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Molecular dynamics simulation of manipulation of metallic nanoclusters on double-layer substrates [electronic resource]
, Article Physica E: Low-dimensional Systems and Nanostructures ; 2010, Vol. 42, No. 9, pp. 2364-2374 ; Meghdari, Ali ; Jalili, Nader ; Amiri, Farshid ; Sharif University of Technology
Abstract
Molecular dynamics simulations are carried out to investigate the manipulation of metallic clusters on double-layer surfaces. The system parts are made of transition metals. The conditions which are subjected to change in the tests are material combinations for cluster, main substrate and lubricant layer (adlayer). In addition to qualitative observations, two criteria which represent the particle deformation and substrate abrasion are utilized as evaluation tools and are computed for each case. Obtaining this sort of knowledge is highly beneficial for further experiments in order to be able to plan the conditions and routines, which guarantee better success in the manipulation process
Microwave absorption characteristic of a double-layer X-band absorber based on MWCNTs/La0.6Sr0.4Mn0.5Fe0.5O4 coated with PEDOT polymer
, Article Ceramics International ; Volume 47, Issue 12 , 2021 , Pages 17736-17744 ; 02728842 (ISSN) ; Dang, X ; Boudaghi, R ; Akhtar, M. N ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In this study, a novel double-layer microwave absorber was designed based on the MWCNTs/La0.6Sr0.4Mn0.5Fe0.5O4 (C/LSMFO) and PEDOT-coated (P@[C/LSMFO]) nanocomposites. Co-precipitation and in-situ polymerization methods were utilized to synthesize the C/LSMFO and P@[C/LSMFO] nanocomposites, respectively. XRD, FESEM, VSM, and VNA analysis were used to determine the structural, morphological, magnetic, and electromagnetic properties of the nanocomposites. Single-layer absorbers with thicknesses of 1, 1.5, and 2 mm were fabricated, and electromagnetic parameters were evaluated via VNA in the X-band frequency. Moreover, the microwave absorbing features of the double-layer absorber with various...
Molecular dynamics simulation of manipulation of metallic nanoclusters on double-layer substrates
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 42, Issue 9 , 2010 , Pages 2364-2374 ; 13869477 (ISSN) ; Meghdari, A ; Jalili, N ; Amiri, F ; Sharif University of Technology
2010
Abstract
Molecular dynamics simulations are carried out to investigate the manipulation of metallic clusters on double-layer surfaces. The system parts are made of transition metals. The conditions which are subjected to change in the tests are material combinations for cluster, main substrate and lubricant layer (adlayer). In addition to qualitative observations, two criteria which represent the particle deformation and substrate abrasion are utilized as evaluation tools and are computed for each case. Obtaining this sort of knowledge is highly beneficial for further experiments in order to be able to plan the conditions and routines, which guarantee better success in the manipulation process
Dye-sensitized solar cells based on TiO2 particulate gels: Impact of gel formation mechanism on photovoltaic performance
, Article Journal of Photochemistry and Photobiology A: Chemistry ; Volume 338 , 2017 , Pages 104-114 ; 10106030 (ISSN) ; Mohammadi, M. R ; Sharif University of Technology
Elsevier B.V
2017
Abstract
In this work the influence of different particulate gels on morphology and photoelectric performance of TiO2 dye-sensitized solar cells (DSCs) is studied. Two coagulant and flocculant agents are used to convert a TiO2 particulate sol into the gels using double layer compression and charge neutralization mechanisms. One more TiO2 particulate gel is also prepared by changing the pH of the sol using acid: alkoxide molar ratio higher than the critical ratio to obtain an unstable sol. Based on X-ray diffraction (XRD) analysis, the films contain primary nanoparticles with average crystallite size of 13–15 nm. Field emission scanning electron microscopy (FE-SEM) images show uniform, nanostructured...
An atomistic insight into interfacial properties of brine nanofilm confined between calcite substrate and hydrocarbon layer
, Article Applied Surface Science ; Volume 490 , 2019 , Pages 89-101 ; 01694332 (ISSN) ; Badizad, M. H ; Ayatollahi, S ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Molecular dynamics simulation was applied in this study to scrutinize the interfacial properties of water nano-film confined between calcite mineral and hydrocarbon layer, as two intrinsically different media. Such system resembles the environment experienced by water molecules in the pore spaces of underground carbonate reservoirs. The interplay between water film and confining phases, oil and mineral, strongly influences hydrocarbon production process; however, there is a lack of detailed understanding of the involved interactions. MD simulations indicate development of several layers with different water densities in the confined brine. Water molecules form well-ordered structure in three...
Development of high-efficient double layer microwave absorber based on Fe3O4/carbon fiber and Fe3O4/rGO
, Article Journal of Magnetism and Magnetic Materials ; Volume 537 , 2021 ; 03048853 (ISSN) ; Niaz Akhtar, M ; Boudaghi, R ; Sharif University of Technology
Elsevier B.V
2021
Abstract
Recently, preparation of lightweight absorbers with high performance capability are urgently needed for practical demanded in order to solve the severe electromagnetic pollution. In the present study, two different composites (Fe3O4/carbon fiber and Fe3O4/rGO) were uniformly incorporated into resin epoxy matrix to obtain single and double layer X-band absorber with 20 wt% filler loading. Each of the composites were prepared via solvothermal process. According to the results, the minimum reflection loss values for each single layer Fe3O4/carbon fiber and Fe3O4/rGO absorber were −15 dB (3 mm thickness and 1.5 GHz bandwidth) and −50 dB (3 mm thickness and 4 GHz bandwidth) respectively. By...
How do ions contribute to brine-hydrophobic hydrocarbon Interfaces? An in silico study
, Article Journal of colloid and interface science ; Volume 575 , 2020 , Pages 337-346 ; Koleini, M. M ; Hartkamp, R ; Ayatollahi, S ; Ghazanfari, M. H ; Sharif University of Technology
NLM (Medline)
2020
Abstract
HYPOTHESIS: The saltwater-oil interface is of broad implication in geochemistry and petroleum disciplines. To date, the main focus has been on the surface contribution of polar, heavy compounds of crude oil, widely neglecting the role of non-polar hydrocarbons. However, non-polar compounds are expected to contribute to characteristics of oil-brine interfaces. METHODOLOGY: Utilizing molecular dynamics simulation, we aim to characterize ion behavior adjacent to hydrophobic organic phases. Concerning natural environments, NaCl, CaCl2 and Na2SO4 electrolytes at low (5 wt%) and high (15 wt%) concentrations were brought in contact with heptane and/or toluene which account for aliphatic and...
A practical review study on shaped charge in the last two decades (2000–2020)
, Article International Journal of Protective Structures ; Volume 12, Issue 4 , 2021 , Pages 665-693 ; 20414196 (ISSN) ; Ramezani, A ; Nabakhteh, M. A ; Liaghat, G ; Sharif University of Technology
SAGE Publications Inc
2021
Abstract
Shaped charges are devices used for cutting or penetrating different aerial, on land, and underwater targets, based on the concentration of the explosion energy to the liner. The purpose of this study is to present a practical review of the studies related to shaped charges in the last twenty years (2000–2020). In this regard, these studies have been reviewed in two different categories for ordinary and advanced shaped charges. In the case of ordinary shaped charges, different aspects including shaped charges against different targets, different types of shaped charges (such as linear shaped charge and explosively formed penetrators), and theoretical advancements are presented. On the other...
Improved efficiency of dye-sensitized solar cells aided by corn-like TiO2 nanowires as the light scattering layer
, Article Electrochimica Acta ; Volume 90 , 2013 , Pages 302-308 ; 00134686 (ISSN) ; Mohammadi, M. R ; Dadar, H ; Fray, D. J ; Sharif University of Technology
2013
Abstract
We present a new TiO2 morphology, featuring highly crystalline anatase structure, synthesized by a two consecutive hydrothermal operation for the manufacture of dye-sensitized solar cells (DSSCs). This construct is a one-dimensional (1D) nanostructure (i.e., nanowire) with interconnected nanoparticles on the surface with a large percentage of reactive facets, so called corn-like nanowire. Such morphology is produced by a surface modification concept using surface tension stress mechanism. The double layer DSSC made of anatase-TiO2 nanoparticles as the under-layer and corn-like TiO 2 nanowires as the over-layer (as light scattering layer) shows higher conversion efficiency of 7.11% and short...
Wettability Altration Determination by Using Streaming Potential
, M.Sc. Thesis Sharif University of Technology ; Massihi, Mohsen (Supervisor) ; Ayatollahi, Shahabodin (Supervisor)
Abstract
The assessment of fluid transport in porous media is the main subject in oil reservoirs to understand the oil recovery efficiency. The efficiency of Enhanced oil recovery (EOR) processes depends on the surface properties and wetting behavior of oil reservoir rocks which are also affected by the electrokinetic behavior of solid part of the porous rock. Streaming potential measurement is one of the techniques to determine the electrokinetic properties. The streaming potential measurements using electrodes have recently been introduced in oil field applications and there are still significant uncertainties during the measurements and interpretation of streaming potential results. The Primarily...
Transport Phenomena in Electrokinetically Generated Microflows
, Ph.D. Dissertation Sharif University of Technology ; Saeedi, Mohammad Hassan (Supervisor) ; Mozaffari, Ali Asghar (Supervisor) ; Chakraborty, Suman (Co-Advisor)
Abstract
This is a theoretical study on heat and mass transfer in electrokinetically driven microfluidic devices with particular consideration to the lab-on-a-chip (LOC) applications. Special attention is given to disclose the effects of the fluid rheology and the aspect ratio of the rectangular geometry on the surface reaction kinetics and the temperature rise due to the Joule heating. Along this line, two different viscoelastic constitutive equations namely PTT and FENE-P models along with the power-law viscosity model are being considered. The secondary aims also include exploring the influences of the fluid properties variations throughout the channel cross section on the hydrodynamic and thermal...
On the pseudocapacitive behavior of nanostructured molybdenum oxide
, Article Journal of Solid State Electrochemistry ; Volume 14, Issue 4 , 2010 , Pages 643-650 ; 14328488 (ISSN) ; Gobal, F ; Raissi, H ; Moghiminia, S ; Sharif University of Technology
Abstract
Nanostructured molybdenum oxide was potentiodynamically deposited onto a stainless steel surface from an aqueous bath by cycling the potential between 0 and -0.75 V vs. Ag/AgCl. The deposit consisted of particulates in the range of 30 to 80 nm. Electrochemical studies under galvanostatic charge/discharge and also impedance spectroscopy revealed capacitive behavior in the potential range of -0.3 to -0.55 V vs. Ag/AgCl with the value of 477 F g-1 at 0.1 mA/cm2. An equivalent circuit comprising of three parallel branches consisting of double-layer capacitance, Warburg impedance, and a constant phase element signifying pseudo-capacitance each coupled with their corresponding resistances was...
Electroosmotic flow and ionic conductance in a pH-regulated rectangular nanochannel
, Article Physics of Fluids ; Volume 29, Issue 6 , 2017 ; 10706631 (ISSN) ; Saidi, M. H ; Sadeghi, A ; Sharif University of Technology
Abstract
Infinite series solutions are obtained for electrical potential, electroosmotic velocity, ionic conductance, and surface physicochemical properties of long pH-regulated rectangular nanochannels of low surface potential utilizing the double finite Fourier transform method. Closed form expressions are also obtained for channels of large height to width ratio for which the depthwise variations vanish. Neglecting the Stern layer impact, the effects of EDL (Electric Double Layer) overlap, multiple ionic species, and association/dissociation reactions on the surface are all taken into account. Moreover, finite-element-based numerical simulations are conducted to account for the end effects as well...
Wettability alteration modeling for oil-wet calcite/silica nanoparticle system using surface forces analysis: contribution of DLVO versus non-DLVO interactions
, Article Industrial and Engineering Chemistry Research ; Volume 57, Issue 43 , 2018 , Pages 14482-14492 ; 08885885 (ISSN) ; Ghazanfari, M. H ; Kazemeini, M ; Jamialahmadi, M ; Helalizadeh, A ; Sharif University of Technology
American Chemical Society
2018
Abstract
In this work, application of silica nanoparticles for wettability alteration of initially oil-wet calcite was investigated through analysis of surface forces and DLVO theory. Doing so, the wettability and zeta potential of calcite surfaces were measured through the sessile drop method and an in-house experimental setup, respectively. Primary evaluation indicated that incorporating DLVO terms in the Frumkin-Derjaguin model was not sufficient to describe the wettability in an oil-wet calcite/nanofluid system. Sensitivity analysis showed that calculating the double-layer interaction using constant potential-constant potential boundaries along with structural hydrophobic forces (non-DLVO...
Sandblasting improves the performance of electrodes of miniature electrical impedance tomography via double layer capacitance
, Article Heliyon ; Volume 6, Issue 4 , 2020 ; Mohammadpour, R ; Gatabi, J. R ; Mirhoseini, M ; Ahmadi, M ; Sasanpour, P ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Effect of sandblasting of the copper electrode structures before deposition of gold thin film for micro electrical impedance tomography (EIT) system has been studied experimentally. The comparison has been performed on the unmodified copper electrodes and the sandblasted electrodes before deposition of gold layer, using structural analysis while their performance in EIT system has been measured and analyzed. The results of scanning electron microscopy and atomic force microscopy show that the sandblasting of the electrodes results in the deposition of gold film with smaller grain size and uniformly, comparing to the unmodified structure. The measurement of impedance shows that the...
A new multi level clustering model to increase lifetime in wireless sensor networks
, Article 2nd International Conference on Sensor Technologies and Applications, SENSORCOMM 2008, Cap Esterel, 25 August 2008 through 31 August 2008 ; 2008 , Pages 185-190 ; 9780769533308 (ISBN) ; Jahangir, A. M ; Taghikhani, Z ; Azarderakhsh, R ; IARIA ; Sharif University of Technology
IEEE Computer Society
2008
Abstract
Most of clustered models in wireless sensor networks use a double-layered structure. In these structures a node is considered as cluster-head and has the responsibility of gathering information of environment. Static attribute is the main disadvantage of these clustering method. because as traffic rises in environment as time passes, cluster-head nodes energy and its close nodes, is consumed rapidly and so these nodes that has important role in data gathering, are break down. This issue is considered as age decrease in network life time and finally, network death. In this paper, a new three-layered dynamic model is introduced that its main goal is to increase network life time. The dynamic...
SnO2/ZnO double layer thin films: A novel economical preparation and investigation of sensitivity and stability of double layer gas sensors
, Article International Journal of Nanomanufacturing ; Volume 2, Issue 1-2 , 2008 , Pages 59-69 ; 17469392 (ISSN) ; Shokuhfar, A ; Sadrnezhaad, S. K ; Shokuhfar, T ; Sharif University of Technology
Inderscience Publishers
2008
Abstract
A double-layer SnO2/ZnO gas sensor was produced by utilisation of SnOSUB align=right2 and ZnO thin films. Top layer consisted of SnOSUB align=right2 produced by a sol gel-controlled annealing technique. Bottom coating consisted of ZnO thin film precipitated by Two-Stage Chemical Deposition (TSCD) from an aqueous zinc-containing solution. Both top and bottom coatings were analysed by SEM, XRD, EDAX and AAS. Gas sensitivity of the SnO2/ZnO double layer was determined by electrical resistance measurements. Although sensitivity was slightly reduced by double-layer formation, selectivity and stability were considerably improved by combination of the two thin layers. The existence of an...
Theoretical analysis of the performance of a model supercapacitor consisting of metal oxide nano-particles
, Article Journal of Solid State Electrochemistry ; Volume 11, Issue 8 , 2007 , Pages 1085-1092 ; 14328488 (ISSN) ; Gobal, F ; Sharif University of Technology
2007
Abstract
The factors influencing the electrochemical behaviour of a supercapacitor have been partly examined in this work. The effects of so-called intrinsic parameters, i.e. exchange current density, unit cell length and double layer (DL) capacitance; as well as the so-called application parameters, i.e. cell current, on the cell potential discharge time have been considered. The contributions of each type of capacitors, DL capacitor and faradaic supercapacitor under various states of operation and material have been analyzed, and the competing (compensating) effects of the two types of capacitors as regards to the discharge and power characteristics manifested by current-potential and energy-power...
Cluster/polarized continuum models for density functional theory investigations of benzimidazole corrosion inhibitors at metal/solution interface
, Article Corrosion ; Volume 62, Issue 3 , 2006 , Pages 199-206 ; 00109312 (ISSN) ; Arshadi, M. R ; Parsafar, Gh. A ; Sastri, U. S ; Sharif University of Technology
National Assoc. of Corrosion Engineers International
2006
Abstract
The molecular behavior of some benzimidazole (C7H 6N2) derivatives as corrosion inhibitors ojiron in hydrochloric acid (HCl) solution was investigated quantum electrochemically via the inhibitors' chemical potential (μ), molecular softness (σ), and the extent of charge transfer from the inhibitor to the metal (ΔN). These quantities were obtained from density functional theory (DFT) calculations for three models, i.e., isolated inhibitors (in vacua), inhibitors in solution, and, finally, inhibitors in electrical double layer (EDL). In these models, the effects of solvent, substrate, and electric field were considered using a polarized continuum model, iron Fe13(9,4) cluster, and a...
Calcium chloride adsorption at liquid-liquid interfaces: A molecular dynamics simulation study
, Article Colloids and Surfaces A: Physicochemical and Engineering Aspects ; Volume 527 , 2017 , Pages 70-80 ; 09277757 (ISSN) ; Bahramian, A ; Chen, P ; Pourafshary, P ; Goddard, W.A., III ; Ejtehadi, M. R ; Sharif University of Technology
Abstract
We carried out molecular dynamics simulations (MD) to investigate the adsorption of calcium chloride (CaCl2) at n-hexane-water interfaces. We also measured the interfacial tensions (IFT) of the selected systems making use of the pendant-drop method. The histograms of hexane, water, and the ions indicate an electrical double layer (EDL) near the interface. The trend of the EDL indicates that chloride anions intend to adsorb to the interface more intrinsically than calcium cations. The measured interfacial width of the n-hexane-water interfaces decreases with the salt concentration. The average densities of the interfacial and bulk aqueous solutions demonstrate density heterogeneity in the...