodic peak current of low-valence nickel species increases, followed by a decrease in the corresponding cathodic current. This pattern indicates that drugs were oxidized on the redox mediator immobilized on the electrode surface via an electrocatalytic mechanism. A mechanism based on the electrochemical generation of Ni(III) active sites and their subsequent consumption by drugs was also investigated. The corresponding rate law under the control of charge transfer was developed and kinetic parameters were derived. In this context, the charge-transfer resistance accessible both theoretically and through impedancemetry was used as a criterion. The rate constants of the catalytic oxidation of drugs and the electron-transfer coefficients are reported. A sensitive, simple and time-saving amperometric procedure was developed for the analysis of these drugs in bulk form and for the direct assay of tablets, using the NHMN electrode

  6. Acetone sensors based on TiO2 nanocrystals modified with tungsten oxide species

    International Nuclear Information System (INIS)

    Epifani, Mauro; Comini, Elisabetta; Díaz, Raül; Genç, Aziz; Andreu, Teresa; Siciliano, Pietro; Morante, Joan R.

    2016-01-01

    TiO 2 nanocrystals were prepared by sol–gel/solvothermal processing and modified by the addition of W precursor before the solvothermal step. The W: Ti nominal atomic ratio (R W ) was fixed to 0.16 and 0.64. Surface modification of TiO 2 occurred for R W = 0.16 while for R W = 0.64 nanocomposites with WO 3 nanocrystals were obtained after heat-treatment at 500 °C. Pure TiO 2 proved to be very poorly performing in acetone sensing in all the operating conditions. Instead, the addition of both W concentrations largely enhanced the sensor response. It ranged over two orders of magnitude of conductance variation for all the tested concentrations at as low as 200 °C operating temperature. The results showed that it is possible to enhance the performance of an otherwise almost inactive oxide like TiO 2 by proper combination with another more active oxide like WO 3 . - Highlights: • Sensing architecture are synthesized, combining WO 3 and of TiO 2 nanocrystals. • Surface layers of W oxides or heterojunctions of TiO 2 and WO 3 are obtained. • Simple TiO 2 surface modification by W oxides boosts the TiO 2 acetone response. • High responses even at 200 °C show catalytic effect of WO 3 addition.

  7. Nickel/alumina catalysts modified by basic oxides for the production of synthesis gas by methane partial oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Requies, J.; Cabrero, M.A.; Barrio, V.L.; Cambra, J.F.; Gueemez, M.B.; Arias, P.L. [School of Engineering (UPV/EHU), Department of Chemical and Environmental Engineering, 48013 Bilbao (Spain); La Parola, V.; Pena, M.A.; Fierro, J.L.G. [Institute of Catalysis and Petrochemistry, CSIC, Cantoblanco, 28049 Madrid (Spain)

    2006-08-15

    In the present work, Ni/{alpha}-Al{sub 2}O{sub 3} catalysts modified with different amounts of CaO and MgO were used for the production of hydrogen by catalytic partial oxidation (CPO) and wet-CPO processes of methane. In the wet-CPO process, small additions of water were introduced into the feed of the reactor to improve both the H{sub 2} yield and methane conversion. The addition of water is also beneficial because coke formation becomes thermodynamically unfavorable. The catalysts were characterized before and after the reaction with XRD, XPS, TPR and TPO techniques. Several methane decomposition tests and methane pulse experiments were carried out with a view to correlating the ability of metal sites to activate methane in the absence of oxygen with the performance for CPO and wet-CPO reactions. (author)

  8. A highly sensitive electrochemical biosensor for catechol using conducting polymer reduced graphene oxide-metal oxide enzyme modified electrode.

    Science.gov (United States)

    Sethuraman, V; Muthuraja, P; Anandha Raj, J; Manisankar, P

    2016-10-15

    The fabrication, characterization and analytical performances were investigated for a catechol biosensor, based on the PEDOT-rGO-Fe2O3-PPO composite modified glassy carbon (GC) electrode. The graphene oxide (GO) doped conducting polymer poly (3,4-ethylenedioxythiophene) (PEDOT) was prepared through electrochemical polymerization by potential cycling. Reduction of PEDOT-GO was carried out by amperometric method. Fe2O3 nanoparticles were synthesized in ethanol by hydrothermal method. The mixture of Fe2O3, PPO and glutaraldehyde was casted on the PEDOT-rGO electrode. The surface morphology of the modified electrodes was studied by FE-SEM and AFM. Cyclic voltammetric studies of catechol on the enzyme modified electrode revealed higher reduction peak current. Determination of catechol was carried out successfully by Differential Pulse Voltammetry (DPV) technique. The fabricated biosensor investigated shows a maximum current response at pH 6.5. The catechol biosensor exhibited wide sensing linear range from 4×10(-8) to 6.20×10(-5)M, lower detection limit of 7×10(-9)M, current maxima (Imax) of 92.55µA and Michaelis-Menten (Km) constant of 30.48µM. The activation energy (Ea) of enzyme electrode is 35.93KJmol(-1) at 50°C. There is no interference from d-glucose and l-glutamic acid, ascorbic acid and o-nitrophenol. The PEDOT-rGO-Fe2O3-PPO biosensor was stable for at least 75 days when stored in a buffer at about 4°C. Copyright © 2015 Elsevier B.V. All rights reserved.

  9. Hydrocracking and hydroisomerization of long-chain alkanes and polyolefins over metal-promoted anion-modified transition metal oxides

    Energy Technology Data Exchange (ETDEWEB)

    Venkatesh, Koppampatti R.; Hu, Jianli; Tierney, John W.; Wender, Irving

    1996-12-01

    A method is described for cracking a feedstock by contacting the feedstock with a metal-promoted anion-modified metal oxide catalyst in the presence of hydrogen gas. The metal oxide of the catalyst is one or more of ZrO{sub 2}, HfO{sub 2}, TiO{sub 2} and SnO{sub 2}, and the feedstock is principally chains of at least 20 carbon atoms. The metal-promoted anion-modified metal oxide catalyst contains one or more of Pt, Ni, Pd, Rh, Ir, Ru, (Mn and Fe) or mixtures of them present between about 0.2% to about 15% by weight of the catalyst. The metal-promoted anion-modified metal oxide catalyst contains one or more of SO{sub 4}, WO{sub 3}, or mixtures of them present between about 0.5% to about 20% by weight of the catalyst.

  10. Surface Properties of PAN-based Carbon Fibers Modified by Electrochemical Oxidization in Organic Electrolyte Systems

    Directory of Open Access Journals (Sweden)

    WU Bo

    2016-09-01

    Full Text Available PAN-based carbon fibers were modified by electrochemical oxidization using fatty alcohol polyoxyethylene ether phosphate (O3P, triethanolamine (TEOA and fatty alcohol polyoxyethylene ether ammonium phosphate (O3PNH4 as organic electrolyte respectively. Titration analysis, single fiber fracture strength measurement and field emission scanning electron microscopy (FE-SEM were used to evaluate the content of acidic functional group on the surface, mechanical properties and surface morphology of carbon fiber. The optimum process of electrochemical treatment obtained is at 50℃ for 2min and O3PNH4 (5%, mass fraction as the electrolyte with current density of 2A/g. In addition, the surface properties of modified carbon fibers were characterized by X-ray photoelectron spectroscopy (XPS and single fiber contact angle test. The results show that the hydrophilic acidic functional groups on the surface of carbon fiber which can enhance the surface energy are increased by the electrochemical oxidation using O3PNH4 as electrolyte, almost without any weakening to the mechanical properties of carbon fiber.

  11. Role of surface chemistry in modified ACF (activated carbon fiber)-catalyzed peroxymonosulfate oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shiying, E-mail: ysy@ouc.edu.cn [Key Laboratory of Marine Environment and Ecology, Ministry of Education, Qingdao 266100 (China); College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100 (China); Shandong Provincial Key Laboratory of Marine Environment and Geological Engineering (MEGE), Qingdao 266100 (China); Li, Lei [College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100 (China); Xiao, Tuo [College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100 (China); China City Environment Protection Engineering Limited Company, Wuhan 430071 (China); Zheng, Di; Zhang, Yitao [College of Environmental Science and Engineering, Ocean University of China, Qingdao 266100 (China)

    2016-10-15

    Highlights: • ACF can efficiently activate peroxymonosulfate to degrade organic pollutants. • Basic functional groups may mainly increase the adsorption capacity of ACF. • C1, N1, N2 have promoting effect on the ACF catalyzed PMS oxidation. • Modification by heat after nitric acid is also a way of ACF regeneration. - Abstract: A commercial activated carbon fiber (ACF-0) was modified by three different methods: nitration treatment (ACF-N), heat treatment (ACF-H) and heat treatment after nitration (ACF-NH), and the effects of textural and chemical properties on the ability of the metal-free ACF-catalyzed peroxymonosulfate (PMS) oxidation of Reactive Black 5 (RB5), an azo dye being difficultly adsorbed onto ACF, in aqueous solution were investigated in this work. Surface density of functional groups, surface area changes, surface morphology and the chemical state inside ACF samples were characterized by Boehm titration, N{sub 2} adsorption, scanning electron microscopy in couple with energy dispersive spectroscopy (SEM-EDS) and X-ray photoelectron spectroscopy (XPS), respectively. XPS spectra deconvolution was applied to figure out the importance of surface nitrogen-containing function groups. We found that π-π, pyridine and amine have promoting effect on the catalytic oxidation while the −NO{sub 2} has inhibitory effect on the ACF/PMS systems for RB5 destroy. Sustainability and renewability of the typical ACF-NH for catalytic oxidation of RB5 were also discussed in detail. Information about our conclusions are useful to control and improve the performance of ACF-catalyzed PMS oxidation for organic pollutants in wastewater treatment.

  12. Polyrhodanine modified anodic aluminum oxide membrane for heavy metal ions removal.

    Science.gov (United States)

    Song, Jooyoung; Oh, Hyuntaek; Kong, Hyeyoung; Jang, Jyongsik

    2011-03-15

    Polyrhodanine was immobilized onto the inner surface of anodic aluminum oxide (AAO) membrane via vapor deposition polymerization method. The polyrhodanine modified membrane was applied to remove heavy metal ions from aqueous solution because polyrhodanine could be coordinated with specific metal ions. Several parameters such as initial metal concentration, contact time and metal species were evaluated systematically for uptake efficiencies of the fabricated membrane under continuous flow condition. Adsorption isotherms of Hg(II) ion on the AAO-polyrhodanine membrane were analyzed with Langmuir and Freundlich isotherm models. The adsorption rate of Hg(II) ion on the membrane was obeyed by a pseudo-second order equation, indicating the chemical adsorption. The maximum removal capacity of Hg(II) ion onto the fabricated membrane was measured to be 4.2 mmol/g polymer. The AAO-polyrhodanine membrane had also remarkable uptake performance toward Ag(I) and Pb(II) ions. Furthermore, the polyrhodanine modified membrane could be recycled after recovery process. These results demonstrated that the polyrhodanine modified AAO membrane provided potential applications for removing the hazardous heavy metal ions from wastewater. Copyright © 2011 Elsevier B.V. All rights reserved.

  13. Preparation and Morphology Studies of Nano Zinc Oxide Obtained Using Native and Modified Chitosans

    Directory of Open Access Journals (Sweden)

    Jiunn-Fwu Lee

    2013-09-01

    Full Text Available Nano zinc oxide (ZnO with moderate surface area and high pore volume were prepared using a facile preparation method. Chitosan was utilized as both chelating and structure directing agent. The application of chitosans in this study suggested that even biowastes can be served in a productive manner economically. The surface modification of chitosan was carried out in order to increase the interaction between chitosan and zinc ions. The effect of sodium chloroacetate and isopropyl alcohol on the surface modification process was also explored. FT-IR (Fourier transform-infrared spectrometer and TGA (Thermogravimetric analyses analyses revealed that modified chitosans are more stable than those of unmodified chitosan. Among surface modified chitosans, CMC1 (1.5 M sodium chloroacetate and 75% isopropyl alcohol showed enhanced surface properties. Freundlich adsorption isotherms as preliminary studies confirmed that modified chitosan showed enhanced interaction with zinc ions. The interaction of zinc salt with chitosans produced a zinc-chitosan polymer. This finally cleaved upon calcination to produce nano ZnO. The effects of different calcination temperatures indicated that 450 °C is the optimum calcination temperature to produce the nano ZnO with favored surface area (15.45 m2/g and pore size (221.40 nm. SEM (Scanning electron microscope and TEM (Transmission electron microscope of ZnO indicated that uniform particle and shape distributions were obtained at low calcination temperature (450 °C.

  14. Thermal-fatigue and oxidation resistance of cobalt-modified Udimet 700 alloy

    International Nuclear Information System (INIS)

    Bizon, P.T.; Barrow, B.J.

    1986-04-01

    Comparative thermal-fatigue and oxidation resistances of cobalt-modified wrought Udimet 700 alloy (obtained by reducing the cobalt level by direct substitution of nickel) were determined from fluidized-bed tests. Bed temperatures were 1010 and 288 C (1850 and 550 C) for the first 5500 symmetrical 6-min cycles. From cycle 5501 to the 14000-cycle limit of testing, the heating bed temperature was increased to 1050 C (1922 F). Cobalt levels between 0 and 17 wt% were studied in both the bare and NiCrAlY overlay coated conditions. A cobalt level of about 8 wt% gave the best thermal-fatigue life. The conventional alloy specification is for 18.5% cobalt, and hence, a factor of 2 in savings of cobalt could be achieved by using the modified alloy. After 13500 cycles, all bare cobalt-modified alloys lost 10 to 13 percent of their initial weight. Application of the NiCrAlY overlay coating resulted in weight losses of 1/20 to 1/100 of that of the corresponding bare alloy

  15. Human beta-crystallins modified by backbone cleavage, deamidation and oxidation are prone to associate.

    Science.gov (United States)

    Zhang, Zhongli; Smith, David L; Smith, Jean B

    2003-09-01

    Information about beta-crystallins and their post-translational modifications has been scarce because of difficulties in isolating the individual beta-crystallins. These difficulties arise because the beta-crystallin sequences are highly homologous and because beta-crystallins undergo many age-related modifications that lead to a variety of molecular masses and a range of acidities for each crystallin. In this study, human beta-crystallins were isolated using several steps of chromatography both before and after two-dimensional gel electrophoresis. Many previously unidentified in vivo modifications, including deamidations among all beta-crystallins except betaB3, truncation of betaA3, betaB1 and betaA4, and oxidation of some methionines and tryptophans were located among the isolated beta-crystallins. Many modifications occurred before age 20 with modest increases in modification for beta-crystallins from lenses 20-87 years old. The tendency of the modified beta-crystallins to form non-covalent complexes was evident from their chromatographic behaviour. The presence in these complexes of betaB2-crystallin, the least modified and most soluble of the beta-crystallins, points to a possible role for betaB2 in solubilizing the more heavily modified beta-crystallins. The greater solubility of beta-crystallins compared with alpha- and gamma-crystallins in aging lenses may be due to beta-crystallin modifications and their non-covalent associations.

  16. High-Performance Perovskite Solar Cells Engineered by an Ammonia Modified Graphene Oxide Interfacial Layer.

    Science.gov (United States)

    Feng, Shanglei; Yang, Yingguo; Li, Meng; Wang, Jinmiao; Cheng, Zhendong; Li, Jihao; Ji, Gengwu; Yin, Guangzhi; Song, Fei; Wang, Zhaokui; Li, Jingye; Gao, Xingyu

    2016-06-15

    The introduction of an ammonia modified graphene oxide (GO:NH3) layer into perovskite-based solar cells (PSCs) with a structure of indium-tin oxide (ITO)/poly(3,4-ethylene-dioxythiophene):poly(4-styrenesulfonate) ( PSS)-GO: NH3/CH3NH3PbI3-xClx/phenyl C61-butyric acid methyl ester (PCBM)/(solution Bphen) sBphen/Ag improves their performance and perovskite structure stability significantly. The fabricated devices with a champion PCE up to 16.11% are superior in all the performances in comparison with all the reference devices without the GO:NH3 layer. To understand the improved device performances, synchrotron-based grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM), ultraviolet photoelectron spectroscopy (UPS), X-ray photoelectron spectroscopy (XPS), and UV-visible absorption measurements have been conducted on perovskite films on different substrates. It was found that these improvements should be partially attributed to the improved crystallization and preferred orientation order of peovskite structure, partially to the improved morphology with nearly complete coverage, partially to the enhanced optical absorption caused by the PSS-GO:NH3 layer, and partially to the better matched energy-level-alignment at the perovskite interface. Furthermore, the device was shown to be more stable in the ambient condition, which is clearly associated with the improved peovskite structure stability by the GO:NH3 layer observed by the GIXRD measurements. All these achievements will promote more applications of chemically modified graphene oxide interfacial layer in the PSCs as well as other organic multilayer devices.

  17. Rheological Behaviour of a Bitumen Modified with Metal Oxides Obtained by Regeneration Processes

    Directory of Open Access Journals (Sweden)

    Tullio Giuffrè

    2018-02-01

    Full Text Available Nowadays, one important challenge is to demonstrate an innovative and integrated approach for the sustainable construction of roads considering the whole life cycle of the infrastructure. Road pavements with multiple asphalt layers generally undergo prolonged environmental exposure and the alternation between solar irradiation and low temperatures. As a result, relaxation or progressive removal of the material with a negative impact on the resistance to plastic deformation occur, also leading to the formation of slits and to dimensional variations, which are commonly defined as thermal cracking. This suggests the use of suitable bitumen modifiers. For these, important parameters are the optimal mixing time and mixing temperature, in order to reduce problems related to the stability of the bitumen. Therefore, the behaviour, upon changing the temperature, of bituminous mixtures containing (as fillers a series of metal oxides coming, as secondary products, from spent acid solutions regeneration processes, was investigated. This is intended in order to recover and reuse those otherwise dangerous wastes coming from several industrial (especially, metallurgical processes. The study was aimed at evaluating the properties of bituminous blends by performing rheological tests under dynamic shear regime. More specifically, five different bitumen matrices were prepared (70/100 bitumen and blends with metal oxides and/or SBS copolymer. Results showed that the addition of iron oxides leads to an increase of the softening point and the complex modulus. The increase is even more emphasized when SBS is added to the blend.

  18. Influence of modified atmosphere packaging on protein oxidation, calpain activation and desmin degradation of beef muscles.

    Science.gov (United States)

    Fu, Qing-Quan; Ge, Qing-Feng; Liu, Rui; Wang, Hai-Ou; Zhou, Guang-Hong; Zhang, Wan-Gang

    2017-10-01

    Protein oxidation is widespread in biochemical systems. The objective of the study was to investigate the differences in protein oxidation, μ-calpain activity, desmin proteolysis and protein solubility of beef psoas major (PM) and semi-membranosus (SM) muscles under three packaging systems during postmortem ageing. At 24 h postmortem, beef muscles were packaged respectively in air-permeable film overwrap (AP), vacuum pack (VP) or modified atmosphere (MAP, 80% O 2 + 20% CO 2 ), and then displayed for 10 days at 4 °C. Carbonyl group values and thiol group content were significantly influenced by packaging type and storage time. The SM muscles from AP and MAP showed greater μ-calpain activity compared to VP. Desmin of PM and SM from AP and MAP samples showed decreased proteolysis compared with VP. The results suggested that the inhibition of μ-calpain activity of beef samples from AP and MAP could be closely associated with protein oxidation which further lowered the level of desmin degradation compared to VP. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  19. Cross-linked graphene oxide sheets via modified extracted cellulose with high metal adsorption.

    Science.gov (United States)

    Yakout, Amr A; El-Sokkary, Ramadan H; Shreadah, Mohamed A; Abdel Hamid, Omnia G

    2017-09-15

    We have studied the extraction of Cu(II) and Pb(II) ions from different types of aqueous solution by novel cross-linked graphene oxide sheets by modified extracted cellulose. The novel sorbent cellulose was extracted from the mangrove trees (Avicennia marina) and it was then grafted with acrylamide and immobilized by ethylenediamine for cross-linking process. The cross-linked graphene oxide sheets were identified by means of FT-IR, SEM and XRD. The adsorption studies of synthesized sorbent was optimized. Langmuir and Freundlich models were used for establish sorption equilibria. The cross-linked graphene oxide sheets showed maximum adsorption capacity 46.39 and 186.48mgg -1 for Cu(II) and Pb(II), respectively. The potential applications of this sorbent was applied to remove Cu(II) and Pb(II) metal ions from hard water samples by using a multi-stage micro-column technique. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Electrocatalytic oxidation of salicylic acid by a cobalt hydrotalcite-like compound modified Pt electrode.

    Science.gov (United States)

    Gualandi, Isacco; Scavetta, Erika; Zappoli, Sergio; Tonelli, Domenica

    2011-03-15

    In this paper a study of the electrocatalytic oxidation of salicylic acid (SA) at a Pt electrode coated with a Co/Al hydrotalcite-like compound (Co/Al HTLC coated-Pt) film is presented. The voltammetric behaviour of the modified electrode in 0.1M NaOH shows two different redox couples: Co(II)/Co(III) and Co(III)/Co(IV). The electrocatalysis occurs at the same potential of the latter couple, showing that Co(IV) centers act as the oxidant. The CV investigation demonstrates that the process is controlled both by mass and charge transfer and that the Co(IV) centers involved in the oxidation are two for each SA molecule. The estimated value of the catalytic constant is 4×10(4) M(-1) s(-1). The determination of salicylic acid was performed both by DPV and chronoamperometry. The linearity ranges and the LOD values resulted 1×10(-5) to 5×10(-4), 5×10(-7) to 1×10(-4), 6×10(-6) and 2×10(-7) M, respectively. The Co/Al HTLC electrode has been used for SA determination in BAYER Aspirina® and the obtained results are consistent with an independent HPLC analysis. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Imidazolium Ionic Liquid Modified Graphene Oxide: As a Reinforcing Filler and Catalyst in Epoxy Resin

    Directory of Open Access Journals (Sweden)

    Qing Lyu

    2017-09-01

    Full Text Available Surface modification of graphene oxide (GO is one of the most important issues to produce high performance GO/epoxy composites. In this paper, the imidazole ionic liquid (IMD-Si was introduced onto the surface of GO sheets by a cheap and simple method, to prepare a reinforcing filler, as well as a catalyst in epoxy resin. The interlayer spacing of GO sheets was obviously increased by the intercalation of IMD-Si, which strongly facilitated the dispersibility of graphene oxide in organic solvents and epoxy matrix. The addition of 0.4 wt % imidazolium ionic liquid modified graphene oxide (IMD-Si@GO, yielded a 12% increase in flexural strength (141.3 MPa, a 26% increase in flexural modulus (4.69 GPa, and a 52% increase in impact strength (18.7 kJ/m2, compared to the neat epoxy. Additionally the IMD-Si@GO sheets could catalyze the curing reaction of epoxy resin-anhydride system significantly. Moreover, the improved thermal conductivities and thermal stabilities of epoxy composites filled with IMD-Si@GO were also demonstrated.

  2. Development of a stable cation modified graphene oxide membrane for water treatment

    Science.gov (United States)

    Yu, Wenzheng; (Yet Yu, Tong; Graham, Nigel

    2017-12-01

    Membranes prepared from layers of graphene oxide (GO) offer substantial advantages over conventional materials for water treatment (e.g. greater flux), but the stability of GO membranes in water has not been achieved until now. In this study the behavior of GO membranes prepared with different quantities and species of cations has been investigated to establish the feasibility of their application in water treatment. A range of cation-modified GO membranes were prepared and exposed to aqueous solutions containing specific chemical constituents. In pure water, unmodified and Na-modified GO membranes were highly unstable, while GO membranes modified with multivalent cations were stable provided there were sufficient quantities of cations present; their relative capability to achieve GO stability was as follows: Al3+  >  Ca2+  >  Mg2+  >  Na+. It is believed that the mechanism of cross-linking, and membrane stability, is via metal-carboxylate chelates and cation-graphite surface interactions (cation-π interaction), and that the latter appears to increase with increasing cation valency. The instability of cation (Ca or Al)-modified GO membranes by NaCl solutions during permeation occurred as Na+ exchanged with the incorporated multivalent cations, but a high content of Al3+ in the GO membrane impeded Al3+/Na+ exchange and thus retained membrane stability. In solutions containing biopolymers representative of surface waters or seawater (protein and polysaccharide solutions), Ca-GO membranes (even with high Ca2+ content) were not stable, while Al-GO membranes were stable if the Al3+ content was sufficiently high; Al-formed membranes also had a greater flux than Ca-GO membranes.

  3. Adsorption of nickel ions by oleate-modified magnetic iron oxide nanoparticles.

    Science.gov (United States)

    Magnet, Cécilia; Lomenech, Claire; Hurel, Charlotte; Reilhac, Pierre; Giulieri, Françoise; Chaze, Anne-Marie; Persello, Jacques; Kuzhir, Pavel

    2017-03-01

    In this work, magnetic nanoparticles of iron oxide (MNPs) were synthesized, and then the surface was recovered with an oleate double layer in order to investigate the ability of this material to adsorb nickel ions. First, the solution chemistry of oleate ions was investigated in order to determine the critical micellar concentration (CMC) value and the arrangements of ions above the CMC. Then, the synthesized oleate-modified MNP was characterized (TEM, DLS, XRD, FTIR, zeta potential, magnetometry). Finally, adsorption experiments were carried out as a function of pH and as a function of nickel concentration in 0.1 g L -1 suspensions of oleate-modified MNP. The results show that CMC of oleate ranges from 1 to 2.5∙10 -3  mol L -1 . Above CMC, arrangement of oleate ions as droplets, vesicles, or micelles depends on pH and influences the average size and solution absorbance. Potentiometric titrations allowed determining a pKa value of 7.8 for sodium oleate. The high stability in aqueous suspensions and characterization of oleate-modified MNP confirm that oleate ions are arranged as a bilayer coating at the surface of MNP. Retention of nickel was found to be highly dependent on pH, with a maximum adsorption (90%) beginning from pH = 7.5. The sorption isotherms were well fitted with the Langmuir model and the maximum nickel adsorption capacities were found to be 44 and 80 mg g -1 for pH = 6.8 and 7.2, respectively. The efficient removal of nickel combined with the magnetic properties of the NMP make the oleate-modified MNP an interesting water purification tool.

  4. Synthesis Mechanism of Low-Voltage Praseodymium Oxide Doped Zinc Oxide Varistor Ceramics Prepared Through Modified Citrate Gel Coating

    Directory of Open Access Journals (Sweden)

    Wan Rafizah Wan Abdullah

    2012-04-01

    Full Text Available High demands on low-voltage electronics have increased the need for zinc oxide (ZnO varistors with fast response, highly non-linear current-voltage characteristics and energy absorption capabilities at low breakdown voltage. However, trade-off between breakdown voltage and grain size poses a critical bottle-neck in the production of low-voltage varistors. The present study highlights the synthesis mechanism for obtaining praseodymium oxide (Pr6O11 based ZnO varistor ceramics having breakdown voltages of 2.8 to 13.3 V/mm through employment of direct modified citrate gel coating technique. Precursor powder and its ceramics were examined by means of TG/DTG, FTIR, XRD and FESEM analyses. The electrical properties as a function of Pr6O11 addition were analyzed on the basis of I-V characteristic measurement. The breakdown voltage could be adjusted from 0.01 to 0.06 V per grain boundary by controlling the amount of Pr6O11 from 0.2 to 0.8 mol%, without alteration of the grain size. The non-linearity coefficient, α, varied from 3.0 to 3.5 and the barrier height ranged from 0.56 to 0.64 eV. Breakdown voltage and α lowering with increasing Pr6O11 content were associated to reduction in the barrier height caused by variation in O vacancies at grain boundary.

  5. Study of NiO cathode modified by rare earth oxide additive for MCFC by electrochemical impedance spectroscopy

    International Nuclear Information System (INIS)

    Huang Bo; Chen Gang; Li Fei; Yu Qingchun; Hu Keao

    2004-01-01

    The preparation and subsequent oxidation of nickel cathodes modified by impregnation with rare earth oxide were evaluated by surface and bulk analysis. The electrochemical behaviors of rare earth oxide impregnated nickel oxide cathodes were also evaluated in a molten 62 mol% Li 2 CO 3 +38 mol% K 2 CO 3 eutectic at 650 deg. C by electrochemical impedance spectroscopy (EIS) as a function of rare earth oxide content and immersion time. The rare earth oxide-impregnated nickel cathodes show almost the similar porosity, pore size, and morphology to the reference nickel cathode. The stability tests of rare earth oxide-impregnated nickel oxide cathodes show that the rare earth oxide additive can dramatically reduce the solubility of nickel oxide in a eutectic carbonate mixture under the standard cathode gas condition. The impedance response of all cathode materials at different immersion time is characterized by the presence of depressed semicircles in the high frequency range changing over into the lines with the angles of which observed with the real axis differing 45 deg. or 90 deg. in the low frequency range. The experimental Nyquist plots can be well analyzed theoretically with a modified model based on the well-known Randles-Ershler equivalent circuit model. In the new model, the double layer capacity (C d ) is replaced by the parallel combination of C d and b/ω; therefore, this circuit is modified to be the parallel combination of (C d ), b/ω, and the charge transfer resistance (R ct ) based on the Randles-Ershler equivalent circuit, to take into consideration both the non-uniformity of electric field at the electrode/electrolyte interface owing to the roughness of electrode surface, and the variety of relaxation times with adsorbed species on the electrode surface. The impedance spectra for all cathode materials show important variations during the 200 h of immersion. The incorporation of lithium in its structure and the low dissolution of nickel oxide and rare

  6. Reactive removal of 2-chloroethyl ethyl sulfide vapors under visible light irradiation by cerium oxide modified highly porous zirconium (hydr) oxide

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, Joshua K.; Arcibar-Orozco, Javier A.; Bandosz, Teresa J., E-mail: tbandosz@ccny.cuny.edu

    2016-12-30

    Highlights: • Microporous zirconium-cerium (hydr) oxides were synthetized. • Ce presence narrowed the band gap of the materials. • The samples showed a high efficiency for removal of CEES vapors. • 1,2-Bis (ethyl thio) ethane and ethyl vinyl sulfide were the main reaction products. • 5% (Ce/Zr mol) addition of cerium oxide results in the best performing material. - Abstract: Highly porous cerium oxide modified Zr(OH){sub 4} samples were synthesized using a simple one stage urea precipitation method. The amorphicity level of zirconium hydroxide did not change upon addition of cerium oxide particles. A unique aspect of the cerium oxide-modified materials is the presence of both the oxide (CeO{sub 2}) and hydroxide (Zr(OH){sub 4}) phases resulting in a unique microporous structure of the final material. Extensive characterization using various chemical and physical methods revealed significant differences in the surface features. All synthesized materials were microporous and small additions of cerium oxide affected the surface chemistry. These samples were found as effective catalysts for a decontamination of mustard gas surrogate, 2-chloroethyl ethyl sulfide (CEES). Cerium oxide addition significantly decreased the band gap of zirconium hydroxide. Ethyl vinyl sulfide and 1,2-bis (Ethyl thio) ethane were identified as surface reaction products.

  7. Composite anion-exchangers modified with nanoparticles of hydrated oxides of multivalent metals

    Science.gov (United States)

    Maltseva, T. V.; Kolomiets, E. O.; Dzyazko, Yu. S.; Scherbakov, S.

    2018-02-01

    Organic-inorganic composite ion-exchangers based on anion exchange resins have been obtained. Particles of one-component and two-component modifier were embedded using the approach, which allows us to realize purposeful control of a size of the embedded particles. The approach is based on Ostwald-Freundlich equation, which was adapted to deposition in ion exchange matrix. The equation was obtained experimentally. Hydrated oxides of zirconium and iron were applied to modification, concentration of the reagents were varied. The embedded particles accelerate sorption, the rate of which is fitted by the model equation of chemical reactions of pseudo-second order. When sorption of arsenate ions from very diluted solution (50 µg dm-3) occurs, the composites show higher distribution coefficients comparing with the pristine resin.

  8. Electrocatalytic Reduction-oxidation of Chlorinated Phenols using a Nanostructured Pd-Fe Modified Graphene Catalyst

    International Nuclear Information System (INIS)

    Shi, Qin; Wang, Hui; Liu, Shaolei; Pang, Lei; Bian, Zhaoyong

    2015-01-01

    A Pd-Fe modified graphene (Pd-Fe/G) catalyst was prepared by the Hummers oxidation method and bimetallic co-deposition method. The catalyst was then characterized by various characterization techniques and its electrochemical property toward the electrocatalytic reduction-oxidation of chlorinated phenols was investigated by using cyclic voltammetry and differential pulse voltammetry. The results of the characterization show that the Pd-Fe/G catalyst in which the weight proportion of Pd and Fe is 1:1 has an optimal surface performance. The diameter of the Pd-Fe particles is approximately 5.2 ± 0.3 nm, with a uniform distribution on the supporting graphene. This is smaller than the Pd particles of a Pd-modified graphene (Pd/G) catalyst. The Pd-Fe/G catalyst shows a higher electrocatalytic activity than the Pd/G catalyst for reductive dechlorination when feeding with hydrogen gas. The reductive peak potentials of −0.188 V, −0.836 V and −0.956 V in the DPV curves are attributed to the dechlorination of ortho-Cl, meta-Cl, and para-Cl in 2-chlorophenol, 3-chlorophenol and 4-chlorophenol, respectively. In accordance with an analysis of the frontier orbital theory, the order of ease of dechlorination with Pd-Fe/G catalyst is 2-chlorophenol > 3-chlorophenol > 4-chlorophenol. The Pd-Fe/G catalyst has a greater activity than the Pd/G catalyst in accelerating the two-electron reduction of O 2 to H 2 O 2 , which is attributed to the higher current of the reduction peak at approximately −0.40 V when feeding with oxygen gas. Therefore, the Pd-Fe/G catalyst exhibits a higher electrocatalytic activity than the Pd/G catalyst for the reductive dechlorination and acceleration of the two-electron reduction of O 2 to H 2 O 2 .

  9. Optoelectrochemical biorecognition by optically transparent highly conductive graphene-modified fluorine-doped tin oxide substrates.

    Science.gov (United States)

    Lamberti, F; Brigo, L; Favaro, M; Luni, C; Zoso, A; Cattelan, M; Agnoli, S; Brusatin, G; Granozzi, G; Giomo, M; Elvassore, N

    2014-12-24

    Both optical and electrochemical graphene-based sensors have gone through rapid development, reaching high sensitivity at low cost and with fast response time. However, the complex validating biochemical operations, needed for their consistent use, currently limits their effective application. We propose an integration strategy for optoelectrochemical detection that overcomes previous limitations of these sensors used separately. We develop an optoelectrochemical sensor for aptamer-mediated protein detection based on few-layer graphene immobilization on selectively modified fluorine-doped tin oxide (FTO) substrates. Our results show that the electrochemical properties of graphene-modified FTO samples are suitable for complex biological detection due to the stability and inertness of the engineered electrodic interface. In addition, few-layer immobilization of graphene sheets through electrostatic linkage with an electrochemically grafted FTO surface allows obtaining an optically accessible and highly conductive platform. As a proof of concept, we used insulin as the target molecule to reveal in solution. Because of its transparency and low sampling volume (a few microliters), our sensing unit can be easily integrated in lab-on-a-chip cell culture systems for effectively monitoring subnanomolar concentrations of proteins relevant for biomedical applications.

  10. Reduced Graphene Oxide Modified the Interdigitated Chain Electrode for an Insulin Sensor

    Directory of Open Access Journals (Sweden)

    Ajay Kumar Yagati

    2016-01-01

    Full Text Available Insulin is a key regulator in glucose homeostasis and its deficiency or alternations in the human body causes various types of diabetic disorders. In this paper, we present the development of a reduced graphene oxide (rGO modified interdigitated chain electrode (ICE for direct capacitive detection of insulin. The impedance properties of rGO-ICE were characterized by equivalent circuit modeling. After an electrochemical deposition of rGO on ICE, the electrode was modified with self-assembled monolayers and insulin antibodies in order to achieve insulin binding reactions. The impedance spectra and capacitances were measured with respect to the concentrations of insulin and the capacitance change (ΔC was analyzed to quantify insulin concentration. The antibody immobilized electrode showed an increment of ΔC according to the insulin concentration in human serum ranging from 1 ng/mL to 10 µg/mL. The proposed sensor is feasible for label-free and real-time measuring of the biomarker and for point-of-care diagnosis.

  11. Reduced Graphene Oxide Modified the Interdigitated Chain Electrode for an Insulin Sensor.

    Science.gov (United States)

    Yagati, Ajay Kumar; Park, Jinsoo; Cho, Sungbo

    2016-01-15

    Insulin is a key regulator in glucose homeostasis and its deficiency or alternations in the human body causes various types of diabetic disorders. In this paper, we present the development of a reduced graphene oxide (rGO) modified interdigitated chain electrode (ICE) for direct capacitive detection of insulin. The impedance properties of rGO-ICE were characterized by equivalent circuit modeling. After an electrochemical deposition of rGO on ICE, the electrode was modified with self-assembled monolayers and insulin antibodies in order to achieve insulin binding reactions. The impedance spectra and capacitances were measured with respect to the concentrations of insulin and the capacitance change (ΔC) was analyzed to quantify insulin concentration. The antibody immobilized electrode showed an increment of ΔC according to the insulin concentration in human serum ranging from 1 ng/mL to 10 µg/mL. The proposed sensor is feasible for label-free and real-time measuring of the biomarker and for point-of-care diagnosis.

  12. Iron oxide nanoparticles modified with oleic acid: Vibrational and phase determination

    Science.gov (United States)

    Soares, Paula P.; Barcellos, Geórgia S.; Petzhold, Cesar L.; Lavayen, Vladimir

    2016-12-01

    A simple path methodology to detect the phase composition of iron oxide nanoparticles modified with oleic acid based on vibrational spectroscopy is present here and applied on three different nanoparticles prepared by co-precipitation method. Firstly, the phase composition, magnetite, maghemite, and hematite, is determined using a reference intensity ratio methodology on X-ray diffraction pattern. Also, the size of each sample was calculated by Scherrer equation. Scanning, transmission electron microscopy, microanalysis and electron diffraction show a core magnetite particles size of around 10 nm for all particles. Based on lattice vibrations, we find a concentration of around 80% of magnetite and a hematite phase lower than 5%. Whereas, the magnetite composition from X-ray diffraction shows 76%. We also investigate the metal-organic interaction and disorder degree of organic molecule conformation by infrared and Raman spectroscopy analysis. Hematite lattice vibrations show more alterations as it interacts with the organic acid. Finally, magnetic measurements at room temperature of the modified particles, suggest a superparamagnetic behavior and high saturation magnetization.

  13. Electrochemical Glucose Oxidation Using Glassy Carbon Electrodes Modified with Au-Ag Nanoparticles: Influence of Ag Content

    Directory of Open Access Journals (Sweden)

    Nancy Gabriela García-Morales

    2015-01-01

    Full Text Available This paper describes the application of glassy carbon modified electrodes bearing Aux-Agy nanoparticles to catalyze the electrochemical oxidation of glucose. In particular, the paper shows the influence of the Ag content on this oxidation process. A simple method was applied to prepare the nanoparticles, which were characterized by transmission electron microscopy, Ultraviolet-Visible spectroscopy, X-ray diffraction spectroscopy, and cyclic voltammetry. These nanoparticles were used to modify glassy carbon electrodes. The effectiveness of these electrodes for electrochemical glucose oxidation was evaluated. The modified glassy carbon electrodes are highly sensitive to glucose oxidation in alkaline media, which could be attributed to the presence of Aux-Agy nanoparticles on the electrode surface. The voltammetric results suggest that the glucose oxidation speed is controlled by the glucose diffusion to the electrode surface. These results also show that the catalytic activity of the electrodes depends on the Ag content of the nanoparticles. Best results were obtained for the Au80-Ag20 nanoparticles modified electrode. This electrode could be used for Gluconic acid (GA production.

  14. Zinc oxide nanostructure-modified textile and its application to biosensing, photocatalysis, and as antibacterial material.

    Science.gov (United States)

    Hatamie, Amir; Khan, Azam; Golabi, Mohsen; Turner, Anthony P F; Beni, Valerio; Mak, Wing Cheung; Sadollahkhani, Azar; Alnoor, Hatim; Zargar, Behrooz; Bano, Sumaira; Nur, Omer; Willander, Magnus

    2015-10-06

    Recently, one-dimensional nanostructures with different morphologies (such as nanowires, nanorods (NRs), and nanotubes) have become the focus of intensive research, because of their unique properties with potential applications. Among them, zinc oxide (ZnO) nanomaterials has been found to be highly attractive, because of the remarkable potential for applications in many different areas such as solar cells, sensors, piezoelectric devices, photodiode devices, sun screens, antireflection coatings, and photocatalysis. Here, we present an innovative approach to create a new modified textile by direct in situ growth of vertically aligned one-dimensional (1D) ZnO NRs onto textile surfaces, which can serve with potential for biosensing, photocatalysis, and antibacterial applications. ZnO NRs were grown by using a simple aqueous chemical growth method. Results from analyses such as X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed that the ZnO NRs were dispersed over the entire surface of the textile. We have demonstrated the following applications of these multifunctional textiles: (1) as a flexible working electrode for the detection of aldicarb (ALD) pesticide, (2) as a photocatalyst for the degradation of organic molecules (i.e., Methylene Blue and Congo Red), and (3) as antibacterial agents against Escherichia coli. The ZnO-based textile exhibited excellent photocatalytic and antibacterial activities, and it showed a promising sensing response. The combination of sensing, photocatalysis, and antibacterial properties provided by the ZnO NRs brings us closer to the concept of smart textiles for wearable sensing without a deodorant and antibacterial control. Perhaps the best known of the products that is available in markets for such purposes are textiles with silver nanoparticles. Our modified textile is thus providing acceptable antibacterial properties, compared to available commercial modified textiles.

  15. Preparation and Application of Water-in-Oil Emulsions Stabilized by Modified Graphene Oxide

    Directory of Open Access Journals (Sweden)

    Xiaoma Fei

    2016-08-01

    Full Text Available A series of alkyl chain modified graphene oxides (AmGO with different alkyl chain length and content was fabricated using a reducing reaction between graphene oxide (GO and alkyl amine. Then AmGO was used as a graphene-based particle emulsifier to stabilize Pickering emulsion. Compared with the emulsion stabilized by GO, which was oil-in-water type, all the emulsions stabilized by AmGO were water-in-oil type. The effects of alkyl chain length and alkyl chain content on the emulsion properties of AmGO were investigated. The emulsions stabilized by AmGO showed good stability within a wide range of pH (from pH = 1 to pH = 13 and salt concentrations (from 0.1 to 1000 mM. In addition, the application of water-in-oil emulsions stabilized by AmGO was investigated. AmGO/polyaniline nanocomposite (AmGO/PANi was prepared through an emulsion approach, and its supercapacitor performance was investigated. This research broadens the application of AmGO as a water-in-oil type emulsion stabilizer and in preparing graphene-based functional materials.

  16. Modified and improved Hummer's synthesis of graphene oxide for capacitors applications

    Directory of Open Access Journals (Sweden)

    M. Sohail

    2017-09-01

    Full Text Available In the present study, we explored whether different characteristics of graphene oxide prepared via two different routes have been modified. It was observed that samples obtained via both routes have nearly the same physico-chemical characteristics. Spectral (FT-IR and UV-vis studies showed the synthesis and optical properties of the materials respectively. Optical band gap (Eg was found to be in the range of 3.1–3.9 eV. Thermal studies demonstrated that the prepared materials exhibited stability up to 550 °C. X-ray diffraction evaluated the semi-crystalline nature of the materials with crystallite size in the range from 27–28 nm. Dielectric study showed that the materials are active at low frequency range due to interfacial polarization while at higher frequency the dipoles present in the materials show relaxation behavior. The lowest value of dielectric tan. loss (0.03–0.39 acquired by both the samples is of immense importance for capacitors. Based on the observations, graphene oxide prepared is suggested to be used a possible material in thermally stable capacitors and in composite materials.

  17. Novel KMnO4-modified iron oxide for effective arsenite removal

    International Nuclear Information System (INIS)

    Huang, Yao-Hui; Shih, Yu-Jen; Cheng, Fu-Ji

    2011-01-01

    Highlights: ► We employ the MnBT-4 adsorbent for As (III)/(V) removal in solution. ► The waste iron oxide BT-4 acts as the support to immobilize Mn using FBR reactor. ► MnBT-4 has higher arsenite adsorption as compared with BT4. ► Easy solid–liquid separation and cost effective are the merits of applying MnBT-4. - Abstract: This work demonstrates the synthesis of a novel KMnO 4 -modified form of iron oxide, MnBT-4, using a fluidized bed reactor (FBR) for the adsorptive removal of arsenic (III)/(V). Characterization by XRD, BET, and SEM indicated that the BT-4 support was poorly crystallized goethite (α-FeOOH) with a specific surface area of 229 m 2 g −1 . In FBR experiments of synthesizing MnBT-4, the Fe and Mn salts were found to have an optimal dosage ratio of less than 4, which maximized the KMnO 4 immobilization efficiency. The immobilized Mn compounds on MnBT-4 underwent an additional oxidation step of As (III), promoting arsenic adsorption. When applied MnBT-4 for As (III) removal from solution, the sorption isotherm was accurately fitted with Langmuir and Freundlich models, while the maximum adsorption capacity of 27.4 mg g −1 exceeded those of other adsorbents in the literature. Batch experimental results revealed that both raw BT-4 and MnBT-4 could take up a large amount of As (V). However, the MnBT-4 provided a substantially higher As (III) removal efficiency than BT-4.

  18. Modification of Coal Char-loaded TiO2 by Sulfonation and Alkylsilylation to Enhance Catalytic Activity in Styrene Oxidation with Hydrogen Peroxide as Oxidant

    Directory of Open Access Journals (Sweden)

    Mukhamad Nurhadi

    2017-04-01

    Full Text Available The modified coal char from low-rank coal by sulfonation, titanium impregnation and followed by alkyl silylation possesses high catalytic activity in styrene oxidation. The surface of coal char was undergone several steps as such: modification using concentrated sulfuric acid in the sulfonation process, impregnation of 500 mmol titanium(IV isopropoxide and followed by alkyl silylation of n-octadecyltriclorosilane (OTS. The catalysts were characterized by X-ray diffraction (XRD, IR spectroscopy, nitrogen adsorption, and hydrophobicity. The catalytic activity of the catalysts has been examined in the liquid phase styrene oxidation by using aqueous hydrogen peroxide as oxidant. The catalytic study showed the alkyl silylation could enhance the catalytic activity of Ti-SO3H/CC-600(2.0. High catalytic activity and reusability of the o-Ti-SO3H/CC-600(2.0 were related to the modification of local environment of titanium active sites and the enhancement the hydrophobicity of catalyst particle by alkyl silylation. Copyright © 2017 BCREC GROUP. All rights reserved Received: 24th May 2016; Revised: 11st October 2016; Accepted: 18th October 2016 How to Cite: Nurhadi, M. (2017. Modification of Coal Char-loaded TiO2 by Sulfonation and Alkylsilylation to Enhance Catalytic Activity in Styrene Oxidation with Hydrogen Peroxide as Oxidant. Bulletin of Chemical Reaction Engineering & Catalysis, 12 (1: 55-61 (doi:10.9767/bcrec.12.1.501.55-61 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.12.1.501.55-61

  19. Aging modifies daily variation of antioxidant enzymes and oxidative status in the hippocampus.

    Science.gov (United States)

    Lacoste, María Gabriela; Ponce, Ivana Tamara; Golini, Rebeca Laura; Delgado, Silvia Marcela; Anzulovich, Ana Cecilia

    2017-02-01

    Aging is a complex and multifactorial biological process that leads to the progressive deterioration of physiological systems, including the circadian system. In addition, oxidative stress has been associated with the aging of the normal brain and the development of late-onset neurodegenerative diseases. Even though, functional weakening of circadian rhythms and antioxidant function has been observed during aging, the mechanisms by which the circadian system signaling and oxidative stress are interrelated have not yet been elucidated. The objectives of this study were to evaluate the consequences of aging on the temporal organization of the antioxidant defense system and oxidative status as well as to analyze the endogenous clock activity, in the hippocampus of aged rats. Young adults (3-month-old) or older (22-month-old) male Holtzman rats were maintained under constant darkness conditions, during 15days before the sacrifice. Levels of catalase (CAT) and glutathione peroxidase (GPx) mRNA and activity, reduced glutathione (GSH), lipoperoxidation (LPO) and BMAL1 protein were analyzed in hippocampus samples isolated every 4h during a 24-h period. Locomotor activity was recorded during 20days before the experiment. Our results show that aging modifies temporal patterns of CAT and GPx expression and activity in the hippocampus in a different way. On the one hand, it abolishes the oscillating CAT expression and specific enzymatic activity while, on the other, it increases the mesor of circadian GPx activity rhythm (paged rats. Moreover, the nocturnal locomotor activity was reduced in the older animals in comparison to the young adult rats (pAging also abolished circadian rhythms of the core clock BMAL1 protein. The loss of temporal organization of the antioxidant enzymes activity, the oxidative status and the cellular clock machinery could result in a temporally altered antioxidant defense system in the aging brain. Learning about how aging affects the circadian system

  20. Effect of oxygen level on the oxidative stability of two different retail pork products stored using modified atmosphere packaging (MAP)

    DEFF Research Database (Denmark)

    Spanos, Dimitrios; Ann Tørngren, Mari; Christensen, Mette

    2016-01-01

    The characteristics and the oxidative stability of pork steaks and of pork mince were investigated during 2, 5 and 7 days of refrigerated storage using oxygen (O2) levels of 0%, 20%, 50% and 80% in modified atmosphere packaging (MAP). Steaks stored during 7 days were not affected by an increase...... in O2 concentration, as revealed by lipid and protein oxidation markers. In contrast, the mince was characterised by an altered protein profile, loss of free thiol groups and increased protein oxidation, early during storage. The oxidative stability of pork mince was improved by using intermediate (50......%) O2 MAP. The results show that fresh pork products are affected differently by the MAP O2 concentration and strongly indicate that optimisation of MAP based on the retail product type would be of considerable benefit to their oxidative stability....

  1. Effect of oxygen level on the oxidative stability of two different retail pork products stored using modified atmosphere packaging (MAP).

    Science.gov (United States)

    Spanos, Dimitrios; Tørngren, Mari Ann; Christensen, Mette; Baron, Caroline P

    2016-03-01

    The characteristics and the oxidative stability of pork steaks and of pork mince were investigated during 2, 5 and 7days of refrigerated storage using oxygen (O2) levels of 0%, 20%, 50% and 80% in modified atmosphere packaging (MAP). Steaks stored during 7days were not affected by an increase in O2 concentration, as revealed by lipid and protein oxidation markers. In contrast, the mince was characterised by an altered protein profile, loss of free thiol groups and increased protein oxidation, early during storage. The oxidative stability of pork mince was improved by using intermediate (50%) O2 MAP. The results show that fresh pork products are affected differently by the MAP O2 concentration and strongly indicate that optimisation of MAP based on the retail product type would be of considerable benefit to their oxidative stability. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Electrochemical determination of hydrochlorothiazide and folic acid in real samples using a modified graphene oxide sheet paste electrode

    Energy Technology Data Exchange (ETDEWEB)

    Beitollahi, Hadi, E-mail: h.beitollahi@yahoo.com [Environment Department, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman (Iran, Islamic Republic of); Hamzavi, Mozhdeh [Department of Chemistry, Graduate University of Advanced Technology, Kerman (Iran, Islamic Republic of); Torkzadeh-Mahani, Masoud [Biotechnology Department, Institute of Science and High Technology and Environmental Sciences, Graduate University of Advanced Technology, Kerman (Iran, Islamic Republic of)

    2015-07-01

    A new ferrocene-derivative compound, 2-chlorobenzoyl ferrocene, was synthesized and used to construct a modified graphene oxide sheet paste electrode. The electrooxidation of hydrochlorothiazide at the surface of the modified electrode was studied. Under optimized conditions, the square wave voltammetric (SWV) peak current of hydrochlorothiazide increased linearly with hydrochlorothiazide concentration in the range of 5.0 × 10{sup −8} to 2.0 × 10{sup −4} M and a detection limit of 20.0 nM was obtained for hydrochlorothiazide. The diffusion coefficient and kinetic parameters (such as electron transfer coefficient and the heterogeneous rate constant) for hydrochlorothiazide oxidation were also determined. The prepared modified electrode exhibits a very good resolution between the voltammetric peaks of hydrochlorothiazide and folic acid which makes it suitable for the detection of hydrochlorothiazide in the presence of folic acid in real samples. - Highlights: • A novel modified-graphene oxide nanosheet paste electrode has been fabricated. • This electrode reduced the oxidation potential of hydrochlorothiazide by about 315 mV. • Hydrochlorothiazide was measured in the range of 5.0 × 10{sup −8} to 2.0 × 10{sup −4} M. • The detection limit for hydrochlorothiazide was obtained at 20.0 nM. • It resolved the voltammetric waves of hydrochlorothiazide and folic acid.

  3. Electrochemical determination of hydrochlorothiazide and folic acid in real samples using a modified graphene oxide sheet paste electrode.

    Science.gov (United States)

    Beitollahi, Hadi; Hamzavi, Mozhdeh; Torkzadeh-Mahani, Masoud

    2015-01-01

    A new ferrocene-derivative compound, 2-chlorobenzoyl ferrocene, was synthesized and used to construct a modified graphene oxide sheet paste electrode. The electrooxidation of hydrochlorothiazide at the surface of the modified electrode was studied. Under optimized conditions, the square wave voltammetric (SWV) peak current of hydrochlorothiazide increased linearly with hydrochlorothiazide concentration in the range of 5.0 × 10(-8) to 2.0 × 10(-4) M and a detection limit of 20.0 nM was obtained for hydrochlorothiazide. The diffusion coefficient and kinetic parameters (such as electron transfer coefficient and the heterogeneous rate constant) for hydrochlorothiazide oxidation were also determined. The prepared modified electrode exhibits a very good resolution between the voltammetric peaks of hydrochlorothiazide and folic acid which makes it suitable for the detection of hydrochlorothiazide in the presence of folic acid in real samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Adsorption of Arsenate by Nano Scaled Activated Carbon Modified by Iron and Manganese Oxides

    Directory of Open Access Journals (Sweden)

    George P. Gallios

    2017-09-01

    Full Text Available The presence of arsenic in water supplies is a major problem for public health and still concerns large parts of population in Southeast Asia, Latin America and Europe. Removal of arsenic is usually accomplished either by coagulation with iron salts or by adsorption with iron oxides or activated alumina. However, these materials, although very efficient for arsenic, normally do not remove other undesirable constituents from waters, such as chlorine and organo-chlorine compounds, which are the results of water chlorination. Activated carbon has this affinity for organic compounds, but does not remove arsenic efficiently. Therefore, in the present study, iron modified activated carbons are investigated as alternative sorbents for the removal of arsenic(V from aqueous solutions. In addition, modified activated carbons with magnetic properties can easily be separated from the solutions. In the present study, a simple and efficient method was used for the preparation of magnetic Fe3(Mn2+O4 (M:Fe and/or Mn activated carbons. Activated carbons were impregnated with magnetic precursor solutions and then calcinated at 400 °C. The obtained carbons were characterized by X-ray diffraction (XRD, nitrogen adsorption isotherms, scanning electron microscopy (SEM, vibrating sample magnetometer (VSM, Fourier Transform Infrared Spectrometry (FTIR and X-ray photoelectron spectroscopy (XPS measurements. Their adsorption performance for As(V was evaluated. The iron impregnation presented an increase in As(V maximum adsorption capacity (Qmax from about 4 mg g−1 for the raw carbon to 11.05 mg g−1, while Mn incorporation further increased the adsorption capacity at 19.35 mg g−1.

  5. Hyaluronan-modified superparamagnetic iron oxide nanoparticles for bimodal breast cancer imaging and photothermal therapy

    Directory of Open Access Journals (Sweden)

    Yang R

    2016-12-01

    Full Text Available Rui-Meng Yang,1,* Chao-Ping Fu,2,* Jin-Zhi Fang,1 Xiang-Dong Xu,1 Xin-Hua Wei,1 Wen-Jie Tang,1 Xin-Qing Jiang,1 Li-Ming Zhang2 1Department of Radiology, Guangzhou First People’s Hospital, Guangzhou Medical University, 2School of Materials Science and Engineering, School of Chemistry, Sun Yat-sen University, Guangzhou, China *These authors contributed equally to this work Abstract: Theranostic nanoparticles with both imaging and therapeutic abilities are highly promising in successful diagnosis and treatment of the most devastating cancers. In this study, the dual-modal imaging and photothermal effect of hyaluronan (HA-modified superparamagnetic iron oxide nanoparticles (HA-SPIONs, which was developed in a previous study, were investigated for CD44 HA receptor-overexpressing breast cancer in both in vitro and in vivo experiments. Heat is found to be rapidly generated by near-infrared laser range irradiation of HA-SPIONs. When incubated with CD44 HA receptor-overexpressing MDA-MB-231 cells in vitro, HA-SPIONs exhibited significant specific cellular uptake and specific accumulation confirmed by Prussian blue staining. The in vitro and in vivo results of magnetic resonance imaging and photothermal ablation demonstrated that HA-SPIONs exhibited significant negative contrast enhancement on T2-weighted magnetic resonance imaging and photothermal effect targeted CD44 HA receptor-overexpressing breast cancer. All these results indicated that HA-SPIONs have great potential for effective diagnosis and treatment of cancer. Keywords: iron oxide nanoparticles, surface functionalization, bioactive glycosaminoglycan, magnetic resonance imaging, cellular uptake, breast carcinoma

  6. Ecofriendly Fabrication of Modified Graphene Oxide Latex Nanocomposites with High Oxygen Barrier Performance.

    Science.gov (United States)

    Guan, Yidan; Meyers, Kevin P; Mendon, Sharathkumar K; Hao, Guangjie; Douglas, Jessica R; Trigwell, Steve; Nazarenko, Sergei I; Patton, Derek L; Rawlins, James W

    2016-12-07

    Large-scale industrial applications of barrier films and coatings that prevent permeation of degradative gases and moisture call for the development of cost-efficient and ecofriendly polymer nanocomposites. Herein, we report the facile fabrication of latex nanocomposites (LNCs) by incorporating surface-modified graphene oxide (mGO) at various loadings (0.025-1.2 wt %) into a styrene-acrylic latex using water as the processing solvent. LNCs fabricated with mGO exhibited significant reductions (up to 67%) in water vapor sorption, resulting in greater environmental stability when compared to LNCs fabricated with equivalent loading of hydrophilic, unmodified GO. The assembly and coalescence of the exfoliated latex/mGO dispersions during the film formation process produced highly dispersed and well-ordered mGO domains with high aspect ratios, where alignment and overlap of the mGO domains improved with increasing mGO content. The addition of only 0.7 vol % (1.2 wt %) mGO led to an 84% decrease (relative to the neat polymer latex film) in oxygen permeability of the LNC films, an excellent barrier performance attributed to the observed LNC film morphologies. This work enables ecofriendly development of mechanically flexible mGO/LNC films with superior barrier properties for many industrial applications including protective coatings, food packaging, and biomedical products.

  7. Is Physical Activity Able to Modify Oxidative Damage in Cardiovascular Aging?

    Directory of Open Access Journals (Sweden)

    Graziamaria Corbi

    2012-01-01

    Full Text Available Aging is a multifactorial process resulting in damage of molecules, cells, and tissues. It has been demonstrated that the expression and activity of antioxidant systems (SOD, HSPs are modified in aging, with reduced cell ability to counteract the oxidant molecules, and consequent weak resistance to ROS accumulation. An important mechanism involved is represented by sirtuins, the activity of which is reduced by aging. Physical activity increases the expression and the activity of antioxidant enzymes, with consequent reduction of ROS. Positive effects of physical exercise in terms of antioxidant activity could be ascribable to a greater expression and activity of SOD enzymes, HSPs and SIRT1 activity. The antioxidant effects could increase, decrease, or not change in relation to the exercise protocol. Therefore, some authors by using a new approach based on the in vivo/vitro technique demonstrated that the highest survival and proliferation and the lowest senescence were obtained by performing an aerobic training. Therefore, the in vivo/vitro technique described could represent a good tool to better understand how the exercise training mediates its effects on aging-related diseases, as elderly with heart failure that represents a special population in which the exercise plays an important role in the improvement of cardiovascular function, quality of life, and survival.

  8. Hyaluronan-modified superparamagnetic iron oxide nanoparticles for bimodal breast cancer imaging and photothermal therapy.

    Science.gov (United States)

    Yang, Rui-Meng; Fu, Chao-Ping; Fang, Jin-Zhi; Xu, Xiang-Dong; Wei, Xin-Hua; Tang, Wen-Jie; Jiang, Xin-Qing; Zhang, Li-Ming

    2017-01-01

    Theranostic nanoparticles with both imaging and therapeutic abilities are highly promising in successful diagnosis and treatment of the most devastating cancers. In this study, the dual-modal imaging and photothermal effect of hyaluronan (HA)-modified superparamagnetic iron oxide nanoparticles (HA-SPIONs), which was developed in a previous study, were investigated for CD44 HA receptor-overexpressing breast cancer in both in vitro and in vivo experiments. Heat is found to be rapidly generated by near-infrared laser range irradiation of HA-SPIONs. When incubated with CD44 HA receptor-overexpressing MDA-MB-231 cells in vitro, HA-SPIONs exhibited significant specific cellular uptake and specific accumulation confirmed by Prussian blue staining. The in vitro and in vivo results of magnetic resonance imaging and photothermal ablation demonstrated that HA-SPIONs exhibited significant negative contrast enhancement on T 2 -weighted magnetic resonance imaging and photothermal effect targeted CD44 HA receptor-overexpressing breast cancer. All these results indicated that HA-SPIONs have great potential for effective diagnosis and treatment of cancer.

  9. Effect of Graphene-Graphene Oxide Modified Anode on the Performance of Microbial Fuel Cell

    Science.gov (United States)

    Yang, Na; Ren, Yueping; Li, Xiufen; Wang, Xinhua

    2016-01-01

    The inferior hydrophilicity of graphene is an adverse factor to the performance of the graphene modified anodes (G anodes) in microbial fuel cells (MFCs). In this paper, different amounts of hydrophilic graphene oxide (GO) were doped into the modification layers to elevate the hydrophilicity of the G anodes so as to further improve their performance. Increasing the GO doped ratio from 0.15 mg·mg−1 to 0.2 mg·mg−1 and 0.25 mg·mg−1, the static water contact angle (θc) of the G-GO anodes decreased from 74.2 ± 0.52° to 64.6 ± 2.75° and 41.7 ± 3.69°, respectively. The G-GO0.2 anode with GO doped ratio of 0.2 mg·mg−1 exhibited the optimal performance and the maximum power density (Pmax) of the corresponding MFC was 1100.18 mW·m−2, 1.51 times higher than that of the MFC with the G anode. PMID:28335302

  10. Protein determination using graphene oxide-aptamer modified gold nanoparticles in combination with Tween 80.

    Science.gov (United States)

    Gao, Li; Li, Qin; Li, Raoqi; Deng, Zebin; Brady, Brendan; Xia, Ni; Chen, Guimin; Zhou, Yang; Xia, Hengchuan; Chen, Keping; Shi, Haixia

    2016-10-19

    Recently, graphene oxide (GO) has shown superiority for disease detection arising from its unique physical and chemical properties. However, proteins adsorbed on the surface of GO prevent sensitivity improvement in fluorescence-based detection methods. In this paper, a label-free method based on aptamer modified gold nanoparticles (GNPs) combined with Tween 80 was shown to solve this problem using the detection of thrombin as an example. An aptamer was designed and bound to thrombin by changing its conformation. Tween 80 was used for rapid and reproducible synthesis of stable DNA-functionalized GNPs and prevented the thrombin from nonspecific binding to GO. Thrombin was detected with a limit of 0.68 pM by taking advantage of the efficient cross-linking effect of aptamer-GNPs to GO. The sensor was validated by determining thrombin concentration in human blood serum samples. The results indicate that this method has promising analytical application in medical diagnostic. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Applicability and Optimal Parameters Analysis for Chemical Phosphorus Removal in a Modified Carrousel Oxidation Ditch

    Directory of Open Access Journals (Sweden)

    Tao Zhang

    2017-07-01

    Full Text Available In order to confine the aqua-eutrophication problem arising from phosphorus pollution, many municipal wastewater treatment plants have to improve their executive drainage standard for total phosphorus (TP. In this study, a municipal wastewater treatment plant employing modified Carrousel oxidation ditch as main biological treatment unit was selected as a representative case. Technical necessity for adding a chemically enhanced phosphorus removal unit was analysed, and process feasibility was verified by batch and continuous experiments as well. The study results were summarized as follows. Because the organic carbon source in influent wastewater is not enough, it is impossible to satisfy the national drainage standard of TP by individual biological phosphorus removal processes, therefore, aided chemical phosphorus removal is essential. The polymeric aluminium chloride (PAC is preferable to be used as precipitant for phosphorus removal. The molar ratio of agent dosage to TP removal is preferable to be about 2.0. Under these conditions, the effluent TP concentration can be lower than 1.0 mg l−1.

  12. Silver Modified Degussa P25 for the Photocatalytic Removal of Nitric Oxide

    Directory of Open Access Journals (Sweden)

    Neil Bowering

    2007-01-01

    Full Text Available A study of the photocatalytic behaviour of silver modified titanium dioxide materials for the decomposition and reduction of nitric oxide (NO gas has been carried out. The effects of silver loading, calcination temperature, and reaction conditions have been investigated. Prepared photocatalysts were characterised using XRD, TEM, and XPS. A continuous flow reactor was used to determine the photocatalytic activity and selectivity of NO decomposition in the absence of oxygen as well as NO reduction using CO as the reducing agent, over the prepared photocatalysts. XRD and TEM analysis of the photocatalysts showed that crystalline silver nitrate particles were present on the titanium dioxide surface after calcination at temperatures of up to 200∘C. The silver nitrate particles are thermally decomposed to form metallic silver clusters at higher temperatures. XPS analysis of the photocatalysts showed that for each of the temperatures used, both Ag+ and Ag0 were present and that the Ag0/Ag+ ratio increased with increasing calcination temperature. The presence of metallic silver species on the TiO2 surface dramatically increased the selectivity for N2 formation of both decomposition and reduction reactions. When CO was present in the reaction gas, selectivities of over 90% were observed for all the Ag-TiO2 photocatalysts that had been calcined at temperatures above 200∘C. Unfortunately these high selectivities were at the expense of photocatalytic activity, with lower NO conversion rates than those achieved over unmodified TiO2 photocatalysts.

  13. Is physical activity able to modify oxidative damage in cardiovascular aging?

    Science.gov (United States)

    Corbi, Graziamaria; Conti, Valeria; Russomanno, Giusy; Rengo, Giuseppe; Vitulli, Piergiusto; Ciccarelli, Anna Linda; Filippelli, Amelia; Ferrara, Nicola

    2012-01-01

    Aging is a multifactorial process resulting in damage of molecules, cells, and tissues. It has been demonstrated that the expression and activity of antioxidant systems (SOD, HSPs) are modified in aging, with reduced cell ability to counteract the oxidant molecules, and consequent weak resistance to ROS accumulation. An important mechanism involved is represented by sirtuins, the activity of which is reduced by aging. Physical activity increases the expression and the activity of antioxidant enzymes, with consequent reduction of ROS. Positive effects of physical exercise in terms of antioxidant activity could be ascribable to a greater expression and activity of SOD enzymes, HSPs and SIRT1 activity. The antioxidant effects could increase, decrease, or not change in relation to the exercise protocol. Therefore, some authors by using a new approach based on the in vivo/vitro technique demonstrated that the highest survival and proliferation and the lowest senescence were obtained by performing an aerobic training. Therefore, the in vivo/vitro technique described could represent a good tool to better understand how the exercise training mediates its effects on aging-related diseases, as elderly with heart failure that represents a special population in which the exercise plays an important role in the improvement of cardiovascular function, quality of life, and survival.

  14. Solution deposited and modified iron oxide for enhanced solar water splitting

    Science.gov (United States)

    Abel, Anthony J.

    Growing worldwide energy demand coupled with an increasing awareness of anthropogenic climate change has driven research into carbon-neutral and solar-derived energy sources. One attractive strategy is the storage of solar energy in the bonds of H2 formed by photoelectrochemical (PEC) water splitting. Hematite, an iron oxide, has been widely investigated as a candidate material for PEC water splitting due to its stability, non-toxicity, earth abundance and consequent low cost, and a theoretical 15% solar-to-hydrogen conversion efficiency. However, poor electrical properties and slow rates of the water oxidation reaction have limited its potential as an economical water splitting catalyst. Additionally, the most efficient hematite-based devices are fabricated via expensive, vacuum-phase techniques, limiting scalability to broad integration into the energy supply. In this thesis, I develop a new, solution-based deposition method for high quality, planar hematite thin films using successive ionic layer adsorption and reaction (SILAR). The constant geometry and tight control over layer thickness possible with SILAR makes these films ideal model systems to understand the two key steps of PEC water oxidation: charge separation and interfacial hole transfer. In Chapter 3, I report on facile annealing treatments to dope hematite with Ti and Sn, and I show that these impurity atoms at the hematite/electrolyte interface increase hole transfer efficiency from nearly 0 to above 60%. However, charge separation remains below 15% with these dopants incorporated via solid state diffusion, mainly due to low hole mobility. To overcome this associated small transport length, extremely thin hematite coatings were deposited on Sb:SnO2 monolayer inverse opal scaffolds. With this modified substrate, photocurrent increased proportionately to the surface area of the scaffold. While Chapter 3 discusses incorporation of dopants via solid state diffusion, Chapter 4 examines methods to

  15. Physicochemical, structural and thermal properties of oxidized, acetylated and dual-modified common bean (Phaseolus vulgaris L. starch

    Directory of Open Access Journals (Sweden)

    José Pedro WOJEICCHOWSKI

    2018-03-01

    Full Text Available Abstract Common beans are rich in protein and complex carbohydrates that are valuable for the human diet. Starch is the most abundant individual component; however, in its native form it has limited applications and modifications are necessary to overcome technological restrictions. The aim of this study was to evaluate the influence of oxidation, acetylation and dual-modification (oxidation-acetylation on the physicochemical, structural and thermal properties of common bean starch. The degree of substitution of the acetylated starches was compatible with food use. Fourier transform infrared spectra confirmed the acetylation of the bean starch, with a peak at 1,735cm-1. The granules of the bean starch were oval to spherical in shape, with no differences between the native and modified samples. Typical C-type diffraction of legume starches was found. The modified samples showed a reduced relative crystallinity and lower enthalpy change of gelatinization. The oxidized starch showed the highest peak viscosity, hardness, and gel adhesiveness due to the presence of functional groups. An increase in solubility and swelling power was observed, and the oxidized-acetylated starch presented the highest values. The properties of the modified bean starches made them suitable for application in breaded/battered foods, mainly due to improved textural attributes.

  16. Water treatment with exceptional virus inactivation using activated carbon modified with silver (Ag) and copper oxide (CuO) nanoparticles.

    Science.gov (United States)

    Shimabuku, Quelen Letícia; Arakawa, Flávia Sayuri; Fernandes Silva, Marcela; Ferri Coldebella, Priscila; Ueda-Nakamura, Tânia; Fagundes-Klen, Márcia Regina; Bergamasco, Rosangela

    2017-08-01

    Continuous flow experiments (450 mL min -1 ) were performed in household filter in order to investigate the removal and/or inactivation of T4 bacteriophage, using granular activated carbon (GAC) modified with silver and/or copper oxide nanoparticles at different concentrations. GAC and modified GAC were characterized by X-ray diffractometry, specific surface area, pore size and volume, pore average diameter, scanning electron microscopy, transmission electron microscopy, zeta potential and atomic absorption spectroscopy. The antiviral activity of the produced porous media was evaluated by passing suspensions of T4 bacteriophage (∼10 5  UFP/mL) through filters. The filtered water was analyzed for the presence of the bacteriophage and the release of silver and copper oxide. The porous media containing silver and copper oxide nanoparticles showed high inactivation capacity, even reaching reductions higher than 3 log. GAC6 (GAC/Ag0.5%Cu1.0%) was effective in the bacteriophage inactivation, reaching 5.53 log reduction. The levels of silver and copper released in filtered water were below the recommended limits (100 ppb for silver and 1000 ppb for copper) in drinking water. From this study, it is possible to conclude that activated carbon modified with silver and copper oxide nanoparticles can be used as a filter for virus removal in the treatment of drinking water.

  17. Enhanced Electrochemical Oxidation of p-Nitrophenol Using Single-Walled Carbon Nanotubes/Silver Nanowires Hybrids Modified Electrodes.

    Science.gov (United States)

    Jiang, Yunfang; Liu, Xinghua; Li, Jing; Zhou, Lei; Yang, Xiaoying; Huang, Yi

    2015-08-01

    The electrochemical oxidation of p-nitrophenol (p-Np) has been studied on glassy carbon electrode modified with the single-walled carbon nanotubes/silver nanowires hybrids (SWNTs-Ag) by using cyclic and differential pulse voltammetry. p-Np is irreversibly oxidized at +0.88 V (vs. the Ag/AgCl) in PBS solutions of pH 7.4. The modified electrodes display the detection sensitivity of 0.0212 µA/µM with an unusually wide linear response of 5-1700 µM (R2 = 0.998) and the detection limit of 1 µM. The current response of SWNTs-Ag modified electrode to p-Np is better than that of SWNTs or Ag nanowires modified electrode under the same concentration. Combining the adsorption ability of SWNTs and the conductivity of SWNTs and Ag nanowires, the detection performance of SWNTs-Ag modified electrode to p-Np was greatly improved.

  18. A modified anode/electrolyte structure for a solid oxide electrochemical cell and a method for making said structure

    DEFF Research Database (Denmark)

    2013-01-01

    A novel modified anode/electrolyte structure for a solid oxide electrochemical cell is an assembly comprising (a) an anode consisting of a backbone of electronically conductive perovskite oxides selected from the group of doped strontium titanates and mixtures thereof, (b) a scandia and yttria...... treatments resulted in a distribution of the metallic and/or ceramic interlayers in the electrolyte/anode backbone junction taking place. The structure is prepared by (a) depositing a ceramic interlayer onto one side of the electrolyte, (b) optionally applying a metallic interlayer thereon, (c) repeating...

  19. Lipid oxidation and color changes of goose meat stored under vacuum and modified atmosphere conditions.

    Science.gov (United States)

    Orkusz, A; Haraf, G; Okruszek, A; Werenska-Sudnik, M

    2017-03-01

    The objective of the work was to investigate the color and lipid oxidation changes of goose breast meat packaged in vacuum and modified atmosphere (MA) conditions consisting of 80% O2, 20% CO2, and stored in refrigerated conditions at 4°C. Color stability was monitored by determining total heme pigments concentration; relative concentration of myoglobin, oxymyoglobin, and metmyoglobin; parameters of color L*, a*, b*, and sensory evaluation of the surface color. Lipid stability was measured by determining thiobarbituric acid reactive substances (TBARS). The samples were examined in 24 h after slaughter (unpacked muscles) and on d 4, 7, 9, 11 of storage (muscles packed in vacuum and in MA). Through the time of storage, samples packed in MA had higher TBARS values in comparison to the meat packed in vacuum. For samples packed in two types of atmospheres, the total pigments concentration decreased gradually within 11 d of storage. It was observed that relative metmyoglobin concentration increased whereas relative oxymyoglobin concentration decreased in total heme pigments in the MA stored muscle. The relative concentration of all three myoglobin forms sample packed in vacuum remained unchanged. The color parameters (L*, a*, b*) did not change for 11 d of storage for the vacuum packed meat. The value of the color parameter a* decreased and the value of the color parameters L* and b* increased in the samples packaged in MA. The data prove that if you store goose meat in MA (consisting of 80% O2, 20% CO2) or vacuum, the unchanged surface color is preserved for 9 and 11 day, respectively.Vacuum appears to be a better method as regards the maintaining of lipid stability in goose meat. © 2016 Poultry Science Association Inc.

  20. Performance of diatomite/iron oxide modified nonwoven membrane used in membrane bioreactor process for wastewater reclamation.

    Science.gov (United States)

    He, Yueling; Zhang, Wenqi; Rao, Pinhua; Jin, Peng

    2014-01-01

    This study describes an approach for surface modification of a nonwoven membrane by diatomite/iron oxide to examine its filterability. Analysis results showed that nonwoven hydrophilicity is enhanced. Static contact angle decreases dramatically from 122.66° to 39.33°. Scanning electron micrograph images show that diatomite/iron oxide is attached on nonwoven fiber. X-ray diffraction analysis further proves that the compound is mostly magnetite. Fourier transformed infrared spectra results reveal that two new absorption peaks might be attributed to Si-O and Fe-O, respectively. Modified and original membranes were used in double nonwoven membrane bioreactors (MBRs) for synthetic wastewater treatment. High critical flux, long filtration time, slow trans-membrane pressure rise and stable sludge volume index confirmed the advantages of modified nonwoven. Comparing with original nonwoven, similar effluent qualities are achieved, meeting the requirements for wastewater reclamation.

  1. Synthesis of Ru nanoparticles confined in magnesium oxide-modified mesoporous alumina and their enhanced catalytic performance during ammonia decomposition

    KAUST Repository

    Tan, Hua

    2012-09-01

    In this work, Ru nanoparticles confined in the channels of ordered mesoporous alumina (MA) and magnesium oxide-modified ordered MA are prepared for the first time via a two-solvent technique, combined with the amorphous citrate route. Structural characterizations reveal that uniform 2-3 nm Ru nanoparticles are highly dispersed in the blockage-free channels of mesoporous supports. The Ru nanoparticles confined in MA modified with 20% molar ratio magnesium oxide exhibited a high catalytic activity and stability during ammonia decomposition due to the optimized particle size, basic support, lack of chlorine, and confined space provided by the channels of the mesoporous supports. © 2012 Elsevier B.V. All rights reserved.

  2. Modified fly ash from municipal solid waste incineration as catalyst support for Mn-Ce composite oxides

    Science.gov (United States)

    Chen, Xiongbo; Liu, Ying; Yang, Ying; Ren, Tingyan; Pan, Lang; Fang, Ping; Chen, Dingsheng; Cen, Chaoping

    2017-08-01

    Fly ash from municipal solid waste incineration was modified by hydrothermal treatment and used as catalyst support for Mn-Ce composite oxides. The prepared catalyst showed good activity for the selective catalytic reduction (SCR) of NO by NH3. A NO conversion of 93% could be achieved at 300 °C under a GHSV of 32857 h-1. With the help of characterizations including XRD, BET, SEM, TEM, XPS and TPR, it was found that hydrothermal treatment brought a large surface area and abundant mesoporous to the modified fly ash, and Mn-Ce composite oxides were highly dispersed on the surface of the support. These physical and chemical properties were the intrinsic reasons for the good SCR activity. This work transformed fly ash into high value-added products, providing a new approach to the resource utilization and pollution control of fly ash.

  3. Determination of 8-Hydroxydeoxyguanosine: A potential biomarker of oxidative stress, using carbon-allotropic nanomaterials modified glassy carbon sensor.

    Science.gov (United States)

    Rosy; Goyal, Rajendra N

    2016-12-01

    A voltammetric sensor for the determination of 8-Hydroxydeoxyguanosine (8-OHdG); an important, sensitive and integral biomarker of oxidative stress and related pathological conditions like carcinogenesis, renal disorders, mental retardations, diabetes etc. has been fabricated. The synergistic behavior of two allotropic forms of carbon, which are electrochemically reduced graphene oxide (ErGO) and multiwalled carbon nanotubes (MWCNTs), has been exploited for the surface modification. The resulting modified surface has been characterized using Field Emission Scanning Electron Microscopy, X-ray diffraction, Electrochemical Impedance Spectroscopy and voltammetric behavior. The fabricated sensor exhibited excellent electrocatalytic effect towards oxidation of 8-OHdG and also showed substantial increment in sensitivity. The modified sensor showed a sensitivity of 0.1965µA/µM in the linear range of 3-75µM, whereas, a slope of 0.0046µA/µM was obtained for unmodified GCE. A limit of detection as low as 35nM has been obtained using the glassy carbon surface modified sensor. The proposed method was also successfully applied for the quantification of 8-OHdG in the presence of common interfering biomolecules like ascorbic acid, uric acid, xanthine, hypoxanthine etc. and also in human urine samples. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Blue shift in absorption edge of polycrystalline zinc oxide modified by nanoparticles before and after irradiation exposure

    Science.gov (United States)

    Mikhailov, M. M.; Neshchimenko, V. V.; Li, C.; Vlasov, V. A.

    2018-03-01

    The effect on band gap (Eg) and crystal structure of ZnO modified by Al2O3, ZrO2, SiO2, CeO2, TiO2 and Y2O3 nanoparticles at concentrations less than 30 wt% has been investigated. Established that change of Eg reach to 0.03 eV and determined by charge of cations and their radius, as well as the concentration of the nanoparticles. Lattice parameters changes at modifying by nanoparticles with a smaller and larger radius of cations than the ion Zn2+. Influence of 100 keV protons irradiation result in blue shift in absorption edge of polycrystalline zinc oxide modified by Al2O3, ZrO2, SiO2, CeO2, TiO2 and Y2O3 nanoparticles.

  5. Study Structure and Properties of Nanocomposite Material Based on Unsaturated Polyester with Clay Modified by Poly(ethylene oxide

    Directory of Open Access Journals (Sweden)

    Tran Duy Thanh

    2012-01-01

    Full Text Available In recent years, polymer clay nanocomposites have been attracting considerable interests in polymers science because of their advantages. There are many scientists who researched about this kind of material and demonstrated that when polymer matrix was added to little weight of clay, properties were enhanced considerably. Because clay is a hydrophilic substance so it is difficult to use as filler in polymer matrix having hydrophobic nature, so clay needs to be modified to become compatible with polymer. In this study, poly(ethylene oxide was used as a new modifier for clay to replace some traditional ionic surfactants such as primary, secondary, tertiary, and quaternary alkyl ammonium or alkylphosphonium cations having the following disadvantages: disintegrate at high temperature, catalyze polymer degradation, and make nanoproducts colorific, and so forth. In order to evaluate modifying effect of poly(ethylene oxide, modified clay products were characterize d by X-ray spectrum. Then organoclay was used to prepare nanocomposite based on unsaturated polyester. Morphology and properties of nanocomposites were measure d by X-ray diffraction, transmission electron microscopy, tensile strength, and thermal stability. The results showed that clay galleries changed to intercalated state in the nanocomposites. Properties of nanocomposites were improved a lot when the loading of the organoclay was used at 1 phr.

  6. High-Efficiency Palladium Nanoparticles Supported on Hydroxypropyl-β-Cyclodextrin Modified Fullerene [60] for Ethanol Oxidation

    International Nuclear Information System (INIS)

    Zhang, Qing; Bai, Zhengyu; Shi, Min; Yang, Lin; Qiao, Jinli; Jiang, Kai

    2015-01-01

    Highlights: • C 60 support provides new ways to develop catalyst materials for its distorted structure. • Pd nanoparticles with uniform size and high dispersion have been successfully assembled on HP-β-CD-C 60 in aqueous solution. • Pd/HP-β-CD-C 60 shows very promising catalytic activity for ethanol oxidation. - Abstract: In this paper, Palladium nanoparticles with uniform size and high dispersion have been successfully assembled on hydroxypropyl-β-Cyclodextrin (HP-β-CD) modified C 60 (abbreviated as HP-β-CD-C 60 ) via a sodium borohydride reduction process. According to the transmission electron microscopy (TEM) measurements, the average particle size of the as-prepared Pd nanoparticles dispersed on HP-β-CD modified C 60 is 2.7 nm. Electrochemical studies reveal that the Pd/HP-β-CD-C 60 modified electrode shows a significantly high electrocatalytic activity, much more negative onset potentials and better stability than electrodes modified by other electrocatalysts for ethanol oxidation, which indicates that it is a better potential candidate for application in a direct ethanol fuel cell (DEFC)

  7. Electrochemical behavior of ruthenium-hexacyanoferrate modified glassy carbon electrode and catalytic activity towards ethanol electro oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Wendell M.; Marques, Aldalea L.B., E-mail: aldalea.ufma@hotmail.com [Universidade Federal do Maranhao (UFMA), Sao Luis, MA (Brazil). Departamento de Quimica Tecnologica; Cardoso, William S.; Marques, Edmar P.; Bezerra, Cicero W.B. [Universidade Federal do Maranhao (UFMA), Sao Luis, MA (Brazil). Departamento de Qumica; Ferreira, Antonio Ap. P. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Araraquara, SP (Brazil). Instituto de Quimica; Song, Chaojie; Zhang, Jiujun [Energy, Mining and Environment Portfolio, National Research Council of Canada, Vancouver, BC (Canada)

    2013-04-15

    Ruthenium-based hexacyanoferrate (RuHCF) thin film modified glassy carbon electrode was prepared by drop evaporation method. The RuHCF modified electrode exhibited four redox couples in strong acidic solution (pH 1.5) attributed to Fe(CN){sub 6}{sup 3-} ion and three ruthenium forms (Ru(II), Ru(III) and Ru(IV)), characteristic of ruthenium oxide compounds. The modified electrode displayed excellent electrocatalytic activity towards ethanol oxidation in the potential region where electrochemical processes Ru(III)-O-Ru(IV) and Ru(IV)-O-Ru(VI) occur. Impedance spectroscopy data indicated that the charge transfer resistance decreased with the increase of the applied potential and ethanol concentration, indicating the use of the RuHCF modified electrode as an ethanol sensor. Under optimized conditions, the sensor responded linearly and rapidly to ethanol concentration between 0.03 and 0.4 mol L{sup -1} with a limit of detection of 0.76 mmol L{sup -1}, suggesting an adequate sensitivity in ethanol analyses. (author)

  8. Silica Fume Functionalized With Amine-Based Additives as a Modifier to Enhance Asphalt Resistance to Oxidation

    Science.gov (United States)

    Abutalib, Nader Turki

    This dissertation investigates the practical feasibility of functionalizing silica fume particles with the amine groups in Bio-binder and pure APTES chemical to disperse silica fume in asphalt binder matrix to produce silica-fume-modified binder (SFMB). Dispersed silica fume was then introduced to asphalt to reduce oxidative aging. It has been widely reported that asphalt binder oxidation is one of the phenomena that reduces the service life of asphalt pavement by negatively affecting its rheological properties. This in turn can lead to a more brittle pavement, which is more prone to cracks due to thermal stress and traffic loading. It has been shown that the introduction of 4% silica fume to asphalt can reduce asphalt oxidative aging. However, the challenge with a higher percentage of silica fume was found to be the agglomeration of nano- particles to form micro-size clusters, which can reduce the effectiveness of silica fume while making asphalt binder more susceptible to shear. Therefore, this dissertation studies the effectiveness of functionalizing the SFMB to reduce asphalt oxidative aging while alleviating the agglomeration effect. To do so, various percentages of bio-binder (BB) and bio-char (BC) were introduced to SFMB, and the rheological properties and high-temperature performance of each specimen were evaluated by measuring the rotational viscosity and complex shear modulus before and after oxidative aging. It is hypothesized that fine-graded BC and BB with nano- to micro-level particles can be used to reduce asphalt oxidation and create a new generation of low- agglomeration SFMB with higher resistance to oxidative aging. To further study the effects of functionalization on dispersion of silica fume, silica fume particles were produced with different functional groups: amine (APTES) groups and phosphonate (THPMP) groups. Agglomeration studies using a scanning electron microscope and zeta potential analysis indicate that modifying asphalt binder with

  9. Nano Copper Oxide-Modified Carbon Cloth as Cathode for a Two-Chamber Microbial Fuel Cell

    Science.gov (United States)

    Dong, Feng; Zhang, Peng; Li, Kexun; Liu, Xianhua; Zhang, Pingping

    2016-01-01

    In this work, Cu2O nanoparticles were deposited on a carbon cloth cathode using a facile electrochemical method. The morphology of the modified cathode, which was characterized by scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) tests, showed that the porosity and specific surface area of the cathode improved with longer deposition times. X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV) results showed that cupric oxide and cuprous oxide coexisted on the carbon cloth, which improved the electrochemical activity of cathode. The cathode with a deposition time of 100 s showed the best performance, with a power density twice that of bare carbon cloth. Linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) results revealed that moderate deposition of nano copper oxide on carbon cloth could dramatically reduce the charge transfer resistance, which contributed to the enhanced electrochemical performance. The mediation mechanism of copper oxide nanocatalyst was illustrated by the fact that the recycled conversion between cupric oxide and cuprous oxide accelerated the electron transfer efficiency on the cathode. PMID:28335366

  10. Electrochemical characterization of mixed matrix heterogeneous cation exchange membranes modified by simultaneous using ilmenite-co-iron oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hosseini, Sayed Mohsen; Hamidi, Alireza; Moghadassi, Abdolreza [Faculty of Engineering, Arak University, Arak (Iran, Islamic Republic of); Madaeni, Sayed Siavash [Razi University, Kermanshah (Iran, Islamic Republic of)

    2015-03-15

    Mixed matrix heterogeneous cation exchange membranes were prepared by solution casting technique. Ilmenite-co-iron oxide nanoparticle was also employed as inorganic filler additive in membrane fabrication. The effect of the used additives on membrane electrochemical properties was studied. Membrane ion exchange capacity, membrane potential, transport number and selectivity all were improved by use of FeTiO{sub 3}/Fe{sub 3}O{sub 4} nanoparticles in membrane matrix. Utilizing FeTiO{sub 3}-co-Fe{sub 3}O{sub 4} nanoparticles in the casting solution also led to increase in ionic flux obviously. The modified membranes containing FeTiO{sub 3}-co-Fe{sub 3}O{sub 4} nanoparticles showed higher transport number, selectivity and ionic flux compared to modified membrane containing ilmenite. Electrodialysis experiment in laboratory scale also showed higher cation removal for modified membrane containing FeTiO{sub 3}-co-Fe{sub 3}O{sub 4} nanoparticles compared to other modified membranes and pristine ones. Results showed that membrane areal electrical resistance declined sharply by use of FeTiO{sub 3}-co-Fe{sub 3}O{sub 4} nanoparticles in membrane matrix. Moreover, modified membrane containing ilmenite showed lower electrical resistance compared to others. Results showed that oxidative stability of membranes was decreased slightly by use of FeTiO{sub 3}/Fe{sub 3}O{sub 4} nanoparticles in membrane matrix. The results revealed that modified membranes in this study are comparable with that of other commercial ones.

  11. Electrochemical determination of serotonin in urine samples based on metal oxide nanoparticles/MWCNT on modified glassy carbon electrode

    Directory of Open Access Journals (Sweden)

    Omolola E. Fayemi

    2017-04-01

    Full Text Available The electrochemical response of serotonin on the modified electrode based on multiwalled-carbon-nanotube (MWCNT doped respectively with nickel, zinc and iron oxide nanoparticles coating on glassy carbon electrode (GCE at physiological pH 7 was determined using cyclic voltammetry (CV and square wave voltammetry (SWV. The modified GCE/MWCNT-metal oxide electrodes exhibited excellent electrocatalytic activity towards the detection of serotonin at large peak current and lower oxidation potentials compared to other electrodes investigated. The dynamic range for the serotonin determination was between 5.98 × 10−3 μM to 62.8 μM with detection limits 118, 129 and 166 nM for GCE/MWCNT-NiO, GCE/MWCNT-ZnO and GCE/MWCNT-Fe3O4 sensors respectively. GCE-MWCNT-NiO was the best electrode in terms of serotonin current response, electrode stability, resistance to fouling and limit of detection towards the analyte. The developed sensors were found to be electrochemically stable, reusable, economically effective due to their extremely low operational cost, and have demonstrated good limit of detection, sensitivity and selectivity towards serotonin determination in urine samples. Keywords: Metal oxides nanoparticles, Multiwalled carbon nanotubes, Glassy carbon electrode, Serotonin, Cyclic voltammetry, Square wave voltammetry

  12. DNA biosensors based on gold nanoparticles-modified graphene oxide for the detection of breast cancer biomarkers for early diagnosis.

    Science.gov (United States)

    Saeed, Ayman Ali; Sánchez, Josep Lluís Acero; O'Sullivan, Ciara K; Abbas, Mohammed Nooredeen

    2017-12-01

    Two different DNA (ERBB2c and CD24c) modified gold nanoparticles and graphene oxide loaded on glassy carbon electrodes were prepared for early detection of breast cancer markers by electrochemical detection of HER2. Comparative study of ERBB2c and CD24c for the detection was carried out. A "sandwich-type" detection strategy was employed in this electrochemical DNA biosensor and its response was measured by amperometric detection. The electrochemical signal enhancement achieved via gold nanoparticles and grapheme oxide system allowed for sensitive detection of the breast cancer biomarker ERBB2 and the control marker CD24. The modified graphene oxide was characterised using Raman spectroscopy, UV-visible spectroscopy, Fourier transform infrared spectroscopy transmission electron microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The various steps involved in the modification of a glassy carbon electrode with graphene oxide, gold nanoparticles and DNA probes, target and reporter probe were electrochemically characterised using cyclic voltammetry and electrochemical impedance spectroscopy. Using amperometric detection of a horse radish peroxidase label, detection limits of 0.16nM and 0.23nM were obtained with sensitivity 378nA/nM and 219nA/nM for ERBB2 andCD24 respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Development and characterization of fluorine tin oxide electrodes modified with high area porous thin films containing gold nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Quintana, Carmen, E-mail: carmen.quintana@uam.e [Dpto. Quimica Analitica y Analisis Instrumental. Facultad de Ciencias. Universidad Autonoma de Madrid. Cantoblanco. 28049-Madrid (Spain); Atienzar, Pedro; Budroni, Gerolamo [Instituto de Tecnologia Quimica de Valencia, UPV-CSIC, Universidad Politecnica de Valencia, Av. de los Naranjos s/n, 46022-Valencia (Spain); Mora, Laura; Hernandez, Lucas [Dpto. Quimica Analitica y Analisis Instrumental. Facultad de Ciencias. Universidad Autonoma de Madrid. Cantoblanco. 28049-Madrid (Spain); Garcia, Hermenegildo; Corma, Avelino [Instituto de Tecnologia Quimica de Valencia, UPV-CSIC, Universidad Politecnica de Valencia, Av. de los Naranjos s/n, 46022-Valencia (Spain)

    2010-10-29

    Different electrode materials are prepared using fluoride doped tin oxide (FTO) electrodes modified with high area porous thin films of metal oxides containing gold nanoparticles. Three different metal oxides (TiO{sub 2}, MgO and SnO{sub 2}) have been assayed to this end. The effect of the metal oxide nature and gold loading on the structure and performance of the modified electrodes was examined by Scanning Electron Microscopy, Transmission Electron Microscopy, X-Ray Diffraction (XRD), Diffuse Reflectance Spectroscopy and electrochemical techniques. XRD measurements reveal that MgO electrodes present the smallest gold nanoparticles after the sintering step however, the electrochemical response of these electrodes shows important problems of mass transport derived from the high porosity of these materials (Brunauer Emmett Teller area of 125 m{sup 2}/g). The excellent sintering properties of titania nanoparticles result in robust films attached to the FTO electrodes which allow more reliable and reproducible results from an electroanalytical point of view.

  14. Long-Term Synaptic Plasticity Emulated in Modified Graphene Oxide Electrolyte Gated IZO-Based Thin-Film Transistors.

    Science.gov (United States)

    Yang, Yi; Wen, Juan; Guo, Liqiang; Wan, Xiang; Du, Peifu; Feng, Ping; Shi, Yi; Wan, Qing

    2016-11-09

    Emulating neural behaviors at the synaptic level is of great significance for building neuromorphic computational systems and realizing artificial intelligence. Here, oxide-based electric double-layer (EDL) thin-film transistors were fabricated using 3-triethoxysilylpropylamine modified graphene oxide (KH550-GO) electrolyte as the gate dielectrics. Resulting from the EDL effect and electrochemical doping between mobile protons and the indium-zinc-oxide channel layer, long-term synaptic plasticity was emulated in our devices. Synaptic functions including long-term memory, synaptic temporal integration, and dynamic filters were successfully reproduced. In particular, spike rate-dependent plasticity (SRDP), one of the basic learning rules of long-term plasticity in the neural network where the synaptic weight changes according to the rate of presynaptic spikes, was emulated in our devices. Our results may facilitate the development of neuromorphic computational systems.

  15. Electrochemical oxidation of 4-chloro phenol over a carbon paste electrode modified with Zn Al layered double hydroxides

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez F, D.; Palomar P, M.; Licona S, T. de J.; Romero R, M. [Universidad Autonoma Metropolitana, Unidad Azcapotzalco, Departamento de Materiales, Av. San Pablo 180, Col. Reynosa-Tamaulipas, 02200 Mexico D. F. (Mexico); Valente, Jaime S., E-mail: mepp@correo.azc.uam.mx [Instituto Mexicano del Petroleo, Eje Central No. 152, 07730 Mexico D. F. (Mexico)

    2014-07-01

    A study is presented on the electrochemical oxidation of 4-chloro phenol (4cp) in aqueous solution using a bare carbon paste electrode, Cpe, and another one that was modified with Zn Al layered double hydroxides (Cpe/Zn Al-LDH). The electro-oxidation was effected at ph values ranging from 3 up to 11. It was found through cyclic voltammetry that this process was irreversible, namely, there were no reduction peaks, and that depending on the nature of the electrode, the anodic current was limited either by adsorption (Cpe) or diffusion (Cpe/Zn Al-LDH). The energy required and the oxidation reaction rate depended on the ph and on the nature of the electrode, such that the greater rates were obtained when the Cpe/Zn Al-LDH electrode and acid ph were used. The Zn Al-LDH was characterized by means of X-ray diffraction. (Author)

  16. ELECTROCHEMICAL DETERMINATION OF ETHANOL, 2- PROPANOL AND 1-BUTANOL ON GLASSY CARBON ELECTRODE MODIFIED WITH NICKEL OXIDE FILM

    Directory of Open Access Journals (Sweden)

    A. Benchettara

    2014-12-01

    Full Text Available In this work, we present the modification of a glassy carbon electrode with nickel oxide film which is performed in two successive steps. In the first one, the electrochemical deposition of metallic nickel on the glassy carbon electrode (GCE is achieved in 0.1M boric acid; in the second step, the metallic deposit is anodically oxidized in 0.1M NaOH. These two operations were carried out in a three electrode cell with a filiform platinum auxiliary electrode, a SCE as potential reference and a working microelectrode of modified glassy carbon with nickel oxides. This electrode is characterized by several electrochemical techniques and is used for the catalytic determination of ethanol, 2-propanol and 1-butanol in 0.1 M NaOH. The proposed chemical mechanism shows that NiO2 acts as a mediator.

  17. Preparation, characterization and electrocatalytic behavior of zinc oxide/zinchexacyanoferrate and ruthenium oxide hexacyanoferrate hybrid film-modified electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Chu, H.-W.; Thangamuthu, R. [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, No. 1, Section 3, Chung-Hsiao East Road, Taipei 106, Taiwan (China); Chen, S.-M. [Department of Chemical Engineering and Biotechnology, National Taipei University of Technology, No. 1, Section 3, Chung-Hsiao East Road, Taipei 106, Taiwan (China)], E-mail: smchen78@ms15.hinet.net

    2008-02-15

    Polynuclear mixed-valent hybrid films of zinc oxide/zinchexacyanoferrate and ruthenium oxide hexacyanoferrate (ZnO/ZnHCF-RuOHCF) have been deposited on electrode surfaces from H{sub 2}SO{sub 4} solution containing Zn(NO{sub 3}){sub 2}, RuCl{sub 3} and K{sub 3}[Fe(CN){sub 6}] by potentiodynamic cycling method. Simultaneous cyclic voltammetry and electrochemical quartz crystal microbalance (EQCM) measurements demonstrate the steady growth of hybrid film. Surface morphology of hybrid film was investigated using scanning electron microscopy (SEM). Energy dispersive spectrometer (EDS) data confirm existence of zinc oxide and ruthenium oxide hexacyanoferrate (RuOHCF) in the hybrid film. The effect of type of monovalent cations on the redox behavior of hybrid film was investigated. In pure supporting electrolyte, electrochemical responses of Ru{sup II/III} redox transition occurring at negative potential region resemble with that of a surface immobilized redox couple. The electrocatalytic activity of ZnO/ZnHCF-RuOHCF hybrid film was investigated towards oxidation of epinephrine, dopamine and L-cysteine, and reduction of S{sub 2}O{sub 8}{sup 2-} and SO{sub 5}{sup 2-} as well as IO{sub 3}{sup -} using cyclic voltammetry and rotating ring disc electrode (RRDE) techniques.

  18. Plasma clearance and biodistribution of oxidatively modified 99mTc-ß-VLDL in rabbits

    Directory of Open Access Journals (Sweden)

    Silva E.L.

    1997-01-01

    Full Text Available The biodistribution and removal from plasma (measured as fractional clearance rate, FCR, per hour of native and oxidatively modified 99mtechnetium-labeled ß-very low density lipoprotein (99mTc-ß-VLDL were investigated in hypercholesterolemic (HC and control (C three-month old New Zealand rabbits. The intracellular accumulation of ß-VLDL labeled with 99mTc was studied in vitro in THP-1 cells and monocyte-derived macrophages isolated from rabbits. After intravenous injection into C rabbits, copper-oxidized ß-VLDL (99mTc-ox-ß-VLDL was cleared from the circulation faster (0.362 ± 0.070/h than native ß-VLDL (99mTc-nat-ß-VLDL, 0.241 ± 0.070/h. In contrast, the FCR of 99mTc-ox-ß-VLDL in HC rabbits was lower (0.100 ± 0.048/h than that of 99mTc-nat-ß-VLDL (0.163 ± 0.043/h. The hepatic uptake of radiolabeled lipoproteins was lower in HC rabbits (0.114 ± 0.071% injected dose/g tissue for 99mTc-nat-ß-VLDL and 0.116 ± 0.057% injected dose/g tissue for 99mTc-ox-ß-VLDL than in C rabbits (0.301 ± 0.113% injected dose/g tissue for 99mTc-nat-ß-VLDL and 0.305 ± 0.149% injected dose/g tissue for 99mTc-ox-ß-VLDL. The uptake of 99mTc-nat-ß-VLDL and 99mTc-ox-ß-VLDL by atherosclerotic aorta lesions isolated from HC rabbits (99mTc-nat-ß-VLDL: 0.033 ± 0.012% injected dose/g tissue and 99mTc-ox-ß-VLDL: 0.039 ± 0.017% injected dose/g tissue was higher in comparison to that of non-atherosclerotic aortas from C rabbits (99mTc-nat-ß-VLDL: 0.023 ± 0.010% injected dose/g tissue and 99mTc-ox-ß-VLDL: 0.019 ± 0.010% injected dose/g tissue. However, 99mTc-nat-ß-VLDL and 99mTc-ox-ß-VLDL were taken up by atherosclerotic lesions at similar rates. In vitro studies showed that both monocyte-derived macrophages isolated from rabbits and THP-1 macrophages significantly internalized more 99mTc-ox-ß-VLDL than 99mTc-nat-ß-VLDL. These results indicate that in cholesterol-fed rabbits 99mTc-ox-ß-VLDL is slowly cleared from plasma and accumulates in

  19. Does methyl jasmonate modify the oxidative stress response in Phaseolus coccineus treated with Cu?

    Science.gov (United States)

    Hanaka, Agnieszka; Wójcik, Małgorzata; Dresler, Sławomir; Mroczek-Zdyrska, Magdalena; Maksymiec, Waldemar

    2016-02-01

    The contribution of methyl jasmonate (MJ) as a signal molecule able to take part in the defense mechanism against copper (Cu)-imposed oxidative stress was studied in the leaves and roots of runner bean (Phaseolus coccineus) plants. Roots of plants cultivated hydroponically were preincubated in MJ (10µM) for 1h or 24h and subsequently exposed to Cu (50µM) for 5h (short-term experiment) or 5 days (long-term experiment). Enzymatic (activity of superoxide dismutase, SOD; catalase, CAT; ascorbate peroxidase, APX; guaiacol peroxidase, POX) and non-enzymatic (accumulation of malondialdehyde, MDA; homoglutathione, hGSH; proline; anthocyanins; low molecular weight organic acids, LMWOAs) responses were determined in the leaves and roots. The antioxidative defense mechanism was significantly activated after Cu supplementation. In most cases, activities of ROS (reactive oxygen species) scavenging enzymes like SOD, CAT, APX, POX, as well as MDA, hGSH and proline concentrations increased following Cu exposure. MJ showed a time-dependent effect on antioxidative enzymes activity. In the short-term experiment, MJ elevated CAT, APX and POX activities in the roots, and POX activity in the leaves of non-Cu-treated plants. In the long-term experiment, MJ not only decreased POX and partially CAT activity in the roots, but also increased the MDA level and partially CAT activity in the leaves of the control plants. In Cu-treated plants, MJ reduced APX, but elevated POX activity in the leaves after 5-h exposure. After 5-day-Cu treatment, MJ inhibited POX activity in the leaves and mainly reduced SOD and CAT activities in the roots. Moreover, in the long-term experiment, MJ reduced tartrate and pyruvate in the leaves of Cu-stressed plants, but mostly elevated tartrate and malate in the roots comparing with Cu alone treatment. MJ alone and under Cu excess did not alter accumulation of MDA, hGSH and proline comparing with Cu alone, but partially elevated anthocyanin concentration. The

  20. Zeolites Modified Metal Cations as Catalysts in Hydrocarbon Oxidation and the Alkyl Alcohol

    Directory of Open Access Journals (Sweden)

    Agadadsh Makhmud Aliyev

    2014-09-01

    Full Text Available The results of studies on the creation of highly metalltceolitnyh systems and the study of their catalytic activities in the oxidation of lower olefin hydrocarbons (ethylene to acetaldehyde, acetone, propylene, butylene methyl ethyl ketone; aliphatic C1-C5 alcohols to their corresponding aldehydes, ketones, carboxylic acids and carboxylic acid esters; oxidative dehydrogenation of naphthenes in the alicyclic diene hydrocarbons and the oxidative dimerization of methane to acetylene. It has been established that the selectivity of these catalysts determined optimal combination of metal components with the acidity and the structure of the zeolite. Selected highly effective catalysts for the reactions studied. Based on the results of experimental studies of the kinetics of the reactions of oxidation of lower olefin hydrocarbons and aliphatic alcohols, the oxidative dehydrogenation of naphthenes and oxidative coupling of methane on the synthesized catalysts are represented by their probable stepwise mechanism and kinetic models developed reactions.

  1. Redox and electrochemical water splitting catalytic properties of hydrated metal oxide modified electrodes.

    Science.gov (United States)

    Doyle, Richard L; Godwin, Ian J; Brandon, Michael P; Lyons, Michael E G

    2013-09-07

    This paper presents a review of the redox and electrocatalytic properties of transition metal oxide electrodes, paying particular attention to the oxygen evolution reaction. Metal oxide materials may be prepared using a variety of methods, resulting in a diverse range of redox and electrocatalytic properties. Here we describe the most common synthetic routes and the important factors relevant to their preparation. The redox and electrocatalytic properties of the resulting oxide layers are ascribed to the presence of extended networks of hydrated surface bound oxymetal complexes termed surfaquo groups. This interpretation presents a possible unifying concept in water oxidation catalysis - bridging the fields of heterogeneous electrocatalysis and homogeneous molecular catalysis.

  2. Effect of Grinding at Modified Atmosphere or Vacuum on Browning, Antioxidant Capacities, and Oxidative Enzyme Activities of Apple.

    Science.gov (United States)

    Kim, Ah-Na; Lee, Kyo-Yeon; Kim, Hyun-Jin; Chun, Jiyeon; Kerr, William L; Choi, Sung-Gil

    2018-01-01

    This study evaluated the effects of grinding at atmospheric pressure (control), under vacuum (∼2.67 kPa), or with modified atmosphere (N 2 and CO 2 ) on the browning, antioxidant activity, phenolics, and oxidative enzyme activity of apples as a function of time. The control group was affected most, showing distinct browning and losing most of the antioxidant activity and concentrations of the main phenolic compounds. The modified atmosphere groups retained color, antioxidant activity, and phenolic compounds better than the control group. Least changes were obtained with vacuum grinding, particularly in terms of preventing enzymatic browning and oxidation of antioxidants apples. At 12 h after grinding, vacuum-ground apples retained total phenolic contents 5.32, 1.54, and 1.49 times higher than control, nitrogen gas, and carbon dioxide gas-ground samples, respectively. The oxidative enzyme activity, including that of polyphenol oxidase and peroxidase, decreased in the control and modified atmosphere group, but they were maintained in the samples ground under the vacuum. In this study, we found that grinding with modified atmosphere or vacuum conditions could effectively prevent browning as well as loss of phenolic compounds and antioxidant activity of ground apples. These results can help scientists and engineers build better grinding systems for retaining nutrient and quality factors of ground apples. In addition, these results may be useful to other fruit and vegetable industries that wish to retain fresh-like quality and nutritional value during grinding and storage. © 2017 Institute of Food Technologists®.

  3. Fabrication of electrochemical theophylline sensor based on manganese oxide nanoparticles/ionic liquid/chitosan nanocomposite modified glassy carbon electrode

    International Nuclear Information System (INIS)

    MansouriMajd, Samira; Teymourian, Hazhir; Salimi, Abdollah; Hallaj, Rahman

    2013-01-01

    In this study, the preparation of a glassy carbon (GC) electrode modified with chitosan/NH 2 -ionic liquid/manganese oxide nanoparticles (Chit/NH 2 -IL/MnO x ) was described for electrocatalytic detection of theophylline (TP). First, chitosan hydrogel (Chit) was electrodeposited on the GC electrode surface at a constant potential (−1.5 V) in acidic solution. Then, the previously synthesized amine-terminated 1-(3-Aminopropyl)-3-methylimidazolium bromide ionic liquid (NH 2 -IL) was covalently attached to the modified electrode via glutaraldehyde (GA) as linking agent. Finally, manganese oxide (MnO x ) nanoparticles were electrodeposited onto the Chit/NH 2 -IL film by potential cycling between −1.0 and 1.7 V in Mn(CH 3 COO) 2 ·4H 2 O neutral aqueous solution. Electrochemical behavior of the modified electrode was evaluated by cyclic voltammetry (CV) technique. The charge transfer coefficient (α) and electron transfer rate constant (k s ) for MnOOH/MnO 2 redox couple were calculated to be 0.35 and 1.62 s −1 , respectively. The resulting system brings new capabilities for electrochemical sensing through combining the advantages of IL and MnO x nanoparticles. The differential pulse voltammetric (DPV) results indicated the high ability of GC/Chit/NH 2 -IL/MnO x modified electrode to catalyze the oxidation of TP. DPV determination of TP in acetate buffer solution (pH 5) gave linear responses over the concentration range up to 120 μM with the detection limit of 50 nM and sensitivity of 804 nA μM −1 . Furthermore, the applicability of the sensor for TP analysis in pharmaceutical samples has been successfully demonstrated

  4. Phosphate Remediation and Recovery from Lake Water using Modified Iron Oxide-based Adsorbents

    Science.gov (United States)

    Adsorption behavior of Bayoxide ® E33 (E33) and three E33-modified sorbents for the removal of phosphate from lake water was investigated in this study. E33-modified sorbents were synthesized by coating with manganese and nanoparticles. Characterization was done by X-ray diffract...

  5. Directed synthesis of bio-inorganic vanadium oxide composites using genetically modified filamentous phage

    International Nuclear Information System (INIS)

    Mueller, Michael; Baik, Seungyun; Jeon, Hojeong; Kim, Yuchan; Kim, Jungtae; Kim, Young Jun

    2015-01-01

    Highlights: • Phage is an excellent seeding for bio-templates for environmentally benign vanadium oxide nanocomposite synthesis. • The synthesized bio-inorganic vanadium oxide showed photodegradation activities. • The fabricated wt phage/vanadium oxide composite exhibited bundle-like structure. • The fabricated RSTB-phage/vanadium oxide composite exhibited a ball with a fiber-like nanostructure. • The virus/vanadium oxide composite could be applied in photocatalysts, sensors and nanoelectronic applications. - Abstract: The growth of crystalline vanadium oxide using a filamentous bacteriophage template was investigated using sequential incubation in a V 2 O 5 precursor. Using the genetic modification of the bacteriophage, we displayed two cysteines that constrained the RSTB-1 peptide on the major coat protein P8, resulting in vanadium oxide crystallization. The phage-driven vanadium oxide crystals with different topologies, microstructures, photodegradation and vanadium oxide composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), quartz microbalance and dissipation (QCM-D) and X-ray photoelectron spectroscopy (XPS). Non-specific electrostatic attraction between a wild-type phage (wt-phage) and vanadium cations in the V 2 O 5 precursor caused phage agglomeration and fiber formation along the length of the viral scaffold. As a result, the addition of recombinant phage (re-phage) in V 2 O 5 precursors formed heterogeneous structures, which led to efficient condensation of vanadium oxide crystal formation in lines, shown by QCM-D analysis. Furthermore, re-phage/V x O x composites showed significantly enhanced photodegradation activities compared with the synthesized wt-phage-V 2 O 5 composite under illumination. This study demonstrates that peptide-mediated vanadium oxide mineralization is governed by a complicated interplay of peptide sequence, local structure, kinetics and the presence of a mineralizing

  6. Enhanced electrocatalytic activity of pulse deposited Pt particles dispersed on PEDOT-modified Au electrode towards ethanol oxidation

    International Nuclear Information System (INIS)

    Mendoza, Maria Krisandra L.; Tongol, Bernard John V.

    2013-01-01

    Poly(3,4-ethylenedioxythiophene) (PEDOT)-modified Au electrodes were electrochemically prepared via potentiodynamic polymerization using 0.01 M EDOT and 0.10 M HClO 4 on a Au substrate at a potential range from 0.0 to 1.10 V (vs. Ag/AgCl). The PEDOT-modified AU electrode was electrochemically characterized in a monomer-free 0.10M HClO 4 electrolyte. Meanwhile, the surface morphology was probed using Scanning Electron Microscopy (SEM). Platinum particles dispersed on PEDOT-modified Au electrodes were prepared in two steps: (i) aqueous electropolymerization of EDOT and (ii) pulse deposition of platinum. Pulse deposition of Pt nanoparticles was carried out using the following optimized parameters: -30 mA/cm”2 of pulse current with 0.2 s on-time and 0.4 s off-time at 700 pulses. Electrocatalytic activity of the prepared Pt/PEDOT/Au electrode was evaluated towards ethanol oxidation using 1.0 M ethanol in 0.10 M H 2 SO 4 electrolyte solution from E = 0.0 V to E = 0.90 V (vs. Ag/AgCl) at a scan rate of 100 mV s”-“1. The CV profile of the prepared nanocomposite shows an anodic peak at E = +0.700V which is an indication of the presence of the platinum. Examination of the surface morphology of the Pt nanoparticles (Pt NPs)/PEDOT/Au-modified electrode revealed well-dispersed platinum particles on the polymer matrix with a diameter of less than 100 nm. Enhancement of the electrocatalytic activity towards ethanol oxidation was observed in pulse-deposited platinum particles compared to potentiodynamically-deposited platinum particles on PEDOT-modified Au electrode. (author)

  7. Ethanol Total Oxidation Over Calcined Layered Double Hydroxides Modified with Organic Components

    Czech Academy of Sciences Publication Activity Database

    Ludvíková, Jana; Jirátová, Květa; Klempa, Jan; Raabová, H.; Zapivovarski Votipka, Z.; Kovanda, F.

    2013-01-01

    Roč. 62, 5-6 (2013), s. 137-146 ISSN 0022-9830 R&D Projects: GA ČR GAP106/10/1762 Institutional support: RVO:67985858 Keywords : mixed oxides * Pluronic 123 * VOC oxidation Subject RIV: CI - Industrial Chemistry, Chemical Engineering

  8. Oxidation behavior of Hf-modified platinum aluminide coatings during thermal cycling

    Directory of Open Access Journals (Sweden)

    Liya Ye

    2018-02-01

    Full Text Available Platinum aluminide coatings with different Hf contents were fabricated by using HfCl4. The oxidation kinetics and the rumpling behavior of oxide scale were investigated. After thermal cycling, the coating with 0.46 wt% Hf showed least weight gain. With the increase of Hf content, rumpling extent of the scale decreased. Meanwhile, HfO2 preferentially formed in the scale resulting in the increase of scale thickness. The oxidation of excessive Hf even caused the spallation of the scale. The results in the present study indicate that although Hf plays an important role in decreasing rumpling extent of TGO, the oxidation of Hf decreases the adhesion of the scale. Keywords: Pt-Al coating, Hf, Oxidation, Rumpling

  9. Enhanced photoluminescence in transparent thin films of polyaniline–zinc oxide nanocomposite prepared from oleic acid modified zinc oxide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sajimol Augustine, M., E-mail: sajimollazar@gmail.com [Department of Physics, St. Teresa' s College, Kochi-11, Kerala (India); Jeeju, P.P.; Varma, S.J.; Francis Xavier, P.A. [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Kochi-22, Kerala (India); Jayalekshmi, S., E-mail: lakshminathcusat@gmail.com [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Kochi-22, Kerala (India)

    2014-07-01

    Oleic acid capped zinc oxide (ZnO) nanoparticles have been synthesized by a wet chemical route. The chemical oxidative method is employed to synthesize polyaniline (PANI) and PANI/ZnO nanocomposites doped with four different dopants such as orthophosphoric acid (H{sub 3}PO{sub 4}), hydrochloric acid (HCl), naphthalene-2-sulphonic acid and camphor sulphonic acid (CSA). The samples have been structurally characterized by X-ray diffraction (XRD), field emission scanning electron microscopy and Fourier transform infrared (FT-IR) spectroscopic techniques. A comparison of the photoluminescence (PL) emission intensity of PANI and PANI/ZnO nanocomposites is attempted. The enhanced PL intensity in PANI/ZnO nanocomposites is caused by the presence of nanostructured and highly fluorescent ZnO in the composites. It has been observed that, among the composites, the H{sub 3}PO{sub 4} doped PANI/ZnO nanocomposite is found to exhibit the highest PL intensity because of the higher extent of (pi) conjugation and the more orderly arrangement of the benzenoid and quinonoid units. In the present work, transparent thin films of PANI and PANI/ZnO nanocomposite for which PL intensity is found to be maximum, have been prepared after re-doping with CSA by the spin-coating technique. The XRD pattern of the PANI/ZnO film shows exceptionally good crystallanity compared to that of pure PANI, which suggests that the addition of ZnO nanocrystals helps in enhancing the crystallanity of the PANI/ZnO nanocomposite. There is a significant increase in the PL emission intensity of the PANI/ZnO nanocomposite film making it suitable for the fabrication of optoelectronic devices. - Highlights: • Oleic acid capped zinc oxide nanoparticles are synthesized by wet chemical method. • Polyaniline/zinc oxide nanocomposites are prepared by in-situ polymerization. • Polyaniline and polyaniline/zinc oxide thin films are deposited using spin-coating. • Enhanced photoluminescence is observed in polyaniline

  10. Electrocatalytic oxidation behavior of NADH at Pt/Fe{sub 3}O{sub 4}/reduced-graphene oxide nanohybrids modified glassy carbon electrode and its determination

    Energy Technology Data Exchange (ETDEWEB)

    Roushani, Mahmoud, E-mail: mahmoudroushani@yahoo.com [Department of Chemistry, Faculty of Sciences, Ilam University, Ilam, 69315516 (Iran, Islamic Republic of); Hoseini, S. Jafar [Department of Chemistry, Faculty of Sciences, Yasouj University, Yasouj, 7591874831 (Iran, Islamic Republic of); Azadpour, Mitra [Department of Chemistry, Faculty of Sciences, Ilam University, Ilam, 69315516 (Iran, Islamic Republic of); Heidari, Vahid; Bahrami, Mehrangiz; Maddahfar, Mahnaz [Department of Chemistry, Faculty of Sciences, Yasouj University, Yasouj, 7591874831 (Iran, Islamic Republic of)

    2016-10-01

    We have developed Pt/Fe{sub 3}O{sub 4}/reduced-graphene oxide nanohybrids modified glassy carbon (Pt/Fe{sub 3}O{sub 4}/RGO/GC) electrode as a novel system for the preparation of electrochemical sensing platform. Characterization of as-made composite was determined using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM) and energy-dispersive analysis of X-ray (EDAX) where the Pt, Fe, Si, O and C elements were observed. The Pt/Fe{sub 3}O{sub 4}/RGO/GC electrode was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Due to the synergistic effect between Pt, Fe{sub 3}O{sub 4} and RGO, the nanohybrid exhibited excellent performance toward dihydronicotinamide adenine dinucleotide (NADH) oxidation in 0.1 M phosphate buffer solution, pH 7.0, with a low detection limit of 5 nM. - Highlights: • Preparation of a novel electrochemical sensing platform system • Excellent performance of Pt/Fe{sub 3}O{sub 4}/reduced-graphene oxide nanohybrids • Dihydronicotinamide adenine dinucleotide oxidation with a low detection limit of 5 nM.

  11. Directed synthesis of bio-inorganic vanadium oxide composites using genetically modified filamentous phage

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, Michael; Baik, Seungyun [Environmental Safety Group, Korea Institute of Science and Technology Europe (KIST-Europe) Forschungsgesellschaft mbH, Campus E 7 1, Saarbruecken (Germany); Jeon, Hojeong; Kim, Yuchan [Center for Biomaterials, Biomedical Research Institute Korea Institute of Science and Technology (KIST), Hwarangno 14-gil 5, Seongbuk-gu, Seoul 136-791 (Korea, Republic of); Kim, Jungtae [Environmental Safety Group, Korea Institute of Science and Technology Europe (KIST-Europe) Forschungsgesellschaft mbH, Campus E 7 1, Saarbruecken (Germany); Kim, Young Jun, E-mail: youngjunkim@kist-europe.de [Environmental Safety Group, Korea Institute of Science and Technology Europe (KIST-Europe) Forschungsgesellschaft mbH, Campus E 7 1, Saarbruecken (Germany)

    2015-05-15

    Highlights: • Phage is an excellent seeding for bio-templates for environmentally benign vanadium oxide nanocomposite synthesis. • The synthesized bio-inorganic vanadium oxide showed photodegradation activities. • The fabricated wt phage/vanadium oxide composite exhibited bundle-like structure. • The fabricated RSTB-phage/vanadium oxide composite exhibited a ball with a fiber-like nanostructure. • The virus/vanadium oxide composite could be applied in photocatalysts, sensors and nanoelectronic applications. - Abstract: The growth of crystalline vanadium oxide using a filamentous bacteriophage template was investigated using sequential incubation in a V{sub 2}O{sub 5} precursor. Using the genetic modification of the bacteriophage, we displayed two cysteines that constrained the RSTB-1 peptide on the major coat protein P8, resulting in vanadium oxide crystallization. The phage-driven vanadium oxide crystals with different topologies, microstructures, photodegradation and vanadium oxide composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), quartz microbalance and dissipation (QCM-D) and X-ray photoelectron spectroscopy (XPS). Non-specific electrostatic attraction between a wild-type phage (wt-phage) and vanadium cations in the V{sub 2}O{sub 5} precursor caused phage agglomeration and fiber formation along the length of the viral scaffold. As a result, the addition of recombinant phage (re-phage) in V{sub 2}O{sub 5} precursors formed heterogeneous structures, which led to efficient condensation of vanadium oxide crystal formation in lines, shown by QCM-D analysis. Furthermore, re-phage/V{sub x}O{sub x} composites showed significantly enhanced photodegradation activities compared with the synthesized wt-phage-V{sub 2}O{sub 5} composite under illumination. This study demonstrates that peptide-mediated vanadium oxide mineralization is governed by a complicated interplay of peptide sequence, local structure

  12. Electrocatalytic oxidation of dihydronicotineamide adenine dinucleotide on gold electrode modified with catechol-terminated alkanethiol self-assembly

    International Nuclear Information System (INIS)

    Nakano, Koji; Ohkubo, Kimihiko; Taira, Hiroaki; Takagi, Makoto; Imato, Toshihiko

    2008-01-01

    Synthesis of a mercaptoundecaneamide derivative having a terminus of catechol is described. FT-IR spectroscopic characterization showed that the new molecular entry simply undergoes molecular self-assembly on Au substrate surfaces promoting intra- and intermolecular hydrogen bonds to form well-packed monolayers. Cyclic voltammetric (CV) measurements on the monolayer-modified Au electrode revealed that the surface adlayer possesses specific electrochemical activity due to the reversible catechol/o-quinone redox reaction having characteristics of a surface process and also pH-dependence in its formal potential (59 mV per pH). Detailed analysis of CVs gave fundamental electrochemical parameters including the electroactive surface coverage (0.20-0.24 nmol cm -2 ), the transfer coefficients (0.24 in oxidation and 0.81 in reduction), and also the electron transfer rate constant (1.10-2.76 s -1 ). These data were almost consistent to those seen in literature. We have also found that the catechol monolayer modified electrode exhibits an electrocatalytic function in NADH oxidation. That is, the faradaic current appeared reinforcingly at around the same potential where catechol function is oxidized in the monolayer and increased with an increase in the NADH concentration from 1 to 5 mM, and then reached to a plateau indicating a catalyzed reaction pathway. Detailed analyses revealed that the present system could be characterized by its weak stability of the intermediate compound formed and prompt reaction rate compared with the previously reported chemically modified electrode (CME) systems. We think this type of achievement should be important for the basics of biosensors that rely on dehydrogenase enzymes

  13. A glassy carbon electrode modified with graphene oxide and silver nanoparticles for amperometric determination of hydrogen peroxide

    International Nuclear Information System (INIS)

    Noor, An’amt Mohamed; Shahid, Muhammad Mehmood; Rameshkumar, Perumal; Huang, Nay Ming

    2016-01-01

    The article describes a glassy carbon electrode (GCE) modified with a nanocomposite consisting of graphene oxide and silver nanoparticles, and its application to amperometric determination of hydrogen peroxide (H 2 O 2 ). Cyclic voltammetry with this modified electrode reveals efficient electrocatalytic reduction of H 2 O 2 . The response to H 2 O 2 at a working potential of −0.3 V (vs. Ag/AgCl) is linear in the 100 μM to 11 mM concentration range at pH 7.2. The limit of detection is 28.3 μM (at an S/N ratio of 3). Good selectivity is observed over physiological interferents such as dopamine, ascorbic acid, uric acid and glucose. (author)

  14. Detection of Guanine and Adenine Using an Aminated Reduced Graphene Oxide Functional Membrane-Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Di Li

    2017-07-01

    Full Text Available A new electrochemical sensor based on a Nafion, aminated reduced graphene oxide and chitosan functional membrane-modified glassy carbon electrode was proposed for the simultaneous detection of adenine and guanine. Fourier transform-infrared spectrometry (FTIR, transmission electron microscopy (TEM, and electrochemical methods were utilized for the additional characterization of the membrane materials. The prepared electrode was utilized for the detection of guanine (G and adenine (A. The anodic peak currents to G and A were linear in the concentrations ranging from 0.1 to 120 μM and 0.2 to 110 μM, respectively. The detection limits were found to be 0.1 μM and 0.2 μM, respectively. Moreover, the modified electrode could also be used to determine G and A in calf thymus DNA.

  15. Improved Electrochemical Detection of Zinc Ions Using Electrode Modified with Electrochemically Reduced Graphene Oxide

    Czech Academy of Sciences Publication Activity Database

    Kudr, J.; Richtera, L.; Nejdl, L.; Xhaxhiu, K.; Vítek, Petr; Rutkay-Nedecky, B.; Hynek, D.; Kopel, P.; Adam, V.; Kižek, R.

    2016-01-01

    Roč. 9, č. 1 (2016), UNSP 31 ISSN 1996-1944 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : carbon * cyclic voltammetry * electrochemical impedance spectroscopy * electrochemistry * graphene oxide * heavy metal detection * reduced graphene oxide Subject RIV: CG - Electrochemistry OBOR OECD: Electrochemistry (dry cells, batteries, fuel cells, corrosion metals, electrolysis) Impact factor: 2.654, year: 2016

  16. Emergent macrophytes modify the abundance and community composition of ammonia oxidizers in their rhizosphere sediments.

    Science.gov (United States)

    Zhao, Dayong; He, Xiaowei; Huang, Rui; Yan, Wenming; Yu, Zhongbo

    2017-07-01

    Ammonia oxidation is a crucial process in global nitrogen cycling, which is catalyzed by the ammonia oxidizers. Emergent plants play important roles in the freshwater ecosystem. Therefore, it is meaningful to investigate the effects of emergent macrophytes on the abundance and community composition of ammonia oxidizers. In the present study, two commonly found emergent macrophytes (Zizania caduciflora and Phragmitas communis) were obtained from freshwater lakes and the abundance and community composition of the ammonia-oxidizing prokaryotes in the rhizosphere sediments of these emergent macrophytes were investigated. The abundance of the bacterial amoA gene was higher in the rhizosphere sediments of the emergent macrophytes than those of bulk sediments. Significant positive correlation was found between the potential nitrification rates (PNRs) and the abundance of bacterial amoA gene, suggesting that ammonia-oxidizing bacteria (AOB) might play an important role in the nitrification process of the rhizosphere sediments of emergent macrophytes. The Nitrosotalea cluster is the dominant ammonia-oxidizing archaea (AOA) group in all the sediment samples. Analysis of AOB group showed that the N. europaeal cluster dominated the rhizosphere sediments of Z. caduciflora and the bulk sediments, whereas the Nitrosospira cluster was the dominant AOB group in the rhizosphere sediments of P. communis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Directed synthesis of bio-inorganic vanadium oxide composites using genetically modified filamentous phage

    Science.gov (United States)

    Mueller, Michael; Baik, Seungyun; Jeon, Hojeong; Kim, Yuchan; Kim, Jungtae; Kim, Young Jun

    2015-05-01

    The growth of crystalline vanadium oxide using a filamentous bacteriophage template was investigated using sequential incubation in a V2O5 precursor. Using the genetic modification of the bacteriophage, we displayed two cysteines that constrained the RSTB-1 peptide on the major coat protein P8, resulting in vanadium oxide crystallization. The phage-driven vanadium oxide crystals with different topologies, microstructures, photodegradation and vanadium oxide composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), quartz microbalance and dissipation (QCM-D) and X-ray photoelectron spectroscopy (XPS). Non-specific electrostatic attraction between a wild-type phage (wt-phage) and vanadium cations in the V2O5 precursor caused phage agglomeration and fiber formation along the length of the viral scaffold. As a result, the addition of recombinant phage (re-phage) in V2O5 precursors formed heterogeneous structures, which led to efficient condensation of vanadium oxide crystal formation in lines, shown by QCM-D analysis. Furthermore, re-phage/VxOx composites showed significantly enhanced photodegradation activities compared with the synthesized wt-phage-V2O5 composite under illumination. This study demonstrates that peptide-mediated vanadium oxide mineralization is governed by a complicated interplay of peptide sequence, local structure, kinetics and the presence of a mineralizing aid, such as the two cysteine-constrained peptides on the phage surface, and has potential for use in nanotechnology applications.

  18. Microstructural Study on Oxidation Resistance of Nonmodified and Platinum Modified Aluminide Coating

    Science.gov (United States)

    Zagula-Yavorska, Maryana; Sieniawski, Jan

    2014-03-01

    Platinum electroplating layers (3 and 7 μm thick) were deposited on the surface of the Inconel 713 LC, CMSX 4, and Inconel 625 Ni-base superalloys. Diffusion treatment at 1050°C for 2 h under argon atmosphere was performed after electroplating. Diffusion treated samples were aluminized according to the low activity CVD process at 1050°C for 8 h. The nonmodified aluminide coatings consist of NiAl phase. Platinum modification let to obtain the (Ni,Pt)Al phase in coatings. The coated samples were subjected to cyclic oxidation testing at 1100°C. It was discovered that increase of the platinum electroplating thickness from 3 to 7 μm provides the improvement of oxidation resistance of aluminide coatings. Increase of the platinum thickness causes decreases in weight change and decreases in parabolic constant during oxidation. The platinum provides the pure Al2O3 oxide formation, slow growth oxide layer, and delay the oxide spalling during heating-cooling thermal cycles.

  19. Kinetics of the oxidative hydroxylation of tetraphosphorus in the presence of copper(II chloride modified by humic (fulvo- acid

    Directory of Open Access Journals (Sweden)

    Zhaksyntay Kairbekov

    2012-12-01

    Full Text Available It was established that in mild conditions (50-70 oC, РО2= 1 atm white phosphorus effectively is oxidized by oxygen in water-toluene solutions of copper(II chloride modified by humic (fulvo- acid to give mainly phosphoric acid. Humic (fulvo- acid was extracted from brown coal of domestic deposit Kiyakty. For determination of optimum parameters of fulvo-acid extraction the laboratory experiments were carried out using the method of experiment planning. The kinetics, intermediate and final products, optimum conditions of new catalytic reaction of P4 oxidation by oxygen in water medium were defined by kinetics, volumometry, redox-potentiometry, 31Р{1Н} NMR spectroscopy and  titration. 

  20. Label-free, electrochemical detection of methicillin-resistant staphylococcus aureus DNA with reduced graphene oxide-modified electrodes

    KAUST Repository

    Wang, Zhijuan

    2011-05-01

    Reduced graphene oxide (rGO)-modified glassy carbon electrode is used to detect the methicillin-resistant Staphylococcus aureus (MRSA) DNA by using electrochemical impedance spectroscopy. Our experiments confirm that ssDNA, before and after hybridization with target DNA, are successfully anchored on the rGO surface. After the probe DNA, pre-adsorbed on rGO electrode, hybridizes with target DNA, the measured impedance increases dramatically. It provides a new method to detect DNA with high sensitivity (10-13M, i.e., 100 fM) and selectivity. © 2011 Elsevier B.V.

  1. Preparation of alanine and tyrosine functionalized graphene oxide nanoflakes and their modified carbon paste electrodes for the determination of dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Mohan [Department of P.G. Studies and Research in Industrial Chemistry, Kuvempu University, Shankaraghatta, 577 451, Shimoga, Karnataka (India); Swamy, B.E. Kumara, E-mail: kumaraswamy21@yahoo.com [Department of P.G. Studies and Research in Industrial Chemistry, Kuvempu University, Shankaraghatta, 577 451, Shimoga, Karnataka (India); Asif, M.H. Mohammed [Nanoscience and Technology, Kuvempu University, Shankaraghatta, 577451, Shimoga, Karnataka (India); Viswanath, C.C. [Department of P.G. Studies and Research in Industrial Chemistry, Kuvempu University, Shankaraghatta, 577 451, Shimoga, Karnataka (India)

    2017-03-31

    Highlights: • The prepared graphene oxide was functionalized by alanine and tyrosine. • The prepared materials were used for sensor for dopamine. • The functionalized graphene oxide modified carbon paste electrodes shows good sensitivity, stability and repeatability. - Abstract: Herein, established the synthesis of graphene oxide (GO) by Hummers Method with addition of KMnO{sub 4} followed by thermal heating at 80 °C. The obtained GO was further functionalized by alanine and tyrosine. The prepared GO, alanine functionalized GO nanoflakes (AGONF) and tyrosine functionalized GO nanoflakes (TGONF) were characterized by spectroscopic technique using energy-dispersive spectroscopy (EDS), quantitatively by scanning electron microscopy (SEM) and structural studies along with interlayer distance verified through X-ray diffraction technique. Afterwards, the prepared AGONF and TGONF were used as the modifier for the carbon paste electrode (CPE). The electrochemical behavior of the AGONF and TGONF modified carbon paste electrodes (MCPEs) towards dopamine (DA) in phosphate buffer solution (PBS) were examined by cyclic voltammetric (CV) technique and the obtained consequences showed good electrocatalytic activity of MCPEs by increasing the redox peak current with a lower potential difference compared to the bare CPE (BCPE). The AGONF and TGONF MCPEs were further used for the optimization studies. From the pH studies, it was found that the equal number of proton and electron transfer reaction involved in both the modified electrodes. The scan rate studies demonstrate the adsorption controlled electrode process at AGONF MCPE and diffusion controlled at TGONF MCPE. The oxidation peak current increased linearly with two concentration interval of DA at a range of 2–7 μM and 10–30 μM in presence of PBS (pH 7.4) at MCPEs and the limit of detection (LOD) were found to be 0.84 μM and 0.96 μM for first interval DA concentration range (2–7 μM) at AGONF and TGONF MCPE

  2. Kinetics of the oxidative hydroxylation of tetraphosphorus in the presence of copper(II) chloride modified by humic (fulvo-) acid

    OpenAIRE

    Zhaksyntay Kairbekov; Dina Akbayeva; Zh. Eshova

    2012-01-01

    It was established that in mild conditions (50-70 oC, РО2= 1 atm) white phosphorus effectively is oxidized by oxygen in water-toluene solutions of copper(II) chloride modified by humic (fulvo-) acid to give mainly phosphoric acid. Humic (fulvo-) acid was extracted from brown coal of domestic deposit Kiyakty. For determination of optimum parameters of fulvo-acid extraction the laboratory experiments were carried out using the method of experiment planning. The kinetics, intermediate and final ...

  3. Application of vanadium incorporated phosphomolybdate supported on the modified kaolinin synthesis of diphenyl carbonate by oxidative carbonylation with phenol

    Directory of Open Access Journals (Sweden)

    Peng Meng

    2017-01-01

    Full Text Available Keggin-type molybdophosphoric acid, molybdophosphoric salt and vanadium incorporated molybdophosphoric salt supported on the modified kaolin (MK were investigated as redox co-catalysts for the oxidative carbonylation of phenol to diphenyl carbonate (DPC in the absence of solvent. The 20 wt.% of MnAMPV5 (one kind of vanadium incorporated molybdophosphoric salt loaded on MK showed the highest catalytic activity with the yield of 24.68% and a TON of 306, while the selectivity amounts to nearly 100% in all the carbonylation reactions. The catalysts were characterized by XRD, BET, XPS and H2-TPR. The reusability study showed that the catalysts were stable and active.

  4. Electrochemical label-free and sensitive nanobiosensing of DNA hybridization by graphene oxide modified pencil graphite electrode.

    Science.gov (United States)

    Ahour, F; Shamsi, A

    2017-09-01

    Based on the strong interaction between single-stranded DNA (ss-DNA) and graphene material, we have constructed a novel label-free electrochemical biosensor for rapid and facile detection of short sequences ss-DNA molecules related to hepatitis C virus 1a using graphene oxide modified pencil graphite electrode. The sensing mechanism is based on the superior adsorption of single-stranded DNA to GO over double stranded DNA (ds-DNA). The intrinsic guanine oxidation signal measured by differential pulse voltammetry (DPV) has been used for duplex DNA formation detection. The probe ss-DNA adsorbs onto the surface of GO via the π- π* stacking interactions leading to a strong background guanine oxidation signal. In the presence of complementary target, formation of helix which has weak binding ability to GO induced ds-DNA to release from the electrode surface and significant variation in differential pulse voltammetric response of guanine bases. The results indicated that the oxidation peak current was proportional to the concentration of complementary strand in the range of 0.1 nM-0.5 μM with a detection limit of 4.3 × 10 -11  M. The simple fabricated electrochemical biosensor has high sensitivity, good selectivity, and could be applied as a new platform for a range of target molecules in future. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Homogeneous photochemical water oxidation by biuret-modified Fe-TAML: evidence of Fe(V)(O) intermediate.

    Science.gov (United States)

    Panda, Chakadola; Debgupta, Joyashish; Díaz Díaz, David; Singh, Kundan K; Sen Gupta, Sayam; Dhar, Basab B

    2014-09-03

    Water splitting, leading to hydrogen and oxygen in a process that mimics natural photosynthesis, is extremely important for devising a sustainable solar energy conversion system. Development of earth-abundant, transition metal-based catalysts that mimic the oxygen-evolving complex of photosystem II, which is involved in oxidation of water to O2 during natural photosynthesis, represents a major challenge. Further, understanding the exact mechanism, including elucidation of the role of active metal-oxo intermediates during water oxidation (WO), is critical to the development of more efficient catalysts. Herein, we report Fe(III) complexes of biuret-modified tetra-amidomacrocyclic ligands (Fe-TAML; 1a and 1b) that catalyze fast, homogeneous, photochemical WO to give O2, with moderate efficiency (maximum TON = 220, TOF = 0.76 s(-1)). Previous studies on photochemical WO using iron complexes resulted in demetalation of the iron complexes with concomitant formation of iron oxide nanoparticles (NPs) that were responsible for WO. Herein, we show for the first time that a high valent Fe(V)(O) intermediate species is photochemically generated as the active intermediate for the oxidation of water to O2. To the best of our knowledge, this represents the first example of a molecular iron complex catalyzing photochemical WO through a Fe(V)(O) intermediate.

  6. Catalytic oxidation of dibromomethane over Ti-modified Co3O4 catalysts: Structure, activity and mechanism.

    Science.gov (United States)

    Mei, Jian; Huang, Wenjun; Qu, Zan; Hu, Xiaofang; Yan, Naiqiang

    2017-11-01

    Ti-modified Co 3 O 4 catalysts with various Co/Ti ratios were synthesized using the co-precipitation method and were used in catalytic oxidation of dibromomethane (CH 2 Br 2 ), which was selected as the model molecule for brominated volatile organic compounds (BVOCs). Addition of Ti distorted the crystal structure and led to the formation of a Co-O-Ti solid solution. Co 4 Ti 1 (Co/Ti molar ratio was 4) achieved higher catalytic activity with a T 90 (the temperature needed for 90% conversion) of approximately 245°C for CH 2 Br 2 oxidation and higher selectivity to CO 2 at a low temperature than the other investigated catalysts. In addition, Co 4 Ti 1 was stable for at least 30h at 500ppm CH 2 Br 2 , 0 or 2vol% H 2 O, 0 or 500ppm p-xylene (PX), and 10% O 2 at a gas hourly space velocity of 60,000h -1 . The final products were CO x , Br 2 , and HBr, without the formation of other Br-containing organic byproducts. The high catalytic activity was attributed to the high Co 3+ /Co 2+ ratio and high surface acidity. Additionally, the synergistic effect of Co and Ti made it superior for CH 2 Br 2 oxidation. Furthermore, based on the analysis of products and in situ DRIFTs studies, a receivable reaction mechanism for CH 2 Br 2 oxidation over Ti-modified Co 3 O 4 catalysts was proposed. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Physicochemical and mechanical properties of zirconium oxide and niobium oxide modified Portland cement-based experimental endodontic sealers.

    Science.gov (United States)

    Viapiana, R; Flumignan, D L; Guerreiro-Tanomaru, J M; Camilleri, J; Tanomaru-Filho, M

    2014-05-01

    To evaluate the physicochemical and mechanical properties of Portland cement-based experimental sealers (ES) with different radiopacifying agents (zirconium oxide and niobium oxide micro- and nanoparticles) in comparison with the following conventional sealers: AH Plus, MTA Fillapex and Sealapex. The materials were tested for setting time, compressive strength, flow, film thickness, radiopacity, solubility, dimensional stability and formaldehyde release. Data were subjected to anova and Tukey tests (P 0.05) and lower solubility when compared with MTA Fillapex and Sealapex (P Portland cement-based experimental endodontic sealers presented physicochemical properties according to the specifications no 57 ANSI/ADA (ADA Professional Product Review, 2008) and ISO 6876 (Dentistry - Root Canal Sealing Materials, 2012, British Standards Institution, London, UK). The sealers had setting times and flow ability that was adequate for clinical use, satisfactory compressive strength and low solubility. Additional studies should be carried out with the purpose of decreasing the film thickness and to determine the ideal ratio of radiopacifying agents in Portland cement-based root canal sealers. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

  8. Facile synthesis of PtAu nanoparticles supported on polydopamine reduced and modified graphene oxide as a highly active catalyst for methanol oxidation

    International Nuclear Information System (INIS)

    Ren, Fangfang; Zhai, Chunyang; Zhu, Mingshan; Wang, Caiqin; Wang, Huiwen; Bin, Duan; Guo, Jun; Yang, Ping; Du, Yukou

    2015-01-01

    Graphical abstract: A facile and clean method for the synthesis of PtAu nanoparticles with different Pt/Au ratios supported on polydopamine reduced and modified graphene oxide (PtAu/PDA-RGO) is reported, which exhibit higher electro-catalytic performance and stability towards methanol oxidation in alkaline medium. - Highlights: • GO could be reduced and modified simultaneously by PDA without using reducing agents. • PDA plays an important role in enhancing the dispersion and stability of the catalyst. • The bimetallic PtAu/PDA-RGO catalysts exhibits higher catalytic activity than the monometallic Pt/PDA-RGO toward MOR. • The PtAu(3:1)/PDA-RGO catalyst also shows better catalytic activity for MOR than PtAu(3:1)/RGO and PtAu(3:1)/C catalysts. - Abstract: In this paper, a facile strategy for the synthesis of PtAu nanoparticles (NPs) with different Pt/Au ratios supported on polydopamine reduced and modified graphene oxide (PtAu/PDA-RGO) is reported. The as-prepared PtAu/PDA-RGO composites were extensively analyzed by transmission electron microscopy (TEM), high-resolution TEM (HRTEM), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical measurements. It is found that PDA plays an important role in enhancing the dispersion and stability of the catalyst. Moreover, the bimetallic PtAu/PDA-RGO catalysts exhibits higher catalytic activity than the monometallic Pt/PDA-RGO toward methanol oxidation reaction (MOR), with the best performance found for the Pt/Au molar ratio of 3/1. The PtAu(3:1)/PDA-RGO catalyst also shows better catalytic activity for MOR than PtAu(3:1)/RGO and PtAu(3:1)/C catalysts, suggesting that PDA-RGO can be a promising catalyst support for fuel cells. These findings also indicate that the molar ratios of Pt/Au and the catalyst support are the two critical factors to affect the overall performance of the catalyst

  9. Graphene oxide-modified ZnO particles: synthesis, characterization, and antibacterial properties

    Directory of Open Access Journals (Sweden)

    Zhong LL

    2015-08-01

    Full Text Available Linlin Zhong, Kyusik Yun Department of Bionanotechnology, Gachon University, Gyeonggi-do, Republic of Korea Abstract: Nanosized ZnO particles with diameters of 15 nm were prepared with a solution precipitation method at low cost and high yield. The synthesis of the particles was functionalized by the organic solvent dimethylformamide, and the particles were covalently bonded to the surface of graphene oxide. The morphology of the graphene oxide sheets and ZnO particles was confirmed with field emission scanning electron microscopy and biological atomic force microscopy. Fourier transform infrared spectroscopy and X-ray diffraction were used to analyze the physical and chemical properties of the ZnO/graphene oxide composites that differed from those of the individual components. Enhanced electrochemical properties were detected with cyclic voltammetry, with a redox peak of the composites at 0.025 mV. Excellent antibacterial activity of ZnO/graphene oxide composites was observed with a microdilution method in which minimum inhibitory concentrations of 6.25 µg/mL for Escherichia coli and Salmonella typhimurium, 12.5 µg/mL for Bacillus subtilis, and 25 µg/mL for Enterococcus faecalis. After further study of the antibacterial mechanism, we concluded that a vast number of reactive oxygen species formed on the surface of composites, improving antibacterial properties. Keywords: graphene oxide, ZnO, characterization, antibacterial property

  10. Oxidation of limonene using activated carbon modified in dielectric barrier discharge plasma

    Science.gov (United States)

    Glonek, Karolina; Wróblewska, Agnieszka; Makuch, Edyta; Ulejczyk, Bogdan; Krawczyk, Krzysztof; Wróbel, Rafał. J.; Koren, Zvi C.; Michalkiewicz, Beata

    2017-10-01

    The waste from industrial fruits processing is utilized for the extraction of limonene, a renewable terpene biomass compound obtained from orange peels. This was followed by limonene oxidation, which produces highly useful oxygenated derivatives (carveol, and perillyl alcohol, 1,2-epoxylimonene and its diol). New catalysts were obtained by treating relatively inexpensive commercially available EuroPh and FPV activated carbons with plasma. These catalysts were characterized by the following instrumental methods XRD, sorption of N2 and CO2, SEM, EDS, TEM, XPS, and Raman spectroscopy. The activities of the plasma-treated catalysts were measured in the oxidation of limonene by means of either hydrogen peroxide or t-butyl hydroperoxide as the oxidizing agents. During the oxidation with hydrogen peroxide the new plasma-treated catalysts were more active than their untreated counterparts. This effect was noticeable in the considerable increase in the conversion of limonene. The mechanism explaining this property is proposed, and it takes into account the role of the appropriate functional groups on the surface of the catalysts. This work has shown for the first time that the commercial EuroPh and FPV activated carbons, after having been treated by plasma, are active catalysts for the selective limonene oxidation for the production of value-added industrial products.

  11. 14C-carbaril metabolism in soils modified by organic matter oxidation and addition of glucose

    International Nuclear Information System (INIS)

    Hirata, R.; Ruegg, E.F.

    1984-01-01

    Carbaril behaviour is studied in samples of Brunizen and Dark Red Latosol soils from Parana, using radiometric techniques, with the objective of determining the role of oxidation fo its organic components, and enrichment with glucose, in the metabolism of the insecticide. Lots of autoclaved soils, oxidized and with no previous treatment, with and without glucose addition, are incubated with 14 C-carbaril and analysed during eight weeks. Its was noted that, as a result of oxidation both soils showed a marked improvement in the metabolism of the agrochemical while addition of glucose exerted litlle influence on the degrading processes. Three metabolites were detected with R sub(f) 0.23, 0.40 and 0.70. (Author) [pt

  12. Electrocatalytical oxidation and sensitive determination of acetaminophen on glassy carbon electrode modified with graphene–chitosan composite

    International Nuclear Information System (INIS)

    Zheng, Meixia; Gao, Feng; Wang, Qingxiang; Cai, Xili; Jiang, Shulian; Huang, Lizhang; Gao, Fei

    2013-01-01

    The electrochemical behaviors of acetaminophen (ACOP) on a graphene–chitosan (GR–CS) nanocomposite modified glassy carbon electrode (GCE) were investigated by cyclic voltammetry (CV), chronocoulometry (CC) and differential pulse voltammetry (DPV). Electrochemical characterization showed that the GR–CS nanocomposite had excellent electrocatalytic activity and surface area effect. As compared with bare GCE, the redox signal of ACOP on GR–CS/GCE was greatly enhanced. The values of electron transfer rate constant (k s ), diffusion coefficient (D) and the surface adsorption amount (Γ ⁎ ) of ACOP on GR–CS/GCE were determined to be 0.25 s −1 , 3.61 × 10 −5 cm 2 s −1 and 1.09 × 10 −9 mol cm −2 , respectively. Additionally, a 2e − /2H + electrochemical reaction mechanism of ACOP was deduced based on the acidity experiment. Under the optimized conditions, the ACOP could be quantified in the range from 1.0 × 10 −6 to 1.0 × 10 −4 M with a low detection limit of 3.0 × 10 −7 M based on 3S/N. The interference and recovery experiments further showed that the proposed method is acceptable for the determination of ACOP in real pharmaceutical preparations. Highlights: ► A chitosan–graphene nanocomposite modified glassy carbon electrode was prepared. ► The modified electrode was electrochemically characterized by CV and EIS. ► Electro-oxidation of acetaminophen was examined on the modified electrode. ► Sensing analysis of the modified electrode toward acetaminophen was studied

  13. Colloidally stable surface-modified iron oxide nanoparticles: preparation, characterization and anti-tumor activity

    Czech Academy of Sciences Publication Activity Database

    Macková, Hana; Horák, Daniel; Donchenko, G. V.; Andriyaka, V. I.; Palyvoda, O. M.; Chernishov, V. I.; Chekhun, V. F.; Todor, I. N.; Kuzmenko, O. I.

    2015-01-01

    Roč. 380, 15 April (2015), s. 125-131 ISSN 0304-8853. [International Conference on the Scientific and Clinical Applications of Magnetic Carriers /10./. Dresden, 10.06.2014-14.06.2014] R&D Projects: GA MŠk 7E12054; GA MŠk(CZ) LH14318; GA MŠk(CZ) ED1.1.00/02.0109 EU Projects: European Commission(XE) 259796 - DIATOOLS Institutional support: RVO:61389013 Keywords : iron oxide nanoparticle * poly(N,N-dimethylacrylamide-co-acrylic acid) * protein oxidation Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.357, year: 2015

  14. Low-density lipoprotein modified by myeloperoxidase oxidants induces endothelial dysfunction

    DEFF Research Database (Denmark)

    Abdo, Adrian; Rayner, B.S.; van Reyk, D.M.

    2017-01-01

    Low-density lipoprotein (LDL) modified by hypochlorous acid (HOCl) produced by myeloperoxidase (MPO) is present in atherosclerotic lesions, where it is implicated in the propagation of inflammation and acceleration of lesion development by multiple pathways, including the induction of endothelial...

  15. Amperometric detection of Sudan I in red chili powder samples using Ag nanoparticles decorated graphene oxide modified glassy carbon electrode.

    Science.gov (United States)

    Prabakaran, E; Pandian, K

    2015-01-01

    A simple and sensitive electrochemical method was developed to determine the concentration of Sudan I in chili powder based on silver nanoparticles decorated graphene oxide modified glassy carbon electrode (AgNPs@GO/GCE). The voltammetry behaviour of Sudan I on modified GCE was investigated in phosphate buffer medium (PBS) with various pH ranges and the electron transfer properties were studied. It is found that the AgNPs@GO/GCE can catalyse the reduction of azo group, -N=N- followed by electrochemical oxidation of (-)OH group present in Sudan I dye molecule. Quantitative detection of Sudan I present in food products was carried out by amperometry method in which reduction potential was fixed at -0.77 V vs. Ag/AgCl. The amperometry method showed an excellent performance with a sensitivity of 6.83 μA mM(-1) and a detection limit of 11.4 × 10(-7)ML(-1). A linear calibration graph was constructed in the ranging 3.90 × 10(-6) to 3.19 × 10(-5)ML(-1). The method was successfully applied for the determination of Sudan I in red chili powder samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

  16. Electro-oxidation nitrite based on copper calcined layered double hydroxide and gold nanoparticles modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Cui Lin; Meng Xiaomeng; Xu Minrong; Shang Kun; Ai Shiyun; Liu Yinping

    2011-01-01

    Highlights: → A nitrite sensor fabricated based on copper calcined layered double hydroxides and gold nanoparticles modified electrode. → This sensor exhibited excellent electrocatalytic oxidation to nitrite. → This nitrite sensor exhibited very good analytical performance with low cost, convenient preparation and rapid detection. - Abstract: In this paper, a novel nitrite sensor was constructed based on electrodeposition of gold nanoparticles (AuNPs) on a copper calcined layered double hydroxide (Cu-CLDH) modified glassy carbon electrode. Electrochemical experiments showed that AuNPs/CLDH composite film exhibited excellent electrocatalytic oxidation activity with nitrite due to the synergistic effect of the Cu-CLDH with AuNPs. The fabricated sensor exhibited excellent performance for nitrite detection within a wide concentration interval of 1-191 μM and with a detection limit of 0.5 μM. The superior electrocatalytic response to nitrite was mainly attributed to the large surface area, minimized diffusion resistance, and enhanced electron transfer of the Cu-CLDH and AuNPs composition film. This platform offers a novel route for nitrite sensing with wide analytical applications and will supply the practical applications for a variety of simple, robust, and easy-to-manufacture analytical approaches in the future.

  17. Ni modified ceramic anodes for direct-methane solid oxide fuel cells

    Science.gov (United States)

    Xiao, Guoliang; Chen, Fanglin

    2016-01-19

    In accordance with certain embodiments of the present disclosure, a method for fabricating a solid oxide fuel cell is described. The method includes synthesizing a composition having a perovskite present therein. The method further includes applying the composition on an electrolyte support to form an anode and applying Ni to the composition on the anode.

  18. Electrochemical Water Oxidation by a Catalyst-Modified Metal-Organic Framework Thin Film

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Shaoyang; Pineda-Galvan, Yuliana; Maza, William A.; Epley, Charity C.; Zhu, Jie; Kessinger, Matthew C.; Pushkar, Yulia; Morris, Amanda J. (VP); (Purdue)

    2016-12-15

    Water oxidation, a key component in artificial photosynthesis, requires high overpotentials and exhibits slow reaction kinetics that necessitates the use of stable and efficient heterogeneous water-oxidation catalysts (WOCs). Here, we report the synthesis of UiO-67 metal–organic framework (MOF) thin films doped with [Ru(tpy)(dcbpy)OH2]2+ (tpy=2,2':6',2''-terpyridine, dcbpy=5,5'-dicarboxy-2,2'-bipyridine) on conducting surfaces and their propensity for electrochemical water oxidation. The electrocatalyst oxidized water with a turnover frequency (TOF) of (0.2±0.1) s-1 at 1.71 V versus the normal hydrogen electrode (NHE) in buffered solution (pH~7) and exhibited structural and electrochemical stability. The electroactive sites were distributed throughout the MOF thin film on the basis of scan-ratedependent voltammetry studies. This work demonstrates a promising way to immobilize large concentrations of electroactive WOCs into a highly robust MOF scaffold and paves the way for future photoelectrochemical water-splitting systems.

  19. Magnetically-modified natural biogenic iron oxides for organic xenobiotics removal

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Filip, J.; Horská, Kateřina; Nowakova, M.; Tuček, J.; Šafaříková, Miroslava; Hashimoto, H.; Takada, J.; Zbořil, R.

    2015-01-01

    Roč. 12, č. 2 (2015), s. 673-682 ISSN 1735-1472 R&D Projects: GA MŠk(CZ) LH11111; GA MŠk LH12190 Institutional support: RVO:67179843 Keywords : Biogenic iron oxides * Leptothrix ochracea * Magnetic fluid * Magnetic adsorbents * Xenobiotics Subject RIV: EI - Biotechnology ; Bionics Impact factor: 2.344, year: 2015

  20. NADH oxidation on screen-printed electrode modified with a new phenothiazine diazonium salt

    Energy Technology Data Exchange (ETDEWEB)

    Doumeche, Bastien; Blum, Loic J. [GEMBAS, Genie Enzymatique, Membranes Biomimetiques et Assemblages Supramoleculaires, ICBMS UMR 5246, Universite Lyon 1, 43 bd du 11 Novembre 1918, 69622 Villeurbanne (France)

    2010-10-15

    NADH oxidation catalysts are extremely important in the field of electrochemical biosensors and enzymatic biofuel cells. Based on the growing diazonium chemistry, we synthesized the diazonium salt of the well-known NADH mediator toluidine blue O. The electrochemical reduction of the diazonium moiety by cyclic voltammetry onto a screen-printed electrode leads to an electrocatalyst suitable for the oxidation of NADH. The amperometric response for its oxidation shows a maximal current of 1.2 {mu}A ([NADH] = 100 {mu}M). Based on electrochemical measurements, the surface coverage is found to be 3.78 x 10{sup -11} mol cm{sup -2} and the heterogeneous standard rate constant k{sub h} is 1.21 {+-} 0.16 s{sup -1}. The sensitive layer for the oxidation of NADH is improved by electrografting the diazonium salt with a potentiostatic method. Both the surface coverage and the heterogeneous standard rate constant k{sub h} are improved and found to be 6.08 {+-} 0.63 x 10{sup -11} mol cm{sup -2} and {proportional_to} 5.02 s{sup -} {sup 1}, respectively. The amperometric response is also improved by an 8 fold factor, reaching 9.87 {mu}A ([NADH] = 120 {mu}M). These remarkably high values for screen-printed electrodes are comparable to glassy carbon electrodes making this method suitable for low-cost bioelectronical devices. (author)

  1. Assessment of full ceramic solid oxide fuel cells based on modified strontium titanates

    DEFF Research Database (Denmark)

    Holtappels, Peter; Ramos, Tania; Sudireddy, Bhaskar Reddy

    2014-01-01

    stimulated the development for full ceramic anodes based on strontium titanates. Furthermore, the Ni-cermet is primarily a hydrogen oxidation electrode and efficiency losses might occur when operating on carbon containing fuels. In the European project SCOTAS-SOFC full ceramic cells comprising CGO...

  2. Hydrogen peroxide modified Mg-Al-O oxides supported Pt-Sn catalysts for paraffin dehydrogenation

    NARCIS (Netherlands)

    Lai, Y.; He, Songbo; Luo, S.; Bi, W.; Li, XianRu; Sun, Chenglin; Seshan, Kulathuiyer

    2015-01-01

    In this work, a new method to prepare Mg–Al–O oxide by co-precipitation method with addition of H2O2 was developed. The application of Mg–Al–O as a support of Pt–Sn catalysts for paraffin dehydrogenation was investigated. Characterization results indicated that modification of H2O2 (i) enlarged the

  3. Effect of citric acid on formation of oxides of Cu and Zn in modified ...

    Indian Academy of Sciences (India)

    Abstract. We report here the influence of citric acid concentration on the formation of sol-gel products ineach of Cu and Zn systems by using respective metal nitrate as precursor and citric acid as gelling agent. ... At highN:C ratio, lower oxidation state of metal ion is resulted where the metal system is susceptible for reduction.

  4. Leptothrix sp sheaths modified with iron oxide particles: Magnetically responsive, high aspect ratio functional material

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Angelova, R.; Baldíková, E.; Pospíšková, K.; Šafaříková, Miroslava

    2017-01-01

    Roč. 71, February (2017), s. 1342-1346 ISSN 0928-4931 Institutional support: RVO:60077344 Keywords : Leptothrix * magnetic modification * iron oxide * high aspect ratio material Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Material s engineering Impact factor: 4.164, year: 2016

  5. Facile synthesis of reduced graphene oxide-modified, nitrogen-doped carbon xerogel with enhanced electrochemical capacitance

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Gang [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Hu, Xiaoyong [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Peng, Zhiguang [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China); Hu, Jiawen, E-mail: jwhu@hnu.edu.cn [College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082 (China); Liu, Hongtao, E-mail: liuht@csu.edu.cn [College of Chemistry and Chemical Engineering, Central South University, Changsha 410083 (China)

    2014-12-15

    In this contribution, we report a reduced graphene oxide (rGO)-modified nitrogen-doped carbon xerogel, which could be easily prepared by pyrolysis of melamine-formaldehyde (MF) resins that are polymerized hydrothermally in an aqueous GO dispersion. Scanning electron microscopy, transmission electron microscopy, Fourier-transformed infrared spectrometry, and nitrogen adsorption-desorption method were employed to reveal the morphologies and structures of the prepared carbon xerogel. Cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge were used to investigate the electrochemical properties. The results showed that the charge transfer barrier of the mesoporous nitrogen-doped carbon xerogel was decreased evidently, owing to the modification of a layer of rGO on its wall, and the xerogel demonstrated a capacitance of as high as 205 F g{sup −1} at the current of 1 A g{sup −1}. - Graphical abstract: A facile synthesis of rGO-modified, N-doped carbon material for supercapacitor application. - Highlights: • Nitrogen-doping and graphene-attachment in the carbon material are simultaneously achieved. • A thin layer of graphene attached on the wall of the mesoporous carbon material speeds up the charge transfer. • The graphene-modified nitrogen-doped carbon xerogel shows great potential for supercapacitor application.

  6. Control-oriented thermal management of solid oxide fuel cells based on a modified Takagi-Sugeno fuzzy model

    Science.gov (United States)

    Yang, Jie; Li, Xi; Mou, Hong-Gang; Jian, Li

    Thermal management for a solid oxide fuel cell (SOFC) is actually temperature control, due to the importance of cell temperature for the performance of an SOFC. An SOFC stack is a nonlinear and multi-variable system which is difficult to model by traditional methods. A modified Takagi-Sugeno (T-S) fuzzy model that is suitable for nonlinear systems is built to model the SOFC stack. The model parameters are initialized by the fuzzy c-means clustering method, and learned using an off-line back-propagation algorithm. In order to obtain the training data to identify the modified T-S model, a SOFC physical model via MATLAB is established. The temperature model is the center of the physical model and is developed by enthalpy-balance equations. It is shown that the modified T-S fuzzy model is sufficiently accurate to follow the temperature response of the stack, and can be conveniently utilized to design temperature control strategies.

  7. Preparation and characterization of tentacle-type polymer stationary phase modified with graphene oxide for open-tubular capillary electrochromatography.

    Science.gov (United States)

    Gao, Xing; Mo, Rongzhen; Ji, Yibing

    2015-06-26

    In this research, a novel organic polymer coated stationary phase modified with inorganic nanomaterial was prepared for open-tubular capillary electrochromatography (OT-CEC). The capillary was developed by covalent attaching graphene oxide (GO) onto the tentacle-type polymer chains grafted capillary which was derivatized with ammonium hydroxide. Scanning electron microscopy (SEM) and Raman spectroscopy provided evidences that the tentacle-type polymer and GO were coated to the capillary inner wall. This novel GO-polymer modified capillary column generated a strong and stable electroosmotic flow (EOF) from anode to cathode with the running electrolytes of pH ranging from 4.0 to 9.0, and showed excellent separation ability toward neutral small molecules, amino acids and ephedrine-pseudoephedrine isomers with resolution higher than 2.30 and column efficiency up to over 170,000 plates/m. The repeatabilities of the GO-GMA@capillary were satisfying with relative standard deviations for intra-day and inter-day runs less than 3.27%, and column-to-column runs less than 7.49%. Additionally, the separation performance of GO-polymer modified capillary was compared with that of the polymer coated capillary and GO coated capillary. Copyright © 2015 Elsevier B.V. All rights reserved.

  8. Interfacial characterization and supercapacitive properties of polyaniline-Gum arabic nanocomposite/graphene oxide LbL modified electrodes

    Science.gov (United States)

    Oliveira, Rafaela D.; Santos, Cleverson S.; Ferreira, Rodolfo T.; Marciniuk, Gustavo; Marchesi, Luís F.; Garcia, Jarem R.; Vidotti, Marcio; Pessoa, Christiana A.

    2017-12-01

    In this manuscript, we describe the synthesis and electrochemical characterization of polyaniline-gum arabic nanocomposites and graphene oxide (PANI-GA/GO) modified electrodes with a detailed study concerning their supercapacitive properties. The electrode modification was carried out by using the Layer-by-Layer technique (LbL), where the PANI-GA nanocomposite dispersion was used as polycation and the GO colloidal dispersion as polyanion. The bilayer growth was followed by both UV-vis spectroscopy and cyclic voltammetry, and an increase in the characteristic PANI absorption and in the electrochemical signal was verified, confirming the electrode build up. Galvanostatic charge-discharge curves (GCDC) were performed to evaluate the supercapacitive properties of the modified electrodes, these results showed the dependence of the specific capacitance with the number of bilayers, where values of CS around 15 mF cm-2 (i = 0.1 mA cm-2) were found. Electrochemical impedance spectroscopy confirmed the pseudocapacitive properties of the modified electrodes, showing an increase in the low-frequency capacitance with the number of bilayers. Hereby the (PANI-GA/GO)-LbL electrodes were shown to be good candidates for active materials in supercapacitors.

  9. Sol–gel synthesis of tantalum oxide and phosphonic acid-modified carbon nanotubes composite coatings on titanium surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Maho, Anthony [Laboratory of Chemistry and Electrochemistry of Surfaces, University of Namur (FUNDP), Rue de Bruxelles 61, B-5000 Namur (Belgium); Fonds pour la Formation à la Recherche dans l' Industrie et dans l' Agriculture (FRIA), Rue d' Egmont 5, B-1000 Bruxelles (Belgium); Detriche, Simon; Delhalle, Joseph [Laboratory of Chemistry and Electrochemistry of Surfaces, University of Namur (FUNDP), Rue de Bruxelles 61, B-5000 Namur (Belgium); Mekhalif, Zineb, E-mail: zineb.mekhalif@fundp.ac.be [Laboratory of Chemistry and Electrochemistry of Surfaces, University of Namur (FUNDP), Rue de Bruxelles 61, B-5000 Namur (Belgium)

    2013-07-01

    Carbon nanotubes used as fillers in composite materials are more and more appreciated for the outstanding range of accessible properties and functionalities they generate in numerous domains of nanotechnologies. In the framework of biological and medical sciences, and particularly for orthopedic applications and devices (prostheses, implants, surgical instruments, …), titanium substrates covered by tantalum oxide/carbon nanotube composite coatings have proved to constitute interesting and successful platforms for the conception of solid and biocompatible biomaterials inducing the osseous regeneration processes (hydroxyapatite growth, osteoblasts attachment). This paper describes an original strategy for the conception of resistant and homogeneous tantalum oxide/carbon nanotubes layers on titanium through the introduction of carbon nanotubes functionalized by phosphonic acid moieties (-P(=O)(OH){sub 2}). Strong covalent C-P bonds are specifically inserted on their external sidewalls with a ratio of two phosphonic groups per anchoring point. Experimental results highlight the stronger “tantalum capture agent” effect of phosphonic-modified nanotubes during the sol–gel formation process of the deposits compared to nanotubes bearing oxidized functions (-OH, -C=O, -C(=O)OH). Particular attention is also paid to the relative impact of the rate of functionalization and the dispersion degree of the carbon nanotubes in the coatings, as well as their wrapping level by the tantalum oxide matrix material. The resulting effect on the in vitro growth of hydroxyapatite is also evaluated to confirm the primary osseous bioactivity of those materials. Chemical, structural and morphological features of the different composite deposits described herein are assessed by X-ray photoelectron spectroscopy (XPS), scanning (SEM) and transmission (TEM) electronic microscopies, energy dispersive X-rays analysis (EDX) and peeling tests. Highlights: ► Formation of tantalum

  10. Removal of Cd (II in Water Samples Using Modified Magnetic Iron Oxide Nanoparticle

    Directory of Open Access Journals (Sweden)

    Ahmad Kakaei

    2015-11-01

    Full Text Available Background: Heavy metals, even at low concentrations, are harmful to human health and environment. Cadmium as a heavy metal is highly toxic and can cause serious threat to living organisms. This research was designed to evaluate the adsorption potential of modified magnetic iron nanoparticles by 2-(5-bromo-2-pyridylazo-5-diethylaminophenol ligand for the removal of cadmium ions from water solutions. Methods: This study was conducted in Ilam Branch, Islamic Azad University, Iran, in 2014. Modified magnetic iron nanoparticle was used as adsorbent for the removal of cadmium from aqueous solution. In batch extraction, the effects of parameters like pH of sample solution (3.0-11.0, initial metal concentrations (50-300 mgL-1, contact time (1.0-10 min and adsorbent dose (10.0-60.0 mg were studied on the adsorption process. Modified magnetite nanoparticle was presented as the adsorbent for the removal of cadmium ions from aqueous samples and later was confirmed by flame atomic absorption spectrometry. Results: The adsorption of cadmium ions on modified magnetite nanoparticles strongly depends on pH. The experimental isothermal data were analyzed using the Langmuir and Freundlich equations. The removal process followed the Langmuir isotherm. Maximum adsorption capacity for the adsorption of cadmium ions by the sorbent was 24.09 mgg-1. Conclusion: The method was successfully applied to adsorption of cadmium in water samples with satisfactory results. Other advantages include high capacity, good stability and fast adsorption kinetics. High pre-concentration factor was obtained easily by this method (120 and low analysis cost.

  11. Oxidative Stressors Modify the Response of Streptococcus mutans to Its Competence Signal Peptides.

    Science.gov (United States)

    De Furio, Matthew; Ahn, Sang Joon; Burne, Robert A; Hagen, Stephen J

    2017-11-15

    The dental caries pathogen Streptococcus mutans is continually exposed to several types of stress in the oral biofilm environment. Oxidative stress generated by reactive oxygen species has a major impact on the establishment, persistence, and virulence of S. mutans Here, we combined fluorescent reporter-promoter fusions with single-cell imaging to study the effects of reactive oxygen species on activation of genetic competence in S. mutans Exposure to paraquat, which generates superoxide anion, produced a qualitatively different effect on activation of expression of the gene for the master competence regulator, ComX, than did treatment with hydrogen peroxide (H 2 O 2 ), which can yield hydroxyl radical. Paraquat suppressed peptide-mediated induction of comX in a progressive and cumulative fashion, whereas the response to H 2 O 2 displayed a strong threshold behavior. Low concentrations of H 2 O 2 had little effect on induction of comX or the bacteriocin gene cipB , but expression of these genes declined sharply if extracellular H 2 O 2 exceeded a threshold concentration. These effects were not due to decreased reporter gene fluorescence. Two different threshold concentrations were observed in the response to H 2 O 2 , depending on the gene promoter that was analyzed and the pathway by which the competence regulon was stimulated. The results show that paraquat and H 2 O 2 affect the S. mutans competence signaling pathway differently, and that some portions of the competence signaling pathway are more sensitive to oxidative stress than others. IMPORTANCE Streptococcus mutans inhabits the oral biofilm, where it plays an important role in the development of dental caries. Environmental stresses such as oxidative stress influence the growth of S. mutans and its important virulence-associated behaviors, such as genetic competence. S. mutans competence development is a complex behavior that involves two different signaling peptides and can exhibit cell

  12. A study of the electro-catalytic oxidation of methanol on a cobalt hydroxide modified glassy carbon electrode

    International Nuclear Information System (INIS)

    Jafarian, M.; Mahjani, M.G.; Heli, H.; Gobal, F.; Khajehsharifi, H.; Hamedi, M.H.

    2003-01-01

    Cobalt hydroxide modified glassy carbon electrodes (CHM/GC) prepared by the anodic deposition in presence of tartrate ions have been used for the electro-catalytic oxidation of methanol in alkaline solutions where the methods of cyclic voltammetery (CV), chronoamperometry (CA) and impedance spectroscopy (IS) have been employed. In CV studies, in the presence of methanol the peak current of the oxidation of cobalt hydroxide increase is followed by a decrease in the corresponding cathodic current. This suggests that the oxidation of methanol is being catalysed through the mediated electron transfer across the cobalt hydroxide layer comprising of cobalt ions of various valence states. A mechanism based on the electro-chemical generation of Co(IV) active sites and their subsequent consumptions by methanol have been discussed and the corresponding rate law under the control of charge transfer has been developed and kinetic parameters have been derived. In this context the charge transfer resistance accessible both theoretically and through the IS studies have been used as a criteria. Under the CA regimes the reaction followed a Cottrellian behaviour

  13. High activity PtRu/C catalysts synthesized by a modified impregnation method for methanol electro-oxidation

    International Nuclear Information System (INIS)

    Ma Liang; Liu Changpeng; Liao Jianhui; Lu Tianhong; Xing Wei; Zhang Jiujun

    2009-01-01

    A modified impregnation method was used to prepare highly dispersive carbon-supported PtRu catalyst (PtRu/C). Two modifications to the conventional impregnation method were performed: one was to precipitate the precursors ((NH 4 ) 2 PtCl 6 and Ru(OH) 3 ) on the carbon support before metal reduction; the other was to add a buffer into the synthetic solution to stabilize the pH. The prepared catalyst showed a much higher activity for methanol electro-oxidation than a catalyst prepared by the conventional impregnation method, even higher than that of current commercially available, state-of-the-art catalysts. The morphology of the prepared catalyst was characterized using TEM and XRD measurements to determine particle sizes, alloying degree, and lattice parameters. Electrochemical methods were also used to ascertain the electrochemical active surface area and the specific activity of the catalyst. Based on XPS measurements, the high activity of this catalyst was found to originate from both metallic Ru (Ru 0 ) and hydrous ruthenium oxides (RuO x H y ) species on the catalyst surface. However, RuO x H y was found to be more active than metallic Ru. In addition, the anhydrous ruthenium oxide (RuO 2 ) species on the catalyst surface was found to be less active.

  14. Samarium-modified vanadium phosphate catalyst for the selective oxidation of n-butane to maleic anhydride

    International Nuclear Information System (INIS)

    Wu, Hua-Yi; Wang, Hai-Bo; Liu, Xin-Hua; Li, Jian-Hui; Yang, Mei-Hua; Huang, Chuan-Jing; Weng, Wei-Zheng; Wan, Hui-Lin

    2015-01-01

    Graphical abstract: The addition of a small amount of Sm into VPO catalyst brought about great changes in its physicochemical properties such as surface area, surface morphology, phase composition and redox property, thus leading to a higher catalytic performance in the selective oxidation of n-butane to maleic anhydride, as compared to the undoped VPO catalyst. - Highlights: • The addition of Sm leads to great changes in the structure of VPO catalyst. • Sm improves performance of VPO for oxidation of n-butane to maleic anhydride. • Catalytic performance is closely related to structure of VPO catalyst. - Abstract: A series of samarium-modified vanadium phosphate catalysts were prepared and studied in selective oxidation of n-butane to maleic anhydride. The catalytic evaluation showed that Sm modification significantly increased the overall n-butane conversion and intrinsic activity. N 2 -adsorption, XRD, SEM, Raman, XPS, EPR and H 2 -TPR techniques were used to investigate the intrinsic difference among these catalysts. The results revealed that the addition of Sm to VPO catalyst can increase the surface area of the catalyst, lead to a significant change in catalyst morphology from plate-like structure into rosette-shape clusters, and largely promote the formation of (VO) 2 P 2 O 7 . All of these were related to the different catalytic performance of Sm-doped and undoped VPO catalysts. The roles of the different VOPO 4 phases and the influence of Sm were also described and discussed

  15. Direct Synthesis of Methanol by Partial Oxidation of Methane with Oxygen over Cobalt Modified Mesoporous H-ZSM-5 Catalyst

    Directory of Open Access Journals (Sweden)

    Yuni Krisyuningsih Krisnandi

    2015-11-01

    Full Text Available Partial oxidation of methane over mesoporous catalyst cobalt modified H-ZSM-5 has been carried out. Mesoporous Na-ZSM-5 (Si/Al = 35.4 was successfully synthesized using double template method which has high surface area (450 m2/g and average pore diameter distribution of 1.9 nm. The as-synthesized Na-ZSM-5 was converted to H-ZSM-5 through multi-exchange treatment with ammonium ion solution, causing decreased crystallinity and surface area, but increased porous diameter, due to dealumination during treatment process. Moreover, H-ZSM-5 was loaded with cobalt (Co = 2.5% w by the incipient impregnation method and calcined at 550 °C. Partial oxidation of methane was performed in the batch reactor with 0.75 bar methane and 2 bar of nitrogen (with impurities of 0.5% oxygen as the input at various reaction time (30, 60 and 120 min. The reaction results show that cobalt species in catalyst has an important role, because H-ZSM-5 cannot produce methanol in partial oxidation of methane. The presence of molecular oxygen increased the percentage of methanol yield. The reaction is time-dependent with the highest methanol yield (79% was acquired using Co/H-ZSM-5 catalyst for 60 min.

  16. Electrocatalytic Oxidation of Hydrogen Peroxide Based on the Shuttlelike Nano-CuO-Modified Electrode

    Directory of Open Access Journals (Sweden)

    Geng Yang

    2012-01-01

    Full Text Available CuO nanocrystals were prepared with hydrothermal synthesis method. The morphology of the nano-CuO was characterized by scanning electron microscopy. The prepared shuttlelike CuO nanocrystals were modified to glass carbon electrode (GCE to form nano-CuO/GCE modified electrode. The obtained modified electrode showed an excellent electrocatalytic property towards hydrogen peroxide in 0.01 M NaOH containing 0.09 M KCl electrolyte. Under the optimal experiment conditions, the electrocatalytic response current of this sensor was proportional to the H2O2 concentration in the range of 0.02 μM~250 μM with a detection limit down to 7 nM (signal/noise = 3. The sensitivity was calculated to be 227 μA/mM. The H2O2 sensor exhibited low detection limit, fast response time, and good reproducibility and could be applied to determine hydrogen peroxide.

  17. Sulfur-Modified Graphitic Carbon Nitride Nanostructures as an Efficient Electrocatalyst for Water Oxidation.

    Science.gov (United States)

    Kale, Vinayak S; Sim, Uk; Yang, Jiwoong; Jin, Kyoungsuk; Chae, Sue In; Chang, Woo Je; Sinha, Arun Kumar; Ha, Heonjin; Hwang, Chan-Cuk; An, Junghyun; Hong, Hyo-Ki; Lee, Zonghoon; Nam, Ki Tae; Hyeon, Taeghwan

    2017-05-01

    There is an urgent need to develop metal-free, low cost, durable, and highly efficient catalysts for industrially important oxygen evolution reactions. Inspired by natural geodes, unique melamine nanogeodes are successfully synthesized using hydrothermal process. Sulfur-modified graphitic carbon nitride (S-modified g-CN x ) electrocatalysts are obtained by annealing these melamine nanogeodes in situ with sulfur. The sulfur modification in the g-CN x structure leads to excellent oxygen evolution reaction activity by lowering the overpotential. Compared with the previously reported nonmetallic systems and well-established metallic catalysts, the S-modified g-CN x nanostructures show superior performance, requiring a lower overpotential (290 mV) to achieve a current density of 10 mA cm -2 and a Tafel slope of 120 mV dec -1 with long-term durability of 91.2% retention for 18 h. These inexpensive, environmentally friendly, and easy-to-synthesize catalysts with extraordinary performance will have a high impact in the field of oxygen evolution reaction electrocatalysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. SURFACE-MODIFIED FERRITIC INTERCONNECT MATERIALS FOR SOLID OXIDE FUEL CELLS

    Energy Technology Data Exchange (ETDEWEB)

    Bruce R. Lanning; James Arps; Ronghua Wei; Goeff Dearnaley

    2004-03-15

    Interconnects are a critical element of an SOFC assembly and although much work has focused on chromium and chromium-iron alloys containing an oxide that is both oxidation resistant and electrically conductive, the thermal instability of typical native metal oxides allow interdiffusion of cations across the interconnect-electrode boundary that ultimately leads to degradation of SOFC performance. Phase I of the SECA Core Technology Program has been a one-year effort to investigate and evaluate the feasibility of: (1) Ion implanting an alumina-scale forming ferritic steel, such as FeCrAlY, to form an interconnect material with low resistance (< 0.1 {Omega}/cm{sup 2}) in oxidizing/reducing environments up to 800 C, and (2) Maintaining the above low resistance metric for an extended time (> 1000 hours at 800 C) in contact with an LSF cathode material. We confirmed, as part of our oxidation kinetics evaluation of FeCrAlY and 430 ferritic steel, the parabolic growth of a mixed chromia/alumina scale on FeCrAlY and a single chromia layer in the case of the 430 stainless steel; the outer contiguous layer of Al{sub 2}O{sub 3}, in the case of FeCrAlY, forming a stable, self-limiting, protective scale with no detectable cation interdiffusion between FeCrAlY and an LSF electrode even after 1000 hours at 800 C in air. To render the alumina scale conductive, we implanted either titanium or niobium ions into FeCrAlY scales to a fixed depth (0.12 {micro}m), varying only the thickness of the oxide. ASR for an un-doped FeCrAlY oxide scale (i.e., alumina) was more than an order of magnitude greater than the 430 control sample whereas, the ASR for the doped FeCrAlY oxide scale sample was comparable to the 430 control sample; hence, the resistance of a doped alumina scale on FeCrAlY was equal to the resistance of a chromia-scale forming alloy, such as 430 (chromia scales of which are typically < 0.1 {Omega}-cm). Along with the ASR measurements, AC impedance measurements were conducted

  19. Graphene oxide modified with PMMA via ATRP as a reinforcement filler

    OpenAIRE

    Gonçalves, Gil; Marques, Paula A. A. P.; Barros-Timmons, Ana; Bdikin, Igor; Singh, Manoj K.; Emami, Nazanin; Grácio, José

    2010-01-01

    Graphene is a two-dimensional new allotrope of carbon, which is stimulating great curiosity due to its superior mechanical, electrical, thermal and optical properties. Particularly attractive is the availability of bulk quantities of graphene (G) which can be easily processed by chemical exfoliation, yielding graphene oxide (GO). The resultant oxygenated graphene sheets covered with hydroxyl, epoxy and carboxyl groups offer tremendous opportunities for further functionalization opening plenty...

  20. Effect of graphene oxide on structure and properties of impact-modified polyamide 6

    Czech Academy of Sciences Publication Activity Database

    Kelnar, Ivan; Kratochvíl, Jaroslav; Kaprálková, Ludmila; Špitálsky, Z.; Ujčić, Massimo; Zhigunov, Alexander; Nevoralová, Martina

    2018-01-01

    Roč. 57, č. 9 (2018), s. 827-835 ISSN 0360-2559 R&D Projects: GA ČR(CZ) GA16-03194S Institutional support: RVO:61389013 Keywords : graphene oxide * morphology * polyamide 6 Subject RIV: JI - Composite Materials OBOR OECD: Composites (including laminates, reinforced plastics, cermets, combined natural and synthetic fibre fabrics Impact factor: 1.232, year: 2016

  1. Leptothrix sp sheaths modified with iron oxide particles: Magnetically responsive, high aspect ratio functional material

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Angelova, R.; Baldíková, Eva; Pospišková, K.; Šafaříková, Miroslava

    2017-01-01

    Roč. 71, FEB (2017), s. 1342-1346 ISSN 0928-4931 R&D Projects: GA ČR(CZ) GA14-11516S; GA MŠk(CZ) LD14075 Institutional support: RVO:67179843 Keywords : removal * Leptothrix * Magnetic modification * Iron oxide * High aspect ratio material Subject RIV: EI - Biotechnology ; Bionics OBOR OECD: Environmental science s (social aspects to be 5.7) Impact factor: 4.164, year: 2016

  2. Elevated oxidative membrane damage associated with genetic modifiers of Lyst-mutant phenotypes.

    Directory of Open Access Journals (Sweden)

    Colleen M Trantow

    2010-07-01

    Full Text Available LYST is a large cytosolic protein that influences the biogenesis of lysosome-related organelles, and mutation of the encoding gene, LYST, can cause Chediak-Higashi syndrome. Recently, Lyst-mutant mice were recognized to also exhibit an iris disease resembling exfoliation syndrome, a common cause of glaucoma in humans. Here, Lyst-mutant iris phenotypes were used in a search for genes that influence Lyst pathways. In a candidate gene-driven approach, albino Lyst-mutant mice homozygous for a mutation in Tyr, whose product is key to melanin synthesis within melanosomes, exhibited complete rescue of Lyst-mutant iris phenotypes. In a genetic background-driven approach using a DBA/2J strain of congenic mice, an interval containing Tyrp1 enhanced Lyst-dependent iris phenotypes. Thus, both experimental approaches implicated the melanosome, an organelle that is a potential source of oxidative stress, as contributing to the disease phenotype. Confirming an association with oxidative damage, Lyst mutation resulted in genetic context-sensitive changes in iris lipid hydroperoxide levels, being lowest in albino and highest in DBA/2J mice. Surprisingly, the DBA/2J genetic background also exposed a late-onset neurodegenerative phenotype involving cerebellar Purkinje-cell degeneration. These results identify an association between oxidative damage to lipid membranes and the severity of Lyst-mutant phenotypes, revealing a new mechanism that contributes to pathophysiology involving LYST.

  3. RGO modified Ni doped FeOOH for enhanced electrochemical and photoelectrochemical water oxidation

    Science.gov (United States)

    Zhang, Xiaofan; Zhang, Bingyan; Liu, Shuangshuang; Kang, Hongwei; Kong, Weiqian; Zhang, Shouren; Shen, Yan; Yang, Baocheng

    2018-04-01

    Ni,Fe-based (oxy)hydroxides have been one of the most active catalysts for the oxygen evolution reaction. In this article, reduced graphene oxide supported Ni doped FeOOH (RGO/Ni:FeOOH) was prepared for electrochemical and photoelectrochemical (PEC) water oxidation. The RGO/Ni:FeOOH exhibited a lower over-potential (260 mV at 10 mA cm-2) and smaller Tafel slope (32.3 mV dec-1) than that of the FeOOH and Ni:FeOOH. Such significant enhancement is attributed to Ni doping and RGO, which reduce the over-potential, improve the conductivity and enlarge surface areas. Besides, RGO/Ni:FeOOH decorated the TiO2 nanorods (NRs) was also fabricated for photoelectrochemical (PEC) water oxidation, which exhibited a higher photocurrent density and lower onset potential than that of TiO2 NRs the bare under illumination due to the synergistic effect of RGO and Ni:FeOOH. These results demonstrate the RGO/Ni:FeOOH has great promising as a co-catalyst to improve the PEC performance.

  4. Conjugated polymer covalently modified graphene oxide quantum dots for ternary electronic memory devices.

    Science.gov (United States)

    Fan, Fei; Zhang, Bin; Cao, Yaming; Yang, Xutong; Gu, Junwei; Chen, Yu

    2017-08-03

    Zero dimensional graphene oxide (GO) quantum dots (GOQDs) have been expected to play an important role in the development of new memory materials. When the size of GO was reduced to that of GOQDs, both the electron affinity and ionization potential of GO were found to be decreased, and this was followed by the elevation of lowest energy unoccupied molecular orbital (LUMO) energy level. This implies that the electron withdrawing ability of GOQDs is weaker than that of GO. In this work, a novel arylamine-based polyazomethine covalently functionalized graphene oxide quantum dots (TPAPAM-GOQDs), which was synthesized using an amidation reaction, was for the first time used to fabricate a ternary memory device with a configuration of gold/TPAPAM-GOQDs/indium tin oxide. The current ratio of OFF : ON-1 : ON-2 was found to be 1 : 60 : 3000. Its conductive nature was also revealed using an in situ conductive atomic force microscopy technique. This memory device could potentially increase the memory capacity of the device from the conventional 2 n to 3 n when compared to binary memory devices.

  5. Oxidative Polyoxometalates Modified Graphitic Carbon Nitride for Visible-Light CO2Reduction.

    Science.gov (United States)

    Zhou, Jie; Chen, Weichao; Sun, Chunyi; Han, Lu; Qin, Chao; Chen, Mengmeng; Wang, Xinlong; Wang, Enbo; Su, Zhongmin

    2017-04-05

    Developing a photocatalysis system for converting CO 2 to valuable fuels or chemicals is a promising strategy to address global warming and fossil fuel consumption. Exploring photocatalysts with high-performance and low-cost has been two ultimate goals toward photoreduction of CO 2 . Herein, noble-metal-free polyoxometalates (Co4) with oxidative ability was first introduced into g-C 3 N 4 resulted in inexpensive hybrid materials (Co4@g-C 3 N 4 ) with staggered band alignment. The staggered composited materials show a higher activity of CO 2 reduction than bare g-C 3 N 4 . An optimized Co4@g-C 3 N 4 hybrid sample exhibited a high yield (107 μmol g -1 h -1 ) under visible-light irradiation (λ ≥ 420 nm), meanwhile maintaining high selectivity for CO production (94%). After 10 h of irradiation, the production of CO reached 896 μmol g -1 . Mechanistic studies revealed the introduction of Co4 not only facilitate the charge transfer of g-C 3 N 4 but greatly increased the surface catalytic oxidative ability. This work creatively combined g-C 3 N 4 with oxidative polyoxometalates which provide novel insights into the design of low-cost photocatalytic materials for CO 2 reduction.

  6. Covalent immobilization of invertase on PAMAM-dendrimer modified superparamagnetic iron oxide nanoparticles

    International Nuclear Information System (INIS)

    Uzun, K.; Cevik, E.; Senel, M.; Soezeri, H.; Baykal, A.; Abasiyanik, M. F.; Toprak, M. S.

    2010-01-01

    In this study, polyamidoamine (PAMAM) dendrimer was synthesized on the surface of superparamagnetite nanoparticles to enhance invertase immobilization. The amount of immobilized enzyme on the surface-hyperbranched magnetite nanoparticle was up to 2.5 times (i.e., 250%) as much as that of magnetite nanoparticle modified with only amino silane. Maximum reaction rate (V max ) and Michaelis-Menten constant (K m ) were determined for the free and immobilized enzymes. Various characteristics of immobilized invertase such as; the temperature activity, thermal stability, operational stability, and storage stability were evaluated and results revealed that stability of the enzyme is improved upon immobilization.

  7. Modified Ta/MCM-41 catalysts for enantioselective oxidation of thioanisole

    OpenAIRE

    Fadhli, Marwa; Khedher, Ilyes; Fraile, José M.

    2015-01-01

    Ta-MCM41 catalysts have been prepared by grafting of Ta(OEt)5 on MCM41, pre-calcined at three different temperatures (550, 650 and 750 °C). These solids have been modified with two chiral ligands: R-(+)-diethyl l-tartrate (DET) and R-(+)-diisopropyl l-tartrate (DIPT). The formation of the chiral tantalum species and their influence on the structure of MCM41 have been studied by several characterization techniques, such as XRD, FTIR, N2 adsorption isotherms and MAS NMR. The grafted tantalum sp...

  8. Preparation of surface modified zinc oxide nanoparticle with high capacity dye removal ability

    International Nuclear Information System (INIS)

    Mahmoodi, Niyaz Mohammad; Najafi, Farhood

    2012-01-01

    Highlights: ► Amine-functionalized zinc oxide nanoparticle (AFZON) was synthesized. ► Isotherm and kinetics data followed Langmuir isotherm and pseudo-second order kinetic model, respectively. ► Q 0 of ZON for AB25, DR23 and DR31 was 20, 12 and 15 mg/g, respectively. ► Q 0 of AFZON for AB25, DR23 and DR31 was 1250, 1000 and 1429 mg/g, respectively. ► AFZON was regenerated at pH 12. -- Abstract: In this paper, the surface modification of zinc oxide nanoparticle (ZON) by amine functionalization was studied to prepare high capacity adsorbent. Dye removal ability of amine-functionalized zinc oxide nanoparticle (AFZON) and zinc oxide nanoparticle (ZON) was also investigated. The physical characteristics of AFZON were studied using Fourier transform infrared (FTIR), scanning electron microscopy (SEM) and X-ray diffraction (XRD). Acid Blue 25 (AB25), Direct Red 23 (DR23) and Direct Red 31 (DR31) were used as model compounds. The effect of operational parameters such as dye concentration, adsorbent dosage, pH and salt on dye removal was evaluated. The isotherm and kinetic of dye adsorption were studied. The maximum dye adsorption capacity (Q 0 ) was 20 mg/g AB25, 12 mg/g DR23 and 15 mg/g DR31 for ZON and 1250 mg/g AB25, 1000 mg/g DR23 and 1429 mg/g DR31 for AFZON. It was found that dye adsorption followed Langmuir isotherm. Adsorption kinetic of dyes was found to conform to pseudo-second order kinetics. Dye desorption tests (adsorbent regeneration) showed that the maximum dye release of 90% AB25, 86% for DR23 and 90% for DR31 were achieved in aqueous solution at pH 12. Based on the data of the present investigation, it can be concluded that the AFZON being an adsorbent with high dye adsorption capacity might be a suitable alternative to remove dyes from colored aqueous solutions.

  9. Poly(L-lysine)-modified iron oxide nanoparticles for stem cell labeling

    Czech Academy of Sciences Publication Activity Database

    Babič, Michal; Horák, Daniel; Trchová, Miroslava; Jendelová, Pavla; Růžičková, Kateřina; Lesný, Petr; Herynek, V.; Hájek, M.; Syková, Eva

    2008-01-01

    Roč. 19, č. 3 (2008), s. 740-750 ISSN 1043-1802 R&D Projects: GA AV ČR KAN200200651; GA AV ČR KAN201110651; GA ČR GA203/05/2256; GA ČR(CZ) GA309/06/1594; GA MŠk 1M0538 Institutional research plan: CEZ:AV0Z40500505; CEZ:AV0Z50390703 Keywords : iron oxide * magnetic * nanoparticles Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.584, year: 2008

  10. Fabrication of a solution-gated transistor based on valinomycin modified iron oxide nanoparticles decorated zinc oxide nanorods for potassium detection.

    Science.gov (United States)

    Ahn, Min-Sang; Ahmad, Rafiq; Bhat, Kiesar Sideeq; Yoo, Jin-Young; Mahmoudi, Tahmineh; Hahn, Yoon-Bong

    2018-05-15

    There are considerable interests to detect and monitor the abnormal level of minerals in water for avoiding/preventing any toxic effects after consumption. Herein, we report the fabrication of solution-gated field-effect-transistor (FET) based potassium sensor using iron oxide nanoparticles (Fe 2 O 3 NPs) modified directly grown zinc oxide nanorods (ZnO NRs). The Fe 2 O 3 NPs modification of ZnO NRs provided stability to nanorods surface and improved surface area for valinomycin immobilization. As-fabricated potassium sensor (valinomycin-Fe 2 O 3 NPs-ZnO NRs/SiO 2 /Si) provided enhanced current response with increasing potassium concentration. During sensing measurements, FET sensor showed high sensitivity (4.65 μA/μM/cm 2 ) in the linear range of 0.1 μM to 125 μM, low limit of detection (∼0.04 μM), good stability, excellent reproducibility, and favorable selectivity. Thus, good sensing performance of the FET based potassium sensor presents it as simple, low-cost, and convenient device for selective detection of potassium in solution. Copyright © 2018 Elsevier Inc. All rights reserved.

  11. Synthesis of modified calcium aluminate with lanthanum manganite (LSM) for possible use in solid oxide fuel cell (SOFC)

    International Nuclear Information System (INIS)

    Veiga, F.C.T.; Jurado, J.; Sousa, V.C. de

    2016-01-01

    The fuel cells solid oxide (SOFC) is made up of three basic elements: two electrodes, the anode and cathode and a conductive electrolyte ions. The objective of this work consists of calcium aluminate synthesis modified LSM in a 1: 1 by combustion synthesis method with a view to its use as a cathode in SOFC. The characterization of the post was carried out by the methods of XRD, TEM and EIS. After heat treatment at 1200°C/4 hours it was possible to obtain Ca0.5Sr1.5MnO4 and CaMnO2.56 phases. The material showed a semiconductor characteristics because with increasing temperature the electrical resistance value tends to decrease obtaining electrical conductivity greater than 10-6S / cm featuring an extrinsic semiconductor with an activation energy of 0.12. Therefore, with an activation energy value within the range of materials used for a SOFC cathodes. (author)

  12. One pot in situ growth of gold nanoparticles on amine-modified graphene oxide and their high catalytic properties

    Science.gov (United States)

    Ju, Yuyun; Li, Xi; Feng, Jie; Ma, Yanhua; Hu, Jing; Chen, Xingguo

    2014-10-01

    In this work, one pot strategy was proposed for in situ growth of Au nanoparticles (Au NPs) on the surface of amine-modified graphene oxide (GO@NH2) nanosheets. Au NPs were generated via an in situ reduction of Au3+ by Cu+ which was linked to the surface of GO@NH2 nanosheets through inorganic grafting. The initial Au NPs then served as seed for subsequent particle growth. The as-obtained GO@NH2-Au nanocomposites (GO@NH2-Au NCs) exhibited high catalytic activity for the degradation of 4-nitrophenol, which was a refractory pollutant that occur in industrial waste water. The catalytic efficiency was examined by turnover frequency (TOF). It was calculated to be 595 h-1, which was higher than that of other Au catalysts. Furthermore, the as-prepared catalyst showed high cycle stabilization during the catalytic reduction.

  13. An Electrochemical Enzyme Biosensor for 3-Hydroxybutyrate Detection Using Screen-Printed Electrodes Modified by Reduced Graphene Oxide and Thionine

    Directory of Open Access Journals (Sweden)

    Gonzalo Martínez-García

    2017-11-01

    Full Text Available A biosensor for 3-hydroxybutyrate (3-HB involving immobilization of the enzyme 3-hydroxybutyrate dehydrogenase onto a screen-printed carbon electrode modified with reduced graphene oxide (GO and thionine (THI is reported here. After addition of 3-hydroxybutyrate or the sample in the presence of NAD+ cofactor, the generated NADH could be detected amperometrically at 0.0 V vs. Ag pseudo reference electrode. Under the optimized experimental conditions, a calibration plot for 3-HB was constructed showing a wide linear range between 0.010 and 0.400 mM 3-HB which covers the clinically relevant levels for diluted serum samples. In addition, a limit of detection of 1.0 µM, much lower than that reported using other biosensors, was achieved. The analytical usefulness of the developed biosensor was demonstrated via application to spiked serum samples.

  14. Effect of Zinc Oxide Modified Silica Particles on the Molecular Dynamics of Carboxylated Acrylonitrile-Butadiene Rubber Composites

    Directory of Open Access Journals (Sweden)

    Magdalena Gaca

    2017-11-01

    Full Text Available This work examines the molecular dynamics of carboxylated acrylonitrile-butadiene rubber crosslinked with zinc oxide modified silica particles. ZnO/SiO2 with the wide range of ZnO concentrations were used as both a crosslinking agent and filler. A series of thermal measurements were applied to the characterization of the samples: differential scanning calorimetry, dynamical mechanical thermal analysis, and dielectric relaxation spectroscopy. A complementary experimental technique, which is equilibrium swelling in solvents, confirms the presence of ionic crosslinks, which are created between zinc ions and the functional carboxyl groups of the rubber, within the structure of the vulcanizates. These interactions influenced not only the affinity of the vulcanizates to solvents, but also their dynamic mechanical and dielectric properties. In these investigations, the influence of concentration of ZnO on the surface of the ZnO/SiO2 on the properties of the vulcanizates are described.

  15. A Promising Combo Gene Delivery System Developed from (3-Aminopropyl)triethoxysilane-Modified Iron Oxide Nanoparticles and Cationic Polymers

    International Nuclear Information System (INIS)

    Zhang Zubin; Song Lina; Dong Jinlai; Guo Dawei; Du Xiaolin; Cao Biyin; Zhang Yu; Gu Ning; Mao Xinliang

    2013-01-01

    (3-Aminopropyl)triethoxysilane-modified iron oxide nanoparticles (APTES-IONPs) have been evaluated for various biomedical applications, including medical imaging and drug delivery. Cationic polymers (CPs) such as Lipofectamine and TurboFect are widely used for research in gene delivery, but their toxicity and low in vivo efficiency limited their further application. In the present study, we synthesized water-soluble APTES-IONPs and developed a combo gene delivery system based on APTES-IONPs and CPs. This system significantly increased gene-binding capacity, protected genes from degradation, and improved gene transfection efficiency for DNA and siRNA in both adherent and suspension cells. Because of its great biocompatibility, high gene-carrying ability, and very low cytotoxicity, this combo gene delivery system will be expected for a wide application, and it might provide a new method for gene therapy.

  16. Physicochemically modified peat by thermal and oxidation processes as an active material for purification of wastewaters from certain hazardous pollutants

    Directory of Open Access Journals (Sweden)

    Purenović Jelena M.

    2017-01-01

    Full Text Available The physicochemical modification of peat through thermal and oxidation processes was carried out, in order to obtain new, inexpensive and active material for purification of different types of waters. During the modification, surface chemical compounds of Shilov type were formed. Batch adsorption properties and suitability of physicochemically modified peat (PCMP for odor removal were tested in aqueous solutions of H2S and colloidal sulphur. Additionally, PCMP was tested in the removal of As(V which is hazardous ingredient in contaminated waters. Possible mechanisms of pollutants binding include interactions, which lead to formation of adducts and clathrates. All these processes are elucidated in detail. The results showed that the obtained material can be used for the removal of sulphide, colloidal sulphur and As(V from different types of waters. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 45012

  17. A Promising Combo Gene Delivery System Developed from (3-Aminopropyl)triethoxysilane-Modified Iron Oxide Nanoparticles and Cationic Polymers

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zubin [Soochow University, Cyrus Tang Hematology Center (China); Song Lina; Dong Jinlai; Guo Dawei [School of Biological Science and Medical Engineering, Southeast University, State Key Laboratory of Bioelectronics and Jiangsu Key Laboratory for Biomaterials and Devices (China); Du Xiaolin; Cao Biyin [Soochow University, Cyrus Tang Hematology Center (China); Zhang Yu; Gu Ning [School of Biological Science and Medical Engineering, Southeast University, State Key Laboratory of Bioelectronics and Jiangsu Key Laboratory for Biomaterials and Devices (China); Mao Xinliang, E-mail: xinliangmao@suda.edu.cn [Soochow University, Cyrus Tang Hematology Center (China)

    2013-05-15

    (3-Aminopropyl)triethoxysilane-modified iron oxide nanoparticles (APTES-IONPs) have been evaluated for various biomedical applications, including medical imaging and drug delivery. Cationic polymers (CPs) such as Lipofectamine and TurboFect are widely used for research in gene delivery, but their toxicity and low in vivo efficiency limited their further application. In the present study, we synthesized water-soluble APTES-IONPs and developed a combo gene delivery system based on APTES-IONPs and CPs. This system significantly increased gene-binding capacity, protected genes from degradation, and improved gene transfection efficiency for DNA and siRNA in both adherent and suspension cells. Because of its great biocompatibility, high gene-carrying ability, and very low cytotoxicity, this combo gene delivery system will be expected for a wide application, and it might provide a new method for gene therapy.

  18. High temperature oxidation behavior of gamma-nickel+gamma'-nickel aluminum alloys and coatings modified with platinum and reactive elements

    Science.gov (United States)

    Mu, Nan

    Materials for high-pressure turbine blades must be able to operate in the high-temperature gases (above 1000°C) emerging from the combustion chamber. Accordingly, the development of nickel-based superalloys has been constantly motivated by the need to have improved engine efficiency, reliability and service lifetime under the harsh conditions imposed by the turbine environment. However, the melting point of nickel (1455°C) provides a natural ceiling for the temperature capability of nickel-based superalloys. Thus, surface-engineered turbine components with modified diffusion coatings and overlay coatings are used. Theses coatings are capable of forming a compact and adherent oxide scale, which greatly impedes the further transport of reactants between the high-temperature gases and the underlying metal and thus reducing attack by the atmosphere. Typically, these coatings contain beta-NiAl as a principal constituent phase in order to have sufficient aluminum content to form an Al2O3 scale at elevated temperatures. The drawbacks to the currently-used beta-based coatings, such as phase instabilities, associated stresses induced by such phase instabilities, and extensive coating/substrate interdiffusion, are major motivations in this study to seek next-generation coatings. The high-temperature oxidation resistance of novel Pt+Hf-modified gamma-Ni+gamma'-Ni 3Al-based alloys and coatings were investigated in this study. Both early-stage and 4-days isothermal oxidation behavior of single-phase gamma-Ni and gamma'-Ni3Al alloys were assessed by examining the weight changes, oxide-scale structures, and elemental concentration profiles through the scales and subsurface alloy regions. It was found that Pt promotes Al 2O3 formation by suppressing the NiO growth on both gamma-Ni and gamma'-Ni3Al single-phase alloys. This effect increases with increasing Pt content. Moreover, Pt exhibits this effect even at lower temperatures (˜970°C) in the very early stage of oxidation. It

  19. Modified polarographic method of determining O/U ratio of uranium oxide-based nuclear fuels

    International Nuclear Information System (INIS)

    Papez, V.; Vecernik, J.; Krtil, J.

    1983-01-01

    Following the dissolution of UO 2 in concentrated H 3 PO 4 the solution contains not only U(VI) but also a large excess of U(IV). The polarographic method was used to determine the concentration of U(VI) in the initial sample. Then an accurate amount of cerium sulphate was added to the sample. Part of the U(VI) was converted into U(VI) which was again determined using polarography. The remaining U(IV) was determined by amperometrical titration in the same sample using Ce(SO 4 ) 2 . This method makes po-sible a simple and quick determination of the O/U ratio in uranium oxides. It is suitable for routine analyses and may be performed on routine polarographical instruments. (E.S.)

  20. Visual and spectrophotometric determination of mercury(II) using silver nanoparticles modified with graphene oxide

    International Nuclear Information System (INIS)

    Noor, An’amt Mohamed; Rameshkumar, Perumal; Huang, Nay Ming; Wei, Lee Seong

    2016-01-01

    The authors describe the ultrasound-assisted synthesis of a graphene oxide-silver (GO-Ag) nanocomposite for the determination of mercury(II) (Hg(II)) using spectrophotometry. The nanocomposite was characterized by UV-visible absorption spectra, XRD, TEM and Raman analyses. The spectral and colorimetric methods were performed for the optical determination of Hg(II). The reduction of absorption intensity with blue shift in the absorption band of Ag nanoparticles and the color change of the yellow nanocomposite solution were observed during the determination of Hg(II). The limit of detection was found to be 0.59 μM. The GO-Ag nanocomposite exhibited good selectivity toward the determination of Hg(II) in the presence of higher concentration of other environmentally relevant heavy metal ions. (author)

  1. Selective side-chain oxidation of alkyl aromatic compounds catalyzed by cerium modified silver catalysts

    DEFF Research Database (Denmark)

    Beier, Matthias Josef; Schimmoeller, Bjoern; Hansen, Thomas Willum

    2010-01-01

    . In addition, flame-made catalysts were more stable against silver leaching compared to the impregnated catalysts. The structure of the silver catalysts was studied in detail both by X-ray absorption spectroscopy and transmission electron microscopy suggesting metallic silver to be required for catalytic......Silver supported on silica effectively catalyzes the aerobic side-chain oxidation of alkyl aromatic compounds under solvent-free conditions. Toluene, p-xylene, ethylbenzene and cumene were investigated as model substrates. Typically, the reaction was performed at ambient pressure; only for toluene...... an elevated pressure was required. Carboxylic acids, such as benzoic acid or p-toluic acid, additionally increased the reaction rate while CeO2 could act both as a promoter and an inhibitor depending on the substrate and the reaction conditions. Silver catalysts were prepared both by standard impregnation...

  2. Electrocatalytic miRNA Detection Using Cobalt Porphyrin-Modified Reduced Graphene Oxide

    Directory of Open Access Journals (Sweden)

    Camille De Souza

    2014-06-01

    Full Text Available Metalated porphyrins have been described to bind nucleic acids. Additionally, cobalt porphyrins present catalytic properties towards oxygen reduction. In this work, a carboxylic acid-functionalized cobalt porphyrin was physisorbed on reduced graphene oxide, then immobilized on glassy carbon electrodes. The carboxylic groups were used to covalently graft amino-terminated oligonucleotide probes which are complementary to a short microRNA target. It was shown that the catalytic oxygen electroreduction on cobalt porphyrin increases upon hybridization of miRNA strand (“signal-on” response. Current changes are amplified compared to non-catalytic amperometric system. Apart from oxygen, no added reagent is necessary. A limit of detection in the sub-nanomolar range was reached. This approach has never been described in the literature.

  3. Surface and bulk modified high capacity layered oxide cathodes with low irreversible capacity loss

    Science.gov (United States)

    Manthiram, Arumugam (Inventor); Wu, Yan (Inventor)

    2010-01-01

    The present invention includes compositions, surface and bulk modifications, and methods of making of (1-x)Li[Li.sub.1/3Mn.sub.2/3]O.sub.2.xLi[Mn.sub.0.5-yNi.sub.0.5-yCo.sub.2- y]O.sub.2 cathode materials having an O3 crystal structure with a x value between 0 and 1 and y value between 0 and 0.5, reducing the irreversible capacity loss in the first cycle by surface modification with oxides and bulk modification with cationic and anionic substitutions, and increasing the reversible capacity to close to the theoretical value of insertion/extraction of one lithium per transition metal ion (250-300 mAh/g).

  4. The modeling and simulation of thermal based modified solid oxide fuel cell (SOFC for grid-connected systems

    Directory of Open Access Journals (Sweden)

    Ayetül Gelen

    2015-05-01

    Full Text Available This paper presents a thermal based modified dynamic model of a Solid Oxide Fuel Cell (SOFC for grid-connected systems. The proposed fuel cell model involves ohmic, activation and concentration voltage losses, thermal dynamics, methanol reformer, fuel utilization factor and power limiting module. A power conditioning unit (PCU, which consists of a DC-DC boost converter and a DC-AC voltage-source inverter (VSI, their controller, transformer and filter, is designed for grid-connected systems. The voltage-source inverter with six Insulated Gate Bipolar Transistor (IGBT switches inverts the DC voltage that comes from the converter into a sinusoidal voltage synchronized with the grid. The simulations and modeling of the system are developed on Matlab/Simulink environment. The performance of SOFC with converter is examined under step and random load conditions. The simulation results show that the designed boost converter for the proposed thermal based modified SOFC model has fairly followed different DC load variations. Finally, the AC bus of 400 Volt and 50 Hz is connected to a single-machine infinite bus (SMIB through a transmission line. The real and reactive power managements of the inverter are analyzed by an infinite bus system. Thus, the desired nominal values are properly obtained by means of the inverter controller.

  5. A new partial SOI-LDMOSFET with a modified buried oxide layer for improving self-heating and breakdown voltage

    International Nuclear Information System (INIS)

    Jamali Mahabadi, S E; Orouji, Ali A; Keshavarzi, P; Moghadam, Hamid Amini

    2011-01-01

    In this paper, for the first time, we propose a partial silicon-on-insulator (P-SOI) lateral double-diffused metal-oxide-semiconductor-field-effect-transistor (LDMOSFET) with a modified buried layer in order to improve breakdown voltage (BV) and self-heating effects (SHEs). The main idea of this work is to control the electric field by shaping the buried layer. With two steps introduced in the buried layer, the electric field distribution is modified. Also a P-type window introduced makes the substrate share the vertical voltage drop, leading to a high vertical BV. Moreover, four interface electric field peaks are introduced by the buried P-layer, the Si window and two steps, which modulate the electric field in the SOI layer and the substrate. Hence, a more uniform electric field is obtained; consequently, a high BV is achieved. Furthermore, the Si window creates a conduction path between the active layer and substrate and alleviates the SHE. Two-dimensional simulations show that the BV of double step partial silicon on insulator is nearly 69% higher and alleviates SHEs 17% in comparison with its single step partial SOI counterpart and nearly 265% higher and alleviate SHEs 18% in comparison with its conventional SOI counterpart

  6. Direct electrochemistry and electrocatalysis of glucose oxidase immobilized on reduced graphene oxide and silver nanoparticles nanocomposite modified electrode.

    Science.gov (United States)

    Palanisamy, Selvakumar; Karuppiah, Chelladurai; Chen, Shen-Ming

    2014-02-01

    The direct electrochemistry of glucose oxidase (GOx) was successfully realized on electrochemically reduced graphene oxide and silver nanoparticles (RGO/Ag) nanocomposite modified electrode. The fabricated nanocomposite was characterized by field emission scanning electron microscope and energy dispersive spectroscopy. The GOx immobilized nanocomposite modified electrode showed a pair of well-defined redox peaks with a formal potential (E°) of -0.422 V, indicating that the bioactivity of GOx was retained. The heterogeneous electron transfer rate constant (Ks) of GOx at the nanocomposite was calculated to be 5.27 s(-1), revealing a fast direct electron transfer of GOx. The GOx immobilized RGO/Ag nanocomposite electrode exhibited a good electrocatalytic activity toward glucose over a linear concentration range from 0.5 to 12.5 mM with a detection limit of 0.16 mM. Besides, the fabricated biosensor showed an acceptable sensitivity and selectivity for glucose. Copyright © 2013 Elsevier B.V. All rights reserved.

  7. Preparation of graphene oxide doped eggshell membrane bioplatform modified Prussian blue nanoparticles as a sensitive hydrogen peroxide sensor.

    Science.gov (United States)

    Mohammad-Rezaei, Rahim; Razmi, Habib; Dehgan-Reyhan, Sajjad

    2014-06-01

    This study describes the preparation and characterization of graphene oxide doped eggshell membrane (GO-ESM) as a novel electrochemical bioplatform for electroanalytical purposes. The GO-ESM bioplatform was prepared by incorporation of GO nano-sheets into the ESM via a facile sonication procedure. Field emission scanning electron microscopy and X-ray diffraction powder techniques were used to characterize the developed bioplatform. The electrochemistry of GO-ESM was investigated by decorating it on the surface of carbon ceramic electrode (CCE) by an O-ring. The GO-ESM platform was modified with Prussian blue (PB) via a facile dip-coating method. Then the resulted modified electrode (PB|GO-ESM|CCE) was used as a novel hydrogen peroxide electrochemical sensor. The fabricated electrode responds efficiently to H2O2 over the concentration range 125nM-195μM with a detection limit of 31nM (S/N=3) and sensitivity 8.8μAμM(-1)cm(-2). The PB|GO-ESM|CCE has been successfully applied to determination of H2O2 content in spiked milk samples. Due to good stability, environmental friendly, cheapness, nontoxic, well behaved electrochemical properties, and biocompatibility, the fabricated bioplatform has the promising future for practical applications. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Degradation of phenylamine by catalytic wet air oxidation using metal catalysts with modified supports.

    Science.gov (United States)

    Torrellas, Silvia A; Escudero, Gabriel O; Rodriguez, Araceli R; Rodriguez, Juan G

    2015-01-01

    The effect of acid treatments with HCl and HNO3 on the surface area and surface chemistry of three granular activated carbons was studied. These supports were characterized and the hydrochloric acid treatment leads to the best activated carbon support (AC2-C). The catalytic behavior of Pt, Ru and Fe (1 wt.%) supported on granular activated carbon treated with HCl was tested in the phenylamine continuous catalytic wet air oxidation in a three-phase, high-pressure catalytic reactor over a range of reaction temperatures 130-170ºC and total pressure of 1.0-3.0 MPa at LHSV = 0.4-1 h(-1), whereas the phenylamine concentration range and the catalyst loading were 5-16 mol.m(-3) and 0.5-1.5 g, respectively. Activity as well as conversion varied as a function of the metal, the catalyst preparation method and operation conditions. Higher activities were obtained with Pt incorporated on hydrochloric acid -treated activated carbon by the ion exchange method. In steady state, approximately 98% phenylamine conversion, 77% of TOC and 94% of COD removal, was recorded at 150ºC, 11 mol m(-3) of phenylamine concentration and 1.5 g of catalyst, and the selectivity to non-organic compounds was 78%. Several reaction intermediaries were detected. A Langmuir-Hinshelwood model gave an excellent fit of the kinetic data of phenylamine continuous catalytic wet air oxidation over the catalysts of this work.

  9. Kinetics of carbon monoxide oxidation over modified supported CuO catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Loc, Luu Cam; Tri, Nguyen; Cuong, Hoang Tien; Thoang, Ho Si [Vietnam Academy of Science and Technology (VAST), Ho Chi Minh City (Viet Nam). Inst. of Chemical Technology; Agafonov, Yu.A.; Gaidai, N.A.; Lapidus, A.L. [Russian Academy of Sciences, Moscow (Russian Federation). N.D. Zelinsky Institute of Organic Chemistry

    2013-11-01

    The following supported on {gamma}-Al{sub 2}O{sub 3} catalysts: 10(wt.)%CuO (CuAl), 10%CuO+10%Cr{sub 2}O{sub 3} (CuCrAl) and 10%CuO+20%CeO{sub 2} (CuCeAl) were under the investigation. Physico-chemical characteristics of the catalysts were determined by the methods of BET, X-ray Diffraction (XRD), and Temperature-Programmed Reduction (TPR). A strong interaction of copper with support in CuAl resulted in the formation of low active copper aluminates. The bi-oxide CuCrAl was more active than CuAl owing to the formation of high catalytically active spinel CuCr{sub 2}O{sub 4}. The fact of very high activity of the sample CuCeAl can be explained by the presence of the catalytically active form of CuO-CeO{sub 2}-Al{sub 2}O{sub 3}. The kinetics of CO total oxidation was studied in a gradientless flow-circulating system at the temperature range between 200 C and 270 C. The values of initial partial pressures of carbon monoxide (P{sup o}{sub CO}), oxygen (P{sup o}{sub O2}), and specially added carbon dioxide (P{sup o}{sub CO{sub 2}}) were varied in ranges (hPa): 10 / 45; 33 / 100, and 0 / 30, respectively. (orig.)

  10. Synthesis and Characterization of Ferrocene Derivatives and Preliminarily Electrocatalytic Oxidation of L-Cysteine at Nafion-Ferrocene Derivatives Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Jianping Yong

    2014-01-01

    Full Text Available Five new structural ferrocene derivatives (2a~2e were firstly synthesized and characterized by 1H NMR, 13C NMR, ESI-MS, and XRD. Subsequently, the preliminarily electrocatalytic oxidation of L-cysteine (L-Cys at nafion-ferrocene derivatives modified glassy carbon electrode (GCE has also been investigated by cyclic voltammetry. The results showed that 2e can dramatically electrocatalyze the oxidation of L-cysteine at its modified GCE in 0.1 mol L−1 NaNO3 aqueous solution with a quasireversible process with ΔEp≈55 mV.

  11. Direct electrochemical oxidation of S-captopril using gold electrodes modified with graphene-AuAg nanocomposites

    Science.gov (United States)

    Pogacean, Florina; Biris, Alexandru R; Coros, Maria; Lazar, Mihaela Diana; Watanabe, Fumiya; Kannarpady, Ganesh K; Al Said, Said A Farha; Biris, Alexandru S; Pruneanu, Stela

    2014-01-01

    In this paper, we present a novel approach for the electrochemical detection of S-captopril based on graphene AuAg nanostructures used to modify an Au electrode. Multi-layer graphene (Gr) sheets decorated with embedded bimetallic AuAg nanoparticles were successfully synthesized catalytically with methane as the carbon source. The two catalytic systems contained 1.0 wt% Ag and 1.0 wt% Au, while the second had a larger concentration of metals (1.5 wt% Ag and 1.5 wt% Au) and was used for the synthesis of the Gr-AuAg-1 and Gr-AuAg-1.5 multicomponent samples. High-resolution transmission electron microscopy analysis indicated the presence of graphene flakes that had regular shapes (square or rectangular) and dimensions in the tens to hundreds of nanometers. We found that the size of the embedded AuAg nanoparticles varied between 5 and 100 nm, with the majority being smaller than 20 nm. Advanced scanning transmission electron microscopy studies indicated a bimetallic characteristic of the metallic clusters. The resulting Gr-AuAg-1 and Gr-AuAg-1.5 samples were used to modify the surface of commonly used Au substrates and subsequently employed for the direct electrochemical oxidation of S-captopril. By comparing the differential pulse voltammograms recorded with the two modified electrodes at various concentrations of captopril, the peak current was determined to be well-defined, even at relatively low concentration (10−5 M), for the Au/Gr-AuAg-1.5 electrode. In contrast, the signals recorded with the Au/Gr-AuAg-1 electrode were poorly defined within a 5×10−6 to 5×10−3 M concentration range, and many of them overlapped with the background. Such composite materials could find significant applications in nanotechnology, sensing, or nanomedicine. PMID:24596464

  12. The relationship of the anti-oxidant bilirubin with free thyroxine is modified by insulin resistance in euthyroid subjects.

    Directory of Open Access Journals (Sweden)

    Petronella E Deetman

    Full Text Available BACKGROUND: The strong anti-oxidative properties of bilirubin largely explain its cardioprotective effects. Insulin resistance is featured by low circulating bilirubin. Thyroid hormone affects both bilirubin generation and its biliary transport, but it is unknown whether circulating bilirubin is associated with thyroid function in euthyroid subjects. Aim is to determine relationships of bilirubin with TSH, free T4 and free T3 in euthyroid subjects without type 2 diabetes mellitus (T2DM, and to assess whether such a relationship would be modified by the degree of insulin resistance. METHODS: Total bilirubin, TSH, free T4, free T3, glucose, insulin, lipids and transaminases were measured in 1854 fasting euthyroid subjects without T2DM, recruited from the general population (PREVEND cohort. Insulin resistance was assessed by homeostasis model assessment. RESULTS: Bilirubin was positively related to free T4 (β = 0.116, P<0.001 and free T3 (β = 0.078, P = 0.001, but bilirubin was unrelated to TSH. The relationship of bilirubin with free T4 was modified by insulin resistance with a larger effect in more insulin resistant individuals (adjusted for age and sex: β = 0.043, P = 0.056 for interaction; additionally adjusted for smoking, alcohol intake, transaminases and total cholesterol (β = 0.044, P = 0.044 for interaction. The association of bilirubin with free T4 was also modified by high density lipoprotein cholesterol (age- and sex-adjusted: β = 0.040, P = 0.072. CONCLUSIONS: Low bilirubin relates to low free T4 in euthyroid non-diabetic subjects. Low normal free T4 may particularly confer low bilirubin in more insulin resistant individuals.

  13. The utilization of SiNWs/AuNPs-modified indium tin oxide (ITO) in fabrication of electrochemical DNA sensor

    International Nuclear Information System (INIS)

    Rashid, Jahwarhar Izuan Abdul; Yusof, Nor Azah; Abdullah, Jaafar; Hashim, Uda; Hajian, Reza

    2014-01-01

    This work describes the incorporation of SiNWs/AuNPs composite as a sensing material for DNA detection on indium tin-oxide (ITO) coated glass slide. The morphology of SiNWs/AuNPs composite as the modifier layer on ITO was studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The morphological studies clearly showed that SiNWs were successfully decorated with 20 nm-AuNPs using self-assembly monolayer (SAM) technique. The effective surface area for SiNWs/AuNPs-modified ITO enhanced about 10 times compared with bare ITO electrode. SiNWs/AuNPs nanocomposite was further explored as a matrix for DNA probe immobilization in detection of dengue virus as a bio-sensing model to evaluate its performance in electrochemical sensors. The hybridization of complementary DNA was monitored by differential pulse voltammetry (DPV) using methylene blue (MB) as the redox indicator. The fabricated biosensor was able to discriminate significantly complementary, non-complementary and single-base mismatch oligonucleotides. The electrochemical biosensor was sensitive to target DNA related to dengue virus in the range of 9.0–178.0 ng/ml with detection limit of 3.5 ng/ml. In addition, SiNWs/AuNPs-modified ITO, regenerated up to 8 times and its stability was up to 10 weeks at 4 °C in silica gel. - Highlights: • A sensitive biosensor is presented for detection of dengue virus. • SiNWs and AuNPs used as nanocomposite layers on ITO for construction of biosensor • The detection mechanism is based on the interaction of MB with DNA bonded on AuNPs. • The reduction signal of MB decreases upon complementary hybridization

  14. The utilization of SiNWs/AuNPs-modified indium tin oxide (ITO) in fabrication of electrochemical DNA sensor

    Energy Technology Data Exchange (ETDEWEB)

    Rashid, Jahwarhar Izuan Abdul [Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Department of Chemistry and Biology, Centre for Defense Foundation Studies, National Defense University of Malaysia, Sungai Besi Camp, 57000 Kuala Lumpur (Malaysia); Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Yusof, Nor Azah, E-mail: azahy@upm.edu.my [Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Abdullah, Jaafar [Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Hashim, Uda [Institute of Nanoelectronic Engineering, Universiti Malaysia Perlis, 01000 Kangar, Perlis (Malaysia); Hajian, Reza, E-mail: rezahajian@upm.edu.my [Institute of Advanced Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia)

    2014-12-01

    This work describes the incorporation of SiNWs/AuNPs composite as a sensing material for DNA detection on indium tin-oxide (ITO) coated glass slide. The morphology of SiNWs/AuNPs composite as the modifier layer on ITO was studied by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). The morphological studies clearly showed that SiNWs were successfully decorated with 20 nm-AuNPs using self-assembly monolayer (SAM) technique. The effective surface area for SiNWs/AuNPs-modified ITO enhanced about 10 times compared with bare ITO electrode. SiNWs/AuNPs nanocomposite was further explored as a matrix for DNA probe immobilization in detection of dengue virus as a bio-sensing model to evaluate its performance in electrochemical sensors. The hybridization of complementary DNA was monitored by differential pulse voltammetry (DPV) using methylene blue (MB) as the redox indicator. The fabricated biosensor was able to discriminate significantly complementary, non-complementary and single-base mismatch oligonucleotides. The electrochemical biosensor was sensitive to target DNA related to dengue virus in the range of 9.0–178.0 ng/ml with detection limit of 3.5 ng/ml. In addition, SiNWs/AuNPs-modified ITO, regenerated up to 8 times and its stability was up to 10 weeks at 4 °C in silica gel. - Highlights: • A sensitive biosensor is presented for detection of dengue virus. • SiNWs and AuNPs used as nanocomposite layers on ITO for construction of biosensor • The detection mechanism is based on the interaction of MB with DNA bonded on AuNPs. • The reduction signal of MB decreases upon complementary hybridization.

  15. Electro-oxidation of some non-steroidal anti-inflammatory drugs on an alumina nanoparticle-modified glassy carbon electrode

    OpenAIRE

    TABESHNIA, Mahla; HELI, Hossein; JABBARI, Ali

    2010-01-01

    The electro-oxidation of mefenamic acid, diclofenac, and indomethacin on glassy carbon and alumina nanoparticle-modified glassy carbon electrodes in a phosphate buffer solution at physiological pH was studied. The techniques of cyclic voltammetry, chronoamperometry, impedance spectroscopy, and steady state polarization measurements were applied. The drugs were irreversibly oxidized on bath electrodes via an anodic peak and the process was controlled by diffusion in the bulk of soluti...

  16. Aging Impairs Myocardial Fatty Acid and Ketone Oxidation and Modifies Cardiac Functional and Metabolic Responses to Insulin in Mice

    Energy Technology Data Exchange (ETDEWEB)

    Hyyti, Outi M.; Ledee, Dolena; Ning, Xue-Han; Ge, Ming; Portman, Michael A.

    2010-07-02

    Aging presumably initiates shifts in substrate oxidation mediated in part by changes in insulin sensitivity. Similar shifts occur with cardiac hypertrophy and may contribute to contractile dysfunction. We tested the hypothesis that aging modifies substrate utilization and alters insulin sensitivity in mouse heart when provided multiple substrates. In vivo cardiac function was measured with microtipped pressure transducers in the left ventricle from control (4–6 mo) and aged (22–24 mo) mice. Cardiac function was also measured in isolated working hearts along with substrate and anaplerotic fractional contributions to the citric acid cycle (CAC) by using perfusate containing 13C-labeled free fatty acids (FFA), acetoacetate, lactate, and unlabeled glucose. Stroke volume and cardiac output were diminished in aged mice in vivo, but pressure development was preserved. Systolic and diastolic functions were maintained in aged isolated hearts. Insulin prompted an increase in systolic function in aged hearts, resulting in an increase in cardiac efficiency. FFA and ketone flux were present but were markedly impaired in aged hearts. These changes in myocardial substrate utilization corresponded to alterations in circulating lipids, thyroid hormone, and reductions in protein expression for peroxisome proliferator-activated receptor (PPAR)α and pyruvate dehydrogenase kinase (PDK)4. Insulin further suppressed FFA oxidation in the aged. Insulin stimulation of anaplerosis in control hearts was absent in the aged. The aged heart shows metabolic plasticity by accessing multiple substrates to maintain function. However, fatty acid oxidation capacity is limited. Impaired insulin-stimulated anaplerosis may contribute to elevated cardiac efficiency, but may also limit response to acute stress through depletion of CAC intermediates.

  17. Arsanilic acid modified superparamagnetic iron oxide nanoparticles for Purification of alkaline phosphatase from hen's egg yolk.

    Science.gov (United States)

    Farzi-Khajeh, Hamed; Safa, Kazem D; Dastmalchi, Siavoush

    2017-09-01

    Recent studies of magnetic carrier technology have focused on its applications in separation and purification technologies, due to easy separation of the target from the reaction medium by applying an external magnetic field. In the present study, Fe 3 O 4 superparamagnetic nanoparticles were prepared to utilize a chemical co-precipitation method, then the surfaces of the nanoparticles were modified with arsanilic acid derivatives which were used as the specific nanocarriers for the affinity purification of alkaline phosphatase from the hen's egg yolk. The six different types of magnetic nanocarriers with varied lengths of the linkers were obtained. All samples were characterized step by step and validated using FTIR, SEM, EDX, VSM and XRD analysis methods As the results were shown, the use of inflexible tags with long linkers on the surface of the nanocarrier could lead to better results for separation of alkaline phosphatase from the hen's egg yolk with 76.2% recovery and 1361.7-fold purification. The molecular weight of the purified alkaline phosphatase was estimated to be 68kDa by SDS-PAGE. The results of this study showed that the novel magnetic nanocarriers were capable of purifying alkaline phosphatase in a practically time and cost effective way. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Selective catalytic reduction of nitrogen oxides over a modified silicoaluminophosphate commercial zeolite.

    Science.gov (United States)

    Petitto, Carolina; Delahay, Gérard

    2018-03-01

    Nitrogen oxides (NO x : NO, NO 2 ) are a concern due to their adverse health effects. Diesel engine transport sector is the major emitter of NO x . The regulations have been strengthened and to comply with them, one of the two methods commonly used is the selective catalytic reduction of NO x by NH 3 (NH 3 -SCR), NH 3 being supplied by the in-situ hydrolysis of urea. Efficiency and durability of the catalyst for this process are highly required. Durability is evaluated by hydrothermal treatment of the catalysts at temperature above 800°C. In this study, very active catalysts for the NH 3 -SCR of NO x were prepared by using a silicoaluminophosphate commercial zeolite as copper host structure. Characterizations by X-ray diffraction (XRD), scanning electron microscopy (SEM) and temperature programmed desorption of ammonia (NH 3 -TPD) showed that this commercial zeolite was hydrothermally stable up to 850°C and, was able to retain some structural properties up to 950°C. After hydrothermal treatment at 850°C, the NO x reduction efficiency into NH 3 -SCR depends on the copper content. The catalyst with a copper content of 1.25wt.% was the most active. The difference in activity was much more important when using NO than the fast NO/NO 2 reaction mixture. Copyright © 2017. Published by Elsevier B.V.

  19. Electrocatalytic Oxidation of Formate with Nickel Diphosphane Dipeptide Complexes. Effect of Ligands Modified with Amino Acids

    Energy Technology Data Exchange (ETDEWEB)

    Galan, Brandon R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Reback, Matthew L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jain, Avijita [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Appel, Aaron M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Shaw, Wendy J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2013-09-03

    A series of nickel bis-diphosphine complexes with dipeptides appended to the ligands were investigated for the catalytic oxidation of formate. Typical rates of ~7 s-1 were found, similar to the parent complex (~8 s-1), with amino acid size and positioning contributing very little to rate or operating potential. Hydroxyl functionalities did result in lower rates, which were recovered by protecting the hydroxyl group. The results suggest that the overall dielectric introduced by the dipeptides does not play an important role in catalysis, but free hydroxyl groups do influence activity suggesting contributions from intra- or intermolecular interactions. These observations are important in developing a fundamental understanding of the affect that an enzyme-like outer coordination sphere can have upon molecular catalysts. This work was funded by the US DOE Basic Energy Sciences, Chemical Sciences, Geoscience and Biosciences Division (BRG, AJ, AMA, WJS), the US DOE Basic Energy Sciences, Physical Bioscience program (MLR). Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy.

  20. A Modified Fluorimetric Method for Determination of Hydrogen Peroxide Using Homovanillic Acid Oxidation Principle

    Directory of Open Access Journals (Sweden)

    Biswaranjan Paital

    2014-01-01

    Full Text Available Hydrogen peroxide (H2O2 level in biological samples is used as an important index in various studies. Quantification of H2O2 level in tissue fractions in presence of H2O2 metabolizing enzymes may always provide an incorrect result. A modification is proposed for the spectrofluorimetric determination of H2O2 in homovanillic acid (HVA oxidation method. The modification was included to precipitate biological samples with cold trichloroacetic acid (TCA, 5% w/v followed by its neutralization with K2HPO4 before the fluorimetric estimation of H2O2 is performed. TCA was used to precipitate the protein portions contained in the tissue fractions. After employing the above modification, it was observed that H2O2 content in tissue samples was ≥2 fold higher than the content observed in unmodified method. Minimum 2 h incubation of samples in reaction mixture was required for completion of the reaction. The stability of the HVA dimer as reaction product was found to be >12 h. The method was validated by using known concentrations of H2O2 and catalase enzyme that quenches H2O2 as substrate. This method can be used efficiently to determine more accurate tissue H2O2 level without using internal standard and multiple samples can be processed at a time with additional low cost reagents such as TCA and K2HPO4.

  1. Graphene oxide modified light addressable potentiometric sensor and its application for ssDNA monitoring.

    Science.gov (United States)

    Jia, Yunfang; Yin, Xue-Bo; Zhang, Jia; Zhou, Shuang; Song, Meng; Xing, Ke-Li

    2012-12-21

    A light addressable potentiometric sensor (LAPS) is a kind of silicon based semiconductor sensor, and surface modification is a fundamental problem for its application in biological fields. Graphene oxide (GO) based biochemically activated LAPS were proposed, called GO-LAPS. The GO-LAPS were applied to monitoring single strand DNA (ssDNA) probe immobilization and its hybridization with complementary ssDNA molecules of different chain lengths (30, 21 and 14 base pairs, respectively). It was discovered that the curves of LAPS' currents versus analyte concentrations for ssDNA probe binding and the target ssDNA hybridization were different. Explanations were proposed based on the semiconductor's surface-electric-field-effect and the electrical properties of ssDNA molecule. Moreover, comparisons between GO-LAPS and LAPS without GO modification were carried out. Enhanced response currents of GO-LAPS were reported experimentally and analyzed theoretically based on X-ray photoelectron spectroscopy (XPS) of GO-LAPS. The limitation of target ssDNA monitoring was 1 pM to 10 nM, which suggested that this LAPS based platform could be developed as a sensitive means for short chain ssDNA detection.

  2. Hydroxyapatite formation on graphene oxide modified with amino acids: arginine versus glutamic acid.

    Science.gov (United States)

    Tavafoghi, M; Brodusch, N; Gauvin, R; Cerruti, M

    2016-01-01

    Hydroxyapatite (HA, Ca5(PO4)3OH) is the main inorganic component of hard tissues, such as bone and dentine. HA nucleation involves a set of negatively charged phosphorylated proteins known as non-collagenous proteins (NCPs). These proteins attract Ca(2+) and PO4(3-) ions and increase the local supersaturation to a level required for HA precipitation. Polar and charged amino acids (AAs) are highly expressed in NCPs, and seem to be responsible for the mineralizing effect of NCPs; however, the individual effect of these AAs on HA mineralization is still unclear. In this work, we investigate the effect of a negatively charged (Glu) and positively charged (Arg) AA bound to carboxylated graphene oxide (CGO) on HA mineralization in simulated body fluids (SBF). Our results show that Arg induces HA precipitation faster and in larger amounts than Glu. We attribute this to the higher stability of the complexes formed between Arg and Ca(2+) and PO4(3-) ions, and also to the fact that Arg exposes both carboxyl and amino groups on the surface. These can electrostatically attract both Ca(2+) and PO4(3-) ions, thus increasing local supersaturation more than Glu, which exposes carboxyl groups only. © 2016 The Author(s).

  3. Hydroxyapatite formation on graphene oxide modified with amino acids: arginine versus glutamic acid

    Science.gov (United States)

    Tavafoghi, M.; Brodusch, N.; Gauvin, R.; Cerruti, M.

    2016-01-01

    Hydroxyapatite (HA, Ca5(PO4)3OH) is the main inorganic component of hard tissues, such as bone and dentine. HA nucleation involves a set of negatively charged phosphorylated proteins known as non-collagenous proteins (NCPs). These proteins attract Ca2+ and PO43− ions and increase the local supersaturation to a level required for HA precipitation. Polar and charged amino acids (AAs) are highly expressed in NCPs, and seem to be responsible for the mineralizing effect of NCPs; however, the individual effect of these AAs on HA mineralization is still unclear. In this work, we investigate the effect of a negatively charged (Glu) and positively charged (Arg) AA bound to carboxylated graphene oxide (CGO) on HA mineralization in simulated body fluids (SBF). Our results show that Arg induces HA precipitation faster and in larger amounts than Glu. We attribute this to the higher stability of the complexes formed between Arg and Ca2+ and PO43− ions, and also to the fact that Arg exposes both carboxyl and amino groups on the surface. These can electrostatically attract both Ca2+ and PO43− ions, thus increasing local supersaturation more than Glu, which exposes carboxyl groups only. PMID:26791001

  4. Electrochemical Impedance and Polarization Corrosion Studies of Tantalum Surface Modified by DC Plasma Electrolytic Oxidation

    Directory of Open Access Journals (Sweden)

    Maciej Sowa

    2018-04-01

    Full Text Available Tantalum has recently become an actively researched biomaterial for the bone reconstruction applications because of its excellent corrosion resistance and successful clinical records. However, a bare Ta surface is not capable of directly bonding to the bone upon implantation and requires some method of bioactivation. In this study, this was realized by direct current (DC plasma electrolytic oxidation (PEO. Susceptibility to corrosion is a major factor determining the service-life of an implant. Therefore, herein, the corrosion resistance of the PEO coatings on Ta was investigated in Ringer’s solution. The coatings were formed by galvanostatic anodization up to 200, 300 and 400 V, after which the treatment was conducted potentiostatically until the total process time amounted to 5 min. Three solutions containing Ca(H2PO22, Ca(HCOO2 and Mg(CH3COO2 were used in the treatment. For the corrosion characterization, electrochemical impedance spectroscopy and potentiodynamic polarization techniques were chosen. The coatings showed the best corrosion resistance at voltages low enough so that the intensive sparking was absent, which resulted in the formation of thin films. The impedance data were fitted to the equivalent electrical circuits with two time constants, namely R(Q[R(QR] and R(Q[R(Q[RW

  5. [Sorption characteristics of tea waste modified by hydrated ferric oxide toward Pb(II) in water].

    Science.gov (United States)

    Wan, Shun-Li; Xue, Yao; Ma, Zhao-Zhao; Liu, Guo-Bin; Yu, Yan-Xia; Ma, Ming-Hai

    2014-10-01

    Hydrated ferric oxide was successfully impregnated onto tea waste by precipitation to obtain a new sorbent named HFO-TW, the adsorption characteristics of which toward Pb(II) in aqueous solution was investigated by evaluating the effects of pH value, contact time, coexisting ion, temperature, and initial concentration of Pb(II). The Pb(II) sorption onto HFO-TW was pH- dependent, and the higher pH value was more helpful for Pb(II) adsorption onto HFO-TW in the pH range of 2.5-7. Lead sorption speed was quick and could reach equilibrium within 100 min, and the kinetics curve could be fitted well by both pseudo-first and pseudo-second models. The related coefficient was 98.8%. HFO-TW exhibited highly selective lead retention and the adsorption capacity of Pb(II) onto HFO-TW was declined by only 12.1 mg · g(-1) and 8.1 mg · g(-1) in the presence of competing Ca(II), Mg(II) at 50 times of the target ion. In addition, Pb(II) sorption onto HFO-TW could be described satisfactorily by Langmuir model, and the maximal sorption capacity calculated by Langmuir equation was 89.43 mg · g(-1), which was much higher than the unmodified tea waste and other bio-sorbents. All the results validated that HFO-TW was a promising sorbent for removal of lead from waters.

  6. Enhanced selective response to nitric oxide (NO) of Au-modified tungsten trioxide nanoplates

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Li [School of Materials Science and Engineering, Zhengzhou University, 100 Science Road, Zhengzhou 450001 (China); Chen, Deliang, E-mail: dlchen@zzu.edu.cn [School of Materials Science and Engineering, Zhengzhou University, 100 Science Road, Zhengzhou 450001 (China); UK–China Centre for Multi-functional Nanomaterials, Zhengzhou University, Zhengzhou 450001 (China); Fan, Bingbing; Lu, Hongxia; Wang, Hailong; Xu, Hongliang; Yang, Daoyuan [School of Materials Science and Engineering, Zhengzhou University, 100 Science Road, Zhengzhou 450001 (China); Shao, Guosheng [UK–China Centre for Multi-functional Nanomaterials, Zhengzhou University, Zhengzhou 450001 (China); Institute for Renewable Energy and Environmental Technology, University of Bolton, Bolton BL3 5AB (United Kingdom); Zhang, Rui, E-mail: zhangray@zzu.edu.cn [School of Materials Science and Engineering, Zhengzhou University, 100 Science Road, Zhengzhou 450001 (China); Laboratory of Aeronautical Composites, Zhengzhou Institute of Aeronautical Industry Management, University Centre, Zhengdong New District, Zhengzhou 450046 (China)

    2013-12-16

    Au-modified WO{sub 3} nanoplates (Au@plate-WO{sub 3}) were synthesized by chemically reducing HAuCl{sub 4} on the surfaces of two-dimensional WO{sub 3} nanoplates, which were derived from an intercalation–topochemical process. XRD, SEM, TEM, XPS and UV–vis DR spectra were used to characterize the WO{sub 3} nanoplates and Au@plate-WO{sub 3} nanocomposites. The gas-sensing properties of the WO{sub 3} nanoplates and Au@plate-WO{sub 3} nanocomposites were comparatively investigated using inorganic gases and organic vapors as the target gases, with an emphasis on exploring the response and selectivity of NO gases with low concentrations (0.5–10 ppm) at low operating temperature (130−250 °C). The results indicated that Au nanoparticles (Au NPs) enhance the low-temperature sensitivity and selectivity of the Au@plate-WO{sub 3} sensors for NO detection when compared with the performance of the WO{sub 3} sensors. The Au@plate-WO{sub 3} nanocomposite with 1 wt.% Au NPs has the best NO-sensing performance at the optimum operating temperature of ∼170 °C. In addition, the Au@plate-WO{sub 3} sensors show highly selective to NO gas among various inorganic gases (i.e., H{sub 2}, SO{sub 2} and CO) and organic vapors (i.e., alcohol, acetone, methanal and benzene). The enhancement in sensitivity and selectivity for NO detection is probably due to the synergistic effect of Au NPs and the house-of-card structure of WO{sub 3} nanoplates. - Highlights: • Au@plate-WO{sub 3} nanocomposites were synthesized by a chemical process. • The Au@plate-WO{sub 3} sensors were highly selective to NO gases with low concentrations. • The Au@plate-WO{sub 3} sensors had the highest sensitivity operating at about 170 °C. • The optimum amount of Au nanoparticles was about 1 wt.%. • Au nanoparticles and the loose aggregates enhanced the NO-sensing performance.

  7. Nitric oxide modifies chromatin to suppress ICAM-1 expression during colonic inflammation.

    Science.gov (United States)

    Li, Qingjie; Sarna, Sushil K

    2012-07-01

    Nitric oxide (NO) is an established inflammatory mediator. However, it remains controversial whether NO enhances the inflammatory response in the colon or suppresses it. We investigated the epigenetic regulation of Icam-1 expression by NO following induction of colonic inflammation in rats by 2,4,6-trinitrobenzene sulfonic (TNBS) acid and obtaining colonic muscularis externae tissues 24 h later. TNBS inflammation induced intercellular adhesion molecule-1 (ICAM-1) expression by translocating NF-κB to the nucleus. The incubation of inflamed tissues with S-nitrosoglutathione (GSNO) did not affect the nuclear translocation of NF-κB; however, it suppressed the NF-κB binding to DNA. Chromatin immunoprecipitation analysis (ChIP)-qPCR assays showed that the increase in NF-κB/DNA interaction following inflammation is due to the transcriptional downregulation of global HDAC3 and a decrease in its interaction with the DNA on the Icam-1 promoter containing the binding motifs of NF-κB. The decrease in the association of histone deacetylase (HDAC) 3 with the Icam-1 promoter increased the acetylation of histone 4 lysine residue 12 (H4K12), which would favor chromatin relaxation and greater access of NF-κB to its DNA binding sites. HDAC3 dissociation from the DNA did not affect the acetylation levels of H4K8 and H4K16. The NO release by GSNO countered the upregulation of Icam-1 by increasing the transcription of global HDAC3 and its association with the Icam-1 promoter, and by suppressing H4K12 acetylation. We conclude that chromatin modification by transcriptional downregulation of HDAC3 plays a critical role in the induction of the inflammatory response. NO may serve as an anti-inflammatory mediator during the acute stage of inflammation by blunting the downregulation of global HDAC3, increasing HDAC3 interaction with the nucleosomes containing the binding moieties of NF-κB, reducing H4K12Ac to restrict the access of NF-κB to DNA, and suppressing ICAM-1 expression.

  8. Simultaneous determination of uric acid, xanthine, hypoxanthine and caffeine in human blood serum and urine samples using electrochemically reduced graphene oxide modified electrode.

    Science.gov (United States)

    Raj, M Amal; John, S Abraham

    2013-04-10

    This paper describes the fabrication of graphene on glassy carbon electrode (GCE) by electrochemical reduction of graphene oxide (GO) attached through 1,6-hexadiamine on GCE and the simultaneous determination of structurally similar four purine derivatives using the resultant electrochemically reduced GO (ERGO) modified electrode. The electrocatalytic activity of ERGO was investigated toward the oxidation of four important purine derivatives, uric acid (UA), xanthine (XN), hypoxanthine (HXN) and caffeine (CAF) at physiological pH. The modified electrode not only enhanced the oxidation currents of the four purine derivatives but also shifted their oxidation potentials toward less positive potentials in contrast to bare GCE. Further, it successfully separates the voltammetric signals of the four purine derivatives in a mixture and hence used for the simultaneous determination of them. Selective determination of one purine derivative in the presence of low concentrations other three purine derivatives was also realized at the present modified electrode. Using differential pulse voltammetry, detection limits of 8.8×10(-8)M, 1.1×10(-7)M, 3.2×10(-7)M and 4.3×10(-7)M were obtained for UA, XN, HXN and CAF, respectively. The practical application of the modified electrode was demonstrated by simultaneously determining the concentrations of UA, XN, HXN and CAF in human blood plasma and urine samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Green Preparation of Epoxy/Graphene Oxide Nanocomposites Using a Glycidylamine Epoxy Resin as the Surface Modifier and Phase Transfer Agent of Graphene Oxide.

    Science.gov (United States)

    Tang, Xinlei; Zhou, Yang; Peng, Mao

    2016-01-27

    In studies of epoxy/graphene oxide (GO) nanocomposites, organic solvents are commonly used to disperse GO, and vigorous mechanical processes and complicated modification of GO are usually required, increasing the cost and hindering the development and application of epoxy nanocomposites. Here, we report a green, facile, and efficient method of preparing epoxy/GO nanocomposites. When triglycidyl para-aminophenol (TGPAP), a commercially available glycidyl amine epoxy resin with one tertiary amine group per molecule, is used as both the surface modifier and phase transfer agent of GO, GO can be directly and rapidly transferred from water to diglycidyl ether of bisphenol A and other types of epoxy resins by manual stirring under ambient conditions, whereas GO cannot be transferred to these epoxy resins in the absence of TGPAP. The interaction between TGPAP and GO and the effect of the TGPAP content on the dispersion of GO in the epoxy matrix were investigated systematically. Superior dispersion and exfoliation of GO nanosheets and remarkably improved mechanical properties, including tensile and flexural properties, toughness, storage modulus, and microhardness, of the epoxy/GO nanocomposites with a suitable amount of TGPAP were demonstrated. This method is organic-solvent-free and technically feasible for large-scale preparation of high-performance nanocomposites; it opens up new opportunities for exploiting the unique properties of graphene or even other nanofillers for a wide range of applications.

  10. Cerium oxide nanoparticles alter the salt stress tolerance of Brassica napus L. by modifying the formation of root apoplastic barriers.

    Science.gov (United States)

    Rossi, Lorenzo; Zhang, Weilan; Ma, Xingmao

    2017-10-01

    Rapidly growing global population adds significant strains on the fresh water resources. Consequently, saline water is increasingly tapped for crop irrigation. Meanwhile, rapid advancement of nanotechnology is introducing more and more engineered nanoparticles into the environment and in agricultural soils. While some negative effects of ENPs on plant health at very high concentrations have been reported, more beneficial effects of ENPs at relatively low concentrations are increasingly noticed, opening doors for potential applications of nanotechnology in agriculture. In particular, we found that cerium oxide nanoparticles (CeO 2 NPs) improved plant photosynthesis in salt stressed plants. Due to the close connections between salt stress tolerance and the root anatomical structures, we postulated that CeO 2 NPs could modify plant root anatomy and improve plant salt stress tolerance. This study aimed at testing the hypothesis with Brassica napus in the presence of CeO 2 NPs (0, 500 mg kg -1 dry sand) and/or NaCl (0, 50 mM) in a growth chamber. Free hand sections of fresh roots were taken every seven days for three weeks and the suberin lamellae development was examined under a fluorescence microscope. The results confirmed the hypothesis that CeO 2 NPs modified the formation of the apoplastic barriers in Brassica roots. In salt stressed plants, CeO 2 NPs shortened the root apoplastic barriers which allowed more Na + transport to shoots and less accumulation of Na + in plant roots. The altered Na + fluxes and transport led to better physiological performance of Brassica and may lead to new applications of nanotechnology in agriculture. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Control of indium tin oxide anode work function modified using Langmuir-Blodgett monolayer for high-efficiency organic photovoltaics

    Directory of Open Access Journals (Sweden)

    Yuya Yokokura

    2017-08-01

    Full Text Available The use of Langmuir-Blodgett (LB monolayers to modify the indium tin oxide (ITO work function and thus improve the performance of zinc phthalocyanine (ZnPc/fullerene (C60-based and boron subphthalocyanine chloride (SubPc/C60-based small molecule organic photovoltaic devices (OPVs was examined. In general, LB precursor compounds contain one or more long alkyl chain substituents that can act as spacers to prevent electrical contact with adjoining electrode surfaces. As one example of such a compound, arachidic acid (CH3(CH218COOH was inserted in the forms of one-layer, three-layer or five-layer LB films between the anode ITO layer and the p-type layer in ZnPc-C60-based OPVs to investigate the effects of the long alkyl chain group when it acts as an electrically insulating spacer. The short-circuit current density (Jsc values of the OPVs with the three- and five-layer inserts (1.78 mA·cm−2 and 0.61 mA·cm−2, respectively were reduced dramatically, whereas the Jsc value for the OPV with the single-layer insertion (2.88 mA·cm−2 was comparable to that of the OPV without any insert (3.14 mA·cm-2. The ITO work function was shifted positively by LB deposition of a surfactant compound, C9F19C2H4-O-C2H4-COOH (PFECA, which contained a fluorinated head group. This positive effect was maintained even after formation of an upper p-type organic layer. The Jsc and open-circuit voltage (Voc of the SubPc-C60-based OPV with the LB-modified ITO layers were effectively enhanced. As a result, a 42% increase in device efficiency was achieved.

  12. Synthesis and characterization of the superparamagnetic iron oxide nanoparticles modified with cationic chitosan and coated with silica shell

    Energy Technology Data Exchange (ETDEWEB)

    Lewandowska-Łańcucka, Joanna, E-mail: lewandow@chemia.uj.edu.pl [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Staszewska, Magdalena; Szuwarzyński, Michał; Kępczyński, Mariusz [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland); Romek, Marek [Department of Cytology and Histology, Institute of Zoology, Jagiellonian University, Gronostajowa 9, 30-387 Krakow (Poland); Tokarz, Waldemar [Department of Solid State Physics, AGH University of Science and Technology, al. A. Mickiewicza 30, 30-059 Krakow (Poland); Szpak, Agnieszka; Kania, Gabriela; Nowakowska, Maria [Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Krakow (Poland)

    2014-02-15

    Highlights: • The new, facile methodology for synthesis of silica covered SPIONs is proposed. • The SPIONs was modified with cationic chitosan and coated with silica shell. • Negatively charged, rounded in shape particles of ca. 330 nm were obtained. • The product exhibits the superparamagnetic properties. • The product properties imply its potential applications in biomedicine areas. -- Abstract: Novel method for synthesis of superparamagnetic iron oxide nanoparticles (SPION) modified with a cationic chitosan (CCh) and coated with a silica shell, SPION-CCh-SiO{sub 2} was developed. The process was carried out in two steps. In the first step the chitosan coated SPIONs were obtained by co-precipitation of Fe{sup 2+} and Fe{sup 3+} with ammonium hydroxide in aqueous solution of CCh. In the second one, the silica shell is formed on their surfaces. The formation of SPION-CCh-SiO{sub 2} was achieved by direct decomposition of tetraethoxysilane (TEOS) adsorbed on a surface of SPION-CCh dispersed in aqueous phase under sonication and mechanical stirring at room temperature. The chemical composition and physicochemical properties of the materials were determined using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS) and zeta potential measurements. The morphology of the particles was evaluated by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). Magnetic properties were confirmed using Atomic Force Microscopy/Magnetic Force Microscopy (AFM/MFM) and magnetization measurements. The resulting products are negatively charged, rounded in shape and exhibit the superparamagnetic properties what implies their potential applications in engineering and biomedicine areas.

  13. Synthesis and characterization of the superparamagnetic iron oxide nanoparticles modified with cationic chitosan and coated with silica shell

    International Nuclear Information System (INIS)

    Lewandowska-Łańcucka, Joanna; Staszewska, Magdalena; Szuwarzyński, Michał; Kępczyński, Mariusz; Romek, Marek; Tokarz, Waldemar; Szpak, Agnieszka; Kania, Gabriela; Nowakowska, Maria

    2014-01-01

    Highlights: • The new, facile methodology for synthesis of silica covered SPIONs is proposed. • The SPIONs was modified with cationic chitosan and coated with silica shell. • Negatively charged, rounded in shape particles of ca. 330 nm were obtained. • The product exhibits the superparamagnetic properties. • The product properties imply its potential applications in biomedicine areas. -- Abstract: Novel method for synthesis of superparamagnetic iron oxide nanoparticles (SPION) modified with a cationic chitosan (CCh) and coated with a silica shell, SPION-CCh-SiO 2 was developed. The process was carried out in two steps. In the first step the chitosan coated SPIONs were obtained by co-precipitation of Fe 2+ and Fe 3+ with ammonium hydroxide in aqueous solution of CCh. In the second one, the silica shell is formed on their surfaces. The formation of SPION-CCh-SiO 2 was achieved by direct decomposition of tetraethoxysilane (TEOS) adsorbed on a surface of SPION-CCh dispersed in aqueous phase under sonication and mechanical stirring at room temperature. The chemical composition and physicochemical properties of the materials were determined using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS) and zeta potential measurements. The morphology of the particles was evaluated by Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). Magnetic properties were confirmed using Atomic Force Microscopy/Magnetic Force Microscopy (AFM/MFM) and magnetization measurements. The resulting products are negatively charged, rounded in shape and exhibit the superparamagnetic properties what implies their potential applications in engineering and biomedicine areas

  14. Control of indium tin oxide anode work function modified using Langmuir-Blodgett monolayer for high-efficiency organic photovoltaics

    Science.gov (United States)

    Yokokura, Yuya; Dogase, Tomomichi; Shinbo, Tatsuki; Nakayashiki, Yuya; Takagi, Yusuke; Ueda, Kazuyoshi; Sarangerel, Khayankhyarvaa; Delgertsetseg, Byambasuren; Ganzorig, Chimed; Sakomura, Masaru

    2017-08-01

    The use of Langmuir-Blodgett (LB) monolayers to modify the indium tin oxide (ITO) work function and thus improve the performance of zinc phthalocyanine (ZnPc)/fullerene (C60)-based and boron subphthalocyanine chloride (SubPc)/C60-based small molecule organic photovoltaic devices (OPVs) was examined. In general, LB precursor compounds contain one or more long alkyl chain substituents that can act as spacers to prevent electrical contact with adjoining electrode surfaces. As one example of such a compound, arachidic acid (CH3(CH2)18COOH) was inserted in the forms of one-layer, three-layer or five-layer LB films between the anode ITO layer and the p-type layer in ZnPc-C60-based OPVs to investigate the effects of the long alkyl chain group when it acts as an electrically insulating spacer. The short-circuit current density (Jsc) values of the OPVs with the three- and five-layer inserts (1.78 mA.cm-2 and 0.61 mA.cm-2, respectively) were reduced dramatically, whereas the Jsc value for the OPV with the single-layer insertion (2.88 mA.cm-2) was comparable to that of the OPV without any insert (3.14 mA.cm-2). The ITO work function was shifted positively by LB deposition of a surfactant compound, C9F19C2H4-O-C2H4-COOH (PFECA), which contained a fluorinated head group. This positive effect was maintained even after formation of an upper p-type organic layer. The Jsc and open-circuit voltage (Voc) of the SubPc-C60-based OPV with the LB-modified ITO layers were effectively enhanced. As a result, a 42% increase in device efficiency was achieved.

  15. Synthesis of palladium nanoparticle modified reduced graphene oxide and multi-walled carbon nanotube hybrid structures for electrochemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jie, E-mail: hujie@tyut.edu.cn [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); Zhao, Zhenting; Zhang, Jun; Li, Gang; Li, Pengwei; Zhang, Wendong [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); Lian, Kun, E-mail: liankun@tyut.edu.cn [Micro and Nano System Research Center, Key Lab of Advanced Transducers and Intelligent Control System (Ministry of Education) & College of Information Engineering, Taiyuan University of Technology, Taiyuan, 030024, Shanxi (China); School of Nano-Science and Nano-Engineering, Suzhou & Collaborative Innovation Center of Suzhou Nano Science and Technology, Xi' an Jiaotong University, Xi' an, 710049 (China); Center for Advanced Microstructures and Devices, Louisiana State University, LA, 70806 (United States)

    2017-02-28

    Graphical abstract: A sensitive hydrazine electrochemical sensor was fabricated by using palladium (Pd) nanoparticle functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotube (MWCNTs) hybrid structures (Pd/rGO-MWCNTs). - Highlights: • rGO-MWCNTs hybrid structures and Pd nanoparticles are prepared using electrochemical methods. • rGO-MWCNTs hybrid films are used as supports and co-catalysts for Pd nanoparticles. • The Pd/rGO-MWCNTs hybrid structure based sensor shows an ultra-high sensitivity of 7.09 μA μM{sup −1} cm{sup −2} and a low detection limit of 0.15 μM. • The proposed electrochemical sensor exhibits excellent selectivity. - Abstract: In this work, palladium (Pd) nanoparticles functionalized reduced graphene oxide (rGO) and multi-walled carbon nanotubes (MWCNTs) hybrid structures (Pd/rGO-MWCNTs) were successfully prepared by a combination of electrochemical reduction with electrodeposition method. The morphology, structure, and composition of the Pd/rGO-MWCNTs hybrid were characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive spectroscopy. The as-synthesized hybrid structures were modified on the glassy carbon electrode (GCE) and further utilized for hydrazine sensing. Electrochemical impedance spectroscopic, cyclic voltammetry and single-potential amperometry experiments were carried out on Pd/rGO-MWCNTs hybrid structures to investigate the interface properties and sensing performance. The measured results demonstrate that the fabricated Pd/rGO-MWCNTs/GCE sensor show a high sensitivity of 7.09 μA μM{sup −1} cm{sup −2} in a large concentration range of 1.0 to 1100 μM and a low detection limit of 0.15 μM. Moreover, the as-prepared sensor exhibits good selectivity and stability for the determination of hydrazine under interference conditions.

  16. Surface characterization and corrosion behavior of micro-arc oxidized Ti surface modified with hydrothermal treatment and chitosan coating

    International Nuclear Information System (INIS)

    Neupane, Madhav Prasad; Park, Il Song; Lee, Min Ho

    2014-01-01

    In the present work, we describe the surface modification of commercially pure titanium (CP-Ti) by a composite/multilayer coating approach for biomedical applications. CP-Ti samples were treated by micro-arc oxidation (MAO) and subsequently some of the samples were coated with chitosan (Chi) by dip coating method, while others were subjected to hydrothermal treatment (HT) followed by chitosan coating. The MAO, MAO/Chi, and MAO/HT/Chi coated Ti were characterized and their characteristics were compared with CP-Ti. X-ray diffraction and scanning electron microscopy were used to assess the structural and morphological characteristics. The average surface roughness was determined using a surface profilometer. The corrosion resistance of untreated and surface modified Ti in commercial saline at 298 K was evaluated by potentiodynamic polarization test. The results indicated that the chitosan coating is very well integrated with the MAO and MAO/HT coating by physically interlocking itself with the coated layer and almost sealed all the pores. The surface roughness of hydrothermally treated and chitosan coated MAO film was superior evidently to that with other sample groups. The corrosion studies demonstrated that the MAO, hydrothermally treated and chitosan coated sample enhanced the corrosion resistance of titanium. The result indicates that fabrication of hydrothermally treated MAO surface coatings with chitosan is a significant approach to protect the titanium from corrosion, hence enhancing the potential use of titanium as bio-implants. - Highlights: • Micro-arc oxidized (MAO) and hydrothermally treated (HT) Ti surfaces are coated with chitosan (Chi). • The MAO/HT/Chi surface exhibits pores sealing and enhanced the surface roughness. • The MAO/HT/Chi surface significantly increase the corrosion resistance. • The MAO/HT/Chi can be a potential surface of titanium for bio-implants

  17. A directional entrapment modification on the polyethylene surface by the amphiphilic modifier of stearyl-alcohol poly(ethylene oxide) ether

    Science.gov (United States)

    Lu, Qiang; Chen, Yi; Huang, Juexin; Huang, Jian; Wang, Xiaolin; Yao, Jiaying

    2018-05-01

    A novel entrapment modification method involving directional implantation of the amphiphilic modifier of stearyl-alcohol poly(ethylene oxide) ether (AEO) into the high-density polyethylene (HDPE) surface is proposed. This modification technique allows the AEO modifier to be able to spontaneously attain and subsequently penetrate into the swollen HDPE surface with its hydrophobic stearyl segment, while its hydrophilic poly(ethylene oxide) (PEO) segment spontaneously points to water. The AEO modifier with a HLB number below 8.7 was proved appropriate for the directional entrapment, Nevertheless, AEOs with larger HLB numbers were also effective modifiers in the presence of salt additives. In addition, a larger and hydrophobic micelle, induced respectively by the AEO concentration above 1.3 × 10-2 mol/L and the entrapping temperature above the cloud point of AEO, could lead to a sharp contact angle decline of the modified surface. Finally, a hydrophilic HDPE surface with the modifier coverage of 38.9% was reached by the directional entrapment method, which is far larger than that of 19.2% by the traditional entrapment method.

  18. Magnetic iron oxide modified pyropheophorbide-a fluorescence nanoparticles as photosensitizers for photodynamic therapy against ovarian cancer (SKOV-3) cells.

    Science.gov (United States)

    Tan, Guanghui; Li, Wenting; Cheng, Jianjun; Wang, Zhiqiang; Wei, Shuquan; Jin, Yingxue; Guo, Changhong; Qu, Fengyu

    2016-11-30

    Magnetic iron oxide modified pyropheophorbide-a fluorescence nanoparticles, Fe 3 O 4 @SiO 2 @APTES@PPa (FSAP), were designed as magnetically targeted photodynamic antineoplastic agents and prepared through continuous covalent chemical modification on the surface of Fe 3 O 4 nanoparticles. The properties of the intermediates and the final product were comprehensively characterized by transmission electron microscopy, powder X-ray diffraction analysis, Fourier transform infrared spectroscopy, vibrating sample magnetometry, zeta potential measurement, ultraviolet-visible absorption spectroscopy, fluorescence emission spectroscopy, and thermogravimetric analysis. In this work, we demonstrated the in vitro photodynamic therapy (PDT) of FSAP against ovarian cancer (SKOV-3) cells, which indicated that FSAP could be taken up successfully and showed low dark toxicity without irradiation, but remarkable phototoxicity after irradiation. Meanwhile, FSAP had showed good biocompatibility and low dark toxicity against normal cells in the biological experiments on mouse normal fibroblast cell lines (L929 cells). In addition, in the photochemical process of FSAP mediated photodynamic therapy, the Type-II photo-oxygenation process (generated singlet oxygen) played an important role in the induction of cell damage.

  19. Reduced graphene oxide modified NiFe-calcinated layered double hydroxides for enhanced photocatalytic removal of methylene blue

    Science.gov (United States)

    Zhao, Guoqing; Li, Caifeng; Wu, Xia; Yu, Jingang; Jiang, Xinyu; Hu, Wenjihao; Jiao, Feipeng

    2018-03-01

    Calcined layered double hydroxides (CLDH) are one of the remarkable photocatalysts passionately studied for photodecolorization of organic dyes. NiFe-CLDH was successfully modified by reduced graphene oxide (RGO) through a facile in situ crystallization technique. The obtained RGO/NiFe-CLDH composites were fully characterized by powder X-ray diffraction (XRD), Scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FT-IR), and UV-vis diffuse reflectance spectroscopy (DRS). The results analysis indicated that RGO sheets could work as base course to prompt the growth of LDH crystallites and NiFe-LDH lamellar crystal promiscuously distributed on the sheets with a strong interplay between each other. The photocatalytic performance of RGO/NiFe-CLDH composites toward decolorization of methylene blue tightly depended on the mass fraction of RGO and calcinated temperature. At the RGO weight loading of 1%, calcination temperature of 500 °C, the photocatalytic degradation efficiency of RGO/NiFe-CLDH composites reached 93.0% within 5.0 h. The enhanced activity of RGO/NiFe-CLDH composites may be due to the concerted catalysis effect between two constituents of as-prepared composites.

  20. Pilot-scale demonstration of the modified direct denitration process to prepare uranium oxide for fuel fabrication evaluation

    International Nuclear Information System (INIS)

    Kitts, F.G.

    1994-04-01

    The Uranium-Atomic Vapor Laser Isotope Separation (U-AVLIS) Program has the objective of developing a cost-competitive enrichment process that will ultimately replace the gaseous diffusion process used in the United States. Current nuclear fuel fabricators are set up to process only the UF 6 product from gaseous diffusion enrichment. Enriched uranium-iron alloy from the U-AVLIS separator system must be chemically converted into an oxide form acceptable to these fabricators to make fuel pellets that meet American Society for Testing and Materials (ASTM) and utility company specifications. A critical step in this conversion is the modified direct denitration (MDD) that has been selected and presented in the AVLIS Conceptual Design for converting purified uranyl nitrate to UO 3 to be shipped to fabricators for making UO 2 pellets for power reactor fuel. This report describes the MDD process, the equipment used, and the experimental work done to demonstrate the conversion of AVLIS product to ceramic-grade UO 3 suitable for making reactor-grade fuel pellets

  1. Hyaluronic Acid-Modified Magnetic Iron Oxide Nanoparticles for MR Imaging of Surgically Induced Endometriosis Model in Rats

    Science.gov (United States)

    Sun, Wenjie; Hu, Yong; Zhang, Guofu; Shen, Mingwu; Shi, Xiangyang

    2014-01-01

    Endometriosis is defined as the presence of endometrial tissue outside the uterine, which may affect nearly 60% of women in reproductive age. Deep infiltrating endometriosis (DIE) defined as an endometriotic lesion penetrating into the retroperitoneal space or the wall of the pelvic organs to a depth of at least 5 mm represents the most diagnostic challenge. Herein, we reported the use of hyaluronic acid (HA)-modified magnetic iron oxide nanoparticles (HA-Fe3O4 NPs) for magnetic resonance (MR) imaging of endometriotic lesions in the rodent model. Sixteen endometriotic lesions were surgically induced in eight rats by autologous transplantation. Four weeks after lesion induction, three rats were scanned via MR imaging after tail vein injection of the HA-Fe3O4 NPs. Accordingly, the remaining five mice were sacrificed in the corresponding time points. The ectopic uterine tissues (EUTs) were confirmed by histological analysis. Quantification of Fe in the EUT was also performed by inductively coupled plasma-optical emission spectroscopy. Our results showed that by using the HA-Fe3O4 NPs, the EUTs were able to be visualized via T2-weighted MR imaging at 2 hours post injection, corroborating the Prussian blue staining results. The developed HA-Fe3O4 NPs could be used as negative contrast agents for sensitively detecting endometriosis in a mouse model and may be applied for future hyperthermia treatment of endometriosis. PMID:24722347

  2. Hyaluronic acid-modified magnetic iron oxide nanoparticles for MR imaging of surgically induced endometriosis model in rats.

    Directory of Open Access Journals (Sweden)

    He Zhang

    Full Text Available Endometriosis is defined as the presence of endometrial tissue outside the uterine, which may affect nearly 60% of women in reproductive age. Deep infiltrating endometriosis (DIE defined as an endometriotic lesion penetrating into the retroperitoneal space or the wall of the pelvic organs to a depth of at least 5 mm represents the most diagnostic challenge. Herein, we reported the use of hyaluronic acid (HA-modified magnetic iron oxide nanoparticles (HA-Fe3O4 NPs for magnetic resonance (MR imaging of endometriotic lesions in the rodent model. Sixteen endometriotic lesions were surgically induced in eight rats by autologous transplantation. Four weeks after lesion induction, three rats were scanned via MR imaging after tail vein injection of the HA-Fe3O4 NPs. Accordingly, the remaining five mice were sacrificed in the corresponding time points. The ectopic uterine tissues (EUTs were confirmed by histological analysis. Quantification of Fe in the EUT was also performed by inductively coupled plasma-optical emission spectroscopy. Our results showed that by using the HA-Fe3O4 NPs, the EUTs were able to be visualized via T2-weighted MR imaging at 2 hours post injection, corroborating the Prussian blue staining results. The developed HA-Fe3O4 NPs could be used as negative contrast agents for sensitively detecting endometriosis in a mouse model and may be applied for future hyperthermia treatment of endometriosis.

  3. Iron porphyrin-modified PVDF membrane as a biomimetic material and its effectiveness on nitric oxide binding

    Science.gov (United States)

    Can, Faruk; Demirci, Osman Cahit; Dumoulin, Fabienne; Erhan, Elif; Arslan, Leyla Colakerol; Ergenekon, Pınar

    2017-10-01

    Nitric oxide (NO) is a reactive gas well-known as an air pollutant causing severe environmental problems. NO is also an important signaling molecule having a strong affinity towards heme proteins in the body. Taking this specialty as a model, a biomimetic membrane was developed by modification of the membrane surface with iron-porphyrin which depicts very similar structure to heme proteins. In this study, PVDF membrane was coated with synthesized (4-carboxyphenyl)-10,15,20-triphenyl-porphyrin iron(III) chloride (FeCTPP) to promote NO fixation on the surface. The coated membrane was characterized in terms of ATR-IR spectra, contact angle measurement, chemical composition, and morphological structure. Contact angle of original PVDF first decreased sharply after plasma treatment and surface polymerization steps but after incorporation of FeCTPP, the surface acquired its hydrophobicity again. NO binding capability of modified membrane surface was evaluated on the basis of X-ray Photoelectron. Upon exposure to NO gas, a chemical shift of Fe+3 and appearance of new N peak was observed due to the electron transfer from NO ligand to Fe ion with the attachment of nitrosyl group to FeCTPP. This modification brings the functionality to the membrane for being used in biological systems such as membrane bioreactor material in biological NO removal technology.

  4. Constructing proton-conductive highways within an ionomer membrane by embedding sulfonated polymer brush modified graphene oxide

    Science.gov (United States)

    Zhao, Liping; Li, Yifan; Zhang, Haoqin; Wu, Wenjia; Liu, Jindun; Wang, Jingtao

    2015-07-01

    Sulfonated polymer brush modified graphene oxide (SP-GO) fillers with controllable brush length are synthesized via the facile distillation-precipitation polymerization, and then incorporated into sulfonated poly(ether ether ketone) (SPEEK) matrix to fabricate composite membranes. The influences of SP-GO upon the microstructures, including thermal and mechanical properties, water uptake/swelling, proton conduction, H2 permeability and single PEMFC performances of composite membranes are intensively investigated. It is found that the SP-GO fillers are uniformly dispersed and tend to lie perpendicularly to the cross-section surface of the whole membrane, which allow SP-GO fillers creating inter-connected and broad ionic pathways through the sulfonic acid groups in polymer brushes. Meanwhile, the SP-GO fillers connect the ionic clusters in SPEEK matrix via interfacial interactions. In such a way, proton-transfer highways are constructed along the SPEEK/SP-GO interface, which lower the proton transfer activation energy and enhance the proton conductivities of the composite membranes under both hydrated and anhydrous conditions. Furthermore, elevating the brush length on SP-GO could further enhance the proton conductivity. Compared to SPEEK control membrane, a 95.5% increase in hydrated conductivity, an 178% increase in anhydrous conductivity and a 37% increase in maximum power density are obtained for the optimal composite membrane.

  5. Natural silica sand modified by calcium oxide as a new adsorbent for uranyl ions removal from aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Elhefnawy, O.A.; Elabd, A.A. [Nuclear and Radiological Regulatory Authority (NRRA), Cairo (Egypt). Nuclear Safeguards and Physical Protection Dept.

    2017-07-01

    Calcium oxide modified El-Zafarana silica sand (CMZS) was prepared as a new adsorbent for U(VI) removal from aqueous solutions in a series of batch experiments. The new adsorbent CMZS was characterized by different analysis techniques SEM, EDX, XRD, and FTIR. The influence of many parameters on the removal process like; effect of pH, contact time, U(VI) initial concentration and temperature on U(VI) removal were investigated. Kinetic experiments showed that U(VI) removal on CMZS followed pseudo-second-order kinetics model appropriately and the equilibrium data agreed well with the Langmuir isotherm model. Kinetics and isothermal data reveal the chemisorption process of U(VI) on CMZS. The thermodynamic parameters (ΔH {sup circle}, ΔS {sup circle}, ΔG {sup circle}) were evaluated from temperature dependent adsorption data and the U(VI) removal on CMZS was found to be endothermic and spontaneous in nature. U(VI) desorption from CMZS was studied by a simple acid treatment. The results indicate that CMZS is an effective adsorbent for U(VI) from aqueous solutions.

  6. A disposable chronocoulometric sensor for heavy metal ions using a diaminoterthiophene-modified electrode doped with graphene oxide

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Seung-Min; Kim, Dong-Min; Jung, Ok-Sang; Shim, Yoon-Bo, E-mail: ybshim@pusan.ac.kr

    2015-09-10

    The rapid simultaneous determination of cadmium, lead, copper, and mercury ions is performed by employing a disposable sensor modified with graphene oxide (GO) doped diaminoterthiophene (GO/DTT) for chronocoulometry (CC). The performances of CC with and without pre-deposition in two opposite potential step directions were compared with square wave anodic stripping voltammetry (SWASV) under various conditions. The surface of the GO/DTT modified screen print carbon electrode (SPCE) was characterized by SEM, EDXS, and electrochemical impedance spectroscopy (EIS). Experimental variables that affect the response signal such as the pH, deposition time, type of supporting electrolyte, concentration of DTT, content ratio of GO to DTT, and Nafion content were optimized. Interference effects due to other heavy metal ions were also investigated. The dynamic ranges of SWASV and CC were between 1 ng mL{sup −1} and 2.5 μg mL{sup −1} and between 1 ng mL{sup −1} and 10 μg mL{sup −1}, respectively. The detection limits for Cd{sup 2+}, Pb{sup 2+}, Cu{sup 2+}, Hg{sup 2+} ions were 1.9 ± 0.4 ng mL{sup −1}, 2.8 ± 0.6 ng mL{sup −1}, 0.8 ± 0.2 ng mL{sup −1}, and 2.6 ± 0.9 ng mL{sup −1} for the CC stripping method; 2.6 ± 0.2 ng mL{sup −1}, 0.5 ± 0.1 ng mL{sup −1}, 1.8 ± 0.3 ng mL{sup −1}, and 3.2 ± 0.3 ng mL{sup −1} for the CC deposition method; and 7.1 ± 0.9, 1.9 ± 0.3, 0.4 ± 0.1, and 0.7 ± 0.1 ng mL{sup −1} for SWASV. The reliability of the method for point-of-analysis was evaluated by analyzing a urine standard reference material and some water samples. - Highlights: • The electrode modified with graphene oxide doped organic ligand. • Rapid detection of Cd{sup 2+}, Pb{sup 2+}, Cu{sup 2+}, and Hg{sup 2+} ions by using chronocoulometry. • The result of proposed method was compared with the conventional method.

  7. Evaluation of structure, chaperone-like activity and protective ability of peroxynitrite modified human α-Crystallin subunits against copper-mediated ascorbic acid oxidation.

    Science.gov (United States)

    Ghahramani, Maryam; Yousefi, Reza; Khoshaman, Kazem; Moghadam, Sogand Sasan; Kurganov, Boris I

    2016-06-01

    The copper-catalyzed oxidation of ascorbic acid (ASA) to dehydroascorbate (DHA) and hydrogen peroxide plays a central role in pathology of cataract diseases during ageing and in diabetic patients. In the current study, the structural feature, chaperone-like activity and protective ability of peroxynitrite (PON) modified αA- and αB-Crystallin (Cry) against copper-mediated ASA oxidation were studied using different spectroscopic measurements and gel mobility shift assay. Upon PON modification, additional to protein structural alteration, the contents of nitrotyrosine, nitrotryptophan, dityrosine and carbonyl groups were significantly increased. Moreover, αB-Cry demonstrates significantly larger capacity for PON modification than αA-Cry. Also, based on the extent of PON modification, these proteins may display an improved chaperone-like activity and enhanced protective ability against copper-mediated ASA oxidation. In the presence of copper ions, chaperone-like activity of both native and PON-modified α-Cry subunits were appreciably improved. Additionally, binding of copper ions to native and PON-modified proteins results in the significant reduction of their solvent exposed hydrophobic patches. Overall, the increase in chaperone-like activity/ASA protective ability of PON-modified α-Cry and additional enhancement of its chaperoning action with copper ions appear to be an important defense mechanism offered by this protein. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. In-situ synthesis of reduced graphene oxide modified lithium vanadium phosphate for high-rate lithium-ion batteries via microwave irradiation

    International Nuclear Information System (INIS)

    Wang, Zhaozhi; Guo, Haifu; Yan, Peng

    2015-01-01

    Highlights: • Graphene-decorated Li 3 V 2 (PO 4 ) 3 is synthesized via microwave irradiation. • Both Li 3 V 2 (PO 4 ) 3 and RGO can be simultaneously achieved through this route. • The GO is reduced by microwave irradiation not the carbon. • Li 3 V 2 (PO 4 ) 3 /RGO displays excellent high-rate ability and cyclic stability. - Abstract: We report a simple and rapid method to synthesize graphene-modified Li 3 V 2 (PO 4 ) 3 as cathode material for lithium-ion batteries via microwave irradiation. By treating graphene oxide and the precursor of Li 3 V 2 (PO 4 ) 3 in a commercial microwave oven, both reduced graphene oxide and Li 3 V 2 (PO 4 ) 3 could be simultaneously synthesized within 5 min. The structure, morphology and electrochemical performances of as-synthesized graphene-modified Li 3 V 2 (PO 4 ) 3 are investigated systematically by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, charge/discharge tests, electrochemical impedance spectra (EIS) and cyclic voltammetry (CV). The XRD result indicates that single-phase graphene-modified Li 3 V 2 (PO 4 ) 3 with monoclinic structure can be obtained. Both SEM and TEM images show that Li 3 V 2 (PO 4 ) 3 nanocrystals are embedded in the reduced graphene oxide sheets which could provide an easy path for the electrons and Li-ions during the cycling process. Compared with the pristine Li 3 V 2 (PO 4 ) 3 electrode, graphene-modified Li 3 V 2 (PO 4 ) 3 exhibits a better high-rate ability and cyclic stability. These superior electrochemical performances are attributed to the good conductivity of reduced graphene oxide which enhances the electrons and Li-ions transport on the surface of Li 3 V 2 (PO 4 ) 3 . Thus, this simple and rapid method could be promising to synthesize graphene-modified electrode materials

  9. Effect of temperature on the rheological properties with shear stress limit of iron oxide nanoparticle modified bentonite drilling muds

    Directory of Open Access Journals (Sweden)

    Ahmed S. Mohammed

    2017-09-01

    Full Text Available In this study, the effect of temperature on the rheological properties and weight loss of a water based bentonite drilling mud modified with iron oxide nanoparticle (nanoFe2O3 was investigated. The bentonite contents in the drilling muds were varied up to 6% by the weight of water and temperature was varied from 25 °C to 85 °C. The nanoFe2O3 content was varied between 0 and 1% by the weight of the drilling mud to modify the rheological properties of the drilling mud. The nanoFe2O3 and bentonite clay were characterized using the X-ray diffraction analysis (XRD and thermal gravimetric analysis (TGA. In the TGA study, the total weight loss at 800 °C for the bentonite decreased from 13% to 1.16%, a 91% reduction when the bentonite clay was mixed with 1% of nanoFe2O3. The results also showed that 1% of nanoFe2O3 increased the rheological properties of the drilling mud. The nanoFe2O3 modification increased the yield stress (τo and plastic viscosity (PV by 45–200% and 20–105% respectively based on the bentonite content and temperature of the drilling mud. The shear thinning behavior of the bentonite drilling mud with and without nanoFe2O3 has been quantified using the hyperbolic model and compared with three parameters Herschel–Bulkley model. The results showed that the hyperbolic model predicted the shear thinning relationship between the shear stress and shear strain rate of the nanoFe2O3 modified bentonite drilling mud very well. Also the hyperbolic model has a maximum shear stress limit whereas the Herschel–Bulkley model did not have a limit on the maximum shear stress. Based on the hyperbolic model the maximum shear stress for the 2%, 4% and 6% bentonite drilling muds without nanoFe2O3 at room temperature were 25 Pa, 35 Pa and 51 Pa respectively. The maximum shear stress for the 2%, 4% and 6% bentonite drilling muds modified with 1% nanoFe2O3 at 25 °C were 59 Pa, 84 Pa and 140 Pa respectively, hence an increase of 135–175

  10. Effects of copper sulfate-oxidized or myeloperoxidase- modified LDL on lipid loading and programmed cell death in macrophages under hypoxia

    Directory of Open Access Journals (Sweden)

    Vlaminck B

    2014-09-01

    Full Text Available Benoit Vlaminck,1 Damien Calay,1 Marie Genin,1 Aude Sauvage,1 Noelle Ninane,1 Karim Zouaoui Boudjeltia,2 Martine Raes,1 Carine Michiels1 1Laboratory of Biochemistry and Cellular Biology (URBC, Namur Research Institute for Life Sciences (NARILIS, University of Namur, Namur, Belgium; 2Laboratory of Experimental Medicine (ULB 222 Unit, Universite Libre de Bruxelles, CHU de Charleroi, Charleroi, Belgium Abstract: Atheromatous plaques contain heavily lipid-loaded macrophages that die, hence generating the necrotic core of these plaques. Since plaque instability and rupture is often correlated with a large necrotic core, it is important to understand the mechanisms underlying foam cell death. Furthermore, macrophages within the plaque are associated with hypoxic areas but little is known about the effect of low oxygen partial pressure on macrophage death. The aim of this work was to unravel macrophage death mechanisms induced by oxidized low-density lipoproteins (LDL both under normoxia and hypoxia. Differentiated macrophages were incubated in the presence of native, copper sulfate-oxidized, or myeloperoxidase-modified LDL. The unfolded protein response, apoptosis, and autophagy were then investigated. The unfolded protein response and autophagy were triggered by myeloperoxidase-modified LDL and, to a larger extent, by copper sulfate-oxidized LDL. Electron microscopy observations showed that oxidized LDL induced excessive autophagy and apoptosis under normoxia, which were less marked under hypoxia. Myeloperoxidase-modified LDL were more toxic and induced a higher level of apoptosis. Hypoxia markedly decreased apoptosis and cell death, as marked by caspase activation. In conclusion, the cell death pathways induced by copper sulfate-oxidized and myeloperoxidase-modified LDL are different and are differentially modulated by hypoxia. Keywords: Ox-LDL, myeloperoxidase, hypoxia, UPR, apoptosis, autophagy, macrophages

  11. Application of walnut shell modified with Zinc Oxide (ZnO nanoparticles in removal of natural organic matters (NOMs from aqueous solution

    Directory of Open Access Journals (Sweden)

    ali naghizadeh

    2015-10-01

    Full Text Available Background & Aims of the Study: Natural organic matters (NOMs are a mixture of chemically complex polyelectrolytes produced mainly from the decomposition of plant and animal residues that are present in all surface and groundwater resources. This paper evaluates the aqueous NOMs adsorption efficiency on walnut shell modified with Zinc Oxide (ZnO. Materials & Methods: This study examined the feasibility of removing NOMs from aqueous solutions using walnut shell modified with ZnO. The effects of NOMs concentration, modified walnut shell with ZnO dosage, and pH on adsorption of NOMs by modified walnut shell with ZnO were evaluated. Results: The adsorption capacities of modified walnut shell with ZnO in the best conditions were 37.93 mg/g. The results also demonstrated that adsorption capacity of NOMs on modified walnut shell with ZnO was higher in lower pHs due to significantly high electrostatic attraction exists between the positively charged surface of the adsorbent and negatively charged NOMs. And finally adsorption capacity decreases as adsorbent dose increase. Conclusion: Walnut shell modified with ZnO can be proposed as a natural adsorbent in the removal of NOMs from aqueous solutions

  12. Epoxy composites coating with Fe3O4 decorated graphene oxide: Modified bio-inspired surface chemistry, synergistic effect and improved anti-corrosion performance

    Science.gov (United States)

    Zhan, Yingqing; Zhang, Jieming; Wan, Xinyi; Long, Zhihang; He, Shuangjiang; He, Yi

    2018-04-01

    To obtain graphene or graphene derivatives based epoxy composite coatings with high anti-corrosion performance, the morphology of nanostructures, dispersion, and interfacial adhesion are key factors that need to be considered. We here demonstrated the bio-inspired co-modification of graphene oxide/Fe3O4 hybrid (GO-Fe3O4@ poly (DA+KH550)) and its synergistic effect on the anti-corrosion performance of epoxy coating. For this purpose, graphene oxide/Fe3O4 hybrid obtained from hydrothermal route was modified by self-polymerization between dopamine and secondary functional monomer (KH550), which led to the modified bio-inspired surface functionalization. This novel modified bio-inspired functionalization was quite distinct from conventional surface modification or decoration. Namely, abundant amino groups were introduced by modified bio-inspired functionalization, which allowed the graphene oxide/Fe3O4 hybrid to disperse well in epoxy resin and enhanced the interfacial adhesion between modified nanofiller and epoxy resin through chemical crosslinking reaction. The electrochemical impedance spectroscopy (EIS) test revealed that anti-corrosive performance of epoxy coatings was significantly enhanced by addition of 0.5 wt% modified bio-inspired functionalized GO-Fe3O4 hybrid compared with neat epoxy and other nanofillers/epoxy composite coatings. Moreover, the micro-hardness of epoxy coating was enhanced by 71.8% compared with pure epoxy coating at the same loading content. In addition, the anticorrosion mechanism of GO-Fe3O4@poly (DA+KH550) was tentatively discussed.

  13. A disposable chronocoulometric sensor for heavy metal ions using a diaminoterthiophene-modified electrode doped with graphene oxide.

    Science.gov (United States)

    Choi, Seung-Min; Kim, Dong-Min; Jung, Ok-Sang; Shim, Yoon-Bo

    2015-09-10

    The rapid simultaneous determination of cadmium, lead, copper, and mercury ions is performed by employing a disposable sensor modified with graphene oxide (GO) doped diaminoterthiophene (GO/DTT) for chronocoulometry (CC). The performances of CC with and without pre-deposition in two opposite potential step directions were compared with square wave anodic stripping voltammetry (SWASV) under various conditions. The surface of the GO/DTT modified screen print carbon electrode (SPCE) was characterized by SEM, EDXS, and electrochemical impedance spectroscopy (EIS). Experimental variables that affect the response signal such as the pH, deposition time, type of supporting electrolyte, concentration of DTT, content ratio of GO to DTT, and Nafion content were optimized. Interference effects due to other heavy metal ions were also investigated. The dynamic ranges of SWASV and CC were between 1 ng mL(-1) and 2.5 μg mL(-1) and between 1 ng mL(-1) and 10 μg mL(-1), respectively. The detection limits for Cd(2+), Pb(2+), Cu(2+), Hg(2+) ions were 1.9 ± 0.4 ng mL(-1), 2.8 ± 0.6 ng mL(-1), 0.8 ± 0.2 ng mL(-1), and 2.6 ± 0.9 ng mL(-1) for the CC stripping method; 2.6 ± 0.2 ng mL(-1), 0.5 ± 0.1 ng mL(-1), 1.8 ± 0.3 ng mL(-1), and 3.2 ± 0.3 ng mL(-1) for the CC deposition method; and 7.1 ± 0.9, 1.9 ± 0.3, 0.4 ± 0.1, and 0.7 ± 0.1 ng mL(-1) for SWASV. The reliability of the method for point-of-analysis was evaluated by analyzing a urine standard reference material and some water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Electrocatalytic oxidation of diethylaminoethanethiol and hydrazine at single-walled carbon nanotubes modified with prussian blue nanoparticles

    CSIR Research Space (South Africa)

    Adekunle, AS

    2010-11-01

    Full Text Available In this work, edged plane pyrolytic graphite electrode EPPGE was modified with functionalised single-walled carbon nanotubes and Prussian blue nanoparticles (PB). The modified electrode was characterised by techniques such as TEM, FTIR, XPS, EDX...

  15. Synthesis of a novel thermo/pH sensitive nanogel based on salep modified graphene oxide for drug release

    International Nuclear Information System (INIS)

    Bardajee, Ghasem Rezanejade; Hooshyar, Zari; Farsi, Maryam; Mobini, Akram; Sang, Golnaz

    2017-01-01

    Nanogels (NGs) are three-dimensional water soluble cross-linked hydrogel materials in the nanoscale size range with a high loading capacity for guest molecules and act as drug carrier systems. In the present work, a new type of thermo/pH sensitive NG comprising salep modified graphene oxide (SMGO) with branched N-isopropylacrylamide (NIPAM) and acrylic acid (AA) was prepared. The SMGO/P(NIPAM-co-AA) NGs exhibited nanoporous structure and spherical particles with diameters about 82 nm as characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The samples were also characterized by Fourier transform infrared spectroscopy (FT-IR) and thermo gravimetric analysis (TGA) to further confirm about the formation of NGs. Doxorubicin (DOX) loaded SMGO/P(NIPAM-co-AA) NGs showed thermo/pH dependent releasing behavior: slow drug release at neutral pH and lower temperature but increased significantly in acidic pH and higher temperature, without any burst release. In addition, the NGs exhibited no effect on the cell viability in the tested concentration range up to 410 μg/mL and drug release systems enhanced toxicity to HeLa cells when compared to the equivalent dose of the free drug. Overall, our results put forth NGs as potential candidates in the development of a new nanocarrier for anti-cancer drug delivery. - Highlights: • A novel thermo/pH sensitive nanogels (NGs) was successfully synthesized. • NGs showed high loading capacity for DOX drug and slow drug release at neutral pH. • NGs exhibited no effect on the cell viability in the tested concentration range.

  16. The pharmacokinetic study of rutin in rat plasma based on an electrochemically reduced graphene oxide modified sensor

    Directory of Open Access Journals (Sweden)

    Pei Zhang

    2016-04-01

    Full Text Available An electrochemical method based on a directly electrochemically reduced graphene oxide (ERGO film coated on a glassy carbon electrode (GCE was developed for the rapid and convenient determination of rutin in plasma. ERGO was modified on the surface of GCE by one-step electro-deposition method. Electrochemical behavior of rutin on ERGO/GCE indicated that rutin underwent a surface-controlled quasi-reversible process and the electrochemical parameters such as charge transfer coefficient (α, electron transfer number (n and electrode reaction standard rate constant (ks were 0.53, 2 and 3.4 s−1, respectively. The electrochemical sensor for rutin in plasma provided a wide linear response range of 4.70×10−7−1.25×10−5 M with the detection limit (s/n=3 of 1.84×10−8 M. The assay was successfully used to the pharmacokinetic study of rutin. The pharmacokinetic parameters such as elimination rate half-life (t1/2, area under curve (AUC, and plasma clearance (CL were calculated to be 3.345±0.647 min, 5750±656.0 µg min/mL, and 5.891±0.458 mL/min/kg, respectively. The proposed method utilized a small sample volume of 10 μL and had no complicated sample pretreatment (without deproteinization, which was simple, eco-friendly, and time- and cost-efficient for rutin pharmacokinetic studies.

  17. Glassy carbon electrode modified with 7,7,8,8-tetracyanoquinodimethane and graphene oxide triggered a synergistic effect: Low-potential amperometric detection of reduced glutathione.

    Science.gov (United States)

    Yuan, Baiqing; Xu, Chunying; Zhang, Renchun; Lv, Donghui; Li, Sujuan; Zhang, Daojun; Liu, Lin; Fernandez, Carlos

    2017-10-15

    A sensitive electrochemical sensor based on the synergistic effect of 7,7,8,8-tetracyanoquinodimethane (TCNQ) and graphene oxide (GO) for low-potential amperometric detection of reduced glutathione (GSH) in pH 7.2 phosphate buffer solution (PBS) has been reported. This is the first time that the combination of GO and TCNQ have been successfully employed to construct an electrochemical sensor for the detection of glutathione. The surface of the glassy carbon electrode (GCE) was modified by a drop casting using TCNQ and GO. Cyclic voltammetric measurements showed that TCNQ and GO triggered a synergistic effect and exhibited an unexpected electrocatalytic activity towards GSH oxidation, compared to GCE modified with only GO, TCNQ or TCNQ/electrochemically reduced GO. Three oxidation waves for GSH were found at -0.05, 0.1 and 0.5V, respectively. Amperometric techniques were employed to detect GSH sensitively using a GCE modified with TCNQ/GO at -0.05V. The electrochemical sensor showed a wide linear range from 0.25 to 124.3μM and 124.3μM to 1.67mM with a limit of detection of 0.15μM. The electroanalytical sensor was successfully applied towards the detection of GSH in an eye drop solution. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Zinc Tantalum Oxynitride (ZnTaO2N Photoanode Modified with Cobalt Phosphate Layers for the Photoelectrochemical Oxidation of Alkali Water

    Directory of Open Access Journals (Sweden)

    Prabhakarn Arunachalam

    2018-01-01

    Full Text Available Photoanodes fabricated by the electrophoretic deposition of a thermally prepared zinc tantalum oxynitride (ZnTaO2N catalyst onto indium tin oxide (ITO substrates show photoactivation for the oxygen evolution reaction (OER in alkaline solutions. The photoactivity of the OER is further boosted by the photodeposition of cobalt phosphate (CoPi layers onto the surface of the ZnTaO2N photoanodes. Structural, morphological, and photoelectrochemical (PEC properties of the modified ZnTaO2N photoanodes are studied using X-ray diffraction (XRD, scanning electron microscopy (SEM, ultraviolet visible (UV−Vis diffuse reflectance spectroscopy, and electrochemical techniques. The presence of the CoPi layer significantly improved the PEC performance of water oxidation in an alkaline sulphate solution. The photocurrent-voltage behavior of the CoPi-modified ZnTaO2N anodes was improved, with the influence being more prominent at lower oxidation potentials. A stable photocurrent density of about 2.3 mA·cm−2 at 1.23 V vs. RHE was attained upon visible light illumination. Relative to the ZnTaO2N photoanodes, an almost three-fold photocurrent increase was achieved at the CoPi/ZnTaO2N photoelectrode. Perovskite-based oxynitrides are modified using an oxygen-evolution co-catalyst of CoPi, and provide a new dimension for enhancing the photoactivity of oxygen evolution in solar-assisted water-splitting reactions.

  19. Experimental and theoretical study on the oxidation mechanism of dopamine in n-octyl pyridinium based ionic liquids–carbon paste modified electrodes

    International Nuclear Information System (INIS)

    Díaz, Carlos; García, Camilo; Iturriaga-Vásquez, Patricio; Aguirre, Maria Jesús; Muena, Juan Pablo; Contreras, Renato; Ormazábal-Toledo, Rodrigo; Isaacs, Mauricio

    2013-01-01

    This work describes the influence of n-octyl pyridinium cations based ionic liquids–carbon paste modified electrodes on the oxidation mechanism of dopamine. Ionic liquids formed by hexafluorophosphate anion and n-octyl pyridinium [R-OPy] + ; R = CH 3 , H, CF 3 , where ionic liquids containing CH 3 and CF 3 are new products, were synthesized and characterized. Modified carbon paste electrodes with these salts were characterized by electrochemical impedance spectroscopy and cyclic voltammetry. Electrochemical oxidation of dopamine was studied in PBS buffer solution at pH = 7.4. The influence of the ionic liquids in the oxidation of dopamine was studied by cyclic voltammetry and rotating disk electrode. The results show that typical carbon paste electrode presents an electrochemical/chemical mechanism; whereas [OPy]PF 6 and [CF 3 -OPy]PF 6 modified electrodes present an electrochemical/chemical/electrochemical mechanism. The experimental study is complemented with a theoretical analysis of substituent effects in terms of the molecular electrostatic potential, Mulliken population analysis and second order perturbation theory probed at the cation moiety of the IL. These indices consistently show an electron density accumulation at the ipso position of the pyridinium moiety of the IL that is in agreement with the electrochemical characterization

  20. Simultaneous determination of L-tyrosine and caffeine based on their electrocatalytic oxidation at a 4-tert-butylcalix[6] arene-modified carbon paste electrode.

    Science.gov (United States)

    Srivastava, Ashwini K; Gaichore, Reena R

    2013-01-01

    Simultaneous determination of L-tyrosine and caffeine was performed at a carbon paste electrode modified with 4-tert-butylcalix[6]arene and in situ Ni2+ ions. Surface characterization of the electrode was carried out by means of scanning electron microscopy. Electrochemical impedance diagnosis revealed that oxidation of both molecules is kinetically facile on the modified electrode. The electrochemical behavior of both molecules was studied using cyclic voltammetry, and further quantified using differential pulse voltammetry (DPV). The results revealed a high sensitivity for their simultaneous detection. DPV allowed simultaneous detection of L-tyrosine and caffeine in the range of 10(-6) to 10(-3) M, with LODs of 2.19 x 10(-7) and 4.03 x 10(-7) M, respectively. The modified electrode was used for individual determination of L-tyrosine and caffeine in various pharmaceutical formulations and simultaneous monitoring in human body fluids.

  1. Oxidation Behavior of TiAl-Based Alloy Modified by Double-Glow Plasma Surface Alloying with Cr-Mo

    Science.gov (United States)

    Wei, Xiangfei; Zhang, Pingze; Wang, Qiong; Wei, Dongbo; Chen, Xiaohu

    2017-07-01

    A Cr-Mo alloyed layer was prepared on a TiAl-based alloy using plasma surface alloying technique. The isothermal oxidation kinetics of the untreated and treated samples was examined at 850 °C. The microstructure and phase composition of the alloyed layer were analyzed by scanning electron microscope (SEM), energy dispersive spectrometer (EDS) and X-ray powder diffraction (XRD). The morphology and constituent of the oxide scales were also analyzed. The results indicated that the oxidation resistance of TiAl was improved significantly after the alloying treatment. The oxide scale eventually became a mixture of Al2O3, Cr2O3 and TiO2. The oxide scale was dense and integrated throughout the oxidation process. The improvement was mainly owing to the enhancing of scale adhesion and the preferential oxidation of aluminum brought by the alloying effect for TiAl-based alloy.

  2. High performance dye-sensitized solar cells using graphene modified fluorine-doped tin oxide glass by Langmuir–Blodgett technique

    Energy Technology Data Exchange (ETDEWEB)

    Roh, Ki-Min [Rare Metals Research Center, Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350 (Korea, Republic of); Jo, Eun-Hee; Chang, Hankwon [Rare Metals Research Center, Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350 (Korea, Republic of); Nanomaterials Science and Engineering Major, University of Science and Technology, Daejeon 305-350 (Korea, Republic of); Han, Tae Hee [Department of Organic and Nano Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Jang, Hee Dong, E-mail: hdjang@kigam.re.kr [Rare Metals Research Center, Korea Institute of Geoscience and Mineral Resources, Daejeon 305-350 (Korea, Republic of); Nanomaterials Science and Engineering Major, University of Science and Technology, Daejeon 305-350 (Korea, Republic of)

    2015-04-15

    Since the introduction of dye-sensitized solar cells (DSSCs) with low fabrication cost and high power conversion efficiency, extensive studies have been carried out to improve the charge transfer rate and performance of DSSCs. In this paper, we present DSSCs that use surface modified fluorine-doped tin oxide (FTO) substrates with reduced graphene oxide (r-GO) sheets prepared using the Langmuir–Blodgett (LB) technique to decrease the charge recombination at the TiO{sub 2}/FTO interface. R-GO sheets were excellently attached on FTO surface without physical deformations such as wrinkles; effects of the surface coverage of r-GO on the DSSC performance were also investigated. By using graphene modified FTO substrates, the resistance at the interface of TiO{sub 2}/FTO was reduced and the power conversion efficiency was increased to 8.44%. - Graphical abstract: DSSCs with graphene modified FTO glass were fabricated with the Langmuir Blodgett technique. GO sheets were transferred to FTO at various surface pressures in order to change the surface density of graphene and the highest power conversion efficiency of the DSSC was 8.44%. - Highlights: • By LB technique, r-GO sheets were coated on FTO without physical deformation. • DSSCs were fabricated with, r-GO modified FTO substrates. • With surface modification by r-GO, the interface resistance of DSSC decreased. • Maximum PCE of the DSSC was increased up to 8.44%.

  3. Effective improvement of interface modified strontium titanate based solid oxide fuel cell anodes by infiltration with nano-sized palladium and gadolinium-doped cerium oxide

    DEFF Research Database (Denmark)

    Abdul Jabbar, Mohammed Hussain; Høgh, Jens Valdemar Thorvald; Zhang, Wei

    2013-01-01

    The development of low temperature solid oxide fuel cell (SOFC) anodes by infiltration of Pd/Gd-doped cerium oxide (CGO) electrocatalysts in Nb-doped SrTiO3 (STN) backbones has been investigated. Modification of the electrode/electrolyte interface by thin layer of spin-coated CGO (400-500 nm) con...

  4. Evaluation of ischemia-modified albumin level and parameters related with oxidative stress in early onset androgenetic alopecia

    Directory of Open Access Journals (Sweden)

    Hülya Nazik

    2017-12-01

    Full Text Available Background and Design: Ischemia-modified albumin (IMA is a biomarker, which is an indicator of ischemia and oxidative stress, and measured by the albumin cobalt binding test. Androgenetic alopecia (AGA is the most important cause of hair loss in males. Hair loss that is affected by androgenic hormones, age, and ethnic, family and environmental factors, may lead to psychological, social and physical problems in some individuals. The aim of the present study was to investigate the factors affecting AGA, and the correlation between AGA and IMA. Materials and Methods: Fifty male patients with AGA aged 18-35 years and 30 males of similar age without AGA were included in the study. Patients with AGA stage 3 or higher were included in the study group. Blood samples were collected after a 12-hour fasting period. Blood glucose, total cholesterol, high-density lipoprotein (HDL, low-density lipoprotein (LDL, triglyceride, insulin, testosterone, dehydroepiandrosterone-sulfate (DHEA-S, and albumin levels were analyzed using an autoanalyzer. IMA values were evaluated using a MINDRAY BS 2000 autoanalyzer. Results: A total of 80 individuals were included in the study. There was no significant difference in mean age (p=0.179, body mass index (p=0.847, DHEA-S (p=0.247, testosterone (p=0.874, lipid profile [triglyceride (p=0.086, total cholesterol (p=0.492, HDL (p=0.993, LDL (p=0.544], insulin resistance (p=0.399 and IMA (p=0.976 between study group and control group. Additionally, a family history of alopecia was found to be significantly higher in the study group (p=0.000. Moreover, there was a positive correlation between AGA grade and insulin resistance (r=0.296; p=0.037. Conclusion: AGA, which leads to many cosmetic and psychosocial problems, was more frequent in individuals with a family history of alopecia; also, there was a positive correlation between AGA stage and insulin resistance. On the other hand, there was no significant correlation between AGA and

  5. Physicochemical properties and in vitro cytocompatibility of modified titanium surfaces prepared via micro-arc oxidation with different calcium concentrations

    International Nuclear Information System (INIS)

    Wu, Sui-Dan; Zhang, Hui; Dong, Xu-Dong; Ning, Cheng-Yun; Fok, Alex S.L.; Wang, Yan

    2015-01-01

    Highlights: • MAO coating improves the surface characteristics and cytocompatibility of titanium. • Composition of MAO coating varies with the electrolyte concentration. • MAO coating properties can be optimized by adjusting the electrolyte concentration. • Higher CA concentration contributes to more favorable MAO coating cytocompatibility. - Abstract: Objective: To explore the effect of calcium concentration in the electrolyte solution on the physicochemical properties and biocompatibility of coatings formed by micro-arc oxidation (MAO) on titanium surfaces. Methods: The surfaces of pure titanium plates were modified by MAO in an electrolytic solution containing calcium acetate (CA; C 4 H 6 CaO 4 ) at concentrations of 0.05, 0.1, 0.2, or 0.3 M and β-glycerophosphate disodium salt pentahydrate (β-GP; C 3 H 7 Na 2 O 6 P·5H 2 O) at a fixed concentration of 0.02 M. Surface topography, elemental characteristics, phase composition, and roughness were investigated by scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, and a surface roughness tester, respectively. To assess the cytocompatibility and osteoinductivity of the surfaces, MC3T3-E1 preosteoblasts were cultured on the surfaces in vitro, and cell morphology, adhesion, proliferation, and differentiation were observed. Results: The porous MAO coating was composed primarily of TiO 2 rutile and anatase. The amount of TiO 2 rutile, the Ca/P ratio, and the surface roughness of the MAO coating increased with increasing CA concentration in the electrolyte solution. Ca 3 (PO 4 ) 2 , CaCO 3 , and CaTiO 3 were formed on MAO-treated surfaces prepared with CA concentrations of 0.2 and 0.3 M. Cell proliferation and differentiation increased with increasing CA concentration, with MC3T3-E1 cells exhibiting favorable morphologies for bone–implant integration. Conclusions: MAO coating improves the surface characteristics and cytocompatibility of titanium for osseointegration. Higher CA

  6. Adsorption of mercury ions from wastewater by a hyperbranched and multi-functionalized dendrimer modified mixed-oxides nanoparticles.

    Science.gov (United States)

    Arshadi, M; Mousavinia, F; Khalafi-Nezhad, A; Firouzabadi, H; Abbaspourrad, A

    2017-11-01

    In this paper, a novel heterogeneous nanodendrimer with generation of G2.0 was prepared by individual grafting of diethylenetriamine, triazine and l-cysteine methyl ester on the modified aluminum-silicate mixed oxides as a potent adsorbent of Hg(II) ions from aqueous media. The prepared nanodendrimer was characterized by nuclear magnetic resonance spectrum ( 1 H NMR and 13 C NMR), Fourier transform infrared spectroscopy (FT-IR), Diffuse reflectance UV-Vis spectroscopy (DR UV-Vis), zeta potential (ζ), inductively coupled plasma atomic emission spectroscopy (ICP-AES), transmission electron microscopy (TEM), scanning electron microscopy (SEM), nitrogen adsorption experiments at -196°C and elemental analysis. Equilibrium and kinetic models for Hg(II) ions removal were used by investigating the effect of the contact time, adsorbent dosage, initial Hg(II) ions concentrations, effect of solution's temperature, interfering ions, and initial pH. The contact time to approach equilibrium for higher removal was 6min (3232mgg -1 ). The removal of Hg(II) ions has been assessed in terms of pseudo-first- and -second-order kinetics, and the Freundlich, Langmuir and Sips isotherms models have also been applied to the equilibrium removal data. The removal kinetics followed the mechanism of the pseudo-second order equation, where the chemical sorption is the rate-limiting step of removal process and not involving mass transfer in solution, which was further proved by several techniques such as zeta potential, FT-IR and DS UV-vis. The thermodynamic parameters (ΔG, ΔH and ΔS) implied that the removal of mercury ions was feasible, spontaneous and chemically exothermic in nature between 15 and 80°C. The nanodendrimer indicated high reusability due to its high removal ability after 15 adsorption-desorption runs. The adsorption mechanisms of Hg(II) ions onto the nanodendrimer was further studied by diverse techniques such as FTIR, EDS, zeta potential, DR UV-Vis spectroscopy and SEM

  7. Physicochemical properties and in vitro cytocompatibility of modified titanium surfaces prepared via micro-arc oxidation with different calcium concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Sui-Dan; Zhang, Hui [Guanghua School of Stomatology, Hospital of Stomatology, Guangdong Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055 (China); Dong, Xu-Dong [Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver, BC V6T 1Z3 (Canada); Ning, Cheng-Yun [College of Material Science and Engineering, South China University of Technology, Guangzhou 510641 (China); Fok, Alex S.L. [Minnesota Dental Research Center of Biomaterials and Biomechanics, School of Dentistry, University of Minnesota, Minneapolis, MN 55414 (United States); Wang, Yan, E-mail: wyan65@163.com [Guanghua School of Stomatology, Hospital of Stomatology, Guangdong Key Laboratory of Stomatology, Sun Yat-sen University, Guangzhou 510055 (China)

    2015-02-28

    Highlights: • MAO coating improves the surface characteristics and cytocompatibility of titanium. • Composition of MAO coating varies with the electrolyte concentration. • MAO coating properties can be optimized by adjusting the electrolyte concentration. • Higher CA concentration contributes to more favorable MAO coating cytocompatibility. - Abstract: Objective: To explore the effect of calcium concentration in the electrolyte solution on the physicochemical properties and biocompatibility of coatings formed by micro-arc oxidation (MAO) on titanium surfaces. Methods: The surfaces of pure titanium plates were modified by MAO in an electrolytic solution containing calcium acetate (CA; C{sub 4}H{sub 6}CaO{sub 4}) at concentrations of 0.05, 0.1, 0.2, or 0.3 M and β-glycerophosphate disodium salt pentahydrate (β-GP; C{sub 3}H{sub 7}Na{sub 2}O{sub 6}P·5H{sub 2}O) at a fixed concentration of 0.02 M. Surface topography, elemental characteristics, phase composition, and roughness were investigated by scanning electron microscopy, energy-dispersive X-ray analysis, X-ray diffraction, and a surface roughness tester, respectively. To assess the cytocompatibility and osteoinductivity of the surfaces, MC3T3-E1 preosteoblasts were cultured on the surfaces in vitro, and cell morphology, adhesion, proliferation, and differentiation were observed. Results: The porous MAO coating was composed primarily of TiO{sub 2} rutile and anatase. The amount of TiO{sub 2} rutile, the Ca/P ratio, and the surface roughness of the MAO coating increased with increasing CA concentration in the electrolyte solution. Ca{sub 3}(PO{sub 4}){sub 2}, CaCO{sub 3}, and CaTiO{sub 3} were formed on MAO-treated surfaces prepared with CA concentrations of 0.2 and 0.3 M. Cell proliferation and differentiation increased with increasing CA concentration, with MC3T3-E1 cells exhibiting favorable morphologies for bone–implant integration. Conclusions: MAO coating improves the surface characteristics and

  8. No effect on oxidative stress biomarkers by modified intakes of polyunsaturated fatty acids or vegetables and fruit

    DEFF Research Database (Denmark)

    Freese, R.; Dragsted, Lars Ove; Loft, Steffen

    2008-01-01

    Diet may both increase and decrease oxidative stress in the body. We compared the effects of four strictly controlled isocaloric diets with different intakes of polyunsaturated fatty acids (PUFA, 11 or 3% of energy) and vegetables and fruit (total amount of vegetables and fruit 516 or 1059 g/10 MJ......) on markers associated with oxidative stress in 77 healthy volunteers (19-52 years). Plasma protein carbonyls (2-aminoadipic semialdehyde residues) and whole-body DNA and nucleotide oxidation (urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine excretion) tended to decrease in all treatment groups with no differences...... in their effects on markers associated with oxidative stress....

  9. Phosphate Adsorption using Modified Iron Oxide-based Sorbents in Lake Water: Kinetics, Equilibrium, and Column Tests

    Science.gov (United States)

    Adsorption behavior of Bayoxide ® E33 (E33) and three E33-modified sorbents for the removal of phosphate from lake water was investigated in this study. E33-modified sorbents were synthesized by coating with manganese (E33/Mn) and silver (E33/AgI and E33/AgII) nanoparticles. Adso...

  10. Improvement of the electrochromic response of a low-temperature sintered dye-modified porous electrode using low-resistivity indium tin oxide nanoparticles

    International Nuclear Information System (INIS)

    Watanabe, Yuichi; Suemori, Kouji; Hoshino, Satoshi

    2016-01-01

    An indium tin oxide (ITO) nanoparticle-based porous electrode sintered at low temperatures was investigated as a transparent electrode for electrochromic displays (ECDs). The electrochromic (EC) response of the dye-modified ITO porous electrode sintered at 150 °C, which exhibited a generally low resistivity, was markedly superior to that of a conventional dye-modified TiO 2 porous electrode sintered at the same temperature. Moreover, the EC characteristics of the dye-modified ITO porous electrode sintered at 150 °C were better than those of the high-temperature (450 °C) sintered conventional dye-modified TiO 2 porous electrode. These improvements in the EC characteristics of the dye-modified ITO porous electrode are attributed to its lower resistivity than that of the TiO 2 porous electrodes. In addition to its sufficiently low resistivity attained under the sintering conditions required for flexible ECD applications, the ITO porous film had superior visible-light transparency and dye adsorption capabilities. We conclude that the process temperature, resistivity, optical transmittance, and dye adsorption capability of the ITO porous electrode make it a promising transparent porous electrode for flexible ECD applications.

  11. Utilization of reduced graphene oxide/cadmium sulfide-modified carbon cloth for visible-light-prompt photoelectrochemical sensor for copper (II) ions

    Energy Technology Data Exchange (ETDEWEB)

    Foo, C.Y. [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Lim, H.N., E-mail: janetlimhn@gmail.com [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Functional Device Laboratory, Institute of Advance Technology, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Pandikumar, A.; Huang, N.M. [Low Dimensional Materials Research Centre, Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Ng, Y.H. [Particles and Catalysis Research Group, School of Chemical Engineering, The University of New South Wales, NSW 2052 (Australia)

    2016-03-05

    Highlights: • CdS/rGO-modified carbon cloth for detection of copper(II). • Two linear detection range of 0.1 μM to 1.0 μM and 1.0 μM to 40.0 μM. • Detection limit of 0.05 μM and 0.50 μM. - Abstract: A newly developed CdS/rGO/CC electrode was prepared based on a flexible carbon cloth (CC) substrate with cadmium sulfide (CdS) nanoparticles and reduced graphene oxide (rGO). The CdS was synthesized using an aerosol-assisted chemical vapor deposition (AACVD) method, and the graphene oxide was thermally reduced on the modified electrode surface. The existence of rGO in the CdS-modified electrode increased the photocurrent intensity of the CdS/rGO/CC-modified electrode by three orders of magnitude, compared to that of the CdS/ITO electrode and two orders of magnitude higher than the CdS/CC electrode. A new visible-light-prompt photoelectrochemical sensor was developed based on the competitive binding reaction of Cu{sup 2+} and CdS on the electrode surface. The results showed that the effect of the Cu{sup 2+} on the photocurrent response was concentration-dependent over the linear ranges of 0.1–1.0 μM and 1.0–40.0 μM with a detection limit of 0.05 μM. The results of a selectivity test showed that this modified electrode has a high response toward Cu{sup 2+} compared to other heavy metal ions. The proposed CdS/rGO/CC electrode provided a significantly high potential current compared to other reported values, and could be a practical tool for the fast, sensitive, and selective determination of Cu{sup 2+}.

  12. Superior catalytic properties in aerobic oxidation of olefins over Au nanoparticles on pyrrolidone-modified SBA-15

    Czech Academy of Sciences Publication Activity Database

    Wang, L.; Wang, H.; Hapala, Prokop; Zhu, L.; Ren, L.; Meng, X.; Lewis, J.P.; Xiao, F.-S.

    2011-01-01

    Roč. 281, č. 1 (2011), s. 30-39 ISSN 0021-9517 Institutional research plan: CEZ:AV0Z10100521 Keywords : Au nanoparticles * pyrrolidone * cyclohexene oxidation * styrene oxidation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 6.002, year: 2011

  13. Fabrication of sensitive enzymatic biosensor based on multi-layered reduced graphene oxide added PtAu nanoparticles-modified hybrid electrode.

    Directory of Open Access Journals (Sweden)

    Md Faruk Hossain

    Full Text Available A highly sensitive amperometric glucose sensor was developed by immobilization of glucose oxidase (GOx onto multi-layer reduced graphene oxide (MRGO sheets decorated with platinum and gold flower-like nanoparticles (PtAuNPs modified Au substrate electrode. The fabricated MRGO/PtAuNPs modified hybrid electrode demonstrated high electrocatalytic activities toward oxidation of H2O2, to which it had a wide linear response that ranged from 0.5 to 8 mM (R2 = 0.997, and high sensitivity of 506.25 μA/mMcm2. Furthermore, glucose oxidase-chitosan composite and cationic polydiallyldimethylammonium chloride (PDDA were assembled by a casting method on the surface of MRGO/PtAuNPs modified electrode. This as-fabricated hybrid biosensor electrode exhibited high electrocatalytic activity for the detection of glucose in PBS. It demonstrated good analytical properties in terms of a low detection limit of 1 μM (signal-to-noise ratio of 3, short response time (3 s, high sensitivity (17.85 μA/mMcm2, and a wide linear range (0.01-8 mM for glucose sensing. These results reveal that the newly developed sensing electrode offers great promise for new type enzymatic biosensor applications.

  14. Electrochemical behavior and voltammetric determination of acetaminophen based on glassy carbon electrodes modified with poly(4-aminobenzoic acid)/electrochemically reduced graphene oxide composite films.

    Science.gov (United States)

    Zhu, Wencai; Huang, Hui; Gao, Xiaochun; Ma, Houyi

    2014-12-01

    Poly(4-aminobenzoic acid)/electrochemically reduced graphene oxide composite film modified glassy carbon electrodes (4-ABA/ERGO/GCEs) were fabricated by a two-step electrochemical method. The electrochemical behavior of acetaminophen at the modified electrode was investigated by means of cyclic voltammetry. The results indicated that 4-ABA/ERGO composite films possessed excellent electrocatalytic activity towards the oxidation of acetaminophen. The electrochemical reaction of acetaminophen at 4-ABA/ERGO/GCE is proved to be a surface-controlled process involving the same number of protons and electrons. The voltammetric determination of acetaminophen performed with the 4-ABA/ERGO modified electrode presents a good linearity in the range of 0.1-65 μM with a low detection limit of 0.01 μM (S/N=3). In the case of using the 4-ABA/ERGO/GCE, acetaminophen and dopamine can be simultaneously determined without mutual interference. Furthermore, the 4-ABA/ERGO/GCE has good reproducibility and stability, and can be used to determine acetaminophen in tablets. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Fabrication of sensitive enzymatic biosensor based on multi-layered reduced graphene oxide added PtAu nanoparticles-modified hybrid electrode.

    Science.gov (United States)

    Hossain, Md Faruk; Park, Jae Y

    2017-01-01

    A highly sensitive amperometric glucose sensor was developed by immobilization of glucose oxidase (GOx) onto multi-layer reduced graphene oxide (MRGO) sheets decorated with platinum and gold flower-like nanoparticles (PtAuNPs) modified Au substrate electrode. The fabricated MRGO/PtAuNPs modified hybrid electrode demonstrated high electrocatalytic activities toward oxidation of H2O2, to which it had a wide linear response that ranged from 0.5 to 8 mM (R2 = 0.997), and high sensitivity of 506.25 μA/mMcm2. Furthermore, glucose oxidase-chitosan composite and cationic polydiallyldimethylammonium chloride (PDDA) were assembled by a casting method on the surface of MRGO/PtAuNPs modified electrode. This as-fabricated hybrid biosensor electrode exhibited high electrocatalytic activity for the detection of glucose in PBS. It demonstrated good analytical properties in terms of a low detection limit of 1 μM (signal-to-noise ratio of 3), short response time (3 s), high sensitivity (17.85 μA/mMcm2), and a wide linear range (0.01-8 mM) for glucose sensing. These results reveal that the newly developed sensing electrode offers great promise for new type enzymatic biosensor applications.

  16. Impedimetric PSA aptasensor based on the use of a glassy carbon electrode modified with titanium oxide nanoparticles and silk fibroin nanofibers.

    Science.gov (United States)

    Benvidi, Ali; Banaei, Maryam; Tezerjani, Marzieh Dehghan; Molahosseini, Hosein; Jahanbani, Shahriar

    2017-12-14

    This article describes an impedimetric aptasensor for the prostate specific antigen (PSA), a widely accepted prostate cancer biomarker. A glassy carbon electrode (GCE) was modified with titanium oxide nanoparticles (TiO 2 ) and silk fibroin nanofiber (SF) composite. The aptasensor was obtained by immobilizing a PSA-binding aptamer on the AuNP-modified with 6-mercapto-1-hexanol. The single fabrication steps were characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The assay has two linear response ranges (from 2.5 fg.mL -1 to 25 pg.mL -1 , and from 25 pg.mL -1 to 25 ng.mL -1 ) and a 0.8 fg.mL -1 detection limit. After optimization of experimental conditions, the sensor is highly selective for PSA over bovine serum albumin and lysozyme. It was successfully applied to the detection of PSA in spiked serum samples. Graphical abstract Schematic of the fabrication of an aptasensor for the prostate specific antigen (PSA). It is based on the use of a glassy carbon electrode modified with gold nanoparticles and titanium oxide-silk fibroin. The immobilization process of aptamer and interaction with PSA were followed by electrochemical impedance spectroscopy technique.

  17. Demonstration of the lack of cytotoxicity of unmodified and folic acid modified graphene oxide quantum dots, and their application to fluorescence lifetime imaging of HaCaT cells.

    Science.gov (United States)

    Goreham, Renee V; Schroeder, Kathryn L; Holmes, Amy; Bradley, Siobhan J; Nann, Thomas

    2018-01-24

    The authors describe the synthesis of water-soluble and fluorescent graphene oxide quantum dots via acid exfoliation of graphite nanoparticles. The resultant graphene oxide quantum dots (GoQDs) were then modified with folic acid. Folic acid receptors are overexpressed in cancer cells and hence can bind to functionalized graphene oxide quantum dots. On excitation at 305 nm, the GoQDs display green fluorescence with a peak wavelength at ~520 nm. The modified GoQDs are non-toxic to macrophage cells even after prolonged exposure and high concentrations. Fluorescence lifetime imaging and multiphoton microscopy was used (in combination) to image HeCaT cells exposed to GoQDs, resulting in a superior method for bioimaging. Graphical abstract Schematic representation of graphene oxide quantum dots, folic acid modified graphene oxide quantum dots (red), and the use of fluorescence lifetime to discriminate against green auto-fluorescence of HeCaT cells.

  18. Pre-treatments applied to oxidized aluminum surfaces to modify the interfacial bonding with bis-1,2-(triethoxysilyl)ethane (BTSE)

    International Nuclear Information System (INIS)

    Teo, M.; Kim, J.; Wong, P.C.; Wong, K.C.; Mitchell, K.A.R.

    2005-01-01

    A remote microwave-generated H 2 plasma and heating to 250 deg. C were separately used to modify high-purity oxidized aluminum surfaces and to assess whether these treatments can help enhance adhesion with bis-1,2-(triethoxysilyl)ethane (BTSE) coatings. Different initial oxide surfaces were considered, corresponding to the native oxide and to surfaces formed by the Forest Products Laboratory (FPL) treatment applied for either 15 or 60 min. BTSE is applied from solution at pH 4, and competing processes of etching, protonation (to form OH groups) and coupling (to form Al-O-Si interfacial bonds) occur at the solid-liquid interface. Scanning electron microscopy (SEM) was used to determine how the topographies of the modified Al surfaces changed with the different pre-treatments and with exposure to a buffer solution of pH 4. Secondary-ion mass spectrometry (SIMS) was used to determine the direct amount of Al-O-Si interfacial bonds by measuring the ratio of peak intensities 71-70 amu, while X-ray photoelectron spectroscopy (XPS) was used to determine the overall strength of the silane coating adhesion by measuring the Si 2p signals before and after application of an ultrasonic rinse to the coated sample. Measured Al 2p and O 1s spectra helped assess how the different pre-treatments modified the various Al oxidized surfaces prior to BTSE coating. Pre-treated samples that showed increased Al-O-Si bonding after BTSE coating corresponded to surfaces, which did not show evidence of significant etching after exposure to a pH 4 environment. This suggests that such surfaces are more receptive to the coupling reaction during exposure to the BTSE coating solution. These surfaces include all H 2 plasma-treated samples, the heated native oxide and the sample that only received the 15 min FPL treatment. In contrast, other surfaces that show evidence of etching in pH 4 environments are samples that received lower amounts of Al-O-Si interfacial bonding. Overall, heating improved the

  19. Low-temperature abatement of toluene over Mn-Ce oxides catalysts synthesized by a modified hydrothermal approach

    Science.gov (United States)

    Du, Jinpeng; Qu, Zhenping; Dong, Cui; Song, Lixin; Qin, Yuan; Huang, Na

    2018-03-01

    Mn-Ce oxides catalysts were synthesized by a novel method combining redox-precipitation and hydrothermal approach. The results indicate that the ratio between manganese and cerium plays a crucial role in the formation of catalysts, and the textual properties as well as catalytic activity are remarked affected. Mn0.6Ce0.4O2 possesses a predominant catalytic activity in the oxidation of toluene, over 70% of toluene is converted at 200 °C, and the complete conversion temperature is 210 °C. The formation of Mn-Ce solid solution markedly improves the surface area as well as pore volume of Mn-Ce oxide catalyst, and Mn0.6Ce0.4O2 possesses the largest surface area of 298.5 m2/g. The abundant Ce3+ and Mn3+ on Mn0.6Ce0.4O2 catalyst facilitate the formation of oxygen vacancies, and improve the transfer of oxygen in the catalysts. Meanwhile, it is found that cerium in Mn-Ce oxide plays a key role in the adsorption of toluene, while manganese is proved to be crucial in the oxidation of toluene, the cooperation between manganese and cerium improves the catalytic reaction process. In addition, the reaction process is investigated by in situ DRIFT measurement, and it is found that the adsorbed toluene could be oxidized to benzyl alcohol as temperature rises around 80-120 °C that can be further be oxidized to benzoic acid. Then benzoic acid could be decomposed to formate and/or carbonate species as temperature rises to form CO2 and H2O. In addition, the formed by-product phenol could be further oxidized into CO2 and H2O when the temperature is high enough.

  20. Simultaneous oxidative conversion and co/sub 2/ reforming of methane to syngas over modified Ni/Al/sub 2/O/sub 3/ catalysts

    International Nuclear Information System (INIS)

    Eli, W.

    2013-01-01

    A series of Ni/Al/sub 2/O/sub 3/ and modified Ni-M/Al/sub 2/O/sub 3/ (MLa, Na, K, Ca and Ba) catalysts have been prepared and characterized by XRD, BET, XPS, TGA, TEM and SEM. The performance of these catalysts for simultaneous oxidative conversion and CO/sub 2/ reforming of methane to syngas was evaluated using a fixed-bed reactor. The results indicated that the catalytic activity of Ni/Al/sub 2/O/sub 3/ increased with Ni loading, and reached maximum at 12% Ni loading. The La-modified Ni/Al/sub 2/O/sub 3/ exhibited an excellent catalytic activity and stability within 20 h as compared with unmodified and Na-modified ones. It was found that the addition of La decreased the particle size of nickel, thus increased the Ni dispersion accordingly as indicated by the characterization data. The catalytic activity of Na-modified Ni/Al/sub 2/O/sub 3/ decreased obviously only after 6 h of reaction due to aggregation of metallic Ni particles. Hence, it was suggested that the sintering of Ni particles dominated the catalyst deactivation during the catalytic reaction process. (author)

  1. Effects of Calcination Temperature and Acid-Base Properties on Mixed Potential Ammonia Sensors Modified by Metal Oxides

    Science.gov (United States)

    Satsuma, Atsushi; Katagiri, Makoto; Kakimoto, Shiro; Sugaya, Satoshi; Shimizu, Kenichi

    2011-01-01

    Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ) as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 °C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO3, Bi2O3 and V2O5, while the use of WO3, Nb2O5 and MgO was not effective. The melting points of the former group were below 820 °C, while those of the latter group were higher than 1,000 °C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO3 > Bi2O3 > V2O5, which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified. PMID:22319402

  2. Effects of Calcination Temperature and Acid-Base Properties on Mixed Potential Ammonia Sensors Modified by Metal Oxides

    Directory of Open Access Journals (Sweden)

    Kenichi Shimizu

    2011-02-01

    Full Text Available Mixed potential sensors were fabriated using yttria-stabilized zirconia (YSZ as a solid electrolyte and a mixture of Au and various metal oxides as a sensing electrode. The effects of calcination temperature ranging from 600 to 1,000 °C and acid-base properties of the metal oxides on the sensing properties were examined. The selective sensing of ammonia was achieved by modification of the sensing electrode using MoO3, Bi2O3 and V2O5, while the use of WO3, Nb2O5 and MgO was not effective. The melting points of the former group were below 820 °C, while those of the latter group were higher than 1,000 °C. Among the former group, the selective sensing of ammonia was strongly dependent on the calcination temperature, which was optimum around melting point of the corresponding metal oxides. The good spreading of the metal oxides on the electrode is suggested to be one of the important factors. In the former group, the relative response of ammonia to propene was in the order of MoO3 > Bi2O3 > V2O5, which agreed well with the acidity of the metal oxides. The importance of the acidic properties of metal oxides for ammonia sensing was clarified.

  3. Thermo-oxidative ageing of an organo-modified clay and effects on the properties of PA6 based nanocomposites

    International Nuclear Information System (INIS)

    Scaffaro, R.; Botta, L.; Frache, A.; Bellucci, F.

    2013-01-01

    Highlights: ► The degradation of an organo-clay thermal treated under different atmospheres was investigated. ► The evolution of chemical composition was monitored by a combined TGA–FTIR analysis. ► The organic modifier in interlamellar spaces undergoes a rearrangement. ► PA6 based composites containing the thermal treated clay was prepared by melt mixing. ► The properties of composites worsened by increasing the treatment time of the clay. - Abstract: In this work a careful investigation on the degradation of an organically modified montmorillonite sample (Cloisite 15A) thermal treated under different atmospheres, namely nitrogen, air and oxygen enriched atmosphere was performed. The exposure time of the thermal treatment ranged between 5 and 300 min. The chemical composition evolution as function of the thermal treatment conditions of the clay organic modifier was monitored by means of combined thermogravimetry/Fourier transform infrared spectroscopy (TGA–FTIR). Moreover, the morphological behaviour of treated Cloisite 15A samples as function of the time and of the decomposition atmosphere was investigated by X-ray diffraction analysis (XRD). In order to understand the possible different interactions of neat and degraded modified clay with a polymeric matrix, PA6 based composites containing 5% of clay were prepared in the melt and fully characterized by a rheological, mechanical and morphological point of view. The results showed that during the thermal treatment the organic modifier in the interlamellar spaces undergoes a rearrangement, while the external unbound modifier degrades. At long exposure times, the degradation gradually extends to the clay galleries involving the internal modifier. These effects are more intense, as expected, when increasing oxygen concentration of the treatment atmosphere. As expected, the properties of the prepared nanocomposites were influenced by the degradation level of the incorporated clay. In particular, the

  4. An electrochemical ELISA-like immunosensor for miRNAs detection based on screen-printed gold electrodes modified with reduced graphene oxide and carbon nanotubes.

    Science.gov (United States)

    Tran, H V; Piro, B; Reisberg, S; Huy Nguyen, L; Dung Nguyen, T; Duc, H T; Pham, M C

    2014-12-15

    We design an electrochemical immunosensor for miRNA detection, based on screen-printed gold electrodes modified with reduced graphene oxide and carbon nanotubes. An original immunological approach is followed, using antibodies directed to DNA.RNA hybrids. An electrochemical ELISA-like amplification strategy was set up using a secondary antibody conjugated to horseradish peroxidase (HRP). Hydroquinone is oxidized into benzoquinone by the HRP/H2O2 catalytic system. In turn, benzoquinone is electroreduced into hydroquinone at the electrode. The catalytic reduction current is related to HRP amount immobilized on the surface, which itself is related to miRNA.DNA surface density on the electrode. This architecture, compared to classical optical detection, lowers the detection limit down to 10 fM. Two miRNAs were studied: miR-141 (a prostate biomarker) and miR-29b-1 (a lung cancer biomarker). Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Electrochemical Oxidation of Cysteine at a Film Gold Modified Carbon Fiber Microelectrode Its Application in a Flow—Through Voltammetric Sensor

    Science.gov (United States)

    Wang, Lai-Hao; Huang, Wen-Shiuan

    2012-01-01

    A flow-electrolytical cell containing a strand of micro Au modified carbon fiber electrodes (CFE) has been designedand characterized for use in a voltammatric detector for detecting cysteine using high-performance liquid chromatography. Cysteine is more efficiently electrochemical oxidized on a Au /CFE than a bare gold and carbon fiber electrode. The possible reaction mechanism of the oxidation process is described from the relations to scan rate, peak potentials and currents. For the pulse mode, and measurements with suitable experimental parameters, a linear concentration from 0.5 to 5.0 mg·L−1 was found. The limit of quantification for cysteine was below 60 ng·mL−1. PMID:22737024

  6. Effect of 3 modified fats and a conventional fat on appetite, energy intake, energy expenditure, and substrate oxidation in healthy men

    DEFF Research Database (Denmark)

    Bendixen, H.; Flint, A.; Raben, A.

    2002-01-01

    Background: Different dietary fats are metabolized differently in humans and may influence energy expenditure, substrate oxidation, appetite regulation, and body weight regulation.Objective: We examined the short-term effects of 4 triacylglycerols (test fats) on subjective appetite, ad libitum...... energy intake, meal-induced thermogenesis, and postprandial substrate oxidation.Design: Eleven healthy, normal-weight men (mean age: 25.1 +/-0.5 y) consumed 4 different test fats [conventional fat (rapeseed oil) and 3 modified fats (lipase-structured fat, chemically structured fat, and physically mixed...... fat)] in a randomized, double-blind, crossover design.Results: No significant differences in appetite sensations or ad libitum energy intakes were observed between the 4 test fats. Overall, the 4 fats exerted different effects on energy expenditure (meal effect: P...

  7. Cu-modified carbon spheres/reduced graphene oxide as a high sensitivity of gas sensor for NO2 detection at room temperature

    Science.gov (United States)

    Su, Zhibin; Tan, Li; Yang, Ruiqiang; Zhang, Yu; Tao, Jin; Zhang, Nan; Wen, Fusheng

    2018-03-01

    Nitrogen dioxide (NO2) as one of the most serious air pollution is harmful to people's health, therefore high-performance gas sensors is critically needed. Here, Cu-modified carbon spheres/reduced graphene oxide (Cu@CS/RGO) composite have been prepared as NO2 gas sensor material. Carbon sphere in the interlayer of RGO can increase the specific surface area of RGO. Copper nanoparticles decorated on the surface of CS can effectively enhance the adsorption activity of RGO as supplier of free electrons. The experimental results showed that its particular structure improved the gas sensitivity of RGO at different NO2 concentrations at room temperature.

  8. Effect of 3 modified fats and a conventional fat on appetite, energy intake, energy expenditure, and substrate oxidation in healthy men

    DEFF Research Database (Denmark)

    Bendixen, H.; Flint, A.; Raben, A.

    2002-01-01

    energy intake, meal-induced thermogenesis, and postprandial substrate oxidation.Design: Eleven healthy, normal-weight men (mean age: 25.1 +/-0.5 y) consumed 4 different test fats [conventional fat (rapeseed oil) and 3 modified fats (lipase-structured fat, chemically structured fat, and physically mixed...... fat)] in a randomized, double-blind, crossover design.Results: No significant differences in appetite sensations or ad libitum energy intakes were observed between the 4 test fats. Overall, the 4 fats exerted different effects on energy expenditure (meal effect: P...

  9. Effects of HCl and HNO3 on the oxidation of toluene to benzaldehyde by H2O2 over TS-1 modified with Al in aqueous phase

    Directory of Open Access Journals (Sweden)

    Paricha Pongjirawat

    2014-09-01

    Full Text Available This research studies effects of HCl and HNO3 in aqueous solution on the oxidation reaction between toluene and hydrogen peroxide to benzaldehyde over titanium silicalite-1 catalyst modified with Al. The reaction was carried out at reaction temperature 120°C in a pressurized autoclave reactor. The research found that the addition of HCl and HNO3 not only increases the concentration of toluene in the aqueous phase but also increases the formation of benzaldehyde as main product in the reaction.

  10. Manganese oxide nanoflakes/multi-walled carbon nanotubes/chitosan nanocomposite modified glassy carbon electrode as a novel electrochemical sensor for chromium (III) detection

    International Nuclear Information System (INIS)

    Salimi, Abdollah; Pourbahram, Bahareh; Mansouri-Majd, Samira; Hallaj, Rahman

    2015-01-01

    Highlights: • CNTs/chitosan/GC electrode used as platform for electrodeposition of MnO x -nanoflakes. • Modified electrode has excellent catalytic activity for oxidation of Cr 3+ at pH 3–7. • Detection limit and sensitivity of sensor for Cr 3+ detection were 0.3 μM and 18.7 nA/μM. • Sensor has good stability and high selectivity in the presence of common interferences. • Sensor applied for the detection of Cr 3+ in real samples with satisfactory results. - Abstract: In this research a nanocomposite containing chitosan (Chit) and maltiwalled carbon nanotubes (MWCNTs) was applied as platform for immobilization of electrodeposited manganese oxide (MnOx) nanostructures. First, glassy carbon (GC) electrode modified with thin film of Chitosan/MWCNTs nanocomposite. Then MnO x nanostructures was electrodeposited onto Chitosan/MWCNTs modified GC electrode using combination of constant potential step (0.6 V) and cyclic voltammetry(0.3–0.6 V) techniques. The XRD patterns and scanning electron microscope images indicated immobilization of uniformly MnOx nanoflakes with high crystallite onto MWCNTs/Chit film. The modified electrode shows a well-defined redox couple for Mn 2+ /MnO 2 system. Charge transfer coefficient (α), electron transfer rate constant (k s ) and surface concentration (Γ) were 0.394, 3.44 s −1 and 3.3 × 10 −11 mol cm −2 , respectively. The modified electrode showed excellent electrocatalytic activity toward oxidation of chromium (III) at natural pH solutions. Cyclic voltammetry and hydrodynamic amperometery were applied as measuring techniques for chromium detection. Detection limit, sensitivity and linear concentration range of the sensor were, 0.3 (μM), 18.7 nAμ M −1 and 3 μM to 200 μM, respectively. Moreover, the sensor retained about 90% of its original response toward Cr(III) after storage three months in ambient condition. Furthermore, the sensor response toward different common interferences was negligible. Finally, the

  11. Photoelectrocatalytic oxidation of glucose at a ruthenium complex modified titanium dioxide electrode promoted by uric acid and ascorbic acid for photoelectrochemical fuel cells

    Science.gov (United States)

    Lu, Shuo-Jian; Ji, Shi-Bo; Liu, Jun-Chen; Li, Hong; Li, Wei-Shan

    2015-01-01

    The simultaneous presence of uric acid (UA) and ascorbic acid (AA) is first found to largely promote the photoelectrocatalytic oxidation of glucose (GLU) at an indium-tin oxide (ITO) or TiO2 nanoparticles/ITO electrode modified with [Ru(tatp)3]2+ (tatp = 1,4,8,9-tetra-aza-triphenylene) possessing good redox activity and nanoparticle size distribution. A well-defined electrocatalytic peak for GLU oxidation is shown at 0.265 V (vs. SCE) under approximate physiological conditions upon incorporation of UA and AA. The [Ru(tatp)3]2+/ITO electrode exhibits attractive amperometric oxidation responses towards GLU, UA and AA, while controlled potentiostatically at 0.3 V, 0.7 V and 1.0 V, respectively, indicating high sensitivity and excellent reproducibility. On basis of the photoelectrocatalysis of [Ru(tatp)3]2+/TiO2/ITO anode, a GLU concentration-dependent photoelectrochemical fuel cell vs. SCE is elaborately assembled. The proposed free-enzyme photoelectrochemical fuel cell employing 0.1 M GLU associated with 0.01 M UA and 0.01 M AA as fuel shows open-circuit photovoltage of 0.608 V, short-circuit photocurrent density of 124.5 μA cm-2 and maximum power density of 21.75 μW cm-2 at 0.455 V, fill factor of 0.32 and photoenergy conversion efficiency of 36.65%, respectively.

  12. Rate and Selectivity Control in Thioether and Alkene Oxidation with H 2 O 2 over Phosphonate-Modified Niobium(V)-Silica Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Thornburg, Nicholas E.; Notestein, Justin M. (NWU)

    2017-09-05

    Supported metal oxide catalysts are versatile materials for liquid-phase oxidations, including alkene epoxidation and thioether sulfoxidation with H2O2. Periodic trends in H2O2 activation was recently demonstrated for alkene epoxidation, highlighting Nb-SiO2 as a more active and selective catalyst than Ti-SiO2. Three representative catalysts are studied consisting of NbV, TiIV, and ZrIV on silica, each made through a molecular precursor approach that yields highly dispersed oxide sites, for thioanisole oxidation by H2O2. Initial rates trend Nb>Ti>>Zr, as for epoxidation, and Nb outperforms Ti for a number of other thioethers. In contrast, selectivity to sulfoxide vs. sulfone trends Ti>Nb>>Zr at all conversions. Modifying the Nb-SiO2 catalyst with phenylphosphonic acid does not completely remove sulfoxidation reactivity, as it did for photooxidation and epoxidation, and results in an unusual material active for sulfoxidation but neither epoxidation nor overoxidation to the sulfone.

  13. Electrocatalytic Oxidation of Venlafaxine at a Multiwall Carbon Nanotubes-Ionic Liquid Gel Modified Glassy Carbon Electrode and Its Electrochemical Determination

    Directory of Open Access Journals (Sweden)

    Ling Ding

    2015-03-01

    Full Text Available The electrocatalytic oxidation of venlafaxine (VEN was investigated at a glassy carbon electrode (GCE, the modified electrode by a gel containing multiwall carbon nanotubes (MWCNTs and a room-temperature ionic liquid (RTIL, 1-butyl-3-methylimidazolium hexafluorophate (BMIMPF6 in 0.10 mol L−1 phosphate buffer solution (PBS, pH 6.8. It was found that an irreversible anodic oxidation peak of VEN with the peak potential (Epa as 0.780 V appeared at MWCNTs-RTIL/GCE. The electrode reaction process was a diffusion-controlled one and the electrochemical oxidation involved two electrons transferring and two protons participation. Furthermore, the charge-transfer coefficient (α, and the electrode reaction rate constant (kf of VEN were found to be 0.91 and 3.04×10−2 s−1, respectively. Under the optimized conditions, the electrocatalytic oxidation peak currents were linearly dependent on the concentration of VEN in the concentration range from 2.0×10−6 mol L−1 ~ 2.0×10−3 mol L−1 with the limit of detection (S / N = 3 as 1.69×10−6 mol L−1. The proposed method has been successfully applied in the electrochemical quantitative determination of VEN content in commercial venlafaxine hydrochloride capsules and the determination results could meet the requirement of the quantitative determination.

  14. Biobutanol as Fuel for Direct Alcohol Fuel Cells-Investigation of Sn-Modified Pt Catalyst for Butanol Electro-oxidation.

    Science.gov (United States)

    Puthiyapura, Vinod Kumar; Brett, Dan J L; Russell, Andrea E; Lin, Wen-Feng; Hardacre, Christopher

    2016-05-25

    Direct alcohol fuel cells (DAFCs) mostly use low molecular weight alcohols such as methanol and ethanol as fuels. However, short-chain alcohol molecules have a relative high membrane crossover rate in DAFCs and a low energy density. Long chain alcohols such as butanol have a higher energy density, as well as a lower membrane crossover rate compared to methanol and ethanol. Although a significant number of studies have been dedicated to low molecular weight alcohols in DAFCs, very few studies are available for longer chain alcohols such as butanol. A significant development in the production of biobutanol and its proposed application as an alternative fuel to gasoline in the past decade makes butanol an interesting candidate fuel for fuel cells. Different butanol isomers were compared in this study on various Pt and PtSn bimetallic catalysts for their electro-oxidation activities in acidic media. Clear distinctive behaviors were observed for each of the different butanol isomers using cyclic voltammetry (CV), indicating a difference in activity and the mechanism of oxidation. The voltammograms of both n-butanol and iso-butanol showed similar characteristic features, indicating a similar reaction mechanism, whereas 2-butanol showed completely different features; for example, it did not show any indication of poisoning. Ter-butanol was found to be inactive for oxidation on Pt. In situ FTIR and CV analysis showed that OHads was essential for the oxidation of primary butanol isomers which only forms at high potentials on Pt. In order to enhance the water oxidation and produce OHads at lower potentials, Pt was modified by the oxophilic metal Sn and the bimetallic PtSn was studied for the oxidation of butanol isomers. A significant enhancement in the oxidation of the 1° butanol isomers was observed on addition of Sn to the Pt, resulting in an oxidation peak at a potential ∼520 mV lower than that found on pure Pt. The higher activity of PtSn was attributed to the

  15. Electrochemical sensing of nitrite using a glassy carbon electrode modified with reduced functionalized graphene oxide decorated with flower-like zinc oxide

    International Nuclear Information System (INIS)

    Marlinda, Ab Rahman; Pandikumar, Alagarsamy; Yusoff, Norazriena; Huang, Nay Ming; Lim, Hong Ngee

    2015-01-01

    A nanocomposite consisting of flower-like zinc oxide (ZnO) and reduced functionalized graphene oxide (rFGO) was prepared via a hydrothermal route, and characterized by spectrophotometry, photoluminescence, Raman spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The nanocomposite was deposited on the surface of a glassy carbon electrode and studied using impedance spectroscopy. It exhibits excellent electrocatalytic activity toward the oxidation of nitrite. At a working potential of 0.9 V (vs. Ag/AgCl), it displayed a higher current and lower over potential (reduced by up to ∼200 mV) than controlled electrodes. This is attributed to the synergistic catalytic effects of the ZnO and rfGO. The oxidation current is linearly related to the concentration of nitrite in the 10 μM to 8 mM range, and the detection limit is 33 μM. Its excellent electrocatalytic activity, wide linear range, low detection limit, high sensitivity, and rapid response time make this nanocomposite-based electrode a potential candidate for practical applications. (author)

  16. Amperometric detection of hydrogen peroxide at nano-nickel oxide/thionine and celestine blue nanocomposite-modified glassy carbon electrodes

    International Nuclear Information System (INIS)

    Noorbakhsh, Abdollah; Salimi, Abdollah

    2009-01-01

    A simple procedure was developed to prepare a glassy carbon (GC) electrode modified with nickel oxide (NiOx) nanoparticles and water-soluble dyes. By immersing the GC/NiOx modified electrode into thionine (TH) or celestine blue (CB) solutions for a short period of time (5-120 s), a thin film of the proposed molecules was immobilized onto the electrode surface. The modified electrodes showed stable and a well-defined redox couples at a wide pH range (2-12), with surface confined characteristics. In comparison to usual methods for the immobilization of dye molecules, such as electropolymerization or adsorption on the surface of preanodized electrodes, the electrochemical reversibility and stability of these modified electrodes have been improved. The surface coverage and heterogeneous electron transfer rate constants (k s ) of thionin and celestin blue immobilized on a NiOx-GC electrode were approximately 3.5 x 10 -10 mol cm -2 , 6.12 s -1 , 5.9 x 10 -10 mol cm -2 and 6.58 s -1 , respectively. The results clearly show the high loading ability of the NiOx nanoparticles and great facilitation of the electron transfer between the immobilized TH, CB and NiOx nanoparticles. The modified electrodes show excellent electrocatalytic activity toward hydrogen peroxide reduction at a reduced overpotential. The catalytic rate constants for hydrogen peroxide reduction at GC/NiOx/CB and GC/NiOx/TH were 7.96 (±0.2) x 10 3 M -1 s -1 and 5.5 (±0.2) x 10 3 M -1 s -1 , respectively. The detection limit, sensitivity and linear concentration range for hydrogen peroxide detection were 1.67 μM, 4.14 nA μM -1 nA μM -1 and 5 μM to 20 mM, and 0.36 μM, 7.62 nA μM -1 , and 1 μM to 10 mM for the GC/NiOx/TH and GC/NiOx/CB modified electrodes, respectively. Compared to other modified electrodes, these modified electrodes have many advantages, such as remarkable catalytic activity, good reproducibility, simple preparation procedures and long-term stabilities of signal responses during

  17. Preparation and electrocatalytic oxidation properties of a nickel pentacyanonitrosylferrate modified carbon composite electrode by two-step sol-gel technique: improvement of the catalytic activity

    International Nuclear Information System (INIS)

    Salimi, Abdollah; Abdi, Kamaleddin; Khayatiyan, Gholam-Reza

    2004-01-01

    The sol-gel technique was used to construct nickel pentacyanonitrosylferrate (NiPCNF) modified composite ceramic carbon electrodes (CCEs). This involves two steps: forming a CCE containing Ni powder and then immersing the electrode into a sodium pentacyanonitrosyl-ferrate solution (electroless deposition). The cyclic voltammograms of the resulting surface modified CCE under optimum conditions show a well-defined redox couple due to the [Ni II Fe III/II (CN) 5 NO] 0/-1 system. The electrochemical properties and stability of the modified electrode were investigated by cyclic voltammetry. The apparent electron transfer rate constant (k s ) and transfer coefficient (α) were determined by cyclic voltammetry being about 1.1 s -1 and 0.55, respectively. Sulfite has been chosen as a model to elucidate the electrocatalytic ability of NiPCNF-modified CCE prepared by one- or two-step sol-gel technique. The modified electrode showed excellent electrocatalytic activity toward the SO 3 2- electro oxidation in pH range 3-9 in comparison with CCE modified by homogeneous mixture of graphite powder, Ni(NO 3 ) 2 and Na 2 [Fe(CN) 5 NO] (one-step sol-gel technique). Sulfite was determined amperometrically at the surface of this modified electrode in pH 7. Under the optimized conditions the calibration curve is linear in the concentration range 2 μM to 2.0 mM. The detection limit (signal-to-noise is 3) and sensitivity are 0.5 μM and 13.5 nA/μM. The modified carbon ceramic electrode containing nickel pentacyanonitrosylferrate shows good repeatability, short response time, t (90%) 2 [Fe(CN) 5 NO] solution. The advantages of the SO 3 2- amperometrically detector based on the nickel pentacyanonitrosylferrate-doped CCE is high sensitivity, inherent stability at wide pH range, excellent catalytic activity and less expense and simplicity of preparation. This sensor can be used as amperometric detector in chromatographic instruments

  18. Self-assembly surface modified indium-tin oxide anodes for single-layer light-emitting diodes

    CERN Document Server

    Morgado, J; Charas, A; Matos, M; Alcacer, L; Cacialli, F

    2003-01-01

    We study the effect of indium-tin oxide surface modification by self assembling of highly polar molecules on the performance of single-layer light-emitting diodes (LEDs) fabricated with polyfluorene blends and aluminium cathodes. We find that the efficiency and light-output of such LEDs is comparable to, and sometimes better than, the values obtained for LEDs incorporating a hole injection layer of poly(3,4-ethylene dioxythiophene) doped with polystyrene sulphonic acid. This effect is attributed to the dipole-induced work function modification of indium-tin oxide.

  19. Self-assembly surface modified indium-tin oxide anodes for single-layer light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Morgado, Jorge [Instituto de Telecomunicacoes and Departamento de Engenharia Quimica, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisbon (Portugal); Barbagallo, Nunzio [Instituto de Telecomunicacoes and Departamento de Engenharia Quimica, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisbon (Portugal); Charas, Ana [Instituto de Telecomunicacoes and Departamento de Engenharia Quimica, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisbon (Portugal); Matos, Manuel [Departamento de Engenharia Quimica, Instituto Superior de Engenharia de Lisboa, Rua Conselheiro Emidio Navarro-1, P-1949-001 Lisbon (Portugal); Alcacer, Luis [Instituto de Telecomunicacoes and Departamento de Engenharia Quimica, Instituto Superior Tecnico, Avenida Rovisco Pais, P-1049-001 Lisbon (Portugal); Cacialli, Franco [Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT (United Kingdom)

    2003-03-07

    We study the effect of indium-tin oxide surface modification by self assembling of highly polar molecules on the performance of single-layer light-emitting diodes (LEDs) fabricated with polyfluorene blends and aluminium cathodes. We find that the efficiency and light-output of such LEDs is comparable to, and sometimes better than, the values obtained for LEDs incorporating a hole injection layer of poly(3,4-ethylene dioxythiophene) doped with polystyrene sulphonic acid. This effect is attributed to the dipole-induced work function modification of indium-tin oxide.

  20. Pt nanoparticles modified by rare earth oxides: Electronic effect and influence to catalytic hydrogenation of 3-phenoxybenzaldehyde

    International Nuclear Information System (INIS)

    Mou, Zhigang; Han, Ming; Li, Gang; Du, Yukou; Yang, Ping; Zhang, Hailu; Deng, Zongwu

    2013-01-01

    Graphical abstract: - Highlights: • The rare earths modified Pt/Al 2 O 3 were prepared by colloidal deposition method. • Modification of Pt by the rare earth enhanced catalytic hydrogenation activity. • The activity improvement is due to electron interaction between Pt and rare earth. • The hydrogenation mechanism of rare earth modified Pt catalyst was proposed. - Abstract: The rare earth elements (La, Ce, Nd, Sm, Pr, and Gd) modified Pt/Al 2 O 3 catalysts were prepared by the colloidal deposition and chemical reduction methods, respectively. Pt nanoparticles with average size 3 ± 0.5 nm were uniformly dispersed on the surface of Al 2 O 3 for the samples prepared by the colloidal deposition method, which exhibited higher activities in the hydrogenation of 3-phenoxybenzadehyde than the corresponding samples prepared by chemical reduction method. Moreover, except Gd, the catalysts modified by rare earth elements showed better catalytic performance than unmodified Pt/Al 2 O 3 . For Pt–Ce/Al 2 O 3 catalyst, when the weight percent of Pt and Ce was 0.5 and 0.25, respectively, the hydrogenation conversion of 3-phenoxybenzaldehyde was 97.3% after 6 h reaction. This activity improvement is due to the electronic interaction between Pt and rare earth elements, which was investigated by X-ray photoelectron spectroscopy

  1. Pt nanoparticles modified by rare earth oxides: Electronic effect and influence to catalytic hydrogenation of 3-phenoxybenzaldehyde

    Energy Technology Data Exchange (ETDEWEB)

    Mou, Zhigang; Han, Ming; Li, Gang; Du, Yukou [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Yang, Ping, E-mail: pyang@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Zhang, Hailu [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China); Deng, Zongwu, E-mail: zwdeng2007@sinano.ac.cn [Suzhou Institute of Nano-tech and Nano-bionics, Chinese Academy of Sciences, Suzhou 215123 (China)

    2013-11-15

    Graphical abstract: - Highlights: • The rare earths modified Pt/Al{sub 2}O{sub 3} were prepared by colloidal deposition method. • Modification of Pt by the rare earth enhanced catalytic hydrogenation activity. • The activity improvement is due to electron interaction between Pt and rare earth. • The hydrogenation mechanism of rare earth modified Pt catalyst was proposed. - Abstract: The rare earth elements (La, Ce, Nd, Sm, Pr, and Gd) modified Pt/Al{sub 2}O{sub 3} catalysts were prepared by the colloidal deposition and chemical reduction methods, respectively. Pt nanoparticles with average size 3 ± 0.5 nm were uniformly dispersed on the surface of Al{sub 2}O{sub 3} for the samples prepared by the colloidal deposition method, which exhibited higher activities in the hydrogenation of 3-phenoxybenzadehyde than the corresponding samples prepared by chemical reduction method. Moreover, except Gd, the catalysts modified by rare earth elements showed better catalytic performance than unmodified Pt/Al{sub 2}O{sub 3}. For Pt–Ce/Al{sub 2}O{sub 3} catalyst, when the weight percent of Pt and Ce was 0.5 and 0.25, respectively, the hydrogenation conversion of 3-phenoxybenzaldehyde was 97.3% after 6 h reaction. This activity improvement is due to the electronic interaction between Pt and rare earth elements, which was investigated by X-ray photoelectron spectroscopy.

  2. Photocatalytic Activity and Characterization of Carbon-Modified Titania for Visible-Light-Active Photodegradation of Nitrogen Oxides

    Directory of Open Access Journals (Sweden)

    Chun-Hung Huang

    2012-01-01

    Full Text Available A variety of carbon-modified titania powders were prepared by impregnation method using a commercial available titania powder, Hombikat UV100, as matrix material while a range of alcohols from propanol to hexanol were used as precursors of carbon sources. Rising the carbon number of alcoholic precursor molecule, the modified titania showed increasing visible activities of NOx photodegradation. The catalyst modified with cyclohexanol exhibited the best activities of 62%, 62%, 59%, and 54% for the total NOx removal under UV, blue, green, and red light irradiation, respectively. The high activity with long wavelength irradiation suggested a good capability of photocatalysis in full visible light spectrum. Analysis of UV-visible spectrum indicated that carbon modification promoted visible light absorption and red shift in band gap. XPS spectroscopic analysis identified the existence of carbonate species (C=O, which increased with the increasing carbon number of precursor molecule. Photoluminescence spectra demonstrated that the carbonate species suppressed the recombination rate of electron-hole pair. As a result, a mechanism of visible-light-active photocatalyst was proposed according to the formation of carbonate species on carbon-modified TiO2.

  3. Dietary antioxidant and anti-inflammatory intake modifies the effect of cadmium exposure on markers of systemic inflammation and oxidative stress

    Energy Technology Data Exchange (ETDEWEB)

    Colacino, Justin A.; Arthur, Anna E.; Ferguson, Kelly K.; Rozek, Laura S., E-mail: rozekl@umich.edu

    2014-05-01

    Chronic cadmium exposure may cause disease through induction of systemic oxidative stress and inflammation. Factors that mitigate cadmium toxicity and could serve as interventions in exposed populations have not been well characterized. We used data from the 2003–2010 National Health and Nutrition Examination Survey to quantify diet's role in modifying associations between cadmium exposure and oxidative stress and inflammation. We created a composite antioxidant and anti-inflammatory diet score (ADS) by ranking participants by quintile of intake across a panel of 19 nutrients. We identified associations and effect modification between ADS, urinary cadmium, and markers of oxidative stress and inflammation by multiple linear regression. An interquartile range increase in urinary cadmium was associated with a 47.5%, 8.8%, and 3.7% increase in C-reactive protein (CRP), gamma glutamyl transferase (GGT), and alkaline phosphatase (ALP), respectively. An interquartile range increase in ADS was associated with an 7.4%, 3.3%, 5.2%, and 2.5% decrease in CRP, GGT, ALP, and total white blood cell count respectively, and a 3.0% increase in serum bilirubin. ADS significantly attenuated the association between cadmium exposure, CRP and ALP. Dietary interventions may provide a route to reduce the impact of cadmium toxicity on the population level. - Highlights: • Cadmium may cause chronic disease through oxidative stress or inflammation. • We developed a score to quantify dietary antioxidant and anti-inflammatory intake. • Cadmium was associated with markers of oxidative stress and inflammation. • Antioxidant and anti-inflammatory intake mitigated the effects of cadmium exposure. • Dietary interventions may be effective against chronic cadmium toxicity.

  4. Dietary antioxidant and anti-inflammatory intake modifies the effect of cadmium exposure on markers of systemic inflammation and oxidative stress

    International Nuclear Information System (INIS)

    Colacino, Justin A.; Arthur, Anna E.; Ferguson, Kelly K.; Rozek, Laura S.

    2014-01-01

    Chronic cadmium exposure may cause disease through induction of systemic oxidative stress and inflammation. Factors that mitigate cadmium toxicity and could serve as interventions in exposed populations have not been well characterized. We used data from the 2003–2010 National Health and Nutrition Examination Survey to quantify diet's role in modifying associations between cadmium exposure and oxidative stress and inflammation. We created a composite antioxidant and anti-inflammatory diet score (ADS) by ranking participants by quintile of intake across a panel of 19 nutrients. We identified associations and effect modification between ADS, urinary cadmium, and markers of oxidative stress and inflammation by multiple linear regression. An interquartile range increase in urinary cadmium was associated with a 47.5%, 8.8%, and 3.7% increase in C-reactive protein (CRP), gamma glutamyl transferase (GGT), and alkaline phosphatase (ALP), respectively. An interquartile range increase in ADS was associated with an 7.4%, 3.3%, 5.2%, and 2.5% decrease in CRP, GGT, ALP, and total white blood cell count respectively, and a 3.0% increase in serum bilirubin. ADS significantly attenuated the association between cadmium exposure, CRP and ALP. Dietary interventions may provide a route to reduce the impact of cadmium toxicity on the population level. - Highlights: • Cadmium may cause chronic disease through oxidative stress or inflammation. • We developed a score to quantify dietary antioxidant and anti-inflammatory intake. • Cadmium was associated with markers of oxidative stress and inflammation. • Antioxidant and anti-inflammatory intake mitigated the effects of cadmium exposure. • Dietary interventions may be effective against chronic cadmium toxicity

  5. Two-dimensional zeolites: Adsorption of carbon dioxide on pristine materials and on materials modified by magnesium oxide

    Czech Academy of Sciences Publication Activity Database

    Zukal, Arnošt; Kubů, Martin; Pastva, Jakub

    2017-01-01

    Roč. 21, OCT 2017 (2017), s. 9-16 ISSN 2212-9820 R&D Projects: GA ČR(CZ) GAP106/12/0189 Institutional support: RVO:61388955 Keywords : Carbon dioxide adsorption * Two-dimensional zeolites * Magnesium oxide incorporation Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.292, year: 2016

  6. Genetic polymorphisms in DNA repair and oxidative stress pathways may modify the association between body size and postmenopausal breast cancer

    Czech Academy of Sciences Publication Activity Database

    McCullough, L. E.; Eng, S. M.; Bradshaw, P. T.; Cleveland, R. J.; Steck, S. E.; Terry, M. B.; Shen, J.; Crew, K.D.; Rössner ml., Pavel; Ahn, J.; Ambrosone, Ch.B.; Teitelbaum, S. L.; Neugut, A. I.; Santella, R. M.; Gammon, M. D.

    2015-01-01

    Roč. 25, č. 4 (2015), s. 263-269 ISSN 1047-2797 Institutional support: RVO:68378041 Keywords : breast cancer * body mass index * oxidative stress * DNA repair * Epidemiology Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.335, year: 2015

  7. Magnetic targeting of surface-modified superparamagnetic iron oxide nanoparticles yields antibacterial efficacy against biofilms of gentamicin-resistant staphylococci

    NARCIS (Netherlands)

    Subbiandoss, Guruprakash; Sharifi, Shahriar; Grijpma, Dirk W.; Laurent, Sophie; van der Mei, Henny C.; Mahmoudi, Morteza; Busscher, Henk J.

    Biofilms on biomaterial implants are hard to eradicate with antibiotics due to the protection offered by the biofilm mode of growth, especially when caused by antibiotic-resistant strains. Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used in various biomedical applications, such as

  8. Magnetic targeting of surface-modified superparamagnetic iron oxide nanoparticles yields antibacterial efficacy against biofilms of gentamicin-resistant staphylococci

    NARCIS (Netherlands)

    Subbiahdoss, G.; Sharifi, Shahriar; Grijpma, Dirk W.; Laurent, S.; van der Mei, H.C.; Mahmoudi, M.; Busscher, H.J.

    2012-01-01

    Biofilms on biomaterial implants are hard to eradicate with antibiotics due to the protection offered by the biofilm mode of growth, especially when caused by antibiotic-resistant strains. Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used in various biomedical applications, such as

  9. Is the titer of adipokinetic peptides in Leptinotarsa decemlineata fed on genetically modified potatoes increased by oxidative stress?

    Czech Academy of Sciences Publication Activity Database

    Kodrík, Dalibor; Krishnan, Natraj; Habuštová, Oxana

    2007-01-01

    Roč. 28, č. 5, (2007), s. 974-980 ISSN 0196-9781 R&D Projects: GA ČR GA522/05/0151; GA ČR(CZ) GA522/06/1591 Institutional research plan: CEZ:AV0Z50070508 Keywords : adipokinetic hormone * oxidative stress * GMO Subject RIV: ED - Physiology Impact factor: 2.368, year: 2007

  10. Highly effective permeability and antifouling performances of polypropylene non-woven fabric membranes modified with graphene oxide by inkjet printing and immersion coating methods.

    Science.gov (United States)

    Zhao, Chuan-Qi; Xu, Xiao-Chen; Li, Rui-Yun; Chen, Jie; Yang, Feng-Lin

    2013-01-01

    In the current study, graphene oxide (GO)-modified polypropylene non-woven fabric (PP-NWF) membranes were prepared via inkjet printing and immersion coating methods. Scanning electron microscopy, Fourier transform infrared spectroscopy, contact angle measurements, pure water permeation (JPWP) and protein adsorption were tested to evaluate the impact of the GO nanosheet on the characteristics and performance of modified PP-NWF membranes. The results showed that the exfoliated GO nanosheets uniformly deposited on the membrane surface and firmly embedded into the interlaced fibers, resulting in the improvement of membrane hydrophilicity, permeability and antifouling properties comparing with original PP-NWF membranes. The GO-printed and GO-coated membranes had 113 and 188% higher fluxes, and 70.95 and 75.74% lower protein adsorptions than the original PP-NWF membranes, respectively. After cross-linked treatment, ultrasound processing was conducted to evaluate the stability of the modified PP-NWF membranes. The results demonstrated that there was almost no decrease in permeation after ultrasonic treatment indicating that the cross-linking treatment could enhance the immobilization of the GO nanosheets on and into the modified membranes.

  11. Radio-immunoconjugated, Dox-loaded, surface-modified superparamagnetic iron oxide nanoparticles (SPIONs) as a bioprobe for breast cancer tumor theranostics

    International Nuclear Information System (INIS)

    Hamidreza Zolata; Hossein Afarideh; Fereydoun Abbasi-Davani

    2014-01-01

    In this research, we develop dual modality molecular imaging and also radio-immunotherapy (RIT) bioprobes, in the form of modified superparamagnetic iron oxide nanoparticles (SPIONs) conjugated to radiolabeled antibodies, for PET and MRI of HER2 expressing cancers as well as a PH sensitive drug carrier by embedded an anticancer agent for cancer therapeutic applications. The bioprobes were developed by conjugating 64 Cu labeled trastuzumab (herceptin) and rituximab (Anti CD-20) antibodies to modified SPIONs. The SPIONs were modified with carboxymethyl chitosan and functionalized with acrylic acid (AA). Also, with the purpose of identifying more effective bifunctional chelator (BFC), we compared the properties of novel BFC, p-NO 2 -Bn-PCTA with the commonly used DOTA-NHS for radio-immunoconjugate preparations. Moreover, a chemotherapy drug, doxorubicin, was then loaded onto engineered nanoparticles for targeted intracellular drug delivery and selective cancer cell killing. Resulting radio-immunoconjugated-SPIONs were evaluated for molecular imaging and effective targeting of the HER2+ receptors in SKBR3 cell lines and breast tumor bearing Balb/C mice. Therefore, our biocompatible SPIONs could serve as a promising multifunctional theranostics nanoplatform in dual modality imaging guided RIT of HER2 overexpressing cancer applicable to drug delivery and controlled drug release for trigger both intrinsic and extrinsic pathways of apoptosis. (author)

  12. Horseradish peroxidase-labeled silver/reduced graphene oxide thin film-modified screen-printed electrode for detection of carcinoembryonic antigen.

    Science.gov (United States)

    Lee, S X; Lim, H N; Ibrahim, I; Jamil, A; Pandikumar, A; Huang, N M

    2017-03-15

    In this study, a disposable and simple electrochemical immunosensor was fabricated for the detection of carcinoembryonic antigen. In this method, silver nanoparticles (AgNPs) were mixed with reduced graphene oxide (rGO) to modify the surface of screen-printed carbon electrode (SPE). Initially, AgNPs-rGO modified-SPEs were fabricated by using simple electrochemical deposition method. Then the carcinoembryonic antigen (CEA) was immobilized between the primary antibody and horseradish peroxidase (HRP)-conjugated secondary antibody onto AgNPs-rGO modified-SPEs to fabricate a sandwich-type electrochemical immunosensor. The proposed method could detect the CEA with a linear range of 0.05-0.50µgmL -1 and a detection limit down to 0.035µgmL -1 as compared to its non-sandwich counterpart, which yielded a linear range of 0.05-0.40µgmL -1 , with a detection limit of 0.042µgmL -1 . The immunosensor showed good performance in the detection of carcinoembryonic antigen, exhibiting a simple, rapid and low-cost. The immunosensor showed a higher sensitivity than an enzymeless sensor. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Investigation of oxygen reduction and methanol oxidation reaction activity of PtAu nano-alloy on surface modified porous hybrid nanocarbon supports

    Science.gov (United States)

    Parambath Vinayan, Bhaghavathi; Nagar, Rupali; Ramaprabhu, Sundara

    2016-09-01

    We investigate the electrocatalytic activity of PtAu alloy nanoparticles supported on various chemically modified carbon morphologies towards oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). The surface-modification of graphene nanosheets (f-G), multi-walled carbon nanotubes (f-MWNTs) and (graphene nanosheets-carbon nanotubes) hybrid support (f-G-MWNTs) were carried out by soft functionalization method using a cationic polyelectrolyte poly-(diallyldimethyl ammonium chloride). The Pt and PtAu alloy nanoparticles were dispersed over chemically modified carbon supports by sodium-borohydride assisted modified polyol reduction method. The electrochemical performance of all electrocatalysts were studied by half- and full-cell proton exchange membrane fuel cell (PEMFC) measurements and PtAu/f-G-MWNTs catalyst comparatively yielded the best catalytic performance. PEMFC full cell measurements of PtAu/f-G-MWNTs cathode electrocatalyst yield a maximum power density of 319 mW cm-2 at 60 °C without any back pressure,which is 2.1 times higher than that of cathode electrocatalyst Pt on graphene support. The high ORR and MOR activity of PtAu/f-G-MWNTs electrocatalyst is due to the alloying effect and inherent beneficial properties of porous hybrid nanocarbon support.

  14. Physicochemical properties and in vitro cytotoxicity of iron oxide-based nanoparticles modified with antiangiogenic and antitumor peptide A7R

    Energy Technology Data Exchange (ETDEWEB)

    Niescioruk, Anna; Nieciecka, Dorota; Puszko, Anna K.; Królikowska, Agata [University of Warsaw, Faculty of Chemistry (Poland); Kosson, Piotr [Polish Academy of Sciences, Department of Neuropeptides, Mossakowski Medical Research Centre (Poland); Perret, Gerard Y. [Université Paris 13, Sorbonne Paris Cité (France); Krysinski, Pawel; Misicka, Aleksandra, E-mail: misicka@chem.uw.edu.pl [University of Warsaw, Faculty of Chemistry (Poland)

    2017-05-15

    Superparamagnetic iron oxide-based nanoparticles (SPIONs) are promising carriers as targeted drug delivery vehicles, because they can be guided to their target with the help of an external magnetic field. Functionalization of nanoparticles’ surface with molecules, which bind with high affinity to receptors on target tissue significantly facilitates delivery of coated nanoparticles to their targeted site. Here, we demonstrate conjugation of an antiangiogenic and antitumor peptide ATWLPPR (A7R) to SPIONs modified with sebacic acid (SPIONs-SA). Successful conjugation was confirmed by various analytical techniques (FTIR, SERS, SEM-EDS, TEM, TGA). Cell cytotoxicity studies, against two cell lines (HUVEC and MDA-MB-231) indicated that SPIONs modified with A7R reduced HUVEC cell viability at concentrations higher than 0.01 mg Fe/mL, in comparison to cells that were exposed to either the nanoparticles modified with sebacic acid or A7R peptide solely, what might be partially caused by a process of internalization.

  15. Synthesis and Characterization of Graphene Oxide-Modified Bi2WO6 and Its Use as Photocatalyst

    Directory of Open Access Journals (Sweden)

    Xiaoyue Hu

    2016-01-01

    Full Text Available A Bi2WO6 photocatalyst modified with graphene was synthesized in a two-step template-free hydrothermal process. The prepared samples were characterized to explore their properties. The photocatalytic activities of the prepared samples were investigated by degrading dye model, Rhodamine B (RhB, under visible light irradiation. This showed that the modified Bi2WO6 photocatalyst with 1.2 wt% of graphene greatly improved photocatalytic activity during the degradation of dye pollutants, compared to pure Bi2WO6. The enhancement can be interpreted as the integrated effects of ultrahigh charge carriers’ mobility and high adsorption of RhB on graphene. Additionally, effects including catalysts dosage amount, pH of RhB solution, and temperature of reactor on the photocatalytically degrading RhB were also studied and discussed.

  16. High Temperature Oxidation Behavior of gamma-Ni+gamma'-Ni3Al Alloys and Coatings Modified with Pt and Reactive Elements

    Energy Technology Data Exchange (ETDEWEB)

    Mu, Nan [Iowa State Univ., Ames, IA (United States)

    2007-12-01

    Materials for high-pressure turbine blades must be able to operate in the high-temperature gases (above 1000 C) emerging from the combustion chamber. Accordingly, the development of nickel-based superalloys has been constantly motivated by the need to have improved engine efficiency, reliability and service lifetime under the harsh conditions imposed by the turbine environment. However, the melting point of nickel (1455 C) provides a natural ceiling for the temperature capability of nickel-based superalloys. Thus, surface-engineered turbine components with modified diffusion coatings and overlay coatings are used. Theses coatings are capable of forming a compact and adherent oxide scale, which greatly impedes the further transport of reactants between the high-temperature gases and the underlying metal and thus reducing attack by the atmosphere. Typically, these coatings contain β-NiAl as a principal constituent phase in order to have sufficient aluminum content to form an Al2O3 scale at elevated temperatures. The drawbacks to the currently-used {beta}-based coatings, such as phase instabilities, associated stresses induced by such phase instabilities, and extensive coating/substrate interdiffusion, are major motivations in this study to seek next-generation coatings. The high-temperature oxidation resistance of novel Pt + Hf-modified γ-Ni + γ-Ni3Al-based alloys and coatings were investigated in this study. Both early-stage and 4-days isothermal oxidation behavior of single-phase γ-Ni and γ'-Ni3Al alloys were assessed by examining the weight changes, oxide-scale structures, and elemental concentration profiles through the scales and subsurface alloy regions. It was found that Pt promotes Al2O3 formation by suppressing the NiO growth on both γ-Ni and γ'Ni3Al single-phase alloys. This effect increases with increasing Pt content. Moreover, Pt exhibits this effect even at

  17. Pure and Modified Co-Poly(amide-12-b-ethylene oxide) Membranes for Gas Separation Studied by Molecular Investigations.

    Science.gov (United States)

    De Lorenzo, Luana; Tocci, Elena; Gugliuzza, Annarosa; Drioli, Enrico

    2012-06-28

    This paper deals with a theoretical investigation of gas transport properties in a pure and modified PEBAX block copolymer membrane with N-ethyl-o/p-toluene sulfonamide (KET) as additive molecules. Molecular dynamics simulations using COMPASS force field, Gusev-Suter Transition State Theory (TST) and Monte Carlo methods were used. Bulk models of PEBAX and PEBAX/KET in different copolymer/additive compositions were assembled and analyzed to evaluate gas permeability and morphology to characterize structure-performance relationships.

  18. Dietary antioxidant and anti-inflammatory intake modifies the effect of cadmium exposure on markers of systemic inflammation and oxidative stress

    Science.gov (United States)

    Colacino, Justin A.; Arthur, Anna E.; Ferguson, Kelly K.; Rozek, Laura S.

    2014-01-01

    Chronic cadmium exposure may cause disease through induction of systemic oxidative stress and inflammation. Factors that mitigate cadmium toxicity and could serve as interventions in exposed populations have not been well characterized. We used data from the 2003–2010 National Health and Nutrition Examination Survey to quantify diet’s role in modifying associations between cadmium exposure and oxidative stress and inflammation. We created a composite antioxidant and anti-inflammatory diet score (ADS) by ranking participants by quintile of intake across a panel of 19 nutrients. We identified associations and effect modification between ADS, urinary cadmium, and markers of oxidative stress and inflammation by multiple linear regression. An interquartile range increase in urinary cadmium was associated with a 47.5%, 8.8%, and 3.7% increase in C-reactive protein (CRP), gamma glutamyl transferase (GGT), and alkaline phosphatase (ALP), respectively. An interquartile range increase in ADS was associated with an 7.4%, 3.3%, 5.2%, and 2.5% decrease in CRP, GGT, ALP, and total white blood cell count respectively, and a 3.0% increase in serum bilirubin. ADS significantly attenuated the association between cadmium exposure, CRP and ALP. Dietary interventions may provide a route to reduce the impact of cadmium toxicity on the population level. PMID:24607659

  19. Effects of antioxidant mixtures in the diet of finishing pigs on the oxidative status and shelf life of longissimus dorsi muscle packaged under modified atmosphere.

    Science.gov (United States)

    Rossi, R; Stella, S; Ratti, S; Maghin, F; Tirloni, E; Corino, C

    2017-11-01

    The effect of pig dietary supplementation with an antioxidant mixture (AOX), containing vitamin E and verbascoside, on animal oxidative status, meat quality parameters, and shelf life of the longissimus dorsi (LD) muscle was examined. Seventy pigs with an average live weight of 95.2 ± 1.2 kg were selected and assigned to 2 dietary treatments. The control (CTR) group was fed a commercial diet, and the AOX group was fed the same diet supplemented with the AOX, containing vitamin E and verbascoside from Verbenaceae extract, for 45 d before slaughter. At the beginning and at the end of the trial, blood samples were collected to determine oxidative status, using the Kit Radicaux Libres test. At slaughter, carcass weight was recorded and LD muscles from 10 pigs per treatment were sampled. Physical, chemical, microbiological, and sensory parameters and oxidative stability of LD muscle were assessed for up to 21 d of storage at 4°C under modified atmosphere packaging. Dietary AOX positively affected ( meat from the AOX group was comparable ( meat in appearance and aroma. A lower ( parameters were affected by dietary treatment. Overall, the present data showed that dietary AOX supplementation in pigs improved in vivo antioxidant status and exerted antioxidant and antimicrobial effects, thus enhancing the shelf life of raw pork under commercial conditions.

  20. Poly-L-lysine-modified reduced graphene oxide stabilizes the copper nanoparticles with higher water-solubility and long-term additively antibacterial activity.

    Science.gov (United States)

    Ouyang, Yu; Cai, Xiang; Shi, QingShan; Liu, Lili; Wan, Dongliang; Tan, Shaozao; Ouyang, Yousheng

    2013-07-01

    In order to improve the water-solubility and long-term antibacterial activity of copper nanoparticles (CuNPs), a poly-L-lysine-modified reduced graphene oxide (PLL-rGO) was used as the carrier of CuNPs, and a poly-L-lysine/reduced graphene oxide/copper nanoparticles (PLL-rGO-CuNPs) hybrid was prepared by anchoring the CuNPs on the reduced graphene oxide surface. The novel PLL-rGO-CuNPs hybrid was characterized and the antibacterial activity of it on gram-negative Escherichia coli and Gram-positive Staphylococcus aureus was tested. Such a hybrid showed additively antibacterial activity, and the CuNPs on PLL-rGO were more stable than those on polyvinyl pyrrolidone, resulting in long-term additively antibacterial effect. Meanwhile, this hybrid showed excellent water-solubility, suggesting great potential application in microbial control. Crown Copyright © 2013. Published by Elsevier B.V. All rights reserved.

  1. Iron oxide inside SBA-15 modified with amino groups as reusable adsorbent for highly efficient removal of glyphosate from water

    Science.gov (United States)

    Fiorilli, Sonia; Rivoira, Luca; Calì, Giada; Appendini, Marta; Bruzzoniti, Maria Concetta; Coïsson, Marco; Onida, Barbara

    2017-07-01

    Iron oxide clusters were incorporated into amino-functionalized SBA-15 in order to obtain a magnetically recoverable adsorbent. The physical-chemical properties of the material were characterized by FE-SEM, STEM, XRD, TGA, XPS, FT-IR and acid-base titration analysis. Iron oxide nanoparticles were uniformly dispersed into the pore of mesoporous silica and that the adsorbent is characterized high specific surface area (177 m2/g) and accessible porosity. The sorbent was successfully tested for the removal of glyphosate in real water matrices. Despite the significant content of inorganic ions, a quantitative removal of the contaminant was found. The complete regeneration of the sorbent after the adsorption process through diluted NaOH solution was also proved.

  2. Kinetics of the oxidative hydroxylation of sodium hypophosphite in the presence of copper (II chloride modified by humic (fulvo- acid

    Directory of Open Access Journals (Sweden)

    Zhaksyntay Kairbekov

    2012-12-01

    Full Text Available It was established that in soft conditions (50-70oC, PO2 = 1 atm sodium hypophosphite effectively is oxidized by oxygen in water solutions of copper(II chloride  to give mainly a phosphorous acid. Humic (fulvo- acid was extracted from brown coal of domestic deposit Kiyakty. For determination of optimum parameters of fulvo-acid extraction the laboratory experiments were carried out using the method of experiment planning. The kinetics, the intermediate and final products, optimal conditions of new catalytic reaction of NaH2PO2 oxidation by oxygen in water solution were defined by kinetics, volumometry, redox-potentiometry and a titration.

  3. High glucose modifies transient receptor potential canonical type 6 channels via increased oxidative stress and syndecan-4 in human podocytes

    DEFF Research Database (Denmark)

    Thilo, Florian; Lee, Marlene; Xia, Shengqiang

    2014-01-01

    oxidative stress and syndecan-4 (SDC-4) in human podocytes. Human podocytes were exposed to control conditions (5.6 mmol/L D-glucose), high glucose (30 mmol/L D-glucose or L-glucose), 100 μmol/L peroxynitrite, or high glucose and the superoxide dismutase mimetic tempol (100 μmol/L). TRPC6 and SDC-4.......44±0.07 (ptempol. Increased oxidative stress using peroxynitrite significantly increased TRPC6 transcripts to 4.29±1.26 (p....05) without altering SDC-4 transcripts or protein expression. In human podocytes transfected with scrambled siRNA, high D-glucose increased ROS after 90 min to 3.55±0.08 arbitrary units while 5.6 mmol/L D-glucose increased ROS to 2.49±0.09 (ptempol and by SDC...

  4. Beta-carotene reduces oxidative stress, improves glutathione metabolism and modifies antioxidant defense systems in lead-exposed workers

    Energy Technology Data Exchange (ETDEWEB)

    Kasperczyk, Sławomir, E-mail: kaslav@mp.pl [Dept. of Biochemistry, School of Medicine with the Division of Dentistry, Medical University of Silesia, ul. Jordana 19, 41-808 Zabrze (Poland); Dobrakowski, Michał [Dept. of Biochemistry, School of Medicine with the Division of Dentistry, Medical University of Silesia, ul. Jordana 19, 41-808 Zabrze (Poland); Kasperczyk, Janusz [Dept. of Environmental Medicine and Epidemiology, School of Medicine with the Division of Dentistry, Medical University of Silesia, ul. Jordana 19, 41-808 Zabrze (Poland); Ostałowska, Alina; Zalejska-Fiolka, Jolanta; Birkner, Ewa [Dept. of Biochemistry, School of Medicine with the Division of Dentistry, Medical University of Silesia, ul. Jordana 19, 41-808 Zabrze (Poland)

    2014-10-01

    The aim of this study was to determine whether beta-carotene administration reduces oxidative stress and influences antioxidant, mainly glutathione-related, defense systems in workers chronically exposed to lead. The population consisted of two randomly divided groups of healthy male volunteers exposed to lead. Workers in the first group (reference group) were not administered any antioxidants, while workers in the second group (CAR group) were treated orally with 10 mg of beta-carotene once a day for 12 weeks. Biochemical analysis included measuring markers of lead-exposure and oxidative stress in addition to the levels and activities of selected antioxidants. After treatment, levels of malondialdehyde, lipid hydroperoxides and lipofuscin significantly decreased compared with the reference group. However, the level of glutathione significantly increased compared with the baseline. Treatment with beta-carotene also resulted in significantly decreased glutathione peroxidase activity compared with the reference group, while the activities of other glutathione-related enzymes and of superoxide dismutase were not significantly changed. However, the activities of glucose-6-phosphate dehydrogenase and catalase, as well as the level of alpha-tocopherol, were significantly higher after treatment compared with the baseline. Despite controversy over the antioxidant properties of beta-carotene in vivo, our findings showed reduced oxidative stress after beta-carotene supplementation in chronic lead poisoning. - Highlights: • Beta-carotene reduces oxidative stress in lead-exposed workers. • Beta-carotene elevates glutathione level in lead-exposed workers. • Beta-carotene administration could be beneficial in lead poisoning.

  5. Pummelo Protects Doxorubicin-Induced Cardiac Cell Death by Reducing Oxidative Stress, Modifying Glutathione Transferase Expression, and Preventing Cellular Senescence

    Directory of Open Access Journals (Sweden)

    L. Chularojmontri

    2013-01-01

    Full Text Available Citrus flavonoids have been shown to reduce cardiovascular disease (CVD risks prominently due to their antioxidant effects. Here we investigated the protective effect of pummelo (Citrus maxima, CM fruit juice in rat cardiac H9c2 cells against doxorubicin (DOX- induced cytotoxicity. Four antioxidant compositions (ascorbic acid, hesperidin, naringin, and gallic acid were determined by HPLC. CM significantly increased cardiac cell survival from DOX toxicity as evaluated by MTT assay. Reduction of cellular oxidative stress was monitored by the formation of DCF fluorescent product and total glutathione (GSH levels. The changes in glutathione-S-transferase (GST activity and expression were determined by enzyme activity assay and Western blot analysis, respectively. Influence of CM on senescence-associated β-galactosidase activity (SA-β-gal was also determined. The mechanisms of cytoprotection involved reduction of intracellular oxidative stress, maintaining GSH availability, and enhanced GST enzyme activity and expression. DOX-induced cellular senescence was also attenuated by long-term CM treatment. Thus, CM fruit juice can be promoted as functional fruit to protect cells from oxidative cell death, enhance the phase II GSTP enzyme activity, and decrease senescence phenotype population induced by cardiotoxic agent such as DOX.

  6. Effects of dietary supplementation of modified zinc oxide on growth performance, nutrient digestibility, blood profiles, fecal microbial shedding and fecal score in weanling pigs.

    Science.gov (United States)

    Cho, Jin Ho; Upadhaya, Santi Devi; Kim, In Ho

    2015-06-01

    One hundred and forty piglets ((Landrace × Yorkshire) × Duroc, 21 day of age) with an initial weight of 6.50 ± 0.71 kg, were randomly allotted into four treatments to determine the effects of a modified form of zinc oxide (ZnO) on growth performance, nutrient digestibility, blood profiles, fecal microbial shedding and fecal score in weanling pigs. Dietary treatments were: (i) NC, negative control, basal diet containing zinc (Zn) from the premix; (ii) PC, positive control, basal diet containing Zn-free premix + 3000 ppm ZnO; (iii) H1, basal diet containing Zn-free premix + 3000 ppm ZnO (phase 1, days 1 to 14)/200 ppm modified ZnO (phase 2, days 15 to 42); (iv) H2, basal diet containing Zn-free premix + 300 ppm modified ZnO (phase 1)/200 ppm modified ZnO (phase 2). During days 1 to 14, average daily gains (ADG) were higher (P = 0.04) in PC, H1 and H2 groups than that in NC group. Overall, H1 treatment increased the ADG compared with NC (P = 0.05). On day 14, the alkaline phosphatase and plasma Zn concentration were increased (P = 0.01 and 0.04, respectively) in PC, H1 and H2 treatments compared with NC treatment. On days 14 and 42, the fecal Lactobacillus counts in NC group were lowest (P = 0.01, P = 0.04 respectively) among treatments. All supplemented groups showed lower (P = 0.03) fecal score than NC treatment on days 21 and 28. In conclusion, dietary supplementation with modified ZnO increased growth rates and reduced fecal scores in weanling pig. Modified ZnO could be used as a substitute to ZnO as a growth promoter and reduce Zn excretion to the environment because of the lower dosage. [Correction added on 3 February 2015, after first online publication: the initial weight of '6.50 ± 1.11 kg' has been replaced with '6.50 ± 0.71 kg' in the abstract.]. © 2015 Japanese Society of Animal Science.

  7. CdS Nanoparticle-Modified α-Fe2O3/TiO2 Nanorod Array Photoanode for Efficient Photoelectrochemical Water Oxidation.

    Science.gov (United States)

    Yin, Ruiyang; Liu, Mingyang; Tang, Rui; Yin, Longwei

    2017-09-02

    In this work, we demonstrate a facile successive ionic layer adsorption and reaction process accompanied by hydrothermal method to synthesize CdS nanoparticle-modified α-Fe 2 O 3 /TiO 2 nanorod array for efficient photoelectrochemical (PEC) water oxidation. By integrating CdS/α-Fe 2 O 3 /TiO 2 ternary system, light absorption ability of the photoanode can be effectively improved with an obviously broadened optical-response to visible light region, greatly facilitates the separation of photogenerated carriers, giving rise to the enhancement of PEC water oxidation performance. Importantly, for the designed abnormal type-II heterostructure between Fe 2 O 3 /TiO 2 , the conduction band position of Fe 2 O 3 is higher than that of TiO 2 , the photogenerated electrons from Fe 2 O 3 will rapidly recombine with the photogenerated holes from TiO 2 , thus leads to an efficient separation of photogenerated electrons from Fe 2 O 3 /holes from TiO 2 at the Fe 2 O 3 /TiO 2 interface, greatly improving the separation efficiency of photogenerated holes within Fe 2 O 3 and enhances the photogenerated electron injection efficiency in TiO 2 . Working as the photoanodes of PEC water oxidation, CdS/α-Fe 2 O 3 /TiO 2 heterostucture electrode exhibits improved photocurrent density of 0.62 mA cm - 2 at 1.23 V vs. reversible hydrogen electrode (RHE) in alkaline electrolyte, with an obviously negatively shifted onset potential of 80 mV. This work provides promising methods to enhance the PEC water oxidation performance of the TiO 2 -based heterostructure photoanodes.

  8. Enzymatically Modified Low-Density Lipoprotein Promotes Foam Cell Formation in Smooth Muscle Cells via Macropinocytosis and Enhances Receptor-Mediated Uptake of Oxidized Low-Density Lipoprotein.

    Science.gov (United States)

    Chellan, Bijoy; Reardon, Catherine A; Getz, Godfrey S; Hofmann Bowman, Marion A

    2016-06-01

    Enzyme-modified nonoxidized low-density lipoprotein (ELDL) is present in human atherosclerotic lesions. Our objective is to understand the mechanisms of ELDL uptake and its effects on vascular smooth muscle cells (SMC). Transformation of murine aortic SMCs into foam cells in response to ELDL was analyzed. ELDL, but not acetylated or oxidized LDL, was potent in inducing SMC foam cell formation. Inhibitors of macropinocytosis (LY294002, wortmannin, amiloride) attenuated ELDL uptake. In contrast, inhibitors of receptor-mediated endocytosis (dynasore, sucrose) and inhibitor of caveolae-/lipid raft-mediated endocytosis (filipin) had no effect on ELDL uptake in SMC, suggesting that macropinocytosis is the main mechanism of ELDL uptake by SMC. Receptor for advanced glycation end products (RAGE) is not obligatory for ELDL-induced SMC foam cell formation, but primes SMC for the uptake of oxidized LDL in a RAGE-dependent manner. ELDL increased intracellular reactive oxygen species, cytosolic calcium, and expression of lectin-like oxidized LDL receptor-1 in wild-type SMC but not in RAGE(-/-) SMC. The macropinocytotic uptake of ELDL is regulated predominantly by intracellular calcium because ELDL uptake was completely inhibited by pretreatment with the calcium channel inhibitor lacidipine in wild-type and RAGE(-/-) SMC. This is in contrast to pretreatment with PI3 kinase inhibitors which completely prevented ELDL uptake in RAGE(-/-) SMC, but only partially in wild-type SMC. ELDL is highly potent in inducing foam cells in murine SMC. ELDL endocytosis is mediated by calcium-dependent macropinocytosis. Priming SMC with ELDL enhances the uptake of oxidized LDL. © 2016 American Heart Association, Inc.

  9. Pure and Modified Co-Poly(amide-12-b-ethylene oxide Membranes for Gas Separation Studied by Molecular Investigations

    Directory of Open Access Journals (Sweden)

    Luana De Lorenzo

    2012-06-01

    Full Text Available This paper deals with a theoretical investigation of gas transport properties in a pure and modified PEBAX block copolymer membrane with N-ethyl-o/p-toluene sulfonamide (KET as additive molecules. Molecular dynamics simulations using COMPASS force field, Gusev-Suter Transition State Theory (TST and Monte Carlo methods were used. Bulk models of PEBAX and PEBAX/KET in different copolymer/additive compositions were assembled and analyzed to evaluate gas permeability and morphology to characterize structure-performance relationships.

  10. Cadmium Sulphide-Reduced Graphene Oxide-Modified Photoelectrode-Based Photoelectrochemical Sensing Platform for Copper(II Ions.

    Directory of Open Access Journals (Sweden)

    I Ibrahim

    Full Text Available A photoelectrochemical (PEC sensor with excellent sensitivity and detection toward copper (II ions (Cu2+ was developed using a cadmium sulphide-reduced graphene oxide (CdS-rGO nanocomposite on an indium tin oxide (ITO surface, with triethanolamine (TEA used as the sacrificial electron donor. The CdS nanoparticles were initially synthesized via the aerosol-assisted chemical vapor deposition (AACVD method using cadmium acetate and thiourea as the precursors to Cd2+ and S2-, respectively. Graphene oxide (GO was then dip-coated onto the CdS electrode and sintered under an argon gas flow (50 mL/min for the reduction process. The nanostructured CdS was adhered securely to the ITO by a continuous network of rGO that also acted as an avenue to intensify the transfer of electrons from the conduction band of CdS. The photoelectrochemical results indicated that the ITO/CdS-rGO photoelectrode could facilitate broad UV-visible light absorption, which would lead to a higher and steady-state photocurrent response in the presence of TEA in 0.1 M KCl. The photocurrent decreased with an increase in the concentration of Cu2+ ions. The photoelectrode response for Cu2+ ion detection had a linear range of 0.5-120 μM, with a limit of detection (LoD of 16 nM. The proposed PEC sensor displayed ultra-sensitivity and good selectivity toward Cu2+ ion detection.

  11. Bi-modified Pd/C catalyst via irreversible adsorption and its catalytic activity for ethanol oxidation in alkaline medium

    International Nuclear Information System (INIS)

    Cai, Jindi; Huang, Yiyin; Guo, Yonglang

    2013-01-01

    Highlights: • Pd-Bi/C catalysts were easily prepared by irreversible adsorption of Bi on Pd/C surface. • The adsorption of Bi increases the oxygen-containing species obviously on Pd-Bi/C surface. • Only a little amount of Bi on Pd-Bi/C can play a significant role in ethanol oxidation reaction (EOR). • Current density of EOR on Pd-Bi/C (20:1) is 2.4 times higher than that on Pd/C. • Anti-poisoning ability and durability of Pd-Bi/C (20:1) is greatly enhanced. -- Abstract: A facile approach to promote ethanol electro-oxidation on Pd-based catalysts is presented by the modification of Bi on Pd/C catalyst via irreversible adsorption. X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) measurements show that the modification of Bi has no significant effect on the Pd morphology and particle size distribution. Bi(III) and Pd(0) are the dominant forms in Pd-Bi/C catalyst. Electrochemical tests show that the modification of the appropriate amount of Bi on Pd/C catalyst can remarkably enhance activity toward ethanol oxidation reaction (EOR) up to about 2.4 times higher compared to Pd/C catalyst. The Pd-Bi/C (20:1) catalyst exhibits excellent stability and enhances CO tolerance. The enhanced electrochemical performance of Pd-Bi/C catalyst is attributed to the electronic effect and the bifunctional mechanism. The high exchange current density and the low apparent activation energy on Pd-Bi/C (20:1) catalyst reveal its faster kinetics and higher intrinsic activity compared to Pd/C catalyst

  12. A Sensor for the Determination of Lindane Using PANI/Zn, Fe(III Oxides and Nylon 6,6/MWCNT/Zn, Fe(III Oxides Nanofibers Modified Glassy Carbon Electrode

    Directory of Open Access Journals (Sweden)

    Omolola E. Fayemi

    2016-01-01

    Full Text Available A simple reproducible and environmentally friendly PANI/Zn, Fe(III and Nylon 6,6/MWCNT/Zn, Fe(III oxides nanofibers modified glassy carbon electrode was prepared and used for the electrochemical reduction of lindane. The modified electrodes offer a high sensing current for lindane. The modified electrodes were highly stable with respect to time, so that the single electrode can be used for the multiple analysis of the lindane sample. Cyclic voltammetry and square wave voltammetry were used as the sensing techniques. The dynamic range for the lindane determination was between 9.9 × 10−12 mol/L and 5 × 10−6 mol/L with detection limits of 51 and 32 nM for Nylon 6,6/MWCNT/ZnO and Nylon 6,6/MWCNT/Fe3O4 sensors, respectively. The LoD value reveals that the best electrode is Nylon 6,6/MWCNT/Fe3O4. The analytical utility of the proposed method was checked with drinking water samples.

  13. Effect of time and deposition method on quality of phosphonic acid modifier self-assembled monolayers on indium zinc oxide

    Energy Technology Data Exchange (ETDEWEB)

    Sang, Lingzi [Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721 (United States); Knesting, Kristina M. [Department of Chemistry, University of Washington, Seattle, WA 98195-1700 (United States); Bulusu, Anuradha [School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Sigdel, Ajaya K. [National Renewable Energy Laboratory, Golden, CO 80401 (United States); Giordano, Anthony J.; Marder, Seth R. [School of Chemistry and Biochemistry and Center for Organic Photonics and Electronics, Georgia Institute of Technology, Atlanta, GA 30332-0400 (United States); Berry, Joseph J. [National Renewable Energy Laboratory, Golden, CO 80401 (United States); Graham, Samuel [School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Ginger, David S. [Department of Chemistry, University of Washington, Seattle, WA 98195-1700 (United States); Pemberton, Jeanne E., E-mail: pembertn@email.arizona.edu [Department of Chemistry and Biochemistry, University of Arizona, Tucson, AZ 85721 (United States)

    2016-12-15

    Highlights: • Deposition of phosphonic acid monolayers on oxides from ethanol solutions occurs by rapid adsorption within 10 s with slower equilibration complete in 48 h. • The slower equilibration step involves molecular reorientation and vacancy filling on the oxide surface. • Soak-free deposition by spray coating and microcontact printing do not provide reproducible, fully-covered, uniform monolayers without substrate etching. • Adjustments to exposure time, substrate temperature, and solution/substrate contact efficiency are necessary to optimize soak-free methods. - Abstract: Phosphonic acid (PA) self-assembled monolayers (SAMs) are utilized at critical interfaces between transparent conductive oxides (TCO) and organic active layers in organic photovoltaic devices (OPVs). The effects of PA deposition method and time on the formation of close-packed, high-quality monolayers is investigated here for SAMs fabricated by solution deposition, micro-contact printing, and spray coating. The solution deposition isotherm for pentafluorinated benzylphosphonic acid (F{sub 5}BnPA) on indium-doped zinc oxide (IZO) is studied using polarization modulation-infrared reflection-absorption spectroscopy (PM-IRRAS) at room temperature as a model PA/IZO system. Fast surface adsorption occurs within the first min; however, well-oriented high-quality SAMs are reached only after ∼48 h, presumably through a continual process of molecular adsorption/desorption and monolayer filling accompanied by molecular reorientation. Two other rapid, soak-free deposition techniques, micro-contact printing and spray coating, are also explored. SAM quality is compared for deposition of phenyl phosphonic acid (PPA), F{sub 13}-octylphosphonic acid (F{sub 13}OPA), and pentafluorinated benzyl phosphonic acid (F{sub 5}BnPA) by solution deposition, micro-contact printing and spray coating using PM-IRRAS. In contrast to micro-contact printing and spray coating techniques, 48–168 h solution

  14. Spontaneous synthesis of gold nanoparticles on gum arabic-modified iron oxide nanoparticles as a magnetically recoverable nanocatalyst

    Science.gov (United States)

    2012-01-01

    A novel magnetically recoverable Au nanocatalyst was fabricated by spontaneous green synthesis of Au nanoparticles on the surface of gum arabic-modified Fe3O4 nanoparticles. A layer of Au nanoparticles with thickness of about 2 nm was deposited on the surface of gum arabic-modified Fe3O4 nanoparticles, because gum arabic acted as a reducing agent and a stabilizing agent simultaneously. The resultant magnetically recoverable Au nanocatalyst exhibited good catalytic activity for the reduction of 4-nitrophenol with sodium borohydride. The rate constants evaluated in terms of pseudo-first-order kinetic model increased with increase in the amount of Au nanocatalyst or decrease in the initial concentration of 4-nitrophenol. The kinetic data suggested that this catalytic reaction was diffusion-controlled, owing to the presence of gum arabic layer. In addition, this nanocatalyst exhibited good stability. Its activity had no significant decrease after five recycles. This work is useful for the development and application of magnetically recoverable Au nanocatalyst on the basis of green chemistry principles. PMID:22713480

  15. The Method of Coating Fe₃O₄ with Carbon Nanoparticles to Modify Biological Properties of Oxide Measured in Vitro.

    Science.gov (United States)

    Niemiec, Tomasz; Dudek, Mariusz; Dziekan, Natalia; Jaworski, Sławomir; Przewozik, Aleksandra; Soszka, Emilia; Koperkiewicz, Anna; Koczoń, Piotr

    2017-07-01

    The coating of nanoparticles on materials for medical application [e.g., the coating of Fe3O4 nanopowder (IONP) with a carbon nanolayer] serves to protect and modify the selected biological, physical, and chemical properties of the coated material. Increases in chemical stability, changes in biocompatibility, and a modified surface structure are examples of the effects caused by the formation of carbon coatings. In the current study, Fe3O4 nanoparticles were coated with a carbon nanolayer (IONP@C) in a plasmochemical reactor (using radio-frequency plasma-enhanced chemical vapor deposition methods) under various experimental conditions. Based on data from X-ray diffraction, Raman, and IR spectroscopy, the best processing parameters were determined in order to produce a carbon coating that would not change the structure of the IONP. The materials with the best cover, i.e., a uniform carbon nanolayer, were used in cytotoxic tests to investigate their biological properties using the human HepG2 hepatocarcinoma cell line and chicken embryo red blood cells as an in vitro model. The obtained results proved the low cytotoxicity of Fe3O4 micropowder and IONP in contrast to IONP@C, which reduced cell viability, increased hemolysis, and generally was more toxic than bare Fe3O4.

  16. The influence of surface microstructure and chemical composition on corrosion behaviour in fuel-grade bio-ethanol of low-alloy steel modified by plasma nitro-carburizing and post-oxidizing

    Science.gov (United States)

    Boniatti, Rosiana; Bandeira, Aline L.; Crespi, Ângela E.; Aguzzoli, Cesar; Baumvol, Israel J. R.; Figueroa, Carlos A.

    2013-09-01

    The interaction of bio-ethanol on steel surfaces modified by plasma-assisted diffusion technologies is studied for the first time. The influence of surface microstructure and chemical composition on corrosion behaviour of AISI 4140 low-alloy steel in fuel-grade bio-ethanol was investigated. The steel surfaces were modified by plasma nitro-carburizing followed plasma oxidizing. X-ray diffraction, scanning electron microscopy, optical microscopy, X-ray dispersive spectroscopy, and glow-discharge optical emission spectroscopy were used to characterize the modified surface before and after immersion tests in bio-ethanol up to 77 days. The main corrosion mechanism is pit formation. The pit density and pit size were measured in order to quantify the corrosion resistance which was found to depend more strongly on microstructure and morphology of the oxide layer than on its thickness. The best corrosion protection was observed for samples post-oxidized at 480 °C and 90 min.

  17. In Situ Synthesis and Characterization of Polyethyleneimine-Modified Carbon Nanotubes Supported PtRu Electrocatalyst for Methanol Oxidation

    Directory of Open Access Journals (Sweden)

    Xi Geng

    2015-01-01

    Full Text Available PtRu bimetallic nanoparticles were successfully synthesized on polyethyleneimine- (PEI- functionalized multiwalled carbon nanotubes (MWCNTs via an effective and facile polyol reduction approach. Noncovalent surface modification of MWCNTs with PEI was confirmed by FTIR and zeta potential measurements. The morphology, crystalline structure, and composition of the hybrid material were characterized by transmission electron microscopy (TEM, scanning electron microscopy (SEM, X-ray powder diffraction (XRD, and energy dispersive X-ray spectroscopy (EDX, respectively. According to SEM and TEM observations, PtRu nanoparticles with narrow size distribution were homogeneously deposited on PEI-MWCNTs. Cyclic voltammetry tests demonstrated that the as-prepared PtRu/PEI-MWCNTs nanocomposite had a large electrochemical surface area and exhibited enhanced electrocatalytic activity towards methanol oxidation in comparison with oxidized MWCNTs as catalyst support. PEI-functionalized CNTs, as useful building blocks for the assembly of Pt-based electrocatalyst, may have great potential for applications such as direct methanol fuel cell (DMFC.

  18. Synthesis and Properties of High Strength Thin Film Composites of Poly(ethylene Oxide and PEO-PMMA Blend with Cetylpyridinium Chloride Modified Clay

    Directory of Open Access Journals (Sweden)

    Mohammad Saleem Khan

    2015-01-01

    Full Text Available Ion-conducting thin film composites of polymer electrolytes were prepared by mixing high MW poly(ethylene oxide (PEO, poly(methyl methacrylate (PMMA as a polymer matrix, cetylpyridinium chloride (CPC modified MMT as filler, and different content of LiClO4 by using solution cast method. The crystallinity, ionic conductivity (σ, and mechanical properties of the composite electrolytes and blend composites were evaluated by using XRD, AC impedance, and UTM studies, respectively. The modification of clay by CPC showed enhancement in the d-spacing. The loading of clay has effect on crystallinity of PEO systems. Blend composites showed better mechanical properties. Young’s modulus and elongation at break values showed increase with salt and clay incorporation in pure PEO. The optimum composition composite of PEO with 3.5 wt% of salt and 3.3 wt% of CPMMT exhibited better performance.

  19. Utilization of Polyaniline (PAni) as Conductive Filler on Poly (Ethylene Oxide) / Poly (Vinyl Chloride) Films: Effects of Naphthalene as Surface Modifier on Electrical Conductivity

    Science.gov (United States)

    Yazid, Mohammed Izzuddeen Bin Mohd; Ghani, Supri A.; Jin, Tan Soo; Fazlina Osman, Azlin; Din, Siti Hajar Mohd

    2017-10-01

    The aim of the study was to utilize polyaniline (PAni) as conductive filler in poly (ethylene oxide) / poly (vinyl chloride) (PEO/PVC) films. Naphthalene was used as surface modifier to increase the properties of PEO/PVC/PAni films. The electrical conductivity of PEO/PVC/PAni film improved with higher loading of PAni until it reached the percolation threshold at 10 wt%. Moreover, the conductivity of the films also improved with the addition of naphthalene compared to the films without naphthalene. These enhancements were due to the improved interfacial bonding between PEO/PVC blend and PAni, which were supported by scanning electron microscopy (SEM) analysis. In addition, no new chemical bonding was created with the incorporation of naphthalene as proved by the FTIR analysis.

  20. Preparation and optical characterization of lanthanum modified lead zirconate titanate thin films on indium-doped tin oxide-coated glass substrate

    International Nuclear Information System (INIS)

    Khodorov, A.; Gomes, M.J.M.

    2006-01-01

    Lanthanum modified lead zirconate titanate (PLZT) thin films were fabricated on indium-doped tin oxide (ITO)-coated glass substrate by sol-gel method. The structure of the films was characterized with X-ray diffraction and scanning electron microscopy. The optical properties were investigated in the wavelength range of 220-2400 nm. The sample was modelled as a three layer structure on finite substrate, and optical constants of this system were calculated from the transmission and reflection spectra. The calculated dielectric function was fitted with the Drude model in the case of ITO and a sum of Lorentzian oscillators in the case of PLZT films. For PLZT film the anomalous behaviour of imaginary part of dielectric function was observed below the absorption edge. The possible reasons of that behaviour were discussed

  1. Thermoelectric Properties and Microstructure of Modified Novel Complex Cobalt Oxides Sr3RECo4O10.5 (RE = Y, Gd)

    DEFF Research Database (Denmark)

    Van Nong, Ngo; Pryds, Nini

    2012-01-01

    We report on the high-temperature thermoelectric properties and microstructure of modified novel complex cobalt oxides Sr3RECo4O10.5 (RE = Y, Gd), in which the Sr- and Co-sites are partly substituted by Ca and Ga, respectively. We have found that the sample with RE = Gd shows a significant higher...... of the thermoelectric power factor (sigma S-2). At 1150 K, the highest sigma S-2 value attains for the Sr2CaGdCo3.9Ga0.1O10.5 sample about 60 mu Wm(-1)K(-2), which is 8 times larger than the Sr3GdCo4O10.5 counter-part. Interestingly, although microstructure shows a clear evolution of the grains for the Ga and Ca doped...

  2. Selective catalytic reduction of nitric oxide by ethylene over metal-modified ZSM-5- and {gamma}-Al{sub 2}O{sub 3}-catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Eraenen, K.; Kumar, N.; Lindfors, L.E. [Aabo Akademi, Turku (Finland). Lab. of Industrial Chemistry

    1996-12-31

    Metal-modified ZSM-5 and {gamma}-Al{sub 2}O{sub 3} catalysts were tested in reduction of nitric oxide by ethylene. Different metals were introduced into the ZSM-5 catalyst by ion-exchange and by introduction of metals during the zeolite synthesis. To prepare bimetallic catalysts a combination of these methods was used. The {gamma}-Al{sub 2}O{sub 3} was impregnated with different metals by the incipient wetness technique and by adsorption. Activity measurements showed that the ZSM-5 based catalysts were more active than the {gamma}-Al{sub 2}O{sub 3} based catalysts. The highest conversion was obtained over a ZSM-5 catalyst prepared by introduction of Pd during synthesis of the zeolite and subsequently ion-exchanged with copper. (author)

  3. Diesel/biodiesel soot oxidation with ceo2 and ceo2-zro2-modified cordierites: a facile way of accounting for their catalytic ability in fuel combustion processes

    Directory of Open Access Journals (Sweden)

    Rodrigo F. Silva

    2011-01-01

    Full Text Available CeO2 and mixed CeO2-ZrO2 nanopowders were synthesized and efficiently deposited onto cordierite substrates, with the evaluation of their morphologic and structural properties through XRD, SEM, and FTIR. The modified substrates were employed as outer heterogeneous catalysts for reducing the soot originated from the diesel and diesel/biodiesel blends incomplete combustion. Their activity was evaluated in a diesel stationary motor, and a comparative analysis of the soot emission was carried out through diffuse reflectance spectroscopy. The analyses have shown that the catalyst-impregnated cordierite samples are very efficient for soot oxidation, being capable of reducing the soot emission in more than 60%.

  4. Extracellular biosynthesis of gadolinium oxide (Gd2O3 nanoparticles, their biodistribution and bioconjugation with the chemically modified anticancer drug taxol

    Directory of Open Access Journals (Sweden)

    Shadab Ali Khan

    2014-03-01

    Full Text Available As a part of our programme to develop nanobioconjugates for the treatment of cancer, we first synthesized extracellular, protein-capped, highly stable and well-dispersed gadolinium oxide (Gd2O3 nanoparticles by using thermophilic fungus Humicola sp. The biodistribution of the nanoparticles in rats was checked by radiolabelling with Tc-99m. Finally, these nanoparticles were bioconjugated with the chemically modified anticancer drug taxol with the aim of characterizing the role of this bioconjugate in the treatment of cancer. The biosynthesized Gd2O3 nanoparticles were characterized by UV–vis spectroscopy, transmission electron microscopy (TEM, X-ray diffraction (XRD and X-ray photoemission spectroscopy (XPS. The Gd2O3–taxol bioconjugate was confirmed by UV–vis spectroscopy and fluorescence microscopy and was purified by using high performance liquid chromatography (HPLC.

  5. Quantification of modifiers in advanced materials based on zinc oxide by total reflection X-ray fluorescence and inductively coupled plasma mass spectrometry

    Science.gov (United States)

    Filatova, Daria G.; Alov, Nikolai V.; Vorobyeva, Natalia A.; Rumyantseva, Marina N.; Sharanov, Pavel Yu.; Seregina, Irina F.; Gaskov, Alexander M.

    2016-04-01

    A novel approach to quantification of Ga and Zn modifiers in advanced materials based on zinc oxide is presented. The approach includes a combination of total reflection X-ray fluorescence (TXRF) and inductively coupled plasma mass spectrometry (ICP-MS) for determination and validation of the results. It is suggested to use aqueous standards for the direct determination of elements in powder samples by TXRF with a relative standard deviation no more than sr = 0.11. The accuracy of these results was proved by ICP-MS after the sample decomposition, sr(In) = 0.05, sr(Ga) = 0.06 and sr(Zn) = 0.06. It was established that there is a possibility to determine indium above 300 ppb on the background of K-M3 line of argon.

  6. Glassy carbon electrode modified with horse radish peroxidase/organic nucleophilic-functionalized carbon nanotube composite for enhanced electrocatalytic oxidation and efficient voltammetric sensing of levodopa

    Energy Technology Data Exchange (ETDEWEB)

    Shoja, Yalda; Rafati, Amir Abbas, E-mail: aa_rafati@basu.ac.ir; Ghodsi, Javad

    2016-01-01

    A novel and selective enzymatic biosensor was designed and constructed for voltammetric determination of levodopa (L-Dopa) in aqueous media (phosphate buffer solution, pH = 7). Biosensor development was on the basis of to physically immobilizing of horse radish peroxidase (HRP) as electrochemical catalyst by sol–gel on glassy carbon electrode modified with organic nucleophilic carbon nanotube composite which in this composite p-phenylenediamine (pPDA) as organic nucleophile chemically bonded with functionalized MWCNT (MWCNT-COOH). The results of this study suggest that prepared bioorganic nucleophilic carbon nanotube composite (HRP/MWCNT-pPDA) shows fast electron transfer rate for electro oxidation of L-Dopa because of its high electrochemical catalytic activity toward the oxidation of L-Dopa, more −NH{sub 2} reactive sites and large effective surface area. Also in this work we measured L-Dopa in the presence of folic acid and uric acid as interferences. The proposed biosensor was characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), FT-IR spectroscopy and cyclic voltammetry (CV). The differential pulse voltammetry (DPV) was used for determination of L-Dopa from 0.1 μM to 1.9 μM with a low detection limit of 40 nM (for S/N = 3) and sensitivity was about 35.5 μA/μM. Also this biosensor has several advantages such as rapid response, high stability and reproducibility. - Highlights: • Glassy carbon electrode modified by a novel composite in which pPDA as nucleophile is chemically attached to MWCNTs. • The developed biosensor exhibited excellent electrocatalytic activity in electrochemically determination of L-Dopa. • The biosensor showed acceptable sensitivity, reproducibility, detection limit, selectivity and stability. • MWCNT-pPDA provides a good electrical conductivity and large effective surface area for enzyme immobilization.

  7. Modified surface morphology of a novel Ti-24Nb-4Zr-7.9Sn titanium alloy via anodic oxidation for enhanced interfacial biocompatibility and osseointegration.

    Science.gov (United States)

    Li, Xiang; Chen, Tao; Hu, Jing; Li, Shujun; Zou, Qin; Li, Yunfeng; Jiang, Nan; Li, Hui; Li, Jihua

    2016-08-01

    The Ti-24Nb-4Zr-7.9Sn titanium alloy (Ti2448) has shown potential for use in biomedical implants, because this alloy possesses several important mechanical properties, such as a high fracture strength, low elastic modulus, and good corrosion resistance. In this study, we aimed to produce a hierarchical nanostructure on the surface of Ti2448 to endow this alloy with favorable biological properties. The chemical composition of Ti2448 (64.0wt% Ti, 23.9wt% Nb, 3.9wt% Zr, and 8.1wt% Sn) gives this material electrochemical properties that lead to the generation of topographical features under standard anodic oxidation. We characterized the surface properties of pure Ti (Ti), nanotube-Ti (NT), Ti2448, and nanotube-Ti2448 (NTi2448) based on surface morphology (scanning electron microscopy and atomic force microscopy), chemical and phase compositions (X-ray diffraction and X-ray photoelectron spectroscopy), and wettability (water contact angle). We evaluated the biocompatibility and osteointegration of implant surfaces by observing the behavior of bone marrow stromal cells (BMSCs) cultured on the surfaces in vitro and conducting histological analysis after in vivo implantation of the modified materials. Our results showed that a hierarchical structure with a nanoscale bone-like layer was achieved along with nanotube formation on the Ti2448 surface. The surface characterization data suggested the superior biocompatibility of the NTi2448 surface in comparison with the Ti, NT, and Ti2448 surfaces. Moreover, the NTi2448 surface showed better biocompatibility for BMSCs in vitro and better osteointegration in vivo. Based on these results, we conclude that anodic oxidation facilitated the formation of a nanoscale bone-like structure and nanotubes on Ti2448. Unlike the modified titanium surfaces developed to date, the NTi2448 surface, which presents both mechanical compatibility and bioactivity, offers excellent biocompatibility and osteointegration, suggesting its potential for

  8. Immobilization of glucose oxidase onto a novel platform based on modified TiO2 and graphene oxide, direct electrochemistry, catalytic and photocatalytic activity

    International Nuclear Information System (INIS)

    Haghighi, Nasibeh; Hallaj, Rahman; Salimi, Abdollah

    2017-01-01

    In this work a new organic–inorganic nanocomposite has been introduced for enzyme immobilization. The composite consisting of graphene oxide (GO) and titanium oxide nanoparticles (TiO 2 ) modified with 2, 2′-dithioxo-3, 3′-bis (3-(triethoxysilyl) propyl)-2H, 2′H-[5, 5′-bithiazolylidene]-4, 4′(3H, 3′H)-dione as Organic-Inorganic Supporting Ligand (OISL). The OISL was covalently attached to TiO 2 nanoparticles and employed for obtaining a suitable solid surface to enzyme attachment. The glucose oxidase (GOD) was irreversibly loaded on the GC/GO/TiO 2 -OISL using consecutive cyclic voltammetry. The enzyme immobilization and the enzymatic activity were determined by electrochemical methods. The cyclic voltammogram displayed a pair of well-defined and nearly symmetric redox peaks with a formal potential of − 0.465 V and an apparent electron transfer rate constant of 1.74 s −1 . The GO/TiO 2 -OISL can catalyze the electroreduction and electrooxidation of hydrogen peroxide. The GC/GO/TiO 2 -OISL/GOD electrode was used in the hydrogen peroxide determination. The fabricated nanobiocomposite shows dramatic photoelectrocatalytic activity which evaluated by studying the electrocatalytic activity of the fabricated electrode toward hydrogen peroxide in darkness and in the presences of light. - Highlights: • In this work a novel platform used to successful immobilization of glucose oxidase. Due to its large functional group this modified nanoparticles load enzyme (GOD) and remain enzyme whit out denaturation for a long time. • The loaded enzyme shows direct electron transfer and excellent charge transfer kinetic. Also the fabricated nano-bio-composite has good catalytic activity toward hydrogen peroxide during electrooxidation and electro reduction process. • The nano-bio-composite shows excellent photocatalytic activity.

  9. Electrochemically reduced graphene oxide-modified screen-printed carbon electrodes for a simple and highly sensitive electrochemical detection of synthetic colorants in beverages.

    Science.gov (United States)

    Jampasa, Sakda; Siangproh, Weena; Duangmal, Kiattisak; Chailapakul, Orawon

    2016-11-01

    A simple and highly sensitive electrochemical sensor based on an electrochemically reduced graphene oxide-modified screen-printed carbon electrode (ERGO-SPCE) for the simultaneous determination of sunset yellow (SY) and tartrazine (TZ) was proposed. An ERGO film was coated onto the electrode surface using a cyclic voltammetric method and then characterized by scanning electron microscopy (SEM). In 0.1M phosphate buffer at a pH of 6, the two oxidation peaks of SY and TZ appeared separately at 0.41 and 0.70V, respectively. Surprisingly, the electrochemical response remarkably increased approximately 90- and 20-fold for SY and TZ, respectively, using the modified electrode in comparison to the unmodified electrode. The calibration curves exhibited linear ranges from 0.01 to 20.0µM for SY and from 0.02 to 20.0µM for TZ. The limits of detection were found to be 0.50 and 4.50nM (at S/N=3) for SY and TZ, respectively. Furthermore, this detection platform provided very high selectivity for the measurement of both colorants. This electrochemical sensor was successfully applied to determine the amount of SY and TZ in commercial beverages. Comparison of the results obtained from this proposed method to those obtained by an in-house standard technique proved that this developed method has good agreement in terms of accuracy for practical applications. This sensor offers an inexpensive, rapid and sensitive determination. The proposed system is therefore suitable for routine analysis and should be an alternative method for the analysis of food colorants. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Nanocomposites of zeolite-titanium(IV) oxides: Preparation, characterization, adsorption, photocatalytic and bactericidal properties

    Science.gov (United States)

    Domoroshchina, Elena; Kravchenko, Galina; Kuz'micheva, Galina

    2017-06-01

    NT/zeolite nanocomposites (NT - nanosized titanium(IV) oxides: η-phase and Hombifine N with anatase; zeolite: Beta(25), ZSM-5 with different modules Si/Al, MOR, or Y) have been obtained by two methods: modified cold-impregnation method (method 1) and in situ method of introduction of zeolites into the reaction mixture during the synthesis of NT by hydrolysis of TiOSO4×xH2SO4×yH2O or TiOSO4×2H2O aqueous solutions (method 2), performed for the first time. According to the X-ray data, the following differences in the NT:zeolite systems under investigation have been revealed: the mixture of zeolites and NT in nanocrystalline (Hombifine N/zeolite) or amorphous states (η-phase/zeolite, except for η-phase/MOR, where NT peaks are absent) (method 1), and the mixture of Y-zeolite and amorphous NT or only Y-zeolite without NT (method 2), which indicates the different levels of interaction between NT and zeolites in the systems studied. The best characteristics of properties (photocatalytic, adsorption, and antibacterial) have been revealed in the nanocomposites synthesized by the method 2. The correlation between the photoreaction rate constant (the k value) under UV irradiation in the presence of nanocomposites (kmax for NT/ZSM-5(12)) and the type of precursor, its pH, synthesis duration, NT:zeolite ratio, organic dye composition (methyl orange or Rhodamine G) has been established. The highest degree of extraction of P(V) ions from model aqueous systems has been observed in the presence of nanocomposites with the largest total surface area of all particles (Rmax = 99.48% for NT/MOR). The correlation between the sorption degree of P(V) ions and the modulus of zeolite is possible. Antibacterial activity in the dark towards Escherichia coli has been found for Y and Beta(25) zeolites and nanocomposites on their basis (methods 1 and 2) with the maximum diameter of bacterial growth inhibition (18 mm) obtained for NT/Beta(25) (method 2) synthesized only from TiOSO4×xH2SO4

  11. Very sensitive electrochemical determination of diuron on glassy carbon electrode modified with reduced graphene oxide-gold nanoparticle-Nafion composite film.

    Science.gov (United States)

    Zarei, K; Khodadadi, A

    2017-10-01

    In this work, a very sensitive electrochemical sensor based on glassy carbon electrode (GCE) modified with reduced graphene oxide-gold nanoparticles/Nafion (rGO-AuNPs/Nafion) composite film was applied to determine diuron. Synthesized GO was characterized using X-ray diffraction (XRD) and UV-visible spectroscopy. The surface morphology of the rGO-AuNPs/Nafion film was also characterized using scanning electron microscopy and electrochemical impedance spectroscopy. Cyclic voltammetry (CV) and adsorptive differential pulse voltammetry (AdDPV) were applied to investigate the electrochemical response of the diuron on the modified electrode. The electrode showed a linear response at 1.0×10 -9 -1.0×10 -7 M and a detection limit of 0.3nM under the optimized conditions. The effect of some other species on the determination of diuron was investigated and the sensor showed good selectivity for determination of diuron. The constructed sensor was applied to determine diuron in enriched samples of orange juice, mineral and tap water which statistical t-test showed accuracy of method. Also the sensor was applied to obtain diuron content in the tea sample. The reliability of the proposed sensor was confirmed after comparing the results with those obtained using high performance liquid chromatography (HPLC) as a comparative method. Copyright © 2017 Elsevier Inc. All rights reserved.

  12. Physicochemical properties of poly(ethylene oxide)-based composite polymer electrolytes with a silane-modified mesoporous silica SBA-15

    Energy Technology Data Exchange (ETDEWEB)

    Shen Chen [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Wang, Jianming [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China)], E-mail: wjm@zju.edu.cn; Tang Zheng; Wang Huijuan; Lian Huiqin [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); Zhang Jianqing; Cao Chunan [Department of Chemistry, Zhejiang University, Hangzhou 310027 (China); State Key Laboratory for Corrosion and Protection of Metal, Institute of Metal Research, Chinese Academy of Sciences, 62 Wencui Road, Shenyang 110016 (China)

    2009-04-30

    Mesoporous silica SBA-15 was surface-modified by {gamma}-glycidoxypropyltrimethoxy silane (GPTMS), and novel poly(ethylene oxide) (PEO)-based composite polymer electrolytes (CPE) using the silane-modified SBA-15 (SBA-15-GPTMS) as filler were prepared and characterized. The results of the low-angle X-ray diffraction (XRD) patterns and Fourier-transform infrared (FT-IR) spectroscopy indicated that GPTMS has been successfully attached to the surface of SBA-15 with a high degree of mesoscopic hexagonal pore structure. The incorporation of SBA-15-GPTMS in the PEO-LiClO{sub 4} matrix effectively reduced the PEO crystallinity and obviously improved the conductivity and electrochemical stability of the CPEs. The CPE with 10 wt.% SBA-15-GPTMS provided the highest conductivity among all the tested CPEs, about 2-3 orders of magnitude higher than that of the PEO-LiClO{sub 4} matrix below the melting temperature of PEO. The reasons that the CPEs using SBA-15-GPTMS as filler showed higher conductivity than that with SBA-15 were discussed.

  13. Impedimetric Salmonella aptasensor using a glassy carbon electrode modified with an electrodeposited composite consisting of reduced graphene oxide and carbon nanotubes

    International Nuclear Information System (INIS)

    Jia, Fei; Dai, Ruitong; Duan, Nuo; Wu, Shijia; Wang, Zhouping; Li, Xingmin

    2016-01-01

    We describe a Salmonella biosensor that was obtained by electrochemical immobilization of a nanocomposite consisting of reduced graphene oxide (rGO) and carboxy-modified multi-walled carbon nanotubes (MWCNTs) directly on the surface of a glassy carbon electrode (GCE). An amino-modified aptamer specific for Salmonella was covalently bound to the rGO-MWCNT composite via amide bonds. The morphology of the rGO-MWCNT nanocomposite was characterized by transmission electron microscopy and scanning electron microscopy. Cyclic voltammetry and electrochemical impedance spectroscopy were used to monitor all steps during assembly. When exposed to samples containing Salmonella, the anti-Salmonella aptamer on the electrode captures its target. Hence, electron transfer is blocked, and this results in a large increase in impedance. Salmonella can be quantified by this aptasensor, typically operated at a working voltage of 0.2 V (vs. Ag/AgCl), in the range from 75 to 7.5 × 10 5 cfu⋅mL −1 and detection limit of 25 cfu⋅mL −1 (at an S/N of 3). The method is perceived to have a wide scope in that other bacteria may be detected by analogy to this approach and with very low limits of detection by applying respective analyte-specific aptamers. (author)

  14. Single cell imprinting on the surface of Ag-ZnO bimetallic nanoparticle modified graphene oxide sheets for targeted detection, removal and photothermal killing of E. Coli.

    Science.gov (United States)

    Roy, Ekta; Patra, Santanu; Tiwari, Ashutosh; Madhuri, Rashmi; Sharma, Prashant K

    2017-03-15

    A very cost-effective, fast, sensitive and specific imprinted polymer modified electrochemical sensor for the targeted detection, removal and destruction of Escherichia coli bacteria was developed onto the surface of Ag-ZnO bimetallic nanoparticle and graphene oxide nanocomposite. The nanocomposite played a dual role in this work, as a platform for imprinting of bacteria as well as a participated in their laser-light induced photo killing. In terms of sensing, our proposed sensor can detect E. Coli as few as 10CFUmL -1 and capture 98% of bacterial cells from their very high concentrated solution (10 5 CFUmL -1 ). Similarly to the quantitative detection, we have also investigated the quantitative destruction of E. Coli and found that 16.0cm 2 area of polymer modified glass plate is sufficient enough to kill 10 5 CFUmL -1 in the small time span of 5 minutes. The obtained results suggest that our proposed sensor have potential to serve as a promising candidate for specific and quantitative detection, removal as well as the destruction of a variety of bacterial pathogens. Copyright © 2015 Elsevier B.V. All rights reserved.

  15. Efficient and Air-Stable Planar Perovskite Solar Cells Formed on Graphene-Oxide-Modified PEDOT:PSS Hole Transport Layer

    Science.gov (United States)

    Luo, Hui; Lin, Xuanhuai; Hou, Xian; Pan, Likun; Huang, Sumei; Chen, Xiaohong

    2017-10-01

    As a hole transport layer, PEDOT:PSS usually limits the stability and efficiency of perovskite solar cells (PSCs) due to its hygroscopic nature and inability to block electrons. Here, a graphene-oxide (GO)-modified PEDOT:PSS hole transport layer was fabricated by spin-coating a GO solution onto the PEDOT:PSS surface. PSCs fabricated on a GO-modified PEDOT:PSS layer exhibited a power conversion efficiency (PCE) of 15.34%, which is higher than 11.90% of PSCs with the PEDOT:PSS layer. Furthermore, the stability of the PSCs was significantly improved, with the PCE remaining at 83.5% of the initial PCE values after aging for 39 days in air. The hygroscopic PSS material at the PEDOT:PSS surface was partly removed during spin-coating with the GO solution, which improves the moisture resistance and decreases the contact barrier between the hole transport layer and perovskite layer. The scattered distribution of the GO at the PEDOT:PSS surface exhibits superior wettability, which helps to form a high-quality perovskite layer with better crystallinity and fewer pin holes. Furthermore, the hole extraction selectivity of the GO further inhibits the carrier recombination at the interface between the perovskite and PEDOT:PSS layers. Therefore, the cooperative interactions of these factors greatly improve the light absorption of the perovskite layer, the carrier transport and collection abilities of the PSCs, and especially the stability of the cells.

  16. Graphene and graphene oxide modified by deep eutectic solvents and ionic liquids supported on silica as adsorbents for solid-phase extraction

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiaoqin; Li, Guizhen; Row, Kyung Ho [Dept. of Chemistry and Chemical Engineering, Inha University, Incheon (Korea, Republic of)

    2017-02-15

    A novel deep eutectic solvent (DES) and ionic liquid (IL)-modified graphene (G) and graphene oxide (GO) were synthesized and used as effective adsorbents for the preconcentration of three chlorophenols (CPs), 4-chlorophenol (4-CP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP), in environmental water samples prior to high-performance liquid chromatography (HPLC). The new materials were characterized by scanning electron microscopy (S-4200) and Fourier-transform infrared spectrometry. The prepared functionalized GO@silica shows remarkable adsorption capacity toward CPs. When used as solid-phase extraction (SPE) sorbents, a superior recovery (88.49–89.70%) could be obtained compared to commercial sorbents, such as silica and aminosilica. Based on this, a method for the analysis of CPs in water samples was established by coupling SPE with HPLC. These results highlight the potential new role of DES and IL-modified GO in the preparation of analytical samples.

  17. Citric Acid-Modified Fenton's Reaction for the Oxidation of Chlorinated Ethylenes in Soil Solution Systems

    Energy Technology Data Exchange (ETDEWEB)

    Seol, Yongkoo; Javandel, Iraj

    2008-03-15

    Fenton's reagent, a solution of hydrogen peroxide and ferrous iron catalyst, is used for an in-situ chemical oxidation of organic contaminants. Sulfuric acid is commonly used to create an acidic condition needed for catalytic oxidation. Fenton's reaction often involves pressure buildup and precipitation of reaction products, which can cause safety hazards and diminish efficiency. We selected citric acid, a food-grade substance, as an acidifying agent to evaluate its efficiencies for organic contaminant removal in Fenton's reaction, and examined the impacts of using citric acid on the unwanted reaction products. A series of batch and column experiments were performed with varying H{sub 2}O{sub 2} concentrations to decompose selected chlorinated ethylenes. Either dissolved iron from soil or iron sulfate salt was added to provide the iron catalyst in the batch tests. Batch experiments revealed that both citric and sulfuric acid systems achieved over 90% contaminant removal rates, and the presence of iron catalyst was essential for effective decontamination. Batch tests with citric acid showed no signs of pressure accumulation and solid precipitations, however the results suggested that an excessive usage of H{sub 2}O{sub 2} relative to iron catalysts (Fe{sup 2+}/H{sub 2}O{sub 2} < 1/330) would result in lowering the efficiency of contaminant removal by iron chelations in the citric acid system. Column tests confirmed that citric acid could provide suitable acidic conditions to achieve higher than 55% contaminant removal rates.

  18. Factors affecting the photovoltaic behavior of inverted polymer solar cells using various indium tin oxide electrodes modified by amines with simple chemical structures

    Energy Technology Data Exchange (ETDEWEB)

    Kusumi, Takuji [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192 (Japan); Kuwabara, Takayuki, E-mail: tkuwabar@se.kanazawa-u.ac.jp [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192 (Japan); Research Center for Sustainable Energy and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192 (Japan); Yamaguchi, Takahiro [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192 (Japan); Taima, Tetsuya [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192 (Japan); Research Center for Sustainable Energy and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192 (Japan); Takahashi, Kohshin, E-mail: ktakaha@se.kanazawa-u.ac.jp [Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192 (Japan); Research Center for Sustainable Energy and Technology, Kanazawa University, Kakuma-machi, Kanazawa, Ishikawa 920-1192 (Japan)

    2015-09-30

    In a glass–indium tin oxide (ITO)/amine/regioregular poly(3-hexylthiophene) (P3HT):[6,6]-phenyl C{sub 61} butyric acid methyl ester (PCBM)/poly(3,4-ethylenedioxylenethiophene):poly(4-styrene sulfonic acid) (PEDOT:PSS)/Au cell, which uses small molecule amine-modified ITO as the electron collection electrode, a light-soaking effect under irradiation of simulated sunlight was restrained considerably compared with in an ITO/P3HT:PCBM/PEDOT:PSS/Au cell containing bare ITO. That is, the time taken to arrive at a saturated V{sub oc} from the initial V{sub oc} became short when the ionization potential (I{sub P}) of ITO reduced by the amine modification, and consequently both of its saturated V{sub oc} and power conversion efficiency (PCE) improved. The I{sub P} decreased with an increase in the number (N) of amino groups in a single amine molecule, because the basic amino groups can efficiently neutralize any acidic hydroxyl groups on ITO through a multipoint interaction. The superior performance of the cell containing the amine-modified electrode with large N was perhaps because the energy mismatch formed by a contact between ITO and acceptor PCBM reduced, and consequently the rate of electron collection at ITO increased. - Highlights: • Surface-modification of ITO electrode with low molecular weight amines • Ionization potential of ITO was decreased by forming an electrical double layer. • Light-soaking effect has been observed by irradiating white light. • The light-soaking effect mainly improved the open-circuit photovoltage. • Open-circuit photovoltage was limited by ionization potential of amine-modified ITO.

  19. Facile Synthesis of Pt-/Pd-MODIFIED NiTi Electrode with Superior Electro-Catalytic Activities Toward Methanol, Ethanol and Ethylene Glycol Oxidation

    Science.gov (United States)

    He, Yongwei; Wang, Mei; Ma, Zizai; Li, Ruixue; Kundu, Manab; Ma, Guanshui; Lin, Naiming; Tang, Bin; Wang, Xiaoguang

    2016-11-01

    Surface functional modification of NiTi electrode with noble Pt and Pd metal has been successfully carried out by simple and cost effective electro-spark deposition technique (ESD). Thin-film X-ray diffraction (TF-XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and cyclic voltammetry (CV) have been carried out in order to investigate the structure, morphology, chemical composition and electrochemical behavior of the modified electrode surface. The modified Pt/NiTi and Pd/NiTi electrode surface exhibit a circular splash pattern with a tiny amount of Pt (˜5.30 at.% Pt) and Pd (˜5.71 at.% Pd) existence. The electrochemical results demonstrate that the Pt/NiTi and Pd/NiTi electrode possess an improved electro-catalytic activities toward methanol (MeOH), ethanol (EtOH) and ethylene glycol (EG) oxidation in alkaline media in comparison with the bare NiTi electrode. In acidic environments, the Pt/NiTi electrode exhibits even much better catalytic activities than the pure Pt sheet electrode due to the bi-functional mechanism. In the same way, the electro-catalytic activity of the modified Pd/NiTi electrode is also slightly larger than that of the pure Pd sheet electrode in alkaline environment. The electro-spark surface modification approach is rapid and environmentally-benign, being attractive to widen the application of traditional surface modification technique in the field of material surface/interface design and functionalization.

  20. Fabrication of Bi modified Bi2S3 pillared g-C3N4 photocatalyst and its efficient photocatalytic reduction and oxidation performances

    Science.gov (United States)

    Chen, Dongdong; Fang, Jianzhang; Lu, Shaoyou; Zhou, GuangYing; Feng, Weihua; Yang, Fan; Chen, Yi; Fang, ZhanQiang

    2017-12-01

    A novel efficient Bi modified Bi2S3 pillared g-C3N4 (BBC) plasmonic semiconductor photocatalyst has been successfully developed in a mixed solvothermal environment. The photocatalytic abilities of the as-prepared samples are examined by the photocatalytic reduction of Cr(VI) and oxidation of tetracycline (TC). And the chemical composition, structure, morphology and photo-absorption properties of the photocatalysts have been investigated by XRD, FT-IR, XPS, TEM, HRTEM and DRS methods, respectively. It is found that the addition of triethanolamine (TEA) results in the formation of the pillared-g-C3N4 (PG) nanostructure. The agglomeration of g-C3N4 nanosheets moiety and Bi2S3 nanorods moiety can be both hindered effectively by the special PG structure. And the photocatalytic results indicate that BBC exhibits the best photoreduction and photooxidation performances among all the samples, and meanwhile possesses superior photo-stability during the recycling runs. The enhanced photocatalytic activity of BBC could be ascribed to the furtherance of charge separation, localized surface plasma resonance (SPR) effect of metallic Bi and the excellent reaction interface. Finally, a tentative mechanism of BBC for photocatalytic reduction of Cr(VI) and oxidation of TC is discussed in detail.

  1. Ion Implantation-Modified Fluorine-Doped Tin Oxide by Zirconium with Continuously Tunable Work Function and Its Application in Perovskite Solar Cells.

    Science.gov (United States)

    Han, Dong; Wu, Cuncun; Zhao, Yunbiao; Chen, Yi; Xiao, Lixin; Zhao, Ziqiang

    2017-12-06

    In recent years, perovskite solar cells have drawn a widespread attention. As an electrode material, fluorine-doped tin oxide (FTO) is widely used in various kinds of solar cells. However, the relatively low work function (WF) (∼4.6 eV) limits its application. The potential barrier between the transparent conductive oxide electrode and the hole transport layer (HTL) in inverted perovskite solar cells results in a decrease in device performance. In this paper, we propose a method to adjust WF of FTO by implanting zirconium ions into the FTO surface. The WF of FTO can be precisely and continuously tuned between 4.59 and 5.55 eV through different dopant concentration of zirconium. In the meantime, the modified FTO, which had a WF of 5.1 eV to match well the highest occupied molecular orbital energy level of poly(3,4-ethylenedioxylenethiophene):polystyrene sulfonate, was used as the HTL in inverted planar perovskite solar cells. Compared with the pristine FTO electrode-based device, the open circuit voltage increased from 0.82 to 0.91 V, and the power conversion efficiency increased from 11.6 to 14.0%.

  2. Treatment of high salt oxidized modified starch waste water using micro-electrolysis, two-phase anaerobic aerobic and electrolysis for reuse

    Science.gov (United States)

    Yi, Xuenong; Wang, Yulin

    2017-06-01

    A combined process of micro-electrolysis, two-phase anaerobic, aerobic and electrolysis was investigated for the treatment of oxidized modified starch wastewater (OMSW). Optimum ranges for important operating variables were experimentally determined and the treated water was tested for reuse in the production process of corn starch. The optimum hydraulic retention time (HRT) of micro-electrolysis, methanation reactor, aerobic process and electrolysis process were 5, 24, 12 and 3 h, respectively. The addition of iron-carbon fillers to the acidification reactor was 200 mg/L while the best current density of electrolysis was 300 A/m2. The biodegradability was improved from 0.12 to 0.34 by micro-electrolysis. The whole treatment was found to be effective with removal of 96 % of the chemical oxygen demand (COD), 0.71 L/day of methane energy recovery. In addition, active chlorine production (15,720 mg/L) was obtained by electrolysis. The advantage of this hybrid process is that, through appropriate control of reaction conditions, effect from high concentration of salt on the treatment was avoided. Moreover, the process also produced the material needed in the production of oxidized starch while remaining emission-free and solved the problem of high process cost.

  3. Preparation and characterization of PbTi0{sub 3} ceramics modified by a natural mixture of rare earth oxides of xenotime

    Energy Technology Data Exchange (ETDEWEB)

    Baltazar-Rodrigues, Jair; Rodrigues Junior, Pedro; Cruz, Gerson K. da, E-mail: jbr@uepg.br [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil). Departamento de Fisica; Lente, Manuel H.; Eiras, Jose A. [Universidade Federal de Sao Carlos (UFSCar), SP (Brazil). Departamento de Fisica

    2014-01-15

    Lead titanate ceramics modified by xenotime (Xm) with nominal composition (Pb, Xm)TiO{sub 3}, Xm 10 or 15 mol %, were prepared by the conventional oxide mixture technique. Xenotime is a natural mineral consisting of a mixture of rare earth oxides. Thermal, structural and electric properties were investigated through differential and gravimetric thermal analysis, X-ray diffraction and dielectric measurements as a function of temperature. The results of both compositions revealed a higher density and free of cracks ceramic body, compared to pure PbTiO{sub 3} prepared by the same procedure. On the other hand, the structural characteristics and Curie temperature are nearly the same as those of pure PbTiO{sub 3}. The hysteresis loop measured at room temperature revealed a hard ferroelectric material with coercive field of 10.7 kV/cm and a remanent polarization of 0.2 μC/cm{sup 2}. These finding reveal a material with properties that highlight potential to be used as electronic devices that operate at high temperature and high frequencies. (author)

  4. Evaluation of a carbon paste electrode modified with Strontium substituted bismuth and titanium oxide nanoparticles in the toxic metal chromium (VI determination potentiometric method

    Directory of Open Access Journals (Sweden)

    Atefeh Badri

    2016-09-01

    Full Text Available Strontium substituted bismuth and titanium oxide nanoparticles with aurivillius morphology synthesized by chemical co-precipitation method and were characterized using XRD. The nanopartcles were used in the composition of the carbon paste to improve conductivity and transduction of chemical signal to electrical signal. A procedure for the determination of chromium is described based on pre-concentration of the dichromate anion at a carbon paste electrode modified. A novel potentiometric Cr6+carbon paste electrode incorporating Strontium substituted bismuth and titanium oxide nanoparticles (SSBTO. Ina acetate buffer solution of pH 5, the sensor displays a rapid and linear response for Cr6+ over the concentration range 1.0×10-5 to 1.0×10-1mol L-1 M with an anionic slope of 54.8± 0.2 mV decade ’ and a detection limit of the order of0.002 /µg ml ‘. The sensor is used for determination of Cr6+ by direct monitoring of Cr6+.The average recoveries of Cr6+at concentration levels of 0.5~40 pg/ml ’is 98.3. The electrode has a short response time (<6s and can be used for at least twenty days without any considerable divergence in potentials and the working pH range was 4.5-6.5. The proposed electrode was successfully used as an indicator for potentiometric determination of Cr6+in water sample.

  5. Study on non-linear equilibrium, kinetics and thermodynamic of deltamethrin removal in aqueous solution using modified magnetic iron oxide nanoparticles.

    Science.gov (United States)

    Ghafari, Bahareh; Moniri, Elham; Panahi, Homayon Ahmad; Karbassi, Abdolreza; Najafpour, Shaban

    2017-08-01

    The purpose of modification of magnetic iron oxide nanoparticles is an eco-friendly, emerging and economical method for removing deltamethrin in the aqueous solution and wastewater effluents when compared with other adsorbent methods. Modified magnetic iron oxide nanoparticles were synthesized by co-precipitation and then coupled with 3-hydroxytyraminium chloride. The nano-sorbent was characterized by thermogravimetric analysis, elemental analysis, transmission electron microscopy, scanning electron microscope, Fourier transform infrared spectroscopy, zero point charge and surface area determination. Batch studies were conducted and adsorption equilibrium, kinetic and thermodynamic non-linear models were carried out. The resulting equilibrium data were tested with Langmuir and Freundlich non-linear isotherm models, and the results showed that the Langmuir isotherm fitted the data well. Kinetic studies were done with different initial deltamethrin concentrations, adsorbent dosage and temperature, and the data were assimilated with pseudo-first order, pseudo-second order and intra-particle diffusion kinetic equations, and it was found that the studied nano-sorbent processes followed the pseudo-second order kinetic equation. Thermodynamic analysis was also carried out to estimate the changes in free energy (ΔG 0 ), enthalpy (ΔH 0 ), and entropy (ΔS 0 ). The thermodynamic parameters revealed that the adsorption of deltamethrin into the nano-sorbent was spontaneous, feasible and showed an endothermic process.

  6. Dopamine and uric acid electrochemical sensor based on a glassy carbon electrode modified with cubic Pd and reduced graphene oxide nanocomposite.

    Science.gov (United States)

    Wang, Jin; Yang, Beibei; Zhong, Jiatai; Yan, Bo; Zhang, Ke; Zhai, Chunyang; Shiraishi, Yukihide; Du, Yukou; Yang, Ping

    2017-07-01

    A cubic Pd and reduced graphene oxide modified glassy carbon electrode (Pd/RGO/GCE) was fabricated to simultaneously detect dopamine (DA) and uric acid (UA) by cyclic voltammetry (CV) and different pulse voltammetry (DPV) methods. Compared with Pd/GCE and RGO/GCE, the Pd/RGO/GCE exhibited excellent electrochemical activity in electrocatalytic behaviors. Performing the Pd/RGO/GCE in CV measurement, the well-defined oxidation peak potentials separation between DA and UA reached to 145mV. By using the differential pulse voltammetry (DPV) technique, the calibration curves for DA and UA were found linear with the concentration range of 0.45-421μM and 6-469.5μM and the detection limit (S/N =3) were calculated to be 0.18μM and 1.6μM, respectively. Furthermore, the Pd/RGO/GCE displayed high selectivity when it was applied into the determination of DA and UA even though in presence of high concentration of interferents. Additionally, the prepared electrochemical sensor of Pd/RGO/GCE demonstrated a practical feasibility in rat urine and serum samples determination. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Effects of Modified Iron Oxide Nanoparticles on the Thermal and Dynamic Mechanical Properties of Cellulose Poly(vinyl alcohol Blend Films

    Directory of Open Access Journals (Sweden)

    Mehdi Roohani

    2015-11-01

    Full Text Available This study was designed to investigate the effect of modified iron oxide nanoparticles (MINP and cellulose nanocrystals (NCC on magnetic, thermal and dynamic-mechanical properties of poly(vinyl alcohol based nanocomposites. Fe3O4 nanoparticles have been synthesized using a chemical co-precipitation route. Nanocomposite films were developed by solvent casting method and their properties were characterized by vibrating sample magnetometer (VSM, differential scanning calorimetry (DSC and dynamic mechanical analysis (DMA. DSC results found that with incorporation of nanoparticles, the glass transition temperature increase slightly to higher temperatures; however, the degree of crystallinity and the values of the melting temperature are found to decrease. Dynamic mechanical analysis revealed that, at the elevated temperatures, improvement of mechanical properties due to the presence of nanoparticles was even more noticeable. Addition of nanoparticles resulted in increased thermal stability of PVA due to the reduction in mobility of matrix molecules by strong hydrogen bonds between nanocomposite components. Results indicated that, MINP and NCC have synergistic effect on improving of poly(vinyl alcohol properties. The VSM findings showed that the saturation magnetization of iron oxide nanoparticles reduced after modification. This can be attributed to formation of hydroxyapatite on nanoparticles surface. The saturation magnetization (Ms of PVA- MINP films was higher than PVA-MINP- NCC film. This result probably is related to more amount of magnetic nanoparticles in PVA-MINP films.

  8. The Association between Diabetic Retinopathy and Levels of Ischemia-Modified Albumin, Total Thiol, Total Antioxidant Capacity, and Total Oxidative Stress in Serum and Aqueous Humor

    Directory of Open Access Journals (Sweden)

    Kadir Kirboga

    2014-01-01

    Full Text Available Purpose. To investigate the oxidant and antioxidant status of patients with type 2 diabetes mellitus and nonproliferative diabetic retinopathy (DRP. Methods. Forty-four patients who had cataract surgery were enrolled in the study. We included 22 patients with DRP in one group and 22 patients in the control group. Samples of aqueous humor and serum were taken from all patients. Serum and aqueous ischemia-modified albumin (IMA, total thiol, total antioxidant capacity (TAC, and total oxidative stress (TOS levels were compared in two groups. Results. Median serum IMA levels were 44.80 absorbance units in the DRP group and 40.15 absorbance units in the control group (P=0.031. Median serum total thiol levels in the DRP group were significantly less than those in the control group (3051.13 and 3910.12, resp., P=0.004. Mean TOS levels in the serum were 2.93 ± 0.19 in the DRP group and 2.61 ± 0.26 in the control group (P=0.039. The differences in mean total thiol, TAC, and TOS levels in the aqueous humor and mean TAC levels in the serum were not statistically significant. Conclusion. IMA, total thiol, and TOS levels in the serum might be useful markers in monitoring the risk of DRP development.

  9. Highly sensitive and wide-range nonenzymatic disposable glucose sensor based on a screen printed carbon electrode modified with reduced graphene oxide and Pd-CuO nanoparticles

    International Nuclear Information System (INIS)

    Dhara, Keerthy; Thiagarajan, Ramachandran; Thekkedath, Gopalakrishnan Satheesh Babu; Nair, Bipin G.

    2015-01-01

    A nanocomposite consisting of reduced graphene oxide decorated with palladium-copper oxide nanoparticles (Pd-CuO/rGO) was synthesized by single-step chemical reduction. The morphology and crystal structure of the nanocomposite were characterized by field-emission scanning electron microscopy, high resolution transmission electron microscopy and X-ray diffraction analysis. A 3-electrode system was fabricated by screen printing technology and the Pd-CuO/rGO nanocomposite was drop cast on the carbon working electrode. The catalytic activity towards glucose in 0.2 M NaOH solutions was analyzed by linear sweep voltammetry and amperometry. The steady state current obtained at a constant potential of +0.6 V (vs. Ag/AgCl) showed the modified electrode to possess a wide analytical range (6 μM to 22 mM), a rather low limit of detection (30 nM), excellent sensitivity (3355 μA∙mM −1 ∙cm −2 ) and good selectivity over commonly interfering species and other sugars including fructose, sucrose and lactose. The sensor was successfully employed to the determination of glucose in blood serum. (author)

  10. High efficiency of isopropanol combustion over cobalt oxides modified ZSM-5 zeolite membrane catalysts on paper-like stainless steel fibers

    Science.gov (United States)

    Wang, Tao; Zhang, Huiping; Yan, Ying

    2017-07-01

    Catalytic performances of isopropanol combustion and bed pressure drop in structured fixed bed reactor composed of cobalt oxides modified ZSM-5 zeolite membrane catalysts on paper-like stainless steel fibers (Co/ZSM-5/PSSF) and traditional granular ZSM-5 zeolites catalysts were investigated in this paper. Both of the catalyst samples were fabricated by wetness impregnation method and were characterized via X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectrometer (EDS) mapping and the N2 adsorption/desorption isotherm analyses. The result of EDS mapping revealed that cobalt oxides dispersed well on ZSM-5/PSSF. The Co/ZSM-5/PSSF catalyst display superior catalytic activity to granular Co/ZSM-5 catalyst, 50% and 90% isopropanol conversion temperatures over Co/ZSM-5/PSSF reduced 107 °C and 51 °C, respectively, compared with those over granular Co/ZSM-5 catalysts. The apparent activation energy for isopropanol combustion over Co/ZSM-5/PSSF (90 kJ/mol) was much lower than that over granular Co/ZSM-5 (134 kJ/mol). When the face velocity increased to 14.9 cm/s, the bed pressure drop of reactor filled with only Co/ZSM-5/PSSF catalysts was 9.5% of that of reactor filled with only granular Co/ZSM-5 catalysts. The ZSM-5 zeolite membrane on paper-like stainless steel fibers support provide good dispersion for cobalt oxides and Co/ZSM-5/PSSF show superior catalytic efficiency of isopropanol combustion and produced lower bed pressure drop in reactor compared with granular ZSM-5 zeolites. Co/ZSM-5/PSSF composite catalyst show superior catalytic activity for isopropanol combustion and produced lower bed pressure drop compared with traditional granular Co/ZSM-5.

  11. SiO2-coated magnetic graphene oxide modified with polypyrrole-polythiophene: A novel and efficient nanocomposite for solid phase extraction of trace amounts of heavy metals.

    Science.gov (United States)

    Molaei, Karam; Bagheri, Hasan; Asgharinezhad, Ali Akbar; Ebrahimzadeh, Homeira; Shamsipur, Mojtaba

    2017-05-15

    The synthesis of a novel nanocomposite comprised of SiO 2 -coated magnetic graphene oxide modified with a pyrrole-thiophene (mGO/SiO 2 @coPPy-Th) copolymer is reported in the present work. The nanocomposite was applied for the fast magnetic solid phase extraction (MSPE) of trace levels of copper, lead, chromium, zinc and cadmium from water and agricultural samples. The nanocomposite was prepared in three steps: (1) decoration of graphene oxide sheets with magnetite nanoparticles thorough a facile one-step chemical reaction strategy; (2) chemical grafting by a silica layer to obtain high stability in acidic solutions; and (3) surface modification by coPPy-Th via simultaneous oxidation polymerization of pyrrole and thiophene in the presence of mGO/SiO 2 composite. The nanocomposite was subsequently characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD) and vibrating sample magnetometry (VSM) techniques. Several important experimental variables that could affect MSPE performance, including the pH of the sample, sorption time, sorbent dosage, eluent type and its concentration, eluent volume and elution time, were investigated and optimized. Under optimal conditions, the limits of detection for the target heavy metals ranged from 0.15 to 0.65μgL -1 . The maximum sorption capacity of the mGO/SiO 2 @coPPy-Th nanocomposite was 201, 230, 125, 98 and 80mgg -1 for Cu(II), Pb(II), Zn(II), Cr(III) and Cd(II), respectively. Finally, the feasibility of the proposed method was investigated for the extraction and determination of the target metals from real matrices. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. SIGNIFICANCE OF ISCHEMIA-MODIFIED ALBUMIN AS A SIMPLE MEASURE OF OXIDATIVE STRESS AND ITS DISCRIMINATORY ABILITY IN DIABETIC RETINOPATHY: Literature Review and Meta-Analysis.

    Science.gov (United States)

    Seshadri Reddy, Varikasuvu; Sethi, Sumita; Gupta, Navdeep; Agrawal, Poonam; Chander Siwach, Ram

    2016-06-01

    Oxidative stress (OXS) plays critical role in the development of diabetic retinopathy (DRP). Increased concentrations of serum ischemia-modified albumin (IMA) have been demonstrated as a novel and inexpensive measure of oxidative stress. Although few pilot studies have reported increased IMA in DRP, the available literature is limited to comprehensively describe the potential significance of IMA in predicting DRP. The authors performed a meta-analysis to investigate IMA in DRP compared with control and diabetes mellitus subjects. The authors also performed a meta-analysis of area under curve for IMA. PubMed (Medline), Embase, Scopus, Web of Science, Science Direct, Springer Link, and Google Scholar databases were searched for relevant studies in serum IMA in DRP. The authors obtained five observational studies. Meta-analysis was performed using Review Manager 5.3 and MEDCALC 15.8 software to present the pooled-overall effect size as standardized mean difference and overall area under curve value of IMA. Random-effects meta-analysis indicated a significant increase in serum IMA in patients with DRP compared with control (standardized mean difference = 2.48, P diabetes mellitus groups (standardized mean difference = 1.43, P predict the development of DRP (area under curve = 0.86, P < 0.001). Serum IMA may be useful as a simple marker in monitoring of oxidative stress status in DRP and showed significant discriminatory ability in DRP. Future comparative studies in large are needed to further investigate IMA in different types of DRP; proliferative and nonproliferative.

  13. Highly sensitive amperometric sensing of nitrite utilizing bulk-modified MnO2 decorated Graphene oxide nanocomposite screen-printed electrodes

    International Nuclear Information System (INIS)

    Jaiswal, Nandita; Tiwari, Ida; Foster, Christopher W.; Banks, Craig E.

    2017-01-01

    A screen-printed amperometric sensor based on a carbon ink bulk-modified with MnO 2 decorated graphene oxide (MnO 2 /GO-SPE) nanocomposite was investigated for its ability to serve as a sensor towards nitrite. The composite was prepared by simple ultrasonication and reflux methodology and was characterized by FT-IR spectroscopy, transmission electron microscopy, scanning electron microscopy, Raman spectroscopy, atomic force microscopy and electrochemically using cyclic voltammetry, chronoamperometry and differential pulse voltammetry techniques. The MnO 2 /GO-SPE was found to exhibit an electro-catalytic activity for the electrochemical oxidation of nitrite in 0.1 M phosphate buffer solution (pH 7.4). The electrochemical oxidation of nitrite occurs at +0.55 V (Vs. Ag/AgCl) with a limit of detection (3σ) found to be 0.09 μM and with two linear ranges of 0.1 μM to 1 μM and 1 μM to 1000 μM with sensitivities of 1.25 μAμM −1 cm −2 and 0.005 μAμM −1 cm −2 respectively. Furthermore, the MnO 2 /GO-SPE showed an excellent anti-interference ability towards a range of commonly encountered electroactive species and metal ions. Additionally, the fabricated MnO 2 /GO-SPE nitrite sensor presented an excellent selectivity, reproducibility and stability. The presented study widens the scope of applications of graphene-based nanocomposite materials for on-site monitoring of nitrite.

  14. Magnetic graphene oxide modified with choline chloride-based deep eutectic solvent for the solid-phase extraction of protein

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Yanhua; Wang, Yuzhi, E-mail: wyzss@hnu.edu.cn; Pan, Qi; Wang, Ying; Ding, Xueqin; Xu, Kaijia; Li, Na; Wen, Qian

    2015-06-02

    Highlights: • A strategy for extraction of protein based on DES-coated magnetic graphene oxide. • The deep eutectic solvents were based on choline chloride. • Bovine serum albumin was used as the analyte. • The material prepared works for the acidic but not the basic or the neutral proteins. - Abstract: Four kinds of green deep eutectic solvents (DESs) based on choline chloride (ChCl) have been synthesized and coated on the surface of magnetic graphene oxide (Fe{sub 3}O{sub 4}@GO) to form Fe{sub 3}O{sub 4}@GO-DES for the magnetic solid-phase extraction of protein. X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Fourier transform infrared spectrometry (FTIR), field emission scanning electron microscopy (FESEM) and thermal gravimetric analysis (TGA) were employed to characterize Fe{sub 3}O{sub 4}@GO-DES, and the results indicated the successful preparation of Fe{sub 3}O{sub 4}@GO-DES. The UV–vis spectrophotometer was used to measure the concentration of protein after extraction. Single factor experiments proved that the extraction amount was influenced by the types of DESs, solution temperature, solution ionic strength, extraction time, protein concentration and the amount of Fe{sub 3}O{sub 4}@GO-DES. Comparison of Fe{sub 3}O{sub 4}@GO and Fe{sub 3}O{sub 4}@GO-DES was carried out by extracting bovine serum albumin, ovalbumin, bovine hemoglobin and lysozyme. The experimental results showed that the proposed Fe{sub 3}O{sub 4}@GO-DES performs better than Fe{sub 3}O{sub 4}@GO in the extraction of acidic protein. Desorption of protein was carried out by eluting the solid extractant with 0.005 mol L{sup −1} Na{sub 2}HPO{sub 4} contained 1 mol L{sup −1} NaCl. The obtained elution efficiency was about 90.9%. Attributed to the convenient magnetic separation, the solid extractant could be easily recycled.

  15. A Functional Iron Oxide Nanoparticles Modified with PLA-PEG-DG as Tumor-Targeted MRI Contrast Agent.

    Science.gov (United States)

    Xiong, Fei; Hu, Ke; Yu, Haoli; Zhou, Lijun; Song, Lina; Zhang, Yu; Shan, Xiuhong; Liu, Jianping; Gu, Ning

    2017-08-01

    Tumor targeting could greatly promote the performance of magnetic nanomaterials as MRI (Magnetic Resonance Imaging) agent for tumor diagnosis. Herein, we reported a novel magnetic nanoparticle modified with PLA (poly lactic acid)-PEG (polyethylene glycol)-DG (D-glucosamine) as Tumor-targeted MRI Contrast Agent. In this work, we took use of the D-glucose passive targeting on tumor cells, combining it on PLA-PEG through amide reaction, and then wrapped the PLA-PEG-DG up to the Fe 3 O 4 @OA NPs. The stability and anti phagocytosis of Fe 3 O 4 @OA@PLA-PEG-DG was tested in vitro; the MRI efficiency and toxicity was also detected in vivo. These functional magnetic nanoparticles demonstrated good biocompatibility and stability both in vitro and in vivo. Cell experiments showed that Fe 3 O 4 @OA@PLA-PEG-DG nanoparticles exist good anti phagocytosis and high targetability. In vivo MRI images showed that the contrast effect of Fe 3 O 4 @OA@PLA-PEG-DG nanoparticles prevailed over the commercial non tumor-targeting magnetic nanomaterials MRI agent at a relatively low dose. The DG can validly enhance the tumor-targetting effect of Fe 3 O 4 @OA@PLA-PEG nanoparticle. Maybe MRI agents with DG can hold promise as tumor-targetting development in the future.

  16. Ab initio study on the noncovalent adsorption of camptothecin anticancer drug onto graphene, defect modified graphene and graphene oxide.

    Science.gov (United States)

    Saikia, Nabanita; Deka, Ramesh C

    2013-09-01

    The application of graphene and related nanomaterials like boron nitride (BN) nanosheets, BN-graphene hybrid nanomaterials, and graphene oxide (GO) for adsorption of anticancer chemotherapeutic camptothecin (CPT) along with the effect on electronic properties prior to functionalization and after functionalization has been reported using density functional theory (DFT) calculations. The inclusion of dispersion correction to DFT is instrumental in accounting for van der Waals π-π stacking between CPT and the nanomaterial. The adsorption of CPT exhibits significant strain within the nanosheets and noncovalent adsorption of CPT is thermodynamically favoured onto the nanosheets. In case of GO, surface incorporation of functional groups result in significant crumpling along the basal plane and the interaction is basically mediated by H-bonding rather than π-π stacking. Docking studies predict the plausible binding of CPT, CPT functionalized graphene and GO with topoisomerase I (top 1) signifying that CPT interacts through π stacking with AT and GC base pairs of DNA and in presence of nano support, DNA bases preferentially gets bound to the basal plane of graphene and GO rather than the edges. At a theoretical level of understanding, our studies point out the noncovalent interaction of CPT with graphene based nanomaterials and GO for loading and delivery of anticancer chemotherapeutic along with active binding to Top1 protein.

  17. THE EFFECT OF THE TYPE OF ADMIXTURE ON THE PROPERTIES OF POLYACRYLONITRILE MEMBRANES MODIFIED WITH NANOTUBES, GRAPHENE OXIDE AND GRAPHENE

    Directory of Open Access Journals (Sweden)

    Beata Fryczkowska

    2017-09-01

    Full Text Available This paper presents the results of research on the production of composite polyacrylonitrile (PAN membranes with nanotubes (MWCNT, graphene (RG and graphene oxide (GO addition. All of the specified additions differ diametrically in terms of properties, starting from the spatial structure of the particles, up to the chemical properties. Membranes were obtained using phase inversion method from a solution of N,N-dimethylformamide (DMF. Subsequently, the impact of the nano-addition on the transport and separation properties of the membranes were investigated using Millipore AMICON ultrafiltration kit. Membranes with graphene addition (PAN/RG are characterized by the best transport properties and the highest specific permeate flux values in the range of ~913÷1006 [dm3/m2×h] for working pressure of 2.0 MPa. To test the separation properties, electroplating waste water generated in one of the Silesian galvanizing plants was used. The qualitative and quantitative composition of the waste water was tested by UV-Vis spectrophotometer (HACH and absorption atomic spectrometry (AAS. The ultrafiltration process carried out on composite membranes allows for the complete removal of phosphate ions and ~88÷94% of iron from the waste water. The rejection coefficient of the remaining metals is high: ~ 35 ÷ 85% for copper and ~ 17 ÷ 100% for cadmium.

  18. Decolourisation of dye solutions by oxidation with H2O2 in the presence of modified activated carbons

    International Nuclear Information System (INIS)

    Santos, V.P.; Pereira, M.F.R.; Faria, P.C.C.; Orfao, J.J.M.

    2009-01-01

    The decolourisation of dye solutions by oxidation with H 2 O 2 , using activated carbon as catalyst, is studied. For this purpose, three different samples, mainly differing in the respective surface chemistries, were prepared and characterized. Moreover, this work involved three pH levels, corresponding to acid, neutral and alkaline solutions, and six dyes belonging to several classes. The catalytic decolourisation tests were performed in a laboratorial batch reactor. Adsorption on activated carbon and non-catalytic peroxidation kinetic experiments were also carried out in the same reactor, in order to compare the efficiencies of the three processes. The non-catalytic reaction is usually inefficient and, typically, adsorption presents a low level of decolourisation. In these cases, the combination of activated carbon with hydrogen peroxide may significantly enhance the process, since the activated carbon catalyses the decomposition of H 2 O 2 into hydroxyl radicals, which are very reactive. Based on the experiments with the different activated carbon samples, which have similar physical properties, it is proved that the surface chemistry of the catalyst plays a key role, being the basic sample the most active. This is discussed considering the involvement of the free electrons on the graphene basal planes of activated carbon as active centres for the catalytic reaction. Additionally, it is shown that the decolourisation is enhanced at high pH values, and a possible explanation for this observation, based on the proposed mechanism, is given

  19. Adsorption and removal of bisphenol A from aqueous solution by p-phenylenediamine modified magnetic graphene oxide

    Directory of Open Access Journals (Sweden)

    Tang Xiaosheng

    2017-01-01

    Full Text Available p-Phenylenediamine functionalized magnetic graphene oxide nanocomposites (PPD-MGO were prepared and utilized in the adsorption and removal of bisphenol A in aqueous solution. The novel nanomaterials were characterized by transmission electron microscopy (TEM, Fourier infrared spectrometry (FT-IR and vibrating sample magnetometer (VSM. The factors affected the adsorption of bisphenol A including adsorption time, temperature and pH of solution, adsorption kinetics and isotherms were all investigated. The results showed that PPD-MGO nanomaterial exhibited good adsorption ability for bisphenol A and good resuability. The maximum adsorption capacity reached 155.0 mg g-1 at 45°C and pH 7. The removal rate was 99.2 % after three times of adsorption with new nanomaterials. After five cycles adsorption, the adsorption capacity of PPD-MGO remained at 94.0 %. The adsorption of bisphenol A was found that fitted pseudo second order kinetics equations and the Freundlich adsorption model. The experimental results showed the PPD-MGO nanomaterial had a good adsorption ability to remove organic compounds in aqueous solution.

  20. Decolourisation of dye solutions by oxidation with H(2)O(2) in the presence of modified activated carbons.

    Science.gov (United States)

    Santos, V P; Pereira, M F R; Faria, P C C; Orfão, J J M

    2009-03-15

    The decolourisation of dye solutions by oxidation with H(2)O(2), using activated carbon as catalyst, is studied. For this purpose, three different samples, mainly differing in the respective surface chemistries, were prepared and characterized. Moreover, this work involved three pH levels, corresponding to acid, neutral and alkaline solutions, and six dyes belonging to several classes. The catalytic decolourisation tests were performed in a laboratorial batch reactor. Adsorption on activated carbon and non-catalytic peroxidation kinetic experiments were also carried out in the same reactor, in order to compare the efficiencies of the three processes. The non-catalytic reaction is usually inefficient and, typically, adsorption presents a low level of decolourisation. In these cases, the combination of activated carbon with hydrogen peroxide may significantly enhance the process, since the activated carbon catalyses the decomposition of H(2)O(2) into hydroxyl radicals, which are very reactive. Based on the experiments with the different activated carbon samples, which have similar physical properties, it is proved that the surface chemistry of the catalyst plays a key role, being the basic sample the most active. This is discussed considering the involvement of the free electrons on the graphene basal planes of activated carbon as active centres for the catalytic reaction. Additionally, it is shown that the decolourisation is enhanced at high pH values, and a possible explanation for this observation, based on the proposed mechanism, is given.

  1. Influence of Pt nanoparticles modified by La and Ce oxides on catalytic dehydrocyclization of n-alkanes

    Directory of Open Access Journals (Sweden)

    A.H. Samia

    2015-06-01

    Full Text Available Catalytic reforming accounts for a large share of the world’s gasoline production, it is the most important source of aromatics for the petrochemical industry. In addition, reforming of hydrocarbon on the dual-function catalysts has been found to form fundamentally different products in hydrogen diluents. Typical catalysts employed for this reforming process are Pt/Al2O3 and Pt-M/Al2O3, M being the promoter. These solids are characterized by both acid and metal functions which catalyze dehydrocyclization, dehydrogenation, isomerization and cracking processes. In this regard, information about cerium and lanthanum, as promoters, is hardly revealed. The present work aims to study the performance of Pt/Al2O3 catalysts modified by lanthanum or cerium during the conversion of cyclohexane, n-hexane and n-heptane. Catalytic activities of the prepared catalysts were tested using a micro catalytic pulse technique. Physicochemical characterization of the solid catalysts such as, surface area (SBET, Fourier transform infrared (FTIR, differential scanning calorimetry (DSC, thermogravimetric analysis (TGA, hydrogen-temperature programed reduction (H2-TPR, hydrogen-temperature-programed desorption (H2-TPD, CO2-TPD, NH3-TPD, high resolution transmission electron microscopy (HRTEM and X-ray diffraction (XRD were depicted. Results indicated clearly that Pt/Al2O3 catalyst is selective toward dehydrogenation to benzene which could be explained as due to the decrease in the active acid sites and the comparative segregation of the alumina support especially at 3% load of CeO. The presence of La2O3 in the Pt/Al2O3 catalyst promotes aromatization of n-hexane and n-heptane, also the dehydrocyclization of n-hexane is more difficult than that of n-heptane. Thus, modification of the Pt/Al2O3 catalyst by La, resulted in a more active and selective reforming catalyst.

  2. Evaluation of tetraethoxysilane (TEOS) sol–gel coatings, modified with green synthesized zinc oxide nanoparticles for combating microfouling

    Energy Technology Data Exchange (ETDEWEB)

    Krupa, A. Nithya Deva; Vimala, R., E-mail: vimala.r@vit.ac.in

    2016-04-01

    Green synthesis of zinc oxide nanoparticles (ZnO-NPs) is gaining importance as an eco-friendly alternative to conventional methods due to its enormous applications. The present work reports the synthesis of ZnO-NPs using the endosperm of Cocos nucifera (coconut water) and the bio-molecules responsible for nanoparticle formation have been identified. The synthesized nanoparticles were characterized using UV–Visible spectroscopy (UV–Vis), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Zeta potential measurement. The results obtained reveal that the synthesized nanoparticles are moderately stable with the size ranging from 20 to 80 nm. The bactericidal effect of the nanoparticles was proved by well diffusion assay and determination of minimum inhibitory concentration (MIC) against marine biofilm forming bacteria. Further the green synthesized ZnO-NPs were doped with TEOS sol–gels (TESGs) in order to assess their antimicrofouling capability. Different volumes of liquid sol–gels were coated on to 96-well microtitre plate and cured under various conditions. The optimum curing conditions were found to be temperature 60 °C, time 72 h and volume 200 μl. Antiadhesion test of the undoped (SG) and ZnO-NP doped TEOS sol–gel (ZNSG) coatings were evaluated using marine biofilm forming bacteria. ZNSG coatings exhibited highest biofilm inhibition (89.2%) represented by lowest OD value against Pseudomonasotitidis strain NV1. - Highlights: • The study reports low cost, and simple procedure for the synthesis of ZnO-NPs using coconut water. • XRD result shows the high crystalline nature of the synthesized ZnO-NPs. • TEM and zeta potential distribution confirms the nanostructure, stability of the synthesized ZnO-NPs. • ZnO-NPs doped with TEOS sol¬-gels (TESGs) exhibited excellent antimicrofouling activity.

  3. Multifunctional nanosheets based on hyaluronic acid modified graphene oxide for tumor-targeting chemo-photothermal therapy

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Lin; Feng, Qianhua; Wang, Yating; Zhang, Huijuan; Jiang, Guixiang; Yang, Xiaomin; Ren, Junxiao; Zhu, Xiali; Shi, Yuyang; Zhang, Zhenzhong, E-mail: zhangzz-pharm@163.com [Zhengzhou University, School of Pharmaceutical Sciences (China)

    2015-03-15

    Graphene oxide (GO) with strong optical absorption in the near-infrared (NIR) region has shown great potential both in photothermal therapy and drug delivery. In this work, hyaluronic acid (HA)-functionalized GO (HA-GO) was successfully synthesized and controlled loading of mitoxantrone (MIT) onto HA-GO via π–π stacking interaction was investigated. The results revealed that drug-loaded nanosheets with high loading efficiency of 45 wt% exhibited pH-sensitive responses to tumor environment. Owing to the receptor-mediated endocytosis, cellular uptake analysis of HA-GO showed enhanced internalization. In vivo optical imaging test demonstrated that HA-GO nanosheets could enhance the targeting ability and residence time in tumor site. Moreover, the anti-tumor activity of free MIT, MIT/GO, and MIT/HA-GO in combination with NIR laser was investigated using human MCF-7 cells. In vitro cytotoxicity study revealed that HA-GO could stand as a biocompatible nanocarrier and MIT/HA-GO demonstrated remarkably higher toxicity than free MIT and MIT/GO, with IC{sub 50} of 0.79 µg ml{sup −1}. Tumor cell-killing potency was enhanced when MIT/HA-GO were combined with NIR irradiation, and the IC{sub 50} of MIT/HA-GO plus laser irradiation was 0.38 µg ml{sup −1}. In vivo, MIT/HA-GO plus NIR laser irradiation with the tumor growth inhibition of 93.52 % displayed greater anti-tumor effect compared with free MIT and MIT/GO with or without laser irradiation. Therefore, the MIT/HA-GO nanosheets may potentially be useful for further development of synergistic cancer therapy.

  4. Amine-modified magnetic iron oxide nanoparticle as a promising carrier for application in bio self-healing concrete.

    Science.gov (United States)

    Seifan, Mostafa; Ebrahiminezhad, Alireza; Ghasemi, Younes; Samani, Ali Khajeh; Berenjian, Aydin

    2018-01-01

    Self-healing mechanisms are a promising solution to address the concrete cracking issue. Among the investigated self-healing strategies, the biotechnological approach is distinguished itself by inducing the most compatible material with concrete composition. In this method, the potent bacteria and nutrients are incorporated into the concrete matrix. Once cracking occurs, the bacteria will be activated, and the induced CaCO 3 crystals will seal the concrete cracks. However, the effectiveness of a bio self-healing concrete strictly depends on the viability of bacteria. Therefore, it is required to protect the bacteria from the resulted shear forces caused by mixing and drying shrinkage of concrete. Due to the positive effects on mechanical properties and the high compatibility of metallic nanoparticles with concrete composition, for the first time, we propose 3-aminopropyltriethoxy silane-coated iron oxide nanoparticles (APTES-coated IONs) as a biocompatible carrier for Bacillus species. This study was aimed to investigate the effect of APTES-coated IONs on the bacterial viability and CaCO 3 yield for future application in the concrete structures. The APTES-coated IONs were successfully synthesized and characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results show that the presence of 100 μg/mL APTES-coated IONs could increase the bacterial viability. It was also found that the CaCO 3 -specific yield was significantly affected in the presence of APTES-coated IONs. The highest CaCO 3 -specific yield was achieved when the cells were decorated with 50 μg/mL of APTES-coated IONs. This study provides new insights for the application of APTES-coated IONs in designing bio self-healing strategies.

  5. Multifunctional nanosheets based on hyaluronic acid modified graphene oxide for tumor-targeting chemo-photothermal therapy

    Science.gov (United States)

    Hou, Lin; Feng, Qianhua; Wang, Yating; Zhang, Huijuan; Jiang, Guixiang; Yang, Xiaomin; Ren, Junxiao; Zhu, Xiali; Shi, Yuyang; Zhang, Zhenzhong

    2015-03-01

    Graphene oxide (GO) with strong optical absorption in the near-infrared (NIR) region has shown great potential both in photothermal therapy and drug delivery. In this work, hyaluronic acid (HA)-functionalized GO (HA-GO) was successfully synthesized and controlled loading of mitoxantrone (MIT) onto HA-GO via π- π stacking interaction was investigated. The results revealed that drug-loaded nanosheets with high loading efficiency of 45 wt% exhibited pH-sensitive responses to tumor environment. Owing to the receptor-mediated endocytosis, cellular uptake analysis of HA-GO showed enhanced internalization. In vivo optical imaging test demonstrated that HA-GO nanosheets could enhance the targeting ability and residence time in tumor site. Moreover, the anti-tumor activity of free MIT, MIT/GO, and MIT/HA-GO in combination with NIR laser was investigated using human MCF-7 cells. In vitro cytotoxicity study revealed that HA-GO could stand as a biocompatible nanocarrier and MIT/HA-GO demonstrated remarkably higher toxicity than free MIT and MIT/GO, with IC50 of 0.79 µg ml-1. Tumor cell-killing potency was enhanced when MIT/HA-GO were combined with NIR irradiation, and the IC50 of MIT/HA-GO plus laser irradiation was 0.38 µg ml-1. In vivo, MIT/HA-GO plus NIR laser irradiation with the tumor growth inhibition of 93.52 % displayed greater anti-tumor effect compared with free MIT and MIT/GO with or without laser irradiation. Therefore, the MIT/HA-GO nanosheets may potentially be useful for further development of synergistic cancer therapy.

  6. Nitric oxide synthase (NOS inhibition during porcine in vitro maturation modifies oocyte protein S-nitrosylation and in vitro fertilization.

    Directory of Open Access Journals (Sweden)

    Jon Romero-Aguirregomezcorta

    Full Text Available Nitric oxide (NO is a molecule involved in many reproductive processes. Its importance during oocyte in vitro maturation (IVM has been demonstrated in various species although sometimes with contradictory results. The objective of this study was to determine the effect of NO during IVM of cumulus oocyte complexes and its subsequent impact on gamete interaction in porcine species. For this purpose, IVM media were supplemented with three NOS inhibitors: NG-nitro-L-arginine methyl ester (L-NAME, NG-monomethyl-L-arginine (L-NMMA and aminoguanidine (AG. A NO donor, S-nitrosoglutathione (GSNO, was also used. The effects on the cumulus cell expansion, meiotic resumption, zona pellucida digestion time (ZPdt and, finally, on in vitro fertilization (IVF parameters were evaluated. The oocyte S-nitrosoproteins were also studied by in situ nitrosylation. The results showed that after 42 h of IVM, AG, L-NAME and L-NMMA had an inhibitory effect on cumulus cell expansion. Meiotic resumption was suppressed only when AG was added, with 78.7% of the oocytes arrested at the germinal vesicle state (P<0.05. Supplementation of the IVM medium with NOS inhibitors or NO donor did not enhance the efficiency of IVF, but revealed the importance of NO in maturation and subsequent fertilization. Furthermore, protein S-nitrosylation is reported for the first time as a pathway through which NO exerts its effect on porcine IVM; therefore, it would be important to determine which proteins are nitrosylated in the oocyte and their functions, in order to throw light on the mechanism of action of NO in oocyte maturation and subsequent fertilization.

  7. Interfacial Modifiers

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Ina; French, Roger H.

    2018-03-19

    Our project objective in the first and only Budget Period was to demonstrate the potential of nm-scale organofunctional silane coatings as a method of extending the lifetime of PV materials and devices. Specifically, the target was to double the lifetime performance of a laminated Cu(In,Ga)Se2 (CIGS) cell under real-world and accelerated aging exposure conditions. Key findings are that modification of aluminum-doped zinc oxide (AZO) films (materials used as transparent conductive oxide (TCO) top contacts) resulted in decreased degradation of optical and electrical properties under damp heat (DH) exposure compared to un-modified AZO. The most significant finding is that modification of the AZO top contact of full CIGS devices resulted in significantly improved properties under DH exposure compared to un-modified devices, by a factor of 4 after 1000 h. Results of this one-year project have demonstrated that surface functionalization is a viable pathway for extending the lifetime of state-of-the-art CIGS devices.

  8. Improvements of photocurrent by using modified SiO(2) in the poly(ether urethane)/poly(ethylene oxide) polymer electrolyte for all-solid-state dye-sensitized solar cells.

    Science.gov (United States)

    Zhou, Yanfang; Xiang, Wanchun; Chen, Shen; Fang, Shibi; Zhou, Xiaowen; Zhang, Jingbo; Lin, Yuan

    2009-07-14

    Nanocomposite polymer electrolytes containing poly(ether urethane) (PEUR)/poly(ethylene oxide) (PEO)/modified SiO(2) were prepared for all-solid-state dye-sensitized solar cells with a high efficiency of 4.86% and an active area of 0.25 cm(2) under AM1.5 conditions at 100 mW cm(-2) irradiation.

  9. Elaboration of modified poly(NiII-DHS films as electrodes by the electropolymerization of Ni(II-[5,5′-dihydroxysalen] onto indium tin oxide surface and study of their electrocatalytic behavior toward aliphatic alcohols

    Directory of Open Access Journals (Sweden)

    Ali Ourari

    2017-11-01

    Full Text Available Nickel(II-DHS complex was obtained from N,N′-bis(2,5-dihydroxybenzylidene-1,2-diaminoethane (H2DHS ligand and nickel acetate tetrahydrated in ethanolic solution with stirring under reflux. This complex, dissolved in an alkaline solution, was oxidized to form electroactive films strongly adhered on the ITO (indium tin oxide electrode surface. In this alkaline solution, the poly-[NiII-DHS]/ITO films showed the typical voltammetric response of (Ni2+/Ni3+ redox couple centers which are immobilized in the polymer-film. The modified electrodes (MEs obtained were also characterized by several techniques such as scanning electronic microscopy, atomic force microscopy and electrochemical methods. The electrocatalytic behavior of these MEs toward the oxidation reaction of some aliphatic alcohols such as methanol, ethanol, 2-Methyl-1-propanol and isopropanol was investigated. The voltammograms recorded with these alcohols showed good electrocatalytic efficiency. The electrocatalytic currents were at least 80 times higher than those obtained for the oxidation of methanol on electrodes modified with nickel hydroxide films in alkaline solutions. We noticed that these electrocatalytic currents are proportional to the concentration of methanol (0.050–0.30 μM. In contrast, those recorded for the oxidation of other aliphatic short chain alcohols such as ethanol, 2-methyl-1-propanol and isopropanol are rather moderately weaker. In all cases the electrocatalytic currents presented a linear dependence with the concentration of alcohol. These modified electrodes could be applied as alcohol sensors.

  10. Telomerase reverse transcriptase genetically modified adipose tissue derived stem cells improves erectile dysfunction by inhibiting oxidative stress and enhancing proliferation in rat model.

    Science.gov (United States)

    Wu, Xiao-Jun; Shen, Wen-Hao; He, Peng; Zhou, Xiao-Zhou; Zhi, Yi; Dai, Qiang; Chen, Zhi-Wen; Zhou, Zhan-Song

    2017-08-01

    Erectile dysfunction (ED) is considered to be incapable of obtaining or/and keeping a sufficient erection function to receive the satisfactory during the sexual intercourse. This study aims to investigate the effects of telomerase reverse transcriptase (hTERT) modified adipose tissue derived stem cells (ADSCs) autologously injected into cavernosa of the ED rats on erectile function. The ADSCs were isolated form the rat subcutaneous adipose tissue sample, and identified by examining the CD29 and CD44 molecule. The ED model was established by using 100μg/kg apomorphine (APO). The adenovirus expressing rat hTERT (Ade-hTERT vector) was established, and transfected into ADSCs and injected into ED rat model, respectively. Telomerase activity, cell growth, cell apoptosis were analyzed by using TRAP ELISA assay, CCK8 assay and flow cytometry assay, respectively. The trophic growth factors were examined by using enzyme-linked immunosorbent assay (ELISA). The mRNA and proteins were detected by using semi-quantitative PCR and western blot assay, respectively. Ade-hTERT vector was highly expressed in both ADSCs and ED rat mode. The hTERT expression enhanced the telomerase activity, inhibits cell apoptosis and enhances proliferation of ADSCs (P<0.05). hTERT expression triggers the secretory function of ADSCs and induces differentiative potential of ADSCs. hTERT expression inhibits apoptosis and increases eNOS and nNOS levels in older ED rats compared to the Ade-vector injected ED rats (P<0.05). In conclusion, the hTERT modification could enhance the ADSCs proliferation, and hTERT modified ADSCs could increase the anti-oxidative stress capacity in the ED rat model. Copyright © 2017. Published by Elsevier Masson SAS.

  11. Preparation of surface–modified lanthanum fluoride–graphene oxide nanohybrids and evaluation of their tribological properties as lubricant additive in liquid paraffin

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Cuizhen; Hou, Xiao; Li, Zhiwei, E-mail: zhiweili@henu.edu.cn; Li, Xiaohong; Yu, Laigui; Zhang, Zhijun

    2016-12-01

    Highlights: • Oleic acid was selected as the modifier according to similar miscibility principle. • OA–LaF{sub 3}–GO nanohybrids were successfully prepared by surface modification technology. • OA–LaF{sub 3}–GO nanohybrids prove excellent antiwear and friction-reducing capacities. - Abstract: Oleic acid surface–modified Lanthanum trifluoride–graphene oxide (OA–LaF{sub 3}–GO) nanohybrids were successfully prepared by surface modification technology. The morphology and phase structure of as-prepared samples were analyzed by means of X-ray diffraction and transmission electron microscopy, Fourier transform infrared spectrometry, Raman spectrometry and thermogravimetry. The results revealed that OA were bonded onto the surface of LaF{sub 3}–GO nanohybrids. Subsequently, the tribological properties of OA–LaF{sub 3}–GO nanohybrids as lubricant additive in liquid paraffin were evaluated with a four-ball machine, and the morphology and elemental composition of worn steel surfaces were examined on a scanning electron microscope with an energy dispersive spectrometer. Tribological results showed that OA–LaF{sub 3}–GO nanohybrids had excellent friction reduction and antiwear ability at the loading of 0.5 wt.% OA–LaF{sub 3}–GO nanohybrids, compared to liquid paraffin alone. The results of energy dispersive spectrometer revealed that improved tribological properties resulted from OA–LaF{sub 3}–GO could transfer to the rubbed steel surface and decompose to form protective layers, which help to improve tribological properties.

  12. Substituent effect on the oxidation peak potentials of phenol derivatives at ordered mesoporous carbons modified electrode and its application in determination of acidity coefficients (pKa)

    International Nuclear Information System (INIS)

    Zhang, Tingting; Lang, Qiaolin; Zeng, Lingxing; Li, Tie; Wei, Mingdeng; Liu, Aihua

    2014-01-01

    In this paper, the relationship between the electrochemical characteristics and the structure of a series of substituted phenol derivatives with electron-donating or electron-withdrawing groups were studied by voltammetry using ordered mesoporous carbons (OMCs) modified glassy carbon electrode (GCE) (OMCs/GCE). p-Nitrophenol (p-NP) and p-methylphenol were selected as models of electron-withdrawing and electron-donating groups, respectively, to illustrate the electrochemical behavior and reaction mechanism of substituted phenols. Voltammetric study showed that the oxidation peak potential (E pa ) of substituted phenols with an electron-withdrawing group was systematically higher than that of substituted phenols with an electron-donating group. That is, the direct electrochemical oxidation of substituted phenol with an electron-withdrawing group is more difficult than that of substituted phenol with an electron-donating group. The E pa value shifted negatively with the increase of pKa for both p-substituted phenols and o-substituted phenols with the equations of pKa = −6.986 E pa + 13.261 (for p-substituted phenols) and pKa = −7.929 E pa + 13.831 (for o-substituted phenols). Thus, a simple and novel method was proposed for the precise prediction of the pKa of substituted phenols by determining E pa values with voltammetry at OMCs/GCE, which matched fairly with the results calculated from Hammett's constants. Thus, the present work may provide additional strategy to determine pKa values and investigate possible mechanisms of some organic reactions. In addition, by making use of the substituent effect, different p-substituted phenols (or o-substituted phenols) can be well separated and identified at OMCs/GCE by voltametry, which may find possible applications in simultaneous detection of p-substituted phenols (or o-substituted phenols)

  13. Preparation and characterization of sugar cane bagasse fiber modified with nanoparticles of zirconium oxide; Preparacao e caracterizacao de fibras de bagaco de cana modificadas com nanoparticulas de oxido de zirconio

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, K.C.C. de; Mulinari, D.R.; Voorwald, H.C.J.; Cioffi, M.O.H., E-mail: kcccarvalho@hotmail.com.b [UNESP, Guaratingueta, SP (Brazil). Fac. de Engenharia. Dept. de Materiais e Tecnologia(FEG)

    2010-07-01

    The sugar cane bagasse fiber are renewable materials and have great application potential when used as reinforcement in a polymer matrix to give rise to composite materials and as supports for adsorption of heavy metals. This paper therefore describes the preparation and characterization of bleached and hydrated zirconium oxide modified sugar cane bagasse fiber by conventional precipitation method. Through the technique of electron microscopy we observed the presence of oxide nanoparticles on the fiber surface, proving the efficiency of the conventional precipitation method. With the X-ray diffraction analysis it was determined a decrease of 6.2% in the crystallinity index of modified fibers when compared to the bleached fibers showing the deposition of amorphous zirconium oxide on the fiber surface. (author)

  14. An amperometric biosensor based on acetylcholinesterase immobilized onto iron oxide nanoparticles/multi-walled carbon nanotubes modified gold electrode for measurement of organophosphorus insecticides

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Nidhi [Department of Biochemistry, M.D. University, Rohtak 124001, Haryana (India); Pundir, Chandra Shekhar, E-mail: pundircs@rediffmail.com [Department of Biochemistry, M.D. University, Rohtak 124001, Haryana (India)

    2011-09-02

    Graphical abstract: The stepwise amperometric biosensor fabrication process and immobilized acetylcholinesterase inhibition in pesticide solution. Highlights: {center_dot} Constructed a novel composite material using Fe{sub 3}O{sub 4}NP and c-MWCNT at Au electrode for electrocatalysis. {center_dot} The properties of nanoparticles modified electrodes were studied by SEM, FTIR, CVs and EIS. {center_dot} The biosensor exhibited good sensitivity (0.475 mA {mu}M{sup -1}) {center_dot} The half life of electrode was 2 months. {center_dot} The sensor was suitable for trace detection of OP pesticide residues in milk and water. - Abstract: An acetylcholinesterase (AChE) purified from maize seedlings was immobilized covalently onto iron oxide nanoparticles (Fe{sub 3}O{sub 4}NP) and carboxylated multi walled carbon nanotubes (c-MWCNT) modified Au electrode. An organophosphorus (OP) biosensor was fabricated using this AChE/Fe{sub 3}O{sub 4}/c-MWCNT/Au electrode as a working electrode, Ag/AgCl as standard and Pt wire as an auxiliary electrode connected through a potentiostat. The biosensor was based on inhibition of AChE by OP compounds/insecticides. The properties of nanoparticles modified electrodes were studied by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS). The synergistic action of Fe{sub 3}O{sub 4}NP and c-MWCNT showed excellent electrocatalytic activity at low potential (+0.4 V). The optimum working conditions for the sensor were pH 7.5, 35 deg. C, 600 {mu}M substrate concentration and 10 min for inhibition by pesticide. Under optimum conditions, the inhibition rates of OP pesticides were proportional to their concentrations in the range of 0.1-40 nM, 0.1-50 nM, 1-50 nM and 10-100 nM for malathion, chlorpyrifos, monocrotophos and endosulfan respectively. The detection limits were 0.1 nM for malathion and chlorpyrifos, 1 nM for monocrotophos and 10 nM for endosulfan. The

  15. In vitro and in vivo comparative study of the phototherapy anticancer activity of hyaluronic acid-modified single-walled carbon nanotubes, graphene oxide, and fullerene

    Science.gov (United States)

    Hou, Lin; Yuan, Yujie; Ren, Junxiao; Zhang, Yinling; Wang, Yongchao; Shan, Xiaoning; Liu, Qi; Zhang, Zhenzhong

    2017-08-01

    In this work, carbon nanomaterials, single-walled carbon nanotubes (SWNT), graphene oxide (GO), and fullerene (C60) were modified by hyaluronic acid (HA) to obtain water-soluble and biocompatible nanomaterials with high tumor-targeting capacity and then the comparative study of these hyaluronic acid-modified carbon nanomaterials was made in vitro and in vivo. The conjugates of hyaluronic acid and carbon nanomaterials, namely, HA-SWNT, HA-GO, HA-C60, were confirmed by UV/Vis spectrum, Fourier transform infrared spectroscopy (FTIR), and a transmission electron microscope (TEM). After HA modification, the sizes of HA-SWNT, HA-GO, and HA-C60 were in a range of 70 to 300 nm, and all the three HA-modified materials were at negative potential, demonstrating that HA modification was in favor of extravasation of carbon materials into a tumor site due to enhanced permeability and retention effect of tumor. Photothermal conversion in vitro test demonstrated excellent photothermal sensitivity of HA-SWNT and HA-GO. But the reactive oxygen yield of HA-C60 was the highest compared with the others under visible light irradiation, which proved the good photodynamic therapy effect of HA-C60. In addition, cytotoxicity experiments exhibited that the inhibitory efficacy of HA-SWNT was the lowest, the second was HA-C60, and the highest was HA-GO, which was consistent with the uptake degree of them. While under the laser irradiation, the cell inhibition of the HA-SWNT was the highest, the second was HA-GO, and the last was HA-C60. In vivo evaluation of the three targeting carbon nanomaterials was consistent with the cytotoxicity assay results. Taken together, the results demonstrated that HA-SWNT and HA-GO were suited for photothermal therapy (PTT) agents for their good photothermal property, while HA-C60 was used as a kind of photodynamic therapy (PDT) agent for its photodynamic effect.

  16. Determination of Zinc, Cadmium, Lead, Copper and Silver Using a Carbon Paste Electrode and a Screen Printed Electrode Modified with Chromium(III) Oxide.

    Science.gov (United States)

    Koudelkova, Zuzana; Syrovy, Tomas; Ambrozova, Pavlina; Moravec, Zdenek; Kubac, Lubomir; Hynek, David; Richtera, Lukas; Adam, Vojtech

    2017-08-09

    In this study, the preparation and electrochemical application of a chromium(III) oxide modified carbon paste electrode (Cr-CPE) and a screen printed electrode (SPE), made from the same material and optimized for the simple, cheap and sensitive simultaneous determination of zinc, cadmium, lead, copper and the detection of silver ions, is described. The limits of detection and quantification were 25 and 80 µg·L -1 for Zn(II), 3 and 10 µg·L -1 for Cd(II), 3 and 10 µg·L -1 for Pb(II), 3 and 10 µg·L -1 for Cu(II), and 3 and 10 µg·L -1 for Ag(I), respectively. Furthermore, this promising modification was transferred to the screen-printed electrode. The limits of detection for the simultaneous determination of zinc, cadmium, copper and lead on the screen printed electrodes were found to be 350 µg·L -1 for Zn(II), 25 µg·L -1 for Cd(II), 3 µg·L -1 for Pb(II) and 3 µg·L -1 for Cu(II). Practical usability for the simultaneous detection of these heavy metal ions by the Cr-CPE was also demonstrated in the analyses of wastewaters.

  17. Microfluidic Encapsulation of Prickly Zinc-Doped Copper Oxide Nanoparticles with VD1142 Modified Spermine Acetalated Dextran for Efficient Cancer Therapy.

    Science.gov (United States)

    Zhang, Hongbo; Liu, Dongfei; Wang, Liang; Liu, Zehua; Wu, Runrun; Janoniene, Agne; Ma, Ming; Pan, Guoqing; Baranauskiene, Lina; Zhang, Linlin; Cui, Wenguo; Petrikaite, Vilma; Matulis, Daumantas; Zhao, Hongxia; Pan, Jianming; Santos, Hélder A

    2017-06-01

    Structural features of nanoparticles have recently been explored for different types of applications. To explore specific particles as nanomedicine and physically destroy cancer is interesting, which might avoid many obstacles in cancer treatment, for example, drug resistance. However, one key element and technical challenge of those systems is to selectively target them to cancer cells. As a proof-of-concept, Prickly zinc-doped copper oxide (Zn-CuO) nanoparticles (Prickly NPs) have been synthesized, and subsequently encapsulated in a pH-responsive polymer; and the surface has been modified with a novel synthesized ligand, 3-(cyclooctylamino)-2,5,6-trifluoro-4-[(2-hydroxyethyl)sulfonyl] benzenesulfonamide (VD1142). The Prickly NPs exhibit very effective cancer cell antiproliferative capability. Moreover, the polymer encapsulation shields the Prickly NPs from unspecific nanopiercing and, most importantly, VD1142 endows the engineered NPs to specifically target to the carbonic anhydrase IX, a transmembrane protein overexpressed in a wide variety of cancer tumors. Intracellularly, the Prickly NPs disintegrate into small pieces that upon endosomal escape cause severe damage to the endoplasmic reticulum and mitochondria of the cells. The engineered Prickly NP is promising in efficient and targeted cancer treatment and it opens new avenue in nanomedication. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. The influence of antioxidant and post-synthetic treatment on the properties of biodegradable poly(butylene succinates modified with poly(propylene oxide

    Directory of Open Access Journals (Sweden)

    DRAGANA PEPIC

    2007-12-01

    Full Text Available Novel poly(ester–ethers based on poly(butylene succinate (PBS as the hard segments and 30 mass % of poly(propylene oxide (PPO as the soft segments were synthesized with varying amount of the antioxidant (N,N'-diphenyl-p-phenylenediamine, DPPD. The influences of the addition of DPPD and the impact of post-synthetic treatment by precipitation on the molecular structure, thermal and physical properties, as well as on the storage stability of the biodegradable aliphatic copolyesters, were investigated. The structure and composition of the copolymers were determined by means of 1H-NMR spectroscopy. The molecular weight and polydispersity of the poly(ester–ethers were evaluated from solution viscosity and GPC measurements. The thermal properties and stability were evaluated, respecttively, by means of DSC and non-isothermal thermogravimetry in an inert nitrogen atmosphere. The biodegradability potential of the polymers was studied in hydrolytic and enzymatic degradation tests with Candida cylindracea lipase by monitoring the weight loss of polymer films after incubation. The weight losses of the samples increased with time and were in the range from 1 to 5 mass % after 4 weeks. GPC analysis confirmed that there were changes in the molecular weight of the copolyesters during both hydrolytic and enzymatic degradation tests, leading to the conclusion that the degradation mechanism of poly(butylenes succinate modified with PPO occurred through surface erosion and bulk degradation.

  19. Preparation, characterization and application of superparamagnetic iron oxide nanoparticles modified with natural polymers for removal of {sup 60}Co-radionuclides from aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Sharaf El-Deen, Gehan E. [Atomic Energy Authority, Cairo (Egypt). Radioactive Waste Management Dept.; Imam, Neama G. [Atomic Energy Authority, Cairo (Egypt). Experimental Physics Dept.; Elettra, Sincrotrone, Trieste (Italy); Ayoub, Refaat R. [Atomic Energy Authority, Cairo (Egypt). Nuclear Chemistry Dept.

    2017-04-01

    Superparamagnetic iron oxide nanoparticles (IO-MNPs) coated with natural polymers, starch (IO-S MNPs) and dextrin (IO-D MNPs), were synthesized by modified co-precipitation method. IO and hybrid-IO-MNPs were characterized by XRD, SEM, HRTEM, FT-IR spectroscopy, vibrating sample magnetometer (VSM) and zeta potential (ZP). IO-S MNPs and IO-D MNPs have IO core-shell structure with core of 10.8 nm and 13.8 nm and shell of 7.5 nm and 5.9 nm, respectively. The efficiency of the hybrid IO-MNPs for sorption of {sup 60}Co(II)-radionuclides from aqueous solution was investigated under varying experimental conditions. Kinetic data were described well by pseudo-second-order mode, sorption isotherms were fitted quite with Freundlich model with maximum adsorption capacity 36.89 (mmol.g{sup -1})/(L.mmol{sup -1}){sup n} for IO-S MNPs and 24.9 (mmol.g{sup -1})/(L.mmol{sup -1}){sup n} for IO-D MNPs. Sorption of {sup 60}Co-radionuclides by IO-S MNPs was suppressed with salinity and most of the adsorbed {sup 60}Co onto IO-S MNPs could be remove with 0.1 M HCl solution. IO-S MNPs exhibits superparamagnetic properties, easier separation according to higher saturation magnetization (47 emu/g) and better adsorption for {sup 60}CO-radionuclides than IO-D MNPs.

  20. A Voltammetric Sensor Based on Chemically Reduced Graphene Oxide-Modified Screen-Printed Carbon Electrode for the Simultaneous Analysis of Uric Acid, Ascorbic Acid and Dopamine

    Directory of Open Access Journals (Sweden)

    Prosper Kanyong

    2016-12-01

    Full Text Available A disposable screen-printed carbon electrode (SPCE modified with chemically reduced graphene oxide (rGO (rGO-SPCE is described. The rGO-SPCE was characterized by UV-Vis and electrochemical impedance spectroscopy, and cyclic voltammetry. The electrode displays excellent electrocatalytic activity towards uric acid (UA, ascorbic acid (AA and dopamine (DA. Three resolved voltammetric peaks (at 183 mV for UA, 273 mV for AA and 317 mV for DA, all vs. Ag/AgCl were found. Differential pulse voltammetry was used to simultaneously detect UA, AA and DA in their ternary mixtures. The linear working range extends from 10 to 3000 μM for UA; 0.1 to 2.5 μM, and 5.0 to 2 × 104 µM for AA; and 0.2 to 80.0 μM and 120.0 to 500 µM for DA, and the limits of detection (S/N = 3 are 0.1, 50.0, and 0.4 μM, respectively. The performance of the sensor was evaluated by analysing spiked human urine samples, and the recoveries were found to be well over 98.0% for the three compounds. These results indicate that the rGO-SPCE represents a sensitive analytical sensing tool for simultaneous analysis of UA, AA and DA.

  1. Theoretical Investigation of Half-Metallic Oxides XFeO3 (X = Sr, Ba) via Modified Becke-Johnson Potential Scheme

    Science.gov (United States)

    Maqsood, Saba; Rashid, Muhammad; Din, Fasih Ud; Saddique, M. Bilal; Laref, A.

    2018-03-01

    The cubic XFeO3 (X = Sr, Ba) perovskite oxides are studied for their thermodynamic stability in the ferromagnetic phase by using density functional theory calculations. We also explore the elastic properties of these compounds in terms of elastic constants C ij, bulk modulus B, shear modulus G, anisotropy factor A, Poisson's ratio ν and the B/ G ratio. The electronic properties are examined to elucidate the magnetic order, and the thermoelectric properties of XFeO3 (X = Sr, Ba) materials are also presented. The modified Becke-Johnson local density approximation scheme has been used to compute the electronic band structure and density of states, which show that these materials are half-metallic ferromagnetic. We study the magnetic properties by computing the crystal field energy (ΔCF), John-Teller energy (ΔJT) and the exchange splitting energies Δx( d) and Δx( pd). Our results indicate that strong hybridization causes a decrease in the magnetic moment of Fe, which then produces permanent magnetic moments in the nonmagnetic sites.

  2. Preparation and characterization of magnetic allylamine modified graphene oxide-poly(vinyl acetate-co-divinylbenzene) nanocomposite for vortex assisted magnetic solid phase extraction of some metal ions.

    Science.gov (United States)

    Khan, Mansoor; Yilmaz, Erkan; Sevinc, Basak; Sahmetlioglu, Ertugrul; Shah, Jasmin; Jan, Muhammad Rasul; Soylak, Mustafa

    2016-01-01

    Magnetic allylamine modified graphene oxide-poly(vinyl acetate-co-divinylbenzene) (MGO-DVB-VA) was synthesized and used for magnetic solid phase extraction of Pb(II), Cd(II), Cu(II), Ni(II) and Co(II) prior to their determination by flame atomic absorption spectroscopy. The adsorbent surface functional group was characterized by using FT-IR and Raman spectroscopy. XRD pattern was used to determine the layers of GO. Surface morphology and elemental composition of the adsorbent were evaluated by using SEM and EDX analysis. Various parameters, effecting adsorption efficiency like initial solution pH, adsorbent dose, type and volume of eluent, volume of sample and diverse ions effects were optimized. The preconcentration factor (PF) is 40 for all the metals and the limits of detection for Pb, Cd, Cu, Ni and Co are in the range of 0.37-2.39 µg L(-1) and relative standard deviation below 3.1%. The method was validated by using the method for certified reference materials (Tobacco Leaves (INCT-OBTL-5), Tomato Leaves (1573a), Certified Water (SPS-ww2) and Certified Water (TMDA 64-2)). The method was successfully applied for natural water and food samples. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Effects of aeration and internal recycle flow on nitrous oxide emissions from a modified Ludzak-Ettinger process fed with glycerol.

    Science.gov (United States)

    Song, Kang; Suenaga, Toshikazu; Harper, Willie F; Hori, Tomoyuki; Riya, Shohei; Hosomi, Masaaki; Terada, Akihiko

    2015-12-01

    Nitrous oxide (N2O) is emitted from a modified Ludzak-Ettinger (MLE) process, as a primary activated sludge system, which requires mitigation. The effects of aeration rates and internal recycle flow (IRF) ratios on N2O emission were investigated in an MLE process fed with glycerol. Reducing the aeration rate from 1.5 to 0.5 L/min increased gaseous the N2O concentration from the aerobic tank and the dissolved N2O concentration in the anoxic tank by 54.4 and 53.4 %, respectively. During the period of higher aeration, the N2O-N conversion ratio was 0.9 % and the potential N2O reducers were predominantly Rhodobacter, which accounted for 21.8 % of the total population. Increasing the IRF ratio from 3.6 to 7.2 decreased the N2O emission rate from the aerobic tank and the dissolved N2O concentration in the anoxic tank by 56 and 48 %, respectively. This study suggests effective N2O mitigation strategies for MLE systems.

  4. Determination of Zinc, Cadmium, Lead, Copper and Silver Using a Carbon Paste Electrode and a Screen Printed Electrode Modified with Chromium(III Oxide

    Directory of Open Access Journals (Sweden)

    Zuzana Koudelkova

    2017-08-01

    Full Text Available In this study, the preparation and electrochemical application of a chromium(III oxide modified carbon paste electrode (Cr-CPE and a screen printed electrode (SPE, made from the same material and optimized for the simple, cheap and sensitive simultaneous determination of zinc, cadmium, lead, copper and the detection of silver ions, is described. The limits of detection and quantification were 25 and 80 µg·L−1 for Zn(II, 3 and 10 µg·L−1 for Cd(II, 3 and 10 µg·L−1 for Pb(II, 3 and 10 µg·L−1 for Cu(II, and 3 and 10 µg·L−1 for Ag(I, respectively. Furthermore, this promising modification was transferred to the screen-printed electrode. The limits of detection for the simultaneous determination of zinc, cadmium, copper and lead on the screen printed electrodes were found to be 350 µg·L−1 for Zn(II, 25 µg·L−1 for Cd(II, 3 µg·L−1 for Pb(II and 3 µg·L−1 for Cu(II. Practical usability for the simultaneous detection of these heavy metal ions by the Cr-CPE was also demonstrated in the analyses of wastewaters.

  5. A glassy carbon electrode modified with β-cyclodextin, multiwalled carbon nanotubes and graphene oxide for sensitive determination of 1,3-dinitrobenzene

    International Nuclear Information System (INIS)

    Li, Junhua; Feng, Haibo; Liu, Jinlong; Liu, Youcai; Jiang, Jianbo; Feng, Yonglan; Qian, Dong

    2014-01-01

    We are presenting a host-guest electrochemical platform for sensing the pollutant 1,3-dinitrobenzene. The method is based on the use of a glassy carbon electrode (GCE) covered with a composite made from multiwalled carbon nanotubes and graphene oxide, and functionalized with β-cyclodextrin (β-CD). The resultant composite was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and electrochemical techniques. The modified GCE was used for the sensitive detection of 1,3-dinitrobenzene (DNB) at working voltages of −355 mV and −483 mV. Due to the specific recognition property of β-CD and the excellent electronic properties of the carbon nanomaterials, the electrode exhibits outstanding supramolecular recognition and enhanced electrochemical response to DNB compared to more conventional electrodes. Under optimum conditions, the peak currents vary linearly with the DNB concentrations in the range from 0.02 to 30.0 μM, and the detection limit is 5.0 nM (at an S/N of 3). The electrode exhibits long-term stability and has been successfully applied to the determination of DNB in spiked soil and water samples. (author)

  6. Highly efficient ultrasonic-assisted removal of Hg(II) ions on graphene oxide modified with 2-pyridinecarboxaldehyde thiosemicarbazone: Adsorption isotherms and kinetics studies.

    Science.gov (United States)

    Tadjarodi, Azadeh; Moazen Ferdowsi, Somayeh; Zare-Dorabei, Rouholah; Barzin, Ahmad

    2016-11-01

    A novel adsorbent, based on modifying graphene oxide (GO) chemically with 2-pyridinecarboxaldehyde thiosemicarbazone (2-PTSC) as ligand, was designed by facile process for removal of Hg(II) from aqueous solution. Characterization of the adsorbent was performed using various techniques, such as FT-IR, XRD, XPS, SEM and AFM analysis. The adsorption capacity was affected by variables such as adsorbent dosage, pH solution, Hg(2+) initial concentration and sonicating time. These variables were optimized by rotatable central composite design (CCD) under response surface methodology (RSM). The predictive model for Hg(II) adsorption was constructed and applied to find the best conditions at which the responses were maximized. In this conditions, the adsorption capacity of this adsorbent for Hg(2+) ions was calculated to be 309mgg(-1) that was higher than that of GO. Appling the ultrasound power combined with adsorption method was very efficient in shortening the removal time of Hg(2+) ions by enhancing the dispersion of adsorbent and metal ions in solution and effective interactions among them. The adsorption process was well described by second-order kinetic and Langmuir isotherm model in which the maximum adsorption capacity (Qm) was found to be 555mgg(-1) for adsorption of Hg(2+) ions over the obtained adsorbent. The performance of adsorbent was examined on the real wastewaters and confirmed the applicability of adsorbent for practical applications. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Study of the Effect of Grafting Method on Surface Polarity of Tempo-Oxidized Nanocellulose Using Polycaprolactone as the Modifying Compound: Esterification versus Click-Chemistry

    Directory of Open Access Journals (Sweden)

    Abdelhaq Benkaddour

    2013-12-01

    Full Text Available Esterification and click-chemistry were evaluated as surface modification treatments for TEMPO-oxidized nanocelluloses (TONC using Polycaprolactone-diol (PCL as modifying compound in order to improve the dispersion of nanofibers in organic media. These two grafting strategies were analyzed and compared. The first consists of grafting directly the PCL onto TONC, and was carried out by esterification between hydroxyl groups of PCL and carboxyl groups of TONC. The second strategy known as click-chemistry is based on the 1,3-dipolar cycloaddition reaction between azides and alkyne terminated moieties to form the triazole ring between PCL and TONC. The grafted samples were characterized by transmission electron microscopy (TEM, Fourier transform infrared spectroscopy (FTIR, X-ray photoelectron spectroscopy (XPS, and Thermogravimetry analysis (TGA. Further, the effects of the two treatments on the surface hydrophobization of TONC were investigated by contact angle measurements. The results show that both methods confirm the success of such a modification and the click reaction was significantly more effective than esterification.

  8. A self-assembled 2D/2D-type protonated carbon nitride-modified graphene oxide nanocomposite with improved photocatalytic activity

    Science.gov (United States)

    Xie, Linfang; Ni, Jie; Tang, Bo; He, Guangyu; Chen, Haiqun

    2018-03-01

    A surface charge modified g-C3N4 was successfully prepared by protonation of nitric acid. Combination of the protonated g-C3N4 (pCN) and graphene oxide (GO) layers created a 2D/2D-type composite (pCN/GO) under the synergistic effect of sonication-exfoliation and self-assembly. The obtained 2D nanostructure of pCN/GO was explored by electron microscopy analysis. The photocatalytic degradation of rhodamine B (RhB) and ciprofloxacin (CIP) showed a distinctly high efficiency of pCN/GO-5% with excellent stability, which is superior not only to that of g-C3N4, pCN and g-C3N4/GO-5% nanocomposites we prepared, but also to what was reported previously. The optimized combination of GO and pCN afforded the pCN/GO composite intimate interfacial contact within the heterojunction, which promoted the separation of photogenerated electron-hole pairs as evidenced by zeta potential, photoluminescence and photocurrent measurements. A visible-light photocatalytic degradation mechanism associated with pCN/GO nanocomposites was also proposed.

  9. Surface-enhanced oxidation and detection of Sunset Yellow and Tartrazine using multi-walled carbon nanotubes film-modified electrode.

    Science.gov (United States)

    Zhang, Weikang; Liu, Tao; Zheng, Xiaojiang; Huang, Wensheng; Wan, Chidan

    2009-11-01

    The insoluble multi-walled carbon nanotubes (MWNT) was successfully dispersed into water in the presence of hydrophobic surfactant. After that, MWNT film-coated glassy carbon electrode (GCE) was achieved via dip-coating and evaporating water. Owing to huge surface area, high sorption capacity and subtle electronic properties, MWNT film exhibits highly efficient accumulation efficiency as well as considerable surface enhancement effects to Sunset Yellow and Tartrazine. As a result, the oxidation peak currents of Sunset Yellow and Tartrazine remarkably increase at the MWNT film-modified GCE. Based on this, a novel electrochemical method was developed for the simultaneous determination of Sunset Yellow and Tartrazine. The limits of detection are 10.0 ng mL(-1) (2.2 x 10(-8)mol L(-1)) and 0.1 microg mL(-1) (1.88 x 10(-7)mol L(-1)) for Sunset Yellow and Tartrazine. Finally, the proposed method was successfully used to detect Sunset Yellow and Tartrazine in soft drinks.

  10. Development of disposable bulk-modified screen-printed electrode based on bismuth oxide for stripping chronopotentiometric analysis of lead (II) and cadmium (II) in soil and water samples

    Energy Technology Data Exchange (ETDEWEB)

    Kadara, Rashid O. [Cranfield Health, Cranfield University, Silsoe, Bedfordshire MK45 4DT (United Kingdom); School of Science and Technology, Nottingham Trent University, Clifton Campus, Nottinghamshire NG11 8NS (United Kingdom)], E-mail: kayusee2001@yahoo.co.uk; Tothill, Ibtisam E. [Cranfield Health, Cranfield University, Silsoe, Bedfordshire MK45 4DT (United Kingdom)

    2008-08-08

    A bulk-modified screen-printed carbon electrode characterised for metal ion detection is presented. Bismuth oxide (Bi{sub 2}O{sub 3}) was mixed with graphite-carbon ink to obtain the modified electrode. The best composition was 2% Bi{sub 2}O{sub 3} (wt%) in the graphite-carbon ink. The modified electrode with onboard screen-printed carbon counter and silver-silver chloride pseudo-reference electrodes exhibited good performance in the electrochemical measurement of lead (II) and cadmium (II). The electrode displayed excellent linear behaviour in the concentration range examined (20-300 {mu}g L{sup -1}) with limits of detection of 8 and 16 {mu}g L{sup -1} for both lead (II) and cadmium (II), respectively. The analytical utility of the modified electrode was illustrated by the stripping chronopotentiometric determinations of lead (II) in soil extracts and wastewater samples.

  11. Development of disposable bulk-modified screen-printed electrode based on bismuth oxide for stripping chronopotentiometric analysis of lead (II) and cadmium (II) in soil and water samples

    International Nuclear Information System (INIS)

    Kadara, Rashid O.; Tothill, Ibtisam E.

    2008-01-01

    A bulk-modified screen-printed carbon electrode characterised for metal ion detection is presented. Bismuth oxide (Bi 2 O 3 ) was mixed with graphite-carbon ink to obtain the modified electrode. The best composition was 2% Bi 2 O 3 (wt%) in the graphite-carbon ink. The modified electrode with onboard screen-printed carbon counter and silver-silver chloride pseudo-reference electrodes exhibited good performance in the electrochemical measurement of lead (II) and cadmium (II). The electrode displayed excellent linear behaviour in the concentration range examined (20-300 μg L -1 ) with limits of detection of 8 and 16 μg L -1 for both lead (II) and cadmium (II), respectively. The analytical utility of the modified electrode was illustrated by the stripping chronopotentiometric determinations of lead (II) in soil extracts and wastewater samples

  12. Arsenic Removal from Water Using Various Adsorbents: Magnetic Ion Exchange Resins, Hydrous Ion Oxide Particles, Granular Ferric Hydroxide, Activated Alumina, Sulfur Modified Iron, and Iron Oxide-Coated Microsand

    KAUST Repository

    Sinha, Shahnawaz

    2011-09-30

    The equilibrium and kinetic adsorption of arsenic on six different adsorbents were investigated with one synthetic and four natural types (two surface and two ground) of water. The adsorbents tested included magnetic ion exchange resins (MIEX), hydrous ion oxide particles (HIOPs), granular ferric hydroxide (GFH), activated alumina (AA), sulfur modified iron (SMI), and iron oxide-coated mic - rosand (IOC-M), which have different physicochemical properties (shape, charge, surface area, size, and metal content). The results showed that adsorption equilibriums were achieved within a contact period of 20 min. The optimal doses of adsorbents determined for a given equilibrium concentration of C eq = 10 μg/L were 500 mg/L for AA and GFH, 520–1,300 mg/L for MIEX, 1,200 mg/L for HIOPs, 2,500 mg/L for SMI, and 7,500 mg/L for IOC-M at a contact time of 60 min. At these optimal doses, the rate constants of the adsorbents were 3.9, 2.6, 2.5, 1.9, 1.8, and 1.6 1/hr for HIOPs, AA, GFH, MIEX, SMI, and IOC-M, respectively. The presence of silicate significantly reduced the arsenic removal efficiency of HIOPs, AA, and GFH, presumably due to the decrease in chemical binding affinity of arsenic in the presence of silicate. Additional experiments with natural types of water showed that, with the exception of IOC-M, the adsorbents had lower adsorption capacities in ground water than with surface and deionized water, in which the adsorption capacities decreased by approximately 60–95 % .

  13. Preparation of arginine-modified reduced graphene oxide composite filled in an on-line solid-phase extraction disk and its application in the analysis of heterocyclic aromatic amines.

    Science.gov (United States)

    Cai, Lemei; Xu, Na; Xia, Shujun; Wang, Yiru; Chen, Xi

    2017-07-01

    An arginine-modified reduced graphene oxide composite was prepared in an on-line solid-phase extraction disk and coupled to high-performance liquid chromatography for the re-enrichment of heterocyclic aromatic amines. The synthetic composite presented an excellent adsorption capability because of the ultrahigh active surface area of graphene and the abundant alkaline groups of arginine. The adsorption capacity of it was 52.7 mg 2-amino-3-methyl-imidazo[4,5-f]-quinoline per gram, nearly twice that of threonine-modified reduced graphene oxide composite, glutamic acid modified reduced graphene oxide composite, and reduced graphene oxide. This on-line method was successfully applied to the detection of a series of heterocyclic aromatic amines in beef jerky. After clean-up and re-enrichment of the on-line solid-phase extraction disk, the chromatographic background of the sample was low and the shape of chromatographic peaks was sharp. The method detection limit was in the range of 0.30-0.49 ng/g, and the recovery was in the range of 82.0-111.5%. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. [Determination of deuterium concentration in foods and influence of water with modified isotopic composition on oxidation parameters and heavy hydrogen isotopes content in experimental animals].

    Science.gov (United States)

    Basov, A A; Bykov, I M; Baryshev, M G; Dzhimak, S S; Bykov, M I

    2014-01-01

    The article presents the results of the study of the deuterium (D) content in food products as well as the influence of deuterium depleted water (DDW) on the concentration of heavy hydrogen isotopes in the blood and lyophilized tissues of rats. The most significant difference in the content of D was found between potato and pork fat, which indexes the standard delta notation (δ) D in promille, related to the international standard SMOW (Standard Mean Ocean of Water) amounted to -83,2 per thousand and -250,7 per thousand, respectively (phydrogen atoms in the body. The data obtained in the experimental modeling of the diet of male Wistar rats in the age of 5-6 mo (weight 235 ± 16 g) using DDW (δD = -743,2 per thousand) instead of drinking water (δD = -37,0 per thousand) with identical mineral composition showed that after 2 weeks significant (p tissue") is due to different rates ofisotopic exchange reactions in plasma and tissues (liver, kidney, heart), which can be explained by entering into the composition of a modified diet of organic substrates with more than DDW concentration D, which are involved in the construction of cellular structures and eventually lead to a redistribution of D and change direction of D/H gradient "plasmamodified isotopic composition, aimed at reducing the level of heavy non-radioactive atoms will allow the targeted nutritional correction of prooxidant-antioxidant status of the population in areas with adverse environmental conditions, stimulating by created isotopic D/H gradient cytoprotective mechanisms influencing the various components of nonspecific protection, including free radical oxidation processes. And then again, periodic assessment of the isotopic composition of nutrients will monitor the quality of food consumed by the population, and if

  15. Selective oxidation

    International Nuclear Information System (INIS)

    Cortes Henao, Luis F.; Castro F, Carlos A.

    2000-01-01

    It is presented a revision and discussion about the characteristics and factors that relate activity and selectivity in the catalytic and not catalytic partial oxidation of methane and the effect of variables as the temperature, pressure and others in the methane conversion to methanol. It thinks about the zeolites use modified for the catalytic oxidation of natural gas

  16. Synthesis and characterization of oleic acid surface modified magnetic iron oxide nanoparticles by using biocompatible w/o microemulsion for heavy metal removal

    Science.gov (United States)

    Rose, Laili Che; Suhaimi, Hamdan; Mamat, Mazidah; Lik, Thang Zhe

    2017-09-01

    Oleic acid modified magnetic iron oxide nanoparticles (OA-MIONs) was prepared for removal of Cu2+ ion from aqueous solution. OA-MIONs was prepared by W/O microemulsion template which composed of mixed non-ionic surfactants and 1-hexanol as emulsifier. The effect of weight ratio of the constituent of microemulsion template on the physical and chemical properties of OA-MIONs was studied by characterization using Fourier transform infrared (FT-IR), scanning electron microscopy (SEM) and X-ray powder diffraction (XRD) analysis. FT-IR spectra showed that all templates shared similar chemical structure with slight difference in the peak intensity. Scanning electron micrograph illustrated that the OA-MIONs synthesized via template with the lowest weight ratio of emulsifier to heptane had a more regular spherical shape and was well-distributed. XRD had confirmed that the identity of synthesized OA-MIONs was Fe3O4. Based on the characterization result, the template with lowest weight ratio of emulsifier to heptane was chosen for the heavy metal adsorption study. The adsorption capacity OA-MIONs as a function of pH, contact time and adsorbent dosage were studied. The adsorption process reached equilibrium for 90 minutes and successfully adsorbed 43% of Cu2+ ion from aqueous solution. The adsorption behavior was well described by Langmuir isotherm. The maximum adsorption capacity was determined and found to be 555.56 mg/g. The value of Langmuir equilibrium parameter, RL was found between 0 and 1, suggested that a favorable monolayer adsorption process had taken out.

  17. Dispersive solid phase micro-extraction of mercury(II from environmental water and vegetable samples with ionic liquid modified graphene oxide nanoparticles

    Directory of Open Access Journals (Sweden)

    Nasrollahpour Atefeh

    2017-01-01

    Full Text Available A new dispersive solid phase micro-extraction (dispersive-SPME method for separation and preconcentration of mercury(II using ionic liquid modified magnetic reduced graphene oxide (IL-MrGO nanoparticles, prior to the measurement by cold vapour atomic absorption spectrometry (CV-AAS has been developed. The IL-MrGO composite was characterized by Brunauer– Emmett–Teller method (BET for adsorption-desorption measurement, thermogravimetric analysis (TGA, powder X-ray diffraction (XRD and X-ray photoelectron spectroscopy (XPS. The method is based on the sorption of mercury( II on IL-MrGO nanoparticles due to electrostatic interaction and complex formation of ionic liquid part of IL-MrGO with mercury(II. The effect of experimental parameters for preconcentration of mercury(II, such as solution type, concentration and volume of the eluent, pH, time of the sorption and desorption, amount of the sorbent and coexisting ion concentration have been optimized. Under the optimized conditions, a linear response was obtained in the concentration range of 0.08–10 ng mL-1 with a determination coefficient of 0.9995. The limit of detection (LOD of the method at a signal to noise ratio of 3 was 0.01 ng mL-1. Intra-day and inter-day precisions were obtained equal to 3.4 and 4.5 %, respectively. The dispersive solid phase micro-extraction of mercury(II on IL-MrGO nanoparticles coupled with cold vapour atomic absorption spectrometry was successfully used for extraction and determination of mercury(II in water and vegetable samples.

  18. Toxicity of surface-modified copper oxide nanoparticles in a mouse macrophage cell line: Interplay of particles, surface coating and particle dissolution.

    Science.gov (United States)

    Líbalová, Helena; Costa, Pedro M; Olsson, Magnus; Farcal, Lucian; Ortelli, Simona; Blosi, Magda; Topinka, Jan; Costa, Anna L; Fadeel, Bengt

    2018-04-01

    The rapid dissolution of copper oxide (CuO) nanoparticles (NPs) with release of ions is thought to be one of the main factors modulating their toxicity. Here we assessed the cytotoxicity of a panel of CuO NPs (12 nm ± 4 nm) with different surface modifications, i.e., anionic sodium citrate (CIT) and sodium ascorbate (ASC), neutral polyvinylpyrrolidone (PVP), and cationic polyethylenimine (PEI), versus the pristine (uncoated) NPs, using a murine macrophage cell line (RAW264.7). Cytotoxicity, reactive oxygen species (ROS) production, and cellular uptake were assessed. The cytotoxicity results were analyzed by the benchmark dose (BMD) method and the NPs were ranked based on BMD 20 values. The PEI-coated NPs were found to be the most cytotoxic. Despite the different properties of the coating agents, NP dissolution in cell medium was only marginally affected by surface modification. Furthermore, CuCl 2 (used as an ion control) elicited significantly less cytotoxicity when compared to the CuO NPs. We also observed that the antioxidant, N-acetylcysteine, failed to protect against the cytotoxicity of the uncoated CuO NPs. Indeed, the toxicity of the surface-modified CuO NPs was not directly linked to particle dissolution and subsequent Cu burden in cells, nor to cellular ROS production, although CuO-ASC NPs, which were found to be the least cytotoxic, yielded lower levels of ROS in comparison to pristine NPs. Hierarchical cluster analysis suggested, instead, that the toxicity in the current in vitro model could be explained by synergistic interactions between the NPs, their dissolution, and the toxicity of the coating agents. Copyright © 2017 Elsevier Ltd. All rights reserved.

  19. Preparation and Characterization of Graphene Oxide-Modified Sapium sebiferum Oil-Based Polyurethane Composites with Improved Thermal and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Guiying Wu

    2018-01-01

    Full Text Available Bio-based polyurethane (PU composites with superior thermal and mechanical properties have received wide attention. This is due to the recent rapid developments in the PU industry. In the work reported here, novel nano-composites with graphene oxide (GO-modified Sapium sebiferum oil (SSO-based PU has been synthesized via in situ polymerization. GO, prepared using the improved Hummers method from natural graphene (NG, and SSO-based polyol with a hydroxyl value of 211 mg KOH/g, prepared by lipase hydrolysis, were used as raw materials. The microstructures and properties of GO and the nano-composites were both characterized using Fourier transform infrared spectroscopy (FTIR, Raman spectroscopy, X-ray diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, thermogravimetric analysis (TGA, differential scanning calorimetry (DSC, and tensile tests. The results showed that GO with its nano-sheet structure possessed a significant number of oxygen-containing functional groups at the surface. The nano-composites containing 1 wt % GO in the PU matrix (PU1 exhibited excellent comprehensive properties. Compared with those for pure PU, the glass transition temperature (Tg and initial decomposition temperature (IDT of the PU1 were enhanced by 14.1 and 31.8 °C, respectively. In addition, the tensile strength and Young’s modulus of the PU1 were also improved by 126% and 102%, respectively, compared to the pure PU. The significant improvement in both the thermal stability and mechanical properties for PU/GO composites was attributed to the homogeneous dispersion and good compatibility of GO with the PU matrix. The improvement in the properties upon the addition of GO may be attributable to the strong interfacial interaction between the reinforcing agent and the PU matrix.

  20. Preparation of carbon and oxide co-modified LiFePO{sub 4} cathode material for high performance lithium-ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Chun-Chen, E-mail: ccyang@mail.mcut.edu.tw [Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan (China); Battery Research Center of Green Energy, Ming Chi University of Technology, New Taipei City 243, Taiwan (China); Jang, Jer-Huan; Jiang, Jia-Rong [Department of Chemical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan (China); Department of Mechanical Engineering, Ming Chi University of Technology, New Taipei City 243, Taiwan (China)

    2015-09-01

    In this study, a LiFePO{sub 4}/C (LFP/C) material was prepared using a spray dry method. The Li{sub 4}Ti{sub 5}O{sub 12} (LTO) surface modification on LFP/C composite was performed by a sol–gel method. The characteristic properties were examined using X-ray diffraction, micro-Raman spectroscopy, scanning electron microscopy/energy-dispersive X-ray spectroscopy, transmission electron microscopy, an AC impedance method, and the galvanostatic charge/discharge method. Pristine LFP/C powder and the 1–5 wt.% LTO-coated LFP/C composites were compared. The results revealed that the 3 wt.% LTO-coated LFP/C composite showed the best performance among LFP composite samples. It was found that the 3 wt.% LTO-coated LFP/C composite showed discharge capacities of 159 mAh g{sup −1}, 157 mAh g{sup −1}, 154 mAh g{sup −1}, 148 mAh g{sup −1}, 145 mAh g{sup −1}, and 138 mAh g{sup −1} at rates of 0.2C, 0.5C, 1C, 3C, 5C, and 10C, respectively at 55 °C. The long-term cycling performance of the LFP/C composite was greatly improved when the dual hybrid coating (carbon and oxide) was carried out. Moreover, the 3 wt.% LTO-coated LFP/C composite with the lowest fading rate maintained cycling stability at 3C rate at 55 °C after 300 cycles; by contrast, the bare LFP/C sample with the highest fading rate had an unfavorable lifecycle, and its discharge capacity decreased rapidly. A hybrid coating is a feasible method for improving the high temperature performance of LFP/C composites. - Highlights: • A spherical LiFePO{sub 4}/C (LFP/C) material is first prepared by a spray dry process. • Li{sub 4}Ti{sub 5}O{sub 12} (LTO) modified LFP/C composite was carried out by a sol–gel method. • The LFP/C with a hybrid coating showed good cycling performance at elevated temperature. • 3%LTO-LFP/C composite showed excellent cycling stability at 55 °C for 300 cycles test.

  1. Oxidation of elemental mercury by modified spent TiO2-based SCR-DeNOx catalysts in simulated coal-fired flue gas.

    Science.gov (United States)

    Zhao, Lingkui; Li, Caiting; Zhang, Xunan; Zeng, Guangming; Zhang, Jie; Xie, Yin'e

    2016-01-01

    In order to reduce the costs, the recycle of spent TiO2-based SCR-DeNOx catalysts were employed as a potential catalytic support material for elemental mercury (Hg(0)) oxidation in simulated coal-fired flue gas. The catalytic mechanism for simultaneous removal of Hg(0) and NO was also investigated. The catalysts were characterized by Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) method. Results indicated that spent TiO2-based SCR-DeNOx catalyst supported Ce-Mn mixed oxides catalyst (CeMn/SCR1) was highly active for Hg(0) oxidation at low temperatures. The Ce1.00Mn/SCR1 performed the best catalytic activities, and approximately 92.80% mercury oxidation efficiency was obtained at 150 °C. The inhibition effect of NH3 on Hg(0) oxidation was confirmed in that NH3 consumed the surface oxygen. Moreover, H2O inhibited Hg(0) oxidation while SO2 had a promotional effect with the aid of O2. The XPS results illustrated that the surface oxygen was responsible for Hg(0) oxidation and NO conversion. Besides, the Hg(0) oxidation and NO conversion were thought to be aided by synergistic effect between the manganese and cerium oxides.

  2. PARAQUAT TOLERANCE3 Is an E3 Ligase That Switches off Activated Oxidative Response by Targeting Histone-Modifying PROTEIN METHYLTRANSFERASE4b.

    Directory of Open Access Journals (Sweden)

    Chao Luo

    2016-09-01

    Full Text Available Oxidative stress is unavoidable for aerobic organisms. When abiotic and biotic stresses are encountered, oxidative damage could occur in cells. To avoid this damage, defense mechanisms must be timely and efficiently modulated. While the response to oxidative stress has been extensively studied in plants, little is known about how the activated response is switched off when oxidative stress is diminished. By studying Arabidopsis mutant paraquat tolerance3, we identified the genetic locus PARAQUAT TOLERANCE3 (PQT3 as a major negative regulator of oxidative stress tolerance. PQT3, encoding an E3 ubiquitin ligase, is rapidly down-regulated by oxidative stress. PQT3 has E3 ubiquitin ligase activity in ubiquitination assay. Subsequently, we identified PRMT4b as a PQT3-interacting protein. By histone methylation, PRMT4b upregulates the expression of APX1 and GPX1, encoding two key enzymes against oxidative stress. On the other hand, PRMT4b is recognized by PQT3 for targeted degradation via 26S proteasome. Therefore, we have identified PQT3 as an E3 ligase that acts as a negative regulator of activated response to oxidative stress and found that histone modification by PRMT4b at APX1 and GPX1 loci plays an important role in oxidative stress tolerance.

  3. PARAQUAT TOLERANCE3 Is an E3 Ligase That Switches off Activated Oxidative Response by Targeting Histone-Modifying PROTEIN METHYLTRANSFERASE4b

    Science.gov (United States)

    Du, Jin; Zhao, Tao-Lan; Wang, Peng-Fei; Zhao, Ping-Xia; Xie, Qi; Cao, Xiao-Feng; Xiang, Cheng-Bin

    2016-01-01

    Oxidative stress is unavoidable for aerobic organisms. When abiotic and biotic stresses are encountered, oxidative damage could occur in cells. To avoid this damage, defense mechanisms must be timely and efficiently modulated. While the response to oxidative stress has been extensively studied in plants, little is known about how the activated response is switched off when oxidative stress is diminished. By studying Arabidopsis mutant paraquat tolerance3, we identified the genetic locus PARAQUAT TOLERANCE3 (PQT3) as a major negative regulator of oxidative stress tolerance. PQT3, encoding an E3 ubiquitin ligase, is rapidly down-regulated by oxidative stress. PQT3 has E3 ubiquitin ligase activity in ubiquitination assay. Subsequently, we identified PRMT4b as a PQT3-interacting protein. By histone methylation, PRMT4b upregulates the expression of APX1 and GPX1, encoding two key enzymes against oxidative stress. On the other hand, PRMT4b is recognized by PQT3 for targeted degradation via 26S proteasome. Therefore, we have identified PQT3 as an E3 ligase that acts as a negative regulator of activated response to oxidative stress and found that histone modification by PRMT4b at APX1 and GPX1 loci plays an important role in oxidative stress tolerance. PMID:27676073

  4. Effect of water vapor on evolution of a thick Pt-layer modified oxide on the NiCoCrAl alloy at high temperature

    Science.gov (United States)

    Song, Peng; He, Xuan; Xiong, Xiping; Ma, Hongqing; Song, Qunling; Lü, Jianguo; Lu, Jiansheng

    2018-03-01

    To investigate the effect of water vapor on the novel Pt-containing oxide growth behavior, Pt-addition within the oxide layer on the surface of NiCoCrAl coating and furnace cycle tests were carried out at 1050 °C in air and air plus water vapor. The thick Pt-containing oxide layer on NiCoCrAl exhibits a different oxidation growth behavior compared to the conventional Pt-diffusion metallic coatings. The Pt-containing oxide after oxidation in air plus water vapor showed a much thicker oxide layer compare to the ones without Pt addition, and also presented a much better coating adhesion. During the oxidation process in air, Pt promotes the spinel (NiCr2O4) formation. However, the Cr2O3 formed in air with water vapor and fixed Pt within the complex oxide layer. The water vapor promoted the Ni and Co outer-diffusion, and combined with Pt to form CoPt compounds on the surface of the NiCoCrAl coating system.

  5. Enhanced antitumor activity of surface-modified iron oxide nanoparticles and an .alpha.-tocopherol derivative in a rat model of mammary gland carcinosarcoma

    Czech Academy of Sciences Publication Activity Database

    Horák, Daniel; Pustovyy, V. I.; Babinskyi, A. V.; Palyvo