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Publisher: Hindawi   (Total: 334 journals)

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Journal Cover Journal of Materials
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  This is an Open Access Journal Open Access journal
   ISSN (Print) 2314-4866 - ISSN (Online) 2314-4874
   Published by Hindawi Homepage  [334 journals]
  • Investigating Phase Transform Behavior in Indium Selenide Based RAM and
           Its Validation as a Memory Element

    • Abstract: Phase transform properties of Indium Selenide (In2Se3) based Random Access Memory (RAM) have been explored in this paper. Phase change random access memory (PCRAM) is an attractive solid-state nonvolatile memory that possesses potential to meet various current technology demands of memory design. Already reported PCRAM models are mainly based upon Germanium-Antimony-Tellurium (Ge2Sb2Te5 or GST) materials as their prime constituents. However, PCRAM using GST material lacks some important memory attributes required for memory elements such as larger resistance margin between the highly resistive amorphous and highly conductive crystalline states in phase change materials. This paper investigates various electrical and compositional properties of the Indium Selenide (In2Se3) material and also draws comparison with its counterpart mainly focusing on phase transform properties. To achieve this goal, a SPICE model of In2Se3 based PCRAM model has been reported in this work. The reported model has been also validated to act as a memory cell by associating it with a read/write circuit proposed in this work. Simulation results demonstrate impressive retentivity and low power consumption by requiring a set pulse of 208 μA for a duration of 100 μs to set the PCRAM in crystalline state. Similarly, a reset pulse of 11.7 μA for a duration of 20 ns can set the PCRAM in amorphous state. Modeling of In2Se3 based PCRAM has been done in Verilog-A and simulation results have been extensively verified using SPICE simulator.
      PubDate: Thu, 22 Sep 2016 16:14:58 +000
       
  • Composites: Preparation and Magnetodielectric Properties

    • Abstract: Cobalt ferrite (CoFe2O4) and silica (SiO2) nanopowders have been prepared by the microwave hydrothermal (M-H) method using metal nitrates as precursors of CoFe2O4 and tetraethyl orthosilicate as a precursor of SiO2. The synthesized powders were characterized by XRD and FESEM. The () (CoFe2O4) + SiO2 (where = 0%, 10%, 20%, and 30%) composites with different weight percentages have been prepared using ball mill method. The composite samples were sintered at 800°C/60 min using the microwave sintering method and then their structural and morphological studies were investigated using X-ray diffraction (XRD), Fourier transformation infrared (FTIR) spectra, and scanning electron microscopy (SEM), respectively. The effect of SiO2 content on the magnetic and electrical properties of CoFe2O4/SiO2 nanocomposites has been studied via the magnetic hysteresis loops, complex permeability, permittivity spectra, and DC resistivity measurements. The synthesized nanocomposites with adjustable grain sizes and controllable magnetic properties make the applicability of cobalt ferrite even more versatile.
      PubDate: Wed, 21 Sep 2016 14:30:19 +000
       
  • Synthesis and Study of CdS Thin Films Prepared with Different KMnO4
           Activation Time

    • Abstract: The growth and properties of cadmium sulfide (CdS) thin films were prepared in a controlled manner using chemical bath deposition (CBD) method for different KMnO4 activation time such as 5 min, 10 min, 15 min, 20 min, 25 min, and 30 min on glass substrates. CdS thin films are deposited on KMnO4 activated glass substrates at 85°C with pH value of 10 for 30 min deposition time. In the chemical bath deposition (CBD) technique, KMnO4 activation time plays an important role in the growth of the CdS film. The structure of the CdS film changes with respect to the rate of deposition. The size of the particles is affected by the nucleation rate if the solution does not contain the constant number of Cd2+ and S2− ions throughout the deposition process. This change in structure of CdS is confirmed by the XRD, SEM, and AFM analysis, and the ion-by-ion nucleation growth is also examined. The optical property of the prepared CdS thin film is scrutinized using UV-Vis-NIR absorption analysis.
      PubDate: Tue, 30 Aug 2016 14:08:03 +000
       
  • Synthesis of 14-Aryl-14H-dibenzo[a,j]xanthene Derivatives Using H-Zeolite
           A as an Efficient and Reusable Catalyst under Solvent-Free Condition

    • Abstract: H-Zeolite A is an efficient, excellent, and reusable catalyst for the synthesis of 14-aryl-14H-dibenzo[a,j]xanthene derivatives by one-pot synthesis of β-naphthol with various aromatic aldehyde derivatives under solvent-free condition. The synthesized zeolite H-Zeolite A was characterized by XRD, SEM, and FT-IR. The synthesized products were characterized by FT-IR and 1H-NMR spectra. Simple workup procedure, short reaction time, high yield, and reusability of the catalyst are the characteristic features of these reactions.
      PubDate: Mon, 29 Aug 2016 11:15:09 +000
       
  • Analyses of Short Channel Effects of Single-Gate and Double-Gate Graphene
           Nanoribbon Field Effect Transistors

    • Abstract: Short channel effects of single-gate and double-gate graphene nanoribbon field effect transistors (GNRFETs) are studied based on the atomistic orbital model for the Hamiltonian of graphene nanoribbon using the nonequilibrium Green’s function formalism. A tight-binding Hamiltonian with an atomistic orbital basis set is used to describe the atomistic details in the channel of the GNRFETs. We have investigated the vital short channel effect parameters such as and , the threshold voltage, the subthreshold swing, and the drain induced barrier lowering versus the channel length and oxide thickness of the GNRFETs in detail. The gate capacitance and the transconductance of both devices are also computed in order to calculate the intrinsic cut-off frequency and switching delay of GNRFETs. Furthermore, the effects of doping of the channel on the threshold voltage and the frequency response of the double-gate GNRFET are discussed. We have shown that the single-gate GNRFET suffers more from short channel effects if compared with those of the double-gate structure; however, both devices have nearly the same cut-off frequency in the range of terahertz. This work provides a collection of data comparing different features of short channel effects of the single gate with those of the double gate GNRFETs. The results give a very good insight into the devices and are very useful for their digital applications.
      PubDate: Thu, 25 Aug 2016 07:00:22 +000
       
  • Thermal and Dielectric Behavior Studies of Poly(Arylene Ether Sulfone)s
           with Sulfonated and Phosphonated Pendants

    • Abstract: The present paper discusses the aspects of the synthesizing valeric acid based poly(ether sulfone)s with active carboxylic acid pendants (VALPSU) from solution polymerization technique via nucleophilic displacement polycondensation reaction among 4,4′-dichlorodiphenyl sulfone (DCDPS) and 4,4′-bis(4-hydroxyphenyl) valeric acid (BHPA). The conditions necessary to synthesize and purify the polymer were investigated in some detail. The synthesized poly(ether sulfone)s comprise sulfone and ether linkages in addition to reactive carboxylic acid functionality; these active carboxylic acid functional groups were exploited to hold the phenyl sulphonic acid and phenyl phosphonic acid pendants. The phenyl sulphonic acid pendants in VALPSU were easily constructed by altering active carboxylic acid moieties by sulfanilic acid using N,N′-dicyclohexylcarbodiimide (DCC) mediated mild synthetic route, whereas the latter one was built in two steps. Initially, polyphosphoric acid condensation with VALPSU by 4-bromoaniline and next straightforward palladium catalyzed synthetic route, in both of which acidic pendants are clenched by polymer backbone via amide linkage. Without impairing the primary polymeric backbone modified polymers were prepared by varying the stoichiometric ratios of respective combinations. All the polymers were physicochemically characterized and pressed into tablets; electrical contacts were established to study the dielectric properties. Finally, the influence of the acidic pendants on the dielectric properties was examined.
      PubDate: Wed, 24 Aug 2016 11:58:32 +000
       
  • CNT Reinforced Silver Nanocomposites: Mechanical and Electrical Studies

    • Abstract: Nanoindentation hardness and elastic modulus of the silver/MWCNT (multiwalled carbon nanotubes) composites, fabricated by modified wet mixing technique, are studied in the present work. CNT reinforced silver nanocomposites, fabricated by introducing 4.5 volume percentages of CNT in the silver matrix, have increased elastic modulus and approximately 50% higher hardness than pure nanosilver. It is also observed from the results that the electrical conductivity of the fabricated materials was decreased by increasing the CNTs volume %.
      PubDate: Wed, 17 Aug 2016 13:02:10 +000
       
  • The Energy Loss of α-Particles in Ferromagnetic Nickel at Phase
           Transition

    • Abstract: The energy loss (EL) of 5.486 MeV α-particles in ferromagnetic nickel foils was measured at different temperatures of the foils. The temperature of the foils was controlled and recorded using a PC-based temperature controller with an accuracy of ±0.01°C. It is observed that the energy loss in ferromagnetic nickel increases by 2–5% as the material goes from ferromagnetic to paramagnetic state. Thus our results show that the phase transition in ferromagnetic materials affects energy loss.
      PubDate: Wed, 17 Aug 2016 09:47:00 +000
       
  • Enhancement of Light Localization in Hybrid Thue-Morse/Periodic Photonic
           Crystals

    • Abstract: The electric field intensity in one-dimensional (1D) quasiperiodic and hybrid photonics band-gap structures is studied in the present paper. The photonic structures are ordered according to Fibonacci, Thue-Morse, Cantor, Rudin-Shapiro, Period-Doubling, Paper-Folding, and Baum-Sweet sequences. The study shows that the electric field intensity is higher for the Thue-Morse multilayer systems. After that the Thue-Morse structure will be combined with a periodic structure to form a hybrid photonic structure. It is shown that this hybrid system is the best for a strong localization of light. The proposed structures have been modeled using the Transfer Matrix Method.
      PubDate: Sun, 14 Aug 2016 11:31:06 +000
       
  • Optimization of Cutting Parameters during Dry Turning of Austenitic
           Stainless Steel Using nc-AlTiN/Si3N4, TiAlN, and TiN Coated Inserts

    • Abstract: The nc-AlTiN/Si3N4, TiAlN, and TiN coating were deposited using lateral rotating cathodes (LARC) technology on TNMG 160404 cemented carbide turning inserts. Ultrafine grain treated cemented carbide substrates were used in case of TiAlN and TiN inserts. The coated inserts were tested for their hardness and compositions were determined by X-ray diffraction studies. The grain structures of coatings were observed using scanning electron microscopy. Dry cutting tests were performed on AISI 304 stainless steel to compare the performances of these coatings in terms of wear and surface finish imparted to workpiece. 3D confocal laser microscope was used to determine the flank wear. Grey relation analysis was carried out to optimize the machining parameters. Studies reveal that nc-AlTiN/Si3N4 coating showed the highest hardness of 28 GPa. The coating also shows a dense grain structure. Furthermore, in cutting tests even under severe dry cutting conditions, the wear observed was less than the other two coatings and surface finish imparted to work parts was less than 2 μm by this coating.
      PubDate: Thu, 28 Jul 2016 09:19:39 +000
       
  • Cement Pastes and Mortars Containing Nitrogen-Doped and
           Oxygen-Functionalized Multiwalled Carbon Nanotubes

    • Abstract: Cement pastes and mortars based on ordinary Portland cement containing nitrogen-doped multiwalled carbon nanotubes (MWCNT-Nx) or oxygen-functionalized multiwalled carbon nanotubes (MWCNT-Ox) are investigated. To incorporate MWCNTs into the cementitious matrix, the as-produced carpets are dispersed over periods of 1 and 2 hours in distilled water at pH levels of 1 and 7. The cement pastes are prepared by adding 0.1 wt% of MWCNTs to cement powder, followed by characterization with SEM and X-ray diffraction (XRD) at an early age (first hours of hydration). The mortars are mechanically characterized during the hydration process for a period of 28 days. SEM characterization of cement pastes revealed that the carbon nanotubes are well incorporated in the cementitious matrix, with the hydrated cement grains interconnected by long carbon nanotubes. XRD characterizations demonstrated that, during the hydration of cement pastes, different peaks emerged that were associated with ettringite, hydrated calcium silicate, and calcium hydroxide, among other structures. Results of the compressive strength measurements for mortars simultaneously mixed with MWCNT-Nx and MWCNT-Ox reached an increment of approximately 30% in compressive strength. In addition, density functional theory calculations were performed in nitrogen-doped and oxygen-functionalized carbon nanotubes interacting with a cement grain.
      PubDate: Sun, 28 Feb 2016 08:45:22 +000
       
  • Influence of Grain Boundary Character and Annealing Time on Segregation in
           Commercially Pure Nickel

    • Abstract: Commercially pure nickel (Ni) was thermomechanically processed to promote an increase in Σ3 special grain boundaries. Engineering the character and chemistry of Σ3 grain boundaries in polycrystalline materials can help in improving physical, chemical, and mechanical properties leading to improved performance. Type-specific grain boundaries (special and random) were characterized using electron backscatter diffraction and the segregation behavior of elements such as Si, Al, C, O, P, Cr, Mg, Mn, B, and Fe, at the atomic level, was studied as a function of grain boundary character using atom probe tomography. These results showed that the random grain boundaries were enriched with impurities to include metal oxides, while Σ3 special grain boundaries showed little to no impurities at the grain boundaries. In addition, the influence of annealing time on the concentration of segregants on random grain boundaries was analyzed and showed clear evidence of increased concentration of segregants as annealing time was increased.
      PubDate: Tue, 16 Feb 2016 08:55:29 +000
       
  • Behavioural Change according to the Si/Al Ratio of Successive
           Na-Mordenites Observed through Their Dielectric Relaxation during Water
           Vapour Adsorption Process

    • Abstract: The experimental study of water vapour adsorption phenomenon on a zeolite, by dielectric relaxation measurement, makes it possible to determine the variations in the exchangeable cation hopping activation energy, on the surface of the solid, in relation to the number of adsorbed molecules. The present work shows that it is possible to explain the change observed in the energy, by means of simple assumptions based, on the one hand, on the models used in order to simulate the adsorption process and, on the other hand, on the distribution of the molecules adsorbed near the exchangeable cations. Thus, the phenomenological interpretation suggested here, about the change in the exchangeable cation hopping energy, obtained by dielectric relaxation measurement, makes us with a mind to conceive a simple method for explaining the results leading to new information on the organization of the first adsorbed molecules on the surface of the studied zeolite. Then, it can be verified that these conclusions confirm the assumptions already developed for interpreting the inferences from previous experiments carried out by means of other techniques.
      PubDate: Wed, 03 Feb 2016 13:03:23 +000
       
  • Investigation of the Physical and Molecular Properties of Asphalt Binders
           Processed with Used Motor Oils

    • Abstract: In this work we investigated the performance aspects of addition of used motor oils (UMO) to neat and crumb rubber modified asphalts (CRMA) and related that to the change of molecular size distribution of modified asphalt’s fractions; asphaltenes, saturates, naphthene aromatics, and polar aromatics. Based on the results of temperature sweep viscoelastic tests, addition of crumb rubber modifier (CRM) alone or with UMO results in the formation of internal network within the modified asphalt. Based on the results of short and long term aged asphalts, the utilization of combination of UMO and CRM enhanced the aging behavior of asphalt. Bending beam rheometer was utilized to investigate the low temperature behavior of UMO modified asphalts. Based on those tests, the utilization of the UMO and CRM enhanced the low temperature properties of asphalts. Based on the results of the asphalt separation tests and the Gel Permeation Chromatography (GPC) analysis, it was found that saturates and naphthene aromatics are the two asphalt fractions that have similar molecular size fractions as those of UMO. However, UMO only shifts the molecular sizes of saturates after interaction with asphalt. Results also show that polar aromatics pose higher molecular size structures than UMO.
      PubDate: Mon, 21 Dec 2015 06:27:40 +000
       
  • Structural and Thermophysical Studies of Composite Na-Cobaltite
           Electrospun Nanofibers

    • Abstract: Polymeric nanofibers have been produced in the last few years by electrospinning of polymer solutions. Polyvinyl alcohol (PVA) was the selected polymer for the preparation of nanofibers. Processing parameters like flow rate, needle gauge, needle to collector distance, and molarity of the solution have been optimized during electrospinning process. Sol-gel method has been used for the preparation of thermoelectric cobaltite nanoparticles having composition NaCoO2. Sol-gel combined electrospinning technique was used to prepare the composites of the NaCoO2 with PVA nanofibers. X-ray diffraction (XRD), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) have been used for the structural analysis of the prepared samples. Scanning electron microscopy (SEM) was used to observe the morphology of the prepared fibers. SEM micrographs showed that, by increasing the flow rate, diameter of the fibers increased from 185 nm to 200 nm. Two-probe method and Advantageous Transient Plane Source (ATPS) were used to study the electrical and thermal transport properties, respectively. Thermal conductivity and electrical conductivity showed a direct dependence on temperature. It was observed that particles, sample has lower thermal conductivity (0.610 W/m-K) as compared to that of composite nanofibers (1.129 W/m-K). The measurements reported are novel and are useful for energy applications.
      PubDate: Sun, 15 Nov 2015 08:11:31 +000
       
  • Structural Characteristics and Magnetic Properties of Al2O3 Matrix-Based
           Co-Cermet Nanogranular Films

    • Abstract: Magnetic micro- and nanogranular materials prepared by different methods have been used widely in studies of magnetooptical response. However, among them there seems to be nothing about magnetic nanogranular thin films prepared by a cosputtering technique for both metals and insulators till now. This paper presented and discussed preparation, structural characteristics, and magnetic properties of alumina () matrix-based granular Co-cermet thin films deposited by means of the cosputtering technique for both Co and . By varying the ferromagnetic (Co) atomic fraction, , from 0.04 to 0.63, several dominant features of deposition for these thin films were shown. Structural characteristics by X-ray diffraction confirmed a cermet-type structure for these films. Furthermore, magnetic behaviours presented a transition from paramagnetic- to superparamagnetic- and then to ferromagnetic-like properties, indicating agglomeration and growth following Co components of Co clusters or nanoparticles. These results show a typical granular Co-cermet feature for the Co- thin films prepared, in which Co magnetic nanogranules are dispersed in a ceramic matrix. Such nanomaterials can be applied suitably for our investigations in future on the magnetooptical responses of spinplasmonics.
      PubDate: Wed, 11 Nov 2015 09:29:33 +000
       
  • Early-Age Strength Measurement of Shotcrete

    • Abstract: Shotcrete or sprayed concrete is a special concrete designed for spraying onto a surface, as a construction material. With shotcrete application as a ground support system ever-present in both mining and tunnelling sectors, a major requirement of drive progression is to determine when it is safe to reenter beneath freshly sprayed concrete. Accurately determining this time is of paramount importance. Generally, this reentry time is based on measuring the developing strength of shotcrete until an adequate strength value is reached. The issue with current practice is that there is no widely accepted or generally preferred method that accurately assesses the shotcrete lining’s true early-age strength. However, there are a number of strength tests that are commercially available and used in the industry; these include the soil penetrometer, needle penetrometer, bolt screws, beam end testers, and drilled core samples. This paper researches into these testing methods and their characteristics in order to determine their accuracy, testing ranges, and suitability for in situ use in the tunnelling and mining industry. The investigation ultimately reveals that current methods all have substantial shortcomings. Based on these findings, recommendations are proposed for the applicable use of the current testing methods and recommendations for future improvements.
      PubDate: Tue, 10 Nov 2015 09:16:44 +000
       
  • Diclofenac Potassium Transdermal Patches Using Natural Rubber Latex
           Biomembranes as Carrier

    • Abstract: The aim of this study was to design a compound transdermal patch containing diclofenac potassium (Dic-K) using natural rubber latex (NRL) biomembrane. The NRL from Hevea brasiliensis is easily manipulated and low cost and presents high mechanical resistance. It is a biocompatible material which can stimulate natural angiogenesis and is capable of adhering cells on its surface. Recent researches have used the NRL for Transdermal Drug Delivery Systems (TDDSs). Dic-K is used for the treatment of rheumatoid arthritis and osteoarthritis and pain relief for postoperative and posttraumatic cases, as well as inflammation and edema. Results showed that the biomembrane can release Dic-K for up to 216 hours. The kinetics of the Dic-K release could be fitted with double exponential function. X-ray diffraction and Fourier Transform Infrared (FTIR) spectroscopy show some interaction by hydrogen bound. The results indicated the potential of the compound patch.
      PubDate: Sun, 08 Nov 2015 15:49:46 +000
       
  • Biodegradation Study of Nanocomposites of Phenol Novolac Epoxy/Unsaturated
           Polyester Resin/Egg Shell Nanoparticles Using Natural Polymers

    • Abstract: Nanocomposite materials refer to those materials whose reinforcing phase has dimensions on a scale from one to one hundred nanometers. In this study, the nanocomposite biodegradation of the phenol Novolac epoxy and the unsaturated polyester resins was investigated using the egg shell nanoparticle as bioceramic as well as starch and glycerin as natural polymers to modify their properties. The phenol Novolac epoxy resin has a good compatibility with the unsaturated polyester resin. The prepared samples with different composition of materials for specified time were buried under soil and their biodegradation was studied using FTIR and SEM. The FTIR results before and after degradation showed that the presence of the hydroxyl group increased the samples degradation. Also adding the egg shell nanoparticle to samples had a positive effect on its degradation. The SEM results with and without the egg shell nanoparticle also showed that use of the egg shell nanoparticle increases the samples degradation. Additionally, increasing the amount of starch, and glycerol and the presence of egg shell nanoparticles can increase water adsorption.
      PubDate: Sun, 08 Nov 2015 12:28:48 +000
       
  • Removal of Indigo Carmine Dye from Aqueous Solution Using Magnesium
           Hydroxide as an Adsorbent

    • Abstract: Magnesium hydroxide is used as an adsorbent for the removal of indigo carmine dye from aqueous solution. We have investigated the effectiveness of removal of indigo carmine dye from aqueous solutions at pH 6-7 and 12-13 using magnesium hydroxide thereby varying the dose of the adsorbent, concentration of the dye, duration, and temperature. Structural transformations of adsorbent during the adsorption process at different pH values are monitored using powder X-ray diffraction and infrared spectroscopy. Different types of adsorption isotherm models were evaluated and it was found that Langmuir isotherm fits well at both pH values (6-7 and 12-13). Adsorption of indigo carmine onto magnesium hydroxide at pH 6-7/pH 12-13 follows pseudo-second order rate kinetics.
      PubDate: Sun, 01 Nov 2015 09:46:48 +000
       
  • Plasma Induced Physicochemical Changes and Reactive Dyeing of Wool Fabrics

    • Abstract: This study focuses on the effect of dielectric barrier discharge (DBD) plasma treatment on physical and chemical properties of wool fabric and its relation to exhaustion of Drimalan Navy Blue FBI reactive dye. AFM analysis of plasma treated wool fabric has shown partial removal of epicuticle and thus reduced scale height. FD spectroscopy has shown improvement in hydrophilicity by many folds after plasma treatment. ATR graphs depict the removal of hydrophobic layer of 18-MEA and introduction of hydrophilic groups like cysteic acid after plasma treatment. Alkali solubility of wool fabric increases with increasing plasma treatment time. Wetting time for plasma treated fabric reduces drastically when compared to untreated wool fabric. It is found that plasma treated fabric takes much lesser time to reach maximum dye exhaustion than untreated fabric. Substantivity of the dye increases significantly after plasma treatment. Colour fastness properties improve with increase in plasma treatment time. Chemical oxygen demand (COD) of spent dyebath liquor is found to reduce with increase in plasma treatment time. Biological oxygen demand (BOD) is found to be higher for plasma treated samples, while ratio of COD/BOD has reduced with increase in the plasma treatment time.
      PubDate: Tue, 27 Oct 2015 13:46:11 +000
       
  • Synthesis and Characterization of Vanadium Doped Zinc Oxide Thick Film for
           Chemical Sensor Application

    • Abstract: Zinc oxide and vanadium pentoxide nanoparticles derived by chemical coprecipitation route were used to cast Zn0.96V0.04O thick film by screen printing method. The structural, morphological, optical, and electrical properties of the film were characterized by powder XRD, SEM, Raman, UV-VIS, and DC conductivity techniques. XRD pattern, SEM image, and Raman spectrum of the film confirm the single phase formation of Wurtzite structure with preferential orientation along [] plane, minor variation in lattice parameters, and vanadium ions substitution at zinc sites. Zn0.96V0.04O pellet has been used for sensing ammonia vapor concentrations in 20–50°C temperature range which exhibits maximum responsiveness and sensitivity at 30°C. The minor variations in resistance are observed with ammonia vapor concentration. The adsorption of ammonia vapors through weak hydrogen bonding and its insertion into lattice by nitrogen lone pairs donation at vacant/defect sites in lattice caused by vanadium doping are considered to explain gas sensing mechanism.
      PubDate: Mon, 26 Oct 2015 11:44:46 +000
       
  • Molecular Dynamics Study on Lubrication Mechanism in Crystalline Structure
           between Copper and Sulfur

    • Abstract: To clarify the nanosized mechanism of good lubrication in copper disulfide (Cu2S) crystal which is used as a sliding material, atomistic modeling of Cu2S is conducted and molecular dynamics (MD) simulations are performed in this paper. The interatomic interaction between atoms and crystalline structure in the phase of hexagonal crystal of Cu2S are carefully estimated by first-principle calculations. Then, approximating these interactions, we originally construct a conventional interatomic potential function of Cu2S crystal in its hexagonal phase. By using this potential function, we perform MD simulation of Cu2S crystal which is subjected to shear loading parallel to the basal plane. We compare results obtained by different conditions of sliding directions. Unlike ordinary hexagonal metallic crystals, it is found that the easy-glide direction does not always show small shear stress for Cu2S crystal. Besides, it is found that shearing velocity affects largely the magnitude of averaged shear stress. Generally speaking, higher velocity results in higher resistance against shear deformation. As a result, it is understood that Cu2S crystal exhibits somewhat liquid-like (amorphous) behavior in sliding condition and shear resistance increases with increase of sliding speed.
      PubDate: Mon, 26 Oct 2015 08:45:43 +000
       
  • Strength Performance Based on Flexibility from Laterite Soil Using Tire
           Powder and Micro Silica

    • Abstract: In terms of environmental issues and human health, one of the advisable techniques to improve soil behavior is the use of scrap tires for soil structures. According to the literature, Tire-Derived Aggregates (TDA) are one of the valuable materials in different field of Geotechnical that can be used. TDA properties correspond to some important factors such as high level of flexible, lightweight, high permeability and economic material comparing with sand. Strength performance based on increasing flexibility from laterite soil is the main goal of this study. For this purpose, tropical laterite soil was mixed using TDA and micro silica (MS). As a research method, unconfined tests were carried for thirteen samples based on different percentage of the additives. As a result, the significant reduction for elasticity modulus and strength was observed when soil mixed just using TDA. In addition, the rate of strain at the peak of the curve was dramatically increased. The best performance was found using 6% additives when the ratio was 3% MS and 3% TDA. In fact, the effect of MS was more to increase strength. To recommend, the seepage controlling will investigate at next.
      PubDate: Mon, 26 Oct 2015 06:17:57 +000
       
  • Rutherford Backscattering Spectrometry Analysis and Structural Properties
           of Thin Films Deposited by Chemical Spray Pyrolysis

    • Abstract: Zinc lead sulphide ternary thin films were prepared by chemical spray pyrolysis on soda lime glass substrates using zinc acetate, lead acetate, and thiourea sources precursor. The films were characterized using Rutherford backscattering (RBS) spectrometry, energy dispersive X-ray (EDX) spectroscopy, scanning electron microscopy (SEM), and X-ray diffractometry (XRD). RBS studies revealed variation in thickness and stoichiometry of the films with respect to compositional substitution between Zn and Pb, thereby giving effective composition , where , 0.035, 0.069, 0.109, 0.176, and 0.217. Film thickness obtained by length conversion ranged from 81.02 nm to 90.03 nm. Microstructural analyses also indicated that the growth and particle distribution of the films were uniform across substrate’s surface. Diffraction studies showed that the films possess FCC crystalline structure. Crystallite size reduced from 14.28 to 9.8 nm with increase in Zn2+ in the samples.
      PubDate: Thu, 08 Oct 2015 07:27:17 +000
       
  • Effect of Lateral Substitution on the Electronics and Phase Transitions of
           Stilbazoles, Benzoic Acids, Phenols, and Hydrogen Bonded Mixtures

    • Abstract: The preparation and characterization of laterally substituted 4-alkoxy-stilbazoles, 4-alkoxy-benzoic acids, and 4-alkoxy phenols and hydrogen bonded heterodimeric mixtures of these compounds are reported. Lateral substitution has a minimal effect on the ring electronics of 4-alkoxy benzoic acids and 4-alkoxy phenols; however the ring electronics of stilbazole units is extremely sensitive to lateral substitution. While lateral substitution is an effective technique for lowering the melting points of both hydrogen bonded complexes and their individual components, its effect on the electronics of stilbazoles and steric disruption of both intermolecular hydrogen bonding and molecular packing in the solid state disrupts the formation of liquid crystalline phases in both the individual components and hydrogen bonded complexes.
      PubDate: Wed, 07 Oct 2015 09:00:28 +000
       
  • Photocatalytic Degradation of Eosin Yellow Using
           Poly(pyrrole-co-aniline)-Coated TiO2/Nanocellulose Composite under Solar
           Light Irradiation

    • Abstract: The present study describes the feasibility of a novel adsorbent cum photocatalyst, poly(pyrrole-co-aniline)-coated TiO2/nanocellulose composite (P(Py-co-An)-TiO2/NCC), to remove eosin yellow (EY) from aqueous solutions. The removal of EY was investigated by batch adsorption followed by photocatalysis. The effect of various adsorption parameters like adsorbent dose, pH, contact time, initial concentration, and ionic strength has been optimized for treating effluents from the dye industry. Adsorption of EY reached maximum at pH 4.5 and complete removal of dye was achieved using 3.5 g/L of P(Py-co-An)-TiO2/NCC. Adsorption equilibrium data were fitted with Langmuir and Fritz-Schlunder isotherm models and the kinetics of adsorption follows a second-order mechanism. The adsorption capacity of P(Py-co-An)-TiO2/NCC was found to be 3.39 × 10−5 mol/g and reached equilibrium within 90 min. The photocatalytic degradation of adsorbed dye under sunlight was possible and about 92.3% of dye was degraded within 90 min. The reusability of P(Py-co-An)-TiO2/NCC was also investigated. The results indicate that P(Py-co-An)-TiO2/NCC is the best material for the wiping out of EY from aqueous solutions.
      PubDate: Sun, 04 Oct 2015 13:38:41 +000
       
  • Chopped Strand/Plain Weave E-Glass as Reinforcement in Vacuum Bagged Epoxy
           Composites

    • Abstract: Polymer matrix composites are one of the materials being extensively researched and are gaining a lot of importance due to advantages like high specific strength, greater flexibility in design, and reduced cost of manufacturing. In this study, tensile, flexural, impact, and interlaminar shear strength of chopped strand/plain weave E-glass composites were considered. Composite laminates with different stacking sequence were fabricated using Vacuum Assisted Resin Infusion Moulding (VARIM) technique. Fiber volume fractions (FVF) of 22%, 26%, and 30% were adopted. Experiments were conducted in accordance with ASTM standards. Results indicate that laminates with three layers of plain weave mat exhibited better tensile, flexural, and interlaminar shear strength. However, laminates with two layers of chopped strand mat and one layer of plain weave mat showed improved impact resistance. In addition, scanning electron microscopy was used to analyze the fracture surface.
      PubDate: Sun, 13 Sep 2015 11:24:21 +000
       
  • On the Synthesis of Molybdenum Nanoparticles under Reducing Conditions in
           Ionic Liquids

    • Abstract: We report on attempts to synthesize Mo nanoparticles under reducing conditions in ionic liquids (ILs). Ionic liquids were based on the 1-ethyl-3-methylimidazolium or 1-butyl-3-methylimidazolium (Emim and Bmim, resp.) cations and the dicyanamide N(CN)2, triflate (OTf), bis(trifluoromethylsulfonyl)imide-(NTf2), tetrafluoroborate (BF4), ethyl sulfate (ES), and methylsulfonate (MS) anions. (NH4)6Mo7O24∗4H2O and NaBH4 were reacted in a set of imidazolium ionic liquids (ILs) at 180°C to evaluate the potential of the ILs for stabilization of metallic Mo nanoparticles. XRD and TEM reveal a strong influence of the IL anion on the particle sizes, shapes, and crystal structures. The influence of the IL cation and the reaction temperature is much less pronounced.
      PubDate: Thu, 10 Sep 2015 13:06:56 +000
       
  • MATLAB User Interface for Simulation of Silicon Germanium Solar Cell

    • Abstract: Nuclear fusion reaction on the sun is the largest source of energy. In this paper, qualitative investigation of the numerical model of silicon germanium heterojunction solar cell is performed using MATLAB graphical user interface. The heterostructure is designed as for speculative determination of appropriate germanium mole fraction to get the maximized thin-film solar cell efficiency (ή). Other characteristics such as absorption coefficient (α), energy band gap (), reflectivity (r), open circuit voltage (), and generation rate are also considered. This user interface will reduce the complexity of solving differential equation for the analysis of silicon germanium heterojunction cell.
      PubDate: Mon, 17 Aug 2015 12:19:10 +000
       
 
 
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