Search for: surface-area
Total 178 records
Optimization of particle size and specific surface area of pellet feed in dry ball mill using central composite design, Article Indian Journal of Science and Technology ; Volume 9, Issue 44 , 2016 ; 09746846 (ISSN) ; Halali, M ; Sharif University of Technology
Indian Society for Education and Environment 2016
Objective: The dimensional properties of iron ore pellet feed including specific surface area and particle size distribution in the ball mill was studied using response surface area method. Methods/Statistical analysis: The effect of the operational parameters of dry ball mill including ball charge (20-40%), grinding time (30-50 min) and balling distribution (Small, Mixed and Large) on dimensional properties of pellet feed was meticulously examined and optimized using response surface methodology based on Central Composite Design (CCD). Responses were 80% passing size (D80) and Blaine (BL). A total of 30 grinding experiments were designed and carried out in the CCD method. Regression models...
M.Sc. Thesis Sharif University of Technology ; Movaghar Rahimabadi, Ali
The plausibility of embedding cycles of different lengths in the graphs of a network (known as the pancyclicity property) has important applications in Interconnection networks, parallel processing systems, and implementation of a number of either computational or graph problems such as those used for finding storage schemes of logical data structures, layout of circuits in VLSI and etc. OTIS network is an important Interconnection network that worth investigating. This kind of network has benefits of having electronic connection and optic connection simultaneously. Furthermore, independent of the technology of network, the topology of this network has importance. In this thesis, we have...
Article Geotechnical Special Publication ; February , 2014 , p. 553-562 ; Khosravi, M ; Sadaghiani, M. H ; Meehan, C. L ; Amini, E ; Sharif University of Technology
This paper presents results from a series of constant normal load direct shear tests on artificially created rock joints, in an attempt to quantify the effects of different factors that contribute to the shear strength along "ideal" rock joints. Particular focus is given to the effect of asperity orientation with respect to the direction of shearing. In many historical rock joint shear strength criteria, the effect of a joint's roughness on the joint shear strength is described based on analysis of only a single profile in the direction of shearing. More recent studies have observed that the distribution of sheared area on a joint surface during shear is significantly affected by the...
Mechanical and microstructural properties of cement paste incorporating nano silica particles with various specific surface areas, Article Key Engineering Materials, 8 July 2010 through 9 July 2010 ; Volume 478 , July , 2011 , Pages 19-24 ; 10139826 (ISSN) ; 9783037851357 (ISBN) ; Vayghan, A. G ; Bolhasani, M ; Sharif University of Technology
In this study, the effect of agglomeration and non-uniform dispersion of silica particles on the mechanical and microstructural properties of cement paste incorporating silica fume and nanosilica (NS) with various specific surface areas (SSA) is experimentally investigated. The SSA and replacement percent of silica particles were considered as test variables and four series of mixes were made including one set of mixes for silica fume with a SSA of 20 m2/g and three sets of mixes for three different types of NS with SSA equal to 90, 200 and 380 m2/g. In each series of mix designs three different cement replacement percents of 1.5%, 3% and 5% were applied. The results indicate that as the SSA...
Article Journal of Applied Physics ; Volume 119, Issue 1 , 2016 ; 00218979 (ISSN) ; Shasti, M ; Ramezani Sani, S ; Mortezaali, A ; Sharif University of Technology
American Institute of Physics Inc
Titanium oxide (TiO2)-based photodetectors were fabricated using a thermal oxidation technique. The effect of two different annealing temperatures on morphology, structure, and I-V characteristics has been investigated. TiO2/Si heterostructure exhibited diode-like rectifying I-V behavior both in dark and under illumination. Dependence in photoresponse on annealing temperature was observed that was related to effective surface area of quasi-one-dimensional TiO2 nanostructures. Fabricated TiO2/Si diodes in 850 °C as the lower annealing temperature showed higher responsivity and sensitivity compared with grown ones in 950 °C (R850 °C/R950 °C ∼ 5 and S850 °C/S950 °C ∼ 1.6). Rather good...
Article Journal of Energy Chemistry ; Volume 26, Issue 4 , 2017 , Pages 762-767 ; 20954956 (ISSN) ; Moosavifard, S. E ; Shahraki, M ; Elyasi, S ; Sharif University of Technology
In recent years, development of high-performance supercapacitor electrode materials has stimulated a great deal of scientific research. The electrochemical performance of a supercapacitor strongly depends on its material structures. Herein, we report a simple strategy for high-performance supercapacitors by building pseudocapacitive CuS nanospheres with nanoporous structures, nanosized walls (<10 nm) and relatively large specific surface area of 65 m2/g. This electrode demonstrates excellent electrochemical performance including a maximum specific capacitance of 814 F/g at 1 A/g, significant rate capability of 42% capacitance retention at an ultrafast rate of 50 A/g, and outstanding...
Article Discrete Mathematics ; Volume 309, Issue 3 , 2009 , Pages 560-569 ; 0012365X (ISSN) ; Sarbazi Azad, H ; Akl, S. G ; Sharif University of Technology
The star graph, as an interesting network topology, has been extensively studied in the past. In this paper, we address some of the combinatorial properties of the star graph. In particular, we consider the problem of calculating the surface area and volume of the star graph, and thus answering an open problem previously posed in the literature. The surface area of a sphere with radius i in a graph is the number of nodes in the graph whose distance from a given node is exactly i. The volume of a sphere with radius i in a graph is the number of nodes within distance i from the given node. In this paper, we derive explicit expressions to calculate the surface area and volume in the star graph....
Article Acta Materialia ; Volume 55, Issue 13 , 2007 , Pages 4455-4466 ; 13596454 (ISSN) ; Fray, D. J ; Sharif University of Technology
Nanostructured and mesoporous TiO2-Ga2O3 thin films with various Ti:Ga atomic ratios were prepared by a new straightforward particulate sol-gel route. Titanium isopropoxide and gallium (III) nitrate hydrate were used as precursors, and hydroxypropyl cellulose (HPC) was used as a polymeric fugitive agent (PFA) in order to increase the specific surface area (SSA). XRD and TEM analysis of the powders revealed that the Ga2O3 formed from the nitrate precursor retarded anatase-to-rutile transformation, crystallization and crystal growth. The average crystallite size of pure TiO2 powder annealed at 600-1000 °C were in the range 4-10 nm; the values that could be decreased to 2-6 nm for TiO2-Ga2O3...
Synthesis of high surface area nanocrystalline anatase-TiO2 powders derived from particulate sol-gel route by tailoring processing parameters, Article Journal of Sol-Gel Science and Technology ; Volume 40, Issue 1 , 2006 , Pages 15-23 ; 09280707 (ISSN) ; Cordero Cabrera, M. C ; Ghorbani, M ; Fray, D.J ; Sharif University of Technology
Stabilised titania sols were prepared using an additive free particulate sol-gel route, via electrostatic stabilisation mechanism, with various processing parameters. Peptisation temperature, 50°C and 70°C, and TiO2 concentration, 0.1, 0.2 and 0.4 molar, were chosen as processing parameters during sol preparation. Results from TiO2 particle size and zeta potential of sols revealed that the smallest titania hydrodynamic diameter (13 nm) and the highest zeta potential (47.7 mV) were obtained for the sol produced at the lower peptisation temperature of 50°C and lower TiO 2 concentration of 0.1 M. On the other hand, between the sols prepared at 70°C, smaller titania particles (20 nm) and higher...
Preparation of high surface area titania (TiO2) films and powders using particulate sol-gel route aided by polymeric fugitive agents, Article Sensors and Actuators, B: Chemical ; Volume 120, Issue 1 , 2006 , Pages 86-95 ; 09254005 (ISSN) ; Cordero Cabrera, M. C ; Fray, D. J ; Ghorbani, M ; Sharif University of Technology
High specific surface area (SSA) nanocrystalline powders and dip-coated TiO2 films have been prepared by particulate sol-gel route aided with polymeric fugitive agents (PFA), namely trehalose dihydrate (THD), polyethylene glycol (PEG6000) and hydroxypropyl cellulose (HPC). Powders obtained without PFA, heat-treated at 160 °C show a SSA of 181 m2/g, a value that could be increased up to 271 and 223 m2/g for samples heat-treated at 300 °C when PEG6000 and HPC were used, respectively, whereas SSA of 201 m2/g were achieved by using THD and subsequence heat-treating at 500 °C. Such surface area is one of the highest reported in the literature under these conditions. Crystallite sizes vary from 1...
On the rate of oxidation of co on La2O3 doped NiO/Al2O3 catalysts: An artificial neural network approach, Article Reaction Kinetics and Catalysis Letters ; Volume 85, Issue 2 , 2005 , Pages 347-353 ; 01331736 (ISSN) ; Gobal, F ; Sharif University of Technology
The rate constants of the oxidation of CO on a number of pure and La 2O3 doped NiO/Al2O3 solid catalysts were correlated with the mole percent of dopant, calcinations temperature, surface area, pore volume and pore mouth diameter by an artificial neural network simulator. The cross validation method had to be used due to the scarcity of the data. A three-layer network with 3 nodes in the hidden layer was found to simulate the system well. © Akadémiai Kiadó, Budapest. All rights reserved
Article Journal of Materials Chemistry ; Volume 21, Issue 26 , May , 2011 , Pages 9634-9640 ; 09599428 (ISSN) ; Azimirad, R ; Safa, S ; Hasani, E ; Sharif University of Technology
Various morphologies of CuO/Cu(OH)2 nanostructures with different adsorbed -OH contents were synthesized on an acid-treated Cu foil through variation of NaOH concentration from 0 to 50 mM with an in situ oxidation method. X-ray diffractometry and X-ray photoelectron spectroscopy (XPS) indicated formation of CuO on the Cu(OH)2 crystalline phase at a growth temperature of 60°C for 20 h. Antibacterial activity of the nanostructures against Escherichia coli bacteria was studied in the dark and under light irradiation. The nanostructures grown at a NaOH concentration of 30 mM showed the highest surface area and the strongest antibacterial activity among the samples. After elimination of the...
Article Scientia Iranica ; Volume 18, Issue 3 C , June , 2011 , Pages 479-485 ; 10263098 (ISSN) ; Kazemeini, M ; Rashidi, A. M ; Jozani, Kh. J ; Sharif University of Technology
Highly active unsupported MoO3 and Co -MoO3 catalysts were prepared by a simple solution reaction method in the presence of different organic additives. Catalysts were characterized by the XRD, BET surface area measurement, SEM and TEM techniques. Results suggested that utilizing different additives produced different morphologies OfMoO3 microstructures. Optimizing reaction conditions was found to produce more active molybdenum oxide nanoparticles when urea and PEG200 additives were utilized. XRD and TEM results indicated crystal growth restriction after cobalt incorporation. Catalytic activities of prepared materials were evaluated in the hydrodesulfurization reaction of Naphtha. Products...
Enhancement of biological nitrogen removal performance using novel carriers based on the recycling of waste materials, Article Water Research ; Volume 170 , March , 2020 ; Borghei, S. M ; Raie, M ; Sharif University of Technology
Elsevier Ltd 2020
This study aims to enhance biological nitrogen removal performance by the innovative carbon-based carriers. The new carriers were produced based on recycling waste materials. In these carriers, the advantages of the hybrid system and physicochemical properties of activated carbon were integrated to promote microbial attachment. To verify the performance of the new carriers compared to the conventional moving carriers, the experiments were conducted in two parallel laboratory-scale sequencing batch reactors under various operating conditions. The analysis revealed that the specific surface area of the new carrier with a total pore volume of 0.0015cm3/gr was 10.9 times the specific surface...
Fabrication and evaluation of controlled release of doxorubicin loaded UiO-66-NH2 metal organic frameworks, Article International Journal of Engineering, Transactions B: Applications ; Volume 34, Issue 8 , 2021 , Pages 1874-1881 ; 1728144X (ISSN) ; Hassanzadeh Nemati, N ; Ramezani Saadatabadi, A ; Sadrnezhaad, S. K ; Sharif University of Technology
Materials and Energy Research Center 2021
The metal-organic frameworks (MOFs) due to their large specific surface area and high biocompatibility are suitable as carriers for drug delivery systems (DDSs). In the present study, doxorubicin (DOX) as an anticancer drug was loaded into UiO-66-NH2 MOFs to decrease the adverse side effects of pristine DOX use and to increase its efficiency through the controlled release of DOX from MOFs. The MOFs were synthesized via microwave heating method and characterized using X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett- Teller analysis. The drug loading efficiency, drug release profiles from synthesized MOFs and pharmacokinetic studies were investigated. The biocompatibility...
Design, Fabrication and Testing of Novel Coils Aimed at Increasing the Free Surface Area of Levitated Samples in Electromagnetic Levitation Melting, M.Sc. Thesis Sharif University of Technology ; Halali, Mohammad
Condensation from a gaseous phase is a common method for the fabrication of metallic nanoparticles. Electromagnetic induction furnaces are the most common equipment used for this method. Since the sample doesn’t touch any foreign object, this method is one of very few ways to synthesize ultrapure nanoparticles. However, a major setback of this method is its low production rate.One of the only workarounds to this issue is to increase the melt’s surface area so as to present a larger surface for evaporation. In the common setup for this furnace the molten sample takes on a spherical shape which unfortunately holds the lowest surface to volume ration of any shape. The endeavor in this study has...
Article Journal of Solid State Electrochemistry ; Vol. 19, Issue. 1 , 2014 , pp. 269-274 ; ISSN: 1432-8488 ; Zad, A. I ; Shahrokhian, S ; Sharif University of Technology
Here, a solvothermal method for synthesis of porous Ni–Co binary oxide (NiCo2O4) nanorods followed by thermal decomposition is described. The prepared nanorods were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Brunauer Emmett Teller (BET) methods. These porous NiCo2O4 nanostructures were promising candidates in the development of high capacity supercapacitors and having excellent cycling performance due to high specific surface area. In addition, the influence of annealing rate on the structure and electrochemical behavior of the synthesized nanorods was investigated. The results showed that the annealing rate had a direct effect on the crystalline...
Development and biomedical application of nanocomposites: In situ fabrication of ZnO-PbO nanocomposite through microwave method, Article Materials Technology ; Vol. 29, issue. 4 , July , 2014 , p. 227-231 ; Aieneravaie, M ; Dorosti, V ; Sadrnezhaad, S. K ; Sharif University of Technology
A novel nanocomposite of ZnO-PbO with flower-like nanostructure was fabricated from zinc acetate and lead nitrate as principle raw materials via an in situ process. The novelty of this study consists in the use of a common approach for fabricating of ZnO and PbO nanoparticles simultaneously. From these experiments the conclusion might be drawn that Zn(NH4) 2 4+ ions and Pb(OH)2 act as precursors for the nucleation and growth of ZnO and PbO respectively under microwave irradiation. The precursors formation were carried at two stages: reaction between zinc ions and lead nitrate with ammonium ion and hydroxide sodium respectively. The average crystalline size of Zno and PbO has been analysed by...
Investigating the effect of calcination repetitions on the lifetime of Co/γ-Al2O3 catalysts in Fischer-Tropsch synthesis utilising the precursor's solution affinities, Article Journal of the Taiwan Institute of Chemical Engineers ; Volume 44, Issue 2 , 2013 , Pages 205-213 ; 18761070 (ISSN) ; Kazemeini, M ; Khorasheh, F ; Zarkesh, J ; Sharif University of Technology
Cobalt-based catalysts were prepared on different alumina supports, and their behaviour for different Fischer-Tropsch synthesis (FTS) conditions assessed. Although Co/γ-Al2O3 is a well-known FTS catalyst, its durability ought to be improved to make the industrial process economically feasible. Here calcination repetitions effects on the catalyst lifetime were examined utilising reactor tests and characterisation techniques including XRD, TPR, ICP and N2 porosimetry. Results revealed that fewer calcination repetitions improved catalyst activity and selectivity. Based upon the XRD results, these findings appeared to be due to the improved size of cobalt crystals on the pore surfaces. These...
Article Proceedings of IEEE Sensors ; 2011 , Pages 5-7 ; 9781424492886 (ISBN) ; Roghayeh, G ; IEEE SENSORS Council ; Sharif University of Technology
In this article we report hydrogen sensing property of WO 3/MWNTs thin films that were fabricated by spin-coating on alumina substrates. The MWNTs were initially functionalized (f-MWNTs) to enhance dispersion in the sol of multiwalled carbon nanotubes (MWNTs) and tungsten trioxide (WO 3). Microstructure, morphology and chemical composition of the materials were characterized by SEM, TEM, XRD and XPS methods. Our results show WO 3 nanoparticles were nucleated on oxygenated group on surface of f-MWNTs in hybrid suspension. After annealing the films at 350 °C, electrical conductance measurements at different operating temperature were performed and the results indicates rather fast and linear...