bluuebunny/crossref_metadata_2025 huggingface dataset:
Investigation of HA Nanocrystallite Size Crystallographic Characterizations in NHA, BHA and HA Pure Powders and their Influence on Biodegradation of HA
Authors: Karamian Ebrahim , Khandan Amirsalar , Eslami Mustafa , Gheisari Hassan , Rafiaei Niosha
Published: November 2013

The mineral or inorganic component of bone is a calcium phosphate idealized as a calcium hydroxyapatite, HA, Ca10(PO4)6(OH)2. Changes in the composition of the apatite affect its lattice parameters, morphology, crystallinity (reflecting crystal size and/or perfection) and finally dissolution properties. In regard to the above points, lattice parameters are expected to have better dissolution properties. Estimation of HA nanocrystallite size lattice parameters is one of the most important factors for dissolution properties of bone apatites. In present work, the composition of apatite induce complex structures at the unit-cell level and play a role in influencing the dissolution rate of apatites, which may favour osteointegration. The samples are consist of NHA, bovine bone heated at 850 °C for 3 h; BHA, human bone heated at 900 oC for 2 h and PHA, HA pure powder. The results estimated by XRD data indicate that increasing in c/a ratio of HA, which is leading to increasing in crystallinity, induce decrease at HA dissolution or improving its chemical solubility in simulated body fluid (SBF). As, it was concluded that the biodegradation of HA decrease in PHA sample.
Electrodeposition of Gold and Polypyrrole Thin Films for Neural Microelectrodes
Authors: Kojabad Zohreh Deljoo , Sanjabi Sohrab , Shojaosadati Seyed Abbas
Published: November 2013

A low impedance electrode/tissue interface is critically important for neural microelectrodes recording to maintain signal quality. In this study, gold/polypyrrol thin films used to decrease the interface impedance. Gold thin film was electrodeposited by cyclic voltammetry in the potential range of-0.3 to 1 volt on the stainless steel surface of microelectrodes with 127 micrometer in radius. Then polypyrrole was electrodeposited on the gold layer. Electrochemical impedance spectroscopy tests were performed for impedance measurement of microelectrode surface. The effect of morphology and thickness on the impedance of thin film was studied. The results showed that the impedance of the microelectrodes with gold/polypyrrol coatings was 38.2% lower than the electrodes without coating in the neural frequency.
Study on the Hydrophobized Changes in Wettability of Sol-Gel Synthesized Nano Titanium Dioxide Films
Authors: Hosseini-Zori Maryam
Published: November 2013

The hydrophobized change in wettability of TiO2films has been investigated for glass coated with acidic TiO2nanosols containing varying concentrations of dispersed nanocrystalline titania, obtained by sol-gel method. The photo-induced change in wettability was evaluated by measuring the time dependent drop of water contact angle (WCA) after samples had been soaked in a decanoic acid (DA). TiO2films treated in this way exhibit superhydrophobic behaviour, with WCA greater than 1600. After radiation with UV (black light), the superhydrophobic properties are transformed into superhydrophilic properties, with WCA of almost 08. As TiO2content and layer thickness increase, high rates of photo-induced change are found. Use of a calcination temperature for the intermediate annealing of the single layers in multilayer coatings and a short final sintering step at a relatively high temperature (e.g. 500-700 °C for 10 min) allow the preparation of relatively thin TiO2 films on glass with a high photoactivity.
Study on the Fabrication of Superhydrophobic Microporous Polypropylene Flat Membrane Using In Situ Synthesis of Modified Fluorinated Silica Nano Particles
Authors: Raveshiyan Saba , Yegani Reza , Pourabbas Behzad , Tavakkoli Akram
Published: November 2013

The wettability is the most important features of membrane, when it works as contactors. Although the membrane contactors offer many advantages over conventional contacting equipments, additional mass transfer resistance is introduced when micropores are filled with aqueous absorbents. Therefore, fabrication of superhydrophobic membrane which prevents diffusion of aqueous absorbent into membrane pores is a highly challenging task. In this work, superhydrophobic polypropylene (PP) membrane was fabricated using in situ synthesis of silica nano particles via thermally induced phase separation (TIPS) method. Flat sheet fabricated PP membranes were casted with methanolic solution containing various ratios of perfluorooctyltriethoxysilane (PFOTES)/ tetraethylortosilicate (TEOS) and then sol-gel reaction between the mixed silances was completed. The contact angle of coated membrane was reached to 168 degree, when the percentage of PFOTES/TEOS was fixed at 50% (mol/mol). Interestingly, due to the microporous structure of PP membrane, the synthesized fluorinated silica nanoparticles were observed on the surface as well as in the cross-sectional area of the membrane. Field emission scanning electron microscopy (FE-SEM) images were confirmed this point. Chemical structure of the coated membranes with 50% PFOTES was compared with pure PP membrane using ATR-IR. In order to evaluate the operational performance, coated membranes were immersed in aqueous solutions of mono ethanol amine (MEA), di ethanol amine (DEA) and pure water. In comparison with pure PP membrane, obtained results showed that the wettability of coated membranes was considerably decreased.
The Effect of Cu Doping on LPG Response of the SnO2 Nanostructure Layer
Authors: Mirsalary Seyyedeh Esmat , Iranizad Esmaiel Saievar
Published: November 2013

In this research, the pure and Cu-doped SnO2 nanostructure layers covered on the glass substrate by sol-gel and spin coating methods. The composition, structure and surface morphology of these layers have been studied by energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM), respectively. The results of EDX analysis show that the Cu-doped SnO2 layer is a mixture of 4.97 wt% Copper and 95.03 wt% Tin elements. The images obtained from FESEM show existence of the particles about 50 nm and 38 nm for pure and Cu-doped SnO2 layers, respectively. Also the results obtained from XRD spectroscopy show that these layers have the tetragonal polycrystalline Tin dioxide structure. The response of these layers investigated for different concentrations of Liquid petroleum gas (LPG) by static gas sensing system. The results of this investigation show that the Cu-doped SnO2 nanostructure layer compared with the pure SnO2 nanostructure layer has the better response for LPG.
Effect of Introducing Free Gaseous Radicals of Trichlorosilane and Ammonia Precursors on Growth and Characteristics of LPCVD a-SiNx Ultra Thin Films
Authors: Salmasi Armin , Alamdari Eskandar Keshavarz
Published: November 2013

Preparation and characteristics of amorphous silicon nitride (a-SiNx) thin films deposited by low pressure chemical vapor deposition (LPCVD) are investigated. Free gaseous radicals of trichlorosilane (TCS) and ammonia (NH3) are produced by passing each of the precursor gases separately over Pt-Ir/Al2O3 catalyst at the temperature of 600 C. Kinetics studies of the LPCVD are carried out in different total pressures, NH3/TCS flow rate ratios and temperatures. Surface topography, chemical concentrations, growth rate and thickness are studied by Ellipsometry, x-ray photo-electron spectroscopy (XPS), atomic force microscopy (AFM) and auger depth profiling (ADP). Analysis of experiments indicates that at the temperatures between 730 C and 830 C, the growth rate of thin films follows an Arrhenius behavior with activation energy of 166.3 KJ.mol-1. The measured hydrogen contamination in a-SiNx ultra thin films is 1.05 at% which is 17 times lower than the corresponding contamination in the films produced by (PECVD) and 3.4 times lower than the contamination in the LPCVD thin films with silane (SiH4) or dichlorosilane (DCS) and Ammonia. The surface topography of the prepared films is smooth and uniform and the thickness varies between 23 and 101 nanometers.
Direct Growth of ZnO Nanorods on Zinc Substrate via Hydrothermal Method
Authors: Abdolhosseinzadeh Sina , Asgharzadeh Hamed
Published: November 2013

ZnO nanorods were grown on zinc substrate via hydrothermal method. Zn foils were immersed in an alkali solution and then heated in a Teflon-lined autoclave. The effects of alkali solutions pH (8-12), temperature (90-180 °C) and time (4-18 h) as well as seeding the substrate on the morphology and density of the ZnO nanorods have been investigated. The morphology and microstructure of the synthesized products were characterized by XRD, SEM and EDX. Nanorods with 100-800 nm in diameter and up to 3 μm in length were synthesized depending on the processing condition. It was found that at severe processing conditions, i.e. high OH- concentration, high temperature and prolonged time the nanorods tended to dissolve or disappear. Seeding the substrate leads to the formation of dense and highly-aligned nanorods.
Challenges Regarding to Usage of Nanostructured Materials in Contemporary Building Construction
Authors: Mahdavinejad Mohammadjavad , Rafsanjani Leili Hashemi , Rasoolzadeh Maryam , Nazari Marzieh
Published: November 2013

Development of ultrafine grained and nanostructured materials helps other disciplines and has made a meaningful contribution to other fields especially materials and building construction. New nanostructured materials open new horizons to scientific bases of building and construction materials. Sustecture - sustainable high-tech architecture is to meet new life architectural prerequisites regarding latest achievements in material engineering and new materials developments especially smart and nanostructured materials. Despite this fact, usage of new composite materials in building construction industry had yet to be widespread. Therefore the most important question which is remained to be answered is: what are the most challenges regarding to usage of nanostructured materials in contemporary building construction? Logical argumentation has been adopted as research method of this paper to answer research question, which finalized by descriptive - analytical techniques and depth diagnostic interviews. Samples have been selected randomly among from three major groups namely: 1-accademic scholars, 2-architectural consultants and 3-construction practitioners. The research is to find out the level of their awareness about new developed nanomaterials. In order to find out what are the most challenging issues which prohibited sustecture in achievement of its goals and objectives? The results of the paper show that level of technical knowledge and public awareness regarding to developments of new materials is not in a satisfactory condition especially in building construction and architectural performance side. In other word, however general knowledge regarding to ultrafine grained and nanostructured materials enhanced among architectural contributors, there is not enough technical knowledge among construction practitioners.
Preparation of Shaped Carbon Nanotube Composites with Porous Structures
Authors: Tabrizi Nooshin Salman , Yavari Maryam
Published: November 2013

Porous structures of carbon nanotube (CNT) composites with highly accessible surface areas have numerous potential applications such as heterogeneous catalysts and adsorbents. In this study sodium alginate was added to CNTs dispersions as gelling agent. Before being dried, the hydrogels were shaped into bead, disk, and sheet forms. The alginate in the composites was then decomposed by heating up the samples under an inert gas. The morphology of the as-prepared composite was studied by scanning and transmission electron microscopy and the pore size distribution was measured by BJH method. The MWCNT composite showed a density of around 0.08 g/cm3 and a specific surface area of 164 m2/g. The as-synthesized porous composite was examined as an adsorbent to remove methylene blue (MB) from aqueous solutions. Complete removal of MB was observed. The adsorption isotherm and kinetics were also evaluated.
Increasing the Performance of Machinery Tools by Super Hard Nanostructured Materials Reinforced with Nanoporous Aluminium Oxide
Authors: Rezaei Hojatolah , Omidvar Hamid , Pooladi Reza
Published: November 2013

The use of nanostructured thin films to improve physical and mechanical properties of cutting tools have been recently achieved wonderful progress in industrial and research centres. In this present work, anodic aluminium oxide (AAO) film is formed on the cutting tool by anodizing a thin film of aluminium foil. Aluminium coating is performed using an innovative electroplating method. Then the nanometric pores which are formed by the anodizing are filled with the resistant AlTiN using physical vapour deposition (PVD) method. This procedure results in a nanostructure with an aluminium oxide resistant texture which attains a high hardness and Young modulus. In this project we succeeded in designing aluminium oxide nanostructured as scaffolds for aluminium titanium nitride. Along with nanostructured alloy AlTiN, a unique hardness and wear resistance is obtained. This coating texture improvements the efficiency and tool life much better than other coating methods done, and as a result, a greater efficiency in production and reduction in costs is achieved.
Effect of SiC Nanoparticles Content and Milling Time on the Characteristics of Al/SiC Nanocomposite Powders Produced via Mechanical Milling
Authors: Akhlaghi Farshad , Mosleh-Shirazi Sareh
Published: November 2013

In the present study high energy ball milling was utilized to produce aluminum (Al-6061) matrix nanocomposite powders reinforced with nanosilicon carbide (SiC) particles. The starting materials containing different percentages (1,3 or 5 wt.%) of nanoSiC particles (25-50 nm) and Al (38-63 μm) were co-milled for different times (16, 20, 24 h) to achieve nanocomposite powders. The crystal size of powders were evaluated by quantitative XRD analysis. Laser particle size analysis was used to evaluate the size of powders during milling. The microstructure of powders and their microhardness values were evaluated by Scanning Electron Microscopy (SEM) and a microhardness tester respectively. The results indicated that the crystal size of the matrix alloy decreased by milling time. The increased SiC content up to 3% resulted in increased microhardness of the powders. However, further increase of SiC to 5% resulted in decreased microhardness due to agglomeration. It was concluded that the maximum microhardness together with a uniform distribution of SiC particles within the matrix alloy was obtained after 20 h milling of powder mixture containing 3% of SiC nanoparticles.
Characterization of Ni-CNTs Nanocomposites Produced by Mechanical Alloying
Authors: Gharegozloo Shaghayegh , Abdizadeh Hossein , Ataie Abolghasem
Published: November 2013

The interest in using CNTs as the reinforcement of metal matrix nanocomposites has been growing considerably due to their enhanced properties. In the present work, nickel was reinforced by carbon nanotubes (CNTs) via high energy mechanical milling method. The effects of various amounts of CNTs (5%, 10%, 20% and 30%) and different milling times (1, 5, 10 and 15 hours) were investigated. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and vibrating sample magnetometer (VSM) analysis were used for evaluation of phase composition, morphology and magnetic properties of the samples, respectively. The results showed a homogeneous dispersion of CNTs into the nickel matrix phase by mechanical milling. It was observed that the increase in the milling time, for a particular amount of CNTs, caused a decrease of mean crystallite size from 56 nm to 35 nm. The increase of CNTs amount also resulted in the powder particle refinement. VSM analysis showed that with the increase of CNTs from 0% to 30%, the magnetization of the samples decreases from 52.36 to 30.74 emu/g, and the coercivity of the nanocomposites increases from 61.45 to 114 Oe.
Microstructure and Mechanical Properties of Titanium Matrix Composite Reinforced by Functionalized MultiWalled Carbon Nanotube
Authors: Ghorbani Hassan , Habibolahzadeh Ali , Azadeh Mohammad , Kariminejad Arash
Published: November 2013

In this study, titanium matrix composites (TMCs) reinforced by functionalized multiwalled carbon nanotubes (MWCNTs) , prepared via powder metallurgy (PM) route. The powder mixture was pressed under 310 MPa (cold press), then sintered in vacuum furnace for 2h at 1300 °C . The Optimum mixing time under Ar atmosphere was 2h at mixing speed of 250 rpm. The microstructure of solid-state sintered composite was investigated by scanning electron microscopy and X-ray diffraction analysis. Mechanical properties of TMC were significantly improved by addition of functionalized MWCNTs compared to the pure titanium sample, due to uniform distribution of Un-bundled MWCNTs. in during mechanical alloying process, mixture powder reached ultrafine size.
Hydrogen Desorption Properties of Mechanically Alloyed MgH2-9 wt % V-1 wt% Al Nanocomposite
Authors: Gholipour Alireza , Rajabi Mohamad , Hoseinipour Seyed Jamal
Published: November 2013

In this study, 9 wt% V and 1 wt% Al were co-milled with MgH2 at different milling times to produce nanostructured composite powders. The effect of milling time and additives on the hydrogen desorption properties of obtained powders was evaluated by thermal analyzer method and compared with pure MgH2. The phase constituents and grain size of powders were characterized by X-ray diffractometry method. As the milling time was increased, both the grain size and hydrogen desorption temperature were decreased. An improved dehydrogenation temperature was achieved by alloying of MgH2 with V and Al. The effect of the V and Al addition on improvement of the dehydrogenation properties was discussed.
Ethanol Sensing Properties of Tin Oxide Doped Using Silver Nanoparticles
Authors: Rahimi Esmaeil , Sheikhi Mohammad Hossein , Horastani Zahra Karami , Sayedi S. Masoud , Zeinali Sedigheh , Zarifkar Abbas
Published: November 2013

Composite powders of SnO2 with different amounts of Ag nanoparticles (0.3 wt%, 0.5 wt%, 0.8 wt% and 1.5 wt%) were prepared by reducing an aqueous silver nitrate solution with NaBH4 followed by washing and heating treatments. Gas sensors, based on both pure SnO2 and the prepared composite powders were fabricated by simple, reproducible and low cost method of powder pressing followed by sintering in air at 500oC for 2 hours. The morphology of the materials was characterized by XRD and SEM methods. The gas sensing performance of all sensors were examined in an ethanol vapor atmosphere. Both pure SnO2 and Ag/ SnO2 based sensors showed high responses to the ethanol vapor. However, in terms of response time and working temperature the Ag/SnO2 based sensors showed better performances, i.e. they worked at lower temperatures and responded at shorter times. The response time of all sensors was less than 6s; however, optimized performance was observed for the sensor with 1.5% Ag concentration, showing 99% responses at 260oC with a response time of 3s. The results showed that Ag nanoparticles doped in SnO2, effectively can increase sensor performance for ethanol detection.
Deposition of Polyaniline/Silica Nanocomposite Coating on Stainless Steel; Study of its Corrosion Properties
Authors: Amirdehi Mohamad Fatahi , Afzali Darush
Published: November 2013

In the present century many efforts have been done to develop efficient methods for corrosion protection of steel in various industries. The use of conducting polymers is one of the new developments in the area. In this study, polyaniline/silica nanocomposite has been coated onto 316L stainless steel via in situ method. The corrosion behaviors of the bare and coated steels have been studied in order to reveal influence of silica nanoparticles (70nm).The prepared coating has been characterized using X-ray diffraction (XRD). The corrosion performance of the coating has been investigated in 1 M H2SO4 solution by using electrochemical impedance spectroscopy (EIS). It was found that protecting effect of coated layer is influenced by amounts of silica nanoparticles.
Transient Liquid Phase Bonding of Al/Mg2Si Composite Using a Cu-Ni Mixed Powder
Authors: Baghbani Milad Ghayoor , Hadian Ali Mohamad
Published: November 2013

Transient liquid phase bonding of Al/Mg2Si metal matrix composite (MMC) was investigated using a Cu-Ni mixed powder interlayer (1:1 proportion by weight) in an argon environment at various temperatures and holding time. The composite (MMC), containing 15% Mg2Si particles, was produced by in situ technique. The use of pure copper interlayer in Al/Mg2Si metal matrix composite causes reinforcement particles segregation at the bond interface. The region of weakness produced by the particles segregation at the bond region has been found to promote preferential failure during tensile testing. Using a mixture of Ni and Cu powder as filler material have shown less segregation of particles reinforcement along central bond zone. The composition and microstructure of the joined area were examined by X-ray diffraction (XRD) and scanning electron microscopy equipped with an energy dispersive X-ray spectroscopy (EDS). Shear tests were conducted to the samples to evaluate the effect of bonding duration on weldabillity. As the bonding time increases, with continual diffusion, the structural heterogeneity is diminished, and the microporosities are eliminated at the central bond zone. The shear strength of joints increased with increasing bonding duration.
Silver Nanocolloid: Synthesis, Optical and Thermo-Optical Properties
Authors: Hashemizadeh Sakineh , Rashidi Huyeh Majid
Published: November 2013

Linked to Surface Plasmon Resonance (SPR) phenomena, optical and thermo-optical properties of metal-dielectric nanocomposite materials including noble metal nanoparticles dispersed in a dielectric host medium are worthily interested. Indeed these materials have been proposed for many applications such as photonics devices, bio sensors and even photo-thermal therapy. Colloidal silver nanoparticles were synthesized by reduction of silver nitrate using of ascorbic acid and citrate as stabilizer agent in a 30°C water bath. The transmission electron microscopy (TEM) micrograph image shows formation of spheroidal silver nanoparticles with an average of large and small diameters about 43 and 34 nm respectively. Extinction spectrum, measured using UV-Vis spectroscopy, represented two peaks located around 420 and 620 nm of wavelength. These peaks are attributed to SPR phenomena and confirm spheroidal and spherical silver nanoparticle formation in solution. Thermo-optical properties of synthesized silver nanocolloids are then evaluated by measuring of extinction spectrum at different temperatures. Results showed an enhancement in thermo-optical properties of silver nanocolloids around the SPR wavelengths. Theoretical analysis, done using Mie and Mie-Gans theories, showed that the different peaks observed in extinction spectrum are related directly to shape effect.
Determination of Tryptophan Using Nanocomposite-Based Sensor
Authors: Islamnezhad Akbar , Jobaneh Esmaeil Farzaneh
Published: November 2013

In this study, the nanoComposite Silica Perchloric Acid Poly (2-Methyl Aniline) (NSPPMA) was synthesized under the solvent-free condition and used as modifier in preparation of chemically modified electrode (CME). The effect of the composition of carbon paste electrode on its voltammograms were evaluated in basic solution with 5.0 × 105 M Trp. It was found that addition of NSPPMA to the carbon paste would generate the peak current of Trp because of its catalytic effect on redox process. The best analytical response was obtained at pH 12.0. The anodic peak currents were proportional to Trp concentrations in the range of 2.5 × 109 5.0 × 10-4 M under the optimized experimental conditions. The detection limit was 1.7 × 10-10 M. The correlation of the peak currents against v1/2 (v is the scan rate) is linear. The proposed method was applied to the determination of Trp in pharmaceuticals formulations successfully.
Characterization of Nano-Structured Multiferroic Bismuth Ferrite Produced via Solid State Reaction Route
Authors: Mostafavi Ebrahim , Ataie Abolghasem , Ahmadzadeh Mostafa
Published: November 2013

Multiferroic bismuth ferrite, BiFeO3, was synthesized via conventional solid-state reaction method using Bi2O3, Fe2O3 as starting materials. Effects of Bi2O3/Fe2O3 molar ratio and calcination temperature on the phase composition, morphology and magnetic properties of produced powders were systematically studied using XRD, FESEM/EDS and VSM techniques, respectively. The results revealed that BiFeO3 phase with rhombohedral R3c structure with a mean particle size of 40 nm was formed in the sample processed with a Bi2O3/Fe2O3 molar ratio of 1:1 after calcination at 800 °C. Rietveld analysis which was applied to the x-ray diffraction data via MAUD software indicated high purity of 95%wt for the above sample. Deviation from the stoichiometric molar ratio (Bi2O3/Fe2O3: 0.9, 1.1, 1.2) yielded higher content of the intermediate phases of Bi2Fe4O9 and Bi25FeO40. FESEM studies showed that the mean particle size was increased from 40 to 62 nm by increasing calcination temperature from 800 to 850 °C. VSM results for 1:1 molar ratio samples indicated that increasing the calcination temperature from 800 to 850 °C increased saturation magnetization (Ms) from 0.087 to 0.116 emu/g and also coercive field (Hc) from 60 to 100 Oe.
Improvement and Red Shift Toward Visible Spectrum of TiO2 Nanofibers through Doping by Fe2O3 and Nitrogen
Authors: Salehifar Nahideh , Nikfarjam Alireza
Published: November 2013

TiO2has many applications as photocatalyst, photo/electrochromic device, solar cell and sensors. It has been activated only by UV light. In this research we have been investigated on the effect of adding Fe2O3nanoparticles and N on the absorption spectrum in order to increase their activity and shift toward visible light for TiO2nanofibers. We used electrospining method to fabricate nanofibers. Sol gel for spinning pure nanofibers contains Titanium tetraisopropoxide (C12H28O4Ti), acetic acid (CH3COOH), ethanol (C2H5OH) and PVP (C6H9NO-12 wt.% ). Then we used Fe2O3nanoparticle (size: 2040 nm, purity: 98%) and HNO3acid for doping. Among Fe2O3-doped samples, the 2.1 wt% Fe2O3indicated the highest activity for visible light, while with HNO3, excellent photo-catalyst activity obtained at 1.5wt% Fe2O3and 5 wt% HNO3(purity :65%). The final solutions were stacked into the syringe and joined to a high voltage DC supply. A piece of glass stacked on aluminum foilwas used as collector. Finally nanofibers calcined at 500°C. FESEM, XRD and Spectrophotometry techniques were employed to deliberation nanofibers. Diameter of the fibers was approximately 100 nm (anatase: 77%). The Fe2O3-TiO2and Fe2O3-N-TiO2nanofibers indicated respectively 50% and 80% growth in absorption intensities under visible light irradiation compared to pure nanofiber and absorption spectrum peak moved towards larger wavelengths (70 and 100nm) when TiO2doped with Fe2O3and Fe2O3-N. Keywords:Fe2O3nanoparticle; nitrogen; red shift; TiO2nanofiber; UV-visible irradiation.
Influence of Deposition Voltage on Growth of ZnO Nanowires by Cathodic Electrodeposition
Authors: Akbari Elahe , Ayati Nooshin , Marashi Seyed Pirooz
Published: November 2013

Zinc oxide nanowires (NWs) were synthesized by potentio-static cathodic electrodepsition in polycarbonate (PC) template at 70 °C. The electro-reduction of hydroxide ions in presence of Zn2+ ions within Zn (NO3)2 is involved in the growth of nanowire arrays. Altering various deposition parameters such as deposition voltage made it possible to obtain arrays of vertically aligned ZnO NWs with different growth rates. Furthermore, the effect of voltage on the chronoamperometric diagrams was studied. The X-ray diffraction pattern clearly confirms the polycrystalline nature of the ZnO NWs; however, Scanning Electron Microscopy (SEM) images reveal that the length of NWs slightly increases by increasing deposition voltage. It is demonstrated that varying deposition voltage has a significant impact on the growth rate but a small changes of the size of NWs is observed.
One-Step Synthesis of CoFe2O4 Nano-Particles by Mechanical Alloying
Authors: Rashidi Sedigheh , Ataie Abolghasem
Published: November 2013

In this study, cobalt ferrite (CoFe2O4) nanoparticles were synthesized by intensive mechanical alloying of CoCO3 and α-Fe2O3 powder using a planetary high energy ball mill in air without any subsequent heat treatment. Effects of milling time on the phase composition, morphology and magnetic properties of the powders were evaluated using XRD, FESEM and VSM techniques, respectively. XRD results indicated that single phase CoFe2O4 nanoparticles with a mean crystallite size of 15 nm were synthesized after 25 hours of mechanical milling. FESEM images confirmed the formation of uniform nanoparticles and showed that the mean particle size of the milling products was decreased from 51 to 25 nm by increasing the milling time from 20 to 30 hours. VSM measurements of the sample milled for 25 hours revealed a saturation magnetization (Ms) of 52.19 emu/g and coercivity (Hc) of 831.95 Oe, which were higher than those of 20 hours milled sample.
Template Assisted Growth of Zinc Oxide-Based Nanowires and Piezoelectric Properties
Authors: Ayati Nooshin Sadat , Akbari Elahe , Marashi Seyed Pirooz , Saramad Shahyar
Published: November 2013

In this paper, we report on the synthesis of ZnO nanowires via templated electrochemical deposition. ZnO nanowire arrays were fabricated by potentiostatic electrodeposition in track-etched polycarbonate (PC) membrane. The electrolyte was aqueous solution containing zinc nitrate precursor. The electrodeposition process involves the electroreduction of nitrate ions to alter the local pH and precipitation of the metal oxide within the pores. The morphology analysis and structure characterization of the ZnO nanowires were carried out using conventional scanning electron microscopy (SEM) and X-Ray diffraction. To check the piezoelectric characteristics of the zinc oxide nanowires, the AFM microscope is used in contact mode. The scanned area was 5µm*5µm and the affected force was 30nN. In result of scanning each nanowire with conductive AFM tip in contact mode, a current peak which had a width smaller than topography peak was fabricated. This is due to semi-conductivity and piezoelectricity characteristics of Nanowires.
The Effect of Quenching Rate on Structure and Soft Magnetic Properties of High Bs Fe-Based Nanocrystalline Alloys
Authors: Hosseini-Nasb Farzad , Beitollahi Ali , Moravvej-Farshi Mohammad Kazem
Published: November 2013

Recently some nanocrystalline soft magnetic materials containing nanosized α-Fe grains have been obtained by crystallization of amorphous melt-spun ribbons. These structures are nanocomposites in which nanosized grains are distributed within an amorphous matrix. The soft magnetic ribbons composed of Fe80B10Si8Nb1Cu1 alloy were prepared by melt spinning method with different quenching rates (wheel speed of 10, 20 and 40 m/s). The XRD results exhibit an increase in the copper wheel speed (quenching rate) causes the fraction of crystallinity and grain size to decrease. The grain size varies in the range of 20 to 200 nm that is in good agreement with TEM results. The VSM results show that these nanostructured samples exhibit coercivity in the range of 10 to 30 A/m and magnetic saturation in the range of 1.5 to 1.7 T.
Molecular Dynamics Simulation of Nanocluster Formation in a Supersonic Nano Nozzle Fabricated by Anodizing the Aluminum
Authors: Tanhai Mohammad Hossein , Saramad Shahyar , Nayebi Peyman
Published: November 2013

A molecular dynamics method has been developed and applied for simulation of a supersonic Ne gas expansion through a convergingdiverging nozzle. Although the classical nucleation theory is able to explain some physics of the nucleation processes, however, due to the physical inaccuracy of the classical nucleation theory for small clusters, molecular dynamic method is more usable for studying gas flows having clusters. Pressure, flow velocity, temperature were parameters that extracted by MD method along the central x-axis. The nucleation and condensation of the clusters and their transient and equilibrium behavior are other parameters that are investigated in this simulation. The results show that although with suitable conditions the formation of clusters in a nanonozzle is possible, but the size of clusters is much smaller than its counterpart in macro scale and clusters with especial magic numbers are formed. The proposed novel method for fabrication this kind of nanonozzle is multi-step anodizing of the aluminum. This nanonozzle which can be fabricated experimentally can be used in Ionized Cluster Beam Deposition (ICBD) method.
Modification of Nanoclay Systems: An Approach to Stabilizing Drilling Fluids
Authors: Kafashi Sahar , Taghdimi Ramin , Karimi Gholamreza
Published: November 2013

This study was aimed to investigate the rheological properties and the possibility of nano(Na, Ca )- bentonites nanoproducts to meet the required drilling mud properties. Sepiolite (Sp) and the mixture of 2% nanoNaB with 1% Sp were collected and prepared from Irans oil Company (NIOC). The nanoclay performance evaluation involved the experimental tests of the rheological properties, filtration and gel strength. According to the results obtained from flow properties tests for the mixture, it was indicated that the mixture was not adequate to be a suitable drilling fluid. The main objective was to make stable dispersions with nanobentonite and sepiolite by using a water soluble polymer as stabilizer. The changes in the rheological properties of bentonite were investigated at various concentrations of polyvinyl alcohol (PVA) to discover the stability of the dispersions. The standard API tests were applied for drilling fluid to determine the properties of dispersions.
Preconcentration and Determination of Lead by Solidification of Floated Organic Drop Coupled with Nanodrop Spectrophotometry
Authors: Mazloomifar Ali , Khatibi Nafiseh
Published: November 2013

The liquid-phase microextraction based on solidification of floating organic microdrop coupled with UV-visible spectrophotometer for preconcentration and determination of lead in the aqueous samples has been developed. In this technique, 20μL of 1-undecanol containing dithizone as the chelating agent (10-3mol L-1) was transferred to the water samples containing lead ions, and the solution was stirred for 25 min. The sample vial was cooled in an ice bath for 5 min. The solidified extract was transferred into a conical vial where it melted immediately, and then the organic phase was analyzed by Nanodrop spectrophotometer. Factors that influence the extraction and complex formation, such as pH, concentration of dithizone, extraction time, effect of ionic strenght, temperature and stirring rate were optimized. Under the optimized conditions, a preconcentration factor of 356, detection limit of 0.006 μgL-1, limit of quantification 0.018 μgL-1and a good relative standard deviation of 2.1% were obtained. The procedure was applied to sea water, mineral water and well water.
Optical Properties of Synthesized Fe3O4 Nanoparticles Doped in Nematic Liquid Crystal under Electric Field
Authors: Dehghani Zahra , Iranizad Esmaiel Saievar , Alamouti Abbas Faraji , Nadafan Marzieh
Published: November 2013

The average particle size of synthesized nanoparticles (nps) was found to be about 34 nm as analyzed using scanning electron microscopy (SEM). The nonlinear optics measurements were performed by using z-scan method with 532 nm wavelength CW Nd:YAG laser. The influence of electric field on the nonlinear optical responses for nematic liquid crystals (NLCs) doped with nps was considered in different voltages. The measurements were performed with ferronematics for two commonly initial alignments (homogeneous and homeotropic) with small compositional percentage of magnetic nps (i.e. 1% W/W). The experimental results show that the magnitudes of nonlinearity in homeotropic alignment samples are larger than homogeneous ones. Results show that the applied electric field had a great effect on the nonlinear optical properties of NLCs doped with nps in homogeneous alignment samples and do not have any significant affect in homeotropic alignment samples.
Mitigation of Fine Particles Migration in Deep Bed Filters Treated by a Nanofluid Slug: An Experimental Study
Authors: Arab Danial , Pourafshary Peyman , Ayatollahi Shahaboddin
Published: November 2013

Fine particles migration in porous media (deep bed filters) is one of the main reasons causing formation damage especially during any well stimulation techniques or enhanced oil recovery (EOR) processes. It has been explained by lifting of in-situ fine particles present in the medium, their motion with the flow, and finally their capture at some pore throats. Attachment of particles to the rock surface during EOR agent injection into the reservoir can be a very promising remedy for the aforementioned challenge. In this experimental study, the role of nanoparticles-treated medium as an adsorbent of suspended particles has been investigated. Different concentrations of MgO and SiO2 nanoparticles were utilized to treat the synthetic porous media. In several core flooding tests, a stable suspension was injected into the already nanoparticles-treated medium and particles concentration of effluents was measured by turbidity analysis. In order to quantify the effect of nanoparticles to alter the medium surface characteristics, zeta potential analysis and dynamic light scattering methods have been applied. The results indicated that the presence of nanoparticles on the medium surface alters the zeta potential of the rock which in turn, results in critically reduction of particles concentration in the effluent samples compared with the non-treated media. It was found that treating with 0.03 wt% of MgO nanoparticles is the best scenario among the tests performed in this study. This finding was confirmed by DLVO theory by which the total energy of interactions existing between a particle and the rock surface was calculated.
Sol-Gel Synthesized Nanostructured Silica Particles for Application in Gas Transport Properties of PU-PDMS Based Mixed-Matrix Membranes
Authors: Semsarzadeh Mohammad Ali , Vakili Eshagh , Fardi Milad , Ghalei Behnam
Published: November 2013

New Silicon based nanostructures particles were successfully synthesized by tetraethoxysilane (TEOS) as silica precursor, mixture of two copolymers of PPG-b-PPE-b-PPG and PEO-b-PPG-b-PEO (Plutonic) as templates. PU-PDMS and PU-PDMS/silica composite membranes were prepared by solution casting technique. Synthesized mesoporus silica particles and hybrid membranes were characterized using Nitrogen adsorption-desorption (BET), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). As confirmed by BET analysis, the mean pore diameters of SPB1,2 Silicon particles are around 9 nm. The SEM micrographs confirmed the nanoscale distribution of silica particles in the polymer matrix. Gas permeation of PU-PDMS/silica hybrid membranes with silica contents of 5, 10 and 20 wt.% was studied for N2, CO2 and He single gases at8 bar. The obtained results suggest a significant increase in permeability of all gases upon increasing the silica particles content. The possible reasons for such behavior were stated and discussed.
Application of Nano Silica in Concrete for Enhanced Resistance against Sulfate Attack
Authors: Moslemi Amir Mahdi , Khosravi Arash , Izadinia Mohsen , Heydari Mohaddeseh
Published: November 2013

Durability of concrete structure is a critical issue especially in severe environment when the concrete structure is exposed to sulfate attack, such as shorelines. nanoSilica is high pozzolanic material which is used recently in concrete to improve its mechanical properties. However, the durability of concrete against sulfate attack containing nanoSilica (NS) has not been investigated completely. In this study, the effects of NS has been studied on compressive strength, sulfate attack and morphology characteristics. The results show that increasing of compressive strength in specimens with NS is significant in early ages. Resistance of concrete specimen against sulfate attack was measured in 5% sodium sulfate solution for expansion of prime specimens. After a period of 180 days the samples containing zero, 2, 4, 6 and 8% NS lost 3.51%, 2.4%, 2.23%, 1.13% and 1% of their weights compared to the initial weights, respectively. The results indicate that the concrete samples containing 8% NS show best performance in terms of resistance against sulfate attack.
Commercialization Strategies for Industrial Applications of Nanomaterials in Building Construction
Authors: Mahdavinejad Mohammadjavad , Nazari Marzieh , Khazforoosh Sina
Published: November 2013

Ultrafine grained, nanostructured materials and other types of recombinant nanomaterials open new windows for future technology which make a revolutionary progress in key technologies such as chemistry, material sciences etc. Literature review of the paper shows that nanomaterials have a lot to do with building construction however there is not an influential relationship between usage of nanostructured materials and building industry. In the other word, commercialization and industrial applications of recombinant nanomaterials had yet to find its own role in contemporary architecture and the building construction industry. Therefore the most important question of the research is: what are the most important commercialization strategies regarding to industrial usage of nanomaterials in building construction? The results of the paper show that there is not a meaningful coherence between scientific researches and professional requirements. Moreover academic disciplines generally focus on theoretical era rather than professional fields. In order to make a more prosperous researches regarding to recombinant nanomaterials; should focus on 1-energy, 2-light, 3-security and 4-intelligence; as the most important commercialization strategies regarding to industrial usage of nanomaterials in building construction. Through these four determining strategies, nanomaterials may be adopted in coatings, panels and insulation in building construction; especially in partial requirements like roofs and facades, interior and exterior spaces.
Production of Ultrafine Grained API X70 Steel with Controlled Rolling
Authors: Abdideh Reza , Hizombor Mohammad , Rad Reza Mohammadian , Zadeh Iman Mohammad
Published: November 2013

Development of industries in recent years reveals the essential need to the microalloyed steels with high strength and good ductility. Refinement of Ferrite grains by thermomechanical Treatment is the only lower cost effective method to improve strength and toughness spontaneously in this type of steels. API X70 steel belongs to high strength microalloyed steel group. The manufacturing process of this steel is controlled rolling which is a kind of thermomechanical treatment and it is considered as a grain refining method. In this research, three specimens of API X70 steel were experimentally rolled in order to achieve ultrafine grained microstructure. Rolling operations are designed in such a way that the rolling of these specimens finished at 846, 823 and 800°C. Results of the experiments were analyzed by mechanical tests and microstructures observations. The microstructure observations show that decreasing of finish rolling temperature causes decrease in Ferrite grain size. Results also show that rolling of API X70 steel in the vicinity of Ar3temperature and high strain rates lead to ultrafine Ferrite grains in microstructure. This is due to the transformation of work hardened austenite to Ferrite. On the other side, Tensile and impact tests show that decreasing of finish rolling temperature causes increasing in yield and tensile strength and also improves the toughness.
Synthesis and Antifungal Property of Mg Doped Zinc Oxide Nanocubes on the Glass Substrate Using Solution-Evaporation Method at Low Temperature
Authors: Esmaili Mohammad Javad , Ayubzadeh Mohsen , Zakeri Zahra , Eskandari Mehdi
Published: November 2013

This in this paper, we report the synthesis of Mg doped ZnO nanocubes on the glass substrate by using solution-evaporation method at low temperature for the first time. Samples are characterized by means of scanning electron microscopy (SEM) and X-ray diffraction (XRD). The samples have a pure phase and no characteristic peaks are observed for the other impurities, such as Mg and MgO. It was observed that the length and width of the ZnO nanocubes are about 100nm and morphology of the samples is cube-shape. A blue-shift is observed in the band-edge with introduction of Mg into zinc oxide structure. The anti-fungal results indicate that ZnO nanocubes arrays exhibit stable properties after two months and play an important role in growth inhibitory of Candida albicans.
Synthesis of GaN Nanoparticles by DC Plasma Enhanced Chemical Vapor Deposition
Authors: Gholampour Mahdi , Abdollah-Zadeh Amir , Poursalehi Reza , Shekari Leila
Published: November 2013

The unique optical properties of nanostructured GaN basically, turn it as a very important part of many electronic and optoelectronic devices such as high power transistors, UV detectors, solar cells, lasers and blue LED. The aim of the current study is GaN nanoparticle deposition at low temperature in preferred direction. In this work, GaN nanoparticles were prepared using direct current plasma enhanced chemical vapor deposition (DC-PECVD) method on Si (100) wafer as a substrate at 700°C. Gallium metal and nitrogen plasma were used as precursors. GaN nanoparticles were grown based on the direct reaction between gallium atoms and excited nitrogen species in the plasma. Structural and morphological characterizations of GaN nanoparticles were carried out using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS) and field emissions electron microscopy (FE-SEM). Preferred (100) direction of GaN nanostructures which obtained by careful control of processing parameters, were revealed by XRD. FE-SEM images show the average diameter of nanoparticles is 37 nm. The EDS results show the Ga to N ratio in the sample was 8.8 to 1.2 by weight which is very close to the Ga to N ratio of prefect GaN crystal. The deviance is related to the nitrogen vacancy of the sample. These results demonstrate a simple inexpensive method for GaN nanoparticle deposition at low temperature which is critical for many of applications.
Localized Electrochemical Corrosion Characteristics of Carbon Steel in Seawater
Authors: Zou Yan , Bai Qiang , Wang Jia , Wang Wei , Kong Xiang Feng
Published: November 2013

The galvanic and potential distributions of carbon steel immersed in seawater were studied by wire beam electrode (WBE) technique. Results indicated that the corrosion of carbon steel in seawater tended to local corrosion. With immersion time increasing, local corrosion was more and more serious. During the initial immersion period, the top of the coupon near the water surface was main cathode. With the corrosion extended, corrosion products gradually gathered on the surface of the carbon steel. Potential differences between cathode and anode gradually became small. Cathode and anode redistributed on the surface of carbon steel. At last, the top and the bottom were cathode while the middle was anode. The areas of anode first increased and then decreased. The areas of cathode were in contrast.