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Sample records for acid doped polybenzimidazole

  1. Physicochemical properties of phosphoric acid doped polybenzimidazole membranes for fuel cells

    DEFF Research Database (Denmark)

    He, Ronghuan; Li, Qingfeng; Bach, Anders

    2006-01-01

    Polybenzimidazole (PBI) membranes have been prepared with different molecular weights. The water and acid swelling, mechanical strength,gas permeability and proton conductivity were studied for the pristine and acid doped PBI membranes. When doped with 5 mol of phosphoric acid per mole repeat unit...

  2. Water Uptake and Acid Doping of Polybenzimidazoles as Electrolyte Membranes for Fuel Cells

    DEFF Research Database (Denmark)

    Qingfeng, Li; He, R.; Berg, Rolf W.

    2004-01-01

    Acid-doped polybenzimidazole (PBI) membranes have been demonstrated for fuel cell applications with advanced features such as high operating temperatures, little humidification, excellent CO tolerance, and promising durability. The water uptake and acid doping of PBI membranes have been studied...

  3. Doping phosphoric acid in polybenzimidazole membranes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    He, Ronghuan; Li, Qingfeng; Jensen, Jens Oluf

    2007-01-01

    Polybenzimidazole (PBI) membranes were doped in phosphoric acid solutions of different concentrations at room temperature. The doping chemistry was studied using the Scatchard method. The energy distribution of the acid complexation in polymer membranes is heterogeneous, that is, there are two...

  4. Proton conductivity of phosphoric acid doped polybenzimidazole and its composites with inorganic proton conductors

    DEFF Research Database (Denmark)

    He, Ronghuan; Qingfeng, Li; Gang, Xiao

    2003-01-01

    Phosphoric acid doped polybenzimidazole (PBI) and PBI composite membranes have been prepared in the present work. The PBI composites contain inorganic proton conductors including zirconium phosphate (ZrP), (Zr(HPO4)2·nH2O), phosphotungstic acid (PWA), (H3PW12O40·nH2O) and silicotungstic acid (Si...

  5. Lowering the platinum loading of high temperature polymer electrolyte membrane fuel cells with acid doped polybenzimidazole membranes

    DEFF Research Database (Denmark)

    Fernandez, Santiago Martin; Li, Qingfeng; Jensen, Jens Oluf

    2015-01-01

    Membrane electrode assemblies (MEAs) with ultra-low Pt loading electrodes were prepared for high temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) based on acid doped polybenzimidazole. With no electrode binders or ionomers, the triple phase boundary of the catalyst layer...

  6. Spectrophotometric Analysis of Phosphoric Acid Leakage in High-Temperature Phosphoric Acid-Doped Polybenzimidazole Membrane Fuel Cell Application

    Directory of Open Access Journals (Sweden)

    Seungyoon Han

    2016-01-01

    Full Text Available High-temperature proton exchange membrane fuel cells (HT-PEMFCs utilize a phosphoric acid- (PA- doped polybenzimidazole (PBI membrane as a polymer electrolyte. The PA concentration in the membrane can affect fuel cell performance, as a significant amount of PA can leak from the membrane electrode assembly (MEA by dissolution in discharged water, which is a byproduct of cell operation. Spectrophotometric analysis of PA leakage in PA-doped polybenzimidazole membrane fuel cells is described here. This spectrophotometric analysis is based on measurement of absorption of an ion pair formed by phosphomolybdic anions and the cationoid color reagent. Different color reagents were tested based on PA detection sensitivity, stability of the formed color, and accuracy with respect to the amount of PA measured. This method allows for nondestructive analysis and monitoring of PA leakage during HT-PEMFCs operation.

  7. Phosphoric acid doped polybenzimidazole membranes: Physiochemical characterization and fuel cell applications [PEM fuel cells

    DEFF Research Database (Denmark)

    Qingfeng, Li; Hjuler, Hans Aage; Bjerrum, Niels

    2001-01-01

    A polymer electrolyte membrane fuel cell operational at temperatures around 150-200 degrees C is desirable for fast electrode kinetics and high tolerance to fuel impurities. For this purpose polybenzimidazole (PBI) membranes have been prepared and H/sub 3/PO/sub 4/-doped in a doping range from 30...

  8. Durability Issues of High Temperature Proton Exchange Membrane Fuel Cells Based on Acid Doped Polybenzimidazole Membranes

    DEFF Research Database (Denmark)

    observed under continuous operation with hydrogen and air at 150-160oC, with a fuel cell performance degradation rate of 5-10 µV/h. Improvement of the membrane performance such as mechanical strength, swelling and oxidative stability has achieved by exploring the polymer chemistry, i.e. covalently......To achieve high temperature operation of proton exchange membrane fuel cells (PEMFC), preferably under ambient pressure, phosphoric acid doped polybenzimidazole (PBI) membrane represents an effective approach, which in recent years has motivated extensive research activities with great progress....... As a critical concern, issues of long term durability of PBI based fuel cells are addressed in this talk, including oxidative degradation of the polymer, mechanical failures of the membrane, acid leaching out, corrosion of carbon support and sintering of catalysts particles. Excellent polymer durability has...

  9. Catalyst Degradation in High Temperature Proton Exchange Membrane Fuel Cells Based on Acid Doped Polybenzimidazole Membranes

    DEFF Research Database (Denmark)

    Cleemann, Lars Nilausen; Buazar, F.; Li, Qingfeng

    2013-01-01

    contribution of the membrane degradation to the performance losses during the potential cycling tests. As the major mechanism of the fuel cell performance degradation, the electrochemical active area of the cathodic catalysts showed a steady decrease in the cyclic voltammetric measurements, which was also...... and multi‐walled carbon nanotubes were used as supports for electrode catalysts and evaluated in accelerated durability tests under potential cycling at 150 °C. Measurements of open circuit voltage, area specific resistance and hydrogen permeation through the membrane were carried out, indicating little......Degradation of carbon supported platinum catalysts is a major failure mode for the long term durability of high temperature proton exchange membrane fuel cells based on phosphoric acid doped polybenzimidazole membranes. With Vulcan carbon black as a reference, thermally treated carbon black...

  10. Development and characterization of acid-doped polybenzimidazole/sulfonated polysulfone blend polymer electrolytes for fuel cells

    DEFF Research Database (Denmark)

    Hasiotis, C.; Li, Qingfeng; Deimede, V.

    2001-01-01

    Polymeric membranes from blends of sulfonated polysulfones (SPSF) and polybenzimidazole (PBI) doped with phosphoric acid were developed as potential high-temperature polymer electrolytes for fuel cells and other electrochemical applications. The water uptake and acid doping of these polymeric...... it was found to be higher than 10/sup -2/ S cm/sup -1/. Much improvement in the mechanical strength is observed for the blend polymer membranes, especially at higher temperatures. Preliminary work has demonstrated the feasibility of these polymeric membranes for fuel-cell applications...

  11. Oxidative degradation of acid doped polybenzimidazole membranes and fuel cell durability in the presence of ferrous ions

    DEFF Research Database (Denmark)

    Liao, Jianhui; Yang, Jingshuai; Li, Qingfeng

    2013-01-01

    . In this study effects of phosphoric acid and ferrous ions were investigated by measurements of the weight loss, intrinsic viscosity and size exclusion chromatography (SEC) of the polymer membranes. Ferrous ions resulted in, as expected, catalytic formation of peroxide radicals and hence the accelerated polymer......Phosphoric acid doped polybenzimidazole membranes have been explored as proton exchange membranes for high temperature polymer electrolyte membrane fuel cells. Long-term durability of the membrane is of critical concern and has been evaluated by accelerated degradation tests under Fenton conditions...... degradation in terms of weight loss and molecular weight decrease. The presence of phosphoric acid as an inevitable dopant of the membranes, on the other hand, significantly impeded the membrane degradation by means of metal ion complexing, decreased pH, and acid–base interactions with the amino groups...

  12. The effect of porosity on performance of phosphoric acid doped polybenzimidazole polymer electrolyte membrane fuel cell

    Directory of Open Access Journals (Sweden)

    Celik Muhammet

    2016-01-01

    Full Text Available A polybenzimidazole (PBI based polymer electrolyte fuel cells, which called high temperature polymer electrolyte fuel cells (HT-PEMS, operate at higher temperatures (120-200°C than conventional PEM fuel cells. Although it is known that HT-PEMS have some of the significant advantages as non-humidification requirements for membrane and the lack of liquid water at high temperature in the fuel cell, the generated water as a result of oxygen reduction reaction causes in the degradation of these systems. The generated water absorbed into membrane side interacts with the hydrophilic PBI matrix and it can cause swelling of membrane, so water transport mechanism in a membrane electrode assembly (MEA needs to be well understood and water balance must be calculated in MEA. Therefore, the water diffusion transport across the electrolyte should be determined. In this study, various porosity values of gas diffusion layers are considered in order to investigate the effects of porosity on the water management for two phase flow in fuel cell. Two-dimensional fuel cell with interdigitated flow-field is modelled using COMSOL Multiphysics 4.2a software. The operating temperature and doping level is selected as 160°C and 6.75mol H3PO4/PBI, respectively.

  13. The effect of porosity on performance of phosphoric acid doped polybenzimidazole polymer electrolyte membrane fuel cell

    Science.gov (United States)

    Celik, Muhammet; Genc, Gamze; Elden, Gulsah; Yapici, Huseyin

    2016-03-01

    A polybenzimidazole (PBI) based polymer electrolyte fuel cells, which called high temperature polymer electrolyte fuel cells (HT-PEMS), operate at higher temperatures (120-200°C) than conventional PEM fuel cells. Although it is known that HT-PEMS have some of the significant advantages as non-humidification requirements for membrane and the lack of liquid water at high temperature in the fuel cell, the generated water as a result of oxygen reduction reaction causes in the degradation of these systems. The generated water absorbed into membrane side interacts with the hydrophilic PBI matrix and it can cause swelling of membrane, so water transport mechanism in a membrane electrode assembly (MEA) needs to be well understood and water balance must be calculated in MEA. Therefore, the water diffusion transport across the electrolyte should be determined. In this study, various porosity values of gas diffusion layers are considered in order to investigate the effects of porosity on the water management for two phase flow in fuel cell. Two-dimensional fuel cell with interdigitated flow-field is modelled using COMSOL Multiphysics 4.2a software. The operating temperature and doping level is selected as 160°C and 6.75mol H3PO4/PBI, respectively.

  14. Proton conductivity of phosphoric acid doped polybenzimidazole and its composites with inorganic protontic conductors

    DEFF Research Database (Denmark)

    Li, Qingfeng

    2003-01-01

    contain inorganic protonic conductors including zirconium phosphate (ZrP), (Zr(HPO4)2. nH2O); phosphotungstic acid (PWA), (H3PW12O40. nH2O); and silicotungstic acid (SiWA), (H4SiW12O40 . nH2O). The conductivity of phosphoric acid doped PBI and PBI composite membranes was found to be dependent on the acid...

  15. Acid-doped Polybenzimidazole Membranes as Electrolyte for Fuel Cells Operating Above 100°C

    DEFF Research Database (Denmark)

    Qingfeng, Li; Jensen, Jens Oluf; He, Ronhuan

    2003-01-01

    The technical achievement and challenges for the PEMFC technology based on perfluorosulfonic acid (PFSA) polymer membranes (e.g. Nafion®) are briefly discussed. The newest development in the field is alternative polymer electrolytes for operation above 100°C. As one of the successful approaches...... to high operational temperatures, the development and evaluation of acid doped PBI membranes are reviewed, covering polymer synthesis, membrane casting, acid doping, physiochemical characterization and fuel cell tests. A high temperature PEMFC system operational at up to 200°C is demonstrated with no gas...... humidification and high CO-tolerance up to 10 vol%. This high CO tolerance allows for a direct use of reformed hydrogen without further CO removal, which opens the possibility for an integrated reformer-fuel cell system. The content of this review is to a large extent based on research performed by the authors...

  16. Probing phosphoric acid redistribution and anion migration in polybenzimidazole membranes

    DEFF Research Database (Denmark)

    Becker, Hans; Cleemann, Lars Nilausen; Aili, David

    2017-01-01

    Micro platinum electrodes embedded in a laminated phosphoric acid doped polybenzimidazole membrane are employed to monitor the acid migration during hydrogen pump mode operation. Upon application of a constant current, an immediate ohmic resistance decrease of the membrane near the anode is obser......Micro platinum electrodes embedded in a laminated phosphoric acid doped polybenzimidazole membrane are employed to monitor the acid migration during hydrogen pump mode operation. Upon application of a constant current, an immediate ohmic resistance decrease of the membrane near the anode...... is observed, accompanied by a corresponding increase near the cathode side. This is a direct evidence of migration of the acid anions via the vehicle conducting mechanism, resulting in an accumulation of acid at the anode side and depletion at the cathode side. Both resistances reach a steady state value...

  17. Investigation of electrolyte leaching in the performance degradation of phosphoric acid-doped polybenzimidazole membrane-based high temperature fuel cells

    Science.gov (United States)

    Jeong, Yeon Hun; Oh, Kyeongmin; Ahn, Sungha; Kim, Na Young; Byeon, Ayeong; Park, Hee-Young; Lee, So Young; Park, Hyun S.; Yoo, Sung Jong; Jang, Jong Hyun; Kim, Hyoung-Juhn; Ju, Hyunchul; Kim, Jin Young

    2017-09-01

    Precise monitoring of electrolyte leaching in high-temperature polymer electrolyte membrane fuel cell (HT-PEMFC) devices during lifetime tests is helpful in making a diagnosis of their quality changes and analyzing their electrochemical performance degradation. Here, we investigate electrolyte leaching in the performance degradation of phosphoric acid (PA)-doped polybenzimidazole (PBI) membrane-based HT-PEMFCs. We first perform quantitative analyses to measure PA leakage during cell operation by spectrophotometric means, and a higher PA leakage rate is detected when the current density is elevated in the cell. Second, long-term degradation tests under various current densities of the cells and electrochemical impedance spectroscopy (EIS) analysis are performed to examine the influence of PA loss on the membrane and electrodes during cell performance degradation. The combined results indicate that PA leakage affect cell performance durability, mostly due to an increase in charge transfer resistance and a decrease in the electrochemical surface area (ECSA) of the electrodes. Additionally, a three-dimensional (3-D) HT-PEMFC model is applied to a real-scale experimental cell, and is successfully validated against the polarization curves measured during various long-term experiments. The simulation results highlight that the PA loss from the cathode catalyst layer (CL) is a significant contributor to overall performance degradation.

  18. Performance Degradation Tests of Phosphoric Acid Doped Polybenzimidazole Membrane Based High Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela

    2015-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation of the HT-PEM fuel cell. Continuous tests with pure dry H2...... in the performance during the H2 continuous tests, because of a decrease in the reaction kinetic resistance mainly in the cathode due to the redistribution of PA between the membrane and electrodes. The performance of both single cells decreased in the following tests, with highest performance decay rate...... to the corrosion of carbon support in the catalyst layer and degradation of the PBI membrane. During the continuous test with methanol containing H2 as the fuel the reaction kinetic resistance and mass transfer resistance of both single cells increased, which may be caused by the adsorption of methanol...

  19. In Situ Formed Phosphoric Acid/Phosphosilicate Nanoclusters in the Exceptional Enhancement of Durability of Polybenzimidazole Membrane Fuel Cells at Elevated High Temperatures

    DEFF Research Database (Denmark)

    Zhang, Jin; Aili, David; Bradley, John

    2017-01-01

    Most recently, we developed a phosphotungstic acid impregnated mesoporous silica (PWA-meso-silica) and phosphoric acid doped polybenzimidazole (PA/PBI) composite membrane for use in high temperature fuel cells and achieved exceptional durability under a constant current load of 200 mA cm−2 at 200...

  20. Cross-linked polybenzimidazole membranes for high temperature proton exchange membrane fuel cells with dichloromethyl phosphinic acid as a cross-linker

    DEFF Research Database (Denmark)

    Noye, Pernille; Li, Qingfeng; Pan, Chao

    2008-01-01

    Phosphoric acid doped polybenzimidazole (PBI) membranes have been covalently cross-linked with dichloromethyl phosphinic acid (DCMP). FT-IR measurements showed new bands originating from bonds between the hydrogen bearing nitrogen in the imidazole group of PBI and the CH2 group in DCMP. The produ...

  1. Heterogeneous anion conducting membranes based on linear and crosslinked KOH doped polybenzimidazole for alkaline water electrolysis

    DEFF Research Database (Denmark)

    Aili, David; Hansen, Martin Kalmar; Renzaho, Richard Fulgence

    2013-01-01

    Polybenzimidazole is a highly hygroscopic polymer that can be doped with aqueous KOH to give a material with high ion conductivity in the 10−2Scm−1 range, which in combination with its low gas permeability makes it an interesting electrolyte material for alkaline water electrolysis. In this study...... on their linear counterpart. The technical feasibility of the membranes was evaluated by the preliminary water electrolysis tests showing performance comparable to that of commercially available cell separators with great potential of further improvement....

  2. Gel Electrolytes of Covalent Network Polybenzimidazole and Phosphoric Acid by Direct Casting

    DEFF Research Database (Denmark)

    Kirkebæk, Andreas; Aili, David; Henkensmeier, Dirk

    2017-01-01

    Polybenzimidazole membranes imbibed with phosphoric acid can support high proton conductivity at 120–200 °C, and have therefore emerged as the state-of-the-art electrolytes for fuel cells operating in this temperature range. This work presents a novel and operationally simple methodology for prep......Polybenzimidazole membranes imbibed with phosphoric acid can support high proton conductivity at 120–200 °C, and have therefore emerged as the state-of-the-art electrolytes for fuel cells operating in this temperature range. This work presents a novel and operationally simple methodology...... for preparing mechanically robust covalent network polybenzimidazole membranes containing up to 95 wt% phosphoric acid. Diamino-terminal pre-polymers of different chain lengths are first prepared, followed by addition of a trifunctional carboxylic acid. The crude solutions are cast and subsequently heat treated...

  3. Amino-Functional Polybenzimidazole Blends with Enhanced Phosphoric Acid Mediated Proton Conductivity as Fuel Cell Electrolytes

    DEFF Research Database (Denmark)

    Aili, David; Javakhishvili, Irakli; Han, Junyoung

    2016-01-01

    the phosphoric acid uptake and to obtain mechanically robust membranes, the amino-functional polybenzimidazole derivative is blended with high molecular weight poly [2,2′-(m-phenylene)-5,5′-bisbenzimidazole] at different ratios. Due to the high acid uptake, the homogenous blend membranes show enhanced proton...

  4. Durability study of KOH doped polybenzimidazole membrane for air-breathing alkaline direct ethanol fuel cell

    Science.gov (United States)

    Hou, Hongying; Wang, Suli; Jiang, Qian; Jin, Wei; Jiang, Luhua; Sun, Gongquan

    2011-03-01

    Recently, KOH doped polybenzimidazole (PBI/KOH) membrane has been reported as polymer electrolyte membrane for alkaline direct alcohol fuel cell (ADAFC), but little is known about its durability for ADAFC application. In this paper, the durability of PBI/KOH membrane for air-breathing alkaline direct ethanol fuel cell (ADEFC) is evaluated by means of ex situ and in situ tests. In the case of ex situ durability test, the ionic conductivity of PBI/KOH degrades from initial 0.023 S cm-1 to 0.01 S cm-1 after 100 h, and the degrading rate was 1.3 × 10-4 S cm-1 h-1. As for in situ test, Pt-free air-breathing ADEFC with PBI/KOH membrane can output a peak power density of 16 mW cm-2 at 60 °C. Moreover, it can stably operate for 336 h above 0.3 V. In addition, the interaction between KOH and PBI matrix is also explored by density functional theory study.

  5. Benzimidazole grafted polybenzimidazoles for proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Aili, David; Li, Qingfeng

    2013-01-01

    High molecular weight polybenzimidazole (PBI) was synthesized and grafted with benzimidazole pendant groups. The high molecular weight of PBI resulted in good film-forming properties and superior tensile strength. With a phosphoric acid doping level (ADL) of 13.1, a tensile strength of 16 MPa...

  6. Synthesis of proton conducting sulfonated and phosphonated polybenzimidazoles

    Energy Technology Data Exchange (ETDEWEB)

    Ng, F.; Peron, J.; Salunke, A.; Jones, D.J.; Roziere, J. [Montpellier Univ., Montpellier (France). Lab. des Agregats Moleculaires et Materiaux Inorganiques

    2006-07-01

    A study was conducted in which a new flexible polybenzimidazoles (PBI) was synthesized with a proton conductivity higher than 10-3 S/cm at room temperature, in the absence of any unbound acid. Polybenzimidazoles are particularly robust polymers that are stable under various chemical and thermal environments. It is difficult to achieve direct sulfonation in solution of commercially available PBI, although alternative types of PBI with different solubility properties may be modified in this way. Reaction at high temperature of sulfuric acid-doped PBI membranes results in cross-linked and poorly conducting systems. Although acid-doped PBI membranes have high conductivity, acid loss occurs at temperature and load cycling in an operating fuel cell. Alternative approaches have been suggested, such as direct sulfonation and polycondensation reaction involving building blocks functionalized with protogenic groups that lead to new functionalized polybenzimidazoles with suitable properties for fuel cell application. The membrane microstructure can be modified by controlling the position, number and distribution of the sulfonic (phosphonic) acid groups along the backbone. This also affects membrane swelling and conductivity. This study also investigated the influence of the degree of protogenic group functionalization of polymer and membrane properties such as Tg, film forming properties, membrane water uptake and conductivity, and surface hydrophobic/philic properties. It was concluded that the polymer's conductivity depends on the ion exchange capacity and on the nature of the component diacids that give flexibility to the functionalized polybenzimidazole chains.

  7. Performance of a direct glycerol fuel cell using KOH doped polybenzimidazole as electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Ana P.; Linares, Jose J., E-mail: joselinares@unb.br [Universidade de Brasilia (UnB), Brasilia, DF (Brazil). Instituto de Quimica

    2014-03-15

    This paper studies the influence of the operating variables (glycerol concentration, temperature and feed rate) for a direct glycerol fuel cell fed with glycerol using polybenzimidazole (PBI) impregnated with KOH as electrolyte and Pt/C as catalyst. Temperature displays a beneficial effect up to 75 °C due to the enhanced conductivity and kinetics of the electrochemical reactions. The optimum cell feed corresponds to 1 mol L{sup -1} glycerol and 4 mol L{sup -1} KOH, supplying sufficient quantities of fuel and electrolyte without massive crossover nor mass transfer limitations. The feed rate increases the performance up to a limit of 2 mL min{sup -1}, high enough to guarantee the access of the glycerol and the exit of the products. Finally, the use of binary catalysts (PtRu/C and Pt{sub 3}Sn/C) is beneficial for increasing the cell performance. (author)

  8. A novel amperometric sensor for peracetic acid based on a polybenzimidazole-modified gold electrode

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Mu-Yi, E-mail: huamy@mail.cgu.edu.t [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Chen, Hsiao-Chien [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Tsai, Rung-Ywan [Electronics and Optoelectronics Research Laboratories, Industrial Technology Research Institute, 195, Sec. 4, Chung Hsing Rd., Hsinchu 31040, Taiwan (China); Lin, Yu-Chen [Green Research Center, Department of Chemical and Materials Engineering, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China); Biosensor Group, Biomedical Engineering Research Center, Chang Gung University, 259 Wen-Hwa 1st Rd., Kuei-Shan, Tao-Yuan 33302, Taiwan (China)

    2011-04-30

    We have developed a peracetic acid (PAA) sensor based on a polybenzimidazole-modified gold (PBI/Au) electrode. Fourier transform infrared and X-ray photoelectron spectroscopy indicated that PAA oxidized 69.4% of the imine in PBI to form PBI N-oxide, increasing the electrochemical reduction current during cyclic voltammetry. The chemical oxidation of the PBI/Au electrode by PAA, followed by its electrochemical reduction, allowed PAA to be detected directly and consecutively by assessing its reduction current. The PAA sensor had a broad linear detection range (3.1 {mu}M-1.5 mM) and a rapid response time (3.9 s) at an applied potential of -0.3 V. Potentially interfering substances, such as hydrogen peroxide, acetic acid, and oxygen, had no effect on the ability of the probe to detect PAA, indicating high selectivity of the probe. Furthermore, the detection range, response time, and sensitivity of the sensor could all be improved by modification of the smooth planar electrode surface to a porous three-dimensional configuration. When compared to the analytical characteristics of other PAA sensors operating under optimal conditions, the three-dimensional PBI/Au electrode offers a rapid detection time, a usable linear range, and a relatively low detection limit.

  9. Crosslinked Hexafluoropropylidene Polybenzimidazole Membranes with Chloromethyl Polysulfone for Fuel Cell Applications

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Li, Qingfeng; Cleemann, Lars Nilausen

    2013-01-01

    Hexafluoropropylidene polybenzimidazole (F6PBI) was synthesized with excellent chemical stability and improved solubility. When doped with phosphoric acid, however, the F6PBI membranes showed plastic deformation at elevated temperatures. Further efforts were made to covalently crosslink F6PBI...

  10. High Molecular Weight Polybenzimidazole Membranes for High Temperature PEMFC

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Cleemann, Lars Nilausen; Steenberg, T.

    2014-01-01

    High temperature operation of proton exchange membrane fuel cells under ambient pressure has been achieved by using phosphoric acid doped polybenzimidazole (PBI) membranes. To optimize the membrane and fuel cells, high performance polymers were synthesized of molecular weights from 30 to 94 k......Da with good solubility in organic solvents. Membranes fabricated from the polymers were systematically characterized in terms of oxidative stability, acid doping and swelling, conductivity, mechanical strength and fuel cell performance and durability. With increased molecular weights the polymer membranes...

  11. Polybenzimidazole Membranes Containing Benzimidazole Side Groups for High Temprature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Li, Xueyuan; Xu, Yizin

    2013-01-01

    Polybenzimidazole (PBI) with a high molecular weight of 69,000 was first synthesized. It was afterwards grafted with benzimidazole pendant groups on the backbones. The acid doped benzimidaozle grafted PBI membranes were investigated and characterized including fuel cell tests at elevated temperat......Polybenzimidazole (PBI) with a high molecular weight of 69,000 was first synthesized. It was afterwards grafted with benzimidazole pendant groups on the backbones. The acid doped benzimidaozle grafted PBI membranes were investigated and characterized including fuel cell tests at elevated...... temperatures without humidification. At an acid doping level of 13.1 mol H3PO4 per average molar repeat unit, the PBI membranes with a benzimidazole grafting degree of 10.6% demonstrated a conductivity of 0.15 S cm-1 and a H2-air fuel cell peak power density of 378 mW cm-2 at 180 oC at ambient pressure without...

  12. Oxidative degradation of polybenzimidazole membranes as electrolytes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Liao, J.H.; Li, Qingfeng; Rudbeck, H.C.

    2011-01-01

    Polybenzimidazole membranes imbibed with acid are emerging as a suitable electrolyte material for high-temperature polymer electrolyte fuel cells. The oxidative stability of polybenzimidazole has been identified as an important issue for the long-term durability of such cells. In this paper...... the oxidative degradation of the polymer membrane was studied under the Fenton test conditions by the weight loss, intrinsic viscosity, size exclusion chromatography, scanning electron microscopy and Fourier transform infrared spectroscopy. During the Fenton test, significant weight losses depending...... on the initial molecular weight of the polymer were observed. At the same time, viscosity and SEC measurements revealed a steady decrease in molecular weight. The degradation of acid doped PBI membranes under Fenton test conditions is proposed to start by the attack of hydroxyl radicals at the carbon atom...

  13. High temperature proton exchange membranes based on polybenzimidazole and clay composites for fuel cells

    DEFF Research Database (Denmark)

    Plackett, David; Siu, Ana; Li, Qingfeng

    2011-01-01

    dispersion of modified laponite clay was achieved in polybenzimidazole (PBI) solutions which, when cast and allowed to dry, resulted in homogeneous and transparent composite membranes containing up to 20 wt% clay in the polymer. The clay was organically modified using a series of ammonium......, acid doping and swelling, tensile strength, conductivity and hydrogen permeability as well as by fuel cell tests. For the composite membranes, high acid doping levels were achieved with sufficient mechanical strength and improved dimensional stability or reduced membrane swelling. At an acid doping...... level of 12 mol H3PO4 per monomer unit, proton conductivity as high as 0.12 S cm−1 was obtained at 150 °C and 12% relative humidity. The composite membranes exhibited hydrogen permeability ranging from 0.6 to 1.2 × 10−10 mol cm−1 s−1 bar−1 from 100 to 200 °C, which was five times lower than that of acid...

  14. Phosphoric acid doped membranes based on Nafion®, PBI and their blends – Membrane preparation, characterization and steam electrolysis testing

    DEFF Research Database (Denmark)

    Aili, David; Hansen, Martin Kalmar; Pan, Chao

    2011-01-01

    ® and polybenzimidazole blend membranes was developed. Homogeneous binary membranes covering the whole composition range were prepared and characterized with respect to chemical and physiochemical properties such as water uptake, phosphoric acid doping, oxidative stability, mechanical strength and proton conductivity....... An MEA based on phosphoric acid doped Nafion® was operated at 130 °C at ambient pressure with a current density of 300 mA cm−2 at 1.75 V, with no membrane degradation observed during a test of 90 h. The PBI based MEAs showed better polarization curves (500 mA cm−2 at 1.75 V) but poor durability....

  15. Nanostructured poly(benzimidazole membranes by N-alkylation

    Directory of Open Access Journals (Sweden)

    J. Weber

    2014-01-01

    Full Text Available Modification of poly(benzimidazole (PBI by N-alkylation leads to polymers capable of undergoing microphase separation. Polymers with different amounts of C18 alkyl chains have been prepared. The polymers were analyzed by spectroscopy, thermal analysis, electron microscopy and X-ray scattering. The impact of the amount of alkyl chains on the observed microphase separation was analyzed. Membranes prepared from the polymers do show microphase separation, as evidenced by scattering experiments. While no clear morphology could be derived for the domains in the native state, evidence for the formation of lamellar morphologies upon doping with phosphoric acid is provided. Finally, the proton conductivity of alkyl-modified PBI is compared with that of pure PBI, showing that the introduction of alkyl side chains does not result in significant conductivity changes.

  16. Ionic conducting poly-benzimidazoles; Polybenzimidazoles conducteurs ioniques

    Energy Technology Data Exchange (ETDEWEB)

    Jouanneau, J

    2006-11-15

    Over the last years, many research works have been focused on new clean energy systems. Hydrogen fuel cell seems to be the most promising one. However, the large scale development of this technology is still limited by some key elements. One of them is the polymer electrolyte membrane 'Nafion' currently used, for which the ratio performance/cost is too low. The investigations we carried out during this thesis work are related to a new class of ionic conducting polymer, the sulfonated poly-benzimidazoles (sPBI). Poly-benzimidazoles (PBI) are aromatic heterocyclic polymers well-known for their excellent thermal and chemical stability. Ionic conduction properties are obtained by having strong acid groups (sulfonic acid SO{sub 3}H) on the macromolecular structure. For that purpose, we first synthesized sulfonated monomers. Their poly-condensation with an appropriate non-sulfonated co-monomer yields to sPBI with sulfonation range from 0 to 100 per cent. Three different sPBI structures were obtained, and verified by appropriate analytical techniques. We also showed that the protocol used for the synthesis resulted in high molecular weights polymers. We prepared ionic conducting membrane by casting sPBI solutions on glass plates. Their properties of stability, water swelling and ionic conductivity were investigated. Surprisingly, the behaviour of sPBI was quite different from the other sulfonated aromatic polymers with same amount of SO{sub 3}H, their stability was much higher, but their water swelling and ionic conductivity were quite low. We attributed these differences to strong ionic interactions between the sulfonic acid groups and the basic benzimidazole groups of our polymers. However, we managed to solve this problem synthesizing very highly sulfonated PBI, obtaining membranes with a good balance between all the properties necessary. (author)

  17. High temperature proton exchange membranes based on polybenzimidazoles for fuel cells

    DEFF Research Database (Denmark)

    Li, Qingfeng; Jensen, Jens Oluf; Savinell, Robert F

    2009-01-01

    havebeenmadeincluding spectroscopy,wateruptake and acid doping, thermal and oxidative stability, conductivity, electro-osmoticwater drag, methanol crossover, solubility and permeability of gases, and oxygen reduction kinetics. Related fuel cell technologies such as electrode and MEA fabrication have been developed......To achieve high temperature operation of proton exchange membrane fuel cells (PEMFC), preferably under ambient pressure, acid–base polymer membranes represent an effective approach. The phosphoric acid-doped polybenzimidazole membrane seems so far the most successful system in the field. It has...... in recent years motivated extensive research activities with great progress. This treatise is devoted to updating the development, covering polymer synthesis, membrane casting, physicochemical characterizations and fuel cell technologies. To optimize the membrane properties, high molecular weight polymers...

  18. A Comparative Study of Phosphoric Acid-doped m-PBI Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Perry, Kelly A [ORNL; More, Karren Leslie [ORNL; Payzant, E Andrew [ORNL; Meisner, Roberta A [University of Tennessee (UTK) and Oak Ridge National Laboratory (ORNL); Sumpter, Bobby G [ORNL; Benicewicz, Brian [ORNL

    2014-01-01

    Phosphoric acid (PA)-doped m-polybenzimidazole (PBI) membranes used in high temperature fuel cells and hydrogen pumps were prepared by a conventional imbibing process and a sol-gel fabrication process. A comparative study was conducted to investigate the critical properties of PA doping levels, ionic conductivities, mechanical properties, and molecular ordering. This systematic study found that sol-gel PA-doped m-PBI membranes were able to absorb higher acid doping levels and to achieve higher ionic conductivities than conventionally imbibed membranes when treated in an equivalent manner. Even at similar acid loadings, the sol-gel membranes exhibited higher ionic conductivities. Heat treatment of conventionally imbibed membranes with 29wt% solids caused a significant reduction in mechanical properties; conversely, sol-gel membranes exhibited an enhancement in mechanical properties. From X-ray structural studies and atomistic simulations, both conventionally imbibed and sol-gel membranes exhibited d-spacings of 3.5 and 4.6 , which were tentatively attributed to parallel ring stacking and staggered side-to-side packing, respectively, of the imidazole rings in these aromatic hetercyclic polymers. An anisotropic staggered side-to-side chain packing present in the conventional membranes may be root to the reduction in mechanical properties.

  19. Elastic properties of Nafion, polybenzimidazole and poly [2,5-benzimidazole] membranes determined by AFM tip nano-indentation

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, Esteban A. [Departamento de Fisica de Materia Condensada, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica (CNEA), 1650 San Martin, Buenos Aires (Argentina); Corti, Horacio R. [Departamento de Fisica de Materia Condensada, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica (CNEA), 1650 San Martin, Buenos Aires (Argentina); Instituto de Quimica Fisica de los Materiales, Medio Ambiente y Energia (INQUIMAE), Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellon II, Ciudad Universitaria, 1428 Buenos Aires (Argentina)

    2009-03-15

    The mechanical properties of polybenzimidazole (PBI) and poly [2,5-benzimidazole] (ABPBI) membranes, possible candidates to replace Nafion as proton exchange membranes in direct methanol fuel cells (DMFC), were studied. It was observed by AFM imaging that the morphology of the ABPBI membranes strongly depends on the casting procedure, performed at high temperature from methanesulphonic acid and at low temperature from formic acid. The elastic moduli of the undoped and phosphoric acid doped membranes were determined using the AFM force spectroscopy technique and the differences observed with doped and undoped PBI and Nafion membranes, were discussed in terms of the electrostatic and swelling forces between polymer chains. The analysis of the force curves indicates differences in the mechanical behavior of doped PBI and ABPBI membranes compared to Nafion, which could have practical consequences on the stability of the membrane electrode assemblies. (author)

  20. meta-PBI/methylated PBI-OO blend membranes for acid doped HT PEMFC

    DEFF Research Database (Denmark)

    Cho, Hyeongrae; Hur, Eun; Henkensmeier, Dirk

    2014-01-01

    Methylation of polybenzimidazole leads to positively charged polymer backbones, and moveable anions. Ion exchange of methylated PBI-OO in phosphoric acid (PA) shows that the resulting polymers dissolve. meta-PBI, however, absorbs about 400wt% PA while remaining a self supported membrane. We...... investigate the properties of blend membranes, employing meta-PBI for mechanical integrity and methylated PBI-OO for high PA uptake and resulting proton conductivity. While small additions of PBI-OO decrease the tensile strength of blend membranes (58MPa for 10% PBI-OO), further addition leads to an increase......, and 50% blend membranes show again a tensile strength of 74MPa, just 3MPa lower than pure meta-PBI membranes. Thermal stability of iodide exchanged blend membranes appears to be remarkably high, probably because cleaved iodomethane does not evaporate but methylates meta-PBI. PA concentration in doped...

  1. High temperature polybenzimidazole membrane electrode assemblies using pyridine-polybenzimizazole as catalyst layer binder

    Science.gov (United States)

    Su, Po-Hao; Cheng, Joy; Li, Jia-Fen; Liao, Yi-Hsiang; Yu, T. Leon

    2014-08-01

    We synthesize four pyridine-polybenzimidazoles (PyPBIs) and one polybenzimidazole (PBI) from a tetramin monomer (i.e., 3,3‧-diamino benzidine (DABZ)) and two dicarboxylic acid monomers (i.e., isophthalic acid (IPA) and 2,6-pyridinedicarboxylic acid (PyA)) with PyA/IPA molar ratios of 6/4 (i.e., PyPBI-64), 5/5 (i.e., PyPBI-55), 4/6 (i.e., PyPBI-46), 3/7 (i.e., PyPBI-37), and 0/1 (i.e., PBI-11). The PyPBIs and PBI with molecular weight of ∼1.0-1.3 × 10-4 g mol-1 are used as Pt-C (Pt on carbon support) binders for fabricating gas diffusion electrodes (GDEs) and are doped with H3PO4 to prepare membrane electrode assemblies (MEAs). We demonstrate that both the H3PO4 loading of the GDE and the fuel cell performance of the MEA at 160 °C with unhumidified H2/O2 fuel increase with the increase of PyA monomer content of the PyPBI (or PBI) binder in the GDEs according to the sequence of PBI-11 cell performance.

  2. Precursor polymer compositions comprising polybenzimidazole

    Energy Technology Data Exchange (ETDEWEB)

    Klaehn, John R.; Peterson, Eric S.; Orme, Christopher J.

    2015-07-14

    Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

  3. Acid-doped polymer nanofiber framework: Three-dimensional proton conductive network for high-performance fuel cells

    Science.gov (United States)

    Tanaka, Manabu; Takeda, Yasushi; Wakiya, Takeru; Wakamoto, Yuta; Harigaya, Kaori; Ito, Tatsunori; Tarao, Takashi; Kawakami, Hiroyoshi

    2017-02-01

    High-performance polymer electrolyte membranes (PEMs) with excellent proton conductivity, gas barrier property, and membrane stability are desired for future fuel cells. Here we report the development of PEMs based on our proposed new concept ;Nanofiber Framework (NfF).; The NfF composite membranes composed of phytic acid-doped polybenzimidazole nanofibers (PBINf) and Nafion matrix show higher proton conductivity than the recast-Nafion membrane without nanofibers. A series of analyses reveal the formation of three-dimensional network nanostructures to conduct protons and water effectively through acid-condensed layers at the interface of PBINf and Nafion matrix. In addition, the NfF composite membrane achieves high gas barrier property and distinguished membrane stability. The fuel cell performance by the NfF composite membrane, which enables ultra-thin membranes with their thickness less than 5 μm, is superior to that by the recast-Nafion membrane, especially at low relative humidity. Such NfF-based high-performance PEM will be accomplished not only by the Nafion matrix used in this study but also by other polymer electrolyte matrices for future PEFCs.

  4. Polybenzimidazole/Mxene composite membranes for intermediate temperature polymer electrolyte membrane fuel cells

    Science.gov (United States)

    Fei, Mingming; Lin, Ruizhi; Deng, Yuming; Xian, Hongxi; Bian, Renji; Zhang, Xiaole; Cheng, Jigui; Xu, Chenxi; Cai, Dongyu

    2018-01-01

    This report demonstrated the first study on the use of a new 2D nanomaterial (Mxene) for enhancing membrane performance of intermediate temperature (>100 °C) polymer electrolyte membrane fuel cells (ITPEMFCs). In this study, a typical Ti3C2T x -MXene was synthesized and incorporated into polybenzimidazole (PBI)-based membranes by using a solution blending method. The composite membrane with 3 wt% Ti3C2T x -MXene showed the proton conductivity more than 2 times higher than that of pristine PBI membrane at the temperature range of 100 °C–170 °C, and led to substantial increase in maximum power density of fuel cells by ∼30% tested at 150 °C. The addition of Ti3C2T x -MXene also improved the mechanical properties and thermal stability of PBI membranes. At 3 wt% Ti3C2T x -MXene, the elongation at break of phosphoric acid doped PBI remained unaffected at 150 °C, and the tensile strength and Young’s modulus was increased by ∼150% and ∼160%, respectively. This study pointed out promising application of MXene in ITPEMFCs.

  5. Polybenzimidazole block copolymers for fuel cell: synthesis and studies of block length effects on nanophase separation, mechanical properties, and proton conductivity of PEM.

    Science.gov (United States)

    Maity, Sudhangshu; Jana, Tushar

    2014-05-14

    A series of meta-polybenzimidazole-block-para-polybenzimidazole (m-PBI-b-p-PBI), segmented block copolymers of PBI, were synthesized with various structural motifs and block lengths by condensing the diamine terminated meta-PBI (m-PBI-Am) and acid terminated para-PBI (p-PBI-Ac) oligomers. NMR studies and existence of two distinct glass transition temperatures (Tg), obtained from dynamical mechanical analysis (DMA) results, unequivocally confirmed the formation of block copolymer structure through the current polymerization methodology. Appropriate and careful selection of oligomers chain length enabled us to tailor the block length of block copolymers and also to make varieties of structural motifs. Increasingly distinct Tg peaks with higher block length of segmented block structure attributed the decrease in phase mixing between the meta-PBI and para-PBI blocks, which in turn resulted into nanophase segregated domains. The proton conductivities of proton exchange membrane (PEM) developed from phosphoric acid (PA) doped block copolymer membranes were found to be increasing substantially with increasing block length of copolymers even though PA loading of these membranes did not alter appreciably with varying block length. For example when molecular weight (Mn) of blocks were increased from 1000 to 5500 then the proton conductivities at 160 °C of resulting copolymers increased from 0.05 to 0.11 S/cm. Higher block length induced nanophase separation between the blocks by creating less morphological barrier within the block which facilitated the movement of the proton in the block and hence resulting higher proton conductivity of the PEM. The structural varieties also influenced the phase separation and proton conductivity. In comparison to meta-para random copolymers reported earlier, the current meta-para segmented block copolymers were found to be more suitable for PBI-based PEM.

  6. Performance Evaluation of Polybenzimidazole for Potential Aerospace Applications

    NARCIS (Netherlands)

    Iqbal, H.M.S.

    2014-01-01

    With the increasing use of polymer based composite materials, there is an increasing demand of polymeric resins with high glass transition temperature, high thermal stability and excellent mechanical properties at high temperature. Polybenzimidazole (PBI) is a recently emerged high performance

  7. A Quaternary Polybenzimidazole Membrane for Intermediate Temperature Polymer Electrolyte Membrane Fuel Cells

    DEFF Research Database (Denmark)

    Xu, C.; Scott, K.; Li, Qingfeng

    2013-01-01

    A quaternary ammonium polybenzimidazole (QPBI) membrane was synthesized for applications in intermediate temperature (100–200 °C) hydrogen fuel cells. The QPBI membrane was imbibed with phosphoric acid to provide suitable proton conductivity. The proton conductivity of the membrane was 0.051 S cm–1...... at 150 °C with the PA acid loading level of 3.5 PRU (amount of H3PO4 per repeat unit of polymer QPBI). The QPBI membrane was characterized in terms of composition, structure and morphology by NMR, FTIR, SEM, and EDX. The fuel cell performance with the membrane gave peak power densities of 440 and 240 m...

  8. Invited: A Stability Study of Alkali Doped PBI Membranes for Alkaline Electrolyzer Cells

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Aili, David; Hansen, Martin Kalmar

    2014-01-01

    electrolyte. The system has been quite successful with good oxygen kinetics, but the electrolyte suffers from carbonization when operated in normal CO2containing air and this has limited the application to space technology and similar niches. The alkaline electrolyzer on the other hand has been the state...... demonstrated; in contrast it is typically about an order of magnitude lower, which is insufficient [1]. The aromatic fluorine free polymer polybenzimidazole (PBI) has been very successful as a high temperature fuel cell membrane when doped with phosphoric acid [2] and it has been shown by Xing and Savadogo [3...

  9. Anti-corrosive performance of electropolymerized phosphomolybdic acid doped PANI coating on 304SS

    Science.gov (United States)

    Gao, Yangzhi; Syed, Junaid Ali; Lu, Hongbin; Meng, Xiangkang

    2016-01-01

    A phosphomolybdic acid doped polyaniline (PANI) anti-corrosive coating was synthesized on stainless steel (304SS) by electropolymerization. The combination of phosphoric acid de-doping and phosphomolybdic acid re-doping processes leads to the direct and quick deposition of PANI-coating on 304SS without any residual oxidant impurities. The corrosion resistance of the coating was evaluated in 1 M H2SO4 solution by electrochemical techniques. The doping of phosphomolybdic acid enhances the corrosion resistance provided by the coating. The phosphomolybdic acid re-doped coating has a high Rt of 1999 Ω cm2 in comparison with the phosphoric acid doped and re-doped coatings. The increase in corrosion resistance is due to the presence of phosphomolybdic acid that promotes the formation of oxides which not only fill the pores in the PANI coating but also forms an interfacial oxide layer and hence block the corrosion of 304SS in acidic medium.

  10. Oxidative polycondensation of benzimidazole using NaOCl: Synthesis, characterization, optical, thermal and electrical properties of polybenzimidazoles

    Science.gov (United States)

    Anand, Siddeswaran; Muthusamy, Athianna; Dineshkumar, Sengottuvelu; Chandrasekaran, J.

    2017-11-01

    A series of polybenzimidazole polymers, poly-2-(1H-benzo[d] imidazole-2-yl) phenol (PBIP2), poly-3-(1H-benzo[d] imidazole-2-yl) phenol (PBIP3) and poly-4-(1H-benzo[d] imidazole-2-yl) phenol (PBIP4) were synthesized by oxidative polycondensation of benzimidazole monomers 2-(1H-benzo [d] imidazole-2-yl) phenol (BIP2), 3-(1H-benzo [d] imidazole-2-yl) phenol (BIP3) and 4-(1H-benzo [d] imidazole-2-yl) phenol (BIP4). The structure of benzimidazoles monomers and polybenzimidazoles (PBI) were confirmed by various spectroscopic techniques. The quantum theoretical calculations of band gap energy values of monomers were done with DFT and are compared with its optical band gap energy values. Fluorescence spectra of these compounds showed maximum emission in blue region. The electrical conductivity of PBIs was measured by four-point probe technique and showed good electrical response on iodine doping and conductivity increases with increase iodine doping time. The differences in conductivities among the three PBIs are in accordance with the charge density on imidazole nitrogens calculated by Huckel method. The high carbines residue (∼40%) at 500 °C in thermo gravimetric analysis shows that the PBIs are having reasonably good thermal stability. Polymers have recorded high dielectric constant at low applied frequency of 50 Hz at 393 K. The I-V characteristics of polybenzimidazoles p-n diodes showed rectifying nature with a typical forward to reverse current in the range -4 to 4 V. The high n values are caused by non homogeneities and effect of series resistance.

  11. The Electrochemical Behavior of Phosphoric-Acid-Doped Poly(perfluorosulfonic Acid) Membranes

    DEFF Research Database (Denmark)

    Aili, David; Savinell, Robert F; Jensen, Jens Oluf

    2014-01-01

    Highly conductive phosphoric-acid-doped poly(perfluorosulfonic acid) membranes have long been known to malfunction in fuel cells. This is investigated and found to be due to failure of the anode, in which a limiting current is observed in the very low current-density range. It is proposed...... that the strongly acidic sulfonic acid groups protonate the phosphoric acid under anhydrous conditions, forming excess proton defects that are involved in proton conduction by means of the vehicle mechanism. The slow back-diffusion of phosphoric acid molecules as proton carriers thus limits the long...

  12. Long-term durability of HT-PEM fuel cells based on thermally cross-linked polybenzimidazole

    Science.gov (United States)

    Søndergaard, Tonny; Cleemann, Lars Nilausen; Becker, Hans; Aili, David; Steenberg, Thomas; Hjuler, Hans Aage; Seerup, Larisa; Li, Qingfeng; Jensen, Jens Oluf

    2017-02-01

    Long-term durability of high temperature polymer electrolyte membrane fuel cells based on thermally cross-linked polybenzimidazole membranes was studied and compared with reference membranes based on linear polybenzimidazole. The test was conducted at 160 °C under constant load currents of 200 mA cm-2 for periods of 1000, 4400, and 13,000 h. Extensive beginning-of-life (BoL) and end-of-test (EoT) characterisation was carried out, and disturbance of the steady state operated cells was minimised by limiting in-line diagnostics to the low-invasive technique of electrochemical impedance spectroscopy (EIS). Up until the operating time of 9200 h, the cell equipped with the cross-linked membrane showed an average degradation rate of 0.5 μV h-1, compared to 2.6 μV h-1 for the reference membrane, though parallel tests for a shorter period of time showed deviations, likely due to malfunctioning contact between layers or cell components. For the full test period of 13,000 h, the average voltage decay rate was about 1.4 and 4.6 μV h-1 for cells equipped with cross-linked and linear polybenzimidazole membranes, respectively. EIS and post-test analysis revealed that the cross-linked membrane showed better stability in terms of area specific resistance due to improved acid retention characteristics.

  13. Electrical conductivity and thermopower of phosphoric acid doped polyaniline

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, C.O. [Korea Kumho Petrochem. Co., Taejon (Korea, Republic of). Chem. Labs.; Kim, J.H. [Korea Kumho Petrochem. Co., Taejon (Korea, Republic of). Chem. Labs.; Sung, H.K. [Korea Kumho Petrochem. Co., Taejon (Korea, Republic of). Chem. Labs.; Lee, H. [Korea Kumho Petrochem. Co., Taejon (Korea, Republic of). Chem. Labs.

    1997-01-01

    Electrical transport properties of phosphoric acid doped polyaniline are investigated by the measurements of low temperature conductivity and thermopower. Samples were prepared by chemical polymerization of aniline in aqueous solution of phosphoric acid at various ratios of acid to aniline (Z). The conductivity at room temperature increases from 3 S/cm to 40 S/cm, and the thermopower increases from +0.2 {mu}V/K to +7.6 {mu}V/K, as the ratio Z varies from 1 to 6. The low temperature conductivity follows variable range hopping (VRH) temperature dependence, ln {sigma} {proportional_to} -(T{sub 0}/T){sup x}, where VRH exponent systematically changes from x = 1/2 to 1/4. The thermopower changes from U-shape to linear temperature dependence as the ratio Z increases. The systematic variation of transport data was analyzed by considering heterogeneous contributions from metallic transport and VRH process in disordered polymeric system. (orig.)

  14. Ammonia gas sensing behavior of tanninsulfonic acid doped polyaniline-TiO₂ composite

    National Research Council Canada - National Science Library

    Bairi, Venu Gopal; Bourdo, Shawn E; Sacre, Nicolas; Nair, Dev; Berry, Brian C; Biris, Alexandru S; Viswanathan, Tito

    2015-01-01

    .... A tanninsulfonic acid doped polyaniline (TANIPANI)-titanium dioxide nanocomposite was synthesized by an in situ polymerization of aniline in the presence of tanninsulfonic acid and titanium dioxide nanoparticle...

  15. Study of vibrational spectra of polyaniline doped with sulfuric acid and phosphoric acid.

    Science.gov (United States)

    Arora, M; Luthra, V; Singh, R; Gupta, S K

    2001-01-01

    Vibrational spectra of insulator emeraldine base (EB) form of polyaniline and electrical conductive sulfuric acid- and phosphoric acid-doped emeraldine salts (ES) were studied in the region of 4000-400 cm(-1) at ambient temperature by Fourier transform infrared spectroscopy. Infrared transmittance spectra of EB and ES were investigated to understand the bonding behavior of different organic and inorganic groups present in the polymeric chains and their structural variations on protonation by sulfate or phosphate ion inclusion in the polymer salt network. These studies revealed the para-coupling of deformed disubstituted benzenoid (B) and quinoid (Q) rings with ends capped predominantly by (B4Q1) units. The deformation of B and Q rings was confirmed by the appearance of many weak bands, very weak bands, and satellite structures in strong transmittance peaks of polymeric chain-constituting groups. Protonation takes place at the nitrogen sites of Q rings and forms semiquinone radical ions in ES. The vibrational bands pertaining to B rings, Q rings, B4Q1 units, semiquinone segment, sulfate ions, and phosphate ions were observed and assigned from these measurements. The shift in peak position of some bands with gain or loss in intensity and appearance of some new bands were observed in sulfuric acid- and phosphoric acid-doped ES spectra. These variations are attributed to the formation of new structural groups in ES on protonation and a change in crystalline field by sulfate and phosphate ion doping for crosslinking the polymeric chains.

  16. Quartz crystal microbalance and spectroscopy measurements for acid doping in polyaniline films

    Directory of Open Access Journals (Sweden)

    Mohamad M Ayad and Eman A Zaki

    2008-01-01

    Full Text Available We investigated the doping of thin polyaniline (PANI films, prepared by the chemical oxidation of aniline, with different acids. The initial step in the investigation is the preparation of PANI films from aqueous hydrochloric acid solution. This is followed by dedoping with ammonia to obtain a PANI base, which is subsequently doped with strong acids (e.g. hydrochloric, sulfuric, phosphoric and trichloroacetic acids and with a weak acid (acetic acid. The dopant weight fraction (w, which is connected with the gain of mass during the doping of PANI, was determined in situ using a quartz crystal microbalance (QCM. The behavior of PANI upon doping with different anions derived from strong acids indicates that both proton and the anion uptake into the polymer chains occur sharply, rapidly, completely, and reversibly. However the uptake in the case in acetic acid is characterized by slow diffusion. The doping was studied at different concentrations of acetic acid. A second cycle of dedoping–redoping was also performed. The kinetics of the doping reaction is dominated by Fickian diffusion kinetics. The diffusion coefficients (D of the dopant ions into the PANI chains were determined using the QCM and by UV–Vis absorption spectroscopy in the range of (0.076–1.64× 10−15 cm2 s−1. It was found that D in the second cycle of doping is larger than that evaluated from the first cycle of doping for high concentrations of acetic acid. D for the diffusion and for the dopant ion expulsion from the PANI chains was also determined during the redoping process. It was found that D for acetic acid ions in the doping process is larger than that calculated for the dedoping process.

  17. Exceptionally crystalline and conducting acid doped polyaniline films by level surface assisted solution casting approach

    Energy Technology Data Exchange (ETDEWEB)

    Puthirath, Anand B.; Varma, Sreekanth J.; Jayalekshmi, S., E-mail: jayalekshmi@cusat.ac.in [Division for Research in Advanced Materials, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682022 (India); Methattel Raman, Shijeesh [Nanophotonic and Optoelectronic Devices Laboratory, Department of Physics, Cochin University of Science and Technology, Cochin, Kerala 682022 (India)

    2016-04-18

    Emeraldine salt form of polyaniline (PANI) was synthesized by chemical oxidative polymerisation method using ammonium persulfate as oxidant. Resultant emeraldine salt form of PANI was dedoped using ammonia solution and then re-doped with camphor sulphonic acid (CSA), naphthaline sulphonic acid (NSA), hydrochloric acid (HCl), and m-cresol. Thin films of these doped PANI samples were deposited on glass substrates using solution casting method with m-cresol as solvent. A level surface was employed to get homogeneous thin films of uniform thickness. Detailed X-ray diffraction studies have shown that the films are exceptionally crystalline. The crystalline peaks observed in the XRD spectra can be indexed to simple monoclinic structure. FTIR and Raman spectroscopy studies provide convincing explanation for the exceptional crystallinity observed in these polymer films. FESEM and AFM images give better details of surface morphology of doped PANI films. The DC electrical conductivity of the samples was measured using four point probe technique. It is seen that the samples also exhibit quite high DC electrical conductivity, about 287 S/cm for CSA doped PANI, 67 S/cm for NSA doped PANI 65 S/cm for HCl doped PANI, and just below 1 S/cm for m-cresol doped PANI. Effect of using the level surface for solution casting is studied and correlated with the observed crystallinity.

  18. Controlling the optical properties of polyaniline doped by boric acid particles by changing their doping agent and initiator concentration

    Science.gov (United States)

    Cabuk, Mehmet; Gündüz, Bayram

    2017-12-01

    In this study, polyaniline doped by boric acid (PAni:BA) conducting polymers were chemically synthesized by oxidative polymerization method using (NH4)2S208 (APS) as initiator. Pani:BA conducting polymers were synthesized by using two different APS/aniline molar ratios as 1:1 and 2:1. Their results were compared with PAni doped by HCl (PAni) conducting polymer. Structural properties of the PAni, PAni:BA (1:1) and PAni:BA (2:1) conducting polymers were characterized by using FTIR, SEM, TGA, particle size and apparent density measurements. Effects of doping agents and initiator concentrations on optical properties were investigated in detail. The optoelectronic parameters such as absorption band edge, molar extinction coefficient, direct allowed band gap, refractive index, optical conductance and electrical conductance of the PAni, PAni:BA (1:1) and PAni:BA (2:1) were determined. The absorption band edge and direct allowed band gap of PAni were decreased with doping BA and increasing APS ratio. Also, the refractive index values of the materials were calculated from experimental results and compared with obtained results from Moss, Ravindra, Herve-Vandamme, Reddy and Kumar-Singh relations.

  19. Molecular modeling of protonic acid doping of emeraldine base polyaniline for chemical sensors

    NARCIS (Netherlands)

    Chen, X.; Yuan, C.A.; Wong, C.K.Y.; Ye, H.; Leung, S.Y.Y.; Zhang, G.

    2012-01-01

    We proposed a molecular modeling methodology to study the protonic acid doping of emeraldine base polyaniline which can used in gas detection. The commercial forcefield COMPASS was used for the polymer and protonic acid molecules. The molecular model, which is capable of representing the polyaniline

  20. Phosphoric acid doped AB-PBI membranes and its applications in high temperature PEMFC

    DEFF Research Database (Denmark)

    He, Ronghuan; Qingfeng, Li; Bjerrum, Niels

    2005-01-01

    Poly(2,5-benzimidazole) (ab-PBI) was prepared from 3,4-diaminobenzoic acid via a polymerisation reaction. The obtained polymer exhibits excellent thermal stability in a temperature range ….. The membrane of ab-PBI when doped with phosphoric acid at room temperaturepresents high proton conductivity...

  1. Hydroxyl pyridine containing polybenzimidazole membranes for proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Xu, Yixin; Zhou, Lu

    2013-01-01

    at 180°C without humidifying. In addition, an improved tensile modulus at elevated temperatures was observed for acid doped OHPyPBI membranes. Fuel cell tests demonstrated the technical feasibility of acid doped OHPyPBI membranes for high temperature proton exchange membrane fuel cells. © 2013 Elsevier B.V....

  2. Nickel embedded in N-doped porous carbon for the hydrogenation of nitrobenzene to p-aminophenol in sulphuric acid.

    Science.gov (United States)

    Wang, Tao; Dong, Zhen; Fu, Teng; Zhao, Yanchao; Wang, Tian; Wang, Yongzheng; Chen, Yi; Han, Baohang; Ding, Weiping

    2015-12-28

    An acid-resistant catalyst composed of nickel embedded in N-doped porous carbon is developed for the catalytic hydrogenation of nitrobenzene (NB) to p-aminophenol (PAP). The catalyst, due to a special electron donation from nickel to the N-doped porous carbon, shows an excellent catalytic performance and stability in sulphuric acid solution.

  3. Modulation of the acidity of niobic acid by ion-doping: Effects of nature and amount of the dopant ions

    Energy Technology Data Exchange (ETDEWEB)

    Carniti, Paolo [Dipartimento di Chimica, Università degli Studi di Milano (UNIMI), Milano (Italy); Gervasini, Antonella, E-mail: antonella.gervasini@unimi.it [Dipartimento di Chimica, Università degli Studi di Milano (UNIMI), Milano (Italy); Marzo, Matteo [Dipartimento di Chimica, Università degli Studi di Milano (UNIMI), Milano (Italy); Auroux, Aline [Université Lyon 1, CNRS, UMR 5256, (IRCELYON), Villeurbanne (France)

    2013-09-10

    Highlights: ► Mitigation of the surface acidity of niobic acid was pursued by K-, Ba-, and Nd-doping. ► Thermal techniques of study were effective for the acidity study. ► The nature of the dopant influences the effectiveness of the acidity tuning of niobic acid. ► The acidity of the doped surfaces decreased with increasing the dopant species added to niobic acid. ► The samples showed different acidity when measured in gas–solid phase (intrinsic acidity) and water (effective acidity). - Abstract: The acidity of niobic acid (NBO) has been successfully mitigated and tuned by addition of K{sup +}, Ba{sup 2+} and Nd{sup 3+} dopant species in amounts from 1 to 15 atom nm{sup −2}. The characterization of the intrinsic acid properties of the samples was performed by adsorption of NH{sub 3} in a volumetric–microcalorimetric coupled line and by temperature programmed desorption (TPD) of 2-phenylethylamine in a thermogravimetric apparatus. The K-dopant was more effective in decreasing the acidity of niobic acid than the Ba- and Nd-dopants. Complementary measurements of the effective acidity of the samples in water by base titrations with 2-phenylethylamine completed the study and revealed a different picture of the effect of the three dopants on the NBO acidity in water. All the results indicated that the K-dopant targeted more selectively the Brønsted acid sites, acting as an ion-exchanger, while Ba- and Nd-species predominantly acted on the Lewis acid sites of the NBO surface.

  4. Superior acidic catalytic activity and stability of Fe-doped HTaWO6 nanotubes

    KAUST Repository

    Liu, He

    2017-07-26

    Fe-doped HTaWO6 (H1-3xFexTaWO6, x = 0.23) nanotubes as highly active solid acid catalysts were prepared via an exfoliation-scrolling-exchange process. The specific surface area and pore volume of undoped nanotubes (20.8 m2 g-1, 0.057 cm3 g-1) were remarkably enhanced through Fe3+ ion-exchange (>100 m2 g-1, 0.547 cm3 g-1). Doping Fe ions into the nanotubes endowed them with improved thermal stability due to the stronger interaction between the intercalated Fe3+ ions and the host layers. This interaction also facilitated the preservation of effective Brønsted acid sites and the generation of new acid sites. The integration of these functional roles resulted in Fe-doped nanotubes with high acidic catalytic activities in the Friedel-Crafts alkylation of anisole and the esterification of acetic acid. Facile accessibility to active sites, generation of effective Brønsted acid sites, high stability of the tubular structure and strong acid sites were found to synergistically contribute to the excellent acidic catalytic efficiency. Additionally, the activity of cycled nanocatalysts can be easily recovered through annealing treatment.

  5. Effect of chloride impurities on the performance and durability of polybenzimidazole-based high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Ali, Syed Talat; Li, Qingfeng; Pan, Chao

    2011-01-01

    . The performance loss was recovered when switching from the HCl solution back to pure water in the air humidifier. Under an accelerated aging performance test conducted through potential cycling between 0.9 V and 1.2 V, the PBI-based fuel cell initially containing 0.5 NaCl mg cm−2 on the cathode catalyst layer......The effect of chloride as an air impurity and as a catalyst contaminant on the performance and durability of polybenzimidazole (PBI)-based high temperature proton exchange membrane fuel cell (HT-PEMFC) was studied. The ion chromatographic analysis reveals the existence of chloride contaminations...... temperatures in 85% phosphoric acid containing chloride ions showed both increase in oxidation and reduction current densities. The fuel cell performance, i.e. the current density at a constant voltage of 0.4 V and 0.5 V was found to be degraded as soon as HCl was introduced in the air humidifier...

  6. Electropolymerization of camphorsulfonic acid doped conductive polypyrrole anti-corrosive coating for 304SS bipolar plates

    Science.gov (United States)

    Jiang, Li; Syed, Junaid Ali; Gao, Yangzhi; Zhang, Qiuxiang; Zhao, Junfeng; Lu, Hongbin; Meng, Xiangkang

    2017-12-01

    Conductive polymer coating doped with large molecular organic acid is an alternative method used to protect stainless steel (SS) bipolar plates in proton exchange membrane fuel cells (PEMFCs). However, it is difficult to select the proper doping acid, which improves the corrosion resistance of the coating without affecting its conductivity. In this study, large spatial molecular group camphorsulfonic acid (CSA) doped polypyrrole (PPY) conductive coating was prepared by galvanostatic electropolymerization on 304SS. The electrochemical properties of the coating were evaluated in 0.1 M H2SO4 solution in order to simulate the PEMFC service environment. The results indicate that the coating increased the corrosion potential and shifted Ecorr towards more positive value, particularly the jcorr value of PPY-CSA coated 304SS was dropped from 97.3 to 0.00187 μA cm-2. The long-term immersion tests (660 h) show that the PPY-CSA coating exhibits better corrosion resistance in comparison with the small acid (SO42-) doped PPY-SO42- or PPY/PPY-SO42- coatings. Moreover, the PPY-CSA coating presents low contact resistance and maintains strong corrosion resistance during the prolonged exposure time due to barrier effect and anodic protection.

  7. Molecular modeling of the conductivity changes of the emeraldine base polyaniline due to protonic acid doping

    NARCIS (Netherlands)

    Chen, X.; Yuan, C.A.; Wong, C.K.Y.; Zhang, G.

    2012-01-01

    We propose a molecular modeling strategy, which is capable of predicting the conductivity change of emeraldine base polyaniline polymer due to different degree of protonic acid doping. The method is comprised of two key steps: (1) generating the amorphous unit cells with given number of polymer

  8. Polybenzimidazole-based mixed membranes with exceptional high water vapor permeability and selectivity

    KAUST Repository

    Akhtar, Faheem Hassan

    2017-09-13

    Polybenzimidazole (PBI), a thermal and chemically stable polymer, is commonly used to fabricate membranes for applications like hydrogen recovery at temperatures of more than 300 °C, fuel cells working in a highly acidic environment, and nanofiltration in aggressive solvents. This report shows for the first time use of PBI dense membranes for water vapor/gas separation applications. They showed an excellent selectivity and high water vapor permeability. Incorporation of inorganic hydrophilic titanium-based nano-fillers into the PBI matrix further increased the water vapor permeability and water vapor/N2 selectivity. The most selective mixed matrix membrane with 0.5 wt% loading of TiO2 nanotubes yielded a water vapor permeability of 6.8×104 Barrer and a H2O/N2 selectivity of 3.9×106. The most permeable membrane with 1 wt% loading of carboxylated TiO2 nanoparticles had a 7.1×104 Barrer water vapor permeability and a H2O/N2 selectivity of 3.1×106. The performance of these membranes in terms of water vapor transport and selectivity is among the highest reported ones. The remarkable ability of PBI to efficiently permeate water versus other gases opens the possibility to fabricate membranes for dehumidification of streams in harsh environments. This includes the removal of water from high temperature reaction mixtures to shift the equilibrium towards products.

  9. Synthesis and characterization of Cerium-doped hydroxyapatite/polylactic acid composite coatings on metal substrates

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Qiuhua, E-mail: yuanqiuh@szu.edu.cn; Qin, Caoping; Wu, Jianbo; Xu, Anping; Zhang, Ziqiang; Liao, Junquan; Lin, Songxin; Ren, Xiangzhong; Zhang, Peixin

    2016-10-01

    Ce-doped hydroxyapatite/polylactic acid (HA/PLA) composites serving as implant coatings have rarely been studied by other researchers in recent years. This paper was focused to study the existence of Ce ions in structure, chemical composition and surface morphology of HA and its composite coatings. Ce-doped HA powders were synthesized by chemical precipitation method with different Ce molar fractions (0(pure HA), 0.5 mol%, 1 mol% and 2 mol%). And Ce-doped HA/PLA composite coatings were fabricated for the first time on stainless steel substrates by spin coating technique. The obtained samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) coupled with energy dispersive X-ray detector (EDX), thermo gravimetric-differential thermal analysis (TG-DTA) and X-ray photoelectron spectroscopy (XPS). The results showed that Ce ions were doped into the crystal lattice of apatite successfully. The (Ce + Ca)/P atomic ratios in the doped HA/PLA samples ranged from 1.614 to 1.673, which were very close to the theoretical value of 1.67 for the stoichiometric HA. The addition of PLA could keep metal substrates from catalyzing the decomposition of HA. TG-DTA analysis indicated that Ce-doped HA powder had high thermal stability, and the SEM micrographs revealed that the surface topography of Ce-doped HA/PLA composite coatings was uniform and dense when the Ce molar fraction was 2 mol%. XPS results indicated that the Ce ions doped in HA showed mixed valences of Ce{sup 3+} and Ce{sup 4+}. - Highlights: • Ce-doped HA composite coatings were synthesized by spin-coating technique for the first time. • Ce ions were demonstrated to dope into HA crystal lattice successfully. • The addition of PLA could keep metal substrates from catalyzing the decomposition of HA. • XPS results showed that Ce ions doped in HA have mixed valences of Ce{sup 3+} and Ce{sup 4+}.

  10. New Polymer Electrolyte Membranes Based on Acid Doped PBI For Fuel Cells Operating above 100°C

    DEFF Research Database (Denmark)

    Li, Qingfeng

    2003-01-01

    The technical achievement and challenges for the PEMFC technology based on perfluorosulfonic acid (PFSA) polymer membranes (e.g. Nafion®) are briefly discussed. The newest development for alternative polymer electrolytes for operation above 100°C. As one of the successful approaches to high...... operational temperatures, the development and evaluation of acid doped PBI membranes are reviewed, covering polymer synthesis, membrane casting, acid doping, physiochemical characterization and fuel cell tests....

  11. A comparison study of rhodamine B photodegradation over nitrogen-doped lamellar niobic acid and titanic acid under visible-light irradiation.

    Science.gov (United States)

    Li, Xiukai; Kikugawa, Naoki; Ye, Jinhua

    2009-01-01

    A solid-state reaction method with urea as a nitrogen precursor was used to prepare nitrogen-doped lamellar niobic and titanic solid acids (i.e., HNb(3)O(8) and H(2)Ti(4)O(9)) with different acidities for visible-light photocatalysis. The photocatalytic activities of the nitrogen-doped solid acids were evaluated for rhodamine B (RhB) degradation and the results were compared with those obtained over the corresponding nitrogen-doped potassium salts. Techniques such as XRD, BET, SEM, X-ray photoelectron spectroscopy, and UV-visible diffuse reflectance spectroscopy were adopted to explore the nature of the materials as well as the characteristics of the doped nitrogen species. It was found that the intercalation of the urea precursor helped to stabilize the layered structures of both lamellar solid acids and enabled easier nitrogen doping. The effects of urea intercalation were more significant for the more acidic HNb(3)O(8) sample than for the less acidic H(2)Ti(4)O(9). Compared with the nitrogen-doped KNb(3)O(8) and K(2)Ti(4)O(9) samples, the nitrogen-doped HNb(3)O(8) and H(2)Ti(4)O(9) solid acids absorb more visible light and exhibit a superior activity for RhB photodegradation under visible-light irradiation. The nitrogen-doped HNb(3)O(8) sample performed the best among all the samples. The results of the current study suggest that the protonic acidity of the lamellar solid-acid sample is a key factor that influences nitrogen doping and the resultant visible-light photocatalysis.

  12. Nitrogen-doped zinc oxide thin films biosensor for determination of uric acid.

    Science.gov (United States)

    Jindal, Kajal; Tomar, Monika; Gupta, Vinay

    2013-08-07

    Nitrogen-doped zinc oxide thin films (ZnO:N) have been realized as a potential matrix for the development of a uric acid biosensor. The correlation between the change in property of the ZnO film with N doping concentration and its biosensing response has been studied. The nitrogen dopant in a ZnO film alters its defects profile, thus improving the charge transfer characteristics and resulting in an enhanced peak oxidation current in the cyclic voltammogram in comparison to that of the pure ZnO film. The studies reveal that the bio-electrode based on the nitrogen-doped ZnO thin film matrix exhibits better sensitivity (1.1 mA mM(-1) cm(-2)) with linearity over a wide range (0.05 mM to 1.0 mM) of uric acid concentration. A comparatively low value (0.10 mM) of the Michaelis-Menten constant (Km) indicates high affinity of the immobilized uricase towards uric acid. The proposed ZnO:N thin films matrix-based uric acid-biosensor has good reproducibility, a long shelf-life (20 weeks) and high selectivity.

  13. 3D Polyaniline Architecture by Concurrent Inorganic and Organic Acid Doping for Superior and Robust High Rate Supercapacitor Performance.

    Science.gov (United States)

    Gawli, Yogesh; Banerjee, Abhik; Dhakras, Dipti; Deo, Meenal; Bulani, Dinesh; Wadgaonkar, Prakash; Shelke, Manjusha; Ogale, Satishchandra

    2016-02-12

    A good high rate supercapacitor performance requires a fine control of morphological (surface area and pore size distribution) and electrical properties of the electrode materials. Polyaniline (PANI) is an interesting material in supercapacitor context because it stores energy Faradaically. However in conventional inorganic (e.g. HCl) acid doping, the conductivity is high but the morphological features are undesirable. On the other hand, in weak organic acid (e.g. phytic acid) doping, interesting and desirable 3D connected morphological features are attained but the conductivity is poorer. Here the synergy of the positive quality factors of these two acid doping approaches is realized by concurrent and optimized strong-inorganic (HCl) and weak-organic (phytic) acid doping, resulting in a molecular composite material that renders impressive and robust supercapacitor performance. Thus, a nearly constant high specific capacitance of 350 F g(-1) is realized for the optimised case of binary doping over the entire range of 1 A g(-1) to 40 A g(-1) with stability of 500 cycles at 40 A g(-1). Frequency dependant conductivity measurements show that the optimized co-doped case is more metallic than separately doped materials. This transport property emanates from the unique 3D single molecular character of such system.

  14. Effect of Heat Treatment on Optical Properties of Crosslinkable Azo Chromophore Doped in Poly Amic Acid

    Science.gov (United States)

    Hamedi, S.; Gharavi, A.

    2015-11-01

    In this work, we have studied the optical properties of a crosslinkable poly amic acid containing Disperse Red 1. The thin films were cured at 130, 160 and 195 °C. The structural and optical properties of the doped films were investigated by using UV-VIS spectra, and Prism Coupling techniques. The composite crosslinks during poling rendering it totally insoluble. A r33 of 1.5 pm/v was obtained after poling.

  15. Studies on biphenyl disulphonic acid doped polyanilines: Synthesis ...

    Indian Academy of Sciences (India)

    Particularly, attention has been given on polyaniline (PAni) due to its environmental stability, film forming property with tunable conductivity and commercial viability. ... fonic acid ring-substituted polyanilines (SPAN) (Yue et al. 1991; Wei et al 1996). With respect to the parent poly- mer PAni, substituted polyanilines exhibit ...

  16. Electroactive self-doped poly(amic acid) with oligoaniline and sulfonic acid groups: synthesis and electrochemical properties.

    Science.gov (United States)

    Chi, Maoqiang; Wang, Shutao; Liang, Yuan; Chao, Danming; Wang, Ce

    2014-06-01

    A novel poly(amic acid) with pendant aniline tetramer and sulfonic acid groups (ESPAA) was synthesized by ternary polymerization and characterized by Fourier-transform infrared spectra, ((1))H NMR and gel permeation chromatography. The polymer showed good thermal stability and excellent solubility in the common organic solvents. The electrochemical properties were investigated carefully on a CHI 660A Electrochemical Workstation. The polymer displayed good electroactivity in acid, neutral and even in alkaline solutions (pH=1-10) due to the self-doping effect between aniline tetramer and sulfonic/carboxylic acid groups. It also exhibited satisfactory electrochromic performance with high contrast value, acceptable coloration efficiency and fast switching time in the range of pH=1-9. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Doping Polypyrrole Films with 4-N-Pentylphenylboronic Acid to Enhance Affinity towards Bacteria and Dopamine.

    Science.gov (United States)

    Golabi, Mohsen; Padiolleau, Laurence; Chen, Xi; Jafari, Mohammad Javad; Sheikhzadeh, Elham; Turner, Anthony P F; Jager, Edwin W H; Beni, Valerio

    2016-01-01

    Here we demonstrate the use of a functional dopant as a fast and simple way to tune the chemical affinity and selectivity of polypyrrole films. More specifically, a boronic-functionalised dopant, 4-N-Pentylphenylboronic Acid (PBA), was used to provide to polypyrrole films with enhanced affinity towards diols. In order to prove the proposed concept, two model systems were explored: (i) the capture and the electrochemical detection of dopamine and (ii) the adhesion of bacteria onto surfaces. The chemisensor, based on overoxidised polypyrrole boronic doped film, was shown to have the ability to capture and retain dopamine, thus improving its detection; furthermore the chemisensor showed better sensitivity in comparison with overoxidised perchlorate doped films. The adhesion of bacteria, Deinococcus proteolyticus, Escherichia coli, Streptococcus pneumoniae and Klebsiella pneumoniae, onto the boric doped polypyrrole film was also tested. The presence of the boronic group in the polypyrrole film was shown to favour the adhesion of sugar-rich bacterial cells when compared with a control film (Dodecyl benzenesulfonate (DBS) doped film) with similar morphological and physical properties. The presented single step synthesis approach is simple and fast, does not require the development and synthesis of functional monomers, and can be easily expanded to the electrochemical, and possibly chemical, fabrication of novel functional surfaces and interfaces with inherent pre-defined sensing and chemical properties.

  18. Thermally treated polyaniline/polybenzimidazole blend membranes: structural changes and gas transport properties

    Czech Academy of Sciences Publication Activity Database

    Giel, Verena; Morávková, Zuzana; Peter, Jakub; Trchová, Miroslava

    2017-01-01

    Roč. 537, 1 September (2017), s. 315-322 ISSN 0376-7388 R&D Projects: GA MŠk(CZ) LO1507; GA ČR(CZ) GA16-02787S Institutional support: RVO:61389013 Keywords : polybenzimidazole * polyaniline * thermal treatment Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science Impact factor: 6.035, year: 2016

  19. PEM steam electrolysis at 130 °C using a phosphoric acid doped short side chain PFSA membrane

    DEFF Research Database (Denmark)

    Hansen, Martin Kalmar; Aili, David; Christensen, Erik

    2012-01-01

    Steam electrolysis test with a phosphoric acid doped Aquivion™ membrane was successfully conducted and current densities up to 775 mA cm-2 at 1.8 V was reached at 130 ºC and ambient pressure. A new composite membrane system using a perfluorosulfonic acid membrane (Aquivion™) as matrix and phospho......Steam electrolysis test with a phosphoric acid doped Aquivion™ membrane was successfully conducted and current densities up to 775 mA cm-2 at 1.8 V was reached at 130 ºC and ambient pressure. A new composite membrane system using a perfluorosulfonic acid membrane (Aquivion™) as matrix...

  20. Carbon doping of MgB{sub 2} by toluene and malic-acid-in-toluene

    Energy Technology Data Exchange (ETDEWEB)

    Bohnenstiehl, S.D., E-mail: bohnenstiehl.1@osu.ed [Center for Superconducting and Magnetic Materials, Department of Materials Science and Engineering, Ohio State University, Columbus, OH (United States); Susner, M.A.; Yang, Y.; Collings, E.W.; Sumption, M.D. [Center for Superconducting and Magnetic Materials, Department of Materials Science and Engineering, Ohio State University, Columbus, OH (United States); Rindfleisch, M.A.; Boone, R. [Hyper Tech Research, Inc., 539 Industrial Mile Road, Columbus, OH 43228 (United States)

    2011-02-15

    Research highlights: {yields} Both toluene and malic acid contribute carbon to MgB{sub 2}. {yields} Toluene is more effective than malic acid for transport properties. {yields} Total carbon can be measured by LECO carbon analysis. - Abstract: The decomposition of malic acid (C{sub 4}H{sub 6}O{sub 5}) in the presence of Mg and B was studied using Differential Scanning Calorimetry (DSC) and Thermogravimetric Analysis (TGA) which revealed that malic acid reacted with Mg but not B. Also, the addition of toluene (C{sub 7}H{sub 8}) to dissolve malic acid followed by subsequent drying resulted in no reaction with Mg, indicating that the malic acid had decomposed during the dissolution/drying stage. The total carbon contributed by toluene versus a toluene/5 wt.% malic acid mixture was measured using a LECO CS600 carbon analyzer. The toluene sample contained {approx}0.4 wt.% C while the toluene/malic acid mixture had {approx}1.5 wt.% C, demonstrating that the toluene contributed a significant amount of carbon to the final product. Resistivity measurements on powder-in-tube MgB{sub 2} monofilamentary wires established that the toluene/malic acid doped sample had the highest B{sub c2}. However, the toluene-only sample had the highest transport J{sub c} over most of the magnetic field range (0-9 T), equaled only by that of toluene/malic-acid sample in fields above 9 T.

  1. Acid resistance of erbium-doped yttrium aluminum garnet laser-treated and phosphoric acid-etched enamels.

    Science.gov (United States)

    Kim, Jung-Ho; Kwon, Oh-Won; Kim, Hyung-Il; Kwon, Yong Hoon

    2006-11-01

    To compare the effects of erbium-doped yttrium aluminum garnet (Er:YAG) laser ablation and of phosphoric acid etching on the in vitro acid resistance of bovine enamel. Teeth were polished to make the surface flat. The polished enamel was either etched with 37% phosphoric acid for 30 seconds or ablated with a single 33 J/cm2 pulse from an Er:YAG laser. The control specimens were free from acid etching and laser ablation. Changes in crystal structure, dissolved mineral (calcium [Ca] and phosphorus [P]) contents, and calcium distribution in the enamel subsurface after a pH-cycling process were evaluated. After laser treatment, poor crystal structures improved without forming any new phases, such as tricalcium phosphates. Among the tested enamels, dissolved mineral contents were significantly different (P phosphoric acid-etched enamels had the highest (Ca, 15.90 ppm; P, 7.33 ppm). The reduction rate and reduced depth of calcium content along the subsurface were lowest in Er:YAG laser-treated enamels. The Er:YAG laser-treated enamels are more acid resistant to acid attack than phosphoric acid-etched enamels.

  2. New nanocomposites of polystyrene with polyaniline doped with lauryl sulfuric acid

    Science.gov (United States)

    Pud, A. A.; Nikolayeva, O. A.; Vretik, L. O.; Noskov, Yu. V.; Ogurtsov, N. A.; Kruglyak, O. S.; Fedorenko, E. A.

    2017-08-01

    This work is concentrated on synthesis and investigation of new core-shell nanocomposites of polystyrene (PS) with doped polyaniline (PANI). The latex containing PS nanoparticles with sizes of 15-30 nm was prepared by microemulsion polymerization of styrene in water media. The PS/PANI nanocomposites were synthesized by chemical oxidative polymerization of aniline in the PS latex media in a presence of lauryl sulfuric acid (LSA), which served as both dopant and plasticizer. The real content of PANI in the synthesized nanocomposites was determined by UV-Vis spectroscopy method. The composition of the nanocomposites and oxidation state of the doped polyaniline were characterized by FTIR spectroscopy. The core-shell morphology of the nanocomposite nanoparticles was proved by transmission and scanning electron microscopy. It was found that conductivity and thermal behavior in air of these nanocomposites not only nonlinearly depended on the doped polyaniline content but also were strongly effected both by plasticizing properties of the acid-dopant and presence of the polyaniline shell. A possibility of application of these nanocomposites as sensor materials has been demonstrated.

  3. Superconducting properties of adipic-acid-doped bulk MgB{sub 2} superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Vajpayee, Arpita; Awana, V P S; Kishan, H [Superconductivity and Cryogenics Division, National Physical Laboratory, Dr K S Krishnan Road, New Delhi 110012 (India); Bhalla, G L [Department of Physics and Astrophysics, University of Delhi, New Delhi 110007 (India); Bhobe, P A; Nigam, A K [Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)], E-mail: awana@mail.nplindia.ernet.in

    2009-01-15

    We report the effect of adipic acid (C{sub 6}H{sub 10}O{sub 4}) doping on lattice parameters, microstructure, critical temperature (T{sub c}), current density (J{sub c}) and irreversibility field (H{sub irr}) for an MgB{sub 2} superconductor. Actual carbon (C) substitution level for boron (B) is estimated to be from 0.40 at.% to 2.95 at.% for different doping levels. A reduction in T{sub c} from 38.43 to 34.93 K and in lattice parameter a from 3.084(3) A to 3.075(6) A is observed for the 10 wt% C{sub 6}H{sub 10}O{sub 4} doped sample in comparison to pristine MgB{sub 2}. This is an indication of C substitution at boron sites, with the C coming from the decomposition of C{sub 6}H{sub 10}O{sub 4} at the time of reaction. Interestingly the doped samples have resulted in significant enhancement of J{sub c} and H{sub irr}. All the doped samples exhibit the J{sub c} value of the order of 10{sup 4} A cm{sup -2} at 5 K and 8 T, which is higher by an order of magnitude as compared to the undoped sample. This result indicates that C{sub 6}H{sub 10}O{sub 4} is a promising material for MgB{sub 2} for obtaining the excellent J{sub c} values under higher magnetic fields.

  4. EPR investigations of silicon carbide nanoparticles functionalized by acid doped polyaniline

    Science.gov (United States)

    Karray, Fekri; Kassiba, Abdelhadi

    2012-06-01

    Nanocomposites (SiC-PANI) based on silicon carbide nanoparticles (SiC) encapsulated in conducting polyaniline (PANI) are synthesized by direct polymerization of PANI on the nanoparticle surfaces. The conductivity of PANI and the nanocomposites was modulated by several doping levels of camphor sulfonic acid (CSA). Electron paramagnetic resonance (EPR) investigations were carried out on representative SiC-PANI samples over the temperature range [100-300 K]. The features of the EPR spectra were analyzed taking into account the paramagnetic species such as polarons with spin S=1/2 involved in two main environments realized in the composites as well as their thermal activation. A critical temperature range 200-225 K was revealed through crossover changes in the thermal behavior of the EPR spectral parameters. Insights on the electronic transport properties and their thermal evolutions were inferred from polarons species probed by EPR and the electrical conductivity in doped nanocomposites.

  5. Copper- or manganese-doped ZnS quantum dots as fluorescent probes for detecting folic acid in aqueous media

    Energy Technology Data Exchange (ETDEWEB)

    Geszke-Moritz, Malgorzata [Laboratoire Reactions et Genie des Procedes (LRGP), Nancy-University, CNRS, 1 rue Grandville, 54001 Nancy Cedex (France); Department of Pharmaceutical Technology, Poznan University of Medical Sciences, Grunwaldzka 6, 60-780 Poznan (Poland); Clavier, Gilles [PPSM, ENS Cachan, CNRS, UniverSud, 61 avenue President Wilson, 94230 Cachan (France); Lulek, Janina [Department of Pharmaceutical Technology, Poznan University of Medical Sciences, Grunwaldzka 6, 60-780 Poznan (Poland); Schneider, Raphaeel, E-mail: raphael.schneider@ensic.inpl-nancy.fr [Laboratoire Reactions et Genie des Procedes (LRGP), Nancy-University, CNRS, 1 rue Grandville, 54001 Nancy Cedex (France)

    2012-04-15

    3-Mercaptopropionic acid-capped core/shell ZnS:Cu/ZnS and ZnS:Mn/ZnS doped quantum dots (QDs) prepared through hydrothermal methods exhibit high photoluminescence intensity as well as good photostability. These water-dispersible nanoparticles exhibit high fluorescence sensitivity to folic acid due to the high affinity of the carboxylate groups and nitrogen atoms of folic acid towards the Zn surface atoms of the doped dots. Quenching of the fluorescence intensity of the QDs allows the detection of folic acid concentrations as low as 11 {mu}M, thus affording a very sensitive system for the sensing of this biologically active molecule in aqueous solution. The possible quenching mechanism is discussed. - Graphical abstract: A sensitive method for the detection of folic acid based on the fluorescence quenching of Mn- or Cu-doped ZnS quantum dots was developed. Highlights: Black-Right-Pointing-Pointer Quenching of the fluorescence intensity of doped ZnS QDs in the presence of folic acid. Black-Right-Pointing-Pointer New fluorescent sensors for folic acid. Black-Right-Pointing-Pointer Detection of folic acid concentrations as low as 11 {mu}M in aqueous solution. Black-Right-Pointing-Pointer The Perrin model and fluorescence lifetimes of ZnS:Mn QDs demonstrate a static quenching mechanism. Black-Right-Pointing-Pointer Quenching efficiency of ZnS:Cu QDs correlates with the Stern-Volmer model.

  6. Activation procedures characterization of MEA based on phosphoric acid doped PBI membranes

    Energy Technology Data Exchange (ETDEWEB)

    Boaventura, M.; Mendes, A. [Laboratorio de Engenharia de Processos, Ambiente e Energia (LEPAE), Faculdade de Engenharia da Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal)

    2010-10-15

    This work aims at better understanding the activation process of phosphoric acid doped PBI-based MEA. The phenomena involved in the activation of Celtec {sup registered} - P1000 MEA were studied based on polarization curves, AC impedance spectroscopy combined with equivalent circuit modelling and cyclic voltammetry analysis. It was concluded that galvanostatic activation procedure enhanced Celtec {sup registered} - P1000 MEA performance by increasing the catalyst activity and by decreasing the ohmic resistance. Also, galvanostatic and potential cycling procedures were applied to an in-house prepared MEA; for the same activation time, the galvanostatic allowed a deeper activation of the in-house prepared MEA than the potential cycling activation method. It is accepted that the humidification of the reactants is not necessary for high temperature PEMFC based on phosphoric acid doped PBI membrane, since water production at the cathode should be enough to ensure high performance of the fuel cell. In this work it is described the behavior of a PEMFC based on an in-house prepared MEA, after activation at different temperatures and relative humidities. It is shown that water has an enhanced effect on ohmic resistance during the PEMFC operation but can also have a detrimental effect on the cathode resistance due to migration of phosphoric acid outside MEA. (author)

  7. Corrosion Protection Properties and Mechanism of Epoxy/Acetic Acid-Doped Polyaniline Coating on Magnesium Alloy.

    Science.gov (United States)

    Jin, Tao; Wang, Yanmin; Yin, Hong; Hao, Xiaojuan

    2018-07-01

    Poly(amidoamine)(PAMAM)/epoxy/acetic acid-doped polyaniline (PAni) coatings were successfully prepared and coated on magnesium alloy substrates. X-ray diffraction pattern, Fourier transform infrared spectroscopy, scanning electron microscopy technique were used to characterize the composition and morphology of acetic acid-doped PAni and composite coatings. The effect of the usage amount of doped PAni on the corrosion protection performance was evaluated with electrochemical measurement in 3.5 wt.% NaCl solutions. Tafel and electrochemical impedance spectroscopy analysis revealed that the addition of 1.0 wt.% doped PAni provided the superior corrosion protection properties. The corrosion protection mechanism was investigated by using electron probe microanalysis test and theoretical physical model. The doped PAni could obviously shrink the pits and made epoxy resin matrix denser by cross-linking and hydrogen bonding. The composite coatings exhibited better corrosion protection properties compared to pure epoxy coating. The in situ generated corrosion products provided anodic corrosion inhibition due to the easier penetration of acetate ions, and better physical barrier mechanism was promoted by the addition of doped PAni.

  8. Photocatalytic decomposition of perfluorooctanoic acid by iron and niobium co-doped titanium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Renan Estrellan, Carl, E-mail: estrellan.c.ac@m.titech.ac.jp [Department of International Development Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan); Salim, Chris; Hinode, Hirofumi [Department of International Development Engineering, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550 (Japan)

    2010-07-15

    The photocatalytic decomposition of perfluorooctanoic acid (PFOA) in aqueous solution using Fe and Nb co-doped TiO{sub 2} (Fe:Nb-TiO{sub 2}) prepared by sol-gel method was investigated. The photocatalytic activity of Fe:Nb-TiO{sub 2} towards PFOA degradation was compared to that of pure TiO{sub 2} synthesized using the same method, and that of the commercially available TiO{sub 2} photocatalyst, Aeroxide TiO{sub 2} P25 (AO-TiO{sub 2} P25). The photocatalysts were characterized by XRD, DRS, BET-N{sub 2} adsorption isotherm, and SEM-EDX techniques and the data were correlated to the photocatalytic activity. Fe:Nb-TiO{sub 2} showed the highest activity compared to the undoped TiO{sub 2} and the commercially available TiO{sub 2}. Such activity was attributable to the effects of co-doping both on the physico-chemical properties and surface interfacial charge transfer mechanisms. Perfluorocarboxylic acids (PFCAs) with shorter carbon chain length and fluoride ions were identified as photocatalytic reaction intermediates and products.

  9. Phytic acid doped polyaniline containing epoxy coatings for corrosion protection of Q235 carbon steel

    Science.gov (United States)

    Hao, Yongsheng; Sani, Luqman Abdullahi; Ge, Tiejun; Fang, Qinghong

    2017-10-01

    Corrosion protection of epoxy coatings contained with phytic acid-doped polyaniline (PANI-PA) for Q235 carbon steel was studied in this work. Synthesized PANI-PA particles were characterized by XPS, TGA, and FTIR, respectively. The coating performance was investigated by OCP, EIS, and SVET, respectively. The experimental results show that the concentration of PANI-PA has a significant influence to the barrier effect of the epoxy coating. Epoxy coating loaded with 2 wt.% PANI-PA has the best protection ability and self-healing function to a certain degree. The self-healing function of PANI-PA is attributed to the synergistic effect of the passivation of PANI and the chelation of the dedoped phytic acid ions with iron ions. Therefore, PANI-PA can be used as an effective anticorrosion pigment in future.

  10. Properties of the Surface Layer of Thin Films of Polyaniline Doped With Phosphoric Acid

    Directory of Open Access Journals (Sweden)

    Almedina Modrić-Šahbazović

    2016-08-01

    Full Text Available This study deals with estimation of the surface free energy of thin films of polyaniline doped with phosphoric acid, by measuring contact angles. Synthesis of polyaniline (PANI with phosphoric acid (PA was performed at room temperature of 20°C, and at 0°C. Thin films were obtained by means of a spin coater, applying the synthetized mixture on a glass substrate. By measuring the contact angle, first between ethylene glycol and a film and then between distilled water and a film, we thus calculated the polar, dispersion and total surface free energy. It was proved and demonstrated that the surface free energy depends on the temperature at which the solution (from which the thin films are obtained later was synthesized.

  11. A nitrogen-doped graphene/gold nanoparticle/formate dehydrogenase bioanode for high power output membrane-less formic acid/O2 biofuel cells.

    Science.gov (United States)

    Gai, Panpan; Ji, Yusheng; Chen, Yun; Zhu, Cheng; Zhang, Jianrong; Zhu, Jun-Jie

    2015-03-21

    A high power output, membrane-less formic acid/O2 enzymatic biofuel cell was fabricated, in which nitrogen-doped graphene was proven to be effective for recycling the NAD(+)/NADH cofactor at a nitrogen-doped graphene/gold nanoparticle/formate dehydrogenase bioanode in the catalytic oxidation of formic acid.

  12. N, S co-doped carbon dots with orange luminescence synthesized through polymerization and carbonization reaction of amino acids

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Ya-Wen [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Ma, De-Kun, E-mail: dkma@wzu.edu.cn [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou, Zhejiang 325027 (China); Wang, Wei; Chen, Jing-Jing; Zhou, Lin; Zheng, Yi-Zhou [Department of Hematology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027 (China); Yu, Kang, E-mail: yukang62@126.com [Department of Hematology, The First Affiliated Hospital of Wenzhou Medical University, Wenzhou, Zhejiang 325027 (China); Huang, Shao-Ming, E-mail: smhuang@wzu.edu.cn [Nanomaterials and Chemistry Key Laboratory, Wenzhou University, Wenzhou, Zhejiang 325027 (China)

    2015-07-01

    Graphical abstract: N, S co-doped CDs with orange luminescence were synthesized through one-pot polymerization and carbonization reactions under hydrothermal conditions, using two different amino acids as raw materials. - Highlights: • N, S co-doped CDs were synthesized by one-pot carbonization reactions, using two different amino acids as raw materials. • The as-obtained N, S co-doped CDs showed unique orange fluorescence under excitation at room temperature. • The products could be applied in the imaging of peritoneal macrophages of mice without any functionalization. - Abstract: For practical application, it is highly desirable to obtain carbon dots (CDs) through environmentally benign synthetic route, using green raw materials. On the other hand, at present, most of CDs reported in the literature showed blue, green and yellow emission. Therefore it is still necessary to develop new strategy to obtain CDs with longer wavelength emission in order to expand their application range. Toward this end, in this study, N, S co-doped CDs were synthesized through one-pot condensation polymerization and carbonization reactions under hydrothermal conditions, using two different amino acids as raw materials. Taking the reaction of L-serine with L-cystine as an example, the as-obtained products were characterized by various techniques such as transmission electron microscopy, elemental analysis, Fourier-transform infrared spectrum, X-ray photoelectron spectra, and so on. Interestingly, N, S co-doped CDs displayed unique orange emission at room temperature. The possible photoluminescence mechanism of N, S co-doped CDs was proposed. Furthermore, the as-synthesized N, S co-doped CDs were directly applied in the imaging of peritoneal macrophages of mice.

  13. Polybenzimidazole membranes for zero gap alkaline electrolysis cells

    DEFF Research Database (Denmark)

    Kraglund, Mikkel Rykær; Aili, David; Christensen, Erik

    Membranes of m-PBI doped in KOH (aq), 15-35 wt%, show high ionic conductivity in the temperature range 20-80 ºC. In electrolysis cells with nickel foam electrodes m-PBI membranesprovide low internal resistance. With a 60 µm membraneat 80ºC in 20 wt% KOH,1000 mA/cm2 is achieved at 2.25.......Membranes of m-PBI doped in KOH (aq), 15-35 wt%, show high ionic conductivity in the temperature range 20-80 ºC. In electrolysis cells with nickel foam electrodes m-PBI membranesprovide low internal resistance. With a 60 µm membraneat 80ºC in 20 wt% KOH,1000 mA/cm2 is achieved at 2.25....

  14. Performance Degradation Tests of Phosphoric Acid Doped PBI Membrane Based High Temperature PEM Fuel Cells

    DEFF Research Database (Denmark)

    Zhou, Fan; Araya, Samuel Simon; Grigoras, Ionela

    2014-01-01

    Degradation tests of two phosphoric acid (PA) doped PBI membrane based HT-PEM fuel cells were reported in this paper to investigate the effects of start/stop and the presence of methanol in the fuel to the performance degradation. Continuous tests with H2 and simulated reformate which was composed...... of H2, water steam and methanol as the fuel were performed on both single cells. 12-h-startup/12-h-shutdown dynamic tests were performed on the first single cell with pure dry H2 as the fuel and on the second single cell with simulated reformate as the fuel. Along with the tests electrochemical...... techniques such as polarization curves and electrochemical impedance spectroscopy (EIS) were employed to study the degradation mechanisms of the fuel cells. Both single cells showed an increase in the performance in the H2 continuous tests, because of a decrease in the ORR kinetic resistance probably due...

  15. EPR, optical and superposition model study of Mn2+ doped L+ glutamic acid

    Science.gov (United States)

    Kripal, Ram; Singh, Manju

    2015-12-01

    Electron paramagnetic resonance (EPR) study of Mn2+ doped L+ glutamic acid single crystal is done at room temperature. Four interstitial sites are observed and the spin Hamiltonian parameters are calculated with the help of large number of resonant lines for various angular positions of external magnetic field. The optical absorption study is also done at room temperature. The energy values for different orbital levels are calculated, and observed bands are assigned as transitions from 6A1g(s) ground state to various excited states. With the help of these assigned bands, Racah inter-electronic repulsion parameters B = 869 cm-1, C = 2080 cm-1 and cubic crystal field splitting parameter Dq = 730 cm-1 are calculated. Zero field splitting (ZFS) parameters D and E are calculated by the perturbation formulae and crystal field parameters obtained using superposition model. The calculated values of ZFS parameters are in good agreement with the experimental values obtained by EPR.

  16. Phosphoric acid doped imidazolium polysulfone membranes for high temperature proton exchange membrane fuel cells

    DEFF Research Database (Denmark)

    Yang, Jingshuai; Li, Qingfeng; Jensen, Jens Oluf

    2012-01-01

    A novel acid–base polymer membrane is prepared by doping of imidazolium polysulfone with phosphoric acid for high temperature proton exchange membrane fuel cells. Polysulfone is first chloromethylated, followed by functionalization of the chloromethylated polysulfone with alkyl imidazoles i...... group is achieved in 85wt% H3PO4 at room temperature. The membranes exhibit a proton conductivity of 0.015–0.022Scm−1 at 130–150°C under 15mol% water vapor in air, and a tensile strength of 5–6MPa at 130°C under ambient humidity. Fuel cell tests show an open circuit voltage as high as 0.96V and a peak...

  17. Study of spatial rings in TPPOH4 doped in boric acid glass

    Science.gov (United States)

    Rao Allam, Srinivasa; Dar, Mudasir H.; Venkatramaiah, N.; Venkatesan, R.; Sharan, Alok

    2015-02-01

    Single beam optical nonlinearity is studied in TPPOH4 doped in boric acid sandwiched films between two microscope glass slides at three different molar concentrations (4×10-4M, 1×10-4M, 5×10-5M). It shows absorption peak at 700nm with bandwidth of 70nm. We have used diode laser output at 671nm to probe resonant optical nonlinearities. We have observed interesting phenomena of formation of spatial concentric rings centered on the z-axis of the sample. To our knowledge this is first such observation of spatial rings in these systems. We have carried out studies to separate the contribution to the ring formation due to absorptive/refractive optical nonlinearity and the thermal nonlinearity.

  18. Ammonia Gas Sensing Behavior of Tanninsulfonic Acid Doped Polyaniline-TiO2 Composite

    Directory of Open Access Journals (Sweden)

    Venu Gopal Bairi

    2015-10-01

    Full Text Available A highly active tannin doped polyaniline-TiO2 composite ammonia gas sensor was developed and the mechanism behind the gas sensing activity was reported for the first time. A tanninsulfonic acid doped polyaniline (TANIPANI-titanium dioxide nanocomposite was synthesized by an in situ polymerization of aniline in the presence of tanninsulfonic acid and titanium dioxide nanoparticles. X-ray diffraction and thermogravimetric analysis were utilized to determine the incorporation of TiO2 in TANIPANI matrix. UV-Visible and infrared spectroscopy studies provided information about the electronic interactions among tannin, polyaniline, and TiO2. Scanning electron microscopy (SEM along with energy dispersive X-ray spectroscopy (EDS and atomic force microscopy (AFM surface analysis techniques were used to investigate the metal oxide dispersions inside polyaniline matrix. Gas sensors were prepared by spin coating solutions of TANIPANI-TiO2 and TANIPANI composites onto glass slides. Sensors were tested at three different concentrations (20 ppm, 40 ppm, and 60 ppm of ammonia gas at ambient temperature conditions by measuring the changes in surface resistivity of the films with respect to time. Ammonia gas sensing plots are presented showing the response values, response times and recovery times. The TANIPANI-TiO2 composite exhibited better response and shorter recovery times when compared to TANIPANI control and other polyaniline composites that have been reported in the literature. For the first time a proposed mechanism of gas sensing basing on the polaron band localization and its effects on the gas sensing behavior of polyaniline are reported.

  19. N-doped carbon nanomaterials are durable catalysts for oxygen reduction reaction in acidic fuel cells

    Science.gov (United States)

    Shui, Jianglan; Wang, Min; Du, Feng; Dai, Liming

    2015-01-01

    The availability of low-cost, efficient, and durable catalysts for oxygen reduction reaction (ORR) is a prerequisite for commercialization of the fuel cell technology. Along with intensive research efforts of more than half a century in developing nonprecious metal catalysts (NPMCs) to replace the expensive and scarce platinum-based catalysts, a new class of carbon-based, low-cost, metal-free ORR catalysts was demonstrated to show superior ORR performance to commercial platinum catalysts, particularly in alkaline electrolytes. However, their large-scale practical application in more popular acidic polymer electrolyte membrane (PEM) fuel cells remained elusive because they are often found to be less effective in acidic electrolytes, and no attempt has been made for a single PEM cell test. We demonstrated that rationally designed, metal-free, nitrogen-doped carbon nanotubes and their graphene composites exhibited significantly better long-term operational stabilities and comparable gravimetric power densities with respect to the best NPMC in acidic PEM cells. This work represents a major breakthrough in removing the bottlenecks to translate low-cost, metal-free, carbon-based ORR catalysts to commercial reality, and opens avenues for clean energy generation from affordable and durable fuel cells. PMID:26601132

  20. Dual responsive dysprosium-doped hydroxyapatite particles and toxicity reduction after functionalization with folic and glucuronic acids

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez Lafarga, Ana Karen; Pacheco Moisés, Fermín P. [Departamento de Química, Universidad de Guadalajara, Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico); Gurinov, Andrey [Research Resources Center for Magnetic Resonance, Saint Petersburg State University, Universitetskij pr. 26, 198504 St. Petersburg (Russian Federation); Ortiz, Genaro Gabriel [Laboratorio Desarrollo-Envejecimiento, Enfermedades Neurodegenerativas, Centro de Investigación Biomédica de Occidente (CIBO), Instituto Mexicano de Seguro Social (IMSS), Guadalajara, Jalisco (Mexico); Carbajal Arízaga, Gregorio Guadalupe, E-mail: gregoriocarbajal@yahoo.com.mx [Departamento de Química, Universidad de Guadalajara, Marcelino García Barragán 1421, C.P. 44430, Guadalajara, Jalisco (Mexico)

    2015-03-01

    The development of probes for biomedical applications demands materials with low toxicity levels besides fluorescence or magnetic properties to be detected by confocal microscopes or MRI resonators. Several drug delivery systems or other biomedical materials prepared with hydroxyapatite have been proposed, however, toxicity effects might arise when the size of particles is nanometric. In this study, hydroxyapatite functionalized with glucuronic or folic acids presented lower oxidative stress, measured from lipoperoxides and nitric oxide indicators in rats than pure hydroxyapatite. In separated experiments, hydroxyapatite was doped with dysprosium cations by coprecipitation producing a single crystal phase with fluorescent properties easily visualized by confocal microscopy when excited at 488 nm. These particles also presented the ability to modify the proton relaxation time in T1 maps collected by magnetic resonance imaging. These modified hydroxyapatite nanoparticles could be candidates to design bimodal probes with low toxicity. - Highlights: • Hydroxyapatite functionalized with glucuronic acid reduced oxidative stress in rats. • Functionalization with folic acid reduced oxidative stress in rats. • Dysprosium doping does not affect the crystalline structure of hydroxyapatite. • Dysprosium doped particles are visible in fluorescent microscope. • Dysprosium doped particles act as MRI contrast agents.

  1. Effect of sorbic acid doping on flux pinning in bulk MgB 2 with the percolation model

    Science.gov (United States)

    Yang, Y.; Cheng, C. H.; Wang, L.; Sun, H. H.; Zhao, Y.

    2010-11-01

    In this paper, we study the doping effect of sorbic acid (C6H8O2), from 0 to 20 wt.% of the total MgB2, on critical temperature (Tc), critical current density (Jc), irreversibility field (Hirr) and crystalline structure. The XRD patterns of samples show a slightly decrease in a-axis lattice parameter for doped samples, due to the partial substitution of carbon at boron site. On the other hand, we investigate the influence of doping on the behavior of flux pinning and Jc(B) in the framework of percolation theory and it is found that the Jc(B) behavior could be well fitted in high field region. The two key parameters, anisotropy and percolation threshold, play very important roles. It is believed that the enhancement of Jc is due to the reduction of anisotropy in high field region.

  2. Enhancement in the critical current density of C-doped MgB2 wire using a polyacrylic acid dopant.

    Science.gov (United States)

    Lee, Seung Muk; Hwang, Soo Min; Lee, Chang Min; Kim, Won; Joo, Jinho; Lim, Jun Hyung; Kim, Chan-Joong; Hong, Gye-Won

    2012-02-01

    C-doped MgB2 wires were fabricated from a polyacrylic acid (PAA) using a conventional in-situ PIT technique. The effects of the PAA content on the lattice parameter, microstructure, critical temperature (Tc) and critical current density (Jc) were examined. With increasing PAA content, the amount of MgO in the sample increased but the crystallinity, a-axis lattice parameter, and Tc of MgB2 wires decreased, indicating that the C that decomposed from PAA during heat treatment had substituted for B. All doped samples exhibited a higher Jc than the undoped sample at high magnetic field, and the Jc(B) property improved with increasing PAA content: for the 7 wt% doped sample, the Jc was approximately 3-times higher than that of the pristine sample (1.28 kA/cm2 vs. 3.43 kA/cm2) at 5 K and 6.6 T. The improved Jc(B) of the doped sample was attributed to the decreased grain size, enlarged lattice distortion and increased C doping level.

  3. Fabrication of Polybenzimidazole/Palladium Nanoparticles Hollow Fiber Membranes for Hydrogen Purification

    KAUST Repository

    Villalobos, Luis Francisco

    2017-09-13

    A novel scheme to fabricate polybenzimidazole (PBI) hollow fiber membranes with a thin skin loaded with fully dispersed palladium nanoparticles is proposed for the first time. Palladium is added to the membrane during the spinning process in the form of ions that coordinate to the imidazole groups of the polymer. This is attractive for membrane production because agglomeration of nanoparticles is minimized and the high-cost metal is incorporated in only the selective layer—where it is required. Pd-containing membranes achieve three orders of magnitude higher H2 permeances and a twofold improvement in H2/CO2 selectivity compared to pure PBI hollow fiber membranes.

  4. Facile synthesis and enhanced visible light photocatalytic activity of N and Zr co-doped TiO2 nanostructures from nanotubular titanic acid precursors

    Science.gov (United States)

    Zhang, Min; Yu, Xinluan; Lu, Dandan; Yang, Jianjun

    2013-12-01

    Zr/N co-doped TiO2 nanostructures were successfully synthesized using nanotubular titanic acid (NTA) as precursors by a facile wet chemical route and subsequent calcination. These Zr/N-doped TiO2 nanostructures made by NTA precursors show significantly enhanced visible light absorption and much higher photocatalytic performance than the Zr/N-doped P25 TiO2 nanoparticles. Impacts of Zr/N co-doping on the morphologies, optical properties, and photocatalytic activities of the NTA precursor-based TiO2 were thoroughly investigated. The origin of the enhanced visible light photocatalytic activity is discussed in detail.

  5. Gas transport properties of polybenzimidazole and poly(phenylene oxide) mixed matrix membranes incorporated with PDA-functionalised titanate nanotubes

    Czech Academy of Sciences Publication Activity Database

    Giel, Verena; Perchacz, Magdalena; Kredatusová, Jana; Pientka, Zbyněk

    2017-01-01

    Roč. 12, č. 1 (2017), s. 1-15, č. článku 3. ISSN 1931-7573 R&D Projects: GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : polybenzimidazole * poly(phenylene oxide) * titanate nanotubes Subject RIV: CD - Macromolecular Chemistry OBOR OECD: Polymer science

  6. Simultaneous Chronoamperometric Sensing of Ascorbic Acid and Acetaminophen at a Boron-Doped Diamond Electrode

    Directory of Open Access Journals (Sweden)

    Ciprian Radovan

    2008-06-01

    Full Text Available Cyclic voltammetry (CV and chronoamperometry (CA have been used to sense and determine simultaneously L-ascorbic acid (AA and acetaminophen (AC at a boron-doped diamond electrode (BDDE in a Britton-Robinson buffer solution. The calibration plots of anodic current peak versus concentration obtained from CV and CA data for both investigated compounds in single and di-component solutions over the concentration range 0.01 mM – 0.1 mM proved to be linear, with very good correlation parameters. Sensitivity values and RSD of 2-3% were obtained for various situations, involving both individual and simultaneous presence of AA and AC. The chronoamperometric technique associated with standard addition in sequential one step and/or two successive and continuous chronoamperograms at two characteristic potential levels represented a feasible option for the simultaneous determination of AA and AC in real sample systems such as pharmaceutical formulations. The average values indicated by the supplier were confirmed to a very close approximation from chronoamperomgrams by using several additions with the application of suitable current correction factors.

  7. Synthesis and Bactericidal Properties of Hyaluronic Acid Doped with Metal Nanoparticles

    Directory of Open Access Journals (Sweden)

    Galo Cárdenas-Triviño

    2017-01-01

    Full Text Available A study on the nanoparticles size and the antibacterial properties of hyaluronic acid (HA doped with nanoparticles is reported. Nanoparticles from gold, silver, copper, and silver palladium with HA support were performed. The solvated metal atom dispersion (SMAD method with 2-propanol and HA was used. High-resolution transmission electron microscopy (HRTEM, infrared spectroscopy (FT-IR, and thermogravimetric analysis (TGA were conducted. The average sizes of nanoclusters were as follows: HA-Au = 17.88 nm; HA-Ag = 50.41 nm; HA-Cu = 13.33 nm; and HA-AgPd = 33.22 nm. The antibacterial activity of solutions and films containing nanoparticles against American Type Culture Collection (ATCC bacterial strains Escherichia coli (EC, Staphylococcus aureus (SA, Staphylococcus epidermidis (SE, and Pseudomonas aeruginosa (PA was determined. Inhibition was observed for HA-Ag, HA-Cu, and HA-AgPd. Toxicological tests were performed in rats that were injected intraperitoneally with two concentrations of gold, copper, silver, and silver-palladium nanoparticles. No alterations in hepatic parameters, including ALT (alanine aminotransferase, GGT (gamma-glutamyl transpeptidase bilirubin, and albumin, were observed after 14 days. These films could be used as promoters of skin recovery and Grades I and II cutaneous burns and as scaffolds.

  8. Nitrogen doped graphene quantum dots based long-persistent chemiluminescence system for ascorbic acid imaging.

    Science.gov (United States)

    Chen, Hongjun; Wang, Qin; Shen, Qinpeng; Liu, Xin; Li, Wang; Nie, Zhou; Yao, Shouzhuo

    2017-05-15

    High photo-intensity and sluggish flight attenuation are important to highly sensitive chemluminescence imaging. Herein, we present a copper ion catalyzed long-persistent chemiluminescent imaging system of nitrogen-doped graphene quantum dots (NGQDs) for ascorbic acid detection in fruit. NGQDs as luminescent probe are fabricated, emitting out chemluminescence with the direct oxidation by H 2 O 2 . In addition, Cu 2+ ion enlarges over two order magnitudes of NGQDs CL intensity (214 times) due to its catalyzed Fenton-like reaction for H 2 O 2 decomposition, and displaying unique specificity against other metal ions. As a result, the twinkling luminescence of NGQDs is boosted and changes to hold persistent with small decay in the presence of copper ion exhibiting potential for CL imaging. As an imaging model, a visual sensor based on Cu 2+ /NGQDs/H 2 O 2 is developed for AA quantitative monitoring with a limit of detection (LOD) of 0.5μM (S/N=3) and applied in real AA detection in fruit. The CL imaging method demonstrated with high stability and proper sensitivity would provide a convenient and visual tool for AA determination, displaying promising candidates for imaging sensing. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Photophysical characterization of cumarin-doped poly (lactic acid) microparticles and visualization of the biodistribution

    Energy Technology Data Exchange (ETDEWEB)

    Abe, Shigeaki, E-mail: sabe@den.hokudai.ac.j [Department of Biomedical Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Sapporo 060-8586 (Japan); Kiba, Takayuki; Hosokawa, Kiyotada; Nitobe, Satoru; Hirota, Takashi; Kobayashi, Hirohisa [Division of Biotechnology and Macromolecular Chemistry, Graduate School of Hokkaido University, Sapporo 060-8628 (Japan); Akasaka, Tsukasa; Uo, Motohiro; Kuboki, Yoshinori [Department of Biomedical Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Sapporo 060-8586 (Japan); Sato, Shin-Ichiro [Division of Biotechnology and Macromolecular Chemistry, Graduate School of Hokkaido University, Sapporo 060-8628 (Japan); Watari, Fumio [Department of Biomedical Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, Kita 13, Nishi 7, Sapporo 060-8586 (Japan); Rosca, Iosif D. [Faculty of Engineering and Computer Science, Concordia University, 1455 de Maisonneuve Blvd. W, Montreal, QC H3G 1M8 (Canada)

    2010-08-15

    We prepared fluorescent coumarin dye-doped poly (acrylic acid) microparticles, which are well known as a biodegradable polyester, and the photophysical properties were characterized by scanning electron microscope, atomic force microscope and spectroscopic investigation. Spherical particles with diameters ranging from 0.5 to a few {mu}m were obtained. Based on spectroscopic investigation, the internal environment was close to that of a polar solvent such as methanol, and the dyes were dispersed without aggregation inside the particles. The obtained particles were administered to a mouse through the tail vein, and the biodistribution was then observed after some organs were excited at 1-day and 1-week post-injection. The particles were accumulated in the organs, especially in the lung and spleen. After injection, the particles were trapped temporally in the lung, and then seemed to be transported to other organs by blood circulation. This tendency is similar to the biodistribution of TiO{sub 2} microparticles that we have reported previously.

  10. Effect of acid leaching conditions on impurity removal from silicon doped by magnesium

    Directory of Open Access Journals (Sweden)

    Stine Espelien

    2017-07-01

    Full Text Available The effect of magnesium addition into a commercial silicon and its leaching refining behavior is studied for producing solar grade silicon feedstock. Two different levels of Mg is added into a commercial silicon and the leaching of the produced alloys by 10% HCl solution at 60 ℃ for different durations is performed. It is shown that the microstructure of the alloy and in particular the distribution of eutectic phases is dependent on the amount of the added Mg. Moreover, the metallic impurities in silicon such as Fe, Al, Ca and Ti are mainly forming silicide particles with different compositions. These silicides are physically more detached from the primary silicon grains and their removal through chemical and physical separation in leaching is better for higher Mg additions. It is observed that the leaching is more effective for the purification of smaller silicon particles produced from each Mg-doped silicon alloy. It is shown that acid leaching by the applied method is effective to reach more than 70% of phosphorous removal. It is also shown that the purity of silicon is dependent on the total Mg removal and effectiveness of leaching on removing the Mg2Si phase.

  11. Enhanced Fischer-Tropsch synthesis performance of iron-based catalysts supported on nitric acid treated N-doped CNTs

    Science.gov (United States)

    Li, Zhenhua; Liu, Renjie; Xu, Yan; Ma, Xinbin

    2015-08-01

    Iron-based catalysts supported on N-doped CNTs (NCNTs) treated by various concentrations of nitric acid for Fischer-Tropsch synthesis (FTS) were investigated. An improved catalytic performance for the iron catalyst supported on acid treated NCNTs was obtained and the suitable nitric acid concentration was 10 M. The physiochemical properties of the NCNTs and the corresponding catalysts were characterized by BET, TEM, XRD, XPS, TGA and H2-TPR. The acid treatment removed the impurity and amorphous carbon, damaged the bamboo-like structure and increased the number of oxygen-containing functional groups and graphitization degree on the NCNTs. The more iron particles located inside the channels of NCNTs, the better catalytic FTS performance due to high dispersion and reducibility.

  12. Lanthanum-doped mesostructured strontium titanates synthesized via sol–gel combustion route using citric acid as complexing agent

    Energy Technology Data Exchange (ETDEWEB)

    Sukpanish, Polthep [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Lertpanyapornchai, Boontawee [Program in Petrochemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Yokoi, Toshiyuki [Division of Catalytic Chemistry, Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Ngamcharussrivichai, Chawalit, E-mail: Chawalit.Ng@chula.ac.th [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand)

    2016-09-15

    In the present work, a series of lanthanum-doped mesostructured strontium titanate (LMST) materials with different La/Sr ratios were synthesized via a sol–gel combustion method in the presence of citric acid as a complexing agent and Pluronic P123 as a templating agent. The effects of the amount of doped La and calcination temperature on the physicochemical properties of the LMSTs were examined using various techniques. Powder X-ray diffraction confirmed the substitution of La{sup 3+} into the SrTiO{sub 3} lattice, generating cubic perovskite La{sub x}Sr{sub 1−x}TiO{sub 3}, for the LMST materials calcined at 600 °C. The purity and crystallinity of the desired perovskite phase were enhanced by citric acid addition. The solubility limit of La{sup 3+} substitution at an La/Sr ratio of 0.43 was determined by structural and morphological studies. Increasing the La doping amount decreased the crystallinity and compositional homogeneity, because an La-rich amorphous phase segregated on the surface, but improved the mesoporosity. N{sub 2} physisorption measurements indicated that the LMSTs had a bimodal pore size distribution, of which the larger one was characterized by the crystallite size of mixed oxides, and the specific surface area of 24.9–37.3 m{sup 2} g{sup −1}. The formation of mesopores in the LMST materials synthesized via sol–gel combustion was explained based on a combination of soft- and hard-templating chemistries. - Highlights: • La-doped mesoporous SrTiO{sub 3} (LMST) was prepared first time via sol-gel combustion. • Pluronic P123 triblock copolymer was used as a cheap templating agent. • Citric acid as a complexing agent enhanced the purity and crystallinity of SrTiO{sub 3}. • The textural properties of LMST were improved by increasing the La doping amount. • Mesopore formation was explained by a combined soft- and hard-templating route.

  13. Study of pure and L-tartaric acid doped ammonium dihydrogen phosphate single crystals: A novel nonlinear optical non-centrosymmetric crystal

    Energy Technology Data Exchange (ETDEWEB)

    Hasmuddin, Mohd, E-mail: mhasmu@gmail.com [Crystal Growth Laboratory, Dept. of Physics, Jamia Millia Islamia, New Delhi 110 025 (India); Singh, Preeti [Crystal Growth Laboratory, Dept. of Physics, Jamia Millia Islamia, New Delhi 110 025 (India); Shkir, Mohd [Crystal Growth Laboratory, Dept. of Physics, Jamia Millia Islamia, New Delhi 110 025 (India); Department of Physics, School of Science, King Khalid University, P.O. Box. 9004, Abha 61413 (Saudi Arabia); Abdullah, M.M. [Crystal Growth Laboratory, Dept. of Physics, Jamia Millia Islamia, New Delhi 110 025 (India); Promising Centre for Sensors and Electronic Devices (PCSED), Department of Physics, College of Science and Arts, Najran University, P.O. Box 1988, Najran 11001 (Saudi Arabia); Vijayan, N. [CSIR – National Physical Laboratory, Dr. K. S. Krishnan Road, New Delhi 110 012 (India); Ganesh, V. [Department of Physics, Kakatiya University, Warangal, Andhra Pradesh 506009 (India); Wahab, M.A., E-mail: mwahab@jmi.ac.in [Crystal Growth Laboratory, Dept. of Physics, Jamia Millia Islamia, New Delhi 110 025 (India)

    2014-04-01

    Single crystals of pure and L-tartaric acid (LTA) C{sub 4}H{sub 6}O{sub 6} doped ammonium dihydrogen phosphate (ADP) (NH{sub 4}) H{sub 2}PO{sub 4} were grown by slow evaporation solution technique (SEST) at ambient conditions. Powder X-ray diffraction (PXRD) analysis was carried out to confirm the crystal structure and no additional phase was observed due to doping except a systematic variation in peak intensities. Fourier transform infrared spectral analysis was done to examine the presence of various functional groups in the grown crystals. UV–VIS–NIR spectroscopic analysis was carried out to see the change in optical transparency of pure ADP and crystals due to LTA with different doping concentrations. Second harmonic generation (SHG) efficiency measurement was done to examine the enhancement in the nonlinear optical characteristics of the grown crystals. The effect of LTA dopant on crystal morphology, thermal and mechanical properties of ADP have also been presented in this paper. The above studies reveal the effect of incorporation of LTA into the lattice of ADP crystals. - Highlights: • LTA doped ADP crystals were grown for the first time. • Optical transmission was found to be higher at 1 mol% LTA doping. • SHG was found to be enhanced nonlinearly due to doping. • Thermal stability was found to higher at 1 mol% LTA doping. • Hardness was found to be increases with doping.

  14. Catalytic reduction of NO by methane using a Pt/C/polybenzimidazole/Pt/C fuel cell

    DEFF Research Database (Denmark)

    Petrushina, Irina; Cleemann, Lars Nilausen; Refshauge, Rasmus

    2007-01-01

    The catalytic NO reduction by methane was studied using a (NO,CH4,Ar),Pt|polybenzimidazole(PBI)–H3PO4|Pt,(H2,Ar) fuel cell at 135 and 165°C. It has been found that, without any reducing agent (like CH4), NO can be electrochemically reduced in the (NO, Ar), Pt/C|PBI–H3PO4|Pt/C, (H2,Ar) fuel cell...... NO reduction and introduced a dominant chemical path of the NO reduction. The products of the NO reduction with methane were N2, C2H4, and water. The catalytic NO reduction by methane was promoted when the catalyst was negatively polarized (−0.2 V). Repeated negative polarization of the catalyst increased...

  15. Polybenzimidazoles based on high temperature polymer electrolyte fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Linares Leon, Jose Joaquin; Camargo, Ana Paula M.; Ashino, Natalia M.; Morgado, Daniella L.; Frollini, Elisabeth; Paganin, Valdecir A.; Gonzalez, Ernesto Rafael [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil); Bajo, Justo Lobato [University of Castilla-La Mancha, Ciudad Real (Spain). Dept. of Chemical Engineering

    2010-07-01

    This work presents an interesting approach in order to enhance the performance of Polymer Electrolyte Membrane Fuel Cells (PEMFC) by means of an increase in the operational temperature. For this, two polymeric materials, Poly(2,5-bibenzimidazole) (ABPBI) and Poly[2,2'-(m-phenyl en)-5,5' bib enzimidazol] (PBI), impregnated with phosphoric acid have been utilized. These have shown excellent properties, such as thermal stability above 500 deg C, reasonably high conductivity when impregnated with H{sub 3}PO{sub 4} and a low permeability to alcohols compared to Nafion. Preliminary fuel cells measurements on hydrogen based Polymer Electrolyte Membrane Fuel Cell (PEMFC) displayed an interestingly reasonable good fuel cell performance, a quite reduced loss when the hydrogen stream was polluted with carbon monoxide, and finally, when the system was tested with an ethanol/water (E/W) fuel, it displayed quite promising results that allows placing this system as an attractive option in order to increase the cell performance and deal with the typical limitations of low temperature Nafion-based PEMFC. (author)

  16. Diazeniumdiolate-Doped Poly(lactic-co-glycolic acid)-Based Nitric Oxide Releasing Films as Antibiofilm Coatings

    Science.gov (United States)

    Cai, Wenyi; Wu, Jianfeng; Xi, Chuanwu; Meyerhoff, Mark, E.

    2012-01-01

    Nitric oxide (NO) releasing films with a bilayer configuration are fabricated by doping dibutyhexyldiamine diazeniumdiolate (DBHD/N2O2) in a poly(lactic-co-glycolic acid) (PLGA) layer and further encapsulating this base layer with a silicone rubber top coating. By incorporating pH sensitive dyes within the films, pH changes in the PLGA layer are visualized and correlated with the NO release profiles (flux vs. time). It is demonstrated that PLGA acts as both a promoter and controller of NO release from the coating by providing protons through its intrinsic acid residues (both end-groups and monomeric acid impurities) and hydrolysis products (lactic acid and glycolic acid). Control of the pH changes within the PLGA layer can be achieved by adjusting the ratio of DBHD/N2O2 and utilizing PLGAs with different hydrolysis rates. Coatings with a variety of NO release profiles are prepared with lifetimes of up to 15 d at room temperature (23 °C) and 10 d at 37 °C. When incubated in a CDC flow bioreactor for a one-week period at RT or 37 °C, all the NO releasing films exhibit considerable antibiofilm properties against gram-positive S. aureus and gram-negative E. coli. In particular, compared to the silicone rubber surface alone, an NO releasing film with a base layer of 30 wt% DBHD/N2O2 mixed with poly(lactic acid) exhibits an ~98.4% reduction in biofilm biomass of S. aureus and ~ 99.9% reduction for E. coli at 37 °C. The new diazeniumdiolate-doped PLGA-based NO releasing coatings are expected to be useful antibiofilm coatings for a variety of indwelling biomedical devices (e.g., catheters). PMID:22841918

  17. Inducing electrocatalytic functionality in ZnO thin film by N doping to realize a third generation uric acid biosensor.

    Science.gov (United States)

    Jindal, Kajal; Tomar, Monika; Gupta, Vinay

    2014-05-15

    A third generation uric acid biosensor has been developed by exploiting the electrocatalytic functionality of nitrogen (N) doped zinc oxide (ZnO:N) thin film matrix deposited using pulsed laser deposition technique. The electrochemistry of ZnO:N thin film based electrode is investigated by using electrochemical impedance spectroscopy and cyclic voltammetry. The obtained results demonstrate that nitrogen doping in ZnO matrix offers a striking electrocatalytic activity to the immobilized uricase towards the oxidation of analyte (uric acid) and promotes the direct transfer of electrons from active sites of enzyme onto the electrode without any mediator. In contrast to pure ZnO, ZnO:N (8% N) thin film based uric acid biosensor gives a high sensitivity of about 1.38 mA/mM in the absence of mediator. Moreover, ZnO:N derived bio-electrode exhibits excellent selectivity and outstanding analytical stability and reproducibility, which enables a reliable and sensitive determination of uric acid in the serum. The ZnO:N thin film based biosensor exhibits a linear sensing response in the range from 0 to 1.0mM of uric acid concentration and the apparent Michaelis-Menten kinetic parameter (Km) is estimated to be about 0.13 mM which indicates the high affinity of the prepared bio-electrode towards uric acid. The obtained results are encouraging and indicate that the ZnO:N thin film matrix offers a new and promising platform for the development of novel third generation biosensors without using any mediator. © 2013 Published by Elsevier B.V.

  18. Development of Polybenzimidazole-Based High-Temperature Membrane and Electrode Assemblies for Stationary and Automotive Applications

    Energy Technology Data Exchange (ETDEWEB)

    Vogel, John A.

    2008-09-03

    The program began on August 1, 2003 and ended on July 31, 2007. The goal of the project was to optimize a high-temperature polybenzimidazole (PBI) membrane to meet the performance, durability, and cost targets required for stationary fuel cell applications. These targets were identified in the Fuel Cell section (3.4) of DOE’s Hydrogen, Fuel Cells and Infrastructure Technologies Program Multi-Year Research, Development and Demonstration Plan. A membrane that operates at high temperatures is important to the fuel cell industry because it is insensitive to carbon monoxide (a poison to low-temperature fuel cells), and does not require complex water management strategies. Together, these two benefits greatly simplify the fuel cell system. As a result, the high-temperature fuel cell system realizes a cost benefit as the number of components is reduced by nearly 30%. There is also an inherent reliability benefit as components such as humidifiers and pumps for water management are unnecessary. Furthermore, combined heat and power (CHP) systems may be the best solution for a commercial, grid-connected, stationary product that must offer a cost benefit to the end user. For a low-temperature system, the quality of the heat supplied is insufficient to meet consumer needs and comfort requirements, so peak heaters or supplemental boilers are required. The higher operating temperature of PBI technology allows the fuel cell to meet the heat and comfort demand without the additional equipment. Plug Power, working with the Rensselaer Polytechnic Institute (RPI) Polymer Science Laboratory, made significant advances in optimizing the PBI membrane material for operation at temperatures greater than 160oC with a lifetime of 40,000 hours. Supporting hardware such as flow field plates and a novel sealing concept were explored to yield the lower-cost stack assembly and corresponding manufacturing process. Additional work was conducted on acid loss, flow field design and cathode electrode

  19. Effect of sorbic acid doping on flux pinning in bulk MgB{sub 2} with the percolation model

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y. [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Key Laboratory of Magnetic Levitation and Maglev Train (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Cheng, C.H. [School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia); Wang, L.; Sun, H.H. [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Key Laboratory of Magnetic Levitation and Maglev Train (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhao, Y., E-mail: yzhao@swjtu.edu.c [Key Laboratory of Advanced Technologies of Materials (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Key Laboratory of Magnetic Levitation and Maglev Train (Ministry of Education of China), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney, 2052 NSW (Australia)

    2010-11-01

    In this paper, we study the doping effect of sorbic acid (C{sub 6}H{sub 8}O{sub 2}), from 0 to 20 wt.% of the total MgB{sub 2}, on critical temperature (T{sub c}), critical current density (J{sub c}), irreversibility field (H{sub irr}) and crystalline structure. The XRD patterns of samples show a slightly decrease in a-axis lattice parameter for doped samples, due to the partial substitution of carbon at boron site. On the other hand, we investigate the influence of doping on the behavior of flux pinning and J{sub c}(B) in the framework of percolation theory and it is found that the J{sub c}(B) behavior could be well fitted in high field region. The two key parameters, anisotropy and percolation threshold, play very important roles. It is believed that the enhancement of J{sub c} is due to the reduction of anisotropy in high field region.

  20. Synthesis of Nickel (Ni) Doped HKUST-1 Using Solvotermal Method with Addition of Acetic Acid as Modulator

    OpenAIRE

    Safii, Farhan Fikri; Ediati, Ratna

    2015-01-01

    Hong Kong University of Science and Technology-1 (HKUST-1) is metal organic framework (MOF) that composed from ligand BTC (1,3,5-benzene tricarboxylic) and copper ions. The method used in this study is solvotermal with variations nickel ion doping and additions acetic acid as modulator. The purpose of this study is to increase the hydrogen storage capacity. The results obtained were characterized by XRD showed that the HKUST-1 and Ni-HKUST-1 has formed, showed by peaks at 2 theta = 6.7, 9.5, ...

  1. Electronic properties of electron-doped [6,6]-phenyl-C61-butyric acid methyl ester and silylmethylfullerene

    Science.gov (United States)

    Furutani, Sho; Okada, Susumu

    2017-06-01

    Electronic properties of electron-doped chemically decorated C60 fullerenes, [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and silylmethylfullerene (SIMEF), by a planar electrode were studied using density functional theory combined with the effective screening medium method to simulate the heterointerface between the chemically decorated C60 and cationic counter materials. We find that the distribution of accumulated electrons and induced electric field depend on the molecular arrangement with respect to the external electric field of the electrode. We also show that the quantum capacitance of the molecule is sensitive to molecular arrangement owing to the asymmetric distribution of the accumulated electrons.

  2. Metal-Free Nitrogen-Doped Carbon Foam Electrocatalysts for the Oxygen Reduction Reaction in Acid Solution

    OpenAIRE

    Liu, J.; Yu, S; Daio, T.; M. S. Ismail; Sasaki, K.; Lyth, S.M.

    2016-01-01

    Metal-free, nitrogen-doped carbon foam is utilized as a model non-precious electrocatalyst system to investigate the role of nitrogen in the oxygen reduction reaction (ORR) in the absence of iron contamination. This graphene-like foam displays relatively high activity for the ORR in acid, despite being proven free from transition-metal impurities. The onset potential is 0.85 VRHE, the mass activity is 2.8 A/g at 0.6 VRHE, and the current density is −4.0 mA/cm2. The maximum electron transfer n...

  3. Enhanced optical, thermal and piezoelectric behavior in dye doped potassium acid phthalate (KAP) single crystal

    Science.gov (United States)

    Rao, G. Babu; Rajesh, P.; Ramasamy, P.

    2017-06-01

    Dye inclusion crystals have attracted researchers in the context of crystal growth for applications in solid state lasers. Pure and 0.1 mol% amaranth doped KAP single crystals, were grown from aqueous solutions by slow evaporation technique at room temperature. The grown crystals are up to the dimension of 12×10×3 mm3. Attempt is made to improve the growth rate, optical, piezoelectric and photoconductive properties of pure KAP single crystal with addition of amaranth dye as a dopant. Various characterization studies were made for both pure and dye doped KAP. Thermal stability of the crystals is tested from thermogravimetric and differential thermal analysis (TG/DTA). There is only one endothermic peak indicating decomposition point. Higher optical transparency for dye doped KAP crystal was identified from the UV-vis spectrum. Etching studies showed an improvement in the optical quality of the KAP crystal after doping with amaranth dye. The positive photoconductive nature is observed from both pure and amaranth doped KAP.

  4. Highly efficient electrochemical degradation of perfluorooctanoic acid (PFOA) by F-doped Ti/SnO{sub 2} electrode

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Bo, E-mail: boyang@szu.edu.cn [Department of Environmental Engineering, College of Chemistry and Chemical Engineering, Shenzhen University, Shenzhen 518060 (China); School of Environment, POPs Research Center, Tsinghua University, Beijing 100084 (China); Jiang, Chaojin [Department of Environmental Engineering, College of Chemistry and Chemical Engineering, Shenzhen University, Shenzhen 518060 (China); Yu, Gang, E-mail: yg-den@tsinghua.edu.cn [School of Environment, POPs Research Center, Tsinghua University, Beijing 100084 (China); Zhuo, Qiongfang [South China Institute of Environmental Sciences, The Ministry of Environment Protection, Guangzhou 510655 (China); Deng, Shubo [School of Environment, POPs Research Center, Tsinghua University, Beijing 100084 (China); Wu, Jinhua [School of Environment and Energy, South China University of Technology, Guangzhou 510006 (China); Zhang, Hong [Department of Environmental Engineering, College of Chemistry and Chemical Engineering, Shenzhen University, Shenzhen 518060 (China)

    2015-12-15

    Highlights: • A novel SnO{sub 2} electrode is prepared by F doping instead of the traditional Sb doping. • SnF{sub 4} as single-source precursor is used to fabricate the long-life Ti/SnO{sub 2}–F anode. • F-doped Ti/SnO{sub 2} anode possesses high OEP and decomposition ability for PFOA. • Further mechanistic detail of PFOA degradation on Ti/SnO{sub 2}–F electrode is proposed. - Abstract: The novel F-doped Ti/SnO{sub 2} electrode prepared by SnF{sub 4} as the single-source precursor was used for electrochemical degradation of aqueous perfluorooctanoic acid (PFOA). Higher oxidation reactivity and significantly longer service life were achieved for Ti/SnO{sub 2}–F electrode than Ti/SnO{sub 2}–X (X = Cl, Br, I, or Sb) electrode, which could decomposed over 99% of PFOA (50 mL of 100 mg L{sup −1}) within 30-min electrolysis. The property of Ti/SnO{sub 2}–F electrode and its electrooxidation mechanism were investigated by XRD, SEM–EDX, EIS, LSV, and interfacial resistance measurements. We propose that the similar ionic radii of F and O as well as strong electronegativity of F caused its electrochemical stability with high oxygen evolution potential (OEP) and smooth surface to generate weakly adsorbed ·OH. The preparation conditions of electrode were also optimized including F doping amount, calcination temperature, and dip coating times, which revealed the formation process of electrode. Additionally, the major mineralization product, F{sup −}, and low concentration of shorter chain perfluorocarboxylic acids (PFCAs) were detected in solution. So the reaction pathway of PFOA electrooxidation was proposed by intermediate analysis. These results demonstrate that Ti/SnO{sub 2}–F electrode is promising for highly efficient treatment of PFOA in wastewater.

  5. Long-term testing of a high-temperature proton exchange membrane fuel cell short stack operated with improved polybenzimidazole-based composite membranes

    Science.gov (United States)

    Pinar, F. Javier; Cañizares, Pablo; Rodrigo, Manuel A.; Úbeda, Diego; Lobato, Justo

    2015-01-01

    In this work, the feasibility of a 150 cm2 high-temperature proton exchange membrane fuel cell (HT-PEMFC) stack operated with modified proton exchange membranes is demonstrated. The short fuel cell stack was manufactured using a total of three 50 cm2 membrane electrode assemblies (MEAs). The PEM technology is based on a polybenzimidazole (PBI) membrane. The obtained results were compared with those obtained using a HT-PEMFC stack with unmodified membranes. The membranes were cast from a PBI polymer synthesized in the laboratory, and the modified membranes contained 2 wt.% micro-sized TiO2 as a filler. Long-term tests were performed in both constant and dynamic loading modes. The fuel cell stack with 2 wt.% TiO2 composite PBI membranes exhibited an irreversible voltage loss of less than 2% after 1100 h of operation. In addition, the acid loss was reduced from 2% for the fuel cell stack with unmodified membranes to 0.6% for the fuel cell stack with modified membranes. The results demonstrate that introducing filler into the membranes enhances the durability and stability of this type of fuel cell technology. Moreover, the fuel cell stack system also exhibits very rapid and stable power and voltage output responses under dynamic load regimes.

  6. Single-Atomic Ruthenium Catalytic Sites on Nitrogen-Doped Graphene for Oxygen Reduction Reaction in Acidic Medium.

    Science.gov (United States)

    Zhang, Chenhao; Sha, Junwei; Fei, Huilong; Liu, Mingjie; Yazdi, Sadegh; Zhang, Jibo; Zhong, Qifeng; Zou, Xiaolong; Zhao, Naiqin; Yu, Haisheng; Jiang, Zheng; Ringe, Emilie; Yakobson, Boris I; Dong, Juncai; Chen, Dongliang; Tour, James M

    2017-07-25

    The cathodic oxygen reduction reaction (ORR) is essential in the electrochemical energy conversion of fuel cells. Here, through the NH3 atmosphere annealing of a graphene oxide (GO) precursor containing trace amounts of Ru, we have synthesized atomically dispersed Ru on nitrogen-doped graphene that performs as an electrocatalyst for the ORR in acidic medium. The Ru/nitrogen-doped GO catalyst exhibits excellent four-electron ORR activity, offering onset and half-wave potentials of 0.89 and 0.75 V, respectively, vs a reversible hydrogen electrode (RHE) in 0.1 M HClO4, together with better durability and tolerance toward methanol and carbon monoxide poisoning than seen in commercial Pt/C catalysts. X-ray adsorption fine structure analysis and aberration-corrected high-angle annular dark-field scanning transmission electron microscopy are performed and indicate that the chemical structure of Ru is predominantly composed of isolated Ru atoms coordinated with nitrogen atoms on the graphene substrate. Furthermore, a density function theory study of the ORR mechanism suggests that a Ru-oxo-N4 structure appears to be responsible for the ORR catalytic activity in the acidic medium. These findings provide a route for the design of efficient ORR single-atom catalysts.

  7. Au/ZnO hybrid nanocatalysts impregnated in N-doped graphene for simultaneous determination of ascorbic acid, acetaminophen and dopamine.

    Science.gov (United States)

    Chen, Xianlan; Zhang, Guowei; Shi, Ling; Pan, Shanqing; Liu, Wei; Pan, Hiabo

    2016-08-01

    The formation of nitrogen-doped (N-doped) graphene uses hydrothermal method with urea as reducing agent and nitrogen source. The surface elemental composition of the catalyst was analyzed through XPS, which showed a high content of a total N species (7.12at.%), indicative of the effective N-doping, present in the form of pyridinic N, pyrrolic N and graphitic N groups. Moreover, Au nanoparticles deposited on ZnO nanocrystals surface, forming Au/ZnO hybrid nanocatalysts, undergo a super-hydrophobic to super-hydrophilic conversion. Herein, we present Au/ZnO hybrid nanocatalysts impregnated in N-doped graphene sheets through sonication technique of the Au/ZnO/N-doped graphene hybrid nanostructures. The as-prepared Au/ZnO/N-doped graphene hybrid nanostructure modified glassy carbon electrode (Au/ZnO/N-doped graphene/GCE) was first employed for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and acetaminophen (AC). The oxidation over-potentials of AA, DA and AC decreased dramatically, and their oxidation peak currents increased significantly at Au/ZnO/N-doped graphene/GCE compared to those obtained at the N-doped graphene/GCE and bare CCE. The peak separations between AA and DA, DA and AC, and AC and AA are large up to 195, 198 and 393mV, respectively. The calibration curves for AA, DA and AC were obtained in the range of 30.00-13.00×10(3), 2.00-0.18×10(3) and 5.00-3.10×10(3)μM, respectively. The detection limits (S/N=3) were 5.00, 0.40 and 0.80μM for AA, DA and AC, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Exceptional durability enhancement of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200°C

    DEFF Research Database (Denmark)

    Aili, David; Zhang, Jin; Jakobsen, Mark Tonny Dalsgaard

    2016-01-01

    The incorporation of phosphotungstic acid functionalized mesoporous silica in phosphoric acid doped polybenzimidazole (PA/PBI) substantially enhances the durability of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200°C.......The incorporation of phosphotungstic acid functionalized mesoporous silica in phosphoric acid doped polybenzimidazole (PA/PBI) substantially enhances the durability of PA/PBI based polymer electrolyte membrane fuel cells for high temperature operation at 200°C....

  9. Polylactic acid-based porous scaffolds doped with calcium silicate and dicalcium phosphate dihydrate designed for biomedical application.

    Science.gov (United States)

    Gandolfi, Maria Giovanna; Zamparini, Fausto; Degli Esposti, Micaela; Chiellini, Federica; Aparicio, Conrado; Fava, Fabio; Fabbri, Paola; Taddei, Paola; Prati, Carlo

    2018-01-01

    Polylactic acid (PLA), dicalcium phosphate dihydrate (DCPD) and/or hydraulic calcium silicate (CaSi) have been used to prepare highly-porous scaffolds by thermally induced phase separation technique (TIPS). Three experimental mineral-doped formulations were prepared (PLA-10CaSi, PLA-5CaSi-5DCPD, PLA-10CaSi-10DCPD). Pure PLA scaffolds constituted the control group. Scaffolds were tested for their chemical-physical and biological properties, namely calcium release, alkalinizing activity, surface microchemistry and micromorphology by ESEM, apatite-forming ability by EDX, micro-Raman and IR spectroscopy, thermal properties by differential scanning calorimetry, mechanical properties by quasi-static parallel-plates compression testing, porosity by a standard water-absorption method and direct-contact cytotoxicity. All mineral-doped scaffolds released biologically relevant ions (biointeractive). A B-type carbonated apatite layer (thickness decreasing along the series PLA-10CaSi-10DCPD>PLA-10CaSi>PLA-5CaSi-5DCPD>PLA) was detected on the surface of all the 28d-aged scaffolds. Surface pores of fresh scaffolds ranged from 10 to 20μm in pure PLA to 10-100μm in PLA-10CaSi. An increase in porosity was detected in 28d-aged pure PLA scaffolds (approx. 30% of material loss with decrease of the PLA chain length); differently, in mineral-doped scaffolds, the PLA degradation was balanced by deposition/nucleation of apatite. All scaffolds showed absence of toxicity, in particular PLA-10CaSi-10DCPD. The designed scaffolds are biointeractive (release biologically relevant ions), nucleate apatite, possess high surface and internal open porosity and can be colonized by cells, appearing interesting materials for bone regeneration. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Nitrogen-doped carbon-TiO2 composite as support of Pd electrocatalyst for formic acid oxidation

    Science.gov (United States)

    Qin, Yuan-Hang; Li, Yunfeng; Lam, Thomas; Xing, Yangchuan

    2015-06-01

    We report Pd nanoparticles supported on a composite consisting of oxide TiO2 and nitrogen-doped carbon for formic acid oxidation (FAO). The nitrogen-doped carbon-TiO2 (NCx-TiO2) composite support was prepared by a simple polymerization-pyrolysis process using commercial TiO2 nanoparticles (P25). Surface analysis showed that elements of Ti, C, O, and N were present on the composite surface, on which nitrogen existed in both pyridinic and quaternary forms. Pd nanoparticles with a mean size of ca. 4 nm were uniformly deposited on the composite via a polyol process. Electrochemical characterizations showed that the NCx-TiO2-supported Pd particles (Pd/NCx-TiO2) exhibited an electrocatalytic activity towards FAO that almost doubled that of the carbon black-supported Pd particles (Pd/C) with much enhanced electrocatalytic stability. The better performance of the composite supported Pd was attributed to a possible electronic structure modification in the metallic Pd particles and bifunctional effect produced by the NCx-TiO2 composite.

  11. Experimental characterization and modeling of commercial polybenzimidazole-based MEA performance

    DEFF Research Database (Denmark)

    Korsgaard, Anders; Refshauge, R. H.; Nielsen, Mads Pagh

    2006-01-01

    High temperature polymer fuel cells based on polybenzimidazole membranes (PBI) operated at 100-200 °C are currently receiving much attention in relation to fuel cell reforming systems due to two main reasons. At first they have proven to have excellent resistance to high CO concentrations, which...... are currently published to enable good system design and modeling. In this paper the influence of operation on synthesis gas and the variation of the cathode stoichiometry are investigated based on a generic commercial membrane electrode assembly (MEA). The CO content in the anode gas was varied from 0 to 5......%, with CO2 contents ranging from 25 to 20% at temperatures ranging from 160 to 200 °C. The influence of the cathode stoichiometry was investigated in the interval of 2-5 at temperatures from 120 to 180 °C with pure hydrogen on the anode. A novel semi empirical model of the fuel cell voltage versus current...

  12. Enhanced forward osmosis from chemically modified polybenzimidazole (PBI) nanofiltration hollow fiber membranes with a thin wall

    KAUST Repository

    Wang, Kai Yu

    2009-04-01

    To develop high-flux and high-rejection forward osmosis (FO) membranes for water reuses and seawater desalination, we have fabricated polybenzimidazole (PBI) nanofiltration (NF) hollow fiber membranes with a thin wall and a desired pore size via non-solvent induced phase inversion and chemically cross-linking modification. The cross-linking by p-xylylene dichloride can finely tune the mean pore size and enhance the salt selectivity. High water permeation flux and improved salt selectivity for water reuses were achieved by using the 2-h modified PBI NF membrane which has a narrow pore size distribution. Cross-linking at a longer time produces even a lower salt permeation flux potentially suitable for desalination but at the expense of permeation flux due to tightened pore sizes. It is found that draw solution concentration and membrane orientations are main factors determining the water permeation flux. In addition, effects of membrane morphology and operation conditions on water and salt transport through membrane have been investigated. © 2008 Elsevier Ltd. All rights reserved.

  13. Enhanced selectivity of boron doped diamond electrodes for the detection of dopamine and ascorbic acid by increasing the film thickness

    Science.gov (United States)

    Qi, Yao; Long, Hangyu; Ma, Li; Wei, Quiping; Li, Site; Yu, Zhiming; Hu, Jingyuan; Liu, Peizhi; Wang, Yijia; Meng, Lingcong

    2016-12-01

    In this paper, boron doped diamond (BDD) with different thickness were prepared by hot filament chemical vapor deposition. The performance of BDD electrodes for detecting dopamine (DA) and ascorbic acid (AA) were investigated. Scanning electron microscopy and Raman spectra reveal the grain size increases and the film quality improves with the increase of film thickness. Electrochemical test show that the transfer coefficient in [Fe3 (CN) 6]3-/4- redox system increases with the increase of the film thickness. The results of selectivity and sensitivity for DA mixed with AA detection show that 8h-BDD and 12h-BDD electrodes possess well selective separated oxidation peaks of DA and AA, and the 12h-BDD electrode exhibits optimal sensitivity until the DA concentration drops to 1 μ M.

  14. Antibacterial Property and Cytotoxicity of a Poly(lactic acid/Nanosilver-Doped Multiwall Carbon Nanotube Nanocomposite

    Directory of Open Access Journals (Sweden)

    Chi-Hui Tsou

    2017-03-01

    Full Text Available A novel method was used to synthesize a nanosilver-doped multiwall carbon nanotube (MWCNT-Ag, and subsequently, the novel poly(lactic acid (PLA- and MWCNT-Ag-based biocompatible and antimicrobial nanocomposites were prepared by melt blending. Based on energy dispersive X-ray spectrometry images, an MWCNT-Ag was successfully synthesized. The effect of the MWCNT-Ag on the PLA bionanocomposites was investigated by evaluating their thermal and mechanical properties, antifungal activity, and cytotoxicity. The nanocomposites exhibited a high degree of biocompatibility with the MWCNT-Ag content, which was less than 0.3 phr. Furthermore, tensile strength testing, thermogravimetric analysis, differential scanning calorimetry, and antibacterial evaluation revealed that the tensile strength, thermostability, glass transition temperature, and antibacterial properties were enhanced by increasing the MWCNT-Ag content. Finally, hydrolysis analysis indicated that the low MWCNT-Ag content could increase the packing density of PLA.

  15. Dual responsive dysprosium-doped hydroxyapatite particles and toxicity reduction after functionalization with folic and glucuronic acids.

    Science.gov (United States)

    Sánchez Lafarga, Ana Karen; Pacheco Moisés, Fermín P; Gurinov, Andrey; Ortiz, Genaro Gabriel; Carbajal Arízaga, Gregorio Guadalupe

    2015-03-01

    The development of probes for biomedical applications demands materials with low toxicity levels besides fluorescence or magnetic properties to be detected by confocal microscopes or MRI resonators. Several drug delivery systems or other biomedical materials prepared with hydroxyapatite have been proposed, however, toxicity effects might arise when the size of particles is nanometric. In this study, hydroxyapatite functionalized with glucuronic or folic acids presented lower oxidative stress, measured from lipoperoxides and nitric oxide indicators in rats than pure hydroxyapatite. In separated experiments, hydroxyapatite was doped with dysprosium cations by coprecipitation producing a single crystal phase with fluorescent properties easily visualized by confocal microscopy when excited at 488nm. These particles also presented the ability to modify the proton relaxation time in T1 maps collected by magnetic resonance imaging. These modified hydroxyapatite nanoparticles could be candidates to design bimodal probes with low toxicity. Copyright © 2014 Elsevier B.V. All rights reserved.

  16. Tannic acid functionalized N-doped graphene modified glassy carbon electrode for the determination of bisphenol A in food package.

    Science.gov (United States)

    Jiao, Shoufeng; Jin, Jing; Wang, Lun

    2014-05-01

    A rapid, environmental friendly, and sensitive sensor for the detection of bisphenol A (BPA) was developed at glassy carbon electrode (GCE) modified with Tannic acid functionalized N-doped graphene (TA/N-G) immobilized by Nafion. Compared with other sensors, the proposed sensor greatly enhanced the response signal of BPA due to the active surface area of N-G and high absorption efficiency of TA. Under the optimal conditions, the oxidation current increased linearly with increasing the concentration of BPA in the range of 0.05-13 µM with the detection limit of 4.0 nM. The fabricated electrode showed good reproducibility, stability and anti-interference. The developed electrochemical sensor was successfully applied to determine BPA in food package. Copyright © 2014 Elsevier B.V. All rights reserved.

  17. Chemometric study on the electrochemical incineration of nitrilotriacetic acid using platinum and boron-doped diamond anode.

    Science.gov (United States)

    Zhang, Chunyong; He, Zhenzhu; Wu, Jingyu; Fu, Degang

    2015-07-01

    This study investigated the electrochemical incineration of nitrilotriacetic acid (NTA) at boron-doped diamond (BDD) and platinum (Pt) anodes. Trials were performed in the presence of sulfate electrolyte media under recirculation mode. The parameters that influence the degradation efficiency were investigated, including applied current density, flow rate, supporting electrolyte concentration and reaction time. To reduce the number of experiments, the system had been managed under chemometric technique named Doehlert matrix. As a consequence, the mineralization of NTA demonstrated similar behavior upon operating parameters on these two anodes. Further kinetic study indicated that the degradations followed pseudo-first-order reactions for both BDD and Pt anodes, and the reaction rate constant of the former was found to be higher than that of the latter. Such difference could be interpreted by results from fractal analysis. In addition, a reaction sequence for NTA mineralization considering all the detected intermediates was also proposed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  18. Proton conducting membranes based on benzimidazole sulfonic acid doped sulfonated poly(oxadiazole-triazole) copolymer for low humidity operation

    Energy Technology Data Exchange (ETDEWEB)

    Boaventura, M.; Mendes, A.; Madeira, L.M. [LEPAE - Laboratorio de Engenharia de Processos Ambiente e Energia, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias s/n, 4200-465 Porto (Portugal); Gomes, D.; Nunes, S.P. [GKSS Research Centre Geesthacht GmbH, Max Planck Str. 1, D-21502, Geesthacht (Germany); Ponce, M.L.

    2008-07-15

    This work reports for the first time the preparation of sulphonated poly(oxadiazole-triazole) copolymer membranes doped with amphoteric molecule, 1H-benzimidazole-2-sulphonic acid and their characterisation as proton conductors at 120 C and low humidity. The membranes had not only high proton conductivities, up to 4 x 10{sup -3} S cm{sup -1} at 120 C and low relative humidity (5 and 10%), but also had good mechanical properties with a storage modulus of about 3 GPa at 300 C and high thermal stability with T{sub g} up to around 420 C. Because of their superior ion conducting and mechanical properties they have potential as a proton conducting membrane for fuel cell applications, in particular at high temperature and extremely low-humidity conditions. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

  19. Synthesis, characterization and visible light photocatalytic activity of Cr 3+ , Ce 3+ and N co-doped TiO 2 for the degradation of humic acid

    KAUST Repository

    Rashid, S. G.

    2015-01-01

    The synthesis, characterization and photocatalytic activity of Cr3+ and Ce3+ co-doped TiON (N-doped TiO2) for the degradation of humic acid with exposure to visible light is reported. The synthesized bimetal (Cr3+ + Ce3+) modified TiON (Cr-Ce/TiON), with an evaluated bandgap of 2.1 eV, exhibited an enhanced spectral response in the visible region as compared to pure and Ce3+ doped TiON (Ce/TiON). The XRD analysis revealed the insertion of Cr3+ and Ce3+ in the crystal lattice along with Ti4+ and N that resulted in the formation of a strained TiON anatase structure with an average crystallite size of ∼10 nm. Raman analysis also supported the formation of stressed rigid structures after bimetal doping. HRTEM confirmed the homogeneous distribution of both the doped metallic components in the crystal lattice of TiON without the formation of surface oxides of either Cr3+ or Ce3+. Electron energy loss spectroscopy (EELS) analysis revealed no change in the oxidation of either Cr or Ce during the synthesis. The synthesized Cr-Ce/TiON catalyst exhibited appreciable photocatalytic activity for the degradation of humic acid on exposure to visible light. Additionally, a noticeable mineralization of carbon rich humic acid was also witnessed. The photocatalytic activity of the synthesized catalyst was compared with pristine and Ce3+ doped TiON. © The Royal Society of Chemistry 2015.

  20. A novel fluorescence biosensor for sensitivity detection of tyrosinase and acid phosphatase based on nitrogen-doped graphene quantum dots.

    Science.gov (United States)

    Qu, Zhengyi; Na, Weidan; Liu, Xiaotong; Liu, Hua; Su, Xingguang

    2018-01-02

    In this paper, we developed a sensitive fluorescence biosensor for tyrosinase (TYR) and acid phosphatase (ACP) activity detection based on nitrogen-doped graphene quantum dots (N-GQDs). Tyrosine could be catalyzed by TYR to generate dopaquinone, which could efficiently quench the fluorescence of N-GQDs, and the degree of fluorescence quenching of N-GQDs was proportional to the concentration of TYR. In the presence of ACP, l-Ascorbic acid-2-phosphate (AAP) was hydrolyzed to generate ascorbic acid (AA), and dopaquinone was reduced to l-dopa, resulting in the fluorescence recovery of the quenched fluorescence by dopaquinone. Thus, a novel fluorescence biosensor for the detection of TYR and ACP activity based on N-GQDs was constructed. Under the optimized experimental conditions, the fluorescence intensity was linearly correlated with the concentration of TYR and ACP in the range of 0.43-3.85 U mL-1 and 0.04-0.7 mU mL-1 with a detection limit of 0.15 U mL-1 and 0.014 mU mL-1, respectively. The feasibility of the proposed biosensor in real samples assay was also studied and satisfactory results were obtained. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. Fabrication and characterization of conductive poly (3,4-ethylenedioxythiophene) doped with hyaluronic acid/poly (l-lactic acid) composite film for biomedical application.

    Science.gov (United States)

    Wang, Shuping; Guan, Shui; Wang, Jing; Liu, Hailong; Liu, Tianqing; Ma, Xuehu; Cui, Zhanfeng

    2017-01-01

    Poly 3,4-ethylenedioxythiophene (PEDOT), a polythiophene derivative, has been proved to be modified by chemical process as biocompatible conductive polymer for biomedical applications. In this study, novel hyaluronic acid (HA)-doped PEDOT nanoparticles were synthesized by the method of chemical oxidative polymerization, then conductive PEDOT-HA/poly(l-lactic acid) (PLLA) composite films were prepared. The physicochemical characteristics and biocompatibility of films were further investigated. FTIR, Raman and EDX analysis demonstrated that HA was successfully doped into PEDOT particles. Cyclic voltammograms indicated PEDOT-HA particles had favorable electrochemical stability. PEDOT-HA/PLLA films showed lower surface contact angle and faster degradation degree compared with PLLA films. Moreover, the cytotoxicity test of PEDOT-HA/PLLA films showed that neuron-like pheochromocytoma (PC12) cells adhered and spread well on the surface of PEDOT-HA/PLLA films and cell viability denoted by MTT assay had a significant increase. PEDOT-HA/PLLA films modified with laminin (LN) also exhibited an efficiently elongated cell morphology observed by fluorescent microscope and metallographic microscope. Furthermore, PEDOT-HA/PLLA films were subjected to different current intensity to elucidate the effect of electrical stimulation (ES) on neurite outgrowth of PC12 cells. ES (0.5 mA, 2 h) significantly promoted neurite outgrowth with an average value length of 122 ± 5 μm and enhanced the mRNA expression of growth-associated protein (GAP43) and synaptophysin (SYP) in PC12 cells when compared with other ES groups. These results suggest that PEDOT-HA/PLLA film combined with ES are conducive to cell growth and neurite outgrowth, indicating the conductive PEDOT-HA/PLLA film may be an attractive candidate with ES for enhancing nerve regeneration in nerve tissue engineering. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  2. Simultaneous voltammetric determination of paracetamol and ascorbic acid using a boron-doped diamond electrode modified with Nafion and lead films.

    Science.gov (United States)

    Tyszczuk-Rotko, Katarzyna; Bęczkowska, Ilona; Wójciak-Kosior, Magdalena; Sowa, Ireneusz

    2014-11-01

    The paper describes the fabrication and application of a novel sensor (a boron-doped diamond electrode modified with Nafion and lead films) for the simultaneous determination of paracetamol and ascorbic acid by differential pulse voltammetry. The main advantage of the lead film and polymer covered boron-doped diamond electrode is that the sensitivity of the stripping responses is increased and the separation of paracetamol and ascorbic acid signals is improved due to the modification of the boron-doped diamond surface by the lead layer. Additionally, the repeatability of paracetamol and ascorbic acid signals is improved by the application of the Nafion film coating. In the presence of oxygen, linear calibration curves were obtained in a wide concentration range from 5×10(-7) to 2×10(-4) mol L(-1) for paracetamol and from 1×10(-6) to 5×10(-4) mol L(-1) for ascorbic acid. The analytical utility of the differential pulse voltammetric method elaborated was tested in the assay of paracetamol and ascorbic acid in commercially available pharmaceutical formulations and the method was validated by high performance liquid chromatography coupled with diode array detector. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Effect of doping of KDP crystal with amino acid L-arginine on the strength properties and character of laser damage

    Science.gov (United States)

    Dolzhenkova, E. F.; Kostenyukova, E. I.; Bezkrovnaya, O. N.; Pritula, I. M.

    2017-11-01

    Studied were the strength characteristics of KDP crystals doped with L-arginine under a concentrated load and irradiation of the first harmonic YAG:Nd3+ laser. The crystals were obtained by means of the temperature reduction method on a point seed, the content of L-arginine in the aqueous solution being 0.3, 0.4, 1.0 and 1.4 wt%. The character of the dependence of KDP microhardness versus the concentration of amino acid in the crystal was investigated. The regularities of brittle damage of the doped KDP crystal at mechanical testing and laser irradiation were shown to be similar. As confirmed in the study, the planes of easy crack extension in the crystal are {2 2 1}, (1 0 0), and (0 0 1) planes, the cracks mainly propagate parallel to {2 2 1} planes. The mechanical and laser strength values of doped KDP crystals were evaluated.

  4. Preparation and characterization of 5-sulphosalicylic acid doped tetraethoxysilane composite ion-exchange material by sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Suhail-ul; Islam, Nasarul; Ahad, Sozia; Fatima, Syed Zeeshan; Pandith, Altaf Hussain, E-mail: altafpandit23@gmail.com

    2013-09-15

    Highlights: • Sulphosalicylic acid doped tetraethoxysilane composite is prepared by sol–gel method. •Its X-ray diffraction studies suggest that it is crystalline in nature. • This material shows selectivity for Mg(II) and Ni(II) ions in aqueous solutions. • Separation of Ni(II) from binary mixtures was successfully achieved on this material. -- Abstract: In this manuscript, we report the preparation and characterization of sulphosalicylic doped tetraethoxysilane (SATEOS), composite material by sol–gel method as a new ion exchanger for the removal of Ni(II) from aqueous solution. The fine granular material was prepared by acid catalyzed condensation polymerization through sol–gel mechanism in the presence of cationic surfactant. The material has an ion exchange capacity of 0.64 mequiv./g(dry) for sodium ions, 0.60 mequiv./g(dry) for potassium ions, 1.84 mequiv./g(dry) for magnesium ions, 1.08 mequiv./g(dry) for calcium ions and 1.36 mequiv./g(dry) for strontium ions. Its X-ray diffraction studies suggest that it is crystalline in nature. The material has been characterized by SEM, IR, TGA and DTG so as to identify the various functional groups and ion exchange sites present in this material. Quantum chemical computations at DFT/B3LYP/6-311G (d,p) level on model systems were performed to substantiate the structural conclusions based ion instrumental techniques. Investigations into the elution behaviour, ion exchange reversibility and distribution capacities of this material towards certain environmentally hazardous metal ions are also performed. The material shows good chemical stability towards acidic conditions and exhibits fast elution of exchangeable H{sup +} ions under neutral conditions. This material shows remarkable selectivity for Ni(II) and on the basis of its K{sub d} value (4 × 10{sup 2} in 0.01 M HClO{sub 4}) some binary separations of Ni(II) from other metal ions are performed.

  5. Effect of adding Nanoclay (Cloisite-30B on the Proton Conductivity of Sulfonated Polybenzimidazole

    Directory of Open Access Journals (Sweden)

    Hashem Ahmadizadegan

    2017-01-01

    Full Text Available A novel sulfonated polybenzimidazole/organoclay (Cloisite-30B (SPBI/clay nanocomposite membranes was successfully synthesized based on aromatic diacide (1 and diaminobenzidine. Nanocomposite membranes were fabricated using 1, 4-bis (hydroxymethyl benzene (BHMB as cross-linker, and Cloisite-30B organoclay as the pseudo cross-linker. The cross-linked SPBI/clay nanocomposite membranes were prepared via solution intercalation method. Participation of reactive organoclay in the cross-linking process was established from ion exchange capacity (IEC measurements and FTIR studies. Wide angle X-ray diffraction (WAXD, field emission-scanning electron microscopy (FE-SEM, and transmission electron microscopy (TEM techniques confirmed the presence of a combination of the intercalated and partially exfoliated clay confirmed mixed clay dispersion morphology of intercalation and partial exfoliation of the clay platelets in the cross-linked SPBI/clay nanocomposite membrane. The cross-linked SPBI/clay nanocomposite membranes showed higher tensile strength, modulus and lower elongation at break compared to neat cross-linked SPBI. Water and methanol uptake studies revealed superior barrier properties of cross-linked SPBI/clay nanocomposite membranes compared to cross-linked SPBI. Furthermore, thermal stability, residual solvent in the membrane film, and structural ruination of membranes were analyzed by thermal gravimetric analysis (TGA. TGA data indicated an increase in thermal stability of the SPBI/clay nanocomposite membranes in compared to the pure polymer. The oxidative stability of SPBI improved remarkably with cross-linking and subsequent clay addition. These improvements in the thermo-mechanical, barrier and oxidative stability of the membranes could be achieved without significantly affecting the protonic conductivity.

  6. Preparation of ionic liquid-modified SBA-15 doped with molybdovanadophosphoric acid for oxidative desulfurization

    Energy Technology Data Exchange (ETDEWEB)

    Zhuang, Jiang Zhou; Jin, Xiao Yin; Shen, Xian Lin; Tan, Jun Jun; Nie, Long Hui; Xiang, Jian; Hu, Bing [Dept. of chool of Chemistry and Chemical Engineering, Hubei University of Technology, Wuhan (China)

    2015-07-15

    A series of catalysts, ionic liquid-modified SBA-15 (denoted ILSBA) doped with H{sub 5}PMo{sub 10}V{sub 2}O{sub 40} (HPMoV{sub 2}) have been synthesized and characterized by XRD, FT-IR, {sup 1}H NMR, TG-DTA, and TEM. The catalyst was used for the removal of dibenzothiophene (DBT) in model oil combined with hydrogen peroxide (the oxidant) and acetonitrile (the phase-transfer agent). It was observed that the sulfur content of DBT can be reduced from 500 to 2 ppm by adjusting the amount of catalyst, the reaction temperatures and the reaction time. Besides, the catalyst activity for different sulfur compounds showed a huge difference which may be mainly affected by the electron densities of sulfur atom. Moreover, the catalyst can be recycled seven times without a significant loss in activity, which could be ascribed to the strong electrostatic interaction between ILSBA and HPMoV{sub 2}. In addition, a postulated mechanism was proposed to reveal the oxidative desulfurization process.

  7. Phosphoric acid doped polysulfone membranes with aminopyridine pendant groups and imidazole cross-links

    DEFF Research Database (Denmark)

    Hink, Steffen; Elsøe, Katrine; Cleemann, Lars Nilausen

    2015-01-01

    Udel polysulfone based membranes with 4-aminopyridine pendant groups and cross-linking imidazole units are synthesized in a simple two step reaction. The ratio of 4-aminopyridine and imidazole is varied and the materials are extensively characterized. The average phosphoric acid uptake (in 85 wt...... tests at 130 °C. The relationships between PA uptake, chemical composition and mechanical stability are reported. Proton conductivity and mechanical properties only depend on the phosphoric acid content, which, however is a function of the chemical composition....

  8. Simultaneous cross-linking and p-doping of a polymeric semiconductor film by immersion into a phosphomolybdic acid solution for use in organic solar cells.

    Science.gov (United States)

    Aizawa, Naoya; Fuentes-Hernandez, Canek; Kolesov, Vladimir A; Khan, Talha M; Kido, Junji; Kippelen, Bernard

    2016-03-07

    Poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) is shown to be simultaneously cross-linked and p-doped when immersed into a phosphomolybdic acid solution, yielding conductive films with low solubility that can withstand the solution processing of subsequent photoactive layers. Such a modified PCDTBT film serves to improve hole collection and limit carrier recombination in organic solar cells.

  9. Highly water-dispersible, mixed ionic-electronic conducting, polymer acid-doped polyanilines as ionomers for direct methanol fuel cells.

    Science.gov (United States)

    Murthy, Arun; Manthiram, Arumugam

    2011-06-28

    Highly water-dispersible polymer acid-doped polyanilines have been synthesized and evaluated as an alternative for expensive Nafion ionomers in the anode of direct methanol fuel cells (DMFC). These polymers as ionomers lead to higher performance in single cell DMFC compared to Nafion ionomers due to mixed ionic-electronic conduction, water dispersibility, and co-catalytic activity. This journal is © The Royal Society of Chemistry 2011

  10. A Doped Polyaniline Modified Electrode Amperometric Biosensor for Gluconic Acid Determination in Grapes

    Directory of Open Access Journals (Sweden)

    Donatella Albanese

    2014-06-01

    Full Text Available In winemaking gluconic acid is an important marker for quantitative evaluation of grape infection by Botrytis cinerea. A screen-printed amperometric bienzymatic sensor for the determination of gluconic acid based on gluconate kinase (GK and 6-phospho-D-gluconate dehydrogenase (6PGDH coimmobilized onto polyaniline/poly (2-acrylamido-2-methyl-1-propanesulfonic acid; PANI-PAAMPSA is reported in this study. The conductive polymer electrodeposed on the working electrode surface allowed the detection of NADH at low potential (0.1 V with a linear range from 4 × 10−3 to 1 mM (R2 = 0.99 and a sensitivity of 419.44 nA∙mM−1. The bienzymatic sensor has been optimized with regard to GK/6PGDH enzymatic unit ratio and ATP/NADP+ molar ratio which resulted equal to 0.33 and 1.2, respectively. Under these conditions a sensitivity of 255.2 nA∙mM−1, a limit of detection of 5 μM and a Relative Standard Deviation (RSD of 4.2% (n = 5 have been observed. Finally, the biosensor has been applied for gluconic acid measurements in must grape samples and the matrix effect has been taken into consideration. The results have been compared with those obtained on the same samples with a commercial kit based on a spectrophotometric enzyme assay and were in good agreement, showing the capability of the bienzymatic PANI-PAAMPSA biosensor for gluconic acid measurements and thus for the evaluation of Botrytis cinerea infection in grapes.

  11. Surface plasmon resonance based fiber optic trichloroacetic acid sensor utilizing layer of silver nanoparticles and chitosan doped hydrogel

    Science.gov (United States)

    Semwal, Vivek; Shrivastav, Anand M.; Gupta, Banshi D.

    2017-02-01

    In this study, we report a silver nanoparticles/chitosan doped hydrogel-based fiber optic sensor for the detection of trichloroacetic acid (TCA). The sensor is based on the combined phenomenon of localized and propagating surface plasmons. The sensing relies on the interaction of TCA with silver nanoparticles (AgNP) which results in the electron transfer between the negative group of TCA and positive amino group of AgNP stabilizer (chitosan). This alters the mechanical properties/refractive index of the AgNP embedded hydrogel matrix as well as the refractive index of the AgNP. The change in refractive index of both in turn changes the effective refractive index of the nanocomposite hydrogel layer which can be determined using the Maxwell-Garnet Theory. Four stage optimization of the probe fabrication parameters is performed to obtain the best performance of the sensing probe. The sensor operates in the TCA concentration range 0-120 μm which is harmful for the humans and environment. The shift in peak extinction wavelength observed for the same TCA concentration range is 42 nm. The sensor has the linearity range for the TCA concentration range of 40-100 μm. The sensor possesses high sensitivity, selectivity and numerous other advantages such as ease of handling, quick response, modest cost and capability of online monitoring and remote sensing.

  12. Enhanced selectivity of boron doped diamond electrodes for the detection of dopamine and ascorbic acid by increasing the film thickness

    Energy Technology Data Exchange (ETDEWEB)

    Qi, Yao; Long, Hangyu [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Ma, Li, E-mail: marycsupm@csu.edu.cn [State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Wei, Quiping, E-mail: qiupwei@csu.edu.cn [School of Material Science and Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Li, Site [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Yu, Zhiming [School of Material Science and Engineering, Central South University, Changsha 410083 (China); State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083 (China); Hu, Jingyuan [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Liu, Peizhi [Key laboratory of interface science and engineering in advanced materials, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024,PR China (China); Wang, Yijia [School of Material Science and Engineering, Central South University, Changsha 410083 (China); Meng, Lingcong [Department of Chemistry, University of Warwick, Coventry, West Midlands CV4 7AL (United Kingdom)

    2016-12-30

    Highlights: • BDD electrodes with different thickness have been fabricated. • BDD electrodes are used for simultaneous detection of DA and AA. • Anodic pretreatment enhance the separation of DA and AA oxidation peak potential. • Thicker BDD electrode show better performance for DA detection coexisting with AA. - Abstract: In this paper, boron doped diamond (BDD) with different thickness were prepared by hot filament chemical vapor deposition. The performance of BDD electrodes for detecting dopamine (DA) and ascorbic acid (AA) were investigated. Scanning electron microscopy and Raman spectra reveal the grain size increases and the film quality improves with the increase of film thickness. Electrochemical test show that the transfer coefficient in [Fe{sub 3} (CN) {sub 6}]{sup 3−/4−} redox system increases with the increase of the film thickness. The results of selectivity and sensitivity for DA mixed with AA detection show that 8h-BDD and 12h-BDD electrodes possess well selective separated oxidation peaks of DA and AA, and the 12h-BDD electrode exhibits optimal sensitivity until the DA concentration drops to 1 μ M.

  13. Fabrication of Nitrogen-Doped Mesoporous-Carbon-Coated Palladium Nanoparticles: An Intriguing Electrocatalyst for Methanol and Formic Acid Oxidation.

    Science.gov (United States)

    Ray, Chaiti; Dutta, Soumen; Sahoo, Ramkrishna; Roy, Anindita; Negishi, Yuichi; Pal, Tarasankar

    2016-05-20

    Inspired by the attractive catalytic properties of palladium and the inert nature of carbon supports in catalysis, a concise and simple methodology for in situ nitrogen-doped mesoporous-carbon-supported palladium nanoparticles (Pd/N-C) has been developed by carbonizing a palladium dimethylglyoximate complex. The as-synthesized Pd/N-C has been exfoliated as a fuel cell catalyst by studying the electro-oxidation of methanol and formic acid. The material synthesized at 400 °C,namely, Pd/N-C-400,exhibitssuperior mass activity and stability among catalysts synthesized under different carbonization temperaturesbetween300 and 500 °C. The unique 1D porous structure in Pd/N-C-400 helps better electron transport at the electrode surface, which eventually leads to about five times better catalytic activity and about two times higher stability than that of commercial Pd/C. Thus, our designed sacrificial metal-organic templatedirected pathway becomes a promising technique for Pd/N-C synthesis with superior catalytic performances. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Dehydrogenation of Formic Acid at Room Temperature: Boosting Palladium Nanoparticle Efficiency by Coupling with Pyridinic-Nitrogen-Doped Carbon.

    Science.gov (United States)

    Bi, Qing-Yuan; Lin, Jian-Dong; Liu, Yong-Mei; He, He-Yong; Huang, Fu-Qiang; Cao, Yong

    2016-09-19

    The use of formic acid (FA) to produce molecular H2 is a promising means of efficient energy storage in a fuel-cell-based hydrogen economy. To date, there has been a lack of heterogeneous catalyst systems that are sufficiently active, selective, and stable for clean H2 production by FA decomposition at room temperature. For the first time, we report that flexible pyridinic-N-doped carbon hybrids as support materials can significantly boost the efficiency of palladium nanoparticle for H2 generation; this is due to prominent surface electronic modulation. Under mild conditions, the optimized engineered Pd/CN0.25 catalyst exhibited high performance in both FA dehydrogenation (achieving almost full conversion, and a turnover frequency of 5530 h(-1) at 25 °C) and the reversible process of CO2 hydrogenation into FA. This system can lead to a full carbon-neutral energy cycle. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Thermal stability and surface acidity of mesoporous silica doubly doped by incorporation of sulfate and zirconium ions

    Energy Technology Data Exchange (ETDEWEB)

    Salas, P. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D.F. (Mexico)]. E-mail: psalas@imp.mx; Chen, L.F. [Departamento de Ingenieria Quimica, Universidad Autonoma Metropolitana-A, Av. San Pablo 180, Col. Reynosa-Tamaulipas, 02200 Mexico D.F. (Mexico); Wang, J.A. [Laboratorio de Catalisis y Materiales, ESIQIE, Instituto Politecnico Nacional, Col. Zacatenco, 07738 Mexico D.F. (Mexico); Armendariz, H. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D.F. (Mexico); Guzman, M.L. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D.F. (Mexico); Montoya, J.A. [Instituto Mexicano del Petroleo, Programa de Ingenieria Molecular, Eje Central Lazaro Cardenas No. 152, 07730 Mexico D.F. (Mexico); Acosta, D.R. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, A. P. 20-364, 01000 Mexico D.F. (Mexico)

    2005-11-15

    A sulfated Si-Zr-MCM-41 solid with highly ordered mesostructure was synthesized through a templated synthesis route where the CTAB surfactant was used as template. During the synthesis procedure, various amounts of (NH{sub 4}){sub 2}SO{sub 4} were added into the mixed solution of Zr and Si precursors to in situ sulfate the MCM-41 solids, aiming to enhance the acidity and thermal stability. The resultant materials showed a long-range ordered hexagonal arrangement with high surface area larger than 797 m{sup 2}/g and an average pore size distributed at approximate 2.5-2.8 nm. The high-resolution TEM observations confirmed that the order of the mesostructure gained when the molar ratio of SO{sub 4} {sup 2-}/(ZrO{sub 2} + SiO{sub 2}) increased from 0.1 to 0.3 but decreased as it reached 0.5, which is consistent with the results of {sup 29}Si MAS-NMR and XRD analysis. Compared to Si-MCM-41, the (Q{sup 2} + Q{sup 3})/Q{sup 4} ratio derived from the NMR spectra of the Zr-doped sample was higher, indicating that zirconium atoms were incorporated into the silica framework. Unexpectedly, in situ sulfation does not enhance the surface Broensted acidity, most likely due to the sulfur retained within the bulk of the materials; however, it indeed improved the thermal stability of the solid and long-range order of the structure.

  16. Periodic DFT study of acidic trace atmospheric gas molecule adsorption on Ca and Fe doped MgO (001) surface basic sites

    Science.gov (United States)

    Hatch, Courtney; Orlando, Roberto

    2012-01-01

    The electronic properties of undoped and Ca or Fe doped MgO (001) surfaces, as well as their propensity towards atmospheric acidic gas (CO2, SO2 and NO2) uptake was investigated with an emphasis on gas adsorption on the basic MgO oxygen surface sites, Osurf, using periodic Density Functional Theory (DFT) calculations. Adsorption energy calculations show that MgO doping will provide stronger interactions of the adsorbate with the Osurf sites than the undoped MgO for a given adsorbate molecule. Charge transfer from the iron atom in Fe doped MgO (001) to NO2 was shown to increase the binding interaction between adsorbate by an order of magnitude, when compared to that of undoped and Ca doped MgO (001) surfaces. Secondary binding interactions of adsorbate oxygen atoms were observed with surface magnesium sites at distances close to those of the Mg-O bond within the crystal. These interactions may serve as a preliminary step for adsorption and facilitate further adsorbate transformations into other binding configurations. Impacts on global atmospheric chemistry are discussed as these adsorption phenomena can affect atmospheric gas budgets via altered partitioning and retention on mineral aerosol surfaces. PMID:22775293

  17. Hydroxyethyl cellulose doped with copper(II) phthalocyanine-tetrasulfonic acid tetrasodium salt as an effective dual functional hole-blocking layer for polymer light-emitting diodes

    Science.gov (United States)

    Wu, Cheng-Liang; Chen, Yun

    2017-07-01

    We report a doping method to improve the performance of solution-processed polymer light-emitting diodes (PLEDs). Doping 12 wt% copper(II) phthalocyanine-tetrasulfonated acid tetrasodium salt (TS-CuPc) into hydroxyethyl cellulose (HEC) as a dual functional hole-blocking layer (df-HBL) of multilayer PLED (glass/ITO/PEDOT:PSS/HY-PPV/TS-CuPc-doped HEC/LiF/Al) significantly enhanced maximum luminance, maximum current and power efficiency over that without the df-HBL (10,319 cd/m2, 2.98 cd/A and 1.24 lm/W) to (29,205 cd/m2, 13.27 cd/A and 9.56 lm/W). CV measurements reveal that HEC possesses a powerful hole-blocking capability. Topography and conductivity AFM images show that doping TS-CuPc increases the interfacial contact area and interfacial conductivity, which can overcome the insulating nature of HEC and thus further facilitate electron injection. Enhancements in device performance are attributed to the improved carrier balance and recombination in the presence of df-HBL, confirmed in electron-only and hole-only devices. Moreover, apparently raised open-circuit voltages provide further evidence that enhanced electron injection is indeed realized by the df-HBL. This study demonstrates an effective approach to develop highly efficient PLEDs.

  18. Synthesis of cobalt doped titania nano material assisted by gemini surfactant: Characterization and application in degradation of Acid Red under visible light irradiation

    Directory of Open Access Journals (Sweden)

    Radha Devi Chekuri

    2017-12-01

    Full Text Available The present work focuses on the synthesis of cobalt doped titania nano material assisted by 1,4-butane sultone anionic gemini surfactant: Co2+-TiO2 (with surfactant. The synthesized nano catalysts were characterized by XRD, UV–Vis DRS, XPS, SEM, FT-IR, HR-TEM and BET-surface area analysis. XRD and UV-DRS studies have indicated that all the catalysts synthesized were in anatase phase and red shift was observed with decrease in the band gap energy. XPS analysis of the catalysts has confirmed the presence of cobalt along with TiO2. SEM analysis indicated change in morphology of the particles without any agglomeration. From FTIR studies frequency shift was observed for TiO2 which was due to doping of cobalt into TiO2 lattice. TEM images have shown reduced particle size of Co2+-TiO2 (with surfactant. BET analysis confirmed increase in surface area of the catalyst. From BET analysis Pore volume and pore size was also analyzed. These results emphasize the important role played by the gemini surfactant on the structure and photocatalytic activity of the catalyst synthesized. The photocatalytic efficiency of the synthesized catalyst was investigated by degradation of Acid Red where degradation was completed within 30 min. Keywords: Cobalt doped titania nanomaterial, Gemini surfactant, Sol–gel method, Photocatalysis, Acid Red

  19. Photocatalytic activity of undoped and Ag-doped TiO{sub 2}-supported zeolite for humic acid degradation and mineralization

    Energy Technology Data Exchange (ETDEWEB)

    Lazau, C. [National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara, Condensed Matter Department, P. Andronescu no.1, 300254 Timisoara (Romania); Ratiu, C. [National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara, Condensed Matter Department, P. Andronescu no.1, 300254 Timisoara (Romania); National Institute for Research and Development in Microtechnologies, Erou Iancu Nicolae Street, 077190 Bucharest (Romania); Orha, C. [National Institute for Research and Development in Electrochemistry and Condensed Matter, Timisoara, Condensed Matter Department, P. Andronescu no.1, 300254 Timisoara (Romania); Pode, R. [' Politehnica' University of Timisoara, P-ta Victoriei no.2, 300006 Timisoara (Romania); Manea, F., E-mail: florica.manea@chim.upt.ro [' Politehnica' University of Timisoara, P-ta Victoriei no.2, 300006 Timisoara (Romania)

    2011-11-15

    Highlights: {yields} Hybrid materials based on natural zeolite and TiO{sub 2} obtained by solid-state reaction. {yields} XRD proved the presence of anatase form of undoped and Ag-doped TiO{sub 2} onto zeolite. {yields} FT-IR spectra evidenced the presence on TiO{sub 2} bounded at the zeolite network. {yields} Ag-doped TiO{sub 2} onto zeolitic matrix exhibited an enhanced photocatalytic activity. -- Abstract: The hybrid materials based on natural zeolite and undoped and Ag-doped TiO{sub 2}, i.e., Z-Na-TiO{sub 2} and Z-Na-TiO{sub 2}-Ag, were successfully synthesized by solid-state reaction in microwave-assisted hydrothermal conditions. Undoped TiO{sub 2} and Ag-doped TiO{sub 2} nanocrystals were previously synthesized by sol-gel method. The surface characterization of undoped TiO{sub 2}/Ag-doped TiO{sub 2} and natural zeolite hybrid materials has been investigated by X-ray diffraction, DRUV-VIS spectroscopy, FT-IR spectroscopy, BET analysis, SEM microscopy and EDX analysis. The results indicated that anatase TiO{sub 2} is the dominant crystalline type as spherical form onto zeolitic matrix. The presence of Ag into Z-Na-TiO{sub 2}-Ag was confirmed by EDX analysis. The DRUV-VIS spectra showed that Z-Na-TiO{sub 2}-Ag exhibited absorption within the range of 400-500 nm in comparison with Z-Na-TiO{sub 2} catalyst. The enhanced photocatalytic activity of Z-Na-TiO{sub 2}-Ag catalyst is proved through the degradation and mineralization of humic acid under ultraviolet and visible irradiation.

  20. Poly (vinylidene fluoride-co-hexafluoropropylene)/polybenzimidazole blend nanofiber supported Nafion membranes for direct methanol fuel cells

    Science.gov (United States)

    Wang, Shih-Hua; Lin, Hsiu-Li

    2014-07-01

    This article presents preparation of poly (vinylidene fluoride-co-hexafluoropropylene) (PVdF-co-HFP) and polybenzimidazole (PBI) blend electrospun nanofiber (PVFP-BI) films from N,N‧-dimethyl acetamide (DMAc)/acetone mixture solutions. Using the PVFP-BI nanofiber film (thickness ∼13-15 μm) as a supporting material for impregnating Nafion resin solution, Nafion/PVFP-BI composite membranes (thickness ∼50 μm) are prepared and direct methanol fuel cell (DMFC) tests are performed. Better DMFC performance of the Nafion/PVFP-BI composite membrane than the commercial Nafion-117 (thickness ∼175 μm) and Nafion-212 (thickness ∼50 μm) membranes when blending with 5-10 wt.% of PBI in the PVFP-BI nanofiber support film is demonstrated.

  1. Nitrogen-doped carbon quantum dots as a fluorescence probe combined with magnetic solid-phase extraction purification for analysis of folic acid in human serum.

    Science.gov (United States)

    Wang, Meng; Jiao, Yang; Cheng, Chunsheng; Hua, Jianhao; Yang, Yaling

    2017-12-01

    A novel and sensitive method based on nitrogen-doped carbon quantum dots as a fluorescence probe coupled with magnetic solid-phase extraction (MSPE) purification for analysis of folic acid (FA) in human serum samples has been established for the first time. In the developed system, magnetic nanoparticles coated with hexanoic acid (Fe3O4@C6) were synthesized by a one-step chemical co-precipitation method with good magnetic properties and dispersibility for sample purification, and it is better to be separated from the sample. High fluorescence nitrogen-doped carbon quantum dots (N-CQDs), simply prepared using a one-step hydrothermal method with nitrilotriacetic acid, could be selectively quenched by FA. Based on this phenomenon, a fluorescence assay was proposed for specific determination of FA. Various operational experiment parameters have been studied and optimized in detail. Under the optimum experimental conditions, the detection limit of the proposed method for FA was evaluated to be 0.5 nM (S/N = 3), while the relative standard deviation (RSD) was 1.2% (n = 6). Finally, the proposed method was applied for determination of trace levels of FA from human serum samples and quantitative recoveries were achieved within the range of 95.7-103.5%. All of the results showed that the proposed method had significant application in further research. Graphical abstract Schematic of synthesis of N-CQDs and schematic of suggested mode for analysis of folic acid (FA).

  2. Silica-titania xerogel doped with Mo,P-heteropoly compounds for solid phase spectrophotometric determination of ascorbic acid in fruit juices, pharmaceuticals, and synthetic urine.

    Science.gov (United States)

    Morosanova, Maria A; Morosanova, Elena I

    2017-01-01

    Ascorbic acid is one of the most important vitamins to monitor in dietary sources (juices and vitamins) and biological liquids. Silica and silica-titania xerogels doped with Mo,P-heteropoly compounds (HPC) have been synthesized varying titanium(IV) and HPC content in sol. Their surface area and porosity have been studied with nitrogen adsorption and scanning electron microscopy, their elemental composition has been studied with energy-dispersive X-ray analysis. The redox properties of the sensor material with sufficient porosity and maximal HPC content have been studied with potentiometry and solid phase spectrophotometry and it has been used for solid phase spectrophotometric determination of ascorbic acid. The proposed method is characterized by good selectivity, simple probe pretreatment and broad analytical range (2-200 mg/L, LOD 0.7 mg/L) and has been applied to the analysis of fruit juices, vitamin tablets, and synthetic urine. New sensor material has been used for simple and selective solid phase spectrophotometric procedure of ascorbic acid determination in fruit juices, vitamin tablets, and synthetic urine.Graphical abstractWe synthesized several silica-titania xerogels doped with Mo,P-heteropoly compounds, studied their properties, and designed the sensor material for solid phase spectrophotometric determination of ascorbic acid in fruit juices, pharmaceuticals, and synthetic urine.

  3. Photoluminescence and lasing from deoxyribonucleic acid (DNA) thin films doped with sulforhodamine

    Science.gov (United States)

    Yu, Z.; Li, W.; Hagen, J. A.; Zhou, Y.; Klotzkin, D.; Grote, J. G.; Steckl, A. J.

    2007-03-01

    Thin solid films of salmon deoxyribonucleic acid (DNA) have been fabricated by treatment with a surfactant and used as host for the laser dye sulforhodamine (SRh). The DNA films have an absorption peak at ˜260 nm owing to absorption by the nitrogenous aromatic bases. The SRh molecules in the DNA films have absorption and emission peaks at 578 and 602 nm, respectively. The maximum emission was obtained at ˜1 wt. % SRh in DNA, equivalent to ˜100 DNA base pairs per SRh molecule. A distributed feedback grating structure was fabricated on a SiO2-Si substrate using interference lithography. The grating period of 437 nm was selected, corresponding to second-order emission at the amplified spontaneous emission wavelength of 650 nm. Lasing was obtained by pumping with a doubled Nd:YAG laser at 532 nm. The lasing threshold was 3 μJ, corresponding to ˜30 μJ/cm2 or 4 kW/cm2. The emission linewidth decreased from ˜30 nm in the amplified spontaneous emission mode to <0.4 nm (instrument limited) in the lasing mode. The slope efficiency of the lasing was ˜1.2%.

  4. Au/ZnO hybrid nanocatalysts impregnated in N-doped graphene for simultaneous determination of ascorbic acid, acetaminophen and dopamine

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Xianlan [School of Science, Honghe University, Mengzi, Yunnan 661100 (China); Key Laboratory of Natural Pharmaceutical & Chemical Biology of Yunnan Province, Mengzi, Yunnan 661100 (China); Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China); Zhang, Guowei; Shi, Ling; Pan, Shanqing [School of Science, Honghe University, Mengzi, Yunnan 661100 (China); Key Laboratory of Natural Pharmaceutical & Chemical Biology of Yunnan Province, Mengzi, Yunnan 661100 (China); Liu, Wei, E-mail: liuwei4728@126.com [School of Science, Honghe University, Mengzi, Yunnan 661100 (China); Key Laboratory of Natural Pharmaceutical & Chemical Biology of Yunnan Province, Mengzi, Yunnan 661100 (China); Pan, Hiabo [Fujian Key Lab of Medical Instrument & Pharmaceutical Technology, Yishan Campus, Fuzhou University, Fuzhou, Fujian 350002 (China)

    2016-08-01

    The formation of nitrogen-doped (N-doped) graphene uses hydrothermal method with urea as reducing agent and nitrogen source. The surface elemental composition of the catalyst was analyzed through XPS, which showed a high content of a total N species (7.12 at.%), indicative of the effective N-doping, present in the form of pyridinic N, pyrrolic N and graphitic N groups. Moreover, Au nanoparticles deposited on ZnO nanocrystals surface, forming Au/ZnO hybrid nanocatalysts, undergo a super-hydrophobic to super-hydrophilic conversion. Herein, we present Au/ZnO hybrid nanocatalysts impregnated in N-doped graphene sheets through sonication technique of the Au/ZnO/N-doped graphene hybrid nanostructures. The as-prepared Au/ZnO/N-doped graphene hybrid nanostructure modified glassy carbon electrode (Au/ZnO/N-doped graphene/GCE) was first employed for the simultaneous determination of ascorbic acid (AA), dopamine (DA) and acetaminophen (AC). The oxidation over-potentials of AA, DA and AC decreased dramatically, and their oxidation peak currents increased significantly at Au/ZnO/N-doped graphene/GCE compared to those obtained at the N-doped graphene/GCE and bare CCE. The peak separations between AA and DA, DA and AC, and AC and AA are large up to 195, 198 and 393 mV, respectively. The calibration curves for AA, DA and AC were obtained in the range of 30.00–13.00 × 10{sup 3}, 2.00–0.18 × 10{sup 3} and 5.00–3.10 × 10{sup 3} μM, respectively. The detection limits (S/N = 3) were 5.00, 0.40 and 0.80 μM for AA, DA and AC, respectively. - Graphical abstract: A novel Au/ZnO/N-doped graphene hybrid nanostructure was synthesized for the electrochemical evaluation of AA, DA and AC. The formation of N-doped graphene uses hydrothermal method with urea as reducing agent and nitrogen source. Moreover, Au nanoparticles deposited on ZnO nanocrystals surface, forming Au/ZnO hybrid nanocatalysts, undergo a super-hydrophobic to superhydrophilic conversion. We present Au/ZnO hybrid

  5. Interaction of Phosphoric Acid with Cell Components in High Temperature Polymer Electrolyte Fuel Cells

    OpenAIRE

    Liu, Fang

    2014-01-01

    A high-temperature polymer electrolyte fuel cell (HT-PEFC) is an efficient and clean energy convertingdevice. The protonic conductivity of the electrodes and the polybenzimidazole-type membraneis assured by phosphoric acid. The electrochemical reactions in HT-PEFCs of hydrogen andoxygen to water take place in the electrodes of the membrane electrode assembly (MEA) whichare partly soaked with phosphoric acid. The performance of a HT-PEFC depends mainly on theinteractions between all cell compo...

  6. Molecular dynamics investigation of separation of hydrogen sulfide from acidic gas mixtures inside metal-doped graphite micropores.

    Science.gov (United States)

    Huang, Pei-Hsing

    2015-09-21

    The separation of poisonous compounds from various process fluids has long been highly intractable, motivating the present study on the dynamic separation of H2S in acidic-gas-mixture-filled micropores. The molecular dynamics approach, coupled with the isothermal-isochoric ensemble, was used to model the molecular interactions and adsorption of H2S/CO2/CO/H2O mixtures inside metal-doped graphite slits. Due to the difference in the adsorption characteristics between the two distinct adsorbent materials, the metal dopant in the graphitic micropores leads to competitive adsorption, i.e. the Au and graphite walls compete to capture free adsorbates. The effects of competitive adsorption, coupled with changes in the gas temperature, concentration, constituent ratio and slit width on the constituent separation of mixtures were systematically studied. The molecule-wall binding energies calculated in this work (those of H2S, H2O and CO on Au walls and those of H2O, CO and CO2 on graphite walls) show good agreement with those obtained using density functional theory (DFT) and experimental results. The z-directional self-diffusivities (Dz) for adsorbates inside the slit ranged from 10(-9) to 10(-7) m(2) s(-1) as the temperature was increased from 10 to 500 K. The values are comparable with those for a typical microporous fluid (10(-8)-10(-9) m(2) s(-1) in a condensed phase and 10(-6)-10(-7) m(2) s(-1) in the gaseous state). The formation of H-bonding networks and hydrates of H2S is disadvantageous for the separation of mixtures. The results indicate that H2S can be efficiently separated from acidic gas mixtures onto the Au(111) surface by (i) reducing the mole fraction of H2S and H2O in the mixtures, (ii) raising the gas temperature to the high temperature limit (≥400 K), and (iii) lowering the slit width to below the threshold dimension (≤23.26 Å).

  7. Complete doping in solid-state by silica-supported perchloric acid as dopant solid acid: Synthesis and characterization of the novel chiral composite of poly [(±)-2-(sec-butyl) aniline

    Energy Technology Data Exchange (ETDEWEB)

    Farrokhzadeh, Abdolkarim; Modarresi-Alam, Ali Reza, E-mail: modaresi@chem.usb.ac.ir

    2016-05-15

    Poly [(±)-2-(sec-butyl) aniline]/silica-supported perchloric acid composites were synthesized by combination of poly[(±)-2-sec-butylaniline] base (PSBA) and the silica-supported perchloric acid (SSPA) as dopant solid acid in solid-state. The X-ray photoelectron spectroscopy (XPS) and CHNS results confirm nigraniline oxidation state and complete doping for composites (about 75%) and non-complete for the PSBA·HCl salt (about 49%). The conductivity of samples was (≈0.07 S/cm) in agreement with the percent of doping obtained of the XPS analysis. Also, contact resistance was determined by circular-TLM measurement. The morphology of samples by the scanning electron microscopy (SEM) and their coating were investigated by XPS, SEM-map and energy-dispersive X-ray spectroscopy (EDX). The key benefits of this work are the preparation of conductive chiral composite with the delocalized polaron structure under green chemistry and solid-state condition, the improvement of the processability by inclusion of the 2-sec-butyl group and the use of dopant solid acid (SSPA) as dopant. - Highlights: • The solid-state synthesis of the novel chiral composites of poly[(±)-2-(sec-butyl)aniline] (PSBA) and silica-supported perchloric acid (SSPA). • It takes 120 h for complete deprotonation of PSBA.HCl salt. • Use of SSPA as dopant solid acid for the first time to attain the complete doping of PSBA. • The coating of silica surface with PSBA.

  8. Structural and transport effects of doping perfluorosulfonic acid polymers with the heteropoly acids, H{sub 3}PW{sub 12}O{sub 40} or H{sub 4}SiW{sub 12}O{sub 40}

    Energy Technology Data Exchange (ETDEWEB)

    Meng Fanqin [Department of Chemical Engineering, Colorado School of Mines, Golden, CO 80401 (United States); Aieta, Niccolo V. [Department of Chemical Engineering, Colorado School of Mines, Golden, CO 80401 (United States); Hydrogen and Electricity, Systems and Infrastructure Group, National Renewable Energy Laboratory, Golden, CO 80401 (United States); Dec, Steven F. [Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401 (United States); Horan, James L. [Department of Chemistry and Geochemistry, Colorado School of Mines, Golden, CO 80401 (United States); Hydrogen and Electricity, Systems and Infrastructure Group, National Renewable Energy Laboratory, Golden, CO 80401 (United States); Williamson, Don [Department of Physics, Colorado School of Mines, Golden, CO 80401 (United States); Frey, Matthew H. [3M Corporate Research Materials Laboratory, 3M Company, St. Paul, MN 55144 (United States); Pham, Phat [3M Fuel Cell Components Program, 3M Company, St. Paul, MN 55144 (United States); Turner, John A. [Hydrogen and Electricity, Systems and Infrastructure Group, National Renewable Energy Laboratory, Golden, CO 80401 (United States); Yandrasits, Michael A.; Hamrock, Steven J. [3M Fuel Cell Components Program, 3M Company, St. Paul, MN 55144 (United States); Herring, Andrew M. [Department of Chemical Engineering, Colorado School of Mines, Golden, CO 80401 (United States)], E-mail: aherring@mines.edu

    2007-12-20

    A perfluorosulfonic acid (PFSA) polymer with pendant side chain -O(CF{sub 2}){sub 4}SO{sub 3}H was doped with the heteropoly acids (HPAs), H{sub 3}PW{sub 12}O{sub 40} and H{sub 4}SiW{sub 12}O{sub 40}. Infrared spectroscopy revealed a strong interaction between the HPA and the PFSA ionomer. Modes associated with the peripheral bonds of the HPA were shifted to lower wave numbers when doped into PFSA membranes. Small-angle X-ray scattering (SAXS) measurements showed the presence of large crystallites of HPA in the membrane with d spacings of ca. 10 A, close to the lattice spacing observed in bulk HPA crystals. Under wet conditions the HPA was more dispersed and constrained the size of the sulfonic acid clusters to 20 A at a 5 wt% HPA doping level, the same as in the vacuum treated ionomer samples. Under conditions of minimum hydration the HPA decreased the E{sub a} for the self-diffusion of water from 27 to 15 kJ mol{sup -1}. The reverse trend was seen under 100% RH conditions. Proton conductivity measurements showed improved proton conductivity of the HPA doped PFSAs at a constant dew point of 80 deg. C for all temperatures up to 120 deg. C and at all relative hummidities up to 80%. The activation energy for proton conduction generally was lower than for the undoped materials at RH {<=}80%. Significantly the E{sub a} was 1/2 that of the undoped material at RHs of 40 and 60%. A practical proton conductivity of 113 mS cm{sup -1} was observed at 100 deg. C and 80% RH.

  9. Pure and Fe-Doped Mesoporous Titania Catalyse the Oxidation of Acid Orange 7 by H2O2 under Different Illumination Conditions: Fe Doping Improves Photocatalytic Activity under Simulated Solar Light

    Directory of Open Access Journals (Sweden)

    Francesca S. Freyria

    2017-07-01

    Full Text Available A sample of mesoporous TiO2 (MT, specific surface area = 150 m2·g−1 and two samples of MT containing 2.5 wt.% Fe were prepared by either direct synthesis doping (Fe2.5-MTd or impregnation (Fe2.5-MTi. Commercial TiO2 (Degussa P25, specific surface area = 56 m2 g−1 was used both as a benchmark and as a support for impregnation with either 0.8 or 2.5 wt.% Fe (Fe0.80-IT and Fe2.5-IT. The powders were characterized by X-ray diffraction, N2 isotherms at −196 °C, Energy Dispersive X-ray (EDX Spectroscopy, X-ray Photoelectron Spectroscopy (XPS, Diffuse Reflectance (DR ultra-violet (UV-Vis and Mössbauer spectroscopies. Degradation of Acid Orange 7 (AO7 by H2O2 was the test reaction: effects of dark-conditions versus both UV and simulated solar light irradiation were considered. In dark conditions, AO7 conversion was higher with MT than with Degussa P25, whereas Fe-containing samples were active in a (slow Fenton-like reaction. Under UV light, MT was as active as Degussa P25, and Fe doping enhanced the photocatalytic activity of Fe2.5-MTd; Fe-impregnated samples were also active, likely due to the occurrence of a photo-Fenton process. Interestingly, the Fe2.5-MTd sample showed the best performance under solar light, confirming the positive effect of Fe doping by direct synthesis with respect to impregnation.

  10. Layered Lithium-Rich Oxide Nanoparticles Doped with Spinel Phase: Acidic Sucrose-Assistant Synthesis and Excellent Performance as Cathode of Lithium Ion Battery.

    Science.gov (United States)

    Chen, Min; Chen, Dongrui; Liao, Youhao; Zhong, Xiaoxin; Li, Weishan; Zhang, Yuegang

    2016-02-01

    Nanolayered lithium-rich oxide doped with spinel phase is synthesized by acidic sucrose-assistant sol-gel combustion and evaluated as the cathode of a high-energy-density lithium ion battery. Physical characterizations indicate that the as-synthesized oxide (LR-SN) is composed of uniform and separated nanoparticles of about 200 nm, which are doped with about 7% spinel phase, compared to the large aggregated ones of the product (LR) synthesized under the same condition but without any assistance. Charge/discharge demonstrates that LR-SN exhibits excellent rate capability and cyclic stability: delivering an average discharge capacity of 246 mAh g(-1) at 0.2 C (1C = 250 mA g(-1)) and earning a capacity retention of 92% after 100 cycles at 4 C in the lithium anode-based half cell, compared to the 227 mA g(-1) and the 63% of LR, respectively. Even in the graphite anode-based full cell, LR-SN still delivers a capacity of as high as 253 mAh g(-1) at 0.1 C, corresponding to a specific energy density of 801 Wh kg(-1), which are the best among those that have been reported in the literature. The separated nanoparticles of the LR-SN provide large sites for charge transfer, while the spinel phase doped in the nanoparticles facilitates lithium ion diffusion and maintains the stability of the layered structure during cycling.

  11. Effects of the sintering temperature on the flux-pinning mechanism and the activation energy of malic-acid doped MgB2

    Directory of Open Access Journals (Sweden)

    J Peleckis

    2012-12-01

    Full Text Available   The flux-pinning mechanism and activation energy of 10 wt % malic acid-doped MgB2 were investigated by measuring of the critical current density and resistivity as a function of magnetic field and temperature. A crossover field, Bsb, was observed from the single vortex to the small vortex bundle pinning regime. For the sintered sample, the temperature dependence of Bsb(T at low temperature is in good agreement with the δℓ pinning mechanism, i.e., pinning associated with charge-carrier mean free path fluctuation. The activation energy was decreased by increasing the magnetic field and increased by increasing sintering temperature.

  12. Fouling behaviors of polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes for engineering osmosis processes

    KAUST Repository

    Chen, Sicong

    2014-02-01

    This paper investigated the individual effects of reverse salt flux and permeate flux on fouling behaviors of as-spun and annealed polybenzimidazole (PBI)-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) hollow fiber membranes under forward osmosis (FO) and pressure retarded osmosis (PRO) processes. Two types of membrane fouling had been studied; namely, inorganic fouling (CaSO4·2H2O gypsum scaling) during FO operations and organic fouling (sodium alginate fouling) during PRO operations. It is found that gypsum scaling on the membrane surface may be inhibited and even eliminated with an increase in reverse MgCl2 flux due to competitive formations of MgSO4° and CaSO4·2H2O. In contrast, the increase of reverse NaCl flux exhibits a slight enhancement on alginate fouling in both FO and PRO processes. Comparing to the reverse salt flux, the permeate flux always plays a dominant role in fouling. Therefore, lesser fouling has been observed on the membrane surface under the pressurized PRO process than FO process because the reduced initial flux mitigates the fouling phenomena more significantly than the enhancement caused by an increase in reverse NaCl flux. © 2013 Elsevier B.V.

  13. Gypsum (CaSO42H2O) scaling on polybenzimidazole and cellulose acetate hollow fiber membranes under forward osmosis

    KAUST Repository

    Chen, Si Cong

    2013-11-08

    We have examined the gypsum (CaSO42H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42 14.85 after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface. 2013 by the authors; licensee MDPI, Basel, Switzerland.

  14. The neural networks based modeling of a polybenzimidazole-based polymer electrolyte membrane fuel cell: Effect of temperature

    Science.gov (United States)

    Lobato, Justo; Cañizares, Pablo; Rodrigo, Manuel A.; Linares, José J.; Piuleac, Ciprian-George; Curteanu, Silvia

    Neural network models represent an important tool of Artificial Intelligence for fuel cell researchers in order to help them to elucidate the processes within the cells, by allowing optimization of materials, cells, stacks, and systems and support control systems. In this work three types of neural networks, that have as common characteristic the supervised learning control (Multilayer Perceptron, Generalized Feedforward Network and Jordan and Elman Network), have been designed to model the performance of a polybenzimidazole-polymer electrolyte membrane fuel cells operating upon a temperature range of 100-175 °C. The influence of temperature of two periods was studied: the temperature in the conditioning period and temperature when the fuel cell was operating. Three inputs variables: the conditioning temperature, the operating temperature and current density were taken into account in order to evaluate their influence upon the potential, the cathode resistance and the ohmic resistance. The Multilayer Perceptron model provides good predictions for different values of operating temperatures and potential and, hence, it is the best choice among the study models, recommended to investigate the influence of process variables of PEMFCs.

  15. Nitrogen-Doped Nanoporous Carbon Membranes with Co/CoP Janus-Type Nanocrystals as Hydrogen Evolution Electrode in Both Acidic and Alkaline Environments

    KAUST Repository

    Wang, Hong

    2017-03-31

    Self-supported electrocatalysts being generated and employed directly as electrodes for energy conversion has been intensively pursued in the fields of materials chemistry and energy. Herein, we report a synthetic strategy to prepare freestanding hierarchically structured, nitrogen-doped nanoporous graphitic carbon membranes functionalized with Janus-type Co/CoP nanocrystals (termed as HNDCM-Co/CoP), which were successfully applied as a highly efficient, binder-free electrode in the hydrogen evolution reaction (HER). Benefited from multiple structural merits, such as a high degree of graphitization, three-dimensionally interconnected micro/meso/macropores, uniform nitrogen doping, well-dispersed Co/CoP nanocrystals, as well as the confinement effect of the thin carbon layer on the nanocrystals, HNDCM-Co/CoP exhibited superior electrocatalytic activity and long-term operation stability for HER under both acidic and alkaline conditions. As a proof-of-concept of practical usage, a 5.6 cm × 4 cm × 60 μm macroscopic piece of HNDCM-Co/CoP was prepared in our laboratory. Driven by a solar cell, electroreduction of water in alkaline conditions (pH 14) was performed, and H was produced at a rate of 16 mL/min, demonstrating its potential as real-life energy conversion systems.

  16. Increasing the Fill Factor of Inverted P3HT:PCBM Solar Cells Through Surface Modification of Al-Doped ZnO via Phosphonic Acid-Anchored C60 SAMs

    DEFF Research Database (Denmark)

    Stubhan, Tobias; Salinas, Michael; Ebel, Alexander

    2012-01-01

    The influence of aluminum-doped zinc oxide (AZO) electron extraction layers modified with self-assembled monolayers (SAMs) on inverted polymer solar cells is investigated. It is found that AZO modification with phosphonic acid-anchored Fullerene–SAMs leads to a reduction of the series resistance,...

  17. Thin film thermocouples for in situ membrane electrode assembly temperature measurements in a polybenzimidazole-based high temperature proton exchange membrane unit cell

    DEFF Research Database (Denmark)

    Ali, Syed Talat; Lebæk, Jesper; Nielsen, Lars Pleth

    2010-01-01

    This paper presents Type-T thin film thermocouples (TFTCs) fabricated on Kapton (polyimide) substrate for measuring the internal temperature of PBI(polybenzimidazole)-based high temperature proton exchange membrane fuel cell (HT-PEMFC). Magnetron sputtering technique was employed to deposit a 2 mu...... m thick layer of TFTCs on 75 mu m thick Kapton foil. The Kapton foil was treated with in situ argon plasma etching to improve the adhesion between TFTCs and the Kapton substrate. The TFTCs were covered with a 7 mu m liquid Kapton layer using spin coating technique to protect them from environmental...

  18. An ultrasensitive electrochemical sensor for simultaneous determination of xanthine, hypoxanthine and uric acid based on Co doped CeO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Lavanya, N. [Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi 630003, Tamilnadu (India); Sekar, C., E-mail: Sekar2025@gmail.com [Department of Bioelectronics and Biosensors, Alagappa University, Karaikudi 630003, Tamilnadu (India); Murugan, R.; Ravi, G. [Department of Physics, Alagappa University, Karaikudi 630003, Tamilnadu (India)

    2016-08-01

    A novel electrochemical sensor has been fabricated using Co doped CeO{sub 2} nanoparticles for selective and simultaneous determination of xanthine (XA), hypoxanthine (HXA) and uric acid (UA) in a phosphate buffer solution (PBS, pH 5.0) for the first time. The Co-CeO{sub 2} NPs have been prepared by microwave irradiation method and characterized by Powder XRD, Raman spectroscopy, HRTEM and VSM measurements. The electrochemical behaviours of XA, HXA and UA at the Co-CeO{sub 2} NPs modified glassy carbon electrode (GCE) were studied by cyclic voltammetry and square wave voltammetry methods. The modified electrode exhibited remarkably well-separated anodic peaks corresponding to the oxidation of XA, HXA and UA over the concentration range of 0.1–1000, 1–600 and 1–2200 μM with detection limits of 0.096, 0.36, and 0.12 μM (S/N = 3), respectively. For simultaneous detection by synchronous change of the concentrations of XA, HXA and UA, the linear responses were in the range of 1–400 μM each with the detection limits of 0.47, 0.26, and 0.43 μM (S/N = 3), respectively. The fabricated sensor was further applied to the detection of XA, HXA and UA in human urine samples with good selectivity and high reproducibility. - Highlights: • A novel electrochemical sensor has been fabricated for simultaneous determination of purine metabolites xanthine, hypoxanthine, and uric acid based on Co doped CeO{sub 2} nanoparticles. • The Co-CeO{sub 2} modified glassy carbon electrode exhibited wide linear range towards the detection of XA, HXA and UA than ever reported in the literature. • The fabricated sensor was successfully applied for the analysis of human urine samples with satisfactory results.

  19. Flexible camphor sulfonic acid-doped PAni/α-Fe{sub 2}O{sub 3} nanocomposite films and their room temperature ammonia sensing activity

    Energy Technology Data Exchange (ETDEWEB)

    Bandgar, D.K. [Functional Materials Research Laboratory (FMRL), School of Physical Sciences, Solapur University, Solapur 413 255, M.S. (India); Navale, S.T. [College of Materials Science and Engineering, Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, Nanshan District Key Lab for Biopolymers and Safety Evaluation, Shenzhen University, Shenzhen 518060 (China); Navale, Y.H.; Ingole, S.M. [Functional Materials Research Laboratory (FMRL), School of Physical Sciences, Solapur University, Solapur 413 255, M.S. (India); Stadler, F.J. [College of Materials Science and Engineering, Shenzhen Key Laboratory of Polymer Science and Technology, Guangdong Research Center for Interfacial Engineering of Functional Materials, Nanshan District Key Lab for Biopolymers and Safety Evaluation, Shenzhen University, Shenzhen 518060 (China); Ramgir, N.; Aswal, D.K.; Gupta, S.K. [Technical Physics Division, Babha Atomic Research Centre, Mumbai, M.S. (India); Mane, R.S. [School of Physical Sciences, SRTM University, Nanded 431606 (India); Patil, V.B., E-mail: drvbpatil@gmail.com [Functional Materials Research Laboratory (FMRL), School of Physical Sciences, Solapur University, Solapur 413 255, M.S. (India)

    2017-03-01

    Composite nanostructures play a crucial role in gas sensing applications owing to their tunable properties and sizes. The main goal of this article is to prepare camphor sulfonic acid (10–50 wt%)-doped PAni/α-Fe{sub 2}O{sub 3} (PFC) composite nanostructured films on flexible polyethylene terephthalate (PET) substrate through in-situ polymerization process and study their gas sensing activity towards various gases. Structural and morphological measurements along with gas sensing properties in terms of selectivity, response, stability, and response-recovery times are investigated and reported. The gas selectivity tests of flexible PFC nanostructured composite films are performed towards different gases such as NO{sub 2}, NH{sub 3}, LPG, CH{sub 3}OH, and C{sub 2}H{sub 5}OH etc., wherein all the flexible PFC (10–50%) films demonstrate a superior selectivity towards NH{sub 3} gas even in the presence of other test gases. Among the different compositions, 30% PFC flexible film exhibits highest response of 72% to 100 ppm NH{sub 3} with good response time of 65 s. The systematic study between PFC flexible nanocomposite films and NH{sub 3} gas is conducted and reported. In addition, the interfacial charge transfer kinetics across NH{sub 3} and PFC film interface was investigated by means of impendence spectroscopy study. - Highlights: • Novel route of preparation of camphor sulfonic acid doped PAni-Fe{sub 2}O{sub 3} (PFC) flexible films. • XRD, FTIR, and RAMAN analysis confirms the formation of PFC composites. • PFC films are highly selective towards NH{sub 3} gas at room temperature. • PFC films able to detect as low as 2.5 ppm concentration of NH{sub 3} gas. • 30% PFC flexible film exhibits highest response of 72%–100 ppm NH{sub 3} gas with good response time of 65 s.

  20. Nanocrystalline semiconductor doped rare earth oxide for the photocatalytic degradation studies on Acid Blue 113: A di-azo compound under UV slurry photoreactor.

    Science.gov (United States)

    Suganya Josephine, G A; Mary Nisha, U; Meenakshi, G; Sivasamy, A

    2015-11-01

    Preventive measures for the control of environmental pollution and its remediation has received much interest in recent years due to the world-wide increase in the contamination of water bodies. Contributions of these harmful effluents are caused by the leather processing, pharmaceutical, cosmetic, textile, agricultural and other chemical industries. Nowadays, advanced oxidation processes considered to be better option for the complete destruction of organic contaminants in water and wastewater. Acid Blue 113 is a most widely used di-azo compound in leather, textile, dying and food industry as a color rending compound. In the present study, we have reported the photo catalytic degradation of Acid Blue 113 using a nanocrystalline semiconductor doped rare earth oxide as a photo catalyst under UV light irradiation. The photocatalyst was prepared by a simple precipitation technique and were characterized by XRD, FT-IR, UV-DRS and FE-SEM analysis. The experimental results proved that the prepared photo catalyst was nanocrystalline and highly active in the UV region. The UV-DRS results showed the band gap energy was 3.15eV for the prepared photo catalyst. The photodegradation efficiency was analyzed by various experimental parameters such as pH, catalyst dosage, variation of substrate concentration and effect of electrolyte addition. The photo degradation process followed a pseudo first order kinetics and was continuously monitored by UV-visible spectrophotometer. The experimental results proved the efficacy of the nanocrystalline zinc oxide doped dysprosium oxide which are highly active under UV light irradiations. It is also suggested that the prepared material would find wider applications in environmental remediation technologies to remove the carcinogenic and toxic moieties present in the industrial effluents. Copyright © 2015 Elsevier Inc. All rights reserved.

  1. Self-doped anthranilic acid-pyrrole copolymer/gold electrodes for selective preconcentration and determination of Cu(I) by differential pulse anodic stripping voltammetry.

    Science.gov (United States)

    Nateghi, M R; Fallahian, M H

    2007-05-01

    Electropolymerization of anthranilic acid/pyrrole (AA/PY) at solid substrate electrodes (platinum, gold, and glassy carbon) gave stable and water-insoluble films under a wide range of pH. Combining high conductivity of the polypyrrole (PPY) and pH independence of the electrochemical activity of the self-doped carboxylic acid-substituted polyaniline allows us to prepare an improved functionalized PPY-modified electrode to collect and measure Cu(I) species. The differential pulse stripping analysis of the copper ions using a polyanthranilic acid-co-polypyrrole (PAA/PPY)-modified electrode consisted of three steps: accumulation, electrochemical reduction to the elemental copper and stripping step. Factors affecting these steps, including electropolymerization conditions, accumulation and stripping medium, reduction potential, reduction time and accumulation time, were systematically investigated. A detection limit of 5.3 x 10(-9) M Cu(I) was achieved for a 7.0 min accumulation. For 12 determinations of Cu(I) at concentrations of 1.0 x 10(-8) M, an RSD of 3.5% was obtained. The log I(p) was found to vary linearly with log[Cu(I)] in the concentration range from 7.0 x 10(-9) to 1.0 x 10(-5) M.

  2. 40 CFR 721.9511 - Silicic acid (H6SiO2O7), magnesium, strontium salt(1:1:2), dysprosium and europium-doped.

    Science.gov (United States)

    2010-07-01

    ..., strontium salt(1:1:2), dysprosium and europium-doped. 721.9511 Section 721.9511 Protection of Environment...), magnesium, strontium salt(1:1:2), dysprosium and europium-doped. (a) Chemical substance and significant new..., strontium salt(1:1:2), dysprosium and europium-doped. (PMN P-98-848; CAS No.181828-07-9) is subject to...

  3. Airplane dopes and doping

    Science.gov (United States)

    Smith, W H

    1919-01-01

    Cellulose acetate and cellulose nitrate are the important constituents of airplane dopes in use at the present time, but planes were treated with other materials in the experimental stages of flying. The above compounds belong to the class of colloids and are of value because they produce a shrinking action on the fabric when drying out of solution, rendering it drum tight. Other colloids possessing the same property have been proposed and tried. In the first stages of the development of dope, however, shrinkage was not considered. The fabric was treated merely to render it waterproof. The first airplanes constructed were covered with cotton fabric stretched as tightly as possible over the winds, fuselage, etc., and flying was possible only in fine weather. The necessity of an airplane which would fly under all weather conditions at once became apparent. Then followed experiments with rubberized fabrics, fabrics treated with glue rendered insoluble by formaldehyde or bichromate, fabrics treated with drying and nondrying oils, shellac, casein, etc. It was found that fabrics treated as above lost their tension in damp weather, and the oil from the motor penetrated the proofing material and weakened the fabric. For the most part the film of material lacked durability. Cellulose nitrate lacquers, however were found to be more satisfactory under varying weather conditions, added less weight to the planes, and were easily applied. On the other hand, they were highly inflammable, and oil from the motor penetrated the film of cellulose nitrate, causing the tension of the fabric to be relaxed.

  4. Optical, thermal and electrical properties of polybenzimidazoles derived from substituted benzimidazoles

    Science.gov (United States)

    Anand, Siddeswaran; Muthusamy, Athianna

    2017-11-01

    Three benzimidazole monomers synthesized by condensing various substituted phenolic aldehydes with 4-methylphenylenediamine were converted in to polymers by oxidative polycondensation. The structure of the monomers and polymers were confirmed by various spectroscopic techniques. Electronic distribution of molecular frontier orbitals and optimized geometries of monomers were calculated by Gaussian 09 package. The spectral results showed that the repeating units are connected through both Csbnd C and Csbnd Osbnd C linkages. Both polymers and monomers are showing good fluorescence emission in blue region. The electrical conductivity of I2 doped PBIs was measured using two point probe technique. The conductivities of PBIs were compared on the basis of the charge densities obtained from Huckel method on imidazole nitrogen which is involved in iodine coordination. The conductivity of polymers increases with increase in iodine vapour contact time. The dielectric properties of the synthesized polymers have been investigated at different temperature and frequency. Among the PBIs, PBIOP is having greater thermal stability and is shown by high carbines residues of around 50% at 500 °C in thermogravimetric analysis.

  5. Doped Nanocrystals

    National Research Council Canada - National Science Library

    David J. Norris; Alexander L. Efros; Steven C. Erwin

    2008-01-01

    The critical role that dopants play in semiconductor devices has stimulated research on the properties and the potential applications of semiconductor nanocrystals, or colloidal quantum dots, doped...

  6. Palladium Nanoparticles Supported on Nitrogen and Sulfur Dual-Doped Graphene as Highly Active Electrocatalysts for Formic Acid and Methanol Oxidation.

    Science.gov (United States)

    Zhang, Xin; Zhu, Jixin; Tiwary, Chandra Sekhar; Ma, Zhongyuan; Huang, Huajie; Zhang, Jianfeng; Lu, Zhiyong; Huang, Wei; Wu, Yuping

    2016-05-04

    Optimized designing of highly active electrocatalysts has been regarded as a critical point to the development of portable fuel cell systems with high power density. Here we report a facile and cost-effective strategy to synthesis of ultrafine Pd nanoparticles (NPs) supported on N and S dual-doped graphene (NS-G) nanosheets as multifunctional electrocatalysts for both direct formic acid fuel cell and direct methanol fuel cell. The incorporation of N and S atoms into graphene frameworks is achieved by a thermal treatment process, followed by the controlled growth of Pd NPs via a solvothermal approach. Owning to the unique structural features as well as the strong synergistic effects, the resulting Pd/NS-G hybrid exhibits outstanding electrocatalytic performance toward both formic acid and methanol electro-oxidation, such as higher anodic peak current densities and more exceptional catalytic stability than those of Pd/Vulcan XC-72R and Pd/undoped graphene catalysts. These findings open up new possibility in the construction of advanced Pd-based catalysts, which is conducive to solving the current bottlenecks of fuel cell technologies.

  7. 4-Hydroxyphenylacetic acid oxidation in sulfate and real olive oil mill wastewater by electrochemical advanced processes with a boron-doped diamond anode.

    Science.gov (United States)

    Flores, Nelly; Cabot, Pere Lluís; Centellas, Francesc; Garrido, José Antonio; Rodríguez, Rosa María; Brillas, Enric; Sirés, Ignasi

    2017-01-05

    The degradation of 4-hydroxyphenylacetic acid, a ubiquitous component of olive oil mill wastewater (OOMW), has been studied by anodic oxidation with electrogenerated H 2 O 2 (AO-H 2 O 2 ), electro-Fenton (EF) and photoelectro-Fenton (PEF). Experiments were performed in either a 0.050M Na 2 SO 4 solution or a real OOMW at pH 3.0, using a cell with a boron-doped diamond (BDD) anode and an air-diffusion cathode for H 2 O 2 generation. Hydroxyl radicals formed at the BDD surface from water oxidation in all processes and/or in the bulk from Fenton's reaction between added Fe 2+ and generated H 2 O 2 in EF and PEF were the main oxidants. In both matrices, the oxidation ability of the processes increased in the order AO-H 2 O 2 acid decay obeyed a pseudo-first-order kinetics. The PEF treatment of 1.03mM 4-hydroxyphenylacetic acid in 0.050M Na 2 SO 4 allowed 98% mineralization at 360min even at low current density, whereas 80% mineralization and a significant enhancement of biodegradability were achieved with the real OOMW. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. An “on-off-on” fluorescent nanoprobe for recognition of chromium(VI) and ascorbic acid based on phosphorus/nitrogen dual-doped carbon quantum dot

    Energy Technology Data Exchange (ETDEWEB)

    Gong, Xiaojuan, E-mail: gxj1124@sxu.edu.cn [Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); Liu, Yang; Yang, Zhenhua; Shuang, Shaomin [Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China); Zhang, Zeyu [Faculty of Science, Beijing University of Chemical Technology, Beijing, 100029 (China); Dong, Chuan, E-mail: dc@sxu.edu.cn [Institute of Environmental Science, School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006 (China)

    2017-05-22

    Chromium (VI) [Cr(VI)] is a harsh environmental contaminates and has been proved to be highly toxic, carcinogenic and mutagenic. Therefore, developing an inexpensive, good selective and highly sensitive nanoprobe for the detection of Cr(VI) is in urgent demand. Recently, the highly fluorescent carbon quantum dots (CQDs) have been successfully utilized as efficient fluorescent nanoprobes for the detection of ions, pH and molecular substances. In this work, an “on-off” fluorescence phosphorus/nitrogen dual-doped CQDs (PNCQDs) probe was developed for the determination of Cr(VI) based on inner filter effect (IFE). The proposed PNCQDs nanoprobe shows its distinct merits of simplicity, convenience, fast implementation, good selectivity and high sensitivity towards Cr(VI), allowing its potential application in the determination of Cr(VI) in environment and biosystem. In addition, the chelation effect of the functional groups in reductant and Cr(VI), and the easy-conversion of Cr(VI) to reduced states (i.e. Cr(III) and Cr(0)) by reductants makes the minimization of IFE with a concomitant recovery of PNCQDs fluorescence possible. Hence, the PNCQDs/Cr(VI) hybrid was used as an “off-on” fluorescence probe for sensing ascorbic acid (AA), which is a model reductant. For the detection of Cr(VI), the linear range and the limit of detection achieved were 1.5–30 μmol/L and 23 nmol/L, respectively. For the detection of AA, the linear range and the limit of detection obtained were 5.0–200 μmol/L and 1.35 μmol/L, respectively. The as-constructed “on-off-on” PNCQDs fluorescent nanoprobe was successfully applied for detecting Cr(VI) and AA in biosystem. Furthermore, the as-constructed fluorescent sensing system was successfully applied to the analyses of AA in fresh fruits and in commercial fruit juices with satisfactory results. - Highlights: • Fast synthesis of phosphorus/nitrogen dual-doped CQDs (PNCQDs) by acid-base neutralization carbonization method.

  9. Increasing the fill factor of inverted P3HT:PCBM solar cells through surface modification of Al-doped ZnO via phosphonic acid-anchored C60 SAMs

    Energy Technology Data Exchange (ETDEWEB)

    Stubhan, Tobias [Institute of Materials for Electronics and Energy Technology (I-MEET), Friedrich-Alexander-University, Erlangen-Nuremberg, Erlangen (Germany); Salinas, Michael; Halik, Marcus [Organic Materials and Devices (OMD)-Institute of Polymer Materials, University Erlangen-Nuremberg, Erlangen (Germany); Ebel, Alexander; Hirsch, Andreas [Institute for Organic Chemistry II, Friedrich-Alexander-University, Erlangen-Nuremberg, Erlangen (Germany); Krebs, Frederick C. [Risoe National Laboratory for Sustainable Energy, Technical University of Denmark, Roskilde (Denmark); Brabec, Christoph J. [Institute of Materials for Electronics and Energy Technology (I-MEET), Friedrich-Alexander-University, Erlangen-Nuremberg, Erlangen (Germany); Bavarian Center for Applied Energy Research (ZAE Bayern), Erlangen (Germany)

    2012-05-15

    The influence of aluminum-doped zinc oxide (AZO) electron extraction layers modified with self-assembled monolayers (SAMs) on inverted polymer solar cells is investigated. It is found that AZO modification with phosphonic acid-anchored Fullerene-SAMs leads to a reduction of the series resistance, while increasing the parallel resistance. This results in an increased efficiency from 2.9 to 3.3%. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Electronically tailoring 3D flower-like graphene via alumina doping and incorporating Co as an efficient oxygen electrode catalyst in both alkaline and acid media

    Science.gov (United States)

    Ma, Xiu-Xiu; He, Xing-Quan

    2017-06-01

    3D graphene-based electrode catalysts have intrigued tremendous research in energy conversion and storage systems not only for the intrinsic properties of graphene, but also due to its high active density for the oxygen electrode reaction with efficient mass and electron transports. In this work, we try to electronically tailor 3D nitrogen-doped graphene (NG) using alumina (Al), and obtain the flower-like structure with a high Brunauer-Emmett-Teller (BET) surface area and abundant active sites, as a result, pure cobalt nanoparticles are easily confined. Physical characterizations confirm that this natural tuning of graphene by Al causes the increasing of surface defects, as a result, the physicochemical stability of Al and graphene is improved, and vice versa, consequently, the co-modification of Al and Co induce outstanding oxygen reduction reaction (ORR) performance including distinct onset potential, large diffusion limiting current density, kinetic current density and good stability, which are comparable with those of 20 wt% Pt/C in both alkaline and acidic media; in addition, the fabricated composite also delivers prior oxygen evolution reaction activity, superior to the benchmark RuO2. This hybrid herein exhibits a combined ORR and OER potential gap of 0.745 V, rivaling state-of-the-art bifunctional oxygen electrode catalysts.

  11. Multifunctionalized reduced graphene oxide-doped polypyrrole/pyrrolepropylic acid nanocomposite impedimetric immunosensor to ultra-sensitively detect small molecular aflatoxin B₁.

    Science.gov (United States)

    Wang, Dan; Hu, Weihua; Xiong, Yonghua; Xu, Yang; Li, Chang Ming

    2015-01-15

    Aflatoxin B1 (AFB1), an aflatoxin is extremely toxic among mycotoxins in contaminated food products but it is very difficult to be quantitatively detected by existing methods. Impedimetric immunosensor is an advantageously label-free and fast assay. Nevertheless, its applications are limited by low sensitivity when the target molecule is small such as AFB1 due to relatively low impedance change during detection. Herein for the first time reduced graphene oxide (rGO) is nanocomposed with polypyrrole (PPy) and pyrrolepropylic acid (PPa) as a unique sensing platform, in which rGO greatly improves the conductivity and stability, PPa provides covalent linkers for probe immobilization and PPy endows the film electroactivity from its inherent electrochemical doping/dedoping property for impedance measurements, thus significantly improving the sensitivity to detect AFB1 in a range of 10 fg mL(-1) to 10 pg mL(-1) with high specificity and good reproducibility. This work demonstrates a novel method to sensitively detect small molecule by using immunoassay. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Enhancing the electrochemical oxidation of acid-yellow 36 azo dye using boron-doped diamond electrodes by addition of ferrous ion

    Energy Technology Data Exchange (ETDEWEB)

    Villanueva-Rodriguez, M.; Hernandez-Ramirez, A. [Universidad Autonoma de Nuevo Leon, Facultad de Ciencias Quimicas, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, NL. 66400 (Mexico); Peralta-Hernandez, J.M., E-mail: jperalta@fcq.uanl.mx [Universidad Autonoma de Nuevo Leon, Facultad de Ciencias Quimicas, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, NL. 66400 (Mexico); Bandala, Erick R.; Quiroz-Alfaro, Marco A. [Universidad de Las Americas - Puebla, Escuela de Ingenieria y Ciencias, Sta. Catarina Martir - Cholula, Puebla 72820 (Mexico)

    2009-08-15

    This work shows preliminary results on the electrochemical oxidation process (EOP) using boron-doped diamond (BDD) electrode for acidic yellow 36 oxidation, a common azo dye used in textile industry. The study is centred in the synergetic effect of ferrous ions and hydroxyl free radicals for improving discoloration of azo dye. The assays were carried out in a typical glass cell under potentiostatic conditions. On experimental conditions, the EOP was able to partially remove the dye from the reaction mixture. The reaction rate increased significantly by addition of Fe{sup 2+} (1 mM as ferrous sulphate) to the system and by (assumed) generation of ferrate ion [Fe(VI)] over BDD electrode. Ferrate is considered as a highly oxidizing reagent capable of removing the colorant from the reaction mixture, in synergistic action with the hydroxyl radicals produced on the BDD surface. Further increases in the Fe{sup 2+} concentration lead to depletion of the reaction rate probably due to the hydroxyl radical scavenging effect of Fe{sup 2+} excess in the system.

  13. Aptameric Recognition-Modulated Electroactivity of Poly(4-Styrenesolfonic Acid-Doped Polyaniline Films for Single-Shot Detection of Tetrodotoxin

    Directory of Open Access Journals (Sweden)

    Gertrude Fomo

    2015-09-01

    Full Text Available The work being reported is the first electrochemical sensor for tetrodotoxin (TTX. It was developed on a glassy carbon electrodes (C that was modified with poly(4-styrenesolfonic acid-doped polyaniline film (PANI/PSSA. An amine-end functionalized TTX-binding aptamer, 5′-NH2-AAAAATTTCACACGGGTGCCTCGGCTGTCC-3′ (NH2-Apt, was grafted via covalent glutaraldehyde (glu cross-linking. The resulting aptasensor (C//PANI+/PSSA-glu-NH2-Apt was interrogated by cyclic voltammetry (CV and electrochemical impedance spectroscopy (EIS in sodium acetate buffer (NaOAc, pH 4.8 before and after 30 min incubation in standard TTX solutions. Both CV and EIS results confirmed that the binding of the analyte to the immobilized aptamer modulated the electrochemical properties of the sensor: particularly the charge transfer resistance (Rct of the PANI+/PSSA film, which served as a signal reporter. Based on the Rct calibration curve of the TTX aptasensor, the values of the dynamic linear range (DLR, sensitivity and limit of detection (LOD of the sensor were determined to be 0.23–1.07 ng·mL−1 TTX, 134.88 ± 11.42 Ω·ng·mL−1 and 0.199 ng·mL−1, respectively. Further studies are being planned to improve the DLR as well as to evaluate selectivity and matrix effects in real samples.

  14. Optical sensing of 3-phenoxybenzoic acid as a pyrethroid pesticides exposure marker by surface imprinting polymer capped on manganese-doped zinc sulfide quantum dots

    Directory of Open Access Journals (Sweden)

    Vivek Pandey

    2015-09-01

    Full Text Available The present communication deals with the synthesis of luminescent Mn-doped ZnS quantum dots (QDs anchored to surface imprinted polymer for the optical sensing of 3-phenoxy benzoic acid (3-PBA in urine samples. The combination of sensing and surface functionalization not only improves the selectivity of the method, but also increases the optosensing ability of the material for non-phosphorescent substances. The developed material was utilized for the selective and sensitive detection of 3-PBA in urine samples. The proposed method shows good linearity with a regression coefficient (R2 of 0.98. The limit of detection was found to be 0.117 μM. The method has an acceptable precision and accuracy which are found to be less than 8% and 80–90% respectively at three different concentrations. The quenching constant of quantum dot-molecular imprinted polymer was found to be 3.4 times higher to that of the quantum dot-non imprinted polymer (QD-NIP as calculated by Stern–Volmer equation. The sensing method developed has shown immense utility to detect 3-PBA in complex biological samples like urine.

  15. Photodegradation of 4-chlorophenoxyacetic acid under visible LED activated N-doped TiO2 and the mechanism of stepwise rate increment of the reused catalyst.

    Science.gov (United States)

    Abdelhaleem, Amal; Chu, Wei

    2017-09-15

    Photodegradation of 4-chlorophenoxyacetic acid (4-CPA) was systematically investigated using N-doped TiO2 (N-TiO2) under commercially available visible light emitting diode (Vis LED) as a novel Vis LED illumination in photocatalysis applications. The synergetic effect of Vis LED/N-TiO2 process was studied in detail by varying reaction conditions including the initial concentration of 4-CPA, catalyst dosage, light intensity, and initial pH. Additionally, the influence of inorganic anions and radical scavengers on the performance of the Vis LED/N-TiO2 process was also evaluated. The Vis LED/N-TiO2 was found to be a promising process in terms of mineralization of 4-CPA. It is interesting to note that the performance of this process was not reduced after successive usage of the recycled catalyst; instead, the reaction rate of 4-CPA decay actually increased by using the spent catalyst. The mechanism behind rate enhancement after/during reuse was explored by XPS and FT-IR analyses and it was proven that hydroxyl groups can be incorporated into the catalyst surface by the repeated wetting of N-TiO2 after each reuse. This facilitates the formation of hydrogen bonds between the 4-CPA molecules and N-TiO2, thereby allowing more collisions between the trapped 4-CPA and radicals at the interface of bulk solution and catalyst, respectively. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. High-Performance Flexible Solid-State Carbon Cloth Supercapacitors Based on Highly Processible N-Graphene Doped Polyacrylic Acid/Polyaniline Composites

    Science.gov (United States)

    Wang, Yongguang; Tang, Shaochun; Vongehr, Sascha; Ali Syed, Junaid; Wang, Xiangyu; Meng, Xiangkang

    2016-01-01

    Improving the solubility of conductive polymers to facilitate processing usually decreases their conductivity, and they suffer from poor cycling stability due to swelling-shrinking during charging cycles. We circumvent these problems with a novel preparation method for nitrogen-doped graphene (NG) enhanced polyacrylic acid/polyaniline (NG-PAA/PANI) composites, ensuring excellent processibility for scalable production. The content of PANI is maximized under the constraint of still allowing defect-free coatings on filaments of carbon cloth (CC). The NG content is then adjusted to optimize specific capacitance. The optimal CC electrodes have 32 wt.% PANI and 1.3 wt.% NG, thus achieving a high capacitance of 521 F/g at 0.5 F/g. A symmetric supercapacitor made from 20 wt.% PANI CC electrodes has more than four times the capacitance (68 F/g at 1 A/g) of previously reported flexible capacitors based on PANI-carbon nanotube composites, and it retains the full capacitance under large bending angles. The capacitor exhibits high energy and power densities (5.8 Wh/kg at 1.1 kW/kg), a superior rate capability (still 81% of the 1 A/g capacitance at 10 A/g), and long-term electrochemical stability (83.2% retention after 2000 cycles). PMID:26883179

  17. TiO2structures doped with noble metals and/or graphene oxide to improve the photocatalytic degradation of dichloroacetic acid.

    Science.gov (United States)

    Ribao, Paula; Rivero, Maria J; Ortiz, Inmaculada

    2017-05-01

    Noble metals have been used to improve the photocatalytic activity of TiO 2 . Noble metal nanoparticles prevent charge recombination, facilitating electron transport due to the equilibration of the Fermi levels. Furthermore, noble metal nanoparticles show an absorption band in the visible region due to a high localized surface plasmon resonance (LSPR) effect, which contributes to additional electron movements. Moreover, systems based on graphene, titanium dioxide, and noble metals have been used, considering that graphene sheets can carry charges, thereby reducing electron-hole recombination, and can be used as substrates of atomic thickness. In this work, TiO 2 -based nanocomposites were prepared by blending TiO 2 with noble metals (Pt and Ag) and/or graphene oxide (GO). The nanocomposites were mainly characterized via transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR), Raman spectroscopy, and photocurrent analysis. Here, the photocatalytic performance of the composites was analyzed via oxidizing dichloroacetic acid (DCA) model solutions. The influence of the noble metal load on the composite and the ability of the graphene sheets to improve the photocatalytic activity were studied, and the composites doped with different noble metals were compared. The results indicated that the platinum structures show the best photocatalytic degradation, and, although the presence of graphene oxide in the composites is supposed to enhance their photocatalytic performance, graphene oxide does not always improve the photocatalytic process. Graphical abstract It is a schematic diagram. Where NM is Noble Metal and LSPR means Localized Surface Plasmon Resonance.

  18. Lysine-doped polypyrrole/spider silk protein/poly(l-lactic) acid containing nerve growth factor composite fibers for neural application.

    Science.gov (United States)

    Zhang, Hong; Wang, Kefeng; Xing, Yiming; Yu, Qiaozhen

    2015-11-01

    Lysine-doped polypyrrole (PPy)/regenerated spider silk protein (RSSP)/poly(l-lactic) acid (PLLA)/nerve growth factor (NGF) (L-PRPN) composite scaffold was fabricated by co-axial electrospraying and electrospinning. This L-PRPN composite scaffold had a structure of microfibers with a core-shell structure as the stems and nanofibers as branches. Assessment in vitro demonstrated that the L-PRPN composite micro/nano-fibrous scaffold could maintain integrated structure for at least 4months and the pH value of PBS at about 7.28. It had good biocompatibility and cell adhesion and relatively stable conductivity. PC 12 cells cultured on this scaffold, anisotropic cell-neurite-cell-neurite or neurite-neurite sheets were formed after being cultured for 6days. Evaluations in vivo also showed that L-PRPN composite fibrous conduit was effective at bridging 2.0cm sciatic nerve gap in adult rat within 10months. This conduit and electrical stimulation (ES) through it promoted Schwann cell migration and axonal regrowth. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Simple quantitation of formoterol and 11-nor-Δ(9)-tetrahydrocannabinol-9-carboxylic acid in human urine by liquid chromatography-tandem mass spectrometry in doping control.

    Science.gov (United States)

    Lee, Kang Mi; Kim, Ho Jun; Son, Junghyun; Park, Ju-Hyung; Kwon, Oh-Seung; Lee, Jaeick

    2014-09-15

    11-nor-Δ(9)-tetrahydrocannabinol-9-carboxylic acid (THC-COOH) and formoterol are newly revised prohibited threshold substances (150 ng/mL for THC-COOH and 40 ng/mL for formoterol) by the World Anti-Doping Agency (WADA). In continuation of our direct quantitation work of the prohibited threshold substances, direct LC-MS/MS methods combined with a simple sample preparation procedure have been developed and validated for the measurement of these two threshold substances in urine samples. After the enzymatic hydrolysis of urine samples, the resulting samples were diluted with acetonitrile and centrifuged. The supernatant was directly analyzed by LC-MS/MS using the selected reaction monitoring mode. The calibration curve range of the assay was ranged over 50-200% of the threshold value according to WADA guidelines. The limit of detection and limit of quantification were 6.1 and 18.4 ng/mL for THC-COOH and 2.0 and 6.2 ng/mL for formoterol, respectively. Intra- and inter-day precisions were between 2.08% and 7.28% and the accuracies ranged from 95.16% to 104.49%. The present methods were successfully applied to the analysis of the proficiency test samples. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Doping droops.

    Science.gov (United States)

    Chaturvedi, Aditi; Chaturvedi, Harish; Kalra, Juhi; Kalra, Sudhanshu

    2007-01-01

    Drug abuse is a major concern in the athletic world. The misconception among athletes and their coaches is that when an athlete breaks a record it is due to some "magic ingredient" and not because of training, hard work, mental attitude and championship performance. The personal motivation to win in competitive sports has been intensified by national, political, professional and economic incentives. Under this increased pressure athletes have turned to finding this "magic ingredient". Athlete turns to mechanical (exercise, massage), nutritional (vitamins, minerals), pharmacological (medicines) or gene therapies to have an edge over other players. The World Anti-Doping Agency (WADA) has already asked scientists to help find ways to prevent gene therapy from becoming the newest form of doping. The safety of the life of athletes is compromised with all forms of doping techniques, be it a side effect of a drug or a new technique of gene doping.

  1. Multifunctional electroactive electrospun nanofiber structures from water solution blends of PVA/ODA-MMT and poly(maleic acid-alt-acrylic acid): effects of Ag, organoclay, structural rearrangement and NaOH doping factors

    Science.gov (United States)

    Şimşek, Murat; Rzayev, Zakir M. O.; Bunyatova, Ulviya

    2016-06-01

    Novel multifunctional colloidal polymer nanofiber electrolytes were fabricated by green reactive electrospinning nanotechnology from various water solution/dispersed blends of poly (vinyl alcohol-co-vinyl acetate) (PVA)/octadecyl amine-montmorillonite (ODA-MMT) as matrix polymer nanocomposite and poly(maleic acid-alt-acrylic acid) (poly(MAc-alt-AA) and/or its Ag-carrying complex as partner copolymers. Polymer nanofiber electrolytes were characterized using FTIR, XRD, thermal (DSC, TGA-DTG), SEM, and electrical analysis methods. Effects of partner copolymers, organoclay, in situ generated silver nanoparticles (AgNPs), and annealing procedure on physical and chemical properties of polymer composite nanofibers were investigated. The electrical properties (resistance, conductivity, activation energy) of nanofibers with/without NaOH doping agent were also evaluated. This work presented a structural rearrangement of nanofiber mats by annealing via decarboxylation of anhydride units with the formation of new conjugated double bond sites onto partner copolymer main chains. It was also found that the semiconductor behaviors of nanofiber structures were essentially improved with increasing temperature and fraction of partner copolymers as well as presence of organoclay and AgNPs in nanofiber composite.

  2. Electrochemical Performance of a Carbon Nanotube/La-Doped TiO2 Nanocomposite and its Use for Preparation of an Electrochemical Nicotinic Acid Sensor

    Directory of Open Access Journals (Sweden)

    Hanxing Liu

    2008-11-01

    Full Text Available A carbon nanotube/La-doped TiO2 (La-TiO2 nanocomposite (CLTN was prepared by a procedure similar to a complex/adsorption process. Scanning electron microscopy (SEM images show that the La-TiO2 distributes on the carbon nanotube walls. The CLTN was mixed with paraffin to form a CLTN paste for the CLTN paste electrode (CLTNPE. The electrochemical characteristics of CLTNPE were compared with that of conventional carbon electrodes such as the carbon paste electrode (CPE and glass carbon electrode (GC. The CLTNPE exhibits electrochemical activity and was used to investigate the electrochemistry of nicotinic acid (NA. The modified electrode has a strong electrocatalytic effect on the redox of NA. The cyclic voltammetry (CV redox potential of NA at the CLTNPE is 320 mV. The oxidation process of NA on the CLTNPE is pH dependent. A sensitive chronoamperometric response for NA was obtained covering a linear range from 1.0×10-6 mol·L-1 to 1.2×10-4 mol·L-1, with a detection limit of 2.7×10-7 mol·L-1. The NA sensor displays a remarkable sensitivity and stability. The mean recovery of NA in the human urine is 101.8%, with a mean variation coefficient (RSD of 2.6%.

  3. Enhanced degradation of perfluorooctanoic acid using dielectric barrier discharge with La/Ce-doped TiO2.

    Science.gov (United States)

    Li, Shanping; Wang, Xiaoping; Liu, Lijun; Guo, Yongbo; Mu, Qinglin; Mellouki, Abdelwahid

    2017-06-01

    A synergistic system of dielectric barrier discharge (DBD) combined with La/Ce-TiO 2 was developed to investigate the decomposition performance of the environmentally persistent perfluorooctanoic acid (PFOA). The La/Ce-TiO 2 was modified by sol-gel method and characterized by XRD, SEM, and energy dispersive X-ray. The effects of PFOA concentration, applied voltage, initial pH, liquid conductivity, and additives on the removal rate of PFOA were explored. The results showed that the La/Ce-TiO 2 exhibited excellent catalytic effects on PFOA degradation in DBD system. When the applied voltage, PFOA concentration, pH value, and solution volume were 75 V, 100 mg/L, 3.63, and 1000 mL, respectively, the removal efficiency of PFOA was up to 97.5% by adding La 4 Ce 1 -TiO 2 in DBD. The corresponding defluorination ratio, TOC removal, and decomposition yield were 62.2%, 57.3%, and 37 g/kWh, respectively. Furthermore, five main intermediates including CF 3 (CF 2 ) 6 H, CF 3 (CF 2 ) 5 COOH, CF 3 (CF 2 ) 5 COH, CF 3 (CF 2 ) 4 COOH, and CF 3 CF 2 CF 3 were identified with LC-MS, and the degradation pathways of PFOA were proposed. The degradation mechanisms revealed that hydroxyl radicals play a significant role in the degradation of PFOA in the synergistic system.

  4. Significant improvement in visible light photocatalytic activity of Fe doped TiO2 using an acid treatment process

    Science.gov (United States)

    Moradi, Vahid; Jun, Martin B. G.; Blackburn, Arthur; Herring, Rodney A.

    2018-01-01

    Transition metal dopants have been used to decrease the band gap energy of TiO2 for visible light photocatalytic purposes. Fe3+ is a good dopant candidate owing to its capability to decrease the band gap energy and enhance the electron/hole trapping. However, in previous studies the photocatalytic activity of Fe-TiO2 was around 40-50% for a reaction time of ∼300 min. Herein, using HRTEM it was found out that the photocatalytic activity of Fe-TiO2 is limited by an amorphous contamination layer on the surface of the Fe-TiO2 nanoparticles. The contamination layer was determined to be composed of iron oxide by XPS surface analysis. The contamination layer was successfully removed using an acid treatment process comprising of HCl solution. Using the cleaned Fe-TiO2 nanoparticles, the photocatalytic activity measured utilizing a solution of 20 mg L-1 methyl orange (MO) was significantly increased from 24% to 98% within 60 min of reaction time under visible light illumination.

  5. Electrocatalysis of anodic oxygen-transfer reactions: Oxidation of phenol and benzene at bismuth-doped lead dioxide electrodes in acidic solutions

    Energy Technology Data Exchange (ETDEWEB)

    Kawagoe, K.T.; Johnson, D.C. (Ames Lab., IA (United States))

    1994-12-01

    The electrocatalytic activities are compared for pure [beta]-lead dioxide electrodes and bismuth-doped lead dioxide electrodes for oxidation of dimethylsulfoxide (DMSO), phenol, and benzene in acidic media. A correlation is observed between the bismuth content of Bi-PbO[sub 2] films on Au disk electrodes and the apparent heterogeneous rate constant for conversion of DMSO to DMSO[sub 2]. The oxidation of phenol occurs at a transport-limited rate for both the PbO[sub 2] and Bi-PbO[sub 2] film electrodes; however, the Bi-PbO[sub 2] electrodes exhibit significantly greater stability against surface fouling by polymeric films. This is a direct benefit of the greater electrocatalytic activity of Bi-PbO[sub 2] electrodes for oxidation of phenol beyond the phenolic radical. A ring-disk experiment for benzene oxidation at a Bi-PbO[sub 2] disk demonstrates that o-benzoquinone and p-benzoquinone are produced at the disk in the ratio ca. 0.25. However, the total ring current for reduction of these products from the disk reaction is significantly below that predicted from the disk current, and it must be concluded that a significant amount of electroinactive species is produced at the disk. This production probably corresponds to a ring-opening reaction with production of one or more organic acids. The product solution from exhaustive electrolysis of benzene contains p-benzoquinone as the only electroactive product; hence, the o-benzoquinone is concluded to undergo further oxidation at the Bi-PbO[sub 2] electrode to one or more electroinactive products. This is part of a larger program motivated by the search for new catalytic anode materials for achieving electrolytic production of useful compounds by oxidation of toxic chemical wastes. Also of interest is the total oxidative degradation of toxic organic wastes to their corresponding elemental oxides (CO[sub 2], etc.), a technology referred to as electrochemical incineration.

  6. An "on-off-on" fluorescent nanoprobe for recognition of chromium(VI) and ascorbic acid based on phosphorus/nitrogen dual-doped carbon quantum dot.

    Science.gov (United States)

    Gong, Xiaojuan; Liu, Yang; Yang, Zhenhua; Shuang, Shaomin; Zhang, Zeyu; Dong, Chuan

    2017-05-22

    Chromium (VI) [Cr(VI)] is a harsh environmental contaminates and has been proved to be highly toxic, carcinogenic and mutagenic. Therefore, developing an inexpensive, good selective and highly sensitive nanoprobe for the detection of Cr(VI) is in urgent demand. Recently, the highly fluorescent carbon quantum dots (CQDs) have been successfully utilized as efficient fluorescent nanoprobes for the detection of ions, pH and molecular substances. In this work, an "on-off" fluorescence phosphorus/nitrogen dual-doped CQDs (PNCQDs) probe was developed for the determination of Cr(VI) based on inner filter effect (IFE). The proposed PNCQDs nanoprobe shows its distinct merits of simplicity, convenience, fast implementation, good selectivity and high sensitivity towards Cr(VI), allowing its potential application in the determination of Cr(VI) in environment and biosystem. In addition, the chelation effect of the functional groups in reductant and Cr(VI), and the easy-conversion of Cr(VI) to reduced states (i.e. Cr(III) and Cr(0)) by reductants makes the minimization of IFE with a concomitant recovery of PNCQDs fluorescence possible. Hence, the PNCQDs/Cr(VI) hybrid was used as an "off-on" fluorescence probe for sensing ascorbic acid (AA), which is a model reductant. For the detection of Cr(VI), the linear range and the limit of detection achieved were 1.5-30 μmol/L and 23 nmol/L, respectively. For the detection of AA, the linear range and the limit of detection obtained were 5.0-200 μmol/L and 1.35 μmol/L, respectively. The as-constructed "on-off-on" PNCQDs fluorescent nanoprobe was successfully applied for detecting Cr(VI) and AA in biosystem. Furthermore, the as-constructed fluorescent sensing system was successfully applied to the analyses of AA in fresh fruits and in commercial fruit juices with satisfactory results. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Structural and transport effects of doping perfluorosulfonic acid polymers with the heteropoly acids, H3PW12O40 or H4SiW12O40

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Fanqin; Aieta, Niccolo V.; Dec, Steven F.; Horan, James L.; Williamson, Don; Frey, Matthew H.; Pham, Phat; Turner, John A.; Yandrasits, Michael A.; Hamrock, Steven J.; Herring, Andrew M.

    2007-12-01

    A perfluorosulfonic acid (PFSA) polymer with pendant side chain –O(CF2)4SO3H was doped with the heteropoly acids (HPAs), H3PW12O40 and H4SiW12O40. Infrared spectroscopy revealed a strong interaction between the HPA and the PFSA ionomer. Modes associated with the peripheral bonds of the HPA were shifted to lower wave numbers when doped into PFSA membranes. Small-angle X-ray scattering (SAXS) measurements showed the presence of large crystallites of HPA in the membrane with d spacings of ca. 10 Å, close to the lattice spacing observed in bulk HPA crystals. Under wet conditions the HPA was more dispersed and constrained the size of the sulfonic acid clusters to 20 Å at a 5 wt% HPA doping level, the same as in the vacuum treated ionomer samples. Under conditions of minimum hydration the HPA decreased the Ea for the self-diffusion of water from 27 to 15 kJ mol-1. The reverse trend was seen under 100% RH conditions. Proton conductivity measurements showed improved proton conductivity of the HPA doped PFSAs at a constant dew point of 80 °C for all temperatures up to 120 °C and at all relative hummidities up to 80%. The activation energy for proton conduction generally was lower than for the undoped materials at RH ≤80%. Significantly the Ea was 1/2 that of the undoped material at RHs of 40 and 60%. A practical proton conductivity of 113 mS cm-1 was observed at 100 °C and 80% RH.

  8. Gypsum (CaSO4·2H2O) Scaling on Polybenzimidazole and Cellulose Acetate Hollow Fiber Membranes under Forward Osmosis

    Science.gov (United States)

    Chen, Si Cong; Su, Jincai; Fu, Feng-Jiang; Mi, Baoxia; Chung, Tai-Shung

    2013-01-01

    We have examined the gypsum (CaSO4·2H2O) scaling phenomena on membranes with different physicochemical properties in forward osmosis (FO) processes. Three hollow fiber membranes made of (1) cellulose acetate (CA), (2) polybenzimidazole (PBI)/polyethersulfone (PES) and (3) PBI-polyhedral oligomeric silsesquioxane (POSS)/polyacrylonitrile (PAN) were studied. For the first time in FO processes, we have found that surface ionic interactions dominate gypsum scaling on the membrane surface. A 70% flux reduction was observed on negatively charged CA and PBI membrane surfaces, due to strong attractive forces. The PBI membrane surface also showed a slightly positive charge at a low pH value of 3 and exhibited a 30% flux reduction. The atomic force microscopy (AFM) force measurements confirmed a strong repulsive force between gypsum and PBI at a pH value of 3. The newly developed PBI-POSS/PAN membrane had ridge morphology and a contact angle of 51.42° ± 14.85° after the addition of hydrophilic POSS nanoparticles and 3 min thermal treatment at 95 °C. Minimal scaling and an only 1.3% flux reduction were observed at a pH value of 3. Such a ridge structure may reduce scaling by not providing a locally flat surface to the crystallite at a pH value of 3; thus, gypsum would be easily washed away from the surface. PMID:24957062

  9. A comprehensive review of PBI-based high temperature PEM fuel cells

    DEFF Research Database (Denmark)

    Simon Araya, Samuel; Zhou, Fan; Liso, Vincenzo

    2016-01-01

    The current status on the understanding of the various operational aspects of high temperature proton exchange membrane fuel cells (HT-PEMFC) has been summarized. The paper focuses on phosphoric acid-doped polybenzimidazole (PBI)-based HT-PEMFCs and an overview of the common practices of their de...

  10. Sulfur-Doped Porphyrinic Carbon Nanostructures Synthesized with Amorphous MoS2 for the Oxygen Reduction Reaction in an Acidic Medium.

    Science.gov (United States)

    Park, Hyun-Suk; Han, Sang-Beom; Kwak, Da-Hee; Lee, Gyu-Ho; Choi, In-Ae; Kim, Do-Hyoung; Ma, Kyeng-Bae; Kim, Min-Cheol; Kwon, Hye-Jin; Park, Kyung-Won

    2017-05-22

    To develop doped carbon nanostructures as non-precious metal cathode catalysts, nanocomposites were synthesized by using SBA-15 and 5,10,15,20-tetrakis(4-methoxyphenyl)porphyrin-iron(III) chloride with different ratios of amorphous MoS2 precursor. From various analyses, it was found that, during pyrolysis at 900 °C under an N2 atmosphere, the amorphous MoS2 precursor decomposed into Mo and S, facilitating the formation of graphene sheet-like carbon with MoC and doping of sulfur in the carbon. In the nanocomposite formed from 10 wt % MoS2 precursor (denoted as Mo/S/PC-10), most of the MoS2 was decomposed, thus forming S-doped carbon, which was grown on the MoC phase without crystalline MoS2 . Furthermore, Mo/S/PC-10 exhibited better performance in the oxygen reduction reaction (specific activity of 1.23 mA cm(-2) at 0.9 V and half-wave potential of 0.864 V) than a commercial Pt catalyst, owing to a heteroatom-doped carbon nanostructure with a fairly high specific surface area. In the polarization curve of the unit-cell performance measured at 80 °C under ambient pressure, Mo/S/PC-10 as a cathode catalyst exhibited an optimal power density of 314 mW cm(-2) and a current density of 280 mA cm(-2) at 0.6 V. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Niobium (V) doped bioceramics: evaluation of the hydrothermal route modified with citric acid and urea to obtain modified hydroxyapatite; Bioceramicas aditivadas com niobio (V): avaliacao da rota hidrotermica modificada com acido citrico e ureia para obtencao de hidroxiapatitas modificadas

    Energy Technology Data Exchange (ETDEWEB)

    Simomukay, E.; Souza, E.C.F. de; Antunes, S.R.M.; Borges, C.P.F.; Michel, M.D.; Antunes, A.C. [Universidade Estadual de Ponta Grossa (UEPG), Ponta Grossa, PR (Brazil)

    2016-01-15

    Synthetic hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}; HA) has become a widely used ceramic material for bone reconstruction due to its biocompatibility with the bone tissue. This biocompatibility as well as other physical and chemical properties of the hydroxyapatite can be modified by the addition of different ions to its structure. Niobium (V) ion has not been commonly used in the hydroxyapatite synthesis. The objective of this study was to evaluate the use of hydrothermal route in the niobium (V) doped hydroxyapatite synthesis. The route used the niobium ammonium oxalate (NH{sub 4}H{sub 2}[NbO(C{sub 2}O{sub 4}){sub 3}].3H{sub 2}O) complex as a niobium (V) ion precursor. The addition of citric acid and urea in the hydrothermal route is used for the control of synthesis pH and precipitation rate. Pure sample and sample added with 5.3 ppm of niobium (V) ion were prepared. The coexistence of other phases besides the hydroxyapatite was not observed in any of the samples through the use of X-ray diffraction and infrared spectroscopy (FTIR) techniques. The FTIR technique revealed the presence of hydroxyapatite characteristic functional groups. The scanning electron microscopy analysis showed the formation of agglomerates composed of round particles, confirmed by the transmission electron microscopy technique. The X-ray fluorescence spectroscopic analysis detected the presence of niobium in the doped sample. The results showed that niobium (V) doped hydroxyapatite can be synthesized by means of hydrothermal route, which may be considered as huge potential for future application in bioceramics. (author)

  12. Synthesis and characterization of Sn doped TiO{sub 2} photocatalysts: Effect of Sn concentration on the textural properties and on the photocatalytic degradation of 2,4-dichlorophenoxyacetic acid

    Energy Technology Data Exchange (ETDEWEB)

    Rangel-Vázquez, I.; Del Angel, G.; Bertin, V. [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael, Atlixco No 1865, México 09340 D.F. (Mexico); González, F. [Departamento de Ingeniería de Procesos e Hidráulica, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael, Atlixco No 1865, México 09340 D.F. (Mexico); Vázquez-Zavala, A.; Arrieta, A. [Departamento de Química, Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael, Atlixco No 1865, México 09340 D.F. (Mexico); Padilla, J.M. [Universidad Tecnológica del Centro de Veracruz, Área de Tecnología, Av. Universidad Carretera Federal Cuitláhuac-La Tinaja No. 350, Cuitláhuac, Veracruz 94910 (Mexico); Barrera, A. [Universidad de Guadalajara, Centro Universitario de la Ciénega, Av. Universidad, Número 1115, Col. Linda Vista, Apdo. Postal 106, Ocotlán Jal. (Mexico); Ramos-Ramirez, E. [Departamento de Química, División de Ciencias Naturales y Exactas, Campus Guanajuato de la Universidad de Guanajuato Noria Alta S/N, Col. Noria Alta, Guanajuato, Gto. C.P. 36050 (Mexico)

    2015-09-15

    Abstract: TiO{sub 2} and Sn-doped TiO{sub 2} materials were prepared by sol–gel method using titanium and tin alkoxides at different Sn concentration (0.1 mol%, 0.5 mol%, 1 mol%, 3 mol% and 5 mol%). Samples were characterized by thermo gravimetric analyzer with differential scanning calorimeter (TGA–DSC), X-ray Rietveld refinement, N{sub 2} adsorption (BET), transmission electron microscopy (TEM), UV–vis spectroscopies technology and Raman spectroscopy. Only anatase phase was observed in pure TiO{sub 2}, whereas anatase and brookite were obtained in Sn-doped TiO{sub 2} samples. Sn dopant acts as a promoter in phase transformation of TiO{sub 2}. The Rietveld refinements method was used to determine the relative weight of anatase and brookite, and crystallite size as a function of Sn concentration after calcination of samples at 673 K. It was also demonstrated the incorporation of Sn{sup 4+} into the anatase TiO{sub 2} structure. Sn{sup 4+} inhibits the growth of TiO{sub 2} crystallite size, which leads to an increase of the specific surface area of TiO{sub 2}. From XRD analysis, the solid solution limit of Sn{sup 4+} into TiO{sub 2} is 5 mol% Sn. The photocatalytic activity on Sn{sup 4+} doped TiO{sub 2} was determined for the 2,4-dichlorophenoxyacetic acid reaction. The maximum in activity was attributed to the coexistence of anatase and brookite phases in the appropriate ratio and crystallite size.

  13. Improved characteristics of conventional and inverted polymer photodetectors using phosphonic acid-based self-assembled monolayer treatment for interfacial engineering of Ga-doped ZnO electrodes

    Science.gov (United States)

    Kajii, Hirotake; Mohri, Yoshinori; Okui, Hiyuto; Kondow, Masahiko; Ohmori, Yutaka

    2018-03-01

    The characteristics of conventional and inverted polymer photodetectors based on a blend of a donor, poly(3-hexylthiophene) (P3HT), and an acceptor, fullerene derivative [6,6]phenyl-C61-butyric acid methyl ester (PCBM) using Ga-doped ZnO (GZO) electrodes modified by phosphonic acid-based self-assembled monolayer (SAM) treatment in a short time are investigated. Fluoroalkyl SAM, 1H,1H,2H,2H-perfluorooctane phosphonic acid (FOPA) treatment leads to efficient hole extraction from the active layer. The characteristics of the conventional device with GZO modified by FOPA treatment are almost the same as those with indium tin oxide modified by FOPA. Cs2CO3 and aminoalkyl SAM, 11-aminoundecylphosphonic acid (11-AUPA) treatments suppress the hole injection from GZO to the organic layer. For the inverted devices with GZO cathodes using Cs2CO3 and 11-AUPA, the dark current decreases, which results in the improved photodetector detectivity. An inverted device with both Cs2CO3 and 11-AUPA exhibits incident-photon-to-current conversion efficiency (IPCE) of approximately 65% (80%) at 0 V (‑6 V) under light irradiation (λ = 500 nm), high on/off ratio, and improved durability. Improved open-circuit voltage and IPCE at low voltages are achieved by these treatments, which are related with the improved internal built-in field, the reduction of recombination probability in the vicinity of GZO, and the modified charge collection efficiency.

  14. Effects of Zn/citric acid mole fraction on the structure and luminescence properties of the un-doped and 1.5% Pb{sup 2+} doped ZnAl{sub 2}O{sub 4} powders synthesized by citrate sol–gel method

    Energy Technology Data Exchange (ETDEWEB)

    Motloung, S.V., E-mail: motloungsv@qwa.ufs.ac.za [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Dejene, F.B. [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Swart, H.C.; Ntwaeaborwa, O.M. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa)

    2015-07-15

    Un-doped and 1.5% Pb{sup 2+}doped zinc aluminate (ZnAl{sub 2}O{sub 4}) was successfully prepared at a relatively low temperature (~80 °C) using the sol–gel process. The Zn/citric acid (CA) mole fraction was varied from 0.083 to 1.3. The X-ray diffraction (XRD) data revealed that most of the annealed samples consist of the cubic ZnAl{sub 2}O{sub 4} structure with ZnO impurities. The surface morphology of the phosphors was influenced by the Zn/CA mole fractions. The increase in the CA content lead to the morphological evolution and transformation from small particles to rods-like-needles. The nanopowder samples exhibited violet luminescence that varied from 400 to 410 nm, which suggested that the CA content affected the bandgap energy of the host. The results suggest that the emission originated either from the host, Pb{sup 2+} or ZnO impurities. Emission at 400 nm is attributed to the oxygen vacancies (V{sub 0}{sup *}) in the host and emission peak at 410 nm is attributed to the intrinsic defects emission of ZnO, while the emission at 552 nm is attributed to the second order emission of the excitation wavelength. The emission intensity was influenced by the Zn/CA mole fractions. The CIE colour coordinates of all samples are close to each other in the blue region. Two distinct peaks were observed at around 160 and 385 °C in thermo luminescence (TL) glow curve, which indicates that there are two set of traps. - Highlights: • Un-doped and 1.5% Pb{sup 2+}doped zinc aluminate (ZnAl{sub 2}O{sub 4}) was successfully prepared at a relatively low temperature (~80 °C) using the sol–gel process. • The increase in the catalyst content lead to the morphological evolution from small particles to rods-like-needles. • The catalyst content affected the band gap energy of the host. • Results showed that the emission can only arise from the host and ZnO impurities. • CIE colour coordinates of all samples is situated in the blue region of the chart.

  15. Nanostructured Samarium Doped Fluorapatites and Their Catalytic Activity towards Synthesis of 1,2,4-Triazoles

    National Research Council Canada - National Science Library

    Gangu, Kranthi Kumar; Maddila, Suresh; Maddila, Surya Narayana; Jonnalagadda, Sreekantha B

    2016-01-01

    ...) and their properties. The nanostructured Sm doped fluorapatites (Sm-FAp) were prepared by a co-precipitation method using four different amino acids, namely glutamic acid, aspartic acid, glycine and histidine...

  16. Effect of doping on TSD relaxation in cellulose acetate films

    Indian Academy of Sciences (India)

    Unknown

    cooperative motion with adjoining segments of the main polymer chain. The peak currents, released charge and activation energies associated with the peaks are affected by AA doping. The effect of doping with acrylic acid on the discharge current indicates the formation of molecular aggregates. Keywords. TSD relaxation ...

  17. Gene doping : an overview and current implications for athletes

    NARCIS (Netherlands)

    van der Gronde, Toon; de Hon, Olivier; Haisma, Hidde J.; Pieters, Toine

    The possibility of gene doping, defined as the transfer of nucleic acid sequences and/or the use of normal or genetically modified cells to enhance sport performance, is a real concern in sports medicine. The abuse of knowledge and techniques gained in the area of gene therapy is a form of doping,

  18. Gene doping: an overview and current implications for athletes

    NARCIS (Netherlands)

    van der Gronde, T.; de Hon, O.; Haisma, H.J.; Pieters, T.

    2013-01-01

    The possibility of gene doping, defined as the transfer of nucleic acid sequences and/or the use of normal or genetically modified cells to enhance sport performance, is a real concern in sports medicine. The abuse of knowledge and techniques gained in the area of gene therapy is a form of doping,

  19. On the electrocatalytic activity of nitrogen-doped reduced graphene ...

    Indian Academy of Sciences (India)

    The heteroatom-doped graphene/reduced graphene oxide (rGO)is very promising and the nitrogen-doped rGO (N-rGO) is emerging as a new inexpensive electrocatalyst foroxygen reduction reaction (ORR). Herein, we describe the effect of the chemical nature and amount of nitrogenin N-rGO towards ORR in acidic solution ...

  20. Electrochemical oxidation of acid black 210 dye on the boron-doped diamond electrode in the presence of phosphate ions: Effect of current density, pH, and chloride ions

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Carla Regina [Departamento de Quimica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes, 3900, CEP 14040-901, Ribeirao Preto, SP (Brazil); Montilla, Francisco; Morallon, Emilia [Departamento de Quimica Fisica, Universidad de Alicante, Apartado de Correos 99, E-03080, Alicante (Spain); Olivi, Paulo [Departamento de Quimica, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes, 3900, CEP 14040-901, Ribeirao Preto, SP (Brazil)], E-mail: olivip@ffclrp.usp.br

    2009-11-30

    The electrochemical oxidation of acid black 210 dye (AB-210) on the boron-doped diamond (BDD) was investigated under different pH conditions. The best performance for the AB-210 oxidation occurred in alkaline phosphate solution. This is probably due to oxidizing agents such as phosphate radicals and peroxodiphosphate ions, which can be electrochemically produced with good yields on the BDD anode, mainly in alkaline solution. Under this condition, the COD (chemical oxygen demand) removal was higher than that obtained from the model proposed by Comninellis. Electrolyses performed in phosphate buffer and in the presence of chloride ions resulted in faster COD and color removals in acid and neutral solutions, but in alkaline phosphate solution, a better performance in terms of TOC removal was obtained in the absence of chloride. Moreover, organochloride compounds were detected in all electrolyses performed in the presence of chloride. The AB-210 electrooxidation on BDD using phosphate as supporting electrolyte proved to be interesting since oxidizing species generated from phosphate ions were able to completely degrade the dye without producing organochloride compounds.

  1. Proton conductive membranes based on doped sulfonated polytriazole

    Energy Technology Data Exchange (ETDEWEB)

    Boaventura, M.; Brandao, L.; Mendes, A. [Laboratorio de Engenharia de Processos, Ambiente e Energia (LEPAE), Faculdade de Engenharia da Universidade do Porto, Rua Roberto Frias, 4200-465 Porto (Portugal); Ponce, M.L.; Nunes, S.P. [GKSS Research Centre Geesthacht GmbH, Max Planck Str. 1, D-21502, Geesthacht (Germany)

    2010-11-15

    This work reports the preparation and characterization of proton conducting sulfonated polytriazole membranes doped with three different agents: 1H-benzimidazole-2-sulfonic acid, benzimidazole and phosphoric acid. The modified membranes were characterized by scanning electron microscopy (SEM), infrared spectra, thermogravimetric analysis (TGA), dynamical mechanical thermal analysis (DMTA) and electrochemical impedance spectroscopy (EIS). The addition of doping agents resulted in a decrease of the glass transition temperature. For membranes doped with 85 wt.% phosphoric acid solution proton conductivity increased up to 2.10{sup -3} S cm{sup -1} at 120 C and at 5% relative humidity. The performance of the phosphoric acid doped membranes was evaluated in a fuel cell set-up at 120 C and 2.5% relative humidity. (author)

  2. Doping in competition or doping in sport?

    Science.gov (United States)

    Lippi, Giuseppe; Franchini, Massimo; Guidi, Gian Cesare

    2008-01-01

    Since ancient times, competitive athletes have been familiar with the use of ergogenic aids and they will probably continue to use unfair and harmful substances in future, because their inclination to victory, along with the mirage of glory and money, will probably overcome health and legal risks. We searched PubMed using the term doping over the period 1990 to the present day. We also included non-English journals. By literature searching, it emerges that the phenomenon of doping is complex and multifaceted. It involves a number of causes and factors that do not originate solely in the athletic field, making universality its main feature. It is in fact observed in all ages and levels of competition, and it concerns all sports, even the most unpredictable. The high number of athletes testing positive for anti-doping controls attests that the current strategy might be analytically adequate to unmask most (but not all) doping practices, but it is probably ineffective to prevent athletes to dope and modify this upsetting trend. Growing points As doping parallels the use of medications, food supplements, alcohol and social drugs, a reinforced preventive policy is advisable. The current anti-doping policy should be replaced with a more efficient and practical strategy to identify and monitor abnormal and harmful deviations of the biochemical and haematological profiles.

  3. Graphene doping methods and device applications.

    Science.gov (United States)

    Oh, Jong Sik; Kim, Kyong Nam; Yeom, Geun Young

    2014-02-01

    Graphene has recently been studied as a promising material to replace and enhance conventional electronic materials in various fields such as electronics, photovoltaics, sensors, etc. However, for the electronic applications of graphene prepared by various techniques such as chemical vapor deposition, chemical exfoliation, mechanical exfoliation, etc., critical limitations are found due to the defects in the graphene in addition to the absence of a semiconducting band gap. For that, many researchers have investigated the doped graphene which is effective to tailor its electronic property and chemical reactivity. This work presents a review of the various graphene doping methods and their device applications. As doping methods, direct synthesis method and post treatment method could be categorized. Because the latter case has been widely investigated and used in various electronic applications, we will focus on the post treatment method. Post treatment method could be further classified into wet and dry doping methods. In the case of wet doping, acid treatment, metal chloride, and organic material coating are the methods used to functionalize graphene by using dip-coating, spin coating, etc. Electron charge transfer achieved from graphene to dopants or from dopants to graphene makes p-type or n-type graphenes, respectively, with sheet resistance reduction effect. In the case of dry doping, it can be further categorized into electrostatic field method, evaporation method, thermal treatment method, plasma treatment method, etc. These doping techniques modify Fermi energy level of graphene and functionalize the property of graphene. Finally, some perspectives and device applications of doped graphene are also briefly discussed.

  4. Doping control in sport

    DEFF Research Database (Denmark)

    Overbye, Marie Birch

    2016-01-01

    Doping testing is a key component enforced by anti-doping authorities to detect and deter doping in sport. Policy is developed to protect athletes' right to participate in doping-free sport; and testing is a key tool to secure this right. Accordingly, athletes' responses to anti-doping efforts.......e., the efforts of stakeholders involved in testing) in their own sport both nationally and worldwide. Moreover, it seeks to identify whether specific factors such as previous experience of testing and perceived proximity of doping have an impact on athletes' perceptions of the testing system. The study comprises...... a web-based questionnaire (N = 645; response rate 43%) and uses qualitative findings to elaborate on and explain quantitative results. Results showed that two-thirds of the athletes reported the national testing programme in their sport to be appropriate. A majority of the athletes who had an opinion...

  5. Growth and characterization of pure and doped NLO L-arginine ...

    Indian Academy of Sciences (India)

    Administrator

    doped LAA were prepared by dissolving stoichiometric L-arginine. (AR grade) and acetic acid in double deionized water. The pure and doped LAA crystals were grown by slow evaporation technique at room temperature (30°C). The reaction that takes place between L-arginine and acetic acid in water medium is as follows:.

  6. Polarization induced doped transistor

    Science.gov (United States)

    Xing, Huili; Jena, Debdeep; Nomoto, Kazuki; Song, Bo; Zhu, Mingda; Hu, Zongyang

    2016-06-07

    A nitride-based field effect transistor (FET) comprises a compositionally graded and polarization induced doped p-layer underlying at least one gate contact and a compositionally graded and doped n-channel underlying a source contact. The n-channel is converted from the p-layer to the n-channel by ion implantation, a buffer underlies the doped p-layer and the n-channel, and a drain underlies the buffer.

  7. Oral tranexamic acid enhances the efficacy of low-fluence 1064-nm quality-switched neodymium-doped yttrium aluminum garnet laser treatment for melasma in Koreans: a randomized, prospective trial.

    Science.gov (United States)

    Shin, Jung U; Park, Jihun; Oh, Sang Ho; Lee, Ju Hee

    2013-03-01

    Tranexamic acid (TA) has recently gained in popularity in the treatment of pigmentary disorders. To evaluate the clinical efficacy and safety of oral TA combined with low-fluence 1064-nm quality-switched neodymium-doped yttrium aluminum garnet (QSNY) laser for the treatment of melasma. Forty-eight patients with melasma were enrolled in the study and subsequently divided into two groups: a combination group and a laser treatment group. All patients were treated with two sessions of low-fluence QSNY laser, and patients in the combination group took 8 weeks of oral TA. Two blinded dermatologists evaluated patients using the Modified Melasma Area and Severity Index (mMASI) and a clinical improvement scale. Mean mMASI score 4 weeks after the second treatment decreased significantly in both groups from base line. Based on overall clinical improvement, a greater number of patients scored as grade 3 and more in the combination group; no patients were scored as grade 4 in the laser-alone group. Oral TA may prove a safe and efficient treatment option for melasma in combination with low-fluence QSNY laser therapy. © 2012 by the American Society for Dermatologic Surgery, Inc. Published by Wiley Periodicals, Inc.

  8. Formation of indium-doped zinc oxide thin films using chemical spray techniques: The importance of acetic acid content in the aerosol solution and the substrate temperature for enhancing electrical transport

    Energy Technology Data Exchange (ETDEWEB)

    Castaneda, L. [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, 04510, D.F. (Mexico); Departamento de Fisica y Matematicas, Division de Estudios Disciplinares, Universidad Iberoamericana, Av. Prolongacion Paseo de la Reforma 880, Santa Fe 012100, D.F. (Mexico); Garcia-Valenzuela, A. [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apartado Postal 70-186, 04510, D.F. (Mexico); Zironi, E.P. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, 01000, D.F. (Mexico); Canetas-Ortega, J. [Instituto de Fisica, Universidad Nacional Autonoma de Mexico, Apartado Postal 20-364, 01000, D.F. (Mexico); Terrones, M. [Advanced Materials Department, IPICYT, Camino a la Presa San Jose 2055, Col. Lomas 4a. seccion, San Luis Potosi 78216 (Mexico) and Departamento de Fisica y Matematicas, Division de Estudios Disciplinares, Universidad Iberoamericana, Av. Prolongacion Paseo de la Reforma 880, Santa Fe 012100, D.F. (Mexico)]. E-mail: mterrones@ipicyt.edu.mx; Maldonado, A. [Depto. de Ing. Electrica, CINVESTAV IPN, SEES, Ap. Postal 14740, Mexico D.F. 07000 (Mexico)

    2006-05-01

    Indium-doped zinc oxide (ZnO:In) thin films were grown on glass substrates using the chemical spray technique. The effects of the acetic acid content in the starting solution (c {sub AA}), as well as the substrate temperature (T {sub S}), were studied. Our results demonstrate that when c {sub AA} is extremely low, the resistivity values of the zinc oxide (ZnO) thin films become relatively high (in the order of 4 x 10{sup -2} {omega} cm). When the c {sub AA} is increased at a fixed temperature, the resistivity of the films decreases, reaching values as low as 4 x 10{sup -3} {omega} cm for thin films deposited at 525 deg. C. The electron mobility could also increase to a maximum value of 10.5 cm{sup 2}/(V s) for films deposited at 500 deg. C. We also observed an enhancement in the electrical transport properties of the films by varying T {sub S}; the lowest resistivity values occurred in films deposited at T {sub S} between 475 and 525 deg. C. In addition, the relative intensity of the diffraction peaks associated with the crystallographic planes is strongly affected by the c {sub AA} concentration. X-ray diffraction studies reveal the polycrystalline nature of the films exhibiting a hexagonal wurtzite type, with a preferential orientation of the film depending on the acetic acid concentration. Film morphology was also affected by varying c {sub AA}, as grains with distinct geometrical shapes were observed. Finally, the optical transmittance of all these films was found to be higher than 85%.

  9. To dope or not to dope

    DEFF Research Database (Denmark)

    Overbye, Marie Birch; Knudsen, Mette Lykke; Pfister, Gertrud Ursula

    2013-01-01

    tAim: This study aims to examine the circumstances which athletes say affect their (hypothetical) consid-erations of whether to dope or not and explore the differences between athletes of different gender, ageand sport type.Methods: 645 elite athletes (mean age: 22.12; response rate: 43%) represe......tAim: This study aims to examine the circumstances which athletes say affect their (hypothetical) consid-erations of whether to dope or not and explore the differences between athletes of different gender, ageand sport type.Methods: 645 elite athletes (mean age: 22.12; response rate: 43......%) representing 40 sports completed aweb-based questionnaire. Participants were asked to imagine themselves in a situation in which theyhad to decide whether to dope or not to dope and then evaluate how different circumstances would affecttheir decisions.Results: Multiple circumstances had an effect on athletes......’ hypothetical decisions. The most effective deter-rents were related to legal and social sanctions, side-effects and moral considerations. Female athletesand younger athletes evaluated more reasons as deterrents than older, male athletes. When confrontedwith incentives to dope, the type of sport was often...

  10. [Doping and sports].

    Science.gov (United States)

    Lippi, G; Guidi, G

    1999-09-01

    Doping is widely known as the use of banned substances and practices by athletes in an attempt to improve sporting performances. The term doping likely derives from "dope", an ancient expression referred to a primitive alcoholic drink that was used as a stimulant in South African ceremonial dances; gradually, the term was extended and finally adopted his current significance. There are at least two essential reasons to support the fight against doping: the potential harmful effects on athletes and the depth corruption of the fair competition. An exhaustive list of banned substances and methods has been drawn by the International Olympic Committee and further accepted by other International Sport Authorities and Federations. This list, regularly updated, is basically divided into doping substances (stimulants, narcotic analgesics, anabolic agents, diuretics, peptide and glycoprotein hormones and analogues), doping methods (blood doping, pharmacological, chemical and physical manipulation) and drugs subjected to certain restrictions (alcohol, marijuana, local anesthetics, corticosteroids and beta-blockers). Although there might be some medical conditions, which could legitimate the need of these substances or methods, there is no place for their use in sport. Thus, an athlete's consume of any of these substances or methods will result in disqualification. Aim of the present review is to provide a synthetic description of both the desirable effects and the potentially harmful consequences of the use of some of the major doping substances and methods.

  11. Synthesis, characterization and fuel cell performance tests of boric acid and boron phosphate doped, sulphonated and phosphonated poly(vinyl alcohol) based composite membranes

    Science.gov (United States)

    Şahin, Alpay; Ar, İrfan

    2015-08-01

    The aim of this study is to synthesize a composite membrane having high proton conductivity, ion exchange capacity and chemical stability. In order to achieve this aim, poly(vinyl alcohol) (PVA) based composite membranes are synthesized by using classic sol-gel method. Boric acid (H3BO3) and boron phosphate (BPO4) are added to the membrane matrix in different ratios in order to enhance the membrane properties. Characterization tests, i.e; FT-IR analysis, mechanical strength tests, water hold-up capacities, swelling properties, ion exchange capacities, proton conductivities and fuel cell performance tests of synthesized membranes are carried out. As a result of performance experiments highest performance values are obtained for the membrane containing 15% boron phosphate at 0.6 V and 750 mA/cm2. Water hold-up capacity, swelling ratio, ion exchange capacity and proton conductivity of this membrane are found as 56%, 8%, 1.36 meq/g and 0.37 S/cm, respectively. These values are close to the values obtained ones for perfluorosulphonic acid membranes. Therefore this membrane can be regarded as a promising candidate for usage in fuel cells.

  12. Doping Level of Boron-Doped Diamond Electrodes Controls the Grafting Density of Functional Groups for DNA Assays.

    Science.gov (United States)

    Švorc, Ĺubomír; Jambrec, Daliborka; Vojs, Marian; Barwe, Stefan; Clausmeyer, Jan; Michniak, Pavol; Marton, Marián; Schuhmann, Wolfgang

    2015-09-02

    The impact of different doping levels of boron-doped diamond on the surface functionalization was investigated by means of electrochemical reduction of aryldiazonium salts. The grafting efficiency of 4-nitrophenyl groups increased with the boron levels (B/C ratio from 0 to 20,000 ppm). Controlled grafting of nitrophenyldiazonium was used to adjust the amount of immobilized single-stranded DNA strands at the surface and further on the hybridization yield in dependence on the boron doping level. The grafted nitro functions were electrochemically reduced to the amine moieties. Subsequent functionalization with a succinic acid introduced carboxyl groups for subsequent binding of an amino-terminated DNA probe. DNA hybridization significantly depends on the probe density which is in turn dependent on the boron doping level. The proposed approach opens new insights for the design and control of doped diamond surface functionalization for the construction of DNA hybridization assays.

  13. Proton-conducting membranes based on benzimidazole polymers for high-temperature PEM fuel cells. A chemical quest.

    Science.gov (United States)

    Asensio, Juan Antonio; Sánchez, Eduardo M; Gómez-Romero, Pedro

    2010-08-01

    The development of high-temperature PEM fuel cells (working at 150-200 degrees C) is pursued worldwide in order to solve some of the problems of current cells based on Nafion (CO tolerance, improved kinetics, water management, etc.). Polybenzimidazole membranes nanoimpregnated with phosphoric acid have been studied as electrolytes in PEMFCs for more than a decade. Commercially available polybenzimidazole (PBI) has been the most extensively studied and used for this application in membranes doped with all sorts of strong inorganic acids. In addition to this well-known polymer we also review here studies on ABPBI and other polybenzimidazole type membranes. More recently, several copolymers and related derivatives have attracted many researchers' attention, adding variety to the field. Furthermore, besides phosphoric acid, many other strong inorganic acids, as well as alkaline electrolytes have been used to impregnate benzimidazole membranes and are analyzed here. Finally, we also review different hybrid materials based on polybenzimidazoles and several inorganic proton conductors such as heteropoly acids, as well as sulfonated derivatives of the polymers, all of which contribute to a quickly-developing field with many blooming results and useful potential which are the subject of this critical review (317 references).

  14. Marijuana as doping in sports.

    Science.gov (United States)

    Campos, Daniel R; Yonamine, Mauricio; de Moraes Moreau, Regina L

    2003-01-01

    A high incidence of positive cases for cannabinoids, in analyses for doping control in sports, has been observed since the International Olympic Committee (IOC) included them in the 1989 list of prohibited drugs under the title of classes of prohibited substances in certain circumstances. Where the rules of sports federations so provide, tests are conducted for marijuana, hashish or any other cannabis product exposure by means of urinalysis of 11-nor-delta-9-tetrahydrocannabinol-9-carboxylic acid (carboxy-THC) the main metabolite of delta-9-tetrahydrocannabinol (THC). Concentrations >15 ng/mL (cut-off value) in confirmatory analytical procedures are considered doping. Cannabis is an illicit drug in several countries and has received much attention in the media for its potential therapeutic uses and the efforts to legalise its use. Studies have demonstrated that the use of cannabinoids can reduce anxiety, but it does not have ergogenic potential in sports activities. An increase in heart rate and blood pressure, decline of cardiac output and reduced psychomotor activity are some of the pharmacological effects of THC that will determine a decrease in athletic performance. An ergolytic activity of cannabis products has been observed in athletes of several different sport categories. In Brazil, analyses for doping control in sports, performed in our laboratories, have detected positive cases for carboxy-THC in urine samples of soccer, volleyball, cycling and other athletes. It is our intention to discuss in this article some points that may discourage individuals from using cannabis products during sports activities, even in the so-called permitted circumstances defined by the IOC and some sports federations.

  15. Aluminum Doped Parahydrogen Solids

    National Research Council Canada - National Science Library

    Fajardo, Mario

    2001-01-01

    ...) solids doped with large (- 1 %) concentrations of Al atoms. We incorporated into our apparatus a commercially available effusive Al atom source capable of delivering Al atom fluxes in excess of 10(exp 17...

  16. Synthesis, identification and study of electrical conductivity of the doped copolymer carbazole–phenol formaldehyde

    Directory of Open Access Journals (Sweden)

    Roza A. Salih

    2014-11-01

    The conductivity of copolymer carbazole–phenol formaldehyde doped with 4 (4-hydroxy-phenyl azo-benzene sulfonic acid (PABS, 2,5-dimethyl benzene sulfonic acid (PXSA and 4-hydroxy-m-benzene disulfonic acid (PDSA was studied as a function of weight of the dopant compounds; an increase of conductance of the copolymer by doping with PABS is noted; the conductance became equal to 0.000595 ohm−1 for 0.1 g higher conductance for the copolymer when it is doping with PABS.

  17. Effect of doping on photovoltaic characteristics of graphene

    Science.gov (United States)

    Deepshikha

    2016-12-01

    Chemical doping of CVD grown graphene by introducing PTSA ( n-type) and NBD ( p-type) dopants is explored. This type of doping is key building block for photovoltaic and optoelectronic devices. Doped graphene samples display (1) high transmittance in the visible and near-infrared spectrum and (2) tunable graphene sheet resistance and work function. Large area and uniform graphene films were produced by chemical vapor deposition on copper foils and transferred onto quartz as transparent substrates. For n doping, a solution of p-toluenesulfonic acid (PTSA) was first dropped and spin-coated on the graphene/quartz and then annealed at 100°C for 10 min to make graphene uniformly n-type. Subsequently, a bare graphene was transferred on another quartz substrate, a solution of 4-nitrobenzenediazonium tetrafluoroborate (NBD) was dropped and spin-coated on the surface of graphene and similarly annealed. As a result, the graphene was p and n doped on the different quartz substrates. Doped graphene samples were characterized by different techniques. Experimental results suggested that doped graphene sheets with tunable electrical resistance and high optical transparency can be incorporated into photovoltaics and optoelectronics devices.

  18. Polybenzimidazole-crosslinked poly(vinylbenzyl chloride) with quaternary 1,4-diazabicyclo (2.2.2) octane groups as high-performance anion exchange membrane for fuel cells

    Science.gov (United States)

    Lu, Wangting; Zhang, Geng; Li, Jin; Hao, Jinkai; Wei, Feng; Li, Wenhui; Zhang, Jiying; Shao, Zhi-Gang; Yi, Baolian

    2015-11-01

    Development of anion exchange membrane (AEM) with high conductivity, good dimensional stability, desirable toughness and long life-time simultaneously is still a challenge for the practical application of AEM fuel cells. Herein, a novel AEM (denoted as PBI-c-PVBC/OH) is fabricated by applying polybenzimidazole (PBI) and 1,4-diazabicyclo (2.2.2) octane (DABCO) as the macromolecular crosslinker and quaternizing reagent for poly(vinylbenzyl chloride) (PVBC), respectively. With the aid of crosslinking by PBI, PBI-c-PVBC/OH exhibits good flexibility and strength both in dry and water-saturated state. Moreover, high hydroxide conductivity (>25 mS cm-1 at room temperature) and low swelling ratio (∼13%) is obtained, especially the swelling ratio nearly does not increase with temperature. The membrane is also advanced for the superior chemical stability in alkaline environment due to the stable polymer backbone and ionic conductive group (only one nitrogen atom in a DABCO molecule is quaternized). Furthermore, a peak power density of 230 mW cm-2 at 50 °C is obtained on the H2/O2 fuel cell using PBI-c-PVBC/OH, and the membrane presents high durability both in the constant current and continuous open circuit voltage testing. Therefore, it is considered that the PBI crosslinking together with DABCO quaternization can be regarded as a promising strategy in the development of AEM for fuel cells.

  19. Sanctions for doping in sport

    Directory of Open Access Journals (Sweden)

    Mandarić Sanja

    2014-01-01

    Full Text Available Top-level sport imposes new and more demanding physical and psychological pressures, and the desire for competing, winning and selfassertion leads athletes into temptation to use prohibited substances in order to achieve the best possible results. Regardless of the fact that the adverse consequences of prohibited substances are well-known, prestige and the need to dominate sports arenas have led to their use in sports. Doping is one of the biggest issues in sport today, and the fight against it is a strategic objective on both global and national levels. World Anti-Doping Agency, the International Olympic Committee, international sports federations, national anti-doping agencies, national sports federations, as well as governments and their repressive apparatuses are all involved in the fight against doping in sport. This paper points to a different etymology and phenomenology of doping, the beginnings of doping in sport, sports doping scandals as well as the most important international instruments regulating this issue. Also, there is a special reference in this paper to the criminal and misdemeanor sanctions for doping in sport. In Serbia doping in sport is prohibited by the Law on Prevention of Doping in Sports which came into force in 2005 and which prescribes the measures and activities aimed at prevention of doping in sport. In this context, the law provides for the following three criminal offenses: use of doping substances, facilitating the use of doping substances, and unauthorized production and putting on traffic of doping substances. In addition, aiming at curbing the abuse of doping this law also provides for two violations. More frequent and repetitive doping scandals indicate that doping despite long-standing sanctions is still present in sports, which suggests that sanctions alone have not given satisfactory results so far.

  20. Thermal, FT–IR and SHG efficiency studies of L-arginine doped KDP ...

    Indian Academy of Sciences (India)

    Thermal, FT–IR and SHG efficiency studies of L-arginine doped KDP crystals ... In the present study, amino acid L-arginine was doped in KDP. ... Department of Physics, Saurashtra University, Rajkot 360 005, India; Institute of Diploma Studies, Nirma University of Science and Technology, S.G. Highway, Ahmedabad 384 ...

  1. Synthesis of H2SO4 doped polyaniline film by potentiometric method

    Indian Academy of Sciences (India)

    H2SO4 doped polyaniline films were synthesized in aqueous acidic media. The polyaniline film deposited on platinum electrode exhibits highest conductivity. The conductivity of each H2SO4 doped polyaniline sample was determined by the four-probe technique. The current–voltage curve exhibits that polyaniline sample ...

  2. Properties, degradation and high temperature fuel cell test of different types of PBI and PBI blend membranes

    DEFF Research Database (Denmark)

    Li, Qingfeng; Rudbeck, Hans Christian; Chromik, Andreas

    2010-01-01

    Polybenzimidazoles (PBIs) with synthetically modified structures and their blends with a partially fluorinated sulfonated aromatic polyether have been prepared and characterized for high temperature proton exchange membrane fuel cells. Significant improvement in the polymer chemical stability...... to further improve the polymer stability and assist maintaining the membrane integrity. Upon acid doping the membrane swelling was reduced for the modified PBI and their blend membranes, which, in turn, results in enhancement of the mechanical strength, proton conductivity and high temperature fuel cell...

  3. [Asthma drugs and doping].

    Science.gov (United States)

    Pillard, F; Rolland, Y; Rivière, D

    1999-11-01

    Some drugs regularly used in the treatment of asthma (beta-agonists and corticosteroids) are registered on the list of drugs forbidden in sport, because they have a doping action. To avoid penalizing asthmatic sportsmen, some beta-agonists (Salbutamol, Salmeterol, Terbutaline) and corticosteroids are allowed only in inhaled form, with written notification from the prescribing physician, a pneumologist or the team doctor. Considering the increase of doping with increasing involvement of physicians, good and up to date notions about the current rules of prescription in asthmatic sportsmen are needed.

  4. Nitrogen-Doped Carbon Dots for "green" Quantum Dot Solar Cells.

    Science.gov (United States)

    Wang, Hao; Sun, Pengfei; Cong, Shan; Wu, Jiang; Gao, Lijun; Wang, Yun; Dai, Xiao; Yi, Qinghua; Zou, Guifu

    2016-12-01

    Considering the environment protection, "green" materials are increasingly explored for photovoltaics. Here, we developed a kind of quantum dots solar cell based on nitrogen-doped carbon dots. The nitrogen-doped carbon dots were prepared by direct pyrolysis of citric acid and ammonia. The nitrogen-doped carbon dots' excitonic absorption depends on the N-doping content in the carbon dots. The N-doping can be readily modified by the mass ratio of reactants. The constructed "green" nitrogen-doped carbon dots solar cell achieves the best power conversion efficiency of 0.79 % under AM 1.5 G one full sun illumination, which is the highest efficiency for carbon dot-based solar cells.

  5. Synthesis and characterization of bis(thiourea)zinc chloride doped with L-arginine

    Energy Technology Data Exchange (ETDEWEB)

    Moitra, Sweta [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Kar, Tanusree, E-mail: mstk@iacs.res.in [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India)

    2009-09-15

    Single crystals of bis(thiourea)zinc chloride (BTZC) doped with basic amino acid L-arginine were grown successfully by slow evaporation method at ambient temperature. The doped crystals are optically better and more transparent than the pure ones having wide transmission spectra lying between 280 and 2000 nm. The comparative study of solubility curve shows a slight reduction in the solubility of the doped crystals. There is a drastic change in morphology due to doping which is also reflected in the X-ray diffraction pattern. The Fourier transform infrared spectroscopy study confirms the incorporation of L-arginine into BTZC crystal, as there is a deepening of the absorption peak at around 3200 cm{sup -1}. The second harmonic generation efficiency of the pure and the doped samples are almost same, which is equivalent to potassium dihydrogen phosphate. The doped crystals are harder than the pure one.

  6. Exploring Knowledge, Attitudes and Abuse Concerning Doping in Sport among Syrian Pharmacy Students

    Directory of Open Access Journals (Sweden)

    Mazen El-Hammadi

    2013-09-01

    Full Text Available This study aimed to assess pharmacy students’ knowledge about doping substances used in sport, explore their attitudes toward doping and investigate their misuse of doping drugs. A questionnaire was developed and employed to collect data from bachelor of pharmacy (BPharm students at the International University for Science and Technology (IUST. Two-hundred and eighty students participated in this self-administrated, paper-based survey. Around 90% of the students did not appear to know that narcotics, β-blockers and diuretics were used in sport as doping agents. Additionally, proportions between 60% and 80% considered vitamins, energy drinks and amino acids as substances that possess performance-enhancing effects. The main reason for doping, based on students’ response, was to improve muscular body appearance. The vast majority of students agreed that pharmacists should play a major role in promoting awareness about risks of doping. While students showed negative attitudes toward doping, approximately 15% of them, primarily males, had already tried a doping drug or might do so in the future. More than 60% of the students believed that sports-mates and friends are the most influential in encouraging them to take a doping agent. The study highlights the need to provide pharmacy students with advanced theoretical background and practical training concerning doping. This can be achieved by adopting simple, but essential, changes to the current curricula.

  7. Photocatalysis with chromium-doped TiO2: Bulk and surface doping

    KAUST Repository

    Ould-Chikh, Samy

    2014-04-15

    The photocatalytic properties of TiO2 modified by chromium are usually found to depend strongly on the preparation method. To clarify this problem, two series of chromium-doped titania with a chromium content of up to 1.56 wt % have been prepared under hydrothermal conditions: the first series (Cr:TiO2) is intended to dope the bulk of TiO2, whereas the second series (Cr/TiO2) is intended to load the surface of TiO2 with Cr. The catalytic properties have been compared in the photocatalytic oxidation of formic acid. Characterization data provides evidence that in the Cr/TiO2 catalysts chromium is located on the surface of TiO2 as amorphous CrOOH clusters. In contrast, in the Cr:TiO 2 series, chromium is mostly dissolved in the titania lattice, although a minor part is still present on the surface. Photocatalytic tests show that both series of chromium-doped titania demonstrate visible-light-driven photo-oxidation activity. Surface-doped Cr/TiO2 solids appear to be more efficient photocatalysts than the bulk-doped Cr:TiO2 counterparts. It\\'s classified! The photocatalytic properties of TiO2 modified by chromium depend strongly on the preparation method. To clarify this problem, two types of modified titania are discussed: one with CrIII doped in the bulk and one with CrOOH clusters on the TiO2 surface (see picture). Both series show visible-light-driven photo-oxidation activity. However, surface modification appears to be a more efficient strategy. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Electrochemical sensing behaviour of Ni doped Fe{sub 3}O{sub 4} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Suresh, R.; Giribabu, K.; Manigandan, R.; Narayanan, V., E-mail: vnnara@yahoo.co.in [Department of Inorganic Chemistry, University of Madras, Guindy Campus, Chennai 600 025 (India); Vijayalakshmi, L. [Annai Veilankanni' s College for Women (Arts and Science), Saidapet, Chennai 600015 (India); Stephen, A. [Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600 025 (India)

    2014-01-28

    Ni doped Fe{sub 3}O{sub 4} nanoparticles were synthesized by simple hydrothermal method. The prepared nanomaterials were characterized by X-ray diffraction analysis, DRS-UV-Visible spectroscopy and field emission scanning electron microscopy. The XRD confirms the phase purity of the synthesized Ni doped Fe{sub 3}O{sub 4} nanoparticles. The optical property of Ni doped Fe{sub 3}O{sub 4} nanoparticles were studied by DRS UV-Visible analysis. The electrochemical sensing property of pure and Ni doped Fe{sub 3}O{sub 4} nanoparticles were examined using uric acid as an analyte. The obtained results indicated that the Ni doped Fe{sub 3}O{sub 4} nanoparticles exhibited higher electrocatalytic activity towards uric acid.

  9. doped stable clusters a

    Indian Academy of Sciences (India)

    ABHIJIT DUTTA

    2018-01-30

    ., showed that Ru-doped. Rh6 cluster is a better catalyst for the activation of methanol compared to pure Rh6. It may be noted that methanol activation occurs via O–H bond dissociation rather than C–H bond.25 Rhodium nano ...

  10. Doped barium titanate nanoparticles

    Indian Academy of Sciences (India)

    We have synthesized nickel (Ni) and iron (Fe) ion doped BaTiO3 nanoparticles through a chemical route using polyvinyl alcohol (PVA). The concentration of dopant varies from 0 to 2 mole% in the specimens. The results from X-ray diffractograms and transmission electron micrographs show that the particle diameters in the ...

  11. Doped zinc oxide microspheres

    Science.gov (United States)

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

    1993-01-01

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  12. BLOOD DOPING AND RISKS

    Directory of Open Access Journals (Sweden)

    Goran Vasić

    2015-05-01

    Full Text Available Doping is the way in which athletes misuse of chemicals and other types of medical interventions (eg, blood replacement, try to get ahead in the results of other athletes or their performance at the expense of their own health. The aim of this work is the analysis of blood doping and the display of negative consequences that this way of increasing capabilities brings. Method: The methodological work is done descriptively. Results: Even in 1972 at the Stockholm Institute for gymnastics and sport, first Dr. Bjorn Ekblom started having blood doping. Taken from the blood, athletes through centifuge separating red blood cells from blood plasma, which is after a month of storage in the fridge, every athlete back into the bloodstream. Tests aerobic capacity thereafter showed that the concerned athletes can run longer on average for 25% of the treadmill than before. Discussion: Blood doping carries with it serious risks, excessive amount of red cells “thickens the blood,” increased hematocrit, which reduces the heart’s ability to pump blood to the periphery. All this makes it difficult for blood to flow through blood vessels, and there is a great danger that comes to a halt in the circulation, which can cause cardiac arrest, stroke, pulmonary edema, and other complications that can be fatal.

  13. Synthesis of a novel nitrogen-doped carbon dot by microwave-assisted carbonization method and its applications as selective probes for optical pH (acidity) sensing in aqueous/nonaqueous media, determination of nitrate/nitrite, and optical recognition of NOX gas.

    Science.gov (United States)

    Doroodmand, Mohammad Mahdi; Askari, Mohsen

    2017-05-22

    A novel nitrogen-doped carbon dot (N-CD) was synthesized via carbonization of citric acid in the presence of triethylenetetramine as a nitrogen source. The average size of the N-doped CDs and also the quantum yield of the synthesized N-doped CDs were both estimated to be 9 ± 2 nm and 39.5%, respectively. The applications of the synthesized carbon nanostructure as a high quantum yield fluorescence probe were initially adopted in the fabrication of a novel optical pH (acidity) sensor in both aqueous and nonaqueous environments. Two optimum dynamic intervals were obtained with the ranges of1.5-5.0 and 7.0-10.0. for the fabricated pH sensor with a standard deviation of 0.09 pH (n = 4). The quantity of HClO4 inside acetic acid was determined as the degree of acidity with a linear range between 1.0 and 4.0%. Determination of nitrate (NO3(-)) and nitrite (NO2(-)) based on the fluorescence quenching of N-CDs was also evaluated in detail. The linear ranges for NO2(-) and NO3(-) species were estimated to be from 1 × 10(-7)to 7.5 × 10(-5) and from 2.5 × 10(-6) to 7.5 × 10(-4) mol L(-1), respectively with RSD of 3.69% (n = 5) for NO2(-) and 3.54% (n = 5) for NO3(-). The LODs (X+3Sb) for both NO2(-) and NO3(-) were estimated to be 2.5 × 10(-8) and 7.5 × 10(-7) mol L(-1), respectively. The synthesized N-CDs were also applicable for NOX recognition in the gaseous form at part per thousand (ppt) levels with linear ranges of 3.77-36.51 and 27.67-43.77 ppt, LOD (X+3Sb) of 1.41 ppt (n = 4) and RSD of 4.37% (n = 5). The reliability of these methods was also evaluated via the analyses of different forms of gaseous, water and rumen samples. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. BF3-doped polyaniline: A novel conducting polymer

    Indian Academy of Sciences (India)

    unique conducting state of this system, which is in distinct contrast with the conventional proton-doped polyaniline samples. Keywords. Conducting polymer; polyaniline; Lewis acid; conductivity. PACS Nos 73.61.Ph; 33.15.Kr. 1. Introduction. During the past two decades, both fundamental and applied research in conducting.

  15. Doping Induced Solubility Control

    Science.gov (United States)

    Jacobs, Ian Edward

    Polymeric semiconductors are promising class of materials, which combine many of the electrical properties of inorganic semiconductors with the mechanical flexibility and chemical processability of organic materials. Semiconducting polymers can be deposited from solution over large areas at low cost, and may find applications in displays, photovoltaics, and sensor arrays. Unfortunately, these materials are generally mutually soluble with other organics, preventing solution-based deposition of complex patterned structures using standard photolithographic techniques. Here, we present an entirely new method for patterning conductive polymers utilizing a change in polymer solubility upon p-type doping. Many polymer : molecular dopant systems, including the extensively studied system poly-(3-hexylthiophene) : 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (P3HT : F4TCNQ), are rendered insoluble in a wide range solvents by p-type doping at only a few mol%. By sequentially doping and dedoping films, polymer solubility can be switched on an off at will. We find that doped films can be easily prepared in a two-step process, by first coating the polymer (P3HT), then exposing the film to an orthogonal solvent containing the dopant (F4TCNQ). Dedoping is achieved by means of a chemical reaction that deactivates F4TCNQ, allowing it to be removed by an orthogonal solvent in a single step. This process allows for fully quantitative dedoping, in some cases leaving films with an even lower free carrier density than as cast films by removing intrinsic p-type defects. In addition, we have also identified a photochemical reaction between F4TCNQ and solvents such as tetrahydrofuran (THF), which similarly yields a non-doping product. By immersing films in THF and exposing them to light, this reaction allows for direct, optical patterning of P3HT films. Using laser scanning confocal microscopy (LSCM), we demonstrate direct write topographic patterning of arbitrary structures with in

  16. ERYTHROPOIETIN AS DOPING AGENT

    Directory of Open Access Journals (Sweden)

    Nina Đukanović

    2012-09-01

    Full Text Available Doping is the use of prohibited substances and/or methods that improve the abilities of athletes. Erythropoietin (EPO, the kidney hormone, belongs to a group of substances that are classified as blood doping, and it can be found on the list of banned substances from 1990. year. Its application leads to an increase in the number of red blood cells, which enables better supply of oxygen, and thus improve the aerobic performance of athletes. Because of that, EPO is very popular in sports where the endurance is predominantly required like a marathon, cycling, triathlon, nordic skiing. Erythropoietin can cause some adverse events, primarily to increase blood viscosity, which is associated with a higher risk of various thromboembolic complications. In detection of EPO use two groups of tests are available, through a urine sample (direct method and blood sample (indirect method.

  17. Doping and Public Health

    DEFF Research Database (Denmark)

    Christiansen, Ask Vest

    rad av världens främsta idrottsvetare och dopningsexperter hade mött upp för att presentera papers till en intresserad och engagerad publik. Temat för konferensen var "Doping and Public Health", och den aspekten behandlades också; dock tolkade flera presentatörer temat på sina egna vis, och hela...

  18. Associated Polymers, Solvents and Doping Agents to Make Polyaniline Electrospinnable

    Science.gov (United States)

    Bertea, A.; Manea, L. R.; Bertea, A.; Hristian, L.

    2017-06-01

    Polyaniline (PANI) is a conductive polymer that has both metal (electrical, electronic, optical and magnetic properties) and polymer characteristics (low density, low-cost and resistance to chemicals). Polyaniline becomes a conductor by treatment with a dopant that acts by extracting electrons (oxidation) or by inserting electrons (reduction). The reduced solubility of PANI in all common solvents restricts its capacity to be electrospun into uniform fibers. The present paper reviews the methods to increase the solubility of PANI by blending it with other polymers and doping it with organic acids, highlighting the best polymer/solvent couples and doping agents.

  19. Doped Chiral Polymer Metamaterials Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Doped Chiral Polymer Metamaterials (DCPM) with tunable resonance frequencies have been developed by adding plasmonic inclusions into chiral polymers with variable...

  20. N-Doped Carbon Xerogels as Pt Support for the Electro-Reduction of Oxygen

    Directory of Open Access Journals (Sweden)

    Cinthia Alegre

    2017-09-01

    Full Text Available Durability and limited catalytic activity are key impediments to the commercialization of polymer electrolyte fuel cells. Carbon materials employed as catalyst support can be doped with different heteroatoms, like nitrogen, to improve both catalytic activity and durability. Carbon xerogels are nanoporous carbons that can be easily synthesized in order to obtain N-doped materials. In the present work, we introduced melamine as a carbon xerogel precursor together with resorcinol for an effective in-situ N doping (3–4 wt % N. Pt nanoparticles were supported on nitrogen-doped carbon xerogels and their activity for the oxygen reduction reaction (ORR was evaluated in acid media along with their stability. Results provide new evidences of the type of N groups aiding the activity of Pt for the ORR and of a remarkable stability for N-doped carbon-supported Pt catalysts, providing appropriate physico-chemical features.

  1. co-doped zinc oxide

    Indian Academy of Sciences (India)

    and TEM analyses indicated the presence of nanocrystal- lites aggregated in different shape particles. The band gap decreases in the case of the doped ZnO samples. Regarding the doped samples, the highest average visible transmittance of 89% and the lowest resistivity of 6.7 × 10−3 cm. PL spectra of the nanopowder ...

  2. Fitness Doping and Body Management

    DEFF Research Database (Denmark)

    Thualagant, Nicole

    This PhD thesis examines in a first paper the conceptualization of fitness doping and its current limitations. Based on a review of studies on bodywork and fitness doping it is emphasised that the definition of doping does not provide insights into bodywork of both men and women. Moreover......, it is argued that the social and a cultural context are missing in the many epidemiological studies on the prevalence of doping. The second paper explores the difficulties of implementing an anti-doping policy, which was originally formulated in an elite sport context, in a fitness context and more......-based fitness centres. Based on a survey in ten Danish club-based fitness centres and on narratives from semi-structured interviews, it is highlighted that the objectives of bodywork differ according to the users’ age and gender. Two different ways of investing in the body are explored in the paper, namely...

  3. Role Models on Dope

    DEFF Research Database (Denmark)

    Christiansen, Ask Vest; Gleaves, John

    2014-01-01

    Compared to football-players cyclists are virtuous role models. Yes, Lance Armstrong, Michael Rasmussen and other riders have doped, and because of this they have received the predicate as the most immoral athletes in the sporting world. But if morality is not only a question of whether a person...... has enhanced his or hers performances by the use of various drugs (and lied about it), but also is about human beings’ relations and interactions, then cycling isn’t as depraved as we like to tell each other. Football is much worse....

  4. Doped semiconductor nanocrystal junctions

    Energy Technology Data Exchange (ETDEWEB)

    Borowik, Ł.; Mélin, T., E-mail: thierry.melin@isen.iemn.univ-lille1.fr [Institut d’Electronique, de Microélectronique et de Nanotechnologie, CNRS-UMR8520, Avenue Poincaré, F-59652 Villeneuve d’Ascq (France); Nguyen-Tran, T.; Roca i Cabarrocas, P. [Laboratoire de Physique des Interfaces et des Couches Minces, CNRS-UMR7647, Ecole Polytechnique, F-91128 Palaiseau (France)

    2013-11-28

    Semiconductor junctions are the basis of electronic and photovoltaic devices. Here, we investigate junctions formed from highly doped (N{sub D}≈10{sup 20}−10{sup 21}cm{sup −3}) silicon nanocrystals (NCs) in the 2–50 nm size range, using Kelvin probe force microscopy experiments with single charge sensitivity. We show that the charge transfer from doped NCs towards a two-dimensional layer experimentally follows a simple phenomenological law, corresponding to formation of an interface dipole linearly increasing with the NC diameter. This feature leads to analytically predictable junction properties down to quantum size regimes: NC depletion width independent of the NC size and varying as N{sub D}{sup −1/3}, and depleted charge linearly increasing with the NC diameter and varying as N{sub D}{sup 1/3}. We thus establish a “nanocrystal counterpart” of conventional semiconductor planar junctions, here however valid in regimes of strong electrostatic and quantum confinements.

  5. Superconducting doped topological materials

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, Satoshi, E-mail: sasaki@sanken.osaka-u.ac.jp [Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Mizushima, Takeshi, E-mail: mizushima@mp.es.osaka-u.ac.jp [Department of Materials Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Department of Physics, Okayama University, Okayama 700-8530 (Japan)

    2015-07-15

    Highlights: • Studies on both normal- and SC-state properties of doped topological materials. • Odd-parity pairing systems with the time-reversal-invariance. • Robust superconductivity in the presence of nonmagnetic impurity scattering. • We propose experiments to identify the existence of Majorana fermions in these SCs. - Abstract: Recently, the search for Majorana fermions (MFs) has become one of the most important and exciting issues in condensed matter physics since such an exotic quasiparticle is expected to potentially give rise to unprecedented quantum phenomena whose functional properties will be used to develop future quantum technology. Theoretically, the MFs may reside in various types of topological superconductor materials that is characterized by the topologically protected gapless surface state which are essentially an Andreev bound state. Superconducting doped topological insulators and topological crystalline insulators are promising candidates to harbor the MFs. In this review, we discuss recent progress and understanding on the research of MFs based on time-reversal-invariant superconducting topological materials to deepen our understanding and have a better outlook on both the search for and realization of MFs in these systems. We also discuss some advantages of these bulk systems to realize MFs including remarkable superconducting robustness against nonmagnetic impurities.

  6. Influence of iron doping on tetravalent nickel content in catalytic oxygen evolving films

    Energy Technology Data Exchange (ETDEWEB)

    Li, Nancy; Bediako, D. Kwabena; Hadt, Ryan G.; Hayes, Dugan; Kempa, Thomas J.; von Cube, Felix; Bell, David C.; Chen, Lin X.; Nocera, Daniel G.

    2017-01-30

    Iron doping of nickel oxide films results in enhanced activity for promoting the oxygen evolution reaction (OER). Whereas this enhanced activity has been ascribed to a unique iron site within the nickel oxide matrix, we show here that Fe doping influences the Ni valency. The percent of Fe3+ doping promotes the formation of formal Ni4+, which in turn directly correlates with an enhanced activity of the catalyst in promoting OER. The role of Fe3+ is consistent with its behavior as a superior Lewis acid.

  7. Synthesis of a novel nitrogen-doped carbon dot by microwave-assisted carbonization method and its applications as selective probes for optical pH (acidity) sensing in aqueous/nonaqueous media, determination of nitrate/nitrite, and optical recognition of NO{sub X} gas

    Energy Technology Data Exchange (ETDEWEB)

    Doroodmand, Mohammad Mahdi, E-mail: doroodmand@shirazu.ac.ir; Askari, Mohsen

    2017-05-22

    A novel nitrogen-doped carbon dot (N-CD) was synthesized via carbonization of citric acid in the presence of triethylenetetramine as a nitrogen source. The average size of the N-doped CDs and also the quantum yield of the synthesized N-doped CDs were both estimated to be 9 ± 2 nm and 39.5%, respectively. The applications of the synthesized carbon nanostructure as a high quantum yield fluorescence probe were initially adopted in the fabrication of a novel optical pH (acidity) sensor in both aqueous and nonaqueous environments. Two optimum dynamic intervals were obtained with the ranges of1.5–5.0 and 7.0–10.0. for the fabricated pH sensor with a standard deviation of 0.09 pH (n = 4). The quantity of HClO{sub 4} inside acetic acid was determined as the degree of acidity with a linear range between 1.0 and 4.0%. Determination of nitrate (NO{sub 3}{sup −}) and nitrite (NO{sub 2}{sup −}) based on the fluorescence quenching of N-CDs was also evaluated in detail. The linear ranges for NO{sub 2}{sup −} and NO{sub 3}{sup −} species were estimated to be from 1 × 10{sup −7}to 7.5 × 10{sup −5} and from 2.5 × 10{sup −6} to 7.5 × 10{sup −4} mol L{sup −1}, respectively with RSD of 3.69% (n = 5) for NO{sub 2}{sup −} and 3.54% (n = 5) for NO{sub 3}{sup −}. The LODs (X+3S{sub b}) for both NO{sub 2}{sup −} and NO{sub 3}{sup −} were estimated to be 2.5 × 10{sup −8} and 7.5 × 10{sup −7} mol L{sup −1}, respectively. The synthesized N-CDs were also applicable for NO{sub X} recognition in the gaseous form at part per thousand (ppt) levels with linear ranges of 3.77–36.51 and 27.67–43.77 ppt, LOD (X+3S{sub b}) of 1.41 ppt (n = 4) and RSD of 4.37% (n = 5). The reliability of these methods was also evaluated via the analyses of different forms of gaseous, water and rumen samples. - Highlights: • N-dots as Fluorescent Probe. • N-dots Synthesized by Microwave-Assisted Carbonization. • Determination of Nitrate

  8. Nitrogen-doped graphene: effect of graphite oxide precursors and nitrogen content on the electrochemical sensing properties.

    Science.gov (United States)

    Megawati, Monica; Chua, Chun Kiang; Sofer, Zdenek; Klímová, Kateřina; Pumera, Martin

    2017-06-21

    Graphene, produced via chemical methods, has been widely applied for electrochemical sensing due to its structural and electrochemical properties as well as its ease of production in large quantity. While nitrogen-doped graphenes are widely studied materials, the literature showing an effect of graphene oxide preparation methods on nitrogen quantity and chemical states as well as on defects and, in turn, on electrochemical sensing is non-existent. In this study, the properties of nitrogen-doped graphene materials, prepared via hydrothermal synthesis using graphite oxide produced by various classical methods using permanganate or chlorate oxidants Staudenmaier, Hummers, Hofmann and Brodie oxidation methods, were studied; the resulting nitrogen-doped graphene oxides were labeled as ST-GO, HU-GO, HO-GO and BR-GO, respectively. The electrochemical oxidation of biomolecules, such as ascorbic acid, uric acid, dopamine, nicotinamide adenine nucleotide and DNA free bases, was carried out using cyclic voltammetry and differential pulse voltammetry techniques. The nitrogen content in doped graphene oxides increased in the order ST-GO graphene followed this trend, as shown in the cyclic voltammograms. This is a very important finding that provides insight into the electrocatalytic effect of N-doped graphene. The nitrogen-doped graphene materials exhibited improved sensitivity over bare glassy carbon for ascorbic acid, uric acid and dopamine detection. These studies will enhance our understanding of the effects of graphite oxide precursors on the electrochemical sensing properties of nitrogen-doped graphene materials.

  9. Nanocrystal doped matrixes

    Science.gov (United States)

    Parce, J. Wallace; Bernatis, Paul; Dubrow, Robert; Freeman, William P.; Gamoras, Joel; Kan, Shihai; Meisel, Andreas; Qian, Baixin; Whiteford, Jeffery A.; Ziebarth, Jonathan

    2010-01-12

    Matrixes doped with semiconductor nanocrystals are provided. In certain embodiments, the semiconductor nanocrystals have a size and composition such that they absorb or emit light at particular wavelengths. The nanocrystals can comprise ligands that allow for mixing with various matrix materials, including polymers, such that a minimal portion of light is scattered by the matrixes. The matrixes of the present invention can also be utilized in refractive index matching applications. In other embodiments, semiconductor nanocrystals are embedded within matrixes to form a nanocrystal density gradient, thereby creating an effective refractive index gradient. The matrixes of the present invention can also be used as filters and antireflective coatings on optical devices and as down-converting layers. Processes for producing matrixes comprising semiconductor nanocrystals are also provided. Nanostructures having high quantum efficiency, small size, and/or a narrow size distribution are also described, as are methods of producing indium phosphide nanostructures and core-shell nanostructures with Group II-VI shells.

  10. Optimizing doped libraries by using genetic algorithms

    Science.gov (United States)

    Tomandl, Dirk; Schober, Andreas; Schwienhorst, Andreas

    1997-01-01

    The insertion of random sequences into protein-encoding genes in combination with biologicalselection techniques has become a valuable tool in the design of molecules that have usefuland possibly novel properties. By employing highly effective screening protocols, a functionaland unique structure that had not been anticipated can be distinguished among a hugecollection of inactive molecules that together represent all possible amino acid combinations.This technique is severely limited by its restriction to a library of manageable size. Oneapproach for limiting the size of a mutant library relies on `doping schemes', where subsetsof amino acids are generated that reveal only certain combinations of amino acids in a proteinsequence. Three mononucleotide mixtures for each codon concerned must be designed, suchthat the resulting codons that are assembled during chemical gene synthesis represent thedesired amino acid mixture on the level of the translated protein. In this paper we present adoping algorithm that `reverse translates' a desired mixture of certain amino acids into threemixtures of mononucleotides. The algorithm is designed to optimally bias these mixturestowards the codons of choice. This approach combines a genetic algorithm with localoptimization strategies based on the downhill simplex method. Disparate relativerepresentations of all amino acids (and stop codons) within a target set can be generated.Optional weighing factors are employed to emphasize the frequencies of certain amino acidsand their codon usage, and to compensate for reaction rates of different mononucleotidebuilding blocks (synthons) during chemical DNA synthesis. The effect of statistical errors thataccompany an experimental realization of calculated nucleotide mixtures on the generatedmixtures of amino acids is simulated. These simulations show that the robustness of differentoptima with respect to small deviations from calculated values depends on their concomitantfitness. Furthermore

  11. Facile hydrothermal preparation of recyclable S-doped graphene sponge for Cu{sup 2+} adsorption

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Lianqin; Yu, Baowei [College of Chemistry and Environment Protection Engineering, Southwest University for Nationalities, Chengdu 610041 (China); Xue, Fumin [Shandong Provincial Analysis and Tester Center, Shandong Academy of Science, Jinan 250014 (China); Xie, Jingru; Zhang, Xiaoliang; Wu, Ruihan; Wang, Ruijue; Hu, Zhiyan [College of Chemistry and Environment Protection Engineering, Southwest University for Nationalities, Chengdu 610041 (China); Yang, Sheng-Tao, E-mail: yangst@pku.edu.cn [College of Chemistry and Environment Protection Engineering, Southwest University for Nationalities, Chengdu 610041 (China); Luo, Jianbin, E-mail: luojb1971@163.com [College of Chemistry and Environment Protection Engineering, Southwest University for Nationalities, Chengdu 610041 (China)

    2015-04-09

    Graphical abstract: S-doped graphene sponge was prepared via hydrothermal treatment, where S-doped graphene sponge had an adsorption capacity of 228 mg/g for Cu{sup 2+}. - Highlights: • S-doped graphene sponge was prepared by hydrothermal treatment for heavy metal adsorption. • S-doped graphene sponge had a huge adsorption capacity for Cu{sup 2+}, which was 40 times higher than that of active carbon. • S-doped graphene sponge could be easily regenerated by washing with acidic thiourea. - Abstract: Graphene sponge (GS) has been widely employed for water purification, but adsorption capacity loss frequently occurs during the formation of spongy structure. In this study, we reported the hydrothermal preparation of S-doped GS for the removal of Cu{sup 2+} with a huge adsorption capacity of 228 mg/g, 40 times higher than that of active carbon. The adsorption isotherm could be well fitted into the Freundlich model with a K{sub F} value of 36.309 (L/mg){sup 1/n}. The equilibrium adsorption could be fully achieved in the first 5 min. In the thermodynamics study, the negative ΔG indicated that the adsorption was spontaneous and physisorption in nature. The positive ΔH implied that the adsorption was endothermic. The changes of both pH and ionic strength had no apparent influence on the adsorption. S-doped GS could be easily regenerated by washing with acidic thiourea. Moreover, S-doped GS could be used for the adsorption of other heavy metal ions, too. The implication to the applications of S-doped GS in water treatment is discussed.

  12. Borohydride electro-oxidation by Ag-doped lanthanum chromites

    Indian Academy of Sciences (India)

    The electrocatalytic activity of Ag-doped lanthanum chromites electrode materials viz., LaCr0.4Ag0.6O3 and LaCr0.7Ag0.3O3 prepared by decomposing the precursor complex is studied. Pure LaCrO3 is synthesized by combustion route using oxalic acid as a fuel. The decomposition behaviour of the assynthesized powder ...

  13. Epitaxial Silicon Doped With Antimony

    Science.gov (United States)

    Huffman, James E.; Halleck, Bradley L.

    1996-01-01

    High-purity epitaxial silicon doped with antimony made by chemical vapor deposition, using antimony pentachloride (SbCI5) as source of dopant and SiH4, SiCI2H2, or another conventional source of silicon. High purity achieved in layers of arbitrary thickness. Epitaxial silicon doped with antimony needed to fabricate impurity-band-conduction photodetectors operating at wavelengths from 2.5 to 40 micrometers.

  14. TOXICOLOGICAL ENDPOINTS OF DOPING SUBSTANCES

    OpenAIRE

    BASARAN, A. Ahmet

    2017-01-01

    Athletes and non athletes weighlifters have tried to gain an unfairadvantage through the use doping substances since ancient times. Dopingsubstances although enhance sports performance, represent a risk to the healthof individuals and violate the sprit of competition. The use of prohibitedperformance enhancing drugs (PED’s) or methods to improve results incompetitive sports is referred as doping. Among the PED’s used areandrogenic-anabolic steroids (AASs), diuretics and masking agents, narkot...

  15. Doped graphene as a superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Mousavi, Hamze, E-mail: hamze.mousavi@gmail.co [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of)

    2010-06-28

    We study s-wave superconductivity state in doped graphene within the extended attractive Hubbard model and BCS theory. We use the Green's function approach and coherent potential approximation. We obtain critical temperature of graphene, T{sub c}, as a function of the impurity concentration, c, as well as impurity strength, {delta}. The results show that when c and {delta}, are increased, T{sub c} remains finite and doped graphene can be a superconductor.

  16. Color stable manganese-doped phosphors

    Science.gov (United States)

    Lyons, Robert Joseph [Burnt Hills, NY; Setlur, Anant Achyut [Niskayuna, NY; Deshpande, Anirudha Rajendra [Twinsburg, OH; Grigorov, Ljudmil Slavchev [Sofia, BG

    2012-08-28

    A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

  17. Structural, optical, magnetic and photocatalytic properties of Co doped CuS diluted magnetic semiconductor nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sreelekha, N.; Subramanyam, K. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Department of Physics, Raghu Engineering College, Visakhapatnam, Andrapradesh 531162 (India); Amaranatha Reddy, D. [Department of Chemistry and Chemical Institute for Functional Materials, Pusan National University, Busan 609735 (Korea, Republic of); Murali, G. [Department of BIN Fusion Technology & Department of Polymer-Nano Science and Technology, Chonbuk National University, Jeonju, Jeonbuk (Korea, Republic of); Ramu, S. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Rahul Varma, K. [Department of Mechanical Engineering, University of California, Berkeley (United States); Vijayalakshmi, R.P., E-mail: vijayaraguru@gmail.com [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India)

    2016-08-15

    Highlights: • Cu{sub 1−x}Co{sub x}S nanoparticles were synthesized via chemical co-precipitation method. • Structural, band gap, magnetization and photocatalysis studies were carried out. • All the doped samples exhibited intrinsic room temperature ferromagnetism. • Effect of magnetic properties on photocatalytic activity was analyzed. • CuS:Co nanoparticles may find applications in photocatalytic and spintronic devices. - Abstract: Pristine and Co doped covellite CuS nanoparticles were synthesized in aqueous solution by facile chemical co-precipitation method with Ethylene Diamine Tetra Acetic Acid (EDTA) as a stabilizing agent. EDAX measurements confirmed the presence of Co in the CuS host lattice. Hexagonal crystal structure of pure and Co doped CuS nanoparticles were authenticated by XRD patterns. TEM images indicated that sphere-shape of nanoparticles through a size ranging from 5 to 8 nm. The optical absorption edge moved to higher energies with increase in Co concentration as indicated by UV–vis spectroscopy. Magnetic measurements revealed that bare CuS sample show sign of diamagnetic character where as in Co doped nanoparticles augmentation of room temperature ferromagnetism was observed with increasing doping precursor concentrations. Photocatalytic performance of the pure and Co doped CuS nanoparticles were assessed by evaluating the degradation rate of rhodamine B solution under sun light irradiation. The 5% Co doped CuS nanoparticles provide evidence for high-quality photocatalytic activity.

  18. XPS analysis of boron doped heterofullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Schnyder, B.; Koetz, R. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Muhr, H.J.; Nesper, R. [ETH Zurich, Zurich (Switzerland)

    1997-06-01

    Boron heterofullerenes were generated through arc-evaporation of doped graphite rods in a helium atmosphere. According to mass spectrometric analysis only mono-substituted fullerenes like C{sub 59}B, C{sub 69}B and higher homologues together with a large fraction of higher undoped fullerenes were extracted and enriched when pyridine was used as the solvent. XPS analysis of the extracts indicated the presence of two boron species with significantly different binding energies. One peak was assigned to borid acid. The second one corresponds to boron in the fullerene cage, which is mainly C{sub 59}B, according to the mass spectrum. This boron is in a somewhat higher oxidation state than that of ordinary boron-carbon compounds. The reported synthesis and extraction procedure opens a viable route for production of macroscopic amounts of these compounds. (author) 2 figs., 1 tab., 7 refs.

  19. Glycolic acid modulates the mechanical property and degradation of poly(glycerol, sebacate, glycolic acid).

    Science.gov (United States)

    Sun, Zhi-Jie; Wu, Lan; Huang, Wei; Chen, Chang; Chen, Yan; Lu, Xi-Li; Zhang, Xiao-Lan; Yang, Bao-Feng; Dong, De-Li

    2010-01-01

    The development of biodegradable materials with controllable degradation properties is beneficial for a variety of applications. Poly(glycerol-sebacate) (PGS) is a promising candidate of biomaterials; so we synthesize a series of poly(glycerol, sebacate, glycolic acid) (PGSG) with 1:2:0, 1:2:0.2, 1:2:0.4, 1:2:0.6, 1:2:1 mole ratio of glycerol, sebacate, and glycolic acid to elucidate the relation of doped glycolic acid to the degradation rate and mechanical properties. The microstructures of the polymers with different doping of glycolic acid were dissimilar. PGSG with glycolic acid in the ratio of 0.2 displayed an integral degree of ordering, different to those with glycolic acid in the ratio of 0, 0.4, 0.6, and 1, which showed mild phase separation structure. The number, DeltaH(m), and temperature of the PGSG melting peaks tended to decrease with the increasing ratio of doped glycolic acid. In vitro and in vivo degradation tests showed that the degradation rate of PGSG with glycolic acid in the ratio of 0.2 was slowest, but in the ratio range of 0, 0.4, and 0.6, the degradation rate increased with the increase of glycolic acid. All PGSG samples displayed good tissue response and anticoagulant effects. Our data suggest that doping glycolic acid can modulate the microstructure and degree of crosslinking of PGS, thereby control the degradation rate of PGS.

  20. Photocatalysis and hydrophilicity of doped TiO2 thin films.

    Science.gov (United States)

    Lee, Young Cheol; Hong, Young Pyo; Lee, Ha Yong; Kim, Hoon; Jung, Young Jin; Ko, Kyung Hyun; Jung, Hyun Seok; Hong, Kug Sun

    2003-11-01

    TiO(2) thin films were prepared using the dip-coating method with a polymeric sol including additives such as Al, W, and Al+W to examine two major properties: photocatalysis and hydrophilicity. W-doped films showed the best photocatalytic efficiency, while Al-doped film was poorer than undoped samples. However, good hydrophilicity in terms of saturation contact angle and surface conversion rate was found in Al- and (Al+W)-mixed-doped films. It was found that deep electron-hole traps and high surface acidity of W-doped TiO(2) thin film were the major factors in high photocatalytic efficiency. In addition, low surface acidities of Al- and (Al+W)-doped films provided better hydrophilicity than W-doped ones. However, the amount of [Ti(3+)] point defects on the surface was another major factor, probably the most important, in getting the best hydrophilicity. Conclusively, it seemed that many parts of the photocatalysis mechanism depend more on bulk-related properties than do those of hydrophilicity, which can be defined as an interfacial (surface) or near-surface-restricted process.

  1. Solution processed bulk heterojunction solar cells with molecularly doped active layers

    Energy Technology Data Exchange (ETDEWEB)

    Sio, Antonietta de; Tunc, Ali Veysel; Hauff, Elizabeth von; Parisi, Juergen [Energy and Semiconductor Research Laboratory, Institute of Physics, Carl von Ossietzky Universitaet Oldenburg, 26111 Oldenburg (Germany); Deschler, Felix; Como, Enrico da [Photonics and Optoelectronics Group, Department of Physics and CeNS, Ludwig-Maximilians-Universitaet Muenchen, 80799, Munich (Germany)

    2011-07-01

    We report on the improvement of the device performance of polymer:fullerene bulk heterojunction solar cells by molecularly doping the active layer. 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4-TCNQ) was used to p-dope the low bandgap polymer poly[2,6(4,4-bis-(2-ethylhexyl)-4H-cyclopenta[2,1-b:3,4-b0]-dithiophene)-alt-4,7-(2,1,3-benzothiadiazole)] (PCPDTBT) that was then blended with the soluble fullerene derivative [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Blends with different doping concentrations were investigated. We show how the short circuit current densities of the photovoltaic devices increase with the doping concentration as a result of an enhancement of the field effect mobilities.

  2. Cu-Doped-CdS/In-Doped-CdS Cosensitized Quantum Dot Solar Cells

    Directory of Open Access Journals (Sweden)

    Lin Li

    2014-01-01

    Full Text Available Cu-doped-CdS and In-doped-CdS cosensitized (Cu-doped-CdS/In-doped-CdS quantum dot solar cells (QDSCs are introduced here. Different cosensitized sequences, doping ratios, and the thickness (SILAR cycles of Cu-doped-CdS and In-doped-CdS are discussed. Compared with undoped CdS QDSCs, the short circuit current density, UV-Vis absorption spectra, IPCE (monochromatic incident photon-to-electron conversion, open circuit voltage, and so on are all improved. The photoelectric conversion efficiency has obviously improved from 0.71% to 1.28%.

  3. Doping a jeho etická dimenze

    OpenAIRE

    Vlk, Aleš

    2008-01-01

    Title of Dissertation: Doping and Its Ethical Dimension Aims: To work up general information about doping, doping resources and methods and their influence over the human organism, to think of the reasons, why people use forbidden supportive resources in sport, to judge the problem ofdoping in sport in term of ehtical and moral aspects, to evaluate the impacts of doping on trustworthiness ofthe athlete and the sport as a whole. Methods: The dissertation has a theoretic character and uses qual...

  4. [Xenon: From rare gaz to doping product].

    Science.gov (United States)

    Tassel, Camille; Le Daré, Brendan; Morel, Isabelle; Gicquel, Thomas

    2016-04-01

    Doping is defined as the use of processes or substances to artificially increase physical or mental performance. Xenon is a noble gas used as an anesthetic and recently as a doping agent. Xenon is neuroprotective as an antagonist of NMDA glutamate receptors. Xenon stimulates the synthesis of erythropoietin (EPO) by increase of hypoxia inducible factor (HIF). Xenon would be a new doping product, maintaining doping methods ahead of detection. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  5. Method for producing iron-based acid catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Farcasiu, M.; Kathrein, H.; Kaufman, P.B.; Diehl, J.R.

    1998-04-01

    A method for preparing an acid catalyst with a long shelf-life is described. Crystalline iron oxides are doped with lattice compatible metals which are heated with halogen compounds at elevated temperatures.

  6. Copper doped borate dosimeters revisited

    Energy Technology Data Exchange (ETDEWEB)

    Alajerami, Y.S.M. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Department of Medical Radiography, Al-Azhar University, Gaza Strip, Palestine (Country Unknown); Hashim, S., E-mail: suhairul@utm.my [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Oncology Treatment Centre, Sultan Ismail Hospital, 81100 Johor Bahru (Malaysia); Ghoshal, S.K. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Bradley, D.A. [Centre for Nuclear and Radiation Physics, Department of Physics, University of Surrey, Guildford GU2 7XH (United Kingdom); Department of Physics, Faculty of Science, University of Malaya, 50603 Kuala Lumpur (Malaysia); Mhareb, M. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); Saleh, M.A. [Department of Physics, Universiti Teknologi Malaysia, 81310 Skudai, Johor (Malaysia); National Atomic Energy Commission (NATEC), Sana' a (Yemen)

    2014-11-15

    We render a panoramic overview on copper (Cu) doped borate dosimeters. Preparing a dosimeter by mixing specific materials with precise weights and methods is a never-ending quest. The recommended composition is highly decisive for accurate estimation of the absorbed dose, prediction of the biological outcome, determination of the treatment dose for radiation therapy and facilitation of personal monitoring. Based on these principles, the proposed dosimeter must cover a series of dosimetric properties to realize the exact results and assessment. The doped borate dosimeters indeed demonstrate attractive thermoluminescence (TL) features. Several dedicated efforts are attempted to improve the luminescence properties by doping various transition metals or rare-earth elements. The Cu ion being one of the preferred activators shows excellent TL properties as revealed via detail comparison with other dosimeters. Two oxide states of Cu (Cu{sup +} and Cu{sup ++}) with reasonable atomic number allow easy interaction with boron network. Interestingly, the intrinsic luminescent centers of borate lattice are in cross linked with that of Cu{sup +} ions. Thus, the activation of borate dosimeter with Cu ions for the enhancement of the TL sensitivity is recognized. These dosimeters reveal similar glow curves as the standard TLD-100 (LiF:Mg,Ti) one irrespective of the use of modifiers and synthesis techniques. They display high sensitivity, low fading, dose response linearity over wide range and practical minimum detectable dose. Furthermore, the effective atomic number being the most beneficial aspect (equivalent to that of human tissue) of borate dosimeters do not show any change due to Cu ion activations. The past development, major challenges, excitement, applications, recent progress and the future promises of Cu doped borate TL dosimeters are highlighted. - Highlights: • The manuscript gives a panoramic overview on copper doped borate dosimeters. • Cu ions activated

  7. Extrinsic doping in silicon revisited

    KAUST Repository

    Schwingenschlögl, Udo

    2010-06-17

    Both n-type and p-type doping of silicon is at odds with the charge transfer predicted by Pauling electronegativities and can only be reconciled if we no longer regarding dopant species as isolated atoms but rather consider them as clusters consisting of the dopant and its four nearest neighbor silicon atoms. The process that gives rise to n-type and p-type effects is the charge redistribution that occurs between the dopant and its neighbors, as we illustrate here using electronic structure calculations. This view point is able to explain why conventional substitutional n-type doping of carbon has been so difficult.

  8. Electronegativity and doping in semiconductors

    KAUST Repository

    Schwingenschlögl, Udo

    2012-08-23

    Charge transfer predicted by standard models is at odds with Pauling’s electronegativities but can be reconciled by the introduction of a cluster formation model [Schwingenschlögl et al., Appl. Phys. Lett. 96, 242107 (2010)]. Using electronic structure calculations, we investigate p- and n-type doping in silicon and diamond in order to facilitate comparison as C has a higher electronegativity compared to Si. All doping conditions considered can be explained in the framework of the cluster formation model. The implications for codoping strategies and dopant-defect interactions are discussed.

  9. The Ethics of Doping and Anti-Doping

    DEFF Research Database (Denmark)

    Møller, Verner

    – is at heart nothing less than a battle to save sport from itself, located on the fault-line between the will to purity and the will to win. Drawing on extensive and detailed case studies of doping in sport, and using a highly original blend of conceptual ideas from philosophy and sociology, Møller strongly...

  10. Controlled doping by self-assembled dendrimer-like macromolecules

    Science.gov (United States)

    Wu, Haigang; Guan, Bin; Sun, Yingri; Zhu, Yiping; Dan, Yaping

    2017-02-01

    Doping via self-assembled macromolecules might offer a solution for developing single atom electronics by precisely placing individual dopants at arbitrary location to meet the requirement for circuit design. Here we synthesize dendrimer-like polyglycerol macromolecules with each carrying one phosphorus atom in the core. The macromolecules are immobilized by the coupling reagent onto silicon surfaces that are pre-modified with a monolayer of undecylenic acid. Nuclear magnetic resonance (NMR) and X-ray photoelectron spectroscopy (XPS) are employed to characterize the synthesized macromolecules and the modified silicon surfaces, respectively. After rapid thermal annealing, the phosphorus atoms carried by the macromolecules diffuse into the silicon substrate, forming dopants at a concentration of 1017 cm-3. Low-temperature Hall effect measurements reveal that the ionization process is rather complicated. Unlike the widely reported simple ionization of phosphorus dopants, nitrogen and carbon are also involved in the electronic activities in the monolayer doped silicon.

  11. Secondary doping in polyaniline layers coated on multi-walled carbon nanotubes

    Directory of Open Access Journals (Sweden)

    Zhou Yi

    2015-01-01

    Full Text Available HC1 doped coaxial polyaniline/multiwalled carbon nanotubes (MWCNTs nanocomposites were first prepared by in–situ chemical polymerization of aniline monomers in the presence of MWCNTs with less structural defects. P-toluene sulfonic acid (TSA and 5-sulfosalicylic acid dihydrate (SSA redoped PANI/MWCNT nanocomposites were achieved after the as-prepared nanocomposites were treated by ammonia respectively. The redoped nanocomposites were characterized by field emission scanning electron microscopy, transmission electron microscopy, fourier transform infrared spectroscopy, Raman, X–ray diffraction, thermogravimetric analysis and cyclic voltammetry, respectively. The results indicated that the thermal stability and electrochemical behaviour of TSA doped PANI/MWCNT nanocomposites were better than that of SSA doped PANI/MWCNT nanocomposites.

  12. Preparation of Mn doped CeO{sub 2} nanoparticles with enhanced ferromagnetism

    Energy Technology Data Exchange (ETDEWEB)

    Ravi, S., E-mail: sravi@mepcoeng.ac.in; Winfred Shashikanth, F.

    2017-06-15

    Spherical-like CeO{sub 2} and Mn-doped CeO{sub 2} using 6-aminohexanoic acid as surfactant exhibit enhanced ferromagnetism. The optical absorption spectra reveal a red shift with a band gap of 2.51 eV. The mechanics of ferromagnetism and the red shift were analyzed. These results provide a promising platform for developing a dilute magnetic semiconductor in spintronics. - Highlights: • Pure and Mn-doped CeO{sub 2} is prepared with aminohexanoic acid as capping. • They exhibit wide optical absorption with red-shift in their band gap. • Mn-doped CeO{sub 2} nanoparticle exhibit hysteresis at room temperature. • Results were promising to use in spintronics and opto-electronics field.

  13. Mg 2+-doped GaN nanoparticles as blue-light emitters: a method to avoid sintering at high temperatures.

    Science.gov (United States)

    Mahalingam, Venkataramanan; Sudarsan, Vasanthakumaran; Munusamy, Prabhakaran; van Veggel, Frank C J M; Wang, Rui; Steckl, Andrew J; Raudsepp, Mati

    2008-01-01

    Bright blue-light emission at 410 nm is observed from Mg(2+)-doped GaN nanoparticles prepared by the nitridation of Ga(2)MgO(4) nanoparticles at 950 degrees C. The sintering of these nanoparticles during high-temperature nitridation was prevented by mixing the Ga(2)MgO(4) precursor nanoparticles with La(2)O(3) as an inert matrix before the nitridation process. The Mg(2+)-doped GaN nanoparticles were isolated from the matrix by etching with 10 % nitric acid. The Mg(2+)-doped GaN nanoparticles were characterized by photoluminescence, atomic force microscopy, X-ray diffraction, and IR analyses.

  14. Impurity doping processes in silicon

    CERN Document Server

    Wang, FFY

    1981-01-01

    This book introduces to non-experts several important processes of impurity doping in silicon and goes on to discuss the methods of determination of the concentration of dopants in silicon. The conventional method used is the discussion process, but, since it has been sufficiently covered in many texts, this work describes the double-diffusion method.

  15. Steroid profiling in doping analysis

    NARCIS (Netherlands)

    Kerkhof, Daniël Henri van de

    2001-01-01

    Profiling androgens in urine samples is used in doping analysis for the detection of abused steroids of endogenous origin. These profiling techniques were originally developed for the analysis of testosterone, mostly by means of the ratio of testosterone to epitestosterone (T/E ratio). A study was

  16. GENES IN SPORT AND DOPING

    Science.gov (United States)

    Kaliszewski, P.; Majorczyk, E.; Zembroń-Łacny, A.

    2013-01-01

    Genes control biological processes such as muscle production of energy, mitochondria biogenesis, bone formation, erythropoiesis, angiogenesis, vasodilation, neurogenesis, etc. DNA profiling for athletes reveals genetic variations that may be associated with endurance ability, muscle performance and power exercise, tendon susceptibility to injuries and psychological aptitude. Already, over 200 genes relating to physical performance have been identified by several research groups. Athletes’ genotyping is developing as a tool for the formulation of personalized training and nutritional programmes to optimize sport training as well as for the prediction of exercise-related injuries. On the other hand, development of molecular technology and gene therapy creates a risk of non-therapeutic use of cells, genes and genetic elements to improve athletic performance. Therefore, the World Anti-Doping Agency decided to include prohibition of gene doping within their World Anti-Doping Code in 2003. In this review article, we will provide a current overview of genes for use in athletes’ genotyping and gene doping possibilities, including their development and detection techniques. PMID:24744482

  17. GENES IN SPORT AND DOPING

    Directory of Open Access Journals (Sweden)

    Andrzej Pokrywka

    2013-06-01

    Full Text Available Genes control biological processes such as muscle production of energy, mitochondria biogenesis, bone formation erythropoiesis, angiogenesis, vasodilation, neurogenesis, etc. DNA profiling for athletes reveals genetic variations that may be associated with endurance ability, muscle performance and power exercise, tendon susceptibility to injuries and psychological aptitude. Already, over 200 genes relating to physical performance have been identified by several research groups. Athletes’ genotyping is developing as a tool for the formulation of personalized training and nutritional programmes to optimize sport training as well as for the prediction of exercise-related injuries. On the other hand, development of molecular technology and gene therapy creates a risk of non-therapeutic use of cells, genes and genetic elements to improve athletic performance. Therefore, the World Anti-Doping Agency decided to include prohibition of gene doping within their World Anti-Doping Code in 2003. In this review article, we will provide a current overview of genes for use in athletes’ genotyping and gene doping possibilities, including their development and detection techniques.

  18. Doped to Rare Earth Ions

    African Journals Online (AJOL)

    In the present work, we are interested by studying the spectroscopic properties for optical applications, mainly laser amplification, of MF2 crystals, where M is an alkaline earth (Ba, Sr) or Cadmium (Cd) doped with rare earth ions (Tb3+, Er3+, Ho3+. So far, we present the absorption and emission properties and also the ...

  19. Physically Cross-linked Polymer Binder Induced by Reversible Acid-Base Interaction for High-Performance Silicon Composite Anodes.

    Science.gov (United States)

    Lim, Sanghyun; Chu, Hodong; Lee, Kukjoo; Yim, Taeeun; Kim, Young-Jun; Mun, Junyoung; Kim, Tae-Hyun

    2015-10-28

    Silicon is greatly promising for high-capacity anode materials in lithium-ion batteries (LIBs) due to their exceptionally high theoretical capacity. However, it has a big challenge of severe volume changes during charge and discharge, resulting in substantial deterioration of the electrode and restricting its practical application. This conflict requires a novel binder system enabling reliable cyclability to hold silicon particles without severe disintegration of the electrode. Here, a physically cross-linked polymer binder induced by reversible acid-base interaction is reported for high performance silicon-anodes. Chemical cross-linking of polymer binders, mainly based on acidic polymers including poly(acrylic acid) (PAA), have been suggested as effective ways to accommodate the volume expansion of Si-based electrodes. Unlike the common chemical cross-linking, which causes a gradual and nonreversible fracturing of the cross-linked network, a physically cross-linked binder based on PAA-PBI (poly(benzimidazole)) efficiently holds the Si particles even after the large volume changes due to its ability to reversibly reconstruct ionic bonds. The PBI-containing binder, PAA-PBI-2, exhibited large capacity (1376.7 mAh g(-1)), high Coulombic efficiency (99.1%) and excellent cyclability (751.0 mAh g(-1) after 100 cycles). This simple yet efficient method is promising to solve the failures relating with pulverization and isolation from the severe volume changes of the Si electrode, and advance the realization of high-capacity LIBs.

  20. Preparation and characterization of Ce-doped HfO{sub 2} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gálvez-Barboza, S. [Centro de Investigación en Química Aplicada, Departamento de Materiales Avanzados, Blvd. Enrique Reyna Hermosillo #140, C.P. 25294 Saltillo, Coahuila (Mexico); Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Industria Metalúrgica # 1062 Parque Industrial, C.P. 25900 Ramos Arizpe, Coahuila (Mexico); González, L.A. [Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, Av. Industria Metalúrgica # 1062 Parque Industrial, C.P. 25900 Ramos Arizpe, Coahuila (Mexico); Puente-Urbina, B.A.; Saucedo-Salazar, E.M. [Centro de Investigación en Química Aplicada, Departamento de Materiales Avanzados, Blvd. Enrique Reyna Hermosillo #140, C.P. 25294 Saltillo, Coahuila (Mexico); García-Cerda, L.A., E-mail: luis.garcia@ciqa.edu.mx [Centro de Investigación en Química Aplicada, Departamento de Materiales Avanzados, Blvd. Enrique Reyna Hermosillo #140, C.P. 25294 Saltillo, Coahuila (Mexico)

    2015-09-15

    Highlights: • Ce-doped HfO{sub 2} nanoparticles were prepared by a modified solgel method. • Ce-doped HfO{sub 2} nanoparticles have a semispherical shape with sizes between 6 and 11.5 nm. • The samples doped with 10% in weight of Ce directly crystallized in a cubic structure. • A quick, straightforward and effective route for the preparation of Ce-doped nanoparticles. - Abstract: A modified solgel method to synthesize Ce-doped HfO{sub 2} nanoparticles was carried out using a precursor material prepared with cerium nitrate, hafnium chloride, citric acid and ethylene glycol. The obtained precursor material was calcined at 500 and 700 °C for 2 h in air. The influence of the concentration of Ce and the calcination temperature was studied to observe the structural and morphological changes of the obtained materials. For the characterization, X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman scattering (RS) were employed. The XRD patterns shown that the Ce-doped HfO{sub 2} undergoes a structural transformation from monoclinic to cubic phase, which is significantly dependent on the Ce content and calcination temperature. TEM images have also confirmed the existence of semispherical nanoparticles with sizes between 6 and 11.5 nm.

  1. Hydrothermal Synthesis of Nitrogen-Doped Titanium Dioxide and Evaluation of Its Visible Light Photocatalytic Activity

    Directory of Open Access Journals (Sweden)

    Junjie Qian

    2012-01-01

    Full Text Available Nitrogen-doped titanium dioxide (N-doped TiO2 photocatalyst was synthesized from nanotube titanic acid (denoted as NTA; molecular formula H2Ti2O5·H2O precursor via a hydrothermal route in ammonia solution. As-synthesized N-doped TiO2 catalysts were characterized by means of X-ray diffraction, transmission electron microscopy, diffuse reflectance spectrometry, X-ray photoelectron spectroscopy, electron spin resonance spectrometry and Fourier transform infrared spectrometry. It was found that nanotube ammonium titanate (NAT was produced as an intermediate during the preparation of N-doped TiO2 from NTA, as evidenced by the N1s X-ray photoelectron spectroscopic peak of NH4 + at 401.7 eV. The catalyst showed much higher activities to the degradation of methylene blue and p-chlorophenol under visible light irradiation than Degussa P25. This could be attributed to the enhanced absorption of N-doped TiO2 in visible light region associated with the formation of single-electron-trapped oxygen vacancies and the inhibition of recombination of photo-generated electron-hole pair by doped nitrogen.

  2. Formation mechanism and optimization of highly luminescent N-doped graphene quantum dots

    Science.gov (United States)

    Qu, Dan; Zheng, Min; Zhang, Ligong; Zhao, Haifeng; Xie, Zhigang; Jing, Xiabin; Haddad, Raid E.; Fan, Hongyou; Sun, Zaicheng

    2014-01-01

    Photoluminescent graphene quantum dots (GQDs) have received enormous attention because of their unique chemical, electronic and optical properties. Here a series of GQDs were synthesized under hydrothermal processes in order to investigate the formation process and optical properties of N-doped GQDs. Citric acid (CA) was used as a carbon precursor and self-assembled into sheet structure in a basic condition and formed N-free GQD graphite framework through intermolecular dehydrolysis reaction. N-doped GQDs were prepared using a series of N-containing bases such as urea. Detailed structural and property studies demonstrated the formation mechanism of N-doped GQDs for tunable optical emissions. Hydrothermal conditions promote formation of amide between –NH2 and –COOH with the presence of amine in the reaction. The intramoleculur dehydrolysis between neighbour amide and COOH groups led to formation of pyrrolic N in the graphene framework. Further, the pyrrolic N transformed to graphite N under hydrothermal conditions. N-doping results in a great improvement of PL quantum yield (QY) of GQDs. By optimized reaction conditions, the highest PL QY (94%) of N-doped GQDs was obtained using CA as a carbon source and ethylene diamine as a N source. The obtained N-doped GQDs exhibit an excitation-independent blue emission with single exponential lifetime decay. PMID:24938871

  3. Thermal, FT–IR and SHG efficiency studies of L-arginine doped KDP ...

    Indian Academy of Sciences (India)

    TECS

    NLO properties, the present communication is a part of the extensive studies being carried out on the effect of different amino acids doping on the properties of KDP. ..... single crystalline nature of the sample is the most ordered form of the sample and dehydration of the sample brings the disorder in the sample, therefore, the.

  4. Effects on the electro-mechanical properties of aniline-doped ...

    African Journals Online (AJOL)

    The effects of Electro-mechanical properties of doped polyester fabric with aniline were investigated. The effects of various concentrations on the electrical as well as mechanical were examined and the percolation threshold was established. Chemical polymerization of aniline on Polyester in hydrochloric acid using ...

  5. Optical phase-conjugation in erioglaucine dye-doped thin film

    Indian Academy of Sciences (India)

    Optical phase-conjugation (OPC) has been demonstrated in erioglaucine (acid blue 9) dye-doped gelatin films via continuous-wave degenerate four-wave mixing (DFWM) using a low-power He-Ne laser at 633 nm. DFWM and holographic processes are found to contribute to the observed phase-conjugate signal.

  6. Characterization and photocatalytic activity of boron-doped TiO2 thin ...

    Indian Academy of Sciences (India)

    Boron doped TiO2 thin films have been successfully deposited on glass substrate and silicon wafer at 30°C from an aqueous solution of ammonium hexa-fluoro titanate and boron trifluoride by liquid phase deposition technique. The boric acid was used as an – scavenger. The resultant films were characterized by XRD, ...

  7. Tin dioxide sol-gel derived films doped with platinum and antimony deposited on porous silicon

    NARCIS (Netherlands)

    Savaniu, C.; Arnautu, A.; Cobianu, C.; Craciun, G.; Flueraru, C.; Zaharescu, M.; Parlog, C.; Paszti, F.; van den Berg, Albert

    1999-01-01

    SnO2 sol-gel derived thin films doped simultaneously with Pt and Sb are obtained and reported for the first time. The Sn sources were tin(IV) ethoxide or tin(II) ethylhexanoate, while hexachloroplatinic acid (H2PtCl6) and antimony chloride (SbCl3) were used as platinum and antimony sources,

  8. Doping kinetics of organic semiconductors investigated by field-effect transistors

    NARCIS (Netherlands)

    Maddalena, F.; Meijer, E.J.; Asadi, K.; Leeuw, D.M. de; Blom, P.W.M.

    2010-01-01

    The kinetics of acid doping of the semiconductor regioregular poly-3-hexylthiophene with vaporized chlorosilane have been investigated using field-effect transistors. The dopant density has been derived as a function of temperature and exposure time from the shift in the pinch-off voltage, being the

  9. Nb-doped TiO2 thin films as photocatalytic materials

    Indian Academy of Sciences (India)

    Amorphous undoped and Nb-doped films were obtained by the spin coating method. The films have a compact structure, as revealed by scanning electron microscopy, and are very thin, with thickness values under 100 nm. The photocatalytic activity of the films was evaluated by observing the decomposition of an oleic acid ...

  10. Striking the Right Balance : Effectiveness of Anti-Doping Policies

    NARCIS (Netherlands)

    de Hon, O.M.

    2016-01-01

    Doping, and anti-doping, is in the news on a continuous basis. At the core of these stories and discussions is the question how effective anti-doping policies are to curb the use of doping in sports. Anti-doping policies are based on ethical values, a juridical framework, laboratory analyses,

  11. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, S A; Baumann, T F; Kong, J; Satcher, J H; Dresselhaus, M S

    2007-02-15

    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  12. Superior lithium adsorption and required magnetic separation behavior of iron-doped lithium ion-sieves

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shulei; Zheng, Shili; Wang, Zheming; Cui, Wenwen; Zhang, Hailin; Yang, Liangrong; Zhang, Yi; Li, Ping

    2018-01-01

    The recent research on adsorption-based lithium recovery from lithium-containing solutions has been centred on adsorption capacity and separation of lithium ion-sieves powder from solutions. Herein, an effective iron-doped lithium titanium oxide (Fe-doped Li2TiO3) was synthesized by Fe-doping via solid state reactions followed by acid treatment to form iron-doped lithium ion-sieves (Fe/Ti-x(H)). The resulting solid powder displays both superior adsorption capacity of lithium and high separation efficiency of the adsorbent from the solutions. SEM imaging and BET surface area measurement results showed that at Fe doping levels x0.15, Fe-doping led to grain shrinkage as compared to Li2TiO3 and at the same time the BET surface area increased. The Fe/Ti-0.15(H) exhibited saturated magnetization values of 13.76 emu g-1, allowing effective separation of the material from solid suspensions through the use of a magnet. Consecutive magnetic separation results suggested that the Fe/Ti-0.15(H) powders could be applied at large-scale and continuously removed from LiOH solutions with separation efficiency of 96% or better. Lithium adsorption studies indicated that the equilibrium adsorption capacity of Fe/Ti-0.15(H) in LiOH 2 solutions (1.8 g L-1 Li, pH 12) reached 53.3 mg g-1 within 24 h, which was higher than that of pristine Li2TiO3 (50.5 mg g-1) without Fe doping. Competitive adsorption and regeneration results indicated that the Fe/Ti-0.15(H) possessed a high selectivity for Li with facile regeneration. Therefore, it could be expected that the iron-doped lithium ion-sieves have practical applicability potential for large scale lithium extraction and recovery from lithium-bearing solutions.

  13. Iron-Doped Carbon Aerogels: Novel Porous Substrates for Direct Growth of Carbon Nanotubes

    Science.gov (United States)

    Steiner, S. A.; Baumann, T. F.; Kong, J.; Satcher, J. H.; Dresselhaus, M. S.

    2007-02-20

    We present the synthesis and characterization of Fe-doped carbon aerogels (CAs) and demonstrate the ability to grow carbon nanotubes directly on monoliths of these materials to afford novel carbon aerogel-carbon nanotube composites. Preparation of the Fe-doped CAs begins with the sol-gel polymerization of the potassium salt of 2,4-dihydroxybenzoic acid with formaldehyde, affording K{sup +}-doped gels that can then be converted to Fe{sup 2+}- or Fe{sup 3+}-doped gels through an ion exchange process, dried with supercritical CO{sub 2} and subsequently carbonized under an inert atmosphere. Analysis of the Fe-doped CAs by TEM, XRD and XPS revealed that the doped iron species are reduced during carbonization to form metallic iron and iron carbide nanoparticles. The sizes and chemical composition of the reduced Fe species were related to pyrolysis temperature as well as the type of iron salt used in the ion exchange process. Raman spectroscopy and XRD analysis further reveal that, despite the presence of the Fe species, the CA framework is not significantly graphitized during pyrolysis. The Fe-doped CAs were subsequently placed in a thermal CVD reactor and exposed to a mixture of CH{sub 4} (1000 sccm), H{sub 2} (500 sccm), and C{sub 2}H{sub 4} (20 sccm) at temperatures ranging from 600 to 800 C for 10 minutes, resulting in direct growth of carbon nanotubes on the aerogel monoliths. Carbon nanotubes grown by this method appear to be multiwalled ({approx}25 nm in diameter and up to 4 mm long) and grow through a tip-growth mechanism that pushes catalytic iron particles out of the aerogel framework. The highest yield of CNTs were grown on Fe-doped CAs pyrolyzed at 800 C treated at CVD temperatures of 700 C.

  14. N,S,P Co-Doped Carbon Nanodot Fabricated from Waste Microorganism and Its Application for Label-Free Recognition of Manganese(VII) and l-Ascorbic Acid and AND Logic Gate Operation.

    Science.gov (United States)

    Gong, Xiaojuan; Li, Zengbo; Hu, Qin; Zhou, Ruixin; Shuang, Shaomin; Dong, Chuan

    2017-11-08

    A novel fluorescent probe based on N,S,P codoped carbon nanodots (N,S,P-CNDSac) is very simple and quickly fabricated by a one-step hydrothermal pyrolysis of Saccharomyces cerevisiae and utilized for label-free and "on-off-on" sequential detection of manganese(VII) and l-ascorbic acid (l-AA). The fluorescence of N,S,P-CNDSac can be effectively quenched by Mn(VII) based on an inner filter effect (IFE) and recovered upon the addition of l-AA due to the easy conversion of Mn(VII) to reduced states (i.e., Mn(IV), Mn(II), and Mn(0)) by l-AA. This probe exhibited favorable selectivity and sensitivity toward Mn(VII) and l-AA with detection limits of 50 nmol/L and 1.2 μmol/L, respectively. Simultaneously, an "AND" logic gate based on the as-fabricated N,S,P-CNDSac has been constructed. Also, the as-proposed fluorescent probe was extended to detect Mn(VII) and l-AA in biosystems. Furthermore, the as-constructed fluorescent probe system was successfully applied to the analyses of Mn(VII) in tap water, Fenhe River water, and medicinal herb samples with satisfactory results. The proposed method is simple and easily accessible, demonstrating the great potential of N,S,P-CNDSac in biosensing, disease diagnosis, cellular labeling, and environmental monitoring.

  15. All-polymer solar cells with bulk heterojunction nanolayers of chemically doped electron-donating and electron-accepting polymers.

    Science.gov (United States)

    Nam, Sungho; Shin, Minjung; Park, Soohyeong; Lee, Sooyong; Kim, Hwajeong; Kim, Youngkyoo

    2012-11-21

    We report the improved performance of all-polymer solar cells with bulk heterojunction nanolayers of an electron-donating polymer (poly(3-hexylthiophene) (P3HT)) and an electron-accepting polymer (poly(9,9-dioctylfluorene-co-benzothiadiazole) (F8BT)), which were both doped with 4-ethylbenzenesulfonic acid (EBSA). To choose the doping ratio of P3HT for all-polymer solar cells, various EBSA doping ratios (0, 1, 3, 5, 10, 20 wt%) were tested by employing optical absorption spectroscopy, photoluminescence spectroscopy, photoelectron yield spectroscopy, and space-charge-limited current (SCLC) mobility measurement. The doping reaction of P3HT with EBSA was followed by observing the colour change in solutions. The final doping ratio for P3HT was chosen as 1 wt% from the best hole mobility measured in the thickness direction, while that for F8BT was fixed as 10 wt% (F8BT-EBSA). The polymer:polymer solar cells with bulk heterojunction nanolayers of P3HT-EBSA (EBSA-doped P3HT) and F8BT-EBSA (EBSA-doped F8BT) showed greatly improved short circuit current density (J(SC)) and open circuit voltage (V(OC)), compared to the undoped solar cells. As a result, the power conversion efficiency (PCE) was enhanced by ca. 300% for the 6 : 4 (P3HT-EBSA : F8BT-EBSA) composition and ca. 400% for the 8 : 2 composition. The synchrotron-radiation grazing incidence angle X-ray diffraction (GIXD) measurement revealed that the crystallinity of the doped nanolayers significantly increased by EBSA doping owing to the formation of advanced phase segregation morphology, as supported by the surface morphology change measured by atomic force microscopy. Thus the improved PCE can be attributed to the enhanced charge transport by the formation of permanent charges and better charge percolation paths by EBSA doping.

  16. Doped Chiral Polymer Metamaterials

    Science.gov (United States)

    Park, Cheol (Inventor); Kang, Jin Ho (Inventor); Gordon, Keith L. (Inventor); Sauti, Godfrey (Inventor); Lowther, Sharon E. (Inventor); Bryant, Robert G. (Inventor)

    2017-01-01

    Some implementations provide a composite material that includes a first material and a second material. In some implementations, the composite material is a metamaterial. The first material includes a chiral polymer (e.g., crystalline chiral helical polymer, poly-.gamma.-benzyl-L-glutamate (PBLG), poly-L-lactic acid (PLA), polypeptide, and/or polyacetylene). The second material is within the chiral polymer. The first material and the second material are configured to provide an effective index of refraction value for the composite material of 1 or less. In some implementations, the effective index of refraction value for the composite material is negative. In some implementations, the effective index of refraction value for the composite material of 1 or less is at least in a wavelength of one of at least a visible spectrum, an infrared spectrum, a microwave spectrum, and/or an ultraviolet spectrum.

  17. Enhancing blue luminescence from Ce-doped ZnO nanophosphor by Li doping

    National Research Council Canada - National Science Library

    Shi, Qiang; Wang, Changzheng; Li, Shuhong; Wang, Qingru; Zhang, Bingyuan; Wang, Wenjun; Zhang, Junying; Zhu, Hailing

    2014-01-01

    .... The effects of the additional doping with Li ions on the crystal structure, particle morphology, and luminescence properties of Ce-doped ZnO were investigated by X-ray diffraction, scanning electron...

  18. Effect of reaction temperature on structure and fluorescence properties of nitrogen-doped carbon dots

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yi [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Chemistry and Chemical Engineering, Lyuliang University, Lyuliang 033001 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Wang, Yaling [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Feng, Xiaoting [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China); Zhang, Feng [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Yang, Yongzhen, E-mail: yyztyut@126.com [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); Research Center on Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Xuguang, E-mail: liuxuguang@tyut.edu.cn [Key Laboratory of Interface Science and Engineering in Advanced Materials (Taiyuan University of Technology), Ministry of Education, Taiyuan 030024 (China); College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024 (China)

    2016-11-30

    Highlights: • Nitrogen-doped carbon dots (NCDs) from ammonia solution and citric acid were synthesized at different temperatures. • Quantum yield (QY) of NCDs depends largely on the amount of fluorescent polymer chains (FPC), more FPC gives higher QY. • The law of QY of NCDs first increase and then decrease with the reaction temperature increased is found and explained. • Nitrogen doping plays significant role in getting increased UV–vis absorption and QY. - Abstract: To investigate the effect of reaction temperature and nitrogen doping on the structure and fluorescence properties of carbon dots (CDs), six kinds of nitrogen-doped CDs (NCDs) were synthesized at reaction temperatures of 120, 140, 160, 180, 200 and 220 °C, separately, by using citric acid as carbon source and ammonia solution as nitrogen source. Nitrogen-free CDs (N-free CDs-180) was also prepared at 180 °C by using citric acid as the only carbon source for comparison. Results show that reaction temperature has obvious effect on carbonization degree, quantum yield (QY), ultraviolet-visible (UV–vis) absorption and photoluminescence (PL) spectra but less effect on functional groups, nitrogen doping degree and fluorescence lifetime of NCDs. Compared with N-free CDs-180, NCDs-180 possesses enchanced QY and longer fluorescence lifetime. Doping nitrogen has obvious effect on UV–vis absorption and PL spectra but less effect on particles sizes and carbonization degree. The formation mechanism of NCDs is explored: QY of NCDs depends largely on the number of fluorescent polymer chains (FPC), the competition between FPC formation on the surface of NCDs and carbon core growth leads to the change in number of FPC, and consequently to the NCDs with highest QY at appropriate hydrothermal temperature.

  19. DFT study of Al doped armchair SWCNTs

    Energy Technology Data Exchange (ETDEWEB)

    Dhiman, Shobhna, E-mail: s-dhiman@hotmail.com [Department of Applied Science, PEC, University of Technology, Chandigarh -160012 (India); Rani, Anita [Guru Nanak College for Girls, Sri Muktsar Sahib, Punjab-152026 (India); Kumar, Ranjan; Dharamvir, Keya [Department of Physics, Panjab University, Chandigarh-160014 (India)

    2016-05-23

    Electronic properties of endohedrally doped armchair single-walled carbon nanotubes (SWCNTs) with a chain of six Al atoms have been studied using ab-initio density functional theory. We investigate the binding energy/atom, ionization potential, electron Affinity and Homo-Lumo gap of doped armchair SWNTs from (4,4) to (6,6) with two ends open. BE/dopant atom and ionization potential is maximum for (6, 6) doped armchair carbon nanotube; suggest that it is more stable than (4, 4) and (5, 5) doped tubes. HOMO - LUMO gap of Al doped arm chair carbon nanotubes decreases linearly with the increase in diameter of the tube. This shows that confinement induce a strong effect on electronic properties of doped tubes. These combined systems can be used for future nano electronics. The ab–initio calculations were performed with SIESTA code using generalized gradient approximation (GGA).

  20. Characterization of patterns of Localized Doping Using Stamping technique for Selective n-Emitter Solar Cell Structure

    Science.gov (United States)

    Mangkornkaew, A.; Fangsuwannarak, T.

    2017-10-01

    In the present, a novel cost-effective process scheme for single step selective emitter diffusion was implemented. It is based on the fabrication of acid-resist pattern using a stamping technique with collaboration of a spin on dopant (SOD) and chemical etched-back emitter methods. The SOD diffusion process provided heavily doping n-emitter. Acid-resist pattern without exploitation of a complex method as a photolithography, was stamped as a metal contact pattern for prevention of a localized heavy-dope region from etching back. Phosphorus doping profiles were controlled by etching back time to provide the formation of n-type selective emitter. Sheet resistance is tunable from 10 to 180 Ohm/Sq on localized n-layer. After removal of the patterned acid-resist, the selective n-emitter solar cell structure was obtained under one-step diffusion to achieve a better blue-light response and low contact resistance.

  1. Main modern problems of doping in sport

    Directory of Open Access Journals (Sweden)

    Rudenko V.P.

    2014-04-01

    Full Text Available Purpose : to identify and substantiate medico-biological, psychological and social problems of doping in sport. Material: Theoretical study is based on analysis of more than 50 scientific and methodical literatures. Results : it was shown that doping is one of the serious problems of modern sport and society in general. Defines important questions regarding anti-doping rules and the anti-doping control in sport. Installed the use of performance enhancing drugs in professional sports for children and youth. Given the promising solutions to the problems of doping in Ukraine. Conclusions: Among the problems of modern sport is becoming increasingly important issue of doping. It is an extremely complex because it involves the interrelated medical, legal, political, moral, organizational, social and pedagogical aspects. Socio-pedagogical factors of anti-doping policy in sports scientists comprehensively still not addressed. Certain aspects of anti-doping policy presented in scientific papers, which can be divided into two groups. The first group of papers is devoted to doping in sport as a social event. The second group of papers devoted to the problems of doping control. Today there is a need and objective preconditions for the development and adoption of a General concept, which would be generalized numerical amount of data received and served as a basis for developing an effective anti-doping control at the expense of improvement of legislative and normative-legal base and infrastructure of the anti-doping policy in Ukraine, which should be brought in line with modern international standards.

  2. Crosslinking of polybenzimidazolemembranes by divinylsulfone post-treatment for high-temperature proton exchange membrane fuel cell applications

    DEFF Research Database (Denmark)

    Aili, David; Li, Qingfeng; Christensen, Erik

    2011-01-01

    Phosphoric acid-doped polybenzimidazole (PBI) has been suggested as a promising electrolyte for proton exchangemembrane fuel cells operating at temperatures up to 200 ◦C. This paper describes the development of a crosslinking procedure for PBI membranes by post-treatment with divinylsulfone....... The crosslinking chemistry was studied and optimized on a low-molecularweight model system and the results were used to optimize the crosslinking conditions of PBI membranes. The crosslinked membraneswere characterized with respect to chemical and physiochemical properties, showing improved mechanical strength...

  3. Method of operating a direct dme fuel cell system

    DEFF Research Database (Denmark)

    2011-01-01

    The present invention relates to a method of operating a fuel cell system comprising one or more fuel cells with a proton exchange membrane, wherein the membrane is composed of a polymeric material comprising acid-doped polybenzimidazole (PBI). The method comprises adjusting the operating...... temperature of the fuel cell to between 120 and 250 degrees C, supplying an oxidant stream to the cathode, and supplying a humidified fuel stream to the anode, said fuel stream comprising dimethyl ether, wherein dimethyl ether is directly oxidised at the anode....

  4. Oxygen reduction on carbon supported platinum catalysts in high temperature polymer electrolytes

    DEFF Research Database (Denmark)

    Qingfeng, Li; Hjuler, Hans Aage; Bjerrum, Niels

    2000-01-01

    Oxygen reduction on carbon supported platinum catalysts has been investigated in H3PO4, H3PO4-doped Nafion and polybenzimidazole (PBI) polymer electrolytes in a temperature range up to 190 degrees C. Compared with pure H3PO4, the combination of H3PO4 and polymer electrolytes can significantly...... improve the oxygen reduction kinetics due to increased oxygen solubility and suppressed adsorption of phosphoric acid anions. Further enhancement of the catalytic activity can be obtained by operating the polymer electrolytes at higher temperatures. Efforts have been made to develop a polymer electrolyte...

  5. Fe3C-based oxygen reduction catalysts: synthesis, hollow spherical structures and applications in fuel cells

    DEFF Research Database (Denmark)

    Hu, Yang; Jensen, Jens Oluf; Zhang, Wei

    2015-01-01

    of the catalyst. At high pyrolytic temperatures of 700–800 °C, simultaneous formation of Fe3Cnanoparticles and encasing graphitic layers occur within the morphological confinement of the microspheres. With negligible surface nitrogen or iron functionality, the thus-obtained catalysts exhibit superior ORR activity...... and stability. A new ORR active phase of Fe3C nanoparticles encapsulated by thin graphitic layers is proposed. The activity and durability of the catalysts are demonstrated in both Nafion-based low temperature and acid doped polybenzimidazole-based high temperature proton exchange membrane fuel cells....

  6. New electrocatalyst support for high temperature PEM fuel cells (HT-PEMFC)

    Energy Technology Data Exchange (ETDEWEB)

    Boaventura, M.; Brandao, L.; Mendes, A. [Porto Univ. (PT). Lab. de Engenharia de Processos, Ambiente e Energia (LEPAE)

    2010-07-01

    This work compares the performance of electrocatalysts based on platinum supported in single-wall carbon nanohorns (Pt-SWNH) and supported in carbon black (Pt-carbon black) during high temperature PEM fuel operation. MEAs made of phosphoric acid doped polybenzimidazole (PBI/H{sub 3}PO{sub 4}) were characterized by polarization curves, electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), at 160 C. The Pt-SWNH electrocatalyst presented a higher electrochemical surface area (ESA) when compared to Pt-carbon black. However, electrochemical experiments showed a higher ohmic resistance of the Pt-SWNH electrode related to a higher hydrophobic character of the SWNH carbon. (orig.)

  7. Yb-doped polarizing fiber

    Science.gov (United States)

    Gillooly, A.; Webb, A. S.; Favero, F. C.; Bouchan, T.; Cooper, L. J.; Read, D.; Hill, M.

    2017-02-01

    An ytterbium (Yb) doped polarizing fiber is demonstrated. The fiber offers the opportunity to build all-fiber lasers with single polarization output and without the need for free-space polarizing components. Traditional single polarization fiber lasers utilize polarization-maintaining (PM) gain fiber with a single polarization stimulation signal. Whilst this results in an approximation to a single polarization laser, the spontaneous emission from the unstimulated polarization state limits the polarization extinction ratio (PER). The PER is further limited as the stimulated signal is prone to crosstalk. Furthermore, controlling amplitude modulation of the stimulated signal is critical for maximizing the peak power of an optical pulse, particularly for high energy lasers. If light is allowed to leak in to the unstimulated axis it will travel at a different velocity to the stimulated axis and can cross-couple back into the signal axis, creating an interference effect which leads to amplitude modulation on the signal pulse. Single-polarization Yb-doped fiber ensures that light on the fast axis is constantly attenuated; ensuring that light on the unstimulated axis cannot propagate and thus cannot degrade the PER or create amplitude modulation. In this paper we report on, to the best of our knowledge, the first demonstration of a single polarization Yb-doped bowtie optical fiber manufactured using a combination of Modified Chemical Vapor Deposition (MCVD) and rare-earth solution doping technology. The fiber has a single-polarization window of 80nm at the operating wavelength of 1060nm and a PER of >18dB. The fabrication and characterization of the fiber is reported.

  8. Doping, sundhed og fair konkurrencer

    DEFF Research Database (Denmark)

    Møller, Verner; Christiansen, Ask Vest

    Doping er blevet et nøgleord i reportagerne fra international sport. Atleternes præstationer kan først godkendes, når de har afgivet en negativ dopingprøve. Den omfattende kontrol retfærdiggøres som det, der skal sikre fair konkurrencer og en sund sport. Men har man egentlig begreb om det, man vil...

  9. FETs Based on Doped Polyaniline/Polyethylene Oxide Fibers

    Science.gov (United States)

    Theofylaktos, Noulie; Robinson, Daryl; Miranda, Felix; Pinto, Nicholas; Johnson, Alan, Jr.; MacDiarmid, Alan; Mueller, Carl

    2006-01-01

    A family of experimental highly miniaturized field-effect transistors (FETs) is based on exploitation of the electrical properties of nanofibers of polyaniline/ polyethylene oxide (PANi/PEO) doped with camphorsulfonic acid. These polymer-based FETs have the potential for becoming building blocks of relatively inexpensive, low-voltage, highspeed logic circuits that could supplant complementary metal oxide/semiconductor (CMOS) logic circuits. The development of these polymerbased FETs offers advantages over the competing development of FETs based on carbon nanotubes. Whereas it is difficult to control the molecular structures and, hence, the electrical properties of carbon nanotubes, it is easy to tailor the electrical properties of these polymerbased FETs, throughout the range from insulating through semiconducting to metallic, through choices of doping levels and chemical manipulation of polymer side chains. A further advantage of doped PANi/PEO nanofibers is that they can be made to draw very small currents and operate at low voltage levels, and thus are promising for applications in which there are requirements to use many FETs to obtain large computational capabilities while minimizing power demands. Fabrication of an experimental FET in this family begins with the preparation of a substrate as follows: A layer of silicon dioxide between 50 and 200 nm thick is deposited on a highly doped (resistivity 0.01 W.cm) silicon substrate, then gold electrodes/contact stripes are deposited on the oxide. Next, one or more fibers of camphorsulphonic acid-doped PANi/PEO having diameters of the order of 100 nm are electrospun onto the substrate so as to span the gap between the gold electrodes (see Figure 1). Figure 2 depicts measured current-versus-voltage characteristics of the device of Figure 1, showing that saturation channel currents occur at source-todrain potentials that are surprisingly low, relative to those of CMOS FETs. The hole mobility in the depletion regime in

  10. Synthesis and Photophysical Properties of ZnS Colloidal Particles Doped with Silver.

    Science.gov (United States)

    Hao; Sun; Yang; Zhang; Liu; Shen

    1998-08-15

    The synthesis and photophysical characterization of ZnS:Ag colloid are reported. The presence of mercaptoacetic acid has an important effect not only on the formation of doped and undoped ZnS but also on the photophysical properties. ZnS colloid doped with silver shows a strong green emission upon ultraviolet excitation, the intensity of which was enhanced significantly compared with that of the undoped colloid. The green emission was ascribed to a transition from a donor level such as anion vacancy to the levels of the Ag impurities. Copyright 1998 Academic Press.

  11. Highly luminescent S, N co-doped graphene quantum dots with broad visible absorption bands for visible light photocatalysts

    Science.gov (United States)

    Qu, Dan; Zheng, Min; Du, Peng; Zhou, Yue; Zhang, Ligong; Li, Di; Tan, Huaqiao; Zhao, Zhao; Xie, Zhigang; Sun, Zaicheng

    2013-11-01

    A facile hydrothermal synthesis route to N and S, N co-doped graphene quantum dots (GQDs) was developed by using citric acid as the C source and urea or thiourea as N and S sources. Both N and S, N doped GQDs showed high quantum yield (78% and 71%), excitation independent under excitation of 340-400 nm and single exponential decay under UV excitation. A broad absorption band in the visible region appeared in S, N co-doped GQDs due to doping with sulfur, which alters the surface state of GQDs. However, S, N co-doped GQDs show different color emission under excitation of 420-520 nm due to their absorption in the visible region. The excellent photocatalytic performance of the S, N co-doped GQD/TiO2 composites was demonstrated by degradation of rhodamine B under visible light. The apparent rate of S, N:GQD/TiO2 is 3 and 10 times higher than that of N:GQD/TiO2 and P25 TiO2 under visible light irradiation, respectively.A facile hydrothermal synthesis route to N and S, N co-doped graphene quantum dots (GQDs) was developed by using citric acid as the C source and urea or thiourea as N and S sources. Both N and S, N doped GQDs showed high quantum yield (78% and 71%), excitation independent under excitation of 340-400 nm and single exponential decay under UV excitation. A broad absorption band in the visible region appeared in S, N co-doped GQDs due to doping with sulfur, which alters the surface state of GQDs. However, S, N co-doped GQDs show different color emission under excitation of 420-520 nm due to their absorption in the visible region. The excellent photocatalytic performance of the S, N co-doped GQD/TiO2 composites was demonstrated by degradation of rhodamine B under visible light. The apparent rate of S, N:GQD/TiO2 is 3 and 10 times higher than that of N:GQD/TiO2 and P25 TiO2 under visible light irradiation, respectively. Electronic supplementary information (ESI) available: More XPS and UV-Vis spectra. See DOI: 10.1039/c3nr04402e

  12. Effect of doped and undoped POMA on the morphology and miscibility of blends with Poly(vinylidene fluoride (PVDF

    Directory of Open Access Journals (Sweden)

    I.S. Rocha

    1999-04-01

    Full Text Available The effect of the addition of small amounts of doped and undoped poly(o-methoxyaniline (POMA on the morphology of melt crystallized PVDF was investigated by means of polarized light optical microscopy. Undoped POMA (POMA-EB inhibits nucleation and growth of non ringed spherulites, partially formed by the polar gphase, whereas POMA doped with toluene sulfonic acid (POMA-TSA favors this process. Moreover, the doping of POMA increases the miscibility between the components of the PVDF/POMA blends, resulting in more homogeneous films. A possible cause of this miscibility increase and for the favoring of the polar gphase, is the higher polarity of the POMA chains as a result of the doping.

  13. Transmittance and Reflectance Spectra of Doped-Polyanisidine-Derived Film in the Visible Light Region

    Energy Technology Data Exchange (ETDEWEB)

    Tapia, A K G [Physics Divisio, Institute of Mathematical Sciences and Physics and University of the Philippines Los Banos, College, Laguna, Philippines, 4031 (Philippines); Catedral, M D [Physics Divisio, Institute of Mathematical Sciences and Physics and University of the Philippines Los Banos, College, Laguna, Philippines, 4031 (Philippines); Herrera, M U [Physics Divisio, Institute of Mathematical Sciences and Physics and University of the Philippines Los Banos, College, Laguna, Philippines, 4031 (Philippines); Tamayo, J P [Institute of Chemistry, University of the Philippines Los Banos, College, Laguna, Philippines, 4031 (Philippines); Rosario, E J R del [Institute of Chemistry, University of the Philippines Los Banos, College, Laguna, Philippines, 4031 (Philippines)

    2006-01-01

    Polyanisidine (PAnis) powder was synthesized using a standard procedure. It was doped with Hydrochloric (HCl) and Perchloric (HClO{sub 4}) Acids. The air-dried PAnis powder was then diluted using Dimethyl Formamide (DMF) as solvent and was spread out in a SiOx transparent glass substrate. An amorphous and semi-transparent film was fabricated seen in a polarizing microscope. The spectral analysis was carried out in the visible region from 400 nm to 700 nm. For HCl-doped sample, the high intensity region in the transmittance spectra occurred at the green portion while the high intensity region for the reflectance spectra was seen at the violet portion. Lastly, for the HClO4-doped sample, the peak intensities are at 536 nm and 516 nm for the transmittance and the reflectance spectra, respectively.

  14. Plasmonic Properties of Silicon Nanocrystals Doped with Boron and Phosphorus.

    Science.gov (United States)

    Kramer, Nicolaas J; Schramke, Katelyn S; Kortshagen, Uwe R

    2015-08-12

    Degenerately doped silicon nanocrystals are appealing plasmonic materials due to silicon's low cost and low toxicity. While surface plasmonic resonances of boron-doped and phosphorus-doped silicon nanocrystals were recently observed, there currently is poor understanding of the effect of surface conditions on their plasmonic behavior. Here, we demonstrate that phosphorus-doped silicon nanocrystals exhibit a plasmon resonance immediately after their synthesis but may lose their plasmonic response with oxidation. In contrast, boron-doped nanocrystals initially do not exhibit plasmonic response but become plasmonically active through postsynthesis oxidation or annealing. We interpret these results in terms of substitutional doping being the dominant doping mechanism for phosphorus-doped silicon nanocrystals, with oxidation-induced defects trapping free electrons. The behavior of boron-doped silicon nanocrystals is more consistent with a strong contribution of surface doping. Importantly, boron-doped silicon nanocrystals exhibit air-stable plasmonic behavior over periods of more than a year.

  15. Moral entrepreneurship and doping cultures in sport

    NARCIS (Netherlands)

    Stokvis, R.

    2003-01-01

    In this article, the fight against doping has been analyzed as an ongoing process of social definition. It is dependent on the development of power relations within and outside the world of sport. To analyze these dependencies, I identified a variety of important doping cultures in sport and studied

  16. Thermoluminescence dosimetry of rare earth doped calcium ...

    Indian Academy of Sciences (India)

    Unknown

    CaAl2O4) doped with different rare earth ions have been studied and their suitability for radiation dosimetry applications is discussed. It is observed that monocalcium aluminate doped with cerium is a good dosimeter having linear response up to ...

  17. Phosphorous Doping of Nanostructured Crystalline Silicon

    DEFF Research Database (Denmark)

    Plakhotnyuk, Maksym; Davidsen, Rasmus Schmidt; Steckel, André

    with phosphorous (POCl3) in the temperature range 850-1000oC for 15 and 20 min, respectively. Sheet resistance measurements show slight differences in doping density between planar, KOH pyramidal and bSi structures. bSi samples have lower sheet resistance, pointing to higher doping density presumably due...

  18. Electronic properties of magnetically doped nanotubes

    Indian Academy of Sciences (India)

    Unknown

    body of publications since their discovery in 1991 (Iijima. 1991). Recent experimental (Lee et al 1997; Rao et al. 1997; Grigorian et al 1998a, b) and theoretical (Miya- moto et al 1995; Esfarjani et al 1999) studies on doping nanotubes focused on doping by alkali metal or halogene elements as electron donors or acceptors, ...

  19. Ultratough single crystal boron-doped diamond

    Science.gov (United States)

    Hemley, Russell J [Carnegie Inst. for Science, Washington, DC ; Mao, Ho-Kwang [Carnegie Inst. for Science, Washington, DC ; Yan, Chih-Shiue [Carnegie Inst. for Science, Washington, DC ; Liang, Qi [Carnegie Inst. for Science, Washington, DC

    2015-05-05

    The invention relates to a single crystal boron doped CVD diamond that has a toughness of at least about 22 MPa m.sup.1/2. The invention further relates to a method of manufacturing single crystal boron doped CVD diamond. The growth rate of the diamond can be from about 20-100 .mu.m/h.

  20. Heteroatom doped graphene in photocatalysis: A review

    Energy Technology Data Exchange (ETDEWEB)

    Putri, Lutfi Kurnianditia; Ong, Wee-Jun [Chemical Engineering Discipline, School of Engineering, Monash University, Jalan Lagoon Selatan, Bandar Sunway, 47500 Selangor (Malaysia); Chang, Wei Sea [Mechanical Engineering Discipline, School of Engineering, Monash University, Jalan Lagoon Selatan, Bandar Sunway, 47500 Selangor (Malaysia); Chai, Siang-Piao, E-mail: chai.siang.piao@monash.edu [Chemical Engineering Discipline, School of Engineering, Monash University, Jalan Lagoon Selatan, Bandar Sunway, 47500 Selangor (Malaysia)

    2015-12-15

    Graphical abstract: - Highlights: • Doping graphene with foreign atoms extends its function in the photocatalyst system. • Chemically doped graphene improved the electrical conductivity. • Chemically doped graphene outperform conventional rGO as a semiconductor support. • Chemically doped graphene cause bandgap opening and formation of catalytic sites. • Chemically doped graphene can behave as functional standalone photocatalyst. - Abstract: Photocatalysis has been a focus of great attention due to its useful environmental applications such as eliminating hazardous pollutants and generating sustainable energy. Coincidentally, graphene, a 2D allotrope of carbon, has also infiltrated many research fields due to its outstanding properties – photocatalysis being no exception. As of recent, there has been growing research focus on heteroatom (O, N, B, P and S) doping of graphene and its emergent application opportunities. In this study, rather than the familiar graphene as the electron transfer medium that is normally integrated in a photocatalyst system, we contrarily explore the implication of heteroatom doped graphene and the underlying mechanism behind their advantageous uses in photocatalysis. This review surveys the literature and highlights recent progress and challenges in the development of chemically doped graphene in the photocatalysis scene. It is desired that this review will promote awareness and encourage further investigations for the development in this budding research area.

  1. Thermoluminescence dosimetry of rare earth doped calcium ...

    Indian Academy of Sciences (India)

    The thermoluminescence (TL) properties of calcium aluminate (CaAl2O4) doped with different rare earth ions have been studied and their suitability for radiation dosimetry applications is discussed. It is observed that monocalcium aluminate doped with cerium is a good dosimeter having linear response up to about 4 kGy of ...

  2. Synthesis, Characterization and Evaluation of the Cytotoxicity of Ni-Doped Zn(Se,S Quantum Dots

    Directory of Open Access Journals (Sweden)

    Melissa Cruz-Acuña

    2015-01-01

    Full Text Available Quantum dots (QDs are semiconductor nanocrystals with desirable optical properties for biological applications, such as bioimaging and drug delivery. However, the potential toxicity of these nanostructures in biological systems limits their application. The present work is focused on the synthesis, characterization, and evaluation of the toxicity of water-stable Ni-doped Zn(Se,S QDs. Also, the study of nondoped nanostructures was included for comparison purposes. Ni-doped nanostructures were produced from zinc chloride and selenide aqueous solutions in presence of 3-mercaptopropionic acid and Ni molar concentration of 0.001 M. In order to evaluate the potential cytoxicity of these doped nanostructures, human pancreatic carcinoma cells (PANC-1 were used as model. The cell viability was monitored in presence of Ni-doped Zn(Se,S QDs at concentrations ranging from 0 μg/mL to 500 μg/mL and light excited Ni-doped Zn(Se,S nanostructures were evaluated at 50 μg/mL. Results suggested that Ni-doped Zn(Se,S nanostructures were completely safe to PANC-1 when concentrations from 0 μg/mL to 500 μg/mL were used, whereas non-doped nanostructures evidenced toxicity at concentrations higher than 200 μg/mL. Also, Ni-doped Zn(Se,S QDs under light excitation do not evidence toxicity to PANC-1. These findings suggest strongly that Zn(Se,S nanostructures doped with nickel could be used in a safe manner in light-driving biological applications and drug delivery.

  3. Probing Photocatalytic Characteristics of Sb-Doped TiO2 under Visible Light Irradiation

    Directory of Open Access Journals (Sweden)

    Lingjing Luo

    2014-01-01

    Full Text Available Sb-doped TiO2 nanoparticle with varied dopant concentrations was synthesized using titanium tetrachloride (TiCl4 and antimony chloride (SbCl3 as the precursors. The properties of Sb-doped TiO2 nanoparticles were characterized by X-ray diffraction (XRD, scanning electron microscope (SEM, fluorescence spectrophotometer, and Uv-vis spectrophotometer. The absorption edge of TiO2 nanoparticles could be extended to visible region after doping with antimony, in contrast to the UV absorption of pure TiO2. The results showed that the photocatalytic activity of Sb-doped TiO2 nanoparticles was much more active than pure TiO2. The 0.1% Sb-doped TiO2 nanoparticles demonstrated the best photocatalytic activity which was better than that of the Degussa P25 under visible light irradiation using terephthalic acid as fluorescent probe. The effects of Sb dopant on the photocatalytic activity and the involved mechanism were extensively investigated in this work as well.

  4. [Cardiovascular alterations associated with doping].

    Science.gov (United States)

    Thieme, D; Büttner, A

    2015-05-01

    Doping -the abuse of anabolic-androgenic steroids in particular- is widespread in amateur and recreational sports and does not solely represent a problem of professional sports. Excessive overdose of anabolic steroids is well documented in bodybuilding or powerlifting leading to significant side effects. Cardiovascular damages are most relevant next to adverse endocrine effects.Clinical cases as well as forensic investigations of fatalities or steroid consumption in connection with trafficking of doping agents provide only anecdotal evidence of correlations between side effects and substance abuse. Analytical verification and self-declarations of steroid users have repeatedly confirmed the presumption of weekly dosages between 300 and 2000 mg, extra to the fact that co-administration of therapeutics to treat side-effects represent a routine procedure. Beside the most frequent use of medications used to treat erectile dysfunction or estrogenic side-effects, a substantial number of antihypertensive drugs of various classes, i.e. beta-blockers, diuretics, angiotensin II receptor antagonists, calcium channel blockers, as well as ACE inhibitors were recently confiscated in relevant doping cases. The presumptive correlation between misuse of anabolic steroids and self-treatment of cardiovascular side effects was explicitly confirmed by detailed user statements.Two representative fatalities of bodybuilders were introduced to outline characteristic, often lethal side effects of excessive steroid abuse. Moreover, illustrative autopsy findings of steroid acne, thrombotic occlusion of Ramus interventricularis anterior and signs of cardiac infarctions are presented.A potential steroid abuse should be carefully considered in cases of medical consultations of patients exhibiting apparent constitutional modifications and corresponding adverse effects. Moreover, common self-medications -as frequently applied by steroid consumers- should be taken into therapeutic considerations.

  5. Electrochemical mineralization pathway of quinoline by boron-doped diamond anodes.

    Science.gov (United States)

    Wang, Chunrong; Ma, Keke; Wu, Tingting; Ye, Min; Tan, Peng; Yan, Kecheng

    2016-04-01

    Boron-doped diamond anodes were selected for quinoline mineralization, and the resulting intermediates, phenylpropyl aldehyde, phenylpropionic acid, and nonanal were identified and followed during quinoline oxidation by gas chromatography-mass spectrometry and high-performance liquid chromatography. The evolutions of formic acid, acetic acid, oxalic acid, NO2(-), NO3(-), and NH4(+) were quantified. A new reaction pathway for quinoline mineralization by boron-doped diamond anodes has been proposed, where the pyridine ring in quinoline is cleaved by a hydroxyl radical giving phenylpropyl aldehyde and NH4(+). Phenylpropyl aldehyde is quickly oxidized into phenylpropionic acid, and the benzene ring is cleaved giving nonanal. This is further oxidized to formic acid, acetic acid, and oxalic acid. Finally, these organic intermediates are mineralized to CO2 and H2O. NH4(+) is also oxidized to NO2(-) and on to NO3(-). The results will help to gain basic reference for clearing intermediates and their toxicity. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. Phosphate-Doped Carbon Black as Pt Catalyst Support: Co-catalytic Functionality for Dimethyl Ether and Methanol Electro-oxidation

    DEFF Research Database (Denmark)

    Yin, Min; Huang, Yunjie; Li, Qingfeng

    2014-01-01

    Niobium-phosphate-doped (NbP-doped) carbon blacks were prepared as the composite catalyst support for Pt nanoparticles. Functionalities of the composite include intrinsic proton conductivity, surface acidity, and interfacial synergistic interactions with methanol and dimethyl ether (DME). The sup......Niobium-phosphate-doped (NbP-doped) carbon blacks were prepared as the composite catalyst support for Pt nanoparticles. Functionalities of the composite include intrinsic proton conductivity, surface acidity, and interfacial synergistic interactions with methanol and dimethyl ether (DME......). The supported Pt catalysts show significant improvement in catalytic activity towards the direct oxidation of methanol and DME, attributable to the enhanced adsorption and dehydrogenation of methanol and DME, as well as the presence of activated OH species in the catalysts. The latter is demonstrated...

  7. GaAs MESFET with lateral non-uniform doping

    Science.gov (United States)

    Wang, Y. C.; Bahrami, M.

    1983-01-01

    An analytical model of the GaAs MESFET with arbitrary non-uniform doping is presented. Numerical results for linear lateral doping profile are given as a special case. Theoretical considerations predict that better device linearity and improved F(T) can be obtained by using linear lateral doping when doping density increases from source to drain.

  8. The importance of cooling of urine samples for doping analysis

    NARCIS (Netherlands)

    Kuenen, J.G.; Konings, W.N.

    2009-01-01

    Storing and transporting of urine samples for doping analysis, as performed by the anti-doping organizations associated with the World Anti-Doping Agency, does not include a specific protocol for cooled transport from the place of urine sampling to the doping laboratory, although low cost cooling

  9. The importance of cooling of urine samples for doping analysis

    NARCIS (Netherlands)

    Kuenen, J. Gijs; Konings, Wil N.

    Storing and transporting of urine samples for doping analysis, as performed by the anti-doping organizations associated with the World Anti-Doping Agency, does not include a specific protocol for cooled transport from the place of urine sampling to the doping laboratory, although low cost cooling

  10. Nonlinear optical properties of natural laccaic acid dye studied using Z-scan technique

    CSIR Research Space (South Africa)

    Zongo, S

    2015-08-01

    Full Text Available We have investigated the nonlinear optical properties, including the optical limiting behaviour for five different concentrations of laccaic acid dye in solution and a thin film obtained through doping in poly (methyl methacrylate) (PMMA) polymer...

  11. Dual doped graphene oxide for electrochemical sensing of europium ion

    Science.gov (United States)

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

    2017-05-01

    This present work represents a single step hydrothermal method for the preparation of N, and N, S dual doped graphene oxide (GO). First time, a comparative electrochemical study between single dope and dual doped GO was carried out using potassium ferrocyanide as an electro-active probe molecule and found that the dual doped GO has the highest electrocatalytic activity than single doped, due to the presence of two heteroatoms as a doping material. Afterwards, the dual doped GO was successfully applied for the electrochemical detection of a rare earth element i.e. europium, with LOD value of 5.92 μg L-1.

  12. Radical-assisted chemical doping for chemically derived graphene

    Science.gov (United States)

    Ishikawa, Ryousuke; Ko, Pil Ju; Bando, Masashi; Kurokawa, Yasuyoshi; Sandhu, Adarsh; Konagai, Makoto

    2013-12-01

    Carrier doping of graphene is one of the most challenging issues that needs to be solved to enable its use in various applications. We developed a carrier doping method using radical-assisted conjugated organic molecules in the liquid phase and demonstrated all-wet fabrication process of doped graphene films without any vacuum process. Charge transfer interaction between graphene and dopant molecules was directly investigated by spectroscopic studies. The resistivity of the doped graphene films was drastically decreased by two orders of magnitude. The resistivity was improved by not only carrier doping but the improvement in adhesion of doped graphene flakes. First-principles calculation supported the model of our doping mechanism.

  13. Hydrothermal fabrication of selectively doped organic assisted advanced ZnO nanomaterial for solar driven photocatalysis.

    Science.gov (United States)

    Namratha, K; Byrappa, K; Byrappa, S; Venkateswarlu, P; Rajasekhar, D; Deepthi, B K

    2015-08-01

    Hydrothermal fabrication of selectively doped (Ag(+)+Pd(3+)) advanced ZnO nanomaterial has been carried out under mild pressure temperature conditions (autogeneous; 150°C). Gluconic acid has been used as a surface modifier to effectively control the particle size and morphology of these ZnO nanoparticles. The experimental parameters were tuned to achieve optimum conditions for the synthesis of selectively doped ZnO nanomaterials with an experimental duration of 4 hr. These selectively doped ZnO nanoparticles were characterized using powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-Vis spectroscopy and scanning electron microscopy (SEM). The solar driven photocatalytic studies have been carried out for organic dyes, i.e., Procion MX-5B dye, Cibacron Brilliant Yellow dye, Indigo Carmine dye, separately and all three mixed, by using gluconic acid modified selectively doped advanced ZnO nanomaterial. The influence of catalyst, its concentration and initial dye concentration resulted in the photocatalytic efficiency of 89% under daylight. Copyright © 2015. Published by Elsevier B.V.

  14. One-step synthesis of nitrogen-doped ZnO nanocrystallites and their properties

    Science.gov (United States)

    Zheng, Min; Wu, Jiaqing

    2009-03-01

    Nitrogen-doped ZnO nanocrystallites with primary diameter in the range of 30-50 nm were synthesized rapidly by self-assembly combustion technique using urea and citric acid as fuels, zinc nitrate as oxidant. The variation of adiabatic flame temperature with the various fuel compounds was calculated theoretically according to the thermodynamic concept. XRD, SEM and XPS were used to characterize the as-synthesized products. The anti-ultraviolet and anti-bacterium ability of the products were estimated by testing the UPF index and repressing-bacterium circle diameter of the cotton fabrics, which were treated using the as-synthesized products. The results show that a small quantity of citric acid has excellent coordinated action with urea and accelerates the nitrogen doping reaction course, obtaining perfect nitrogen-doped ZnO nanocrystallites with uniform color and particles size. The analysis of XPS spectrum shows that the nitrogen incorporation produces an N-O bonding region. The incorporation of nitrogen greatly improves the anti-ultraviolet and anti-bacterium properties of ZnO nanocrystallites, which can be attributed to the change of surface properties of nitrogen-doped ZnO, such as O vacancies and crystal deficiency.

  15. Doping Ag in ZnO Nanorods to Improve the Performance of Related Enzymatic Glucose Sensors

    Directory of Open Access Journals (Sweden)

    Fan Zhou

    2017-09-01

    Full Text Available In this paper, the performance of a zinc oxide (ZnO nanorod-based enzymatic glucose sensor was enhanced with silver (Ag-doped ZnO (ZnO-Ag nanorods. The effect of the doped Ag on the surface morphologies, wettability, and electron transfer capability of the ZnO-Ag nanorods, as well as the catalytic character of glucose oxidase (GOx and the performance of the glucose sensor was investigated. The results indicate that the doped Ag slightly weakens the surface roughness and hydrophilicity of the ZnO-Ag nanorods, but remarkably increases their electron transfer ability and enhances the catalytic character of GOx. Consequently, the combined effects of the above influencing factors lead to a notable improvement of the performance of the glucose sensor, that is, the sensitivity increases and the detection limit decreases. The optimal amount of the doped Ag is determined to be 2 mM, and the corresponding glucose sensor exhibits a sensitivity of 3.85 μA/(mM·cm2, detection limit of 1.5 μM, linear range of 1.5 × 10−3–6.5 mM, and Michaelis-Menten constant of 3.87 mM. Moreover, the glucose sensor shows excellent selectivity to urea, ascorbic acid, and uric acid, in addition to displaying good storage stability. These results demonstrate that ZnO-Ag nanorods are promising matrix materials for the construction of other enzymatic biosensors.

  16. Studies on biphenyl disulphonic acid doped polyanilines: Synthesis ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 35; Issue 3. Studies on biphenyl ... M Vijayan1. Functional Materials Division, Central Electrochemical Research Institute, Karaikudi 630 006, India; Polymers and Functional Materials Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India ...

  17. Synthesis and optical characterization of acid-doped polyaniline thin ...

    African Journals Online (AJOL)

    Polyaniline has attracted much interest among researchers because of its reasonably good conductivity, stability, ease of preparation, affordability and redox properties compared to other organic compounds. In this work, Polyaniline (PANI) thin films were synthesized by chemical oxidative polymerization of aniline in the ...

  18. synthesis and optical characterization of acid-doped polyaniline thin ...

    African Journals Online (AJOL)

    HOD

    Polyaniline has attracted much interest among researchers because of its reasonably good conductivity, stability, ease of preparation, affordability and redox properties compared to other organic compounds. In this work, Polyaniline. (PANI) thin films were synthesized by chemical oxidative polymerization of aniline in the ...

  19. synthesis and optical characterization of acid-doped polyaniline thin ...

    African Journals Online (AJOL)

    HOD

    (PANI) thin films were synthesized by chemical oxidative polymerization of aniline in the presence of Hydrochloric .... Applied Physics, Vol. 11, Number 2, pp 217-222,. 2010. [2] Vhanakhande, B., Madhale, K.and Puri, V. “Microwave properties of electropolymerised polyaniline thin films on stainless steel”, Scholars.

  20. IR-doped ruthenium oxide catalyst for oxygen evolution

    Science.gov (United States)

    Valdez, Thomas I. (Inventor); Narayanan, Sekharipuram R. (Inventor)

    2012-01-01

    A method for preparing a metal-doped ruthenium oxide material by heating a mixture of a doping metal and a source of ruthenium under an inert atmosphere. In some embodiments, the doping metal is in the form of iridium black or lead powder, and the source of ruthenium is a powdered ruthenium oxide. An iridium-doped or lead-doped ruthenium oxide material can perform as an oxygen evolution catalyst and can be fabricated into electrodes for electrolysis cells.

  1. Empathic and Self-Regulatory Processes Governing Doping Behavior

    Directory of Open Access Journals (Sweden)

    Ian D. Boardley

    2017-09-01

    Full Text Available Evidence associating doping behavior with moral disengagement (MD has accumulated over recent years. However, to date, research examining links between MD and doping has not considered key theoretically grounded influences and outcomes of MD. As such, there is a need for quantitative research in relevant populations that purposefully examines the explanatory pathways through which MD is thought to operate. Toward this end, the current study examined a conceptually grounded model of doping behavior that incorporated empathy, doping self-regulatory efficacy (SRE, doping MD, anticipated guilt and self-reported doping/doping susceptibility. Participants were specifically recruited to represent four key physical-activity contexts and consisted of team- (n = 195 and individual- (n = 169 sport athletes and hardcore- (n = 125 and corporate- (n = 121 gym exercisers representing both genders (nmale = 371; nfemale = 239; self-reported lifetime prevalence of doping across the sample was 13.6%. Each participant completed questionnaires assessing the aforementioned variables. Structural equation modeling indicated strong support for all study hypotheses. Specifically, we established: (a empathy and doping SRE negatively predicted reported doping; (b the predictive effects of empathy and doping SRE on reported doping were mediated by doping MD and anticipated guilt; (c doping MD positively predicted reported doping; (d the predictive effects of doping MD on reported doping were partially mediated by anticipated guilt. Substituting self-reported doping for doping susceptibility, multisample analyses then demonstrated these predictive effects were largely invariant between males and females and across the four physical-activity contexts represented. These findings extend current knowledge on a number of levels, and in doing so aid our understanding of key psychosocial processes that may govern doping behavior across key physical-activity contexts.

  2. FIFA's approach to doping in football

    Science.gov (United States)

    Dvorak, J; Graf‐Baumann, T; D'Hooghe, M; Kirkendall, D; Taennler, H; Saugy, M

    2006-01-01

    Background and objectives FIFA's anti‐doping strategy relies on education and prevention. A worldwide network of physicians guarantees doping control procedures that are straightforward and leave no place for cheating. FIFA actively acknowledges its responsibility to protect players from harm and ensure equal chances for all competitors by stringent doping control regulations, data collection of positive samples, support of research, and collaboration with other organisations. This article aims to outline FIFA's approach to doping in football. Method Description of FIFA's doping control regulations and procedures, statistical analysis of FIFA database on doping control, and comparison with data obtained by WADA accredited laboratories as for 2004. Results Data on positive doping samples per substance and confederation/nation documented at the FIFA medical office from 1994 to 2005 are provided. According to the FIFA database, the incidence of positive cases over the past 11 years was 0.12%, with about 0.42% in 2004 (based on the assumption of 20 750 samples per year) and 0.37% in 2005. Especially important in this regard is the extremely low incidence of the true performance enhancing drugs such as anabolic steroids and stimulants. However, there is a need for more consistent data collection and cross checks among international anti‐doping agencies as well as for further studies on specific substances, methods, and procedures. With regard to general health impairments in players, FIFA suggests that principles of occupational medicine should be considered and treatment with banned substances for purely medical reasons should be permitted to enable players to carry out their profession. At the same time, a firm stand has to be taken against suppression of symptoms by medication with the aim of meeting the ever increasing demands on football players. Conclusion Incidence of doping in football seems to be low, but much closer collaboration and further

  3. Ce-doped titania nanoparticles: The effects of doped amount and calcination temperature on photocatalytic activity

    Science.gov (United States)

    Shi, Jianwen; Zou, Yajun; Ma, Dandan

    2017-01-01

    A series of Ce-doped TiO2 nanoparticles with different doped amount and calcination temperature were prepared by sol-gel method. These obtained samples were characterized with X-ray diffraction (XRD), transmission electron microscope (TEM) and ultraviolet-visible diffuse reflectance spectra (DRS), and their photocatalytic activities were evaluated by the photocatalytic degradation of methyl orange. Results showed that Ce doping inhibits the growth of crystal size and the phase transformation from anatase to rutile, leads to lattice distortion and expansion of TiO2. Furthermore, Ce doping brings the red-shift of absorption profile and the increase of photons absorption in the range of 400-600 nm. Photocatalytic degradation of methyl orange shows that Ce doping improves the photocatalytic activity of TiO2. The optimal doped amount is 0.05 mol% and the optimal calcined temperature is 600 °C for the maximum photocatalytic degradation efficiency in our experiment.

  4. Phase transformations upon doping in WO3

    Science.gov (United States)

    Wang, Wennie; Janotti, Anderson; Van de Walle, Chris G.

    2017-06-01

    High levels of doping in WO3 have been experimentally observed to lead to structural transformation towards higher symmetry phases. We explore the structural phase diagram with charge doping through first-principles methods based on hybrid density functional theory, as a function of doping the room-temperature monoclinic phase transitions to the orthorhombic, tetragonal, and finally cubic phase. Based on a decomposition of energies into electronic and strain contributions, we attribute the transformation to a gain in energy resulting from a lowering of the conduction band on an absolute energy scale.

  5. Alternative medicine and doping in sports

    Directory of Open Access Journals (Sweden)

    Benjamin Koh

    2012-01-01

    Full Text Available Athletes are high achievers who may seek creative or unconventional methods to improve performance. The literature indicates that athletes are among the heaviest users of complementary and alternative medicine (CAM and thus may pioneer population trends in CAM use. Unlike non-athletes, athletes may use CAM not just for prevention, treatment or rehabilitation from illness or injuries, but also for performance enhancement. Assuming that athletes’ creative use of anything unconventional is aimed at “legally” improving performance, CAM may be used because it is perceived as more “natural” and erroneously assumed as not potentially doping. This failure to recognise CAMs as pharmacological agents puts athletes at risk of inadvertent doping.The general position of the World Anti-Doping Authority (WADA is one of strict liability, an application of the legal proposition that ignorance is no excuse and the ultimate responsibility is on the athlete to ensure at all times whatever is swallowed, injected or applied to the athlete is both safe and legal for use. This means that a violation occurs whether or not the athlete intentionally or unintentionally, knowingly or unknowingly, used a prohibited substance/method or was negligent or otherwise at fault. Athletes are therefore expected to understand not only what is prohibited, but also what might potentially cause an inadvertent doping violation. Yet, as will be discussed, athlete knowledge on doping is deficient and WADA itself sometimes changes its position on prohibited methods or substances. The situation is further confounded by the conflicting stance of anti-doping experts in the media. These highly publicised disagreements may further portray inconsistencies in anti-doping guidelines and suggest to athletes that what is considered doping is dependent on the dominant political zeitgeist. Taken together, athletes may believe that unless a specific and explicit ruling is made, guidelines are

  6. Gas Immersion Laser Doping for superconducting nanodevices

    Energy Technology Data Exchange (ETDEWEB)

    Chiodi, F. [Institut d’Electronique Fondamentale, CNRS-Université Paris-Sud, F-91405 Orsay (France); Grockowiak, A. [Institut Néel, CNRS, BP 166, F-38042 Grenoble (France); CEA, INAC, UMR-E9001/UJF, LATEQS, 17 Rue des Martyrs, F-38054 Grenoble (France); Duvauchelle, J.E. [CEA, INAC, UMR-E9001/UJF, LATEQS, 17 Rue des Martyrs, F-38054 Grenoble (France); Fossard, F. [Institut d’Electronique Fondamentale, CNRS-Université Paris-Sud, F-91405 Orsay (France); Lefloch, F. [CEA, INAC, UMR-E9001/UJF, LATEQS, 17 Rue des Martyrs, F-38054 Grenoble (France); Klein, T. [Institut Néel, CNRS, BP 166, F-38042 Grenoble (France); Marcenat, C. [CEA, INAC, UMR-E9001/UJF, LATEQS, 17 Rue des Martyrs, F-38054 Grenoble (France); Institut Néel, CNRS, BP 166, F-38042 Grenoble (France); Débarre, D. [Institut d’Electronique Fondamentale, CNRS-Université Paris-Sud, F-91405 Orsay (France)

    2014-05-01

    We have conceived and fabricated Superconductor/Normal metal/Superconductor Josephson junctions made entirely of boron doped Silicon. We have used Gas Immersion Laser Doping to fabricate SN bilayers with good ohmic interfaces and well controlled concentration and doping depth. Standard fabrication processes, optimised for silicon, were employed to nanostructure the bilayers without affecting their transport properties. The junctions thus fabricated are proximity superconducting and show well understood I–V characteristics. This research opens the road to all-silicon, non-dissipative, Josephson Field Effect Transistors.

  7. Alternative medicine and doping in sports.

    Science.gov (United States)

    Koh, Benjamin; Freeman, Lynne; Zaslawski, Christopher

    2012-01-01

    Athletes are high achievers who may seek creative or unconventional methods to improve performance. The literature indicates that athletes are among the heaviest users of complementary and alternative medicine (CAM) and thus may pioneer population trends in CAM use. Unlike non-athletes, athletes may use CAM not just for prevention, treatment or rehabilitation from illness or injuries, but also for performance enhancement. Assuming that athletes' creative use of anything unconventional is aimed at "legally" improving performance, CAM may be used because it is perceived as more "natural" and erroneously assumed as not potentially doping. This failure to recognise CAMs as pharmacological agents puts athletes at risk of inadvertent doping.The general position of the World Anti-Doping Authority (WADA) is one of strict liability, an application of the legal proposition that ignorance is no excuse and the ultimate responsibility is on the athlete to ensure at all times whatever is swallowed, injected or applied to the athlete is both safe and legal for use. This means that a violation occurs whether or not the athlete intentionally or unintentionally, knowingly or unknowingly, used a prohibited substance/method or was negligent or otherwise at fault. Athletes are therefore expected to understand not only what is prohibited, but also what might potentially cause an inadvertent doping violation. Yet, as will be discussed, athlete knowledge on doping is deficient and WADA itself sometimes changes its position on prohibited methods or substances. The situation is further confounded by the conflicting stance of anti-doping experts in the media. These highly publicised disagreements may further portray inconsistencies in anti-doping guidelines and suggest to athletes that what is considered doping is dependent on the dominant political zeitgeist. Taken together, athletes may believe that unless a specific and explicit ruling is made, guidelines are open to interpretation

  8. Photocatalytic degradation of humic substances in aqueous solution using Cu-doped ZnO nanoparticles under natural sunlight irradiation.

    Science.gov (United States)

    Maleki, Afshin; Safari, Mahdi; Shahmoradi, Behzad; Zandsalimi, Yahya; Daraei, Hiua; Gharibi, Fardin

    2015-11-01

    In this study, Cu-doped ZnO nanoparticles were investigated as an efficient synthesized catalyst for photodegradation of humic substances in aqueous solution under natural sunlight irradiation. Cu-doped ZnO nanocatalyst was prepared through mild hydrothermal method and was characterized using FT-IR, powder XRD and SEM techniques. The effect of operating parameters such as doping ratio, initial pH, catalyst dosage, initial concentrations of humic substances and sunlight illuminance were studied on humic substances degradation efficiency. The results of characterization analyses of samples confirmed the proper synthesis of Cu-doped ZnO nanocatalyst. The experimental results indicated the highest degradation efficiency of HS (99.2%) observed using 1.5% Cu-doped ZnO nanoparticles at reaction time of 120 min. Photocatalytic degradation efficiency of HS in a neutral and acidic pH was much higher than that at alkaline pH. Photocatalytic degradation of HS was enhanced with increasing the catalyst dosage and sunlight illuminance, while increasing the initial HS concentration led to decrease in the degradation efficiency of HS. Conclusively, Cu-doped ZnO nanoparticles can be used as a promising and efficient catalyst for degradation of HS under natural sunlight irradiation.

  9. Inverted polymer solar cells with sol-gel derived cesium-doped zinc oxide thin film as a buffer layer

    Science.gov (United States)

    Ahmadi, Mehdi; Mirabbaszadeh, Kavoos; Salari, Saeid; Fatehy, Hamed

    2014-09-01

    An inverted structure of polymer solar cells based on Poly(3-hexylthiophene)(P3HT):[6-6] Phenyl-(6) butyric acid methyl ester (PCBM) with thin films of sol-gel derived Cesium doped ZnO (Cs:ZnO) was developed as an efficient cathode buffer layer. Doped and undoped thin films were deposited using a less studied method, doctor blade, which was compatible with Roll-2-Roll printing method. By comparing the effect of Cs:ZnO thin films with various dopant ratio on the performance of inverted polymer solar cells, 0.5% Cs doped ZnO was found as the most effective doping level among the selected doping ratios. Using 30 nm thickness of 0.5% Csn:ZnO thin film as an electron transport layer led to the average efficiency which was significantly higher than (9%) that of similar devices employing the same thickness of undoped ZnO film. Results showed that the devices fabricated with 1% and 2% cesium doped ZnO yielded lower power conversion efficiency, which could be due to the lower FF. Also, the influence of dopant incorporation on the optical transmittance and electrical conductivity of ZnO films was investigated.

  10. A simple preparation of nitrogen doped titanium dioxide nanocrystals with exposed (001) facets with high visible light activity.

    Science.gov (United States)

    Zhou, Xiaosong; Peng, Feng; Wang, Hongjuan; Yu, Hao; Fang, Yueping

    2012-01-14

    Nanoscaled nitrogen doped anatase TiO(2) with dominant (001) facets, which exhibited high photocatalytic activity and excellent photoelectrochemical properties under visible light irradiation, was successfully synthesized by solvothermal treatment of TiN in acidic NaBF(4) solution for the first time. This journal is © The Royal Society of Chemistry 2012

  11. Highly concentrated, stable nitrogen-doped graphene for supercapacitors: Simultaneous doping and reduction

    Energy Technology Data Exchange (ETDEWEB)

    Jiang Baojiang [College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin (China); Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People' s Republic of China, Heilongjiang University, Harbin (China); Tian Chungui; Wang Lei; Sun Li; Chen Chen; Nong Xiaozhen [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People' s Republic of China, Heilongjiang University, Harbin (China); Qiao Yingjie, E-mail: qiaoyingjie@hrbeu.edu.cn [College of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin (China); Fu Honggang, E-mail: fuhg@vip.sina.com [Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education of the People' s Republic of China, Heilongjiang University, Harbin (China)

    2012-02-01

    In this work, we developed a concentrated ammonia-assisted hydrothermal method to obtain N-doped graphene sheets by simultaneous N-doping and reduction of graphene oxide (GO) sheets. The effects of hydrothermal temperature on the surface chemistry and the structure of N-doped graphene sheets were also investigated. X-ray photoelectron spectroscopy (XPS) study of N-doped graphene reveals that the highest doping level of 7.2% N is achieved at 180 Degree-Sign C for 12 h. N binding configurations of sample consist of pyridine N, quaternary N, and pyridine-N oxides. N doping is accompanied by the reduction of GO with decreases in oxygen levels from 34.8% in GO down to 8.5% in that of N-doped graphene. Meanwhile, the sample exhibits excellent N-doped thermal stability. Electrical measurements demonstrate that products have higher capacitive performance than that of pure graphene, the maximum specific capacitance of 144.6 F/g can be obtained which ascribe the pseudocapacitive effect from the N-doping. The samples also show excellent long-term cycle stability of capacitive performance.

  12. Erbium Doped Fiber Optic Gravimeter

    Science.gov (United States)

    Pérez-Sánchez, G. G.; Pérez-Torres, J. R.; Flores-Bravo, J. A.; Álvarez-Chávez, J. A.; Martínez-Piñón, F.

    2017-01-01

    Gravimeters are devices that can be used in a wide range of applications, such as mining, seismology, geodesy, archeology, geophysics and many others. These devices have great sensibility, which makes them susceptible to external vibrations like electromagnetic waves. There are several technologies regarding gravimeters that are of use in industrial metrology. Optical fiber is immune to electromagnetic interference, and together with long period gratings can form high sensibility sensors of small size, offering advantages over other systems with different technologies. This paper shows the development of an optical fiber gravimeter doped with Erbium that was characterized optically for loads going from 1 to 10 kg in a bandwidth between 1590nm to 1960nm, displaying a weight linear response against power. Later on this paper, the experimental results show that the previous described behavior can be modeled as characteristic function of the sensor.

  13. Piezoresistive boron doped diamond nanowire

    Energy Technology Data Exchange (ETDEWEB)

    Sumant, Anirudha V.; Wang, Xinpeng

    2017-07-04

    A UNCD nanowire comprises a first end electrically coupled to a first contact pad which is disposed on a substrate. A second end is electrically coupled to a second contact pad also disposed on the substrate. The UNCD nanowire is doped with a dopant and disposed over the substrate. The UNCD nanowire is movable between a first configuration in which no force is exerted on the UNCD nanowire and a second configuration in which the UNCD nanowire bends about the first end and the second end in response to a force. The UNCD nanowire has a first resistance in the first configuration and a second resistance in the second configuration which is different from the first resistance. The UNCD nanowire is structured to have a gauge factor of at least about 70, for example, in the range of about 70 to about 1,800.

  14. Green synthesis of boron doped graphene and its application as high performance anode material in Li ion battery

    Energy Technology Data Exchange (ETDEWEB)

    Sahoo, Madhumita; Sreena, K.P.; Vinayan, B.P.; Ramaprabhu, S., E-mail: ramp@iitm.ac.in

    2015-01-15

    Graphical abstract: Boron doped graphene (B-G), synthesized by simple hydrogen induced reduction technique using boric acid as boron precursor, have more uneven surface as a result of smaller bonding distance of boron compared to carbon, showed high capacity and high rate capability compared to pristine graphene as an anode material for Li ion battery application. - Abstract: The present work demonstrates a facile route for the large-scale, catalyst free, and green synthesis approach of boron doped graphene (B-G) and its use as high performance anode material for Li ion battery (LIB) application. Boron atoms were doped into graphene framework with an atomic percentage of 5.93% via hydrogen induced thermal reduction technique using graphite oxide and boric acid as precursors. Various characterization techniques were used to confirm the boron doping in graphene sheets. B-G as anode material shows a discharge capacity of 548 mAh g{sup −1} at 100 mA g{sup −1} after 30th cycles. At high current density value of 1 A g{sup −1}, B-G as anode material enhances the specific capacity by about 1.7 times compared to pristine graphene. The present study shows a simplistic way of boron doping in graphene leading to an enhanced Li ion adsorption due to the change in electronic states.

  15. Screening dynamics in doped titanates

    Energy Technology Data Exchange (ETDEWEB)

    Rubensson, J.E.; Luening, J.; Eisebitt, S. [Forschungszentrum Juelich (Germany)] [and others

    1997-04-01

    The time scale for carrier relaxation in semiconductors is on the same order of magnitude as the life time of shallow core hole states (a few femtoseconds). Resonant Inelastic soft X-ray scattering (RIXS) which involves (virtual) excitations of core levels consequently contains information about the time development of the electronic structure on this time scale. In many cases one can treat the scattering in an absorption (SXA) followed-by-emission (SXE) picture, where simply the rates for various processes can be compared with the intermediate core hole state decay rate as an internal {open_quotes}clock{close_quotes}. By variation of x (0 < x < 1) in La{sub x}Sr{sub 1{minus}x}TiO{sub 3}, the amount of Ti d electrons in the system can be controlled. SrTiO{sub 3} (x=0) is an insulator with an empty Ti d band. With increasing x, electrons are doped into the Ti d-band, and LaTiO{sub 3} (x=1) is a Mott Hubbard insulator with a Ti 3d{sup 1} configuration. In this work the authors demonstrate that the rate for Ti 2p core hole screening in La{sub x}Sr{sub 1{minus}x}TiO{sub 3} is doping dependent. The screening rate increases with the availability of Ti 3d electrons, and they estimate it to be 3.8 x 10{sup 13}/sec in La{sub 0.05}Sr{sub 0.95}TiO{sub 3}.

  16. Magnetic doping of a thiolated gold superatom

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Deen [ORNL; Whetten, Robert L [Georgia Institute of Technology

    2009-01-01

    The Au{sub 25}(SR){sub 18}{sup -} cluster is a new member in the superatom family which features a centered icosahedral shell (Au{sub 13}) protected by six RS(AuSR){sub 2} motifs (RS? being an alkylthiolate group). Here we show that this superatom can be magnetically doped by replacing the center Au atom with Cr, Mn, or Fe. We find that Cr- and Mn-doped clusters have an optimized magnetic moment of 5 Bohr magnetons while the Fe-doped cluster has an optimized magnetic moment of 3 Bohr magnetons. Although the dopant atom's local magnetic moment makes a major contribution to the total moment, the icosahedral Au{sub 12} shell is also found to be significantly magnetized. Our work here provides a scenario of magnetic doping of a metal-cluster superatom which is protected by ligands and made by wet chemistry.

  17. Semiconducting behavior of substitutionally doped bilayer graphene

    Science.gov (United States)

    Mousavi, Hamze; Khodadadi, Jabbar; Grabowski, Marek

    2018-02-01

    In the framework of the Green's functions approach, random tight-binding model and using the coherent potential approximation, electronic characteristics of the bilayer graphene are investigated by exploring various forms of substitutional doping of a single or both layers of the system by either boron and (or) nitrogen atoms. The results for displacement of the Fermi level resemble the behavior of acceptor or donor doping in a conventional semiconductor, dependent on the impurity type and concentration. The particular pattern of doping of just one layer with one impurity type is most efficient for opening a gap within the energy bands which could be tuned directly by impurity concentration. Doping both layers at the same time, each with one impurity type, leads to an anomaly whereby the gap decreases with increasing impurity concentration.

  18. The psychology behind doping in sport.

    Science.gov (United States)

    Ehrnborg, Christer; Rosén, Thord

    2009-08-01

    Drugs and methods to improve physical performance among athletes have been used since the beginning of sport history, but the use of performance enhancing drugs has not always been regarded as cheating. In short, the motives for doping are improving and maintaining physical functioning, coping with the social/psychological pressures and striving for social and psychological goals, including economic benefits. Factors such as, "doping dilemma", "win at all costs", cost versus benefit, and the specificity of some specific doping agents, also play major roles. It seems that action on the athletes' attitude about the achievement of physical improvement and creating effective methods to reveal the drug abuse, are two main ways in winning the struggle against doping.

  19. Superconductivity in carrier-doped silicon carbide

    Directory of Open Access Journals (Sweden)

    Takahiro Muranaka, Yoshitake Kikuchi, Taku Yoshizawa, Naoki Shirakawa and Jun Akimitsu

    2008-01-01

    Full Text Available We report growth and characterization of heavily boron-doped 3C-SiC and 6H-SiC and Al-doped 3C-SiC. Both 3C-SiC:B and 6H-SiC:B reveal type-I superconductivity with a critical temperature Tc=1.5 K. On the other hand, Al-doped 3C-SiC (3C-SiC:Al shows type-II superconductivity with Tc=1.4 K. Both SiC:Al and SiC:B exhibit zero resistivity and diamagnetic susceptibility below Tc with effective hole-carrier concentration n higher than 1020 cm−3. We interpret the different superconducting behavior in carrier-doped p-type semiconductors SiC:Al, SiC:B, Si:B and C:B in terms of the different ionization energies of their acceptors.

  20. Effects of Ni doping on photocatalytic activity of TiO2 thin films ...

    Indian Academy of Sciences (India)

    The TiO2 thin films doped by Ni uniformly and non-uniformly were prepared on glass substrate from an aqueous solution of ammonium hexa-fluoro titanate and NiF2 by liquid phase deposition technique. The addition of boric acid as an – scavenger will shift the equilibrium to one side and thereby deposition of the film is ...

  1. Photoelectrochemical reduction of carbon dioxide using Ge doped GaN nanowire photoanodes

    Directory of Open Access Journals (Sweden)

    Yichen Wang

    2015-11-01

    Full Text Available We report on the direct conversion of carbon dioxide (CO2 in a photoelectrochemical cell consisting of germanium doped gallium nitride nanowire anode and copper (Cu cathode. Various products including methane (CH4, carbon monoxide (CO, and formic acid (HCOOH were observed under light illumination. A Faradaic efficiency of ∼10% was measured for HCOOH. Furthermore, this photoelectrochemical system showed enhanced stability for 6 h CO2 reduction reaction on low cost, large area Si substrates.

  2. Hole transport in pure and doped hematite

    Science.gov (United States)

    Liao, Peilin; Carter, Emily A.

    2012-07-01

    Hematite (α-Fe2O3) is a promising candidate for use in photovoltaic (PV) and photoelectrochemical devices. Its poor conductivity is one major drawback. Doping hematite either p-type or n-type greatly enhances its measured conductivity and is required for potential p-n junctions in PVs. Here, we study hole transport in pure and doped hematite using an electrostatically embedded cluster model with ab initio quantum mechanics (unrestricted Hartree-Fock theory). Consistent with previous work, the model suggests that hole hopping is via oxygen anions for pure hematite. The activation energy for hole mobility is predicted to be at least 0.1 eV higher than the activation energy for electron mobility, consistent with the trend observed in experiments. We examine four dopants—magnesium(II), nickel(II), copper(II), and manganese(II/III) in direct cation substitution sites—to gain insight into the mechanism by which conductivity is improved. The activation energies are used to assess qualitative effects of different dopants. The hole carriers are predicted to be attracted to O anions near the dopants. The magnitude of the trapping effect is similar among the four dopants in their +2 oxidation states. The multivalent character of Mn doping facilitates local hole transport around Mn centers via a low-barrier O-Mn-O pathway, which suggests that higher hole mobility can be achieved with increasing Mn doping concentration, especially when a network of these low-barrier pathways is produced. Our results suggest that the experimentally observed conductivity increase in Mg-, Ni-, and Cu-doped p-type hematite is mostly due to an increase in hole carriers rather than improved mobility, and that Mg-, Ni-, and Cu-doping perform similarly, while the conductivity of Mn-doped hematite might be significantly improved in the high doping concentration limit.

  3. Thermal expansion of doped lanthanum gallates

    Indian Academy of Sciences (India)

    Thermal expansion of several compositions of Sr and Mg-doped LaGaO3 including an -site deficient composition (La0.9Sr0.1)0.98(Ga0.8Mg0.2)O2.821 were measured in the temperature range from 298 to 1273 K. The effect of doping on thermal expansion was studied by varying the composition at one site of the ...

  4. Porous Allograft Bone Scaffolds: Doping with Strontium

    Science.gov (United States)

    Zhao, Yantao; Guo, Dagang; Hou, Shuxun; Zhong, Hongbin; Yan, Jun; Zhang, Chunli; Zhou, Ying

    2013-01-01

    Strontium (Sr) can promote the process of bone formation. To improve bioactivity, porous allograft bone scaffolds (ABS) were doped with Sr and the mechanical strength and bioactivity of the scaffolds were evaluated. Sr-doped ABS were prepared using the ion exchange method. The density and distribution of Sr in bone scaffolds were investigated by inductively coupled plasma optical emission spectrometry (ICP-OES), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDS). Controlled release of strontium ions was measured and mechanical strength was evaluated by a compressive strength test. The bioactivity of Sr-doped ABS was investigated by a simulated body fluid (SBF) assay, cytotoxicity testing, and an in vivo implantation experiment. The Sr molar concentration [Sr/(Sr+Ca)] in ABS surpassed 5% and Sr was distributed nearly evenly. XPS analyses suggest that Sr combined with oxygen and carbonate radicals. Released Sr ions were detected in the immersion solution at higher concentration than calcium ions until day 30. The compressive strength of the Sr-doped ABS did not change significantly. The bioactivity of Sr-doped material, as measured by the in vitro SBF immersion method, was superior to that of the Sr-free freeze-dried bone and the Sr-doped material did not show cytotoxicity compared with Sr-free culture medium. The rate of bone mineral deposition for Sr-doped ABS was faster than that of the control at 4 weeks (3.28±0.23 µm/day vs. 2.60±0.20 µm/day; p<0.05). Sr can be evenly doped into porous ABS at relevant concentrations to create highly active bone substitutes. PMID:23922703

  5. Preparation of nitrogen-doped carbon tubes

    Science.gov (United States)

    Chung, Hoon Taek; Zelenay, Piotr

    2015-12-22

    A method for synthesizing nitrogen-doped carbon tubes involves preparing a solution of cyanamide and a suitable transition metal-containing salt in a solvent, evaporating the solvent to form a solid, and pyrolyzing the solid under an inert atmosphere under conditions suitable for the production of nitrogen-doped carbon tubes from the solid. Pyrolyzing for a shorter period of time followed by rapid cooling resulted in a tubes with a narrower average diameter.

  6. Porous allograft bone scaffolds: doping with strontium.

    Directory of Open Access Journals (Sweden)

    Yantao Zhao

    Full Text Available Strontium (Sr can promote the process of bone formation. To improve bioactivity, porous allograft bone scaffolds (ABS were doped with Sr and the mechanical strength and bioactivity of the scaffolds were evaluated. Sr-doped ABS were prepared using the ion exchange method. The density and distribution of Sr in bone scaffolds were investigated by inductively coupled plasma optical emission spectrometry (ICP-OES, X-ray photoelectron spectroscopy (XPS, and energy-dispersive X-ray spectroscopy (EDS. Controlled release of strontium ions was measured and mechanical strength was evaluated by a compressive strength test. The bioactivity of Sr-doped ABS was investigated by a simulated body fluid (SBF assay, cytotoxicity testing, and an in vivo implantation experiment. The Sr molar concentration [Sr/(Sr+Ca] in ABS surpassed 5% and Sr was distributed nearly evenly. XPS analyses suggest that Sr combined with oxygen and carbonate radicals. Released Sr ions were detected in the immersion solution at higher concentration than calcium ions until day 30. The compressive strength of the Sr-doped ABS did not change significantly. The bioactivity of Sr-doped material, as measured by the in vitro SBF immersion method, was superior to that of the Sr-free freeze-dried bone and the Sr-doped material did not show cytotoxicity compared with Sr-free culture medium. The rate of bone mineral deposition for Sr-doped ABS was faster than that of the control at 4 weeks (3.28 ± 0.23 µm/day vs. 2.60 ± 0.20 µm/day; p<0.05. Sr can be evenly doped into porous ABS at relevant concentrations to create highly active bone substitutes.

  7. Ultrasound assisted synthesis of iron doped TiO2catalyst.

    Science.gov (United States)

    Ambati, Rohini; Gogate, Parag R

    2018-01-01

    The present work deals with synthesis of Fe (III) doped TiO 2 catalyst using the ultrasound assisted approach and conventional sol-gel approach with an objective of establishing the process intensification benefits. Effect of operating parameters such as Fe doping, type of solvent, solvent to precursor ratio and initial temperature has been investigated to get the best catalyst with minimum particle size. Comparison of the catalysts obtained using the conventional and ultrasound assisted approach under the optimized conditions has been performed using the characterization techniques like DLS, XRD, BET, SEM, EDS, TEM, FTIR and UV-Vis band gap analysis. It was established that catalyst synthesized by ultrasound assisted approach under optimized conditions of 0.4mol% doping, irradiation time of 60min, propan-2-ol as the solvent with the solvent to precursor ratio as 10 and initial temperature of 30°C was the best one with minimum particle size as 99nm and surface area as 49.41m 2 /g. SEM analysis, XRD analysis as well as the TEM analysis also confirmed the superiority of the catalyst obtained using ultrasound assisted approach as compared to the conventional approach. EDS analysis also confirmed the presence of 4.05mol% of Fe element in the sample of 0.4mol% iron doped TiO 2 . UV-Vis band gap results showed the reduction in band gap from 3.2eV to 2.9eV. Photocatalytic experiments performed to check the activity also confirmed that ultrasonically synthesized Fe doped TiO 2 catalyst resulted in a higher degradation of Acid Blue 80 as 38% while the conventionally synthesized catalyst resulted in a degradation of 31.1%. Overall, the work has clearly established importance of ultrasound in giving better catalyst characteristics as well as activity for degradation of the Acid Blue 80 dye. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Boron-doped, carbon-coated SnO2/graphene nanosheets for enhanced lithium storage.

    Science.gov (United States)

    Liu, Yuxin; Liu, Ping; Wu, Dongqing; Huang, Yanshan; Tang, Yanping; Su, Yuezeng; Zhang, Fan; Feng, Xinliang

    2015-03-27

    Heteroatom doping is an effective method to adjust the electrochemical behavior of carbonaceous materials. In this work, boron-doped, carbon-coated SnO2 /graphene hybrids (BCTGs) were fabricated by hydrothermal carbonization of sucrose in the presence of SnO2/graphene nanosheets and phenylboronic acid or boric acid as dopant source and subsequent thermal treatment. Owing to their unique 2D core-shell architecture and B-doped carbon shells, BCTGs have enhanced conductivity and extra active sites for lithium storage. With phenylboronic acid as B source, the resulting hybrid shows outstanding electrochemical performance as the anode in lithium-ion batteries with a highly stable capacity of 1165 mA h g(-1) at 0.1 A g(-1) after 360 cycles and an excellent rate capability of 600 mA h g(-1) at 3.2 A g(-1), and thus outperforms most of the previously reported SnO2-based anode materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Enhanced Conductivity and Electrochemical Performance of Electrode Material Based on Multifunctional Dye Doped Polypyrrole.

    Science.gov (United States)

    Zang, Limin; Qiu, Jianhui; Yang, Chao; Sakai, Eiichi

    2016-03-01

    Polypyrrole were prepared via in-situ chemical oxidative polymerization in the presence of multisulfonate acid dye (acid violet 19). In this work, acid violet 19 could play the role as dopant, surfactant and physical cross-linker for pyrrole polymerization, and had impact on the morphology, dispersion stability, thermal stability, electrical conductivity and electrochemical behavior of the samples. The thermal stability of the dye doped polypyrrole was enhanced than pure polypyrrole due to the strong interactions between polypyrrole and acid violet 19. The dispersion stability of the samples in water was also improved by incorporating an appropriate amount of acid violet 19. The sample with 20% of acid violet 19 showed granular morphology with the smallest diameter of -50 nm and possessed the maximum electrical conductivity of 39.09 S/cm. The as-prepared multifunctional dye doped polypyrrole samples were used to fabricate electrodes and exhibited a mass specific capacitance of 379-206 F/g in the current density range of 0.2-1.0 A/g. The results indicated that the multifunctional dye could improve the performances of polypyrrole as electrode material for supercapacitors.

  10. CO tolerance by the PEMFC operational at temperatures up to 200°C

    DEFF Research Database (Denmark)

    Li, Qingfeng; He, Ronghuan; Gao, Ji-An

    2003-01-01

    The CO poisoning effect on carbon-supported platinum catalysts in polymer electrolyte membrane fuel cells has been investigated in a temperature range from 125 to 200°C with the phosphoric acid-doped polybenzimidazole membranes as electrolyte. The effect is very temperature-dependent and can be s...... densities lower than 0.25 A/cm2. For comparison, the tolerance is only 0.0025 % CO (25 ppm) at 80°C at current densities up to 0.15 A/cm². The effect of CO2 in hydrogen was also studied. At 175°C, 25% CO2 in the fuel stream showed only the dilution effect.......The CO poisoning effect on carbon-supported platinum catalysts in polymer electrolyte membrane fuel cells has been investigated in a temperature range from 125 to 200°C with the phosphoric acid-doped polybenzimidazole membranes as electrolyte. The effect is very temperature-dependent and can...... be sufficiently suppressed at elevated temperature. By defining a poisoning factor as less than 2% of power loss due to the poisoning effect, it is evaluated that 3% CO in hydrogen can be tolerated at current densities up to 0.7 A/cm2 at 200oC, while at 125oC 0.1% CO in hydrogen can be tolerated at current...

  11. Novel base doping profile for improved speed and power

    OpenAIRE

    Rehder, E. M.; Cismaru, C.; Zampardi, P. J.; Welser, R.E.

    2005-01-01

    We have experimentally studied the effect of twonewbase doping profiles on the base transit time of a GaAs npn heterojunction bipolar transistor. The doping in a region close to the collector is reduced either by a doping grade or a stepwise reduction. Quasi-electric fields resulting from these doping gradients increase the minority carrier velocity and the beta of large area transistors. By focusing these doping changes adjacent to the collector, the amount of low-doped base material and t...

  12. Thulium-doped optical fibers for fiber lasers

    Science.gov (United States)

    Kamrádek, M.; Aubrecht, J.; Peterka, P.; Podrazký, O.; Honzátko, P.; Cajzl, J.; Mrázek, J.; Kubeček, V.; Kašík, I.

    2017-12-01

    We present preparation and characterization of thulium-doped silica-based optical fibers for fiber lasers. The fibers were prepared by modified chemical vapor deposition process and doped with alumina and thulium ions. Alumina co-doping was achieved through two different methods - solution doping and nanoparticle doping method. Prepared preforms were characterized in terms of refractive index profiles and dopants distribution. For the drawn fibers, their spectral attenuation, fluorescence lifetime and laser performance were measured. In the case of nanoparticle doping, better laser characteristics were observed. Discussion and explanation of the trends for laser efficiency improvement is given.

  13. The redox behavior of potassium doped C60 peapods

    Science.gov (United States)

    Kalbáč, Martin; Kavan, Ladislav; Kataura, Hiromichi; Zukalová, Markéta; Dunsch, Lothar

    2004-09-01

    The redox behavior of fullerene peapods C60@SWCNT was studied by spectroelectrochemistry at samples chemically n-doped by K vapor. Strong chemical doping was proven by vanishing of the RBM mode and the downshift of TG mode in Raman spectroelectrochemistry. The K-doped peapods were subsequently studied electrochemically and thus n- and p-doped, respectively. The Ag(2) mode of intratubular fullerene in K-doped peapods contacting air was still red-shifted as referred to its position in a pristine peapod. An air-insensitive residual doping was found to be resistant also to cathodic charging. An explanation is given for this behavior.

  14. Chemical composition gratings in Germanium doped and Boron-Germanium co-doped fibers

    Science.gov (United States)

    Barrera, D.; Finazzi, V.; Coviello, G.; Bueno, A.; Sales, S.; Pruneri, V.

    2010-04-01

    We have successfully created Chemical Composition Gratings (CCGs) into two different types of fiber: standard telecommunications Germanium doped fibers and photosensitive Germanium/Boron co-doped fibers. We will present results on the regeneration process, the sensing properties and also the high temperature decay and maximum operative temperature for the CCGs created in both types of fiber.

  15. Al-doped and in-doped ZnO thin films in heterojunctions with silicon

    Energy Technology Data Exchange (ETDEWEB)

    Chabane, L.; Zebbar, N.; Kechouane, M. [LCMS, Faculty of Physics, University of Sciences and Technology (USTHB), BP 32-16111, Algiers (Algeria); Aida, M.S. [LCMet Interface, Faculty of Sciences, University of Constantine, 25000 (Algeria); Trari, M. [Laboratory of Storage and Valorization of Renewable Energies, Faculty of Chemistry (USTHB), BP 32-16111 Algiers (Algeria)

    2016-04-30

    The undoped, Al-doped and In-doped ZnO thin films were deposited by ultrasonic spray pyrolysis technique, onto glass and p-Si substrates and the physical properties of the films were investigated. The X-ray diffraction, optical analysis and electrical characterisations, indicate that the films were polycrystalline with hexagonal würtzite type structure and revealed that the aluminium doping deteriorates the crystalline and optical properties and enhances the electrical conductivity whereas indium doping improves all properties. The transport mechanism controlling the conduction through the heterojunctions was studied. For the heterostructures, the temperature dependent current–voltage characteristics showed rectifying behaviour in the dark, but current transport mechanism is not the same for all heterojunctions. Therefore, the presence of the interface states and volume defects are identified as limiting factors for obtaining a high quality heterojunction interface. - Highlights: • Al-doped and In-doped ZnO thin films have been deposited onto Si. • In-doped ZnO/p-Si heterojunction showed poor rectifying behaviour. • Al-doped ZnO/p-Si heterojunction showed a good rectifying at room temperature. • The carriers transport mechanisms was controlled by interfacial and volume defects.

  16. Visible Light-Photocatalytic Activity of Sulfate-Doped Titanium Dioxide Prepared by the Sol-Gel Method

    OpenAIRE

    Tsuneo Fujii; Hiromasa Nishikiori; Maki Hayashibe

    2013-01-01

    Sulfate-doped TiO2 was prepared from sol−gel systems containing titaniumalkoxide and sulfuric acid. The time needed for gelation of the systems was significantlyreduced by ultrasonic irradiation. The doped sulfate was observed by FTIR and XPSmeasurements. Some sulfate ions remained in the TiO2 even after heating at 300−600 °C.The UV and visible photocatalytic activities of the samples were confirmed by thedegradation of trichloroethylene (TCE). The activity of the photocatalyst samples during...

  17. High temperature polymer electrolyte membrane fuel cells: Approaches, status, and perspectives

    DEFF Research Database (Denmark)

    This book is a comprehensive review of high-temperature polymer electrolyte membrane fuel cells (PEMFCs). PEMFCs are the preferred fuel cells for a variety of applications such as automobiles, cogeneration of heat and power units, emergency power and portable electronics. The first 5 chapters...... of the book describe rationalization and illustration of approaches to high temperature PEM systems. Chapters 6 - 13 are devoted to fabrication, optimization and characterization of phosphoric acid-doped polybenzimidazole membranes, the very first electrolyte system that has demonstrated the concept...... of and motivated extensive research activity in the field. The last 11 chapters summarize the state-of-the-art of technological development of high temperature-PEMFCs based on acid doped PBI membranes including catalysts, electrodes, MEAs, bipolar plates, modelling, stacking, diagnostics and applications....

  18. Doping dependence of ordered phases and emergent quasiparticles in the doped Hubbard-Holstein model

    Science.gov (United States)

    Mendl, C. B.; Nowadnick, E. A.; Huang, E. W.; Johnston, S.; Moritz, B.; Devereaux, T. P.

    2017-11-01

    We present determinant quantum Monte Carlo simulations of the hole-doped single-band Hubbard-Holstein model on a square lattice, to investigate how quasiparticles emerge when doping a Mott insulator (MI) or a Peierls insulator (PI). The MI regime at large Hubbard interaction U and small relative e-ph coupling strength λ is quickly suppressed upon doping, by drawing spectral weight from the upper Hubbard band and shifting the lower Hubbard band towards the Fermi level, leading to a metallic state with emergent quasiparticles at the Fermi level. On the other hand, the PI regime at large λ and small U persists out to relatively high doping levels. We study the evolution of the d -wave superconducting susceptibility with doping, and find that it increases with lowering temperature in a regime of intermediate values of U and λ .

  19. Transport properties for carbon chain sandwiched between heteroatom-doped carbon nanotubes with different doping sites

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Wenjiang [Big Data and Information Engineering College of Guizhou University, Guiyang 550025 (China); Guizhou University of Finance and Economics, Guiyang 550025 (China); Deng, Xiaoqing, E-mail: xq-deng@163.com, E-mail: caish@mail.gufe.edu.cn [School of Physics and Electronic Science, Changsha University of Science and Technology, Changsha 410114 (China); Cai, Shaohong, E-mail: xq-deng@163.com, E-mail: caish@mail.gufe.edu.cn [Guizhou University of Finance and Economics, Guiyang 550025 (China)

    2016-07-15

    The First-principles calculation is used to investigate the transport properties of a carbon chain connected with N-and/or B-doped caped carbon nanotube acting as electrodes. The I-V curves of the carbon chain are affected by the N/B doping sites, and rectifying behavior can be obtained distinctly when the carbon chain is just connected onto two doping atom sites (N- chain-B), and a weak rectification occurs when N (B) doping at other sites. Interestingly, the spin-filtering effects exist in the junction when it is doped at other sites, undoped system, or N-terminal carbon chains. However, no this behavior is found in N-chain-B and B-chain-B systems. The analysis on the transmission spectra, PDOS, LDOS, spin density, and the electron transmission pathways give an insight into the observed results for the system.

  20. Hybrid Doping of Few-Layer Graphene via a Combination of Intercalation and Surface Doping

    KAUST Repository

    Mansour, Ahmed

    2017-05-23

    Surface molecular doping of graphene has been shown to modify its work function and increase its conductivity. However, the associated shifts in work function and increases in carrier concentration are highly coupled and limited by the surface coverage of dopant molecules on graphene. Here we show that few-layer graphene (FLG) can be doped using a hybrid approach, effectively combining surface doping by larger (metal-)organic molecules, while smaller molecules, such as Br2 and FeCl3, intercalate into the bulk. Intercalation tunes the carrier concentration more effectively, whereas surface doping of intercalated FLG can be used to tune its work function without reducing the carrier mobility. This multi-modal doping approach yields a very high carrier density and tunable work function for FLG, demonstrating a new versatile platform for fabricating graphene-based contacts for electronic, optoelectronic and photovoltaic applications.

  1. Rapid solid-phase microwave synthesis of highly photoluminescent nitrogen-doped carbon dots for Fe3+ detection and cellular bioimaging

    Science.gov (United States)

    He, Guili; Xu, Minghan; Shu, Mengjun; Li, Xiaolin; Yang, Zhi; Zhang, Liling; Su, Yanjie; Hu, Nantao; Zhang, Yafei

    2016-09-01

    Recently, carbon dots (CDs) have been playing an increasingly important role in industrial production and biomedical field because of their excellent properties. As such, finding an efficient method to quickly synthesize a large scale of relatively high purity CDs is of great interest. Herein, a facile and novel microwave method has been applied to prepare nitrogen doped CDs (N-doped CDs) within 8 min using L-glutamic acid as the sole reaction precursor in the solid phase condition. The as-prepared N-doped CDs with an average size of 1.64 nm are well dispersed in aqueous solution. The photoluminescence of N-doped CDs is pH-sensitive and excitation-dependent. The N-doped CDs show a strong blue fluorescence with relatively high fluorescent quantum yield of 41.2%, which remains stable even under high ionic strength. Since the surface is rich in oxygen-containing functional groups, N-doped CDs can be applied to selectively detect Fe3+ with the limit of detection of 10-5 M. In addition, they are also used for cellular bioimaging because of their high fluorescent intensity and nearly zero cytotoxicity. The solid-phase microwave method seems to be an effective strategy to rapidly obtain high quality N-doped CDs and expands their applications in ion detection and cellular bioimaging.

  2. Sectioned Core Doping Effect on Higher-Order Mode Amplification in Yb-Doped Rod-Type Photonic Crystal Fibers

    DEFF Research Database (Denmark)

    Poli, F.; Lægsgaard, Jesper; Passaro, D.

    2009-01-01

    The amplification properties of guided modes in Yb-doped rod-type photonic crystal fibers with sectioned core doping have been investigated, evaluating the doped-area radius which provides the effective suppression of both LP 11- and LP02-like modes.......The amplification properties of guided modes in Yb-doped rod-type photonic crystal fibers with sectioned core doping have been investigated, evaluating the doped-area radius which provides the effective suppression of both LP 11- and LP02-like modes....

  3. Synergistically enhanced activity of nitrogen-doped carbon dots/graphene composites for oxygen reduction reaction

    Science.gov (United States)

    Liu, Hui; Zhao, Qingshan; Liu, Jingyan; Ma, Xiao; Rao, Yuan; Shao, Xiaodong; Li, Zhongtao; Wu, Wenting; Ning, Hui; Wu, Mingbo

    2017-11-01

    With rapid dissociative adsorption of oxygen, nitrogen-doped carbon nanomaterials have been demonstrated to be efficient alternative catalysts for oxygen reduction reaction (ORR) in fuel cells. Herein, we developed a mild hydrothermal strategy to construct nitrogen-doped carbon dots/graphene (NCDs-NG) composites towards ORR. Carbon dots (CDs) were derived from petroleum coke via acid oxidation while graphene oxide (GO) was obtained from graphite by modified Hummer's method. Graphene was employed as a conductive substrate to disperse CDs during hydrothermal reducing reaction while ammonia was utilized as N source to dope both graphene and CDs. The synergistic effects, i.e. CDs as pillars for graphene and catalytic sites for ORR, the high conductivity of graphene, the quick O2 adsorption on doped pyridinic nitrogen endow the NCDs-NG composites with enhanced ORR catalytic performance in alkaline electrolyte. The onset potential of -95 mV and kinetic current density of 12.7 mA cm-2 at -0.7 V (vs. Ag/AgCl) can be compared to those of the commercial 20 wt% Pt/C catalyst. The electron transfer number is about 3.9, revealing a four-electron pathway for ORR. The optimal NCDs-NG catalyst shows superior durability and methanol tolerance than 20 wt% Pt/C. This work demonstrates a feasible and effective strategy to prepare metal-free efficient ORR electrocatalysts for fuel cell applications.

  4. Doping effects of surface functionalization on graphene with aromatic molecule and organic solvents

    Science.gov (United States)

    Wu, Guangfu; Tang, Xin; Meyyappan, M.; Lai, King Wai Chiu

    2017-12-01

    Aromatic molecule functionalization plays a key role in the development of graphene field-effect transistors (G-FETs) for bio-detection. We have investigated the doping effects of surface functionalization and its influence on the carrier mobility of graphene. The aromatic molecule (1-pyrenebutanoic acid succinimidyl ester, PBASE), which is widely used as a linker to anchor bio-probes, was employed here to functionalize graphene. Dimethyl formamide (DMF) and methanol (CH3OH) were used as two solvents to dissolve PBASE. Raman spectra showed that both PBASE and these two solvents imposed doping effects on graphene. The PBASE was stably immobilized on the graphene surface, which was confirmed by the new peak at around 1623.5 cm-1 and the disordered D peak at 1350 cm-1. Electrical measurements and Fermi level shift analysis further revealed that PBASE imposes a p-doping effect while DMF and CH3OH impose an n-doping effect. More importantly, CH3OH causes a smaller reduction in the carrier mobility of G-FETs (from 1095.6 cm2/V s to 802.4 cm2/V s) than DMF (from 1640.4 cm2/V s to 5.0 cm2/V s). Therefore, CH3OH can be regarded as a better solvent for the PBASE functionalization. This careful study on the influence of organic solvents on graphene during PBASE functionalization process provides an effective approach to monitor the surface functionalization of graphene.

  5. Effect of Er doping on the structural and magnetic properties of cobalt-ferrite

    Energy Technology Data Exchange (ETDEWEB)

    Prathapani, Sateesh; Vinitha, M.; Das, D., E-mail: ddse@uohyd.ernet.in [School of Engineering Sciences and Technology, University of Hyderabad, Hyderabad 500046 (India); Jayaraman, T. V. [Department of Mechanical and Materials Engineering, University of Nebraska, Lincoln, Nebraska 68588 (United States)

    2014-05-07

    Nanocrystalline particulates of Er doped cobalt-ferrites CoFe{sub (2−x)}Er{sub x}O{sub 4} (0 ≤ x ≤ 0.04), were synthesized, using sol-gel assisted autocombustion method. Co-, Fe-, and Er- nitrates were the oxidizers, and malic acid served as a fuel and chelating agent. Calcination (400–600 °C for 4 h) of the precursor powders was followed by sintering (1000 °C for 4 h) and structural and magnetic characterization. X-ray diffraction confirmed the formation of single phase of spinel for the compositions x = 0, 0.01, and 0.02; and for higher compositions an additional orthoferrite phase formed along with the spinel phase. Lattice parameter of the doped cobalt-ferrites was higher than that of pure cobalt-ferrite. The observed red shift in the doped cobalt-ferrites indicates the presence of induced strain in the cobalt-ferrite matrix due to large size of the Er{sup +3} compared to Fe{sup +3}. Greater than two-fold increase in coercivity (∼66 kA/m for x = 0.02) was observed in doped cobalt-ferrites compared to CoFe{sub 2}O{sub 4} (∼29 kA/m)

  6. Synthesis and Doping of Silicon Nanocrystals for Versatile Nanocrystal Inks

    Science.gov (United States)

    Kramer, Nicolaas Johannes

    atmospheric pressures necessitates high plasma densities to reach temperatures required for crystallization of nanoparticles. Using experimentally determined plasma properties from the literature, the model estimates the nanoparticle temperature that is achieved during synthesis at atmospheric pressures. It was found that temperatures well above those required for crystallization can be achieved. Now that the synthesis of nanocrystals is understood, the second half of this thesis will focus on doping of the nanocrystals. The doping of semiconductor nanocrystals, which is vital for the optimization of nanocrystal-based devices, remains a challenge. Gas phase plasma approaches have been very successful in incorporating dopant atoms into nanocrystals by simply adding a dopant precursor during synthesis. However, little is known about the electronic activation of these dopants. This was investigated with field-effect transistor measurements using doped silicon nanocrystal films. It was found that, analogous to bulk silicon, boron and phosphorous electronically dope silicon nanocrystals. However, the dopant activation efficiency remains low as a result of self-purification of the dopants to the nanocrystal surface. Next the plasmonic properties of heavily doped silicon nanocrystals was explored. While the synthesis method was identical, the plasmonic behavior of phosphorus-doped and boron-doped nanocrystals was found the be significantly different. Phosphorus-doped nanocrystals exhibit a plasmon resonance immediately after synthesis, while boron-doped nanocrystals require a post-synthesis annealing or oxidation treatment. This is a result of the difference in dopant location. Phosphorus is more likely to be incorporated into the core of the nanocrystal, while the majority of boron is placed on the surface of the nanocrystal. The oxidized boron-doped particles exhibit stable plasmonic properties, and therefore this allows for the production of air-stable silicon-based plasmonic

  7. Boron-Doped Diamond Electrode in Sodium Sulphate Medium

    Directory of Open Access Journals (Sweden)

    Codruţa Cofan

    2011-01-01

    Full Text Available Differential pulse voltammetry (DPV and chronoamperometry (CA were used to detect and determine acetylsalicylic acid (ASA at a mildly oxidized boron-doped diamond (BDD electrode in a neutral sodium sulphate solution as supporting electrolyte. ASA determination in unbuffered medium was achieved using neutralized standard and real samples. Over the concentration range of 0.01 mM–0.1 mM, linear calibration plots of anodic current peaks in DPV and anodic currents in CA experiments versus concentration were obtained with very high correlation coefficients and good sensitivity values. The limits of detection were situated around 1 μM. The association of DPV and CA techniques with standard addition method represented a suitable option for the determination of ASA in real samples such as pharmaceutical formulations.

  8. Fabrication of Pd Doped WO3 Nanofiber as Hydrogen Sensor

    Directory of Open Access Journals (Sweden)

    Alireza Nikfarjam

    2013-01-01

    Full Text Available Pd doped WO3 fibers were synthesized by electro-spinning. The sol gel method was employed to prepare peroxopolytungstic acid (P-PTA. Palladium chloride and Polyvinyl pyrrolidone (PVP was dissolved in the sol Pd:WO3 = 10% molar ratio. The prepared sol was loaded into a syringe connected to a high voltage of 18.3 kV and electrospun fibers were collected on the alumina substrates. Scanning electron microscope (SEM, X-ray powder diffraction (XRD and X-ray photoelectron spectroscopy (XPS techniques were used to analyze the crystal structure and chemical composition of the fibers after heat treatment at 500 °C. Resistance-sensing measurements exhibited a sensitivity of about 30 at 500 ppm hydrogen in air, and the response and recovery times were about 20 and 30 s, respectively, at 300 °C. Hydrogen gas sensing mechanism of the sensor was also studied.

  9. Influences of glycerol as an efficient doping agent on crystal structure and antibacterial activity of B-TiO2 nano-materials.

    Science.gov (United States)

    Yang, He; Wang, Yuzheng; Xue, Xiangxin

    2014-10-01

    In this study, highly effective boron acid and glycerol co-doped TiO2 nano-materials were directly synthesized via a sol-gel method. The resulting materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectrum (FT-IR), UV-vis diffuse reflectance spectroscopy (DRS) and X-ray photoelectron (PL) spectroscopy. The results indicate that boron dopant is partially embedded into the interstitial TiO2 structure or incorporated into the TiO2 lattice through occupying the position of the oxygen atom, and others is present in the form of B2O3. Boron acid and glycerol co-doping TiO2 materials show obvious red shift in their absorption edges and efficient electron-hole separation because of the glycerol doping. The study on the antibacterial activities demonstrate that co-doped TiO2 nano-materials could effectively inactivate the bacteria under visible light irradiation. Co-doped TiO2 nano-materials exhibit more excellent antibacterial performance than B-doped TiO2 nano-materials. Copyright © 2014 Elsevier B.V. All rights reserved.

  10. Growth hormone doping: a review

    Directory of Open Access Journals (Sweden)

    Erotokritou-Mulligan I

    2011-07-01

    Full Text Available Ioulietta Erotokritou-Mulligan, Richard IG Holt, Peter H SönksenDevelopmental Origins of Health and Disease Division, University of Southampton School of Medicine, The Institute of Developmental Science, Southampton General Hospital, Southampton, UKAbstract: The use of growth hormone (GH as a performance enhancing substance was first promoted in lay publications, long before scientists fully acknowledged its benefits. It is thought athletes currently use GH to enhance their athletic performance and to accelerate the healing of sporting injuries. Over recent years, a number of high profile athletes have admitted to using GH. To date, there is only limited and weak evidence for its beneficial effects on performance. Nevertheless the “hype” around its effectiveness and the lack of a foolproof detection methodology that will detect its abuse longer than 24 hours after the last injection has encouraged its widespread use. This article reviews the current evidence of the ergogenic effects of GH along with the risks associated with its use. The review also examines methodologies, both currently available and in development for detecting its abuse.Keywords: performance enhancing substance, GH, doping in sport, detection methods

  11. Lanthanide-doped luminescent ionogels.

    Science.gov (United States)

    Lunstroot, Kyra; Driesen, Kris; Nockemann, Peter; Van Hecke, Kristof; Van Meervelt, Luc; Görller-Walrand, Christiane; Binnemans, Koen; Bellayer, Séverine; Viau, Lydie; Le Bideau, Jean; Vioux, André

    2009-01-14

    Ionogels are solid oxide host networks confining at a meso-scale ionic liquids, and retaining their liquid nature. Ionogels were obtained by dissolving lanthanide(III) complexes in the ionic liquid 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C6mim][Tf2N], followed by confinement of the lanthanide-doped ionic liquid mixtures in the pores of a nano-porous silica network. [C6mim][Ln(tta)4], where tta is 2-thenoyltrifluoroacetonate and Ln=Nd, Sm, Eu, Ho, Er, Yb, and [choline]3[Tb(dpa)3], where dpa=pyridine-2,6-dicarboxylate (dipicolinate), were chosen as the lanthanide complexes. The ionogels are luminescent, ion-conductive inorganic-organic hybrid materials. Depending on the lanthanide(III) ion, emission in the visible or the near-infrared regions of the electromagnetic spectrum was observed. The work presented herein highlights that the confinement did not disturb the first coordination sphere of the lanthanide ions and also showed the excellent luminescence performance of the lanthanide tetrakis beta-diketonate complexes. The crystal structures of the complexes [C6mim][Yb(tta)4] and [choline]3[Tb(dpa)3] are reported.

  12. Effect of aluminum and yttrium doping on zinc sulphide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Swati, E-mail: sharma.swati1507@gmail.com; Kashyap, Jyoti; Kapoor, A. [Department of Electronic Science, University of Delhi South Campus, Benito Juarez Road, New Delhi-110021 (India); Gupta, Shubhra [Sri Venkateswara College, University of Delhi, New Delhi-110021 (India); Natasha [Maharaja Agrasen College, University of Delhi-110053 (India)

    2016-05-06

    In this work, pristine and doped Zinc Sulphide (ZnS) nanoparticles have been synthesized via chemical co-precipitation method. ZnS nanoparticles have been doped with Aluminium (Al) and Yttrium (Y) with doping concentration of 5wt% each. The structural and optical properties of the as prepared nanoparticles have been studied using X-Ray diffraction (XRD) technique and Photoluminescence spectroscopy. Average grain size of 2-3nm is observed through the XRD analysis. Effect of doping on stress, strain and lattice constant of the nanoparticles has also been analyzed. Photoluminescence spectra of the as prepared nanoparticles is enhanced due to Al doping and quenched due to Y doping. EDAX studies confirm the relative doping percentage to be 3.47 % and 3.94% by wt. for Al and Y doped nanoparticles respectively. Morphology of the nanoparticles studied using TEM and SEM indicates uniform distribution of spherical nanoparticles.

  13. Metal contacts to lowly doped Si and ultra thin SOI

    NARCIS (Netherlands)

    Rajasekharan, B.; Salm, Cora; Hueting, Raymond Josephus Engelbart; Wolters, Robertus A.M.; Schmitz, Jurriaan

    2009-01-01

    We present our investigations on the fabrication of ohmic and pchottky contacts of several metals on lowly doped bulk pi and plf wafers. qhrough this paper we evaluate the fabrication of rectifying devices in which no doping is intentionally introduced.

  14. Tuning the Emission Energy of Chemically Doped Graphene Quantum Dots

    National Research Council Canada - National Science Library

    Noor-Ul-Ain; Eriksson, Martin; Schmidt, Susann; Asghar, M; Lin, Pin-Cheng; Holtz, Per; Syväjärvi, Mikael; Yazdi, G

    2016-01-01

    .... Photoluminescence data obtained from (Cl- and N-doped) GQDs and (B-, Na-, and K-doped) GQDs, respectively exhibited red- and blue-shift with respect to the photoluminescence of the undoped GQDs...

  15. Effect of aluminum and yttrium doping on zinc sulphide nanoparticles

    Science.gov (United States)

    Sharma, Swati; Kashyap, Jyoti; Gupta, Shubhra; Natasha, Kapoor, A.

    2016-05-01

    In this work, pristine and doped Zinc Sulphide (ZnS) nanoparticles have been synthesized via chemical co-precipitation method. ZnS nanoparticles have been doped with Aluminium (Al) and Yttrium (Y) with doping concentration of 5wt% each. The structural and optical properties of the as prepared nanoparticles have been studied using X-Ray diffraction (XRD) technique and Photoluminescence spectroscopy. Average grain size of 2-3nm is observed through the XRD analysis. Effect of doping on stress, strain and lattice constant of the nanoparticles has also been analyzed. Photoluminescence spectra of the as prepared nanoparticles is enhanced due to Al doping and quenched due to Y doping. EDAX studies confirm the relative doping percentage to be 3.47 % and 3.94% by wt. for Al and Y doped nanoparticles respectively. Morphology of the nanoparticles studied using TEM and SEM indicates uniform distribution of spherical nanoparticles.

  16. Visible Light-Photocatalytic Activity of Sulfate-Doped Titanium Dioxide Prepared by the Sol−Gel Method

    Directory of Open Access Journals (Sweden)

    Tsuneo Fujii

    2013-04-01

    Full Text Available Sulfate-doped TiO2 was prepared from sol−gel systems containing titaniumalkoxide and sulfuric acid. The time needed for gelation of the systems was significantlyreduced by ultrasonic irradiation. The doped sulfate was observed by FTIR and XPSmeasurements. Some sulfate ions remained in the TiO2 even after heating at 300−600 °C.The UV and visible photocatalytic activities of the samples were confirmed by thedegradation of trichloroethylene (TCE. The activity of the photocatalyst samples duringthe UV irradiation strongly depended on their crystallinities rather than their specificsurface areas, i.e., adsorption ability. The degradation rate during the visible irradiationdepended on both the adsorption ability and visible absorption of the photocatalystsamples. The visible absorption induced by the sulfate-doping was effective for theTCE degradation.

  17. Synthesis and Characterization of Eu3+-Doped CdS Quantum Dots by a Single-Step Aqueous Method.

    Science.gov (United States)

    Zhou, Chunyan; Song, Jiahui; Zhang, Xinguo; Sun, Lu; Zhou, Liya; Huang, Ni; Gan, Yufei; Chen, Mengyang; Zhang, Wei

    2016-04-01

    Eu3+-doped CdS quantum dots (QDs) are successfully synthesized through a straightforward single-pot process in aqueous solution using thioglycolic acid as the capping ligand. The structure, shape, and spectral properties of the QDs are investigated. The obtained CdS:Eu3+ QDs exhibit cubic structures with good crystallinity and approximately sphere-like shapes about 4 nm in diameter. The CdS QDs manifest a broadband emission peak at 600 nm and enhanced Photoluminescence (PL) emission intensity after doping with Eu3+ ions. Given the strong PL intensity and good chromaticity of the sulfide-based QDs, they have potential use in doping rare-earth ions.

  18. Erbium doped stain etched porous silicon

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Diaz, B. [Departamento de Fisica Basica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Diaz-Herrera, B. [Departamento de Energia Fotovoltaica, Instituto Tecnologico de Energias Renovables (ITER), Poligono Industrial de Granadilla, 38611 S/C Tenerife (Spain); Guerrero-Lemus, R. [Departamento de Fisica Basica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain)], E-mail: rglemus@ull.es; Mendez-Ramos, J.; Rodriguez, V.D. [Departamento de Fisica Fundamental, Experimental Electronica y Sistemas, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Hernandez-Rodriguez, C. [Departamento de Fisica Basica, Universidad de La Laguna, Avda. Astrofisico Francisco Sanchez, 38204 La Laguna, S/C de Tenerife (Spain); Martinez-Duart, J.M. [Departamento de Fisica Aplicada, C-XII, Universidad Autonoma de Madrid, 28049 Cantoblanco, Madrid (Spain)

    2008-01-15

    In this work a simple erbium doping process applied to stain etched porous silicon layers (PSLs) is proposed. This doping process has been developed for application in porous silicon solar cells, where conventional erbium doping processes are not affordable because of the high processing cost and technical difficulties. The PSLs were formed by immersion in a HF/HNO{sub 3} solution to properly adjust the porosity and pore thickness to an optimal doping of the porous structure. After the formation of the porous structure, the PSLs were analyzed by means of nitrogen BET (Brunauer, Emmett and Teller) area measurements and scanning electron microscopy. Subsequently, the PSLs were immersed in a saturated erbium nitrate solution in order to cover the porous surface. Then, the samples were subjected to a thermal process to activate the Er{sup 3+} ions. Different temperatures and annealing times were used in this process. The photoluminescence of the PSLs was evaluated before and after the doping processes and the composition was analyzed by Fourier transform IR spectroscopy.

  19. Blood doping at the Olympic Games.

    Science.gov (United States)

    Fitch, Kenneth D

    2017-11-01

    The objective of this paper was to review our knowledge of athletes who have, are believed to have or have attempted to engage in blood doping to enhance their performance at an Olympic Games. The paper focused on the Games from Munich 1972 to London 2012 and the author had a medical role at each of the Olympics that is discussed. The study revealed that Olympic athletes have benefitted from manipulating their blood by re-infusion of autologous or infusion of homologous blood and by administering erythropoiesis stimulating agents, notably the three generations of erythropoietins. Fifty seven athletes have been sanctioned with 12 athletes forfeiting 17 Olympic medals including 12 gold medals because of blood doping. Until 1986, the infusion of blood was not prohibited in sport but considered unethical. Erythropoietin was prohibited by the International Olympic Committee's Medical Commission in 1990. There has been a change as to how Olympic athletes have enhanced performance by blood doping, commencing with blood infusion and later administering erythropoiesis stimulating agents and significant advances have occurred in detecting such misuse. Currently, the hematological component of World Anti-Doping Agency's athlete biological passport is an important but not infallible mechanism to identify athletes who cheat by blood doping.

  20. Hole-doped cuprate high temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Chu, C.W.; Deng, L.Z.; Lv, B.

    2015-07-15

    Highlights: • Historical discoveries of hole-doped cuprates and representative milestone work. • Several simple and universal scaling laws of the hole-doped cuprates. • A comprehensive classification list with references for hole-doped cuprates. • Representative physical parameters for selected hole-doped cuprates. - Abstract: Hole-doped cuprate high temperature superconductors have ushered in the modern era of high temperature superconductivity (HTS) and have continued to be at center stage in the field. Extensive studies have been made, many compounds discovered, voluminous data compiled, numerous models proposed, many review articles written, and various prototype devices made and tested with better performance than their nonsuperconducting counterparts. The field is indeed vast. We have therefore decided to focus on the major cuprate materials systems that have laid the foundation of HTS science and technology and present several simple scaling laws that show the systematic and universal simplicity amid the complexity of these material systems, while referring readers interested in the HTS physics and devices to the review articles. Developments in the field are mostly presented in chronological order, sometimes with anecdotes, in an attempt to share some of the moments of excitement and despair in the history of HTS with readers, especially the younger ones.

  1. Current Status of Doping in Japan Based on Japan Anti-Doping Disciplinary Panels of the Japan Anti-Doping Agency (JADA): A Suggestion on Anti-Doping Activities by Pharmacists in Japan.

    Science.gov (United States)

    Imanishi, Takashi; Kawabata, Takayoshi; Takayama, Akira

    2017-01-01

    In 2009, the Japan Anti-Doping Agency (JADA) established the "Sports Pharmacist Accreditation Program" to prevent doping in sports. Since then, anti-doping activities in Japan have been attracting attention. In this study, we investigated research about the current status of doping from 2007 to 2014 in Japan to make anti-doping activities more concrete, and we also discussed future anti-doping activities by pharmacists. In Japan, bodybuilding was the sporting event with the highest number and rate of doping from 2007 to 2014. Many of the positive doping cases were detected for class S1 (anabolic agents), S5 (diuretics and masking agents), and S6 (stimulants). Within class S1, supplements were the main cause of positive doping. Within class S5, medicines prescribed by medical doctors were the main cause of positive doping. Within class S6, non-prescription medicines (e.g., OTC) were the main cause of positive doping. When we looked at the global statistics on doping, many of the positive doping cases were detected for class S1. On comparing the Japanese statistics with the global statistics, the rate of positive doping caused by class S1 was significantly lower, but that caused by classes S5 and S6 was significantly higher in Japan than in the world. In conclusion, pharmacists in Japan should pay attention to class S1, S5, and S6 prohibited substances and to the sport events of bodybuilding. Based on this study, sports pharmacists as well as common pharmacists should suggest new anti-doping activities to prevent doping in the future.

  2. A zinc chloride-doped adhesive facilitates sealing at the dentin interface: A confocal laser microscopy study.

    Science.gov (United States)

    Toledano, Manuel; Osorio, Raquel; Osorio, Estrella; Cabello, Inmaculada; Toledano-Osorio, Manuel; Aguilera, Fátima S

    2017-10-01

    The aim of this study was to ascertain the effect of Zn-doping of dental adhesives and mechanical load cycling on the micromorphology of the resin-dentin interdiffusion zone (of sound and caries affected dentin). The investigation considered two different Zn-doped adhesive approaches and evaluated the interface using a doubled dye fluorescent technique and a calcium chelator fluorophore under a confocal laser scanning microscopy. Sound and carious dentin-resin interfaces of unloaded specimens were deficiently resin-hybridized, in general. These samples showed a rhodamine B-labeled hybrid layer and adhesive layer completely affected by fluorescein penetration (nanoleakage) through the porous resin-dentin interface. It was thicker after phosphoric acid-etching and more extended in carious dentin. Zn-doping promoted an improved sealing of the resin-dentin interface, a decrease of the hybrid layer porosity, and an increment of dentin mineralization. Load cycling augmented the sealing of the Zn-doped resin-dentin interfaces, as porosity and nanoleakage diminished, and even disappeared in caries-affected dentin substrata conditioned with EDTA. Sound and carious dentin specimens analyzed with the xylenol orange technique produced a clearly outlined fluorescence when resins were Zn-doped, due to a consistent Ca-mineral deposition within the bonding interface and inside the dentinal tubules. It was more evident when load cycling was applied on specimens treated with self-etching adhesives that were Zn-doped. Micropermeability at the resin-dentin interface diminished after combining EDTA pretreatment, ZnCl 2 -doping and mechanical loading stimuli on restorations. It is clearly preferable to include the zinc compounds into the bonding constituents of the self-etching adhesives, instead of into the primer ingredients. The promoted new mineral segments contributed to reduce or avoid both porosity and nanoleakage from the load cycled Zn-doped resin dentin interfaces. EDTA

  3. Synthesis of Doped and non-Doped Nano MgO Ceramic Membranes

    Directory of Open Access Journals (Sweden)

    Shiraz Labib

    2013-12-01

    Full Text Available Doped and non-doped MgO coated thin films on alumina substrates were prepared using a chelating sol-gel method under controlled conditions to prepare nanomaterials with unprecedented properties. The effect of doping of ZnO on thermal, surface and structural properties was investigated using DTA-TG, BET and XRD respectively. Also microstructural studies and coating thickness measurements of MgO thin film were conducted using SEM. An increase in the thermal stability of MgO with increasing ZnO doping percent was observed. The increase of ZnO doping percent showed a marked decrease in the average particle size of MgO powder as a result of the replacement of some Mg2+ by Zn2+ which has similar ionic radius as Mg2+. This decrease in particle size of MgO was also related to the decrease of the degree of MgO crystalinity. The increase of ZnO doping also showed a marked decrease in coating thickness values of the prepared membranes. This decrease was related to the  mechanism of ZnO doping into a MgO crystal lattice.

  4. Changes in the structure of doped poly aniline (Pani-HCL) due to the process of de-doped;Alteracos na estrutura da polianilina dopada (PAni-HCL) devido ao processo de desdopagem

    Energy Technology Data Exchange (ETDEWEB)

    Gomes, Everton Carlos; Oliveira, Maria Auxiliadora Silva de, E-mail: evertonquimica@gmail.co [Instituto Tecnologico da Aeronautica (ITA), Sao Jose dos Campos, SP (Brazil). Dept. de Engenharia Mecanica e Aeronautica. Lab. de Estudos de Corrosao

    2009-07-01

    The poly aniline (PAni) is much studied, partly due to its relatively ease chemical or electrochemical synthesis, thermal stability in air and redox behavior. The chemical synthesis of poly aniline (PAni) was performed in a medium containing hydrochloric acid (HCl) as a doping agent. After that, the obtained polymer was de-doped in alkaline medium (NH4OH). Thermogravimetric analysis (TG) showed that the doped polymer, PAni-HCl, shows better thermal stability in comparison with the de-doped polymer (PAni-NH4OH). Differential scanning calorimetry (DSC) analyses show that the number of processes occurring during the heating of the polymer, as well as the complexity of them, is much higher in the PAni-HCl than the in the PAni-NH4OH. Through the spectra of FTIR and Raman could conclude that dedoping PAni-HCl was not complete, but the degree of doping of PAni-NH4OH decreased by treatment with ammonium hydroxide. XRD analysis pointed out that as the PAni-HCl as the PAni-NH4OH are partially crystalline. (author)

  5. Attitudes and doping: a structural equation analysis of the relationship between athletes' attitudes, sport orientation and doping behaviour

    National Research Council Canada - National Science Library

    Petróczi, Andrea

    2007-01-01

    .... Traditional behavioural models assume that the behaviour in question is the ultimate end. However, growing evidence suggests that in doping situations, the doping behaviour is not the end but a means to an end, which is gaining competitive advantage...

  6. Effects of Bi doping on dielectric and ferroelectric properties of ...

    Indian Academy of Sciences (India)

    Effects of Bi doping on structure, dielectric and ferroelectric properties of PLBZT were investigated. Bi doping is useful in crystallization of PLBZT films and promoting grain growth. When the Bi-doping content is not more than 0.4, an obvious improvement in dielectric properties and leakage current of PLBZT was confirmed ...

  7. Preparation of Sm doped cerium dioxide film by anodization

    Science.gov (United States)

    LIU, Xiaozhen; Yang, Junhua; Liu, Xiaozhou; Xia, Letian; Chen, Jie; Zhu, Ying

    2017-04-01

    The Sm doped cerium dioxide films were prepared with cerium foils as raw materials by anodization in Sm(NO3)3-Na2C2O4-NH3·H2O-H2O-(CH2OH)2 electrolyte. The anodic Sm doped cerium oxide film was heat treated at 550°C. The Sm doped cerium dioxide films were characterized with X-ray diffraction (XRD), energy-dispersive analyses of X-ray (EDAX), Fourier transform infrared (FTIR) techniques and scanning electron microcopy (SEM), respectively. The anodic Sm doped cerium oxide film is semi crystalline film. The heat treated anodic Sm doped cerium oxide film at 550°C has a structure of cubic fluorite. The doping of Sm is replacement doping or caulking doping. The Sm doped cerium dioxide film is porous film. The water, ethylene glycol and CO2 are adsorbed in the anodic Sm doped cerium oxide film. The adsorbing water, ethylene glycol and CO2 in the anodic Sm doped cerium oxide film are removed at 550°C. The Sm doped cerium dioxide film has strong absorption in the range of 1200 ~ 4000cm-1.

  8. Monolithic thulium-doped fiber laser

    Science.gov (United States)

    Aubrecht, J.; Peterka, P.; Honzátko, P.; Todorov, F.; Podrazký, O.; Kamrádek, M.; Proboštová, J.; Kašík, I.

    2017-12-01

    In this contribution we report and discuss the results of laser characterizations of experimental thulium-doped optical fibers. These active fibers were fabricated in house and were tested in two laser systems to verify their characteristics. The first one, a monolithic fiber laser, was of great interest to us due to its potentially lower overall resonator losses, improved laser lifetime and better robustness. The compact laser cavities with a Bragg gratings inscribed directly into the active optical fiber differs to the second laser system where the Bragg gratings were inscribed into a passive fiber which had to be spliced to the active fiber. The tested fibers were manufactured by the modified chemical vapor deposition method and a solution-doping of thulium ions with Al2O3 or alumina nanoparticles, respectively. We focused on comparison of laser output powers, slope efficiencies, and laser thresholds for particular thulium-doped fiber in different laser configurations.

  9. The moral disengagement in doping scale

    DEFF Research Database (Denmark)

    Kavussanu, Maria; Hatzigeorgiadis, Antonis; Elbe, Anne-Marie

    2016-01-01

    Statement of Problem The use of banned substances to enhance performance occurs in sport. Therefore, developing valid and reliable instruments that can predict likelihood to use banned substances is important. Method We conducted three studies. In Study 1, football players (N = 506) and athletes...... to use a banned substance in a hypothetical situation. Results The results of Study 1 showed that one-factor model fitted the data well, and the scale showed measurement invariance across males and females. In Study 2, we provided evidence for convergent, concurrent, discriminant, and predictive validity...... from a variety of team sports (N = 398) completed the Moral Disengagement in Doping Scale (MDDS). In Study 2, team sport athletes (N = 232) completed the MDDS and questionnaires measuring moral disengagement in sport, doping attitudes, moral identity, antisocial sport behavior, situational doping...

  10. Doping monolayer graphene with single atom substitutions

    KAUST Repository

    Wang, Hongtao

    2012-01-11

    Functionalized graphene has been extensively studied with the aim of tailoring properties for gas sensors, superconductors, supercapacitors, nanoelectronics, and spintronics. A bottleneck is the capability to control the carrier type and density by doping. We demonstrate that a two-step process is an efficient way to dope graphene: create vacancies by high-energy atom/ion bombardment and fill these vacancies with desired dopants. Different elements (Pt, Co, and In) have been successfully doped in the single-atom form. The high binding energy of the metal-vacancy complex ensures its stability and is consistent with in situ observation by an aberration-corrected and monochromated transmission electron microscope. © 2011 American Chemical Society.

  11. Psychogenic urine retention during doping controls

    DEFF Research Database (Denmark)

    Elbe, Anne-Marie; Schlegel, Marius M.; Brand, Ralf

    2012-01-01

    Psychogenic urine retention during doping controls (PURD) refers to an athlete's inability to urinate during a doping control. This paper reports PURD to occur quite frequently in elite athletes, investigates the relationship to the clinical disorder of paruresis (PAR), and investigates its...... relation to recovery, performance, and self-perception of professionalism and athletic excellence. Furthermore, a scale developed especially for the close description and measurement of PURD is presented. A questionnaire was used for measuring paruresis. The results are based on two online and one paper...... and pencil study involving 222 German-speaking athletes from various sports. The results indicate that 60% of these athletes have experienced psychogenic urine retention during doping controls, with only 39% of them showing symptoms of paruresis. PURD impacts athlete recovery and self...

  12. [The fight against doping: today and tomorrow].

    Science.gov (United States)

    Rieu, Michel

    2004-01-01

    Since Antiquity, sport persons have used doping methods to improve their performance. The methods used today are increasingly specific and professional As a corrolary, doping is becoming extremely difficult to detect: because many prohibited drugs are rapidly metabolized (short half life); it is often impossible to distinguish between the natural and recombinant hormone products; several prohibited substances are not screened for; therapeutic use authorization (TUA)--a recent recommendation from the World antidoping agency (WADA)--and advances in gene therapy are giving cheaters new possibilities. It is necessary to promote a new approach to doping detection by determining potential specific links between changes in human biological profiles (proteom, transcriptom, metabonom), and the use of a given drug. Developments in nanotechnology, and notably" labs on a chip" should prove useful in this respect.

  13. Electron transport in doped fullerene molecular junctions

    Science.gov (United States)

    Kaur, Milanpreet; Sawhney, Ravinder Singh; Engles, Derick

    The effect of doping on the electron transport of molecular junctions is analyzed in this paper. The doped fullerene molecules are stringed to two semi-infinite gold electrodes and analyzed at equilibrium and nonequilibrium conditions of these device configurations. The contemplation is done using nonequilibrium Green’s function (NEGF)-density functional theory (DFT) to evaluate its density of states (DOS), transmission coefficient, molecular orbitals, electron density, charge transfer, current, and conductance. We conclude from the elucidated results that Au-C16Li4-Au and Au-C16Ne4-Au devices behave as an ordinary p-n junction diode and a Zener diode, respectively. Moreover, these doped fullerene molecules do not lose their metallic nature when sandwiched between the pair of gold electrodes.

  14. Heteroatom doped graphene in photocatalysis: A review

    Science.gov (United States)

    Putri, Lutfi Kurnianditia; Ong, Wee-Jun; Chang, Wei Sea; Chai, Siang-Piao

    2015-12-01

    Photocatalysis has been a focus of great attention due to its useful environmental applications such as eliminating hazardous pollutants and generating sustainable energy. Coincidentally, graphene, a 2D allotrope of carbon, has also infiltrated many research fields due to its outstanding properties - photocatalysis being no exception. As of recent, there has been growing research focus on heteroatom (O, N, B, P and S) doping of graphene and its emergent application opportunities. In this study, rather than the familiar graphene as the electron transfer medium that is normally integrated in a photocatalyst system, we contrarily explore the implication of heteroatom doped graphene and the underlying mechanism behind their advantageous uses in photocatalysis. This review surveys the literature and highlights recent progress and challenges in the development of chemically doped graphene in the photocatalysis scene. It is desired that this review will promote awareness and encourage further investigations for the development in this budding research area.

  15. Lanthanide-Doped Nanoparticles for Diagnostic Sensing

    Directory of Open Access Journals (Sweden)

    Song Yeul Lee

    2017-11-01

    Full Text Available Lanthanide-doped nanoparticles exhibit unique optical properties, such as a long luminescence lifetime (up to several milliseconds, sharp emission peaks, and upconversion luminescence over the range of wavelengths from near-infrared to visible. Exploiting these optical properties, lanthanide-doped nanoparticles have been widely utilized for cellular and small animal imaging with the absence of background autofluorescence. In addition, these nanoparticles have advantages of high signal-to-noise ratio for highly sensitive and selective diagnostic detection. In this review, we summarize and discuss recent progress in the development of highly sensitive diagnostic methods using lanthanide-doped nanoparticles. Combined with a smartphone, portable luminescence detecting platforms could be widely applied in point-of-care tests.

  16. Electronic properties of doped gapped graphene

    Energy Technology Data Exchange (ETDEWEB)

    Mousavi, Hamze, E-mail: hamze.mousavi@gmail.com [Department of Physics, Razi University, Kermanshah (Iran, Islamic Republic of); Nano Science and Nano Technology Research Center, Razi University, Kermanshah (Iran, Islamic Republic of)

    2013-04-01

    One of the carbon atoms in each Bravais lattice unit cell of pristine graphene plane is substituted by a foreign atom leading to a band gap in the density of states of the system. Then, the gapped graphene is randomly doped by another impurity. The density of states, electronic heat capacity and electrical conductivity of the gapped and doped gapped graphene are investigated within random tight-binding Hamiltonian model and Green's function formalism. The results show that by presence of impurities in the gapped graphene the band gap moves towards lower (higher) values of energy when dopants act as acceptors (donors). The heat capacity decreases (increases) before (after) the Schottky anomaly as well. It is also found that the electrical conductivity of the doped gapped graphene reduces on all ranges of temperature.

  17. Inverted Organic Solar Cells with Low-Temperature Al-Doped-ZnO Electron Transport Layer Processed from Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Qianni Zhang

    2018-01-01

    Full Text Available The aqueous-based Zn-ammine complex solutions represent one of the most promising routes to obtain the ZnO electron transport layer (ETL at a low temperature in inverted organic solar cells (OSCs. However, to dope the ZnO film processed from the Zn-ammine complex solutions is difficult since the introduction of metal ions into the Zn-ammine complex is a nontrivial process as ammonium hydroxide tends to precipitate metal salts due to acid-base neutralization reactions. In this paper, we investigate the inverted OSCs with Al-doped-ZnO ETL made by immersion of metallic Al into the Zn-ammine precursor solution. The effects of ZnO layer with different immersion time of Al on film properties and solar cell performance have been studied. The results show that, with the Al-doped-ZnO ETL, an improvement of the device performance could be obtained compared with the device with the un-doped ZnO ETL. The improved device performance is attributed to the enhancement of charge carrier mobility leading to a decreased charge carrier recombination and improved charge collection efficiency. The fabricated thin film transistors with the same ZnO or AZO films confirm the improved electrical characteristics of the Al doped ZnO film.

  18. Enhanced lithium ion storage in TiO2 nanoparticles, induced by sulphur and carbon co-doping

    Science.gov (United States)

    Ivanov, Svetlozar; Barylyak, Adriana; Besaha, Khrystyna; Dimitrova, Anna; Krischok, Stefan; Bund, Andreas; Bobitski, Jaroslav

    2016-09-01

    Sulphur and carbon codoped anatase nanoparticles are synthesized by one-step approach based on interaction between thiourea and metatitanic acid. Electron microscopy shows micrometer-sized randomly distributed crystal aggregates, consisting of many 25-40 nm TiO2 nanoparticles. The obtained phase composition and chemical states of the elements in the structure are analyzed by means of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). XRD shows that after doping the tetragonal anatase structure is preserved. Further data assessment by Rietveld refinement allows detection of a slight increase of the c lattice parameter and volume related to incorporation of the doping elements. XPS confirms the coexistence of both elemental and oxide carbon forms, which are predominantly located on the TiO2 particle surface. According to XPS analysis sulphur occupies titanium sites and the element is present in S6+ sulfate environment. Analysis based on cyclic voltammetry and galvanostatic intermittent titration (GITT) suggests an accelerated Li+ transport in the doped TiO2 structure. The synthesized S and C co-doped anatase has an excellent electrochemical performance in terms of capacity and very fast lithiation kinetics, superior to the non-doped TiO2. The material displays 83% capacity retention for 500 galvanostatic cycles and nearly 100% current efficiency.

  19. Effect of CSA concentration on the ammonia sensing properties of CSA-doped PA6/PANI composite nanofibers.

    Science.gov (United States)

    Pang, Zengyuan; Fu, Jiapeng; Lv, Pengfei; Huang, Fenglin; Wei, Qufu

    2014-11-13

    Camphor sulfonic acid (CSA)-doped polyamide 6/polyaniline (PA6/PANI) composite nanofibers were fabricated using in situ polymerization of aniline under different CSA concentrations (0.02, 0.04, 0.06, 0.08 and 0.10 M) with electrospun PA6 nanofibers as templates. The structural, morphological and ammonia sensing properties of the prepared composite nanofibers were studied using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), four-point probe techniques, X-ray diffraction (XRD) and a home-made gas sensing test system. All the results indicated that the CSA concentration had a great influence on the sensing properties of CSA-doped PA6/PANI composite nanofibers. The composite nanofibers doped with 0.02 M CSA showed the best ammonia sensing properties, with a significant sensitivity toward ammonia (NH3) at room temperature, superior to that of the composite nanofibers doped with 0.04-0.10 mol/L CSA. It was found that for high concentrations of CSA, the number of PANI-H+ reacted with NH3 would not make up a high proportion of all PANI-H+ within certain limits. As a result, within a certain range even though higher CSA-doped PA6/PANI nanofibers had better conductivity, their ammonia sensing performance would degrade.

  20. Effect of CSA Concentration on the Ammonia Sensing Properties of CSA-Doped PA6/PANI Composite Nanofibers

    Directory of Open Access Journals (Sweden)

    Zengyuan Pang

    2014-11-01

    Full Text Available Camphor sulfonic acid (CSA-doped polyamide 6/polyaniline (PA6/PANI composite nanofibers were fabricated using in situ polymerization of aniline under different CSA concentrations (0.02, 0.04, 0.06, 0.08 and 0.10 M with electrospun PA6 nanofibers as templates. The structural, morphological and ammonia sensing properties of the prepared composite nanofibers were studied using scanning electron microscopy (SEM, Fourier transform infrared spectroscopy (FT-IR, four-point probe techniques, X-ray diffraction (XRD and a home-made gas sensing test system. All the results indicated that the CSA concentration had a great influence on the sensing properties of CSA-doped PA6/PANI composite nanofibers. The composite nanofibers doped with 0.02 M CSA showed the best ammonia sensing properties, with a significant sensitivity toward ammonia (NH3 at room temperature, superior to that of the composite nanofibers doped with 0.04–0.10 mol/L CSA. It was found that for high concentrations of CSA, the number of PANI–H+ reacted with NH3 would not make up a high proportion of all PANI–H+ within certain limits. As a result, within a certain range even though higher CSA-doped PA6/PANI nanofibers had better conductivity, their ammonia sensing performance would degrade.

  1. Doping Attitudes and Covariates of Potential Doping Behaviour in High-Level Team-Sport Athletes; Gender Specific Analysis

    Directory of Open Access Journals (Sweden)

    Damir Sekulic, Enver Tahiraj, Milan Zvan, Natasa Zenic, Ognjen Uljevic, Blaz Lesnik

    2016-12-01

    Full Text Available Team sports are rarely studied with regard to doping behaviour and doping-related factors regardless of their global popularity. This study aimed to investigate doping factors and covariates of potential doping behaviour in high-level team-sport athletes. The subjects were 457 high-performing, national- and international-level athletes (21.9 ± 3.4 years of age; 179 females involved in volleyball (n = 77, soccer (n = 163, basketball (n = 114 and handball (n = 103. Previously validated self-administered questionnaires aimed at evidencing sport factors, doping-related factors, knowledge on sport nutrition and doping, and attitudes to performance enhancement were used. The results indicated a higher doping likelihood in male athletes, with a significant gender difference for basketball and handball. In males, a higher doping likelihood is found for athletes who had achieved better results at junior-age level, those who regularly consume dietary supplements, and who perceive their sport as being contaminated by doping. A higher sport achievement at senior-age level is protective against potential doping behaviour in males. In females, a higher likelihood of doping is evidenced in those athletes involved in binge drinking, while a lower tendency for doping is evidenced in female athletes who possess better knowledge on sport nutrition. Knowledge about doping is very low and thus education about doping is urgently needed. An improvement of knowledge on sport nutrition might be a potentially effective method for reducing the tendency for doping in females. Future studies should consider other approaches and theories, such as theory of planned behaviour and/or social-cognitive theory, in studying the problem of doping behaviour in team-sports.

  2. A general approach for fabrication of nitrogen-doped graphene sheets and its application in supercapacitors.

    Science.gov (United States)

    Wang, Dewei; Min, Yonggang; Yu, Youhai; Peng, Bo

    2014-03-01

    In this paper, a general and efficient strategy has been developed to produce nitrogen-doped graphene sheets (NGs) based on hard and soft acids and bases (HSAB) theory. Under hydrothermal conditions, any salt with amphiprotic character have a strong tendency to hydrolysis, it is possible to provide reducing agent and nitrogen source simultaneously. It is worth noting that, NGs can be prepared under hydrothermal conditions by using some common ammonium salts with hard acid-soft base pairs as nitrogen-doping agents. The morphology, structure and composition of the as-prepared NGs were studied in detail. The results demonstrated that large amount of nitrogen was incorporated into the nanocarbon frameworks at the same time as the graphene oxide (GO) sheets were reduced. The electrochemical behavior of the synthesized NGs as supercapacitor electrodes was evaluated in a symmetric two-electrode cell configuration with 1M H2SO4 as the electrolytes. It was found that the nitrogen groups making the as-prepared NGs exhibited remarkably enhanced electrochemical performance when used as electrode materials in supercapacitors. The supercapacitor based on the NGs exhibited a high specific capacitance of 242 F g(-1) at a current density of 1 A g(-1), and remains a relatively high capacitance even at a high current density. This work will put forward to understand and optimize heteroatom-doped graphene in energy storage systems. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Synthesis and drug detection performance of nitrogen-doped carbon dots

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Jingjing [Functional and Environment Materials Research Institute, College of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China); Nano Structure and Low Dimensional Physics Laboratory, Peking University, Beijing 100871 (China); Gao, Hui, E-mail: hope@lzu.edu.cn [Functional and Environment Materials Research Institute, College of Physical Science and Technology, Lanzhou University, Lanzhou 730000 (China)

    2014-05-01

    Recently, nitrogen-doped carbon dots (NCDs) have attracted considerable interest since nitrogen (N) doping could effectively tailor the electronic properties and the chemical reactivity of carbon dots (CDs) for advanced potential applications. Herein, a one-step pyrolysis method was presented for synthesizing the NCDs with excellent water solubility, good stability and a high quantum yield of ca. 28%. The detection performance of NCDs for the antibacterial drugs was further explored, and it was proved to effectively enhance the fluorescence due to the strong interaction between the NCDs and antibacterial drugs. - Highlights: • A facile yet economic bottom-up pyrolysis method for synthesizing nitrogen (N)-doped carbon dots (NCDs) using glutamic acid as the precursor. • Glutamic acid was the only starting material and used as a source of carbon and nitrogen; the formation and functionalization of NCDs were accomplished simultaneously. • The NCDs possess bright blue emission (with a high quantum yield of ca. 28%) and excellent excitation dependent on PL properties. • NCDs were used for the determination of antibacterial drugs based on the fluorescence enhancement.

  4. Design and Synthesis of Cross-Linked Copolymer Membranes Based on Poly(benzoxazine and Polybenzimidazole and Their Application to an Electrolyte Membrane for a High-Temperature PEM Fuel Cell

    Directory of Open Access Journals (Sweden)

    Hyuk Chang

    2013-01-01

    Full Text Available Elevated-temperature (100~200 °C polymer electrolyte membrane (PEM fuel cells have many features, such as their high efficiency and simple system design, that make them ideal for residential micro-combined heat and power systems and as a power source for fuel cell electric vehicles. A proton-conducting solid-electrolyte membrane having high conductivity and durability at elevated temperatures is essential, and phosphoric-acid-containing polymeric material synthesized from cross-linked polybenzoxazine has demonstrated feasible characteristics. This paper reviews the design rules, synthesis schemes, and characteristics of this unique polymeric material. Additionally, a membrane electrode assembly (MEA utilizing this polymer membrane is evaluated in terms of its power density and lifecycle by an in situ accelerated lifetime test. This paper also covers an in-depth discussion ranging from the polymer material design to the cell performance in consideration of commercialization requirements.

  5. Effects of Fe doping on the structures and properties of hexagonal birnessites - Comparison with Co and Ni doping

    NARCIS (Netherlands)

    Yin, H.; Liu, F.; Feng, X.H.; Hu, T.D.; Zheng, L.R.; Qiu, G.H.; Koopal, L.K.; Tan, W.F.

    2013-01-01

    Fe-doped hexagonal birnessite was synthesized by adding Fe3+ to the initial reactants, and the effects of Fe doping on the structures and properties of birnessite were investigated and compared with the effects of Co and Ni doping. The underlying mechanisms controlling the incorporation of

  6. Hierarchically structured, nitrogen-doped carbon membranes

    KAUST Repository

    Wang, Hong

    2017-08-03

    The present invention is a structure, method of making and method of use for a novel macroscopic hierarchically structured, nitrogen-doped, nano-porous carbon membrane (HNDCMs) with asymmetric and hierarchical pore architecture that can be produced on a large-scale approach. The unique HNDCM holds great promise as components in separation and advanced carbon devices because they could offer unconventional fluidic transport phenomena on the nanoscale. Overall, the invention set forth herein covers a hierarchically structured, nitrogen-doped carbon membranes and methods of making and using such a membranes.

  7. Optical sensing of HCl with phenol red doped sol-gels

    Energy Technology Data Exchange (ETDEWEB)

    Wang Enju [Department of Chemistry, St. John' s University, 8000 Utopia Parkway, Jamaica, NY 11439 (United States)]. E-mail: wange@stjohns.edu; Chow, Kwok-Fan [Department of Chemistry, St. John' s University, 8000 Utopia Parkway, Jamaica, NY 11439 (United States); Wang Wenqun [Department of Chemistry, St. John' s University, 8000 Utopia Parkway, Jamaica, NY 11439 (United States); Wong, Crystal [Department of Chemistry, St. John' s University, 8000 Utopia Parkway, Jamaica, NY 11439 (United States); Yee, Cynthia [Department of Chemistry, St. John' s University, 8000 Utopia Parkway, Jamaica, NY 11439 (United States); Persad, Alvin [Department of Chemistry, St. John' s University, 8000 Utopia Parkway, Jamaica, NY 11439 (United States); Mann, Jonathan [Department of Chemistry, Princeton University, Princeton, NJ 08540 (United States); Bocarsly, Andrew [Department of Chemistry, Princeton University, Princeton, NJ 08540 (United States)

    2005-04-08

    A dye doped sol-gel for the sensing of hydrochloric acid in solution and/or gaseous phase is described. The sol-gel is obtained by acidic hydrolysis of tetraethoxysilane (TEOS) and phenyltriethoxysilane (Ph-TriEOS) in the presence of phenol red (PR) and further spin-coating onto glass slides. The sensitive response is based on an increase of the absorption band at 510 nm of phenol red entrapped in the sol-gel casting when exposed to HCl solution or gas, due to protonation of the dye. The detection limit of the sol-gel response to moisturized gaseous HCl is below 12 ppm, and its response to HCl in solution falls in the range of 0.01-6 M. The sol-gel coating has a response time of less than 40 s in steady-state, and life-time of more than a year. Weak acids such as acetic acid, benzoic acid, salicylate acid, citrate acid, and carbonic acid do not interfere the response. The responses in acid solutions are completely reversible. In the gaseous phase, response of HCl appears to be moisture sensitive.

  8. Stabilization of aluminum doped zinc oxide nanoparticle suspensions and their application in organic solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Wolf, N., E-mail: nadine.wolf@zae-bayern.de [Bavarian Center for Applied Energy Research (ZAE Bayern), Division: Energy Efficiency, Am Galgenberg 87, 97074 Wuerzburg (Germany); Stubhan, T. [Institute of Materials for Electronics and Energy Technology (I-MEET), Friedrich-Alexander-University of Erlangen-Nuremberg, Martensstraße 7, 91058 Erlangen (Germany); Manara, J.; Dyakonov, V. [Bavarian Center for Applied Energy Research (ZAE Bayern), Division: Energy Efficiency, Am Galgenberg 87, 97074 Wuerzburg (Germany); Brabec, C.J. [Institute of Materials for Electronics and Energy Technology (I-MEET), Friedrich-Alexander-University of Erlangen-Nuremberg, Martensstraße 7, 91058 Erlangen (Germany); Bavarian Center for Applied Energy Research (ZAE Bayern), Division: Renewable Energies, Haberstraße 2a, 91058 Erlangen (Germany)

    2014-08-01

    Aluminum doped zinc oxide (AZO) nanoparticles were redispersed in isopropyl alcohol and stabilized with different stabilizers and mixtures of stabilizers that allow for electronically functional particles. The size of the redispersed nanoparticles was small enough to use these suspensions to build interfacial layers in inverted polymer-fullerene solar cells. The performance of these devices was found to depend on the stabilizer used in the nanoparticle suspension. The best performance was obtained with an AZO interfacial layer built with a 3,6,9-trioxadecanoic acid and polyvinylpyrrolidone stabilized nanoparticle suspension. - Highlights: • Preparation of stable aluminum doped zinc oxide nanoparticle suspensions • Different stabilizers were used to stabilize these nanoparticle suspensions. • The material was used as interfacial layers in inverted polymer solar cells. • The performance of these devices depends on the stabilizer used in the suspension.

  9. Microemulsion synthesis and characterization of aluminum doped ZnO nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Lim, S.K.; Hwang, S.H.; Kim, S. [Division of Nano and Bio Technology, Daegu Gyeongbuk Institute of Science and Technology DGIST, Daegu 700-742 (Korea)

    2010-07-15

    Aluminium doped ZnO (AZO) nanorods were synthesized by microemulsion method with different types of surfactants. Scanning electron microscopy observations show that the ZnO nanorods have diameters around about 80 nm and lengths up to several micrometers. The room temperature photoluminescence (PL) spectrum of AZO nanorods exhibited a sharp and strong ultraviolet bandgap at 383 nm and a relatively weaker emission associated with the defect level. AZO nanorods synthesized with sodium benzene sulfonate (SBS) surfactant showed lower resistivity than aluminum doped ZnO nanorods synthesized with dodecyl benzene sulfonic acid sodium salt (DBS) surfactant. Resistivity of AZO nanorods synthesized with SBS surfactant showed 2.8 x 10{sup 3} and ohm;cm. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Current anti-doping policy: a critical appraisal

    Directory of Open Access Journals (Sweden)

    Mauron Alexandre

    2007-03-01

    Full Text Available Abstract Background Current anti-doping in competitive sports is advocated for reasons of fair-play and concern for the athlete's health. With the inception of the World Anti Doping Agency (WADA, anti-doping effort has been considerably intensified. Resources invested in anti-doping are rising steeply and increasingly involve public funding. Most of the effort concerns elite athletes with much less impact on amateur sports and the general public. Discussion We review this recent development of increasingly severe anti-doping control measures and find them based on questionable ethical grounds. The ethical foundation of the war on doping consists of largely unsubstantiated assumptions about fairness in sports and the concept of a "level playing field". Moreover, it relies on dubious claims about the protection of an athlete's health and the value of the essentialist view that sports achievements reflect natural capacities. In addition, costly antidoping efforts in elite competitive sports concern only a small fraction of the population. From a public health perspective this is problematic since the high prevalence of uncontrolled, medically unsupervised doping practiced in amateur sports and doping-like behaviour in the general population (substance use for performance enhancement outside sport exposes greater numbers of people to potential harm. In addition, anti-doping has pushed doping and doping-like behaviour underground, thus fostering dangerous practices such as sharing needles for injection. Finally, we argue that the involvement of the medical profession in doping and anti-doping challenges the principles of non-maleficience and of privacy protection. As such, current anti-doping measures potentially introduce problems of greater impact than are solved, and place physicians working with athletes or in anti-doping settings in an ethically difficult position. In response, we argue on behalf of enhancement practices in sports within a

  11. Optical properties of highly n-doped germanium obtained by in situ doping and laser annealing

    Science.gov (United States)

    Frigerio, J.; Ballabio, A.; Gallacher, K.; Gilberti, V.; Baldassarre, L.; Millar, R.; Milazzo, R.; Maiolo, L.; Minotti, A.; Bottegoni, F.; Biagioni, P.; Paul, D.; Ortolani, M.; Pecora, A.; Napolitani, E.; Isella, G.

    2017-11-01

    High n-type doping in germanium is essential for many electronic and optoelectronic applications especially for high performance Ohmic contacts, lasing and mid-infrared plasmonics. We report on the combination of in situ doping and excimer laser annealing to improve the activation of phosphorous in germanium. An activated n-doping concentration of 8.8  ×  1019 cm‑3 has been achieved starting from an incorporated phosphorous concentration of 1.1  ×  1020 cm‑3. Infrared reflectivity data fitted with a multi-layer Drude model indicate good uniformity over a 350 nm thick layer. Photoluminescence demonstrates clear bandgap narrowing and an increased ratio of direct to indirect bandgap emission confirming the high doping densities achieved.

  12. Hydrogen Solubility in Pr-doped and Un-doped YSZ for One Chamber Fuel Cell

    DEFF Research Database (Denmark)

    Bay, Lasse; Horita, T.; Sakai, N.

    1998-01-01

    Yttria-stabilised zirconia electrolytes (YSZ and Pr-doped YSZ) and yttria-doped strontium cerate (SYC) were tested in a one chamber fuel cell fed with a mixture of methane and air at 1223 K. The obtained performances were 4 mW cm(-2), 3 mW cm(-2), 2.5 mW cm(-2), and 0.15 mW cm(-2) for SYC, 1.8 mol...... SIMS analysis. Doping of Pr in the YSZ resulted in a higher intensity of the D ion, which indicated that hydrogen solubility was raised by the doping. The solubility of hydrogen in the electrolyte may affect the performance of one chamber fuel cells. (C) 1998 Elsevier Science B.V. All rights reserved....

  13. One step synthesis of P-doped g-C3N4 with the enhanced visible light photocatalytic activity

    Science.gov (United States)

    Liu, Sen; Zhu, Honglei; Yao, Wenqing; Chen, Kai; Chen, Daimei

    2018-02-01

    In our work, P doped Graphitic nitride (g-C3N4) was prepared by the simple copolymerization of melamine and melamine phosphate. The melamine phosphate ester polymer is a complex of an s-triazine and phosphoric acid polymer, thus it will be favourable for P atom to incorporate into the Csbnd N network of g-C3N4. The doped P atoms may produce the delocalized lone electron and form the Lewis acid sites. The obtained P-doped g-C3N4 showed the higher photocatalytic activity in photodegradation of MB and 2,4-Dichlorophenol than g-C3N4. The optimum photocatatlytic activity of P-C3N4 with the weight ration of melamine phosphate and melamine at 0.06 is 2 times as higher as the pure g-C3N4 in MB photodegradation, and 1.5 times higher in 2,4-Dichlorophenol photodegradation. The enhancement of photodegradation efficiency is due to the delocalization effect of lone electron, promoting the separation of photogenerated charges, and the larger band gap of P doped g-C3N4.

  14. Study of Cu-doping effects on magnetic properties of Fe-doped ZnO ...

    Indian Academy of Sciences (India)

    Administrator

    Study of Cu-doping effects on magnetic properties of Fe-doped ZnO by first principle calculations. A EL AMIRI*, H LASSRI†, M ABID and E K HLIL††. Laboratoire de Physique Fondamentale et Appliquée (LPFA), Faculté des Sciences Ain Chock,. Université Hassan II, B.P. 5366 Mâarif, Casablanca, Morroco. †Laboratoire de ...

  15. Effects of Different Doping Ratio of Cu Doped CdS on QDSCs Performance

    Directory of Open Access Journals (Sweden)

    Xiaojun Zhu

    2015-01-01

    Full Text Available We use the successive ionic layer adsorption and reaction (SILAR method for the preparation of quantum dot sensitized solar cells, to improve the performance of solar cells by doping quantum dots. We tested the UV-Vis absorption spectrum of undoped CdS QDSCs and Cu doped CdS QDSCs with different doping ratios. The doping ratios of copper were 1 : 100, 1 : 500, and 1 : 1000, respectively. The experimental results show that, under the same SILAR cycle number, Cu doped CdS quantum dot sensitized solar cells have higher open circuit voltage, short circuit current density photoelectric conversion efficiency than undoped CdS quantum dots sensitized solar cells. Refinement of Cu doping ratio are 1 : 10, 1 : 100, 1 : 200, 1 : 500, and 1 : 1000. When the proportion of Cu and CdS is 1 : 10, all the parameters of the QDSCs reach the minimum value, and, with the decrease of the proportion, the short circuit current density, open circuit voltage, and the photoelectric conversion efficiency are all increased. When proportion is 1 : 500, all parameters reach the maximum values. While with further reduction of the doping ratio of Cu, the parameters of QDSCs have a decline tendency. The results showed that, in a certain range, the lower the doping ratio of Cu, the better the performance of quantum dot sensitized solar cell.

  16. Catalytic hydrogenation of CO2 over Pt- and Ni-doped graphene: A comparative DFT study.

    Science.gov (United States)

    Esrafili, Mehdi D; Sharifi, Fahimeh; Dinparast, Leila

    2017-10-01

    Today, the global greenhouse effect of carbon dioxide (CO2) is a serious environmental problem. Therefore, developing efficient methods for CO2 capturing and conversion to valuable chemicals is a great challenge. The aim of the present study is to investigate the catalytic activity of Pt- or Ni-doped graphene for the hydrogenation of CO2 by a hydrogen molecule. To gain a deeper insight into the catalytic mechanism of this reaction, the reliable density functional theory calculations are performed. The adsorption energies, geometric parameters, reaction barriers, and thermodynamic properties are calculated using the M06-2X density functional. Two reaction mechanisms are proposed for the hydrogenation of CO2. In the bimolecular mechanism, the reaction proceeds in two steps, initiating by the co-adsorption of CO2 and H2 molecules over the surface, followed by the formation of a OCOH intermediate by the transfer of H atom of H2 toward O atom of CO2. In the next step, formic acid is produced as a favorable product with the formation of CH bond. In our proposed termolecular mechanism, however, H2 molecule is directly activated by the two pre-adsorbed CO2 molecules. The predicted activation energy for the formation of the OCOH intermediate in the bimolecular mechanism is 20.8 and 47.9kcalmol-1 over Pt- and Ni-doped graphene, respectively. On the contrary, the formation of the first formic acid in the termolecular mechanism is found as the rate-determining step over these surfaces, with an activation energy of 28.8 and 45.5kcal/mol. Our findings demonstrate that compared to the Ni-doped graphene, the Pt-doped surface has a relatively higher catalytic activity towards the CO2 reduction. These theoretical results could be useful in practical applications for removal and transformation of CO2 to value-added chemical products. Copyright © 2017 Elsevier Inc. All rights reserved.

  17. Electrical characterization of proton conducting polymer electrolyte based on bio polymer with acid dopant

    Energy Technology Data Exchange (ETDEWEB)

    Kalaiselvimary, J.; Pradeepa, P.; Sowmya, G.; Edwinraj, S.; Prabhu, M. Ramesh, E-mail: email-mkram83@gmail.com [Department of Physics, Alagappa University, Karaikudi – 630 004, India. (India)

    2016-05-06

    This study describes the biodegradable acid doped films composed of chitosan and Perchloric acid with different ratios (2.5 wt %, 5 wt %, 7.5 wt %, 10 wt %) was prepared by the solution casting technique. The temperature dependence of the proton conductivity of complex electrolytes obeys the Arrhenius relationship. Proton conductivity of the prepared polymer electrolyte of the bio polymer with acid doped was measured to be approximately 5.90 × 10{sup −4} Scm{sup −1}. The dielectric data were analyzed using Complex impedance Z*, Dielectric loss ε’, Tangent loss for prepared polymer electrolyte membrane with the highest conductivity samples at various temperature.

  18. Morphology and Doping Engineering of Sn-Doped Hematite Nanowire Photoanodes.

    Science.gov (United States)

    Li, Mingyang; Yang, Yi; Ling, Yichuan; Qiu, Weitao; Wang, Fuxin; Liu, Tianyu; Song, Yu; Liu, Xiaoxia; Fang, Pingping; Tong, Yexiang; Li, Yat

    2017-04-12

    High-temperature activation has been commonly used to boost the photoelectrochemical (PEC) performance of hematite nanowires for water oxidation, by inducing Sn diffusion from fluorine-doped tin oxide (FTO) substrate into hematite. Yet, hematite nanowires thermally annealed at high temperature suffer from two major drawbacks that negatively affect their performance. First, the structural deformation reduces light absorption capability of nanowire. Second, this "passive" doping method leads to nonuniform distribution of Sn dopant in nanowire and limits the Sn doping concentration. Both factors impair the electrochemical properties of hematite nanowire. Here we demonstrate a silica encapsulation method that is able to simultaneously retain the hematite nanowire morphology even after high-temperature calcination at 800 °C and improve the concentration and uniformity of dopant distribution along the nanowire growth axis. The capability of retaining nanowire morphology allows tuning the nanowire length for optimal light absorption. Uniform distribution of Sn doping enhances the donor density and charge transport of hematite nanowire. The morphology and doping engineered hematite nanowire photoanode decorated with a cobalt oxide-based oxygen evolution reaction (OER) catalyst achieves an outstanding photocurrent density of 2.2 mA cm-2 at 0.23 V vs Ag/AgCl. This work provides important insights on how the morphology and doping uniformity of hematite photoanodes affect their PEC performance.

  19. Polypyrrole Doped with Alkyl Benzene Sulphonates

    DEFF Research Database (Denmark)

    Bay, Lasse; Mogensen, Naja; Skaarup, Steen

    2002-01-01

    The properties of polypyrrole (PPy) are to a large extent determined by the condition of synthesis and especially by the counterion incorporated as dopant during synthesis. In this work, PPy doped with different alkyl benzenesulfonates are compared. The polymer films are prepared by constant curr...

  20. Doping-induced luminescence in polyacetylene

    Science.gov (United States)

    Kürti, J.; Kuzmany, H.

    1988-09-01

    In situ measurements of the emission of secondary radiation from trans-polyacetylene during electrochemical p and n doping are reported. The luminescencelike emission was observed to be reversible with the doping and undoping process, and it was independent with respect to three different electrolyte systems: Li+ClO-4 in sulfolane, Li+ClO-4 in propylenecarbonate, and Li+BF-4 in propylenecarbonate, which proves its origin from the polymer backbone. No reversible luminescence occurs during n doping. The intensity of the luminescence spectrum has a maximum for the laser excitation in the yellow-green spectral region. The maximum position of the luminescence spectrum shifts by about 3000 cm-1 for a shift of the excitation energy of 7000 cm-1. The observed luminescence phenomena are explained by the polaron-doping mechanism in the disordered part of the sample and photoselective resonance process. A quantitative description is presented by calculating the energy for polaron levels by the Hückel method including geometry relaxation.

  1. Characterization of Fe -doped silver phosphate glasses

    Indian Academy of Sciences (India)

    tures of the glass and at lower concentration of dopant, a nanostructure is obtained. Electrical conductivity mea- surements from 303 to 373 K in a frequency range from 100 Hz to 5 MHz have indicated that all glasses are ionic conductors with Ag+ ions as the charge carrier. Fe2O3 doping in silver phosphate glass increased ...

  2. Self-activating and doped tantalate phosphors.

    Energy Technology Data Exchange (ETDEWEB)

    Nyman, May Devan; Rohwer, Lauren Elizabeth Shea

    2011-01-01

    An ideal red phosphor for blue LEDs is one of the biggest challenges for the solid-state lighting industry. The appropriate phosphor material should have good adsorption and emission properties, good thermal and chemical stability, minimal thermal quenching, high quantum yield, and is preferably inexpensive and easy to fabricate. Tantalates possess many of these criteria, and lithium lanthanum tantalate materials warrant thorough investigation. In this study, we investigated red luminescence of two lithium lanthanum tantalates via three mechanisms: (1) Eu-doping, (2) Mn-doping and (3) self-activation of the tantalum polyhedra. Of these three mechanisms, Mn-doping proved to be the most promising. These materials exhibit two very broad adsorption peaks; one in the UV and one in the blue region of the spectrum; both can be exploited in LED applications. Furthermore, Mn-doping can be accomplished in two ways; ion-exchange and direct solid-state synthesis. One of the two lithium lanthanum tantalate phases investigated proved to be a superior host for Mn-luminescence, suggesting the crystal chemistry of the host lattice is important.

  3. Gene doping: the hype and the reality.

    Science.gov (United States)

    Wells, D J

    2008-06-01

    Some spectacular results from genetic manipulation of laboratory rodents and increasing developments in human gene therapy raise the spectre of genetic modification or 'gene doping' in sports. Candidate targets include the induction of muscle hypertrophy through overexpression of specific splice variants of insulin-like growth factor-1 or blockade of the action of myostatin, increasing oxygen delivery by raising the hematocrit through the use of erythropoietin, induction of angiogenesis with vascular endothelial growth factors or related molecules and changes in muscle phenotype through expression of peroxisome-proliferator-activated receptor- delta and associated molecules. Some of these potential genetic enhancements, particularly where the genetic modification and its action are confined to the muscles, may be undetectable using current tests. This had lead to exaggerated predictions that gene doping in athletics will be common within the next few years. However, a review of the methods of gene transfer and the current 'state of the art' in development of genetic treatments for human disease show that the prospects for gene doping remain essentially theoretical at present. Despite this conclusion, it will be important to continue to monitor improvements in the technology and to develop methods of detection, particularly those based on identifying patterns of changes in response to doping as opposed to the detection of specific agents.

  4. Recombination mechanisms and doping density in silicon

    Science.gov (United States)

    Passari, Luigi; Susi, Enrichetta

    1983-07-01

    Carrier recombination in silicon is analyzed as a function of doping density. Two mechanisms are identified: one for the low concentration range and one, of the Auger type, for the high concentration range. Disagreements with the theoretical predictions for the Auger process are discussed and empirical laws connecting lifetime to dopant concentration are determined.

  5. Blood doping : infusions, erythropoietin and artificial blood.

    Science.gov (United States)

    Eichner, E Randy

    2007-01-01

    As science marches on, athletes and coaches march close behind. Researchers have long been interested in how red cell mass and blood volume affect exercise capacity. Interest in blood doping soared after the 1968 Mexico City Olympics. Studies in the 1970s and 1980s suggested that transfusing red cells could speed endurance performance. Diverse athletes of the time were accused of blood doping. In the late 1980s, recombinant human erythropoietin (EPO) began to supplant transfusion for doping. EPO use is a suspect in nearly 20 deaths in 4 years in European cyclists. In the 1998 Tour de France, a team was ejected for using EPO and six other teams quit the race. The beat goes on; in recent years, diverse endurance and sprint athletes have been caught or accused of using EPO. Tests to detect EPO are improving but are not yet foolproof. As EPO tests improve, blood transfusion is back in vogue and some athletes may have infused artificial blood. Tests for detecting artificial blood also exist, but it seems it will take widespread, year-round, unannounced, out-of-competition testing and stern penalties to deter blood doping.

  6. Preparation of Polyaniline-Doped Fullerene Whiskers

    Directory of Open Access Journals (Sweden)

    Bingzhe Wang

    2013-01-01

    Full Text Available Fullerene C60 whiskers (FWs doped with polyaniline emeraldine base (PANI-EB were synthesized by mixing PANI-EB/N-methyl pyrrolidone (NMP colloid and FWs suspension based on the nature of the electron acceptor of C60 and electron donor of PANI-EB. Scanning electron microscopy (SEM, Fourier transform infrared (FT-IR, and ultraviolet-visible (UV-Vis spectra characterized the morphology and molecular structure of the FWs doped with PANI-EB. SEM observation showed that the smooth surface of FWs was changed to worm-like surface morphology after being doped with PANI-EB. The UV-Vis spectra suggested that charge-transfer (CT complex of C60 and PANI-EB was formed as PANI-EBδ+-C60δ-. PANI-EB-doped FWs might be useful as a new type of antibacterial and self-cleaning agent as well as multifunctional material to improve the human health and living environment.

  7. Electronic properties of magnetically doped nanotubes

    Indian Academy of Sciences (India)

    Effect of doping of carbon nanotubes by magnetic transition metal atoms has been considered in this paper. In the case of semiconducting tubes, it was found that the system has zero magnetization, whereas in metallic tubes the valence electrons of the tube screen the magnetization of the dopants: the coupling to the tube ...

  8. Electron Doping a Kagome Spin Liquid

    Directory of Open Access Journals (Sweden)

    Z. A. Kelly

    2016-10-01

    Full Text Available Herbertsmithite, ZnCu_{3}(OH_{6}Cl_{2}, is a two-dimensional kagome lattice realization of a spin liquid, with evidence for fractionalized excitations and a gapped ground state. Such a quantum spin liquid has been proposed to underlie high-temperature superconductivity and is predicted to produce a wealth of new states, including a Dirac metal at 1/3 electron doping. Here, we report the topochemical synthesis of electron-doped ZnLi_{x}Cu_{3}(OH_{6}Cl_{2} from x=0 to x=1.8 (3/5 per Cu^{2+}. Contrary to expectations, no metallicity or superconductivity is induced. Instead, we find a systematic suppression of magnetic behavior across the phase diagram. Our results demonstrate that significant theoretical work is needed to understand and predict the role of doping in magnetically frustrated narrow band insulators, particularly the interplay between local structural disorder and tendency toward electron localization, and pave the way for future studies of doped spin liquids.

  9. Biological passport in the fight against doping

    Directory of Open Access Journals (Sweden)

    Mitja Ferlež

    2012-10-01

    for new ways of proving abuse of prohibited substances and methods. One of these is the strategy of long-term monitoring of biomarkers for identifying and sanctioning blood doping in athletes. This strategy is based on the assumption that doping will change values of biomarkers of the athlete that are otherwise kept in homeostasis. If we use a validated mathematical model, it is possible to determine whether the change in the values of biomarkers is due to doping or due to natural variations. Such a model is a biological passport, which enables the identification of the abnormal blood changes in biological indicators of the athlete. Since 2010 it has been possible to introduce sanctions against the athlete for breach of anti-doping rules based solely on an abnormal change of biomarkers. The introduction of the biological passport is a milestone in demonstrating drug abuse in sports, because it substantiates the abnormal deviations of biomarkers from the expected, although the cause of it remains unknown.

  10. Structure and functionality of bromine doped graphite.

    Science.gov (United States)

    Hamdan, Rashid; Kemper, A F; Cao, Chao; Cheng, H P

    2013-04-28

    First-principles calculations are used to study the enhanced in-plane conductivity observed experimentally in Br-doped graphite, and to study the effect of external stress on the structure and functionality of such systems. The model used in the numerical calculations is that of stage two doped graphite. The band structure near the Fermi surface of the doped systems with different bromine concentrations is compared to that of pure graphite, and the charge transfer between carbon and bromine atoms is analyzed to understand the conductivity change along different high symmetry directions. Our calculations show that, for large interlayer separation between doped graphite layers, bromine is stable in the molecular form (Br2). However, with increased compression (decreased layer-layer separation) Br2 molecules tend to dissociate. While in both forms, bromine is an electron acceptor. The charge exchange between the graphite layers and Br atoms is higher than that with Br2 molecules. Electron transfer to the Br atoms increases the number of hole carriers in the graphite sheets, resulting in an increase of conductivity.

  11. Characterisation, phase stability and surface chemical properties of photocatalytic active Zr and Y co-doped anatase TiO2 nanoparticles

    Science.gov (United States)

    Mattsson, Andreas; Lejon, Christian; Bakardjieva, Snejana; Štengl, Vaclav; Österlund, Lars

    2013-03-01

    We report on the characterization, phase stability, surface chemical and photocatalytic properties of Zr and Y co-doped anatase TiO2 nanoparticles prepared by homogenous hydrolysis methods using urea as precipitating agent. The materials were analyzed by scanning electron microscopy, X-ray diffraction, Raman spectroscopy, BET isotherm and BJH pore size distribution measurements. It is shown that Y and Zr ions replace Ti ions in the anatase TiO2 structures up to a critical total dopant concentration of approximately 13 wt%. The co-doped particles show increased phase stability compared to pure anatase TiO2 nanoparticles. The anatase to rutile phase transformation is shown to be preceded by cation segregation and dissolution with concomitant precipitation of Y2Ti2-xZrxO7 and ZrTiO4. Co-doping modifies the optical absorption edge with a resulting attenuation of the Urbach tail. The band gap is slightly blue-shifted at high doping concentrations, and red shifted at lower doping concentrations. Formic acid adsorption was used as a probe molecule to investigate surface chemical properties and adsorbate structures. It was found that the relative abundance of monodentate formate compared to bidentate coordinated formate decreases with increasing doping concentration. This is attributed to an increased surface acidity with increasing dopant concentration. Photodegradation of formic acid occurred on all samples. With mode-resolved in situ FTIR spectroscopy it is shown that the rate of photodegradation of monodentate formate species are higher than for bidentate formate species. Thus our results show that the trend of decreasing photo-degradation rate with increasing dopant concentration can be explained by the adsorbate structure, which is controlled by the acidity of the surface.

  12. Structural and optical properties of Tb and Na–Tb co-doped Ca3V2O8 phosphors prepared by sol–gel process

    Science.gov (United States)

    Parab, Shambhu S.; Salker, A. V.

    2018-01-01

    A malic acid assisted sol–gel route was successfully employed to prepare two distinct series of green emitting Ca3V2O8 phosphors. In the first series, Tb was solely doped whereas in the second series Na and Tb were doped simultaneously in the Ca3V2O8 crystal lattice. X-ray diffraction studies proved the utility of adopted preparative method by confirming the monophasic formation of all compounds from both the series. Spectral analysis like Raman spectroscopy, UV-DRS were undertaken to analyse the local structure, crystallinity and absorptive characteristics. XPS validated the presence of desired oxidation states of all the elements present. Finally, photoluminescence studies were done to elucidate the scope of prepared compounds as green emitting phosphors and also to understand the effect of both doping schemes on the luminescence. Intense green emission was observed in both the cases. Tb concentration of 0.08 was found to be optimum in case of Tb singly doped compounds whereas Tb = 0.12 showed highest intensity among the Na–Tb co-doped samples. Moreover, a red shift in the excitation wavelength was observed after Na doping signifying a change in the local electronic environment which in turn has affected the luminescence pattern. Local crystallinity and vacancy concentrations were found to have a major say on the emission intensities.

  13. Synthesis, thermoluminescence and dosimetric properties of La-doped zinc borates

    Energy Technology Data Exchange (ETDEWEB)

    Kucuk, Nil, E-mail: nilkoc@uludag.edu.tr [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey); Kucuk, Ilker; Cakir, Merve [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey); Kaya Keles, Sule [Institute of Nuclear Science, Ankara University, Tandogan Campus, 06550 Ankara (Turkey)

    2013-07-15

    Dependence on the dose of beta radiation of undoped and La-doped ZnB{sub 2}O{sub 4} powder samples at 1%, 2%, 3%, 4%, 5% and 10% (by weight) was investigated by thermoluminescence technique. Powder samples were synthesized by the nitric acid method using the starting oxides [zinc oxide (ZnO), boric acid (H{sub 3}BO{sub 3}) and doped element oxide (La{sub 2}O{sub 3})]. The samples were characterized by X-ray diffraction (XRD). The thermoluminescence (TL) properties of the powder samples were measured with Risø TL/OSL DA-20 reader. TL glow curves were obtained with heating at a constant heating rate of 5 °C/s up to 450 °C. The dose response curves of the powder samples exposed to {sup 90}Sr beta radiation (40 mCi) were obtained in the dose range from 143 mGy to 60 Gy. Dose responses and minimum detectable dose (MDD) values for increasing radiation doses of the powder samples were determined. The dose responses of all the samples have shown a quite linear response to beta radiation. MDD value of 10% La-doped ZnB{sub 2}O{sub 4} powder sample which shows a high temperature peak at 207 °C was determined as 4 mGy. MDD values for 1%, 2%, 3%, 4% and 5% La-doped ZnB{sub 2}O{sub 4} powder samples were also determined as 10 mGy, 50 mGy, 10 mGy, 10 mGy and 30 mGy, respectively. Luminescence intensities of the powder samples were shown to be likely to be used for low radiation doses. Highlights: ► Powder samples of undoped and La-doped zinc borate were prepared by the nitric acid method. ► TL properties and dependence on the dose of beta radiation of the samples have been investigated. ► The dose responses of the powder samples showed good linearity. ► The results showed that ZnB{sub 2}O{sub 4}:La sample can be a promising TLD material for dosimetric applications.

  14. The world anti-doping code : a South African perspective : research ...

    African Journals Online (AJOL)

    During February 2003 the World Anti-Doping Agency adopted the World-Anti Doping Code in Copenhagen in an effort to create and independent anti-doping body and to co-ordinate the harmonisation of doping regulations. The Code encompasses the principles around which the anti-doping effort in sport will revolve in ...

  15. Nanoporous Sulfur-Doped Copper Oxide (Cu2OxS1-x) for Overall Water Splitting.

    Science.gov (United States)

    Zhang, Xiaolin; Cui, Xiaoqiang; Sun, Yuanhui; Qi, Kun; Jin, Zhao; Wei, Shuting; Li, Weiwei; Zhang, Lijun; Zheng, Weitao

    2018-01-10

    Developing active and bifunctional noble metal-free electrocatalysts is crucial for both the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) in the full water splitting process. A ternary nanoporous sulfur-doped copper oxide (Cu 2 O x S 1-x ) was successfully synthesized on Cu foam. The obtained Cu 2 O x S 1-x /Cu shows robust electrocatalytic activity toward HER with a low overpotential of 40 mV at 10 mA cm -2 and a Tafel slope of 68 mV dec -1 and exhibits long-term stability in acid solution. Moreover, Cu 2 O x S 1-x shows excellent electrocatalytic activity for OER, HER, and overall water splitting as a bifunctional catalyst in 1.0 M KOH electrolyte. The sulfur doping strategy implemented here can greatly improve the catalytic performance and stability in both acidic and alkaline water electrolyzers and presents an efficient catalyst for overall water splitting.

  16. Photocatalytic degradation of organic dyes by Er3+: YAlO3/Co- and Fe-doped ZnO coated composites under solar irradiation

    Science.gov (United States)

    Chen, Yang; Lu, Chunxiao; Tang, Liang; Song, Yahui; Wei, Shengnan; Rong, Yang; Zhang, Zhaohong; Wang, Jun

    2016-12-01

    In this work, the Er3+: YAlO3/Co- and Fe-doped ZnO coated composites were prepared by the sol-gel method. Then, they were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDX). Photo-degradation of azo fuchsine (AF) as a model dye under solar light irradiation was studied to evaluate the photocatalytic activity of the Er3+: YAlO3/Co- and Fe-doped ZnO coated composites. It was found that the photocatalytic activity of Co- and Fe-doped ZnO composites can be obviously enhanced by upconversion luminescence agent (Er3+: YAlO3). Besides, the photocatalytic activity of Er3+: YAlO3/Fe-doped ZnO is better than that of Er3+: YAlO3/Co-doped ZnO. The influence of experiment conditions, such as the concentration of Er3+: YAlO3, heat-treatment temperature and time on the photocatalytic activity of the Er3+: YAlO3/Co- and Fe-doped ZnO coated composites was studied. In addition, the effects of solar light irradiation time, dye initial concentration, Er3+: YAlO3/Co- and Fe-doped ZnO amount on the photocatalytic degradation of azo fuchsine in aqueous solution were investigated in detail. Simultaneously, some other organic dyes, such as Methyl Orange (MO), Rhodamine B (RM-B), Acid Red B (AR-B), Congo Red (CR), and Methyl Blue (MB) were also studied. The possible excitation principle of Er3+: YAlO3/Co- and Fe-doped ZnO coated composites under solar light irradiation and the photocatalytic degradation mechanism of organic dyes were discussed.

  17. Metal Doped Manganese Oxide Thin Films for Supercapacitor Application.

    Science.gov (United States)

    Tung, Mai Thanh; Thuy, Hoang Thi Bich; Hang, Le Thi Thu

    2015-09-01

    Co and Fe doped manganese oxide thin films were prepared by anodic deposition at current density of 50 mA cm(-2) using the electrolyte containing manganese sulfate and either cobalt sulfate or ferrous sulfate. Surface morphology and crystal structure of oxides were studied by scanning electron microscope (SEM) and X-ray diffraction (XRD). Chemical composition of materials was analyzed by X-ray energy dispersive spectroscope (EDS), iodometric titration method and complexometric titration method, respectively. Supercapacitive behavior of Co and Fe doped manganese oxide films were characterized by cyclic voltammetry (CV) and impedance spectroscopy (EIS). The results show that the doped manganese oxides are composed of nano fiber-like structure with radius of 5-20 nm and remain amorphous structure after heat treatment at 100 degrees C for 2 hours. The average valence of manganese increases from +3.808 to +3.867 after doping Co and from +3.808 to +3.846 after doping Fe. The doped manganese oxide film electrodes exhibited preferably ideal pseudo-capacitive behavior. The specific capacitance value of deposited manganese oxide reaches a maximum of 175.3 F/g for doping Co and 244.6 F/g for doping Fe. The thin films retained about 84% of the initial capacity even after 500 cycles of charge-discharge test. Doping Co and Fe decreases diffusion and charge transfer resistance of the films. The electric double layer capacitance and capacitor response frequency are increased after doping.

  18. Doping of graphene induced by boron/silicon substrate

    Science.gov (United States)

    Dianat, Arezoo; Liao, Zhongquan; Gall, Martin; Zhang, Tao; Gutierrez, Rafael; Zschech, Ehrenfried; Cuniberti, Gianaurelio

    2017-05-01

    In this work, we show the doping of graphene most likely from heteroatoms induced by the substrate using Raman spectra, x-ray photoelectron spectroscopy, energy dispersive x-ray spectroscopy and ab initio molecular dynamics (MD) simulations. The doping of graphene on a highly boron-doped silicon substrate was achieved by an annealing at 400 K for about 3 h in an oven with air flow. With the same annealing, only the Raman features similar to that from the pristine graphene were observed in the freestanding graphene and the graphene on a typical Si/SiO2 wafer. Ab initio MD simulations were performed for defected graphene on boron-doped silicon substrate at several temperatures. All vacancy sites in the graphene are occupied either with B atoms or Si atoms resulting in the mixed boron-silicon doping of the graphene. The MD simulations validated the experimetal finding of graphene doped behavior observed by Raman spectrum. The electronic structure analysis indicated the p-type nature of doped graphene. The observed doping by the possible incorporation of heteroatoms into the graphene, simply only using 400 K annealing the boron-doped Si substrate, could provide a new approach to synthesize doped graphene in a more economic way.

  19. Synthesis and characterization of magnetic nanoparticles of oxides for dual MnFe{sub 2}O{sub 4} bioseparation, stabilized in fatty acid and the system chitosan - Eu(TTA){sub 3}(TPPO){sub 2}. Studies on the influence of doping with Gd{sup 3+}, Tb{sup 3+}, Ho{sup 3+} e Eu{sup 3+} in structural and magnetic properties; Sintese e caracterizacao de nanoparticulas magneticas de oxidos duplos de MnFe{sub 2}O{sub 4} para biosseparacao, estabilizadas em acido graxo e recobertas pelo sistema quitosana - Eu(TTA){sub 3}(TPPO){sub 2}. Estudo da influencia da dopagem com Gd{sup 3+}, Tb{sup 3+}, Ho{sup 3+} e Eu{sup 3+} nas propriedades estruturais e magneticas

    Energy Technology Data Exchange (ETDEWEB)

    Kovacs, Thelma Antunes Rodrigues

    2014-07-01

    This work was synthesized and characterized ferrite magnetic nanoparticles manganese, using the chemical coprecipitation method. By varying the heating time under 98°C (0, 10,20,40,60 3 80 minutes), the molar percentage of doping (1, 3, 5, 7, and 10%), gadolinium, europium, terbium and holmium. Magnetic ferrite nanoparticles and manganese ferrite doped with manganese were synthesized by coprecipitation method starting with chloride solutions of metals (iron (III), manganese (II), europium (III), gadolinium (III), terbium (III) and holmium (III)) and NaOH 5mol.L{sup -1} as precipitating agent. The magnetic nanoparticles were characterized by scanning electron microscopy, infrared spectroscopy, X-ray diffraction, magnetization curves, and thermal analysis. Most of manganese ferrite particles showed superparamagnetic behavior. After the characterization it was found that the samples synthesized manganese ferrite with more than 40 minutes heating time, crystal structure showed the characteristic pattern of the inverted manganese ferrite spinel type. The stabilization of the samples in oleic acid nanoparticles produced with a hydrophobic outer layer and facilitated by coating chitosan biopolymer, since this has a positive charge. Among the doped samples there was no significant change in the magnetic behavior. Several techniques for characterizing these materials have been used such as X-ray diffraction spectrum in the infrared region, magnetization curves and thermal analysis. The resins were tested as magnetic material for the separation of biological materials. In this paper, are used as biological targets separation of bovine serum albumin. (author)

  20. Attitudes and doping: a structural equation analysis of the relationship between athletes' attitudes, sport orientation and doping behaviour

    Directory of Open Access Journals (Sweden)

    Petróczi Andrea

    2007-11-01

    Full Text Available Abstract Background For effective deterrence methods, individual, systemic and situational factors that make an athlete or athlete group more susceptible to doping than others should be fully investigated. Traditional behavioural models assume that the behaviour in question is the ultimate end. However, growing evidence suggests that in doping situations, the doping behaviour is not the end but a means to an end, which is gaining competitive advantage. Therefore, models of doping should include and anti-doping policies should consider attitudes or orientations toward the specific target end, in addition to the attitude toward the 'tool' itself. Objectives The aim of this study was to empirically test doping related dispositions and attitudes of competitive athletes with the view of informing anti-doping policy developments and deterrence methods. To this end, the paper focused on the individual element of the drug availability – athlete's personality – situation triangle. Methods Data were collected by questionnaires containing a battery of psychological tests among competitive US male college athletes (n = 199. Outcome measures included sport orientation (win and goal orientation and competitiveness, doping attitude, beliefs and self-reported past or current use of doping. A structural equation model was developed based on the strength of relationships between these outcome measures. Results Whilst the doping model showed satisfactory fit, the results suggested that athletes' win and goal orientation and competitiveness do not play a statistically significant role in doping behaviour, but win orientation has an effect on doping attitude. The SEM analysis provided empirical evidence that sport orientation and doping behaviour is not directly related. Conclusion The considerable proportion of doping behaviour unexplained by the model suggests that other factors play an influential role in athletes' decisions regarding prohibited methods

  1. Attitudes and doping: a structural equation analysis of the relationship between athletes' attitudes, sport orientation and doping behaviour.

    Science.gov (United States)

    Petróczi, Andrea

    2007-11-09

    For effective deterrence methods, individual, systemic and situational factors that make an athlete or athlete group more susceptible to doping than others should be fully investigated. Traditional behavioural models assume that the behaviour in question is the ultimate end. However, growing evidence suggests that in doping situations, the doping behaviour is not the end but a means to an end, which is gaining competitive advantage. Therefore, models of doping should include and anti-doping policies should consider attitudes or orientations toward the specific target end, in addition to the attitude toward the 'tool' itself. The aim of this study was to empirically test doping related dispositions and attitudes of competitive athletes with the view of informing anti-doping policy developments and deterrence methods. To this end, the paper focused on the individual element of the drug availability - athlete's personality - situation triangle. Data were collected by questionnaires containing a battery of psychological tests among competitive US male college athletes (n = 199). Outcome measures included sport orientation (win and goal orientation and competitiveness), doping attitude, beliefs and self-reported past or current use of doping. A structural equation model was developed based on the strength of relationships between these outcome measures. Whilst the doping model showed satisfactory fit, the results suggested that athletes' win and goal orientation and competitiveness do not play a statistically significant role in doping behaviour, but win orientation has an effect on doping attitude. The SEM analysis provided empirical evidence that sport orientation and doping behaviour is not directly related. The considerable proportion of doping behaviour unexplained by the model suggests that other factors play an influential role in athletes' decisions regarding prohibited methods. Future research, followed by policy development, should incorporate these factors to

  2. Ascorbic Acid

    Science.gov (United States)

    Ascorbic acid is used to prevent and treat scurvy, a disease caused by a lack of vitamin C ... Ascorbic acid comes in extended-release (long-acting) capsules and tablets, lozenges, syrup, chewable tablets, and liquid drops ...

  3. Acid mucopolysaccharides

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003368.htm Acid mucopolysaccharides To use the sharing features on this page, please enable JavaScript. Acid mucopolysaccharides is a test that measures the amount ...

  4. Mefenamic Acid

    Science.gov (United States)

    Mefenamic acid is used to relieve mild to moderate pain, including menstrual pain (pain that happens before or during a menstrual period). Mefenamic acid is in a class of medications called NSAIDs. ...

  5. Obeticholic Acid

    Science.gov (United States)

    Obeticholic acid is used alone or in combination with ursodiol (Actigall, Urso) to treat primary biliary cholangitis (PBC; a ... were not treated successfully with ursodiol alone. Obeticholic acid is in a class of medications called farnesoid ...

  6. Ethacrynic Acid

    Science.gov (United States)

    Ethacrynic acid, a 'water pill,' is used to treat swelling and fluid retention caused by various medical problems. It ... Ethacrynic acid comes as a tablet to take by mouth. It is usually taken once or twice a day ...

  7. Amino acids

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002222.htm Amino acids To use the sharing features on this page, please enable JavaScript. Amino acids are organic compounds that combine to form proteins . ...

  8. Rational hybrid modulation of P, N dual-doped holey graphene for high-performance supercapacitors

    Science.gov (United States)

    Nazarian-Samani, Masoud; Haghighat-Shishavan, Safa; Nazarian-Samani, Mahboobeh; Kim, Myeong-Seong; Cho, Byung-Won; Oh, Si-Hyoung; Kashani-Bozorg, Seyed Farshid; Kim, Kwang-Bum

    2017-12-01

    A P, N dual-doped holey graphene (PNHG) material is prepared by a scalable, facile synthetic approach, using a mixture of glucose, dicyandiamide (DCDA), and phosphoric acid (H3PO4). H3PO4 successfully functions as an "acid catalyst" to encourage the uniform breakage of C=C bonds to create large, localized perforations over the graphene monolith. Further acid treatment and annealing introduce in-plane holes. The correlation between the capacitance of the PNHG and its structural parameters during the fabrication process is comprehensively evaluated. A thermally induced sp2→sp3 transformation occurs at high temperatures because of the substantial loss of graphitic sp2-type carbons, together with a dramatic reduction in capacitance. The target PNHG-400 electrode material delivers exceptionally high gravimetric capacitance (235.5 F g-1 at 0.5 A g-1), remarkable rate capability (84.8% at 70 A g-1), superior capacitance retention (93.2 and 92.7% at 10 and 50 A g-1 over 25000 cycles, respectively), and acceptable volumetric capacitance due to moderate density, when it is used with organic electrolytes in the voltage range between 0 and 3 V. These results suggest a pioneering defect-engineered strategy to fabricate dual-doped holey graphene with valuable structural properties for high-performance electric double layer supercapacitors, which could be used in next-generation energy storage applications.

  9. Study on the doping effect of Sn-doped ZnO thin films

    Science.gov (United States)

    Ajili, Mejda; Castagné, Michel; Turki, Najoua Kamoun

    2013-01-01

    Tin doped zinc oxide (ZnO:Sn) thin films were deposited onto Pyrex glass substrates by chemical spray pyrolysis technique starting from zinc acetate (CH3CO2)2Znṡ2H2O and tin chloride SnCl2. The effect of Sn doping on structural, optical and electrical properties was investigated. The atomic percentages of dopant in ZnO-based solution were y = [Sn4+]/[Zn2+] = 0%, 0.2%, 0.6% and 1%. It was found that all the thin films have a preferential c-axis orientation. With increase of Sn doping, the peak position of the (0 0 2) plane was shifted to the high 2θ values. ZnO:Sn demonstrated obviously improved surface roughness, reduced average crystallite size, enhanced Hall mobility and reduced resistivity. Among all of the tin doped zinc oxide in this study, films doped with 0.6 at.% Sn concentration exhibited the best properties, namely a Hall mobility of 9.22 cm2 V-1 s-1, an RMS roughness of 37.15 nm and a resistivity of 8.32 × 10-2 Ω cm.

  10. N-Doped Graphene with Low Intrinsic Defect Densities via a Solid Source Doping Technique

    Directory of Open Access Journals (Sweden)

    Bo Liu

    2017-09-01

    Full Text Available N-doped graphene with low intrinsic defect densities was obtained by combining a solid source doping technique and chemical vapor deposition (CVD. The solid source for N-doping was embedded into the copper substrate by NH3 plasma immersion. During the treatment, NH3 plasma radicals not only flattened the Cu substrate such that the root-mean-square roughness value gradually decreased from 51.9 nm to 15.5 nm but also enhanced the nitrogen content in the Cu substrate. The smooth surface of copper enables good control of graphene growth and the decoupling of height fluctuations and ripple effects, which compensate for the Coulomb scattering by nitrogen incorporation. On the other hand, the nitrogen atoms on the pre-treated Cu surface enable nitrogen incorporation with low defect densities, causing less damage to the graphene structure during the process. Most incorporated nitrogen atoms are found in the pyrrolic configuration, with the nitrogen fraction ranging from 1.64% to 3.05%, while the samples exhibit low defect densities, as revealed by Raman spectroscopy. In the top-gated graphene transistor measurement, N-doped graphene exhibits n-type behavior, and the obtained carrier mobilities are greater than 1100 cm2·V−1·s−1. In this study, an efficient and minimally damaging n-doping approach was proposed for graphene nanoelectronic applications.

  11. N-Doped Graphene with Low Intrinsic Defect Densities via a Solid Source Doping Technique.

    Science.gov (United States)

    Liu, Bo; Yang, Chia-Ming; Liu, Zhiwei; Lai, Chao-Sung

    2017-09-30

    N-doped graphene with low intrinsic defect densities was obtained by combining a solid source doping technique and chemical vapor deposition (CVD). The solid source for N-doping was embedded into the copper substrate by NH₃ plasma immersion. During the treatment, NH₃ plasma radicals not only flattened the Cu substrate such that the root-mean-square roughness value gradually decreased from 51.9 nm to 15.5 nm but also enhanced the nitrogen content in the Cu substrate. The smooth surface of copper enables good control of graphene growth and the decoupling of height fluctuations and ripple effects, which compensate for the Coulomb scattering by nitrogen incorporation. On the other hand, the nitrogen atoms on the pre-treated Cu surface enable nitrogen incorporation with low defect densities, causing less damage to the graphene structure during the process. Most incorporated nitrogen atoms are found in the pyrrolic configuration, with the nitrogen fraction ranging from 1.64% to 3.05%, while the samples exhibit low defect densities, as revealed by Raman spectroscopy. In the top-gated graphene transistor measurement, N-doped graphene exhibits n-type behavior, and the obtained carrier mobilities are greater than 1100 cm²·V -1 ·s -1 . In this study, an efficient and minimally damaging n-doping approach was proposed for graphene nanoelectronic applications.

  12. Doped Halloysite Nanotubes for Use in the 3D Printing of Medical Devices.

    Science.gov (United States)

    Weisman, Jeffery A; Jammalamadaka, Udayabhanu; Tappa, Karthik; Mills, David K

    2017-12-15

    Previous studies have established halloysite nanotubes (HNTs) as viable nanocontainers capable of sustained release of a variety of antibiotics, corrosion agents, chemotherapeutics and growth factors either from their lumen or in outer surface coatings. Accordingly, halloysite nanotubes (HNTs) hold great promise as drug delivery carriers in the fields of pharmaceutical science and regenerative medicine. This study explored the potential of 3D printing drug doped HNT constructs. We used a model drug, gentamicin (GS) and polylactic acid (PLA) to fabricate GS releasing disks, beads, and pellets. Gentamicin was released from 3D printed constructs in a sustained manner and had a superior anti-bacterial growth inhibition effect that was dependent on GS doping concentration. While this study focused on a model drug, gentamicin, combination therapy is possible through the fabrication of medical devices containing HNTs doped with a suite of antibiotics or antifungals. Furthermore, tailored dosage levels, suites of antimicrobials, delivered locally would reduce the toxicity of individual agents, prevent the emergence of resistant strains, and enable the treatment of mixed infections.

  13. Doped Halloysite Nanotubes for Use in the 3D Printing of Medical Devices

    Directory of Open Access Journals (Sweden)

    Jeffery A. Weisman

    2017-12-01

    Full Text Available Previous studies have established halloysite nanotubes (HNTs as viable nanocontainers capable of sustained release of a variety of antibiotics, corrosion agents, chemotherapeutics and growth factors either from their lumen or in outer surface coatings. Accordingly, halloysite nanotubes (HNTs hold great promise as drug delivery carriers in the fields of pharmaceutical science and regenerative medicine. This study explored the potential of 3D printing drug doped HNT constructs. We used a model drug, gentamicin (GS and polylactic acid (PLA to fabricate GS releasing disks, beads, and pellets. Gentamicin was released from 3D printed constructs in a sustained manner and had a superior anti-bacterial growth inhibition effect that was dependent on GS doping concentration. While this study focused on a model drug, gentamicin, combination therapy is possible through the fabrication of medical devices containing HNTs doped with a suite of antibiotics or antifungals. Furthermore, tailored dosage levels, suites of antimicrobials, delivered locally would reduce the toxicity of individual agents, prevent the emergence of resistant strains, and enable the treatment of mixed infections.

  14. Application of N-doped graphene modified carbon ionic liquid electrode for direct electrochemistry of hemoglobin

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Wei, E-mail: swyy26@hotmail.com [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China); Dong, Lifeng, E-mail: donglifeng@qust.edu.cn [College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Department of Physics, Astronomy, and Materials Science, Missouri State University, Springfield, MO 65897 (United States); Deng, Ying; Yu, Jianhua [College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Wang, Wencheng [College of Chemistry and Chemical Engineering, Hainan Normal University, Haikou 571158 (China); Zhu, Qianqian [College of Materials Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China)

    2014-06-01

    Nitrogen-doped graphene (NG) was synthesized and used for the investigation on direct electrochemistry of hemoglobin (Hb) with a carbon ionic liquid electrode as the substrate electrode. Due to specific characteristics of NG such as excellent electrocatalytic property and large surface area, direct electron transfer of Hb was realized with enhanced electrochemical responses appearing. Electrochemical behaviors of Hb on the NG modified electrode were carefully investigated with the electrochemical parameters calculated. The Hb modified electrode exhibited excellent electrocatalytic reduction activity toward different substrates, such as trichloroacetic acid and H{sub 2}O{sub 2}, with wider dynamic range and lower detection limit. These findings show that NG can be used for the preparation of chemically modified electrodes with improved performance and has potential applications in electrochemical sensing. - Graphical abstract: The utilization of N-doped graphene enables direct electrochemistry of hemoglobin with a pair of well-defined redox peaks appearing. - Highlights: • Nitrogen-doped graphene (NG) was synthesized by a solvothermal method. • NG was used for the investigation on direct electrochemistry of hemoglobin with carbon ionic liquid electrode. • The Hb modified electrode exhibited excellent electrocatalytic activity toward different substrates.

  15. Mn doped MoS2/reduced graphene oxide hybrid for enhanced hydrogen evolution

    Science.gov (United States)

    Wu, Liqian; Xu, Xiaobing; Zhao, Yuqi; Zhang, Kaiyu; Sun, Yuan; Wang, Tingting; Wang, Yuanqi; Zhong, Wei; Du, Youwei

    2017-12-01

    The hybrid material of Mn-doped molybdenum disulfide/reduced graphene oxide (Mn-MoS2/rGO) is successfully fabricated through a one-pot hydrothermal method. The hybrid material, evaluated as electrochemical catalyst for the hydrogen evolution reaction (HER), exhibits improved catalytic activity and good stability for the HER in acidic medium with small overpotential (approximately 110 mV). Through analyses, it can be concluded that the improvement for electrochemical HER performance of the hybrid catalyst is ascribed not only to high conductivity mainly from reduced graphene oxide, but also to fundamental catalytic activity enhancement generated by Mn ions doping into the S-edge of MoS2 with a portion of Mo ions replacement. These results verify the facilitation effect of Mn-doping on HER activities, and the Mn-MoS2/rGO hybrid prepared in this work could be employed as a promising alternative to noble metal catalysts in HER.

  16. Stimulated emission of sulforhodamine 640 doped DNA distributed feedback (DFB) laser devices

    Science.gov (United States)

    Yu, Zhou; Zhou, Yaling; Klotzkin, David J.; Grote, James G.; Steckl, Andrew J.

    2007-02-01

    Organic solid thin films of PMMA and surfactant-treated salmon deoxyribonucleic acid (DNA) were used as host materials to dope sulforhodamine (SRh) laser dye. Amplified Spontaneous Emission (ASE) was observed from the dye-doped thin films pumped by frequency-doubled Nd:YAG laser, with DNA host showed a lower ASE pump threshold. Distributed feedback (DFB) laser structures were fabricated on both dye-doped thin films for the 2 nd order emission of SRh at 650 nm. Stimulated Emission (Lasing) was obtained by pumping with a doubled Nd:YAG laser at 532 nm. The DNA DFB devices lasing threshold was 30μJ/cm2 or 3.75kW/cm2. The emission linewidth decreased from ~ 30 nm in the ASE mode to < 0.4 nm in the lasing mode. The slope efficiency of the laser emission was ~ 1.2%. Similar emission linewidth change was observed in PMMA DFB devices while the lasing threshold was 53 μJ/cm2 or 6.63kW/cm2 with a slope efficiency of ~0.63%.

  17. Fe doped TiO2 nanofibers on the surface of graphene sheets for photovoltaics applications

    Science.gov (United States)

    Farhangi, Nasrin; Medina-Gonzalez, Yaocihuatl; Charpentier, Paul A.

    2011-08-01

    Highly ordered, visible light driven TiO2 nanowire arrays doped with Fe photocatalysts were grown on the surface of functionalized graphene sheets (FGSs) using a sol-gel method with titanium isopropoxide (TIP) monomer, acetic acid (HAc) as the polycondensation agent and iron chloride in the green solvent, supercritical carbon dioxide (scCO2). The morphology of the synthesized materials was studied by SEM and TEM, which showed uniform formation of Fe doped TiO2 nanofibers on the surface of graphene sheets, which acted as a template for nanowire growth through surface -COOH functionalities. Increasing Fe content in the nanowires did not change the morphology significantly. Optical properties of the synthesized composites were examined by UV spectroscopy which showed a significant reduction in band gap with increasing Fe content, i.e. 2.25 eV at 0.6% Fe. The enhancement of the optical properties of synthesized materials was confirmed by photocurrent measurement. The optimum sample containing 0.6% Fe doped TiO2 on the graphene sheets increased the power conversation efficiency by 6-fold in comparison to TiO2 alone.

  18. Enhanced Photocatalytic Activity of Iron-Doped ZnO Nanowires for Water Purification

    Directory of Open Access Journals (Sweden)

    Yamina Ghozlane Habba

    2017-11-01

    Full Text Available In order to improve the photocatalytic efficiency of ZnO nanowires, iron-doped ZnO nanowires (ZnO:Fe NWs were successfully synthesized. The morphology, optical properties and photocatalytic performance of ZnO:Fe NWs were studied by scanning electron microscopy (SEM, UV-Visible spectrophotometry and photoluminescence spectroscopy (PL, respectively. The SEM observations showed that the morphology of the ZnO NWs was not modified by iron doping, but the band gap was reduced from 3.29 eV for ZnO NWs to 3.25 eV for ZnO:Fe NWs. This band gap reduction allows the semiconductor to harvest more photons to excite more electrons in the valence band; subsequently, resulting in an improvement of the degradability of the understudied organic dyes: methylene blue (MB, methyl orange (MO, and acid red 14 (AR14. The photocatalytic study showed that the photo-degradation rate of the MB, MO, and AR14 was improved 9%, 20%, and 5% respectively by 1% iron doping in the ZnO NWs.

  19. Cobalt Oxide on N-Doped Carbon for 1-Butene Oligomerization to Produce Linear Octenes

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Dongting [Department; Xu, Zhuoran [Department; Chada, Joseph P. [Department; Carrero, Carlos A. [Department; Rosenfeld, Devon C. [The Dow Chemical Company, 2301 N. Brazosport Boulevard, Freeport, Texas 77541-3257, United States; Rogers, Jessica L. [The Dow Chemical Company, 2301 N. Brazosport Boulevard, Freeport, Texas 77541-3257, United States; Hermans, Ive [Department; Huber, George W. [Department

    2017-10-02

    Cobalt oxide supported on N-doped carbon catalysts were investigated for 1-butene oligomerization. The materials were synthesized by treating activated carbon with nitric acid and subsequently with NH3 at 200, 400, 600, and 800 °C, followed by impregnation with cobalt. The 1-butene oligomerization selectivity increased with ammonia treatment temperature of the carbon support. The oligomerization selectivity of cobalt oxide on N-doped carbon synthesized at 800 °C (800A-CoOx/N-C) is 2.6 times higher than previously reported cobalt oxide on N-doped carbon synthesized with NH4OH (2A-CoOx/N-C). Over 70% of the butene dimers were linear C8 olefins for all catalysts. The oligomerization selectivity increased with 1-butene conversion. The catalysts were characterized by elemental analysis, N2 adsorption, X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), and X-ray photoelectron spectroscopy (XPS). The nitrogen content of the catalysts increases with ammonia treatment temperature as confirmed by elemental analysis. The surface content of pyridinic nitrogen with a binding energy of 398.4 ± 0.1 eV increased with ammonia treatment temperature as evidenced by deconvolution of N 1s XPS spectra.

  20. Sports doping in the adolescent: the Faustian conundrum of Hors de Combat.

    Science.gov (United States)

    Greydanus, Donald E; Patel, Dilip R

    2010-06-01

    The drive toward success in sports and the need for a cosmetically acceptable appearance have driven many adolescents to take a wide variety of so-called doping substances. The consumption of these chemicals in the hope and hype of improved sports performance, fueled by the easing of government restrictions on their proof of safety and efficacy, has resulted in an explosion of so-called ergogenic products available to our youth. Agents that have been used include anabolic steroids, anabolic-like agents, designer steroids, creatine, protein and amino acid supplements, minerals, antioxidants, stimulants, blood doping, erythropoietin, beta-blockers, and others. The use of these agents has considerable potential to cause physical and psychological damage. Use and misuse of drugs in this sports doping process should be discouraged. This discussion reviews some of the agents that are currently being used. Clinicians providing sports medicine care to youth, whether through anticipatory guidance or direct sports medicine management, should educate their young patients about the hype and hyperbole of these products that may keep them out instead of in the game at considerable financial cost to the unwary consumer.