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    - CHEMICAL ENGINEERING (154 journals)
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    - ENGINEERING (1117 journals)
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ENGINEERING (1117 journals)            First | 2 3 4 5 6 7 8 9 | Last

International Journal of Manufacturing Research     Hybrid Journal   (Followers: 6)
International Journal of Manufacturing Technology and Management     Hybrid Journal   (Followers: 8)
International Journal of Materials and Product Technology     Hybrid Journal   (Followers: 4)
International Journal of Mathematical Education in Science and Technology     Hybrid Journal   (Followers: 7)
International Journal of Mathematics in Operational Research     Hybrid Journal   (Followers: 1)
International Journal of Medical Engineering and Informatics     Hybrid Journal   (Followers: 5)
International Journal of Micro Air Vehicles     Full-text available via subscription   (Followers: 4)
International Journal of Microwave and Wireless Technologies     Hybrid Journal   (Followers: 1)
International Journal of Microwave Science and Technology     Open Access   (Followers: 2)
International Journal of Mobile Network Design and Innovation     Hybrid Journal   (Followers: 3)
International Journal of Multiphase Flow     Hybrid Journal   (Followers: 2)
International Journal of Nanomanufacturing     Hybrid Journal   (Followers: 1)
International Journal of Nanoscience     Hybrid Journal   (Followers: 1)
International Journal of Nanotechnology     Hybrid Journal   (Followers: 5)
International Journal of Navigation and Observation     Open Access   (Followers: 6)
International Journal of Network Management     Hybrid Journal  
International Journal of Nonlinear Sciences and Numerical Simulation     Full-text available via subscription   (Followers: 1)
International Journal of Numerical Methods for Heat & Fluid Flow     Hybrid Journal   (Followers: 7)
International Journal of Optics     Open Access   (Followers: 1)
International Journal of Organisational Design and Engineering     Hybrid Journal   (Followers: 9)
International Journal of Pattern Recognition and Artificial Intelligence     Hybrid Journal   (Followers: 6)
International Journal of Pavement Engineering     Hybrid Journal   (Followers: 2)
International Journal of Physical Modelling in Geotechnics     Hybrid Journal   (Followers: 3)
International Journal of Plasticity     Hybrid Journal   (Followers: 6)
International Journal of Plastics Technology     Hybrid Journal  
International Journal of Polymer Analysis and Characterization     Hybrid Journal   (Followers: 4)
International Journal of Polymer Science     Open Access   (Followers: 16)
International Journal of Precision Engineering and Manufacturing     Hybrid Journal   (Followers: 6)
International Journal of Precision Technology     Hybrid Journal  
International Journal of Pressure Vessels and Piping     Hybrid Journal   (Followers: 2)
International Journal of Production Economics     Hybrid Journal   (Followers: 10)
International Journal of Quality and Innovation     Hybrid Journal   (Followers: 4)
International Journal of Quality Engineering and Technology     Hybrid Journal   (Followers: 2)
International Journal of Quantum Information     Hybrid Journal  
International Journal of Rapid Manufacturing     Hybrid Journal   (Followers: 2)
International Journal of Reliability, Quality and Safety Engineering     Hybrid Journal   (Followers: 5)
International Journal of Renewable Energy Technology     Hybrid Journal   (Followers: 8)
International Journal of Robust and Nonlinear Control     Hybrid Journal   (Followers: 2)
International Journal of Science Engineering and Advance Technology     Open Access  
International Journal of Sediment Research     Full-text available via subscription   (Followers: 1)
International Journal of Self-Propagating High-Temperature Synthesis     Hybrid Journal   (Followers: 2)
International Journal of Signal and Imaging Systems Engineering     Hybrid Journal  
International Journal of Six Sigma and Competitive Advantage     Hybrid Journal  
International Journal of Social Robotics     Hybrid Journal   (Followers: 1)
International Journal of Software Engineering and Knowledge Engineering     Hybrid Journal   (Followers: 1)
International Journal of Space Science and Engineering     Hybrid Journal   (Followers: 2)
International Journal of Speech Technology     Hybrid Journal   (Followers: 3)
International Journal of Spray and Combustion Dynamics     Full-text available via subscription   (Followers: 6)
International Journal of Surface Engineering and Interdisciplinary Materials Science     Full-text available via subscription   (Followers: 1)
International Journal of Surface Science and Engineering     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Engineering     Hybrid Journal   (Followers: 7)
International Journal of Sustainable Manufacturing     Hybrid Journal   (Followers: 4)
International Journal of Systems Assurance Engineering and Management     Hybrid Journal  
International Journal of Systems, Control and Communications     Hybrid Journal   (Followers: 2)
International Journal of Technology Management and Sustainable Development     Hybrid Journal   (Followers: 1)
International Journal of Technology Policy and Law     Hybrid Journal   (Followers: 4)
International Journal of Telemedicine and Applications     Open Access   (Followers: 2)
International Journal of Thermal Sciences     Hybrid Journal   (Followers: 5)
International Journal of Thermodynamics     Open Access   (Followers: 2)
International Journal of Turbo & Jet-Engines     Full-text available via subscription  
International Journal of Ultra Wideband Communications and Systems     Hybrid Journal  
International Journal of Vehicle Autonomous Systems     Hybrid Journal   (Followers: 1)
International Journal of Vehicle Design     Hybrid Journal   (Followers: 6)
International Journal of Vehicle Information and Communication Systems     Hybrid Journal   (Followers: 2)
International Journal of Vehicle Noise and Vibration     Hybrid Journal   (Followers: 3)
International Journal of Vehicle Safety     Hybrid Journal   (Followers: 4)
International Journal of Vehicular Technology     Open Access   (Followers: 2)
International Journal of Virtual Technology and Multimedia     Hybrid Journal   (Followers: 4)
International Journal of Wavelets, Multiresolution and Information Processing     Hybrid Journal  
International Journal on Artificial Intelligence Tools     Hybrid Journal   (Followers: 4)
International Nano Letters     Open Access   (Followers: 6)
International Review of Applied Sciences and Engineering     Full-text available via subscription  
Inverse Problems in Science and Engineering     Hybrid Journal   (Followers: 2)
Ionics     Hybrid Journal  
IPTEK The Journal for Technology and Science     Open Access  
IRBM News     Full-text available via subscription  
Irrigation and Drainage Systems     Hybrid Journal  
ISA Transactions     Full-text available via subscription   (Followers: 1)
ISRN - International Scholarly Research Notices     Open Access   (Followers: 69)
ISRN Nanotechnology     Open Access  
ISRN Signal Processing     Open Access  
ISRN Thermodynamics     Open Access  
IT Professional     Full-text available via subscription   (Followers: 3)
Journal of Biosensors & Bioelectronics     Open Access   (Followers: 1)
Journal of Advanced Manufacturing Systems     Hybrid Journal   (Followers: 7)
Journal of Aerosol Science     Hybrid Journal   (Followers: 2)
Journal of Aerospace Engineering     Full-text available via subscription   (Followers: 147)
Journal of Alloys and Compounds     Hybrid Journal   (Followers: 7)
Journal of Analytical and Applied Pyrolysis     Hybrid Journal   (Followers: 3)
Journal of Analytical Science & Technology     Open Access   (Followers: 4)
Journal of Analytical Sciences, Methods and Instrumentation     Open Access   (Followers: 1)
Journal of Applied Analysis     Full-text available via subscription  
Journal of Applied and Industrial Sciences     Open Access  
Journal of Applied Logic     Full-text available via subscription  
Journal of Applied Physics     Hybrid Journal   (Followers: 170)
Journal of Applied Probability     Full-text available via subscription   (Followers: 6)
Journal of Applied Research and Technology     Open Access  
Journal of Applied Science and Technology     Full-text available via subscription  
Journal of Applied Sciences     Open Access   (Followers: 5)
Journal of Architectural Engineering     Full-text available via subscription   (Followers: 6)

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Journal Cover Ionics
   Journal TOC RSS feeds Export to Zotero Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 1862-0760 - ISSN (Online) 0947-7047
     Published by Springer-Verlag Homepage  [2209 journals]   [SJR: 0.522]   [H-I: 25]
  • A sensitive amperometric detection of dopamine agonist drug pramipexole at
           functionalized multi-walled carbon nanotubes (f-MWCNTs) modified electrode
    • Abstract: Abstract The electrochemical detection of dopaminergic agonist drug pramipexole dihydrochloride monohydrate (PPX) has been investigated by cyclic voltammetric (CV) and amperometric i–t techniques at functionalized multi-walled carbon nanotubes-modified glassy carbon electrode. For the first time, a sensitive and rapid electrochemical method was developed for the determination of PPX. The surface morphological characteristics of the proposed electrode have been studied by using transmission electron microscopy (TEM); further, electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR) have been employed. PPX shows an irreversible anodic peak, which may be ascribed to the oxidation of the –NH groups of PPX. The proposed method was showing good sensitivity of 0.993 μA μM−1 cm−2 with a linear range of 5 to 340 μM by amperometric i–t and CV technique shows a linear range of 12.5 to 313 μM with a sensitivity of 1.92 μA μM−1 cm−2. The recovery of PPX from blood serum samples was found 100.6 and 98.9 %, respectively. Furthermore, the proposed method has been demonstrated for the determination of PPX in commercially available pharmaceutical samples and good agreement of results obtained.
      PubDate: 2014-11-01
  • The effect of different concentrations of Na 2 SnO 3 on the
           electrochemical behaviors of the Mg-8Li electrode
    • Abstract: Abstract In this research, the effect of the different concentrations of NaSnO3 as the electrolyte additive in 0.7 mol L−1 NaCl solution on the electrochemical performances of the magnesium-8lithium (Mg-8Li) electrode are investigated by methods of potentiodynamic polarization, potentiostatic current-time, electrochemical impedance technique, and scanning electron microscopy (SEM). The corrosion resistance of the Mg-8Li electrode is improved when Na2SnO3 is added into the electrolyte solution. The potentiostatic current-time curves show that the electrochemical behaviors of the Mg-8Li electrode in the electrolyte solution containing 0.20 mmol L−1 Na2SnO3 is the best. The electrochemical impedance spectroscopy results indicate that the polarization resistance of the Mg-8Li electrode decreases in the following order with the concentrations of Na2SnO3: 0.05 mmol L−1 > 0.00 mmol L−1 > 0.30 mmol L−1 > 0.10 mmol L−1 > 0.20 mmol L−1. The scanning electron microscopy studies indicate that the electrolyte additive prevents the formation of the dense oxide film on the alloy surface and facilitates the peeling off of the oxidation products.
      PubDate: 2014-11-01
  • LiFePO 4 /C composites derived from precipitated FePO 4 precursor: effects
           of mixing processes
    • Abstract: Abstract Grinding, general incipient wetness and competitive incipient wetness were investigated on the preparation of LiFePO4/C (LFP) composites from precipitated FePO4 precursor. This article focuses on the fundamental details of mixing processes for LFP production, of which the literature is sparse. The structure features of LiFePO4/C composites were analyzed by X-ray diffraction (XRD), while the morphologies were characterized by field emission scanning electron microscopy (FESEM). The electrochemical performances were studied by galvanostatic charge/discharge measurements. Both mixing processes and lithium sources are capable of affecting the electrochemical performances by altering the crystallinity, the quality of carbon coating, or even the impurity formation of LiFePO4/C composites. Liquid alkalis caused the formation of impurities and mild decrease of crystallinity, whereas competitive cations did not produce impurities but significantly decreased the crystallinity of LiFePO4/C composites.
      PubDate: 2014-11-01
  • Double-walled core-shell structured Si@SiO 2 @C nanocomposite as anode for
           lithium-ion batteries
    • Abstract: Abstract Double-walled core-shell structured Si@SiO2@C nanocomposite has been prepared by calcination of silicon nanoparticles in air and subsequent carbon coating. The obtained Si@SiO2@C nanocomposite demonstrates a reversible specific capacity of about 786 mAh g−1 after 100 cycles at a current density of 100 mA g−1 with a capacity fading of 0.13 % per cycle. The enhanced electrochemical performance can be due to that the double walls of carbon and SiO2 improve the electronic conductivity and enhance the compatibility of electrode materials and electrolyte as a result of accommodating the significant volumetric change during cycles. The interlayer SiO2 may release the mechanical strain and enhance the interfacial adhesion between carbon shell and silicon core.
      PubDate: 2014-11-01
  • Polypyrrole–NiO hybrid nanocomposite films: highly selective,
           sensitive, and reproducible NO 2 sensors
    • Abstract: Abstract Polypyrrole–nickel oxide (PPy–NiO) hybrid nanocomposite thin-film sensor was prepared by spin-coating method on glass substrate. The PPy–NiO hybrid nanocomposite thin film sensors were used to study room temperature gas-sensing properties for oxidizing (NO2, Cl2) as well as reducing (NO2, H2S, C2H5OH, NH3, and Cl2) gases. It was revealed that PPy–NiO (50 %) hybrid nanocomposite thin-film sensor could detect NO2 at low concentration (100 ppm) with very high selectivity (47 % compared with Cl2) and high sensitivity (47 %), with better stability (90 %) and reproducibility. The response and recovery times were changed significantly with NO2 concentration.
      PubDate: 2014-11-01
  • The effects of Li 2 CO 3 particle size on the properties of lithium
           titanate as anode material for lithium-ion batteries
    • Abstract: Abstract Spinel structured Li4Ti5O12 was synthesized by a solid-state method using TiO2 and Li2CO3 as starting materials. High-energy ball milling was used to obtain the Li2CO3 samples with different particle size. Then, the effects of Li2CO3 particle size on the structure, morphology, and electrochemical performance of Li4Ti5O12 samples were investigated in detail. The samples were characterized by TG/DTA analysis, X-ray diffraction, scanning electron microscopy and electrochemical tests, respectively. The results indicate that fine Li2CO3 particles will promote the interfacial reaction between Li2CO3 and TiO2 in solid-state reaction. The crystallinity and particle size of Li4Ti5O12 depend on the particle size of Li2CO3. Electrochemical tests show that Li4Ti5O12 samples synthesized by fine Li2CO3 particles exhibit better rate capacity and cycle performance.
      PubDate: 2014-11-01
  • Improving the electrochemistry and microstructure of nickel electrode by
           deposition on anodized titanium substrate for the electrocatalytic
           oxidation of methanol and ethanol
    • Abstract: Abstract The electrodeposition process of nickel and the substrate used for the electrodeposition can be improved to obtain an effective catalyst for methanol oxidation. Thus, nanoparticles of nickel have been uniformly electrodeposited on the surface of previously anodized titanium at 5 V during 1 h. The optimized microstructure has been studied by using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The XPS and argon-ion etching experiments have revealed the composition profile of the titanium/titania/nickel thin film electrode. Metallic Ni is detected by XRD. The nickel particles dispersed in a porous TiO2 substrate have great catalytic activity for methanol oxidation in basic solution and through the redox couple NiO(OH)/Ni(OH)2. The optimized titania substrate yields to electrodes (crystalline titanium/amorphous titania/nanocrystalline nickel) with higher catalytic activity than non-anodized metallic titanium (titanium/nickel). However, further oxidation and thickening of the titania film drives to poorer electrochemical behavior. The SEM and EDS results show that the nickel particles exhibit certain tendency to agglomerate and to form spherical particles of around 2 μm. This electrode material also is active to oxidize ethanol, but this activity is poorer.
      PubDate: 2014-11-01
  • Influence of fuel and media on membraneless sodium percarbonate fuel cell
    • Abstract: Abstract This paper reports the media flexibility of membraneless sodium percarbonate fuel cell (MLSPCFC) using acid/alkaline bipolar electrolyte in which the anode is in acidic media while the cathode is in alkaline media, or vice versa. Investigation of the cell operation is conducted by using formic acid as a fuel and sodium percarbonate as an oxidant for the first time under ‘acid–alkaline media’ configurations. The MLSPCFC architecture enables interchangeable operation with different media combinations. The experimental results indicate that operating under acid–alkaline media conditions significantly improves the fuel cell performance compared with all-acidic and all-alkaline conditions. The effects of flow rates and the concentrations of various species at both the anode and cathode on the cell performance are also investigated. It has been demonstrated that the laminar flow-based microfluidic membraneless fuel cell can reach a maximum power density of 25.62 mW cm−2 with a fuel mixture flow rate of 0.3 mL min−1 at room temperature.
      PubDate: 2014-11-01
  • Electrical properties of novel Li 4.08 Zn 0.04 Si 0.96 O 4 ceramic
           electrolyte at high temperatures
    • Abstract: Abstract Novel Li4.08Zn0.04Si0.96O4 electrolyte was synthesized by citric acid-assisted sol–gel method. The compound was studied by X-ray diffraction and complex impedance spectroscopy in the frequency range from 10 Hz to 10 MHz and temperature range from 573 to 773 K. The conductivity–frequency spectra exhibited two regions of conductivity dispersion related to Li+ ion transport in the bulk and grain boundaries. The activation energy of the bulk conductivity was found to be equal to the activation energy of relaxation frequency in the bulk. This indicated that the increase in conductivity with temperature was due to the increase in ion mobility while the number of charge carrier concentration was found to be constant with selected temperature range. The observation was in agreement with the calculated charge carrier concentration and ion mobility derived from conductance spectra, σ ac(ω) = σ o  + Aω α .
      PubDate: 2014-11-01
  • Electrical conductivity and dielectric relaxation studies of a polymeric
           hybrid compound: ([C 2 H 10 N 2 ]CdCl 2 (SCN) 2 ) n
    • Abstract: Abstract Electrical conductivity and dielectric measurements of ([C2H10N2]CdCl2(SCN)2)n were carried out from 200 Hz–5 MHz over a temperature range of 307–352 K. The frequency dependence of electrical data have been analyzed in two frameworks: the electrical modulus formalism with the Kohlrausch-Williams-Watts (KWW) stretched exponential function and the electrical conductivity by using the Jonscher’s power law σ′Tot(ω,T) = σDC(T) + A(T)ωs(T) in the frequency domain. The conduction mechanism is attributed to the nonoverlapping small polaron tunneling (NSPT) model. Furthermore, the dielectric data have also been analyzed in modulus and polarizability formalisms. The close values of activation energies obtained from the conductivity, the relaxation process, the electric modulus, and the complex polarizability data confirm that the transport is through ion-hopping mechanism.
      PubDate: 2014-11-01
  • Preparation and electrochemical performance of spherical MnO x with high
    • Abstract: Abstract A promising electrode material, MnOx, was prepared by chemical precipitation method using MnSO4 · H2O as manganese source and (NH4)2CO3 as precipitant. The as-prepared manganese oxide was characterized by field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and X-ray diffraction (XRD), respectively. The effects of reaction temperature and calcination temperature on the electrochemical properties of the electrode materials were investigated. The results show that MnOx with a spherical morphology exhibits an excellent performance in the energy storage field. Under the optimal experimental conditions, the specific capacitance of pure MnOx reaches up to 592 F g−2 in the alkaline media when the current density is 5 mA cm−2 over the potential window from −0.3 to +0.4 V. The combination resistance and transfer resistance of MnOx are 0.86 and 0.08 Ω, respectively. These findings make MnOx a promising electrode material for electrochemical capacitors.
      PubDate: 2014-11-01
  • Structure and electrochemical performance of LiCoO 2 cathode material in
           different voltage ranges
    • Abstract: Abstract LiCoO2 sample prepared by high-temperature solid state calcination shows a typical hexagonal structure with a single phase and fine particle size distribution. The high-voltage electrolyte with additive fluoroethylene carbonate (FEC) has been used. Electrochemical results show that the initial discharge capacities of the prepared LiCoO2 cathode are 157.7, 169.5, 191.0, and 217.5 mAh g−1 in the voltage ranges of 3.0–4.3, 3.0–4.4, 3.0–4.5, and 3.0–4.6 V, respectively. The capacity increases, while the initial coulombic efficiency and capacity retention decrease with increasing the charge cutoff voltage. The capacity retention is only 10.4 % after 200 cycles at 1C rate in the voltage range of 3.0–4.6 V. X-ray diffraction measurements confirm structural changes of the layered material in the different voltage ranges. A phase transition from the O3 to the H1-3 phase can be observed when LiCoO2 is charged above 4.5 V. The AC impedance analysis indicates that the resistances (R (sf+b), R ct) of the prepared LiCoO2 rapidly increase when the cell is charged to higher voltage. The amount of dissolved Co into the electrolyte also greatly increases with increasing the charge cutoff voltage.
      PubDate: 2014-11-01
  • Influences on power performances of metal oxide additives for LiFePO 4
    • Abstract: Abstract Metal oxide additives are added into LiFePO4 electrodes attempting to improve cell power performances. Electrochemical performances are tested with 5 wt% different sizes of neutral alumina, nano Al2O3, and nano MgO individually comparing with those with 5 wt% more active LiFePO4 and acetylene black. The polarization between charge and discharge plateaus is reduced not only by adding more conductive acetylene black, but also by adding all these insulated metal oxide additives. Adding natural alumina and nano MgO can significantly increase rate capacities. This might be because of their “lithium ion saver” effect.
      PubDate: 2014-11-01
  • Synthesis of LiCoPO 4 as cathode material for lithium-ion batteries by the
           rheological phase method
    • Abstract: Abstract LiCoPO4 has been successfully synthesized by a simple rheological phase method. The effects of synthesis temperature on the properties of LiCoPO4 are also investigated. The results show that a well-crystallized olivine structure LiCoPO4 with no obvious impurity phase is obtained. The electrochemical properties of LiCoPO4 were examined by galvanostatic charge/discharge tests, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The results indicate that the sintering temperature has a significant effect on the electrochemical properties of LiCoPO4. The sample fired at 600 °C shows the best electrochemical properties. The initial discharge capacity is 101.0, 96.8, and 91.6 mAh g−1 at 0.1, 0.2, and 1 C, respectively. The significantly improved electrochemical properties of LiCoPO4 are attributed to the better crystallized rheological phase production with better dispersed and smaller particles, which can greatly facilitate the diffusion of Li+.
      PubDate: 2014-11-01
  • Self-assembled 3D Co 3 O 4 -graphene frameworks with high lithium storage
    • Abstract: Abstract Three-dimensional Co3O4-graphene frameworks (3D-CGFs) are prepared with a one-pot hydrothermal method. Co3O4 particles are in situ anchored on graphene sheets, and the resulting composite self-assembles into 3D architecture during the hydrothermal treatment. Scanning electron microscope, transmission electron microscope, powder X-ray powder diffraction, and Raman spectroscopy are employed to characterize the sample. When tested as anode materials for lithium-ion batteries, 3D-CGFs demonstrate remarkable electrochemical lithium storage properties, such as large and stable reversible capacity (>530 mAh g−1 at 500 mA g−1 over 300 cycles), good capacity retention (88 % retention after 300 cycles at 500 mA g−1 compared with the 4th cycle), excellent high-rate performance (515 mAh g−1 at 1 A g−1), making it a promising candidate for high-performance anode materials, especially for high-rate lithium-ion batteries.
      PubDate: 2014-11-01
  • A comparative study on the effects of salt and filler on transport and
           structural properties of organic–inorganic hybrid electrolytes
    • Abstract: Abstract Organic–inorganic hybrid electrolytes based on the reaction of tri-block copolymer poly(propylene glycol)-block-poly(ethylene glycol)-block-poly(propylene glycol) bis(2-aminopropyl ether), poly(ethylene glycol diglycidyl ether, and (3-glycidyloxypropyl)trimethoxysilane doped with LiClO4 and SiO2 nanoparticles were synthesized by a sol–gel process. The structural and dynamic properties of the materials thus obtained were systematically investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, thermogravimetric analysis, alternate current impedance, and 13C solid-state NMR measurements. A maximum ionic conductivity of 3.2 × 10−5 S cm−1 was obtained at 30 °C for the solid hybrid electrolyte with a [O]/[Li] ratio of 16 and 7 wt% of SiO2 nanoparticles. A Vogel–Tamman–Fulcher-like temperature dependence of ionic conductivity was observed for the hybrid electrolytes, implying that the diffusion of charge carriers was assisted by the segmental motions of the polymer chains.
      PubDate: 2014-11-01
  • Silver-doped silver vanadate glass composite electrolyte: structure and an
           investigation of electrical properties
    • Abstract: Abstract Structural and electrical properties of the ternary ionic–electronic conducting glass system xAgI–(1 − x)[0.67Ag2O–0.33V2O5], where x = 0.4, 0.5, 0.6, 0.7, and 0.8 were studied for emphasizing the influence of silver iodide concentration on the transport properties of the based vanadate glasses. The glasses were prepared by melt quenching technique and characterized using X-ray diffraction (XRD), FTIR spectra, and differential thermal analysis (DTA). Electrical conductivity (σ), dielectric constant (ε′), dielectric loss (ε″), and impedance spectra (Z′-Z″) were studied for all samples. All glasses showed a mixed ionic–electronic conductance with a high ionic conductivity for the sample with x = 0.7. The electronic contribution to the total conductivity and the ionic (t i) and electronic transport numbers (t e) were determined for each glass sample using Wagner’s DC polarization technique. The variation in electrical properties with each of composition, temperature, and frequency was analyzed and discussed. Graphical Abstract AgI dopant (0.7 mol) created more opened vanadate network structure and enhanced both ion migration and orientation and as a result showed a high DC conductivity and ionic transfer number at room temperature.
      PubDate: 2014-10-29
  • Differential pulse voltammetric determination of methyldopa using MWCNTs
           modified glassy carbon decorated with NiFe 2 O 4 nanoparticles
    • Abstract: Abstract A nanosensor was introduced for a sensitive determination of methyldopa using multiwall carbon nanotubes (MWCNTs) decorated with ferrite nickel nanoparticles (NiFe2O4) on a glassy carbon electrode. The electrochemical activity of the modified electrode for the determination of methyldopa was investigated using differential pulse voltammetry, cyclic voltammetry, and electrochemical impedance spectroscopy. The results showed that the modified electrode exhibits synergistic activity to the oxidation of methyldopa. The influence of several parameters that affect the response of the modified electrode was studied. A wide linear dynamic range of 0.5 to 900 μmol L−1 methyldopa with a detection limit of 0.08 μmol L−1 was achieved using differential pulse voltammetry. The interference of foreign substances on the selectivity of the electrochemical sensor was evaluated. Finally, the proposed method was successfully applied for the determination of methyldopa in real samples such as human urine, tablet, and plasma with satisfactory results.
      PubDate: 2014-10-28
  • Effect of oxygen activity on semiconducting properties of TiO 2 (rutile)
    • Abstract: Abstract Intensive research aims to reduce the band gap of TiO2-based semiconductors by the incorporation of a range of cations and anions in order to enhance their performance in solar energy conversion. In this work, we show that the band gap, as well as the related semiconducting properties, may be modified by impositions of variable oxygen activity in the oxide lattice instead of doping with extrinsic ions. It is shown that the band gap may be decreased when TiO2 is annealed in strongly reducing conditions [p(O2) ∼10−12 Pa]. The reported data indicate that oxygen activity in the oxide lattice, including TiO2, is the key quantity which must be taken into account in considering compatibility and reproducibility of a range of properties, such as band gap and charge transport.
      PubDate: 2014-10-28
  • Research status in preparation of FePO 4 : a review
    • Abstract: Abstract The cathode is the most important component of a lithium-ion battery. The olivine structure lithium iron phosphate (LiFePO4) with its numerous appealing features, such as high theoretical capacity, acceptable operating voltage, increased safety, environmental benignity, and low cost, has attracted extensive interest as a potential cathode material for Li-ion batteries. As a precursor, FePO4 can be used to produce LiFePO4 on a large scale with high bulk density, discharge rate, and capacity. This can be realized by controlling the crystal size and morphology of FePO4. The characteristics, structure, and synthesis methods of FePO4 are discussed in this review. The relative merits of these synthetic methods, as well as some suggestions on how to improve them, are also presented.
      PubDate: 2014-10-03
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