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Experimental study of the ventilation arrangement’s effect on particle concentration in a surgery room
, Article 7th International Conference on Fluid Flow, Heat and Mass Transfer, FFHMT 2020, 15 November 2020 through 17 November 2020 ; 2020 , Pages 151-1-151-4 ; Mousemi, A ; Alotaibi, S. A ; Khademi, A ; Sharif University of Technology
Avestia Publishing
2020
Abstract
Hospital ventilation is defined as the providing of fresh and clean air stream in hospital wards or patients’ room to provide and establish a healthy environment for personnel’s and patient’s breath, reducing concentration of produced contaminations in hospital and removing them from clean spaces. Thus, it can prevent spread of airborne infections among patients, people who works around and more importantly, outside the hospital. Hospital infections have a huge influence on mortality of the patients in which respiratory tract infections and surgical wound infections plays a major role. Depending on the quality and the mass flow rate of the exploited air, cleanness of a surgery room can be...
A microfluidic concentration gradient generator for simultaneous delivery of two reagents on a millimeter-sized sample
, Article Journal of Flow Chemistry ; Volume 10, Issue 4 , 2020 , Pages 615-625 ; Saidi, M. S ; Kashaninejad, N ; Sharif University of Technology
Springer International Publishing
2020
Abstract
Microfluidic concentration gradient generators (μCGGs) are indispensable parts of many emerging lab-on-a-chip platforms for biological studies and drug delivery applications. Most of the μCGGs reported in the literature can only generate the desired concentration gradients in a micron-sized sample (e.g., cells). As such, there is an unmet need to design a μCGG that can generate continuous concentration gradients of multi reagents (e.g., drugs) in a millimeter-sized sample (e.g., tissue). Herein, we report the proof-of-concept of this class of μCGG by combining a modified tree-like CGG with a micromixer. By conducting both experimental investigation and numerical analysis, we show that the...
Prediction of critical micelle concentration of some anionic and cationic surfactants using an artificial neural network
, Article Asian Journal of Chemistry ; Volume 19, Issue 4 , 2007 , Pages 2479-2489 ; 09707077 (ISSN) ; Konuze, E ; Jalali Heravi, M ; Sharif University of Technology
2007
Abstract
The critical micelle concentration (CMC) of a set of 58 alkylsulfates, alkylsulfonates, alkyltrimethyl ammonium and alkylpyridinium salts were predicted using an artificial neural network (ANN). The multiple linear regression (MLR) technique was used to select the important descriptors that act as inputs for artificial neural network. These descriptors are Balaban index, heat of formation, maximum distance between the atoms in the molecule, Randic index and volume of the molecule. Designed artificial neural network is a fully connected back-propagation network that has a 5-5-1 architecture. The results obtained using neural network were compared with those obtained using MLR technique....
Determination of optimal conditions for pressure oxidative leaching of sarcheshmeh molybdenite concentrate using Taguchi method
, Article Journal of Mining and Metallurgy, Section B: Metallurgy ; Volume 48, Issue 1 , 2012 , Pages 89-99 ; 14505339 (ISSN) ; Yoozbashizadeh, H ; Sharif University of Technology
2012
Abstract
The present research work is based on finding the optimum conditions for pressure oxidative leaching of the molybdenite concentrate to produce technical-grade molybdic oxide (MoO 3) with high recovery through further treatment of the filtrate solution. The Taguchi method was used to design and minimize the number of experiments. By using Taguchi orthogonal (L 25) array, five parameters (time, temperature, oxygen pressure, pulp density and acid concentration) at five levels were selected for 25 experiments. The experiments were designed and carried out in a high-pressure reactor in the presence of nitric acid as solvent and oxidizing agent for the molybdenite concentrate and its ReS 2...
Electrochemical charging of H in sour simulated environment in steel
, Article European Corrosion Congress 2011, EUROCORR 2011 ; Volume 4 , 2011 , Pages 2978-2988 ; 9781618394125 (ISBN) ; Dolati, A ; Bolzoni, F ; Lazzari, L ; Sharif University of Technology
2011
Abstract
The hydrogen diffusivity and subsurface concentration (C app) were evaluated by fitting a series expansion of the diffusion equation to the permeation data. The hydrogen diffusivity in the steel was found to be approximately in a order of magnitude 10 -7 cm 2 s -1. The influence of the passive layer on the hydrogen permeation and its influence on the evaluation of diffusion and trapping characteristics were discussed. Hydrogen diffusion experiments in A106 GRB carbon steel pipeline were performed electrochemically at 25°C in NACE B, solution in various amount of sulphide ion concentrations. In this case the effect of concentration of sulphide ion evaluated by study the electrochemical...
Study of electrochemical hydrogen permeation in iron
, Article Journal of Corrosion Science and Engineering ; Volume 14 , February , 2011 , 263–267 ; 14668858 (ISSN) ; Dolati, A ; Lazzari, L ; Bolzoni, F ; Sharif University of Technology
Abstract
Hydrogen diffusion experiments in A106GR B carbon steel pipeline were performed electrochemically at 25°C in NACE,B, solution in various amount of sulfide ion concentration for a thin sample. In this case the effect of concentration of sulfide ion evaluated by study the electrochemical behavior of sample by the galvanostatic way. Generally, sulfur components were found to increase the hydrogen permeation rate. Presence of sulfide layer helped to absorption of hydrogen reduction and exacerbates the amount of hydrogen absorption in steel. this phenomena can be noted that as regard to analysis of corrosion products which formed in the surface sample, the high amount of FeS, The sulfide ion are...
Preparation of mesh-reinforced cellulose acetate forward osmosis membrane with very low surface roughness
, Article Korean Journal of Chemical Engineering ; Volume 34, Issue 12 , 2017 , Pages 3170-3177 ; 02561115 (ISSN) ; Mousavi, S. A ; Ramazani Saadat Abadi, A ; Sadeghi, M ; Sharif University of Technology
Abstract
Mesh-reinforced cellulose acetate (CA)-based membranes were prepared for forward osmosis (FO) by immersion precipitation. Casting compositions such as CA percent and 1, 4-dioxane/acetone ratio and also preparation conditions such as evaporation time, coagulation bath and annealing temperatures were tested for membranes’ performance. The results were compared with commercially CTA membranes. The best membrane (17.9% polymer and 1, 4-dioxane/acetone ratio of 1.89) showed water flux of 9.3 L/m2h (LMH) and RSF of 0.536 mol NaCl/m2h. Moreover, the membrane structure was reinforced by a polyester mesh, which created micro pores in the back of the membrane. This caused higher water flux and RSF...
CFD simulation of bubble in flow field: Investigation of dynamic interfacial behaviour in presence of surfactant molecules
, Article Colloids and Interface Science Communications ; Volume 27 , 2018 , Pages 1-10 ; 22150382 (ISSN) ; Fayzi, P ; Lotfi, M ; Arzideh, S. M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
This work presents the results of numerical simulation of liquid flow on a static bubble. Velocity and surfactant concentration profiles of the liquid around a bubble exposed in flow field were estimated via unsteady CFD solution. Governing equations are the Navier-Stokes and conservation of mass in the liquid bulk and at the interface. Resulted profiles of surfactant concentration and velocity in the liquid bulk are used to determine the dynamic surface tension data via two adsorption isotherms of Langmuir and Frumkin. Data of dynamic surface tension were validated via experimental data of “bubble in flow field” protocol. Surface concentrations of surfactants were also numerically...
Optical concentration of gold nanoparticles as a new concept of analytical sensitivity
, Article Instrumentation Science and Technology ; 2020 ; Shokoufi, N ; Seyed Reihani, S. N ; Sharif University of Technology
Bellwether Publishing, Ltd
2020
Abstract
Concentration procedures have always been implemented when trace analysis of compounds in real matrices is contemplated. A variety of concentration strategies have been reported aiming at decreasing the limits of detection (LODs). The optical concentration of the substance in solution is one of the novel concepts for the enhancement of the analytical sensitivity. In this study, the optical concentration has been measured by the trapping of gold nanoparticles ((Formula presented.) nm) dispersed in water at low-concentrations at the focal volume of the laser beam. The influence of factors such as the time of gold nanoparticle trapping, the size of the nanoparticles, the intensity of the laser...
Biological treatment of petroleum contaminated soils by soil slurry-sequencing batch reactors (SS-SBRs)
, Article 4th International Conference on Waste Management and the Environment, Waste Management 2008, Granada, 2 June 2008 through 4 June 2008 ; Volume 109 , 2008 , Pages 751-758 ; 17433541 (ISSN); 9781845641139 (ISBN) ; Torabian, A ; Azimi, A. A ; Vossoughi, M ; Sharif University of Technology
WITPress
2008
Abstract
The soil slurry-sequencing bath reactor (SS-SBR) was studied to treat poorly graded sand with clay (SP-SC) contaminated by aged petroleum hydrocarbons and polycyclic aromatic hydrocarbons (PAHs) with concentrations of 23000 mg/kg and 750 mg/kg respectively. An 8 L bioreactor was operated with a 10% solid concentration (0.1 kg dry soil/L slurry). The fill period was relatively instantaneous, and the draw period lasted approximately 1 minute so the react period comprised essentially the entire cycle time. In the draw period a fraction of slurry (10%) was removed from the SS-SBR weekly and it was replaced with untreated slurry. This volumetric replacement strategy provided 70 days hydraulic...
Ferrofluidic open loop pulsating heat pipes: Efficient candidates for thermal management of electronics
, Article Experimental Heat Transfer ; Vol. 27, issue. 3 , Dec , 2014 , p. 296-312 ; ISSN: 08916152 ; Taslimifar, M ; Saidi, M. H ; Shafii, M. B ; Afshin, H ; Hannani, S. K ; Sharif University of Technology
Abstract
Thermal management of electronic devices is presently a serious concern. This article investigates the thermal performance of a five-turn open-loop pulsating heat pipe in both start-up and steady thermal conditions. The effects of working fluid, namely water and ferrofluid, heat input, charging ratio, ferrofluid concentration, orientation, as well as application of magnetic field, are explored. Experimental results show that using ferrofluid enhances the thermal performance in comparison with the case of distilled water under certain conditions. In addition, applying a magnetic field on the open-loop pulsating heat pipe charged with ferrofluid improves its thermal performance. Charging...
Strain and stress concentrations in elastomers at finite deformations: effects of strain-induced crystallization, filler reinforcement, and deformation rate
, Article Acta Mechanica ; Volume 227, Issue 7 , 2016 , Pages 1969-1982 ; 00015970 (ISSN) ; Reese, S ; Arghavani, J ; Naghdabadi, R ; Sharif University of Technology
Springer-Verlag Wien
Abstract
Strain and stress concentrations are studied for elastomers at finite deformations. Effects of strain-induced crystallization, filler reinforcement and deformation rate are also investigated, and micromechanical descriptions are provided for the observed results. A simple problem is subjected to finite element simulations to show the results evidently. Material parameters are obtained from experimental tests conducted on standard tensile samples of filled and unfilled natural rubber (NR) as well as styrene–butadiene rubber (SBR) as crystallizing and non-crystallizing rubbers, respectively. In all simulations, the strain concentration factor KE is shown to decrease monotonically where the...
Effect of an obstacle on the depositional behaviour of turbidity currents
, Article Journal of Hydraulic Research ; 2018 , Pages 1-15 ; 00221686 (ISSN) ; Yaghoubi, S ; Firoozabadi, B ; Afshin, H ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
Turbidity currents are responsible for much of the sedimentation in reservoirs. In order to control these flows, various methods such as placing an obstacle in their path have been proposed. In this study, the effect of inlet sediment concentration and obstacle height on the behaviour of turbidity currents is investigated experimentally. For this purpose, some experiments were carried out with different inlet concentrations and various obstacle heights. Velocity and concentration profiles were measured using an acoustic Doppler velocimeter. To examine the depositional behaviour of turbidity current, suspended sediment flux was calculated using velocity and concentration profiles of the...
A study of nanovoid, Griffith-Inglis crack, cohesive crack, and some associated interaction problems in fcc materials via the many body atomic scale FEM
, Article Computational Materials Science ; Volume 45, Issue 2 , 2009 , Pages 275-284 ; 09270256 (ISSN) ; Kamalzare, M ; Sharif University of Technology
2009
Abstract
Due to inadequacy of the classical continuum theories at the nano-scale when dealing with defects, stress concentrators, and relevant deformation phenomena in solids, a refined approach that can capture the discrete atomic features of solids is essential. The inability to detect the size effect, giving unrealistically high values for some components of the stress field right on the edge of the stress concentrators, and infirmity to address the complex interaction between small inhomogeneities, cracks and as such when they are only a few nanometers apart, are among some of the drawbacks of the classical approach. An atomistic study which employs atomic finite element method in conjunction...
A new non-dimensional parameter to obtain the minimum mixing length in tree-like concentration gradient generators
, Article Chemical Engineering Science ; Volume 195 , 2019 , Pages 120-126 ; 00092509 (ISSN) ; Saidi, M. S ; Kashaninejad, N ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
Microfluidic-based concentration gradient generators (CGGs) have a number of applications in chemical, biological and pharmaceutical studies. Thus, precise design of the microfluidic system is crucial to maintaining the desired concentration gradient in microchannels. One of the design considerations is the length of microchannels in the structure of a CGG. A CGG with a short length fails to provide the complete diffusive mixing, while the size of the microchip would unfavorably increase by incorporating a long CGG. Considering a CGG as a tree-like structure consisting of T-shaped micromixers, the mixing process of the species at a straight microchannel has been solved analytically. Herein,...
Investigation of precursors concentration in spray solution on the optoelectronic properties of CuInSe2 thin films deposited by spray pyrolysis method
, Article Journal of Materials Science: Materials in Electronics ; 2020 ; Ghorashi, S. M. B ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
Springer
2020
Abstract
Copper indium selenide CuInSe2(CISe) thin films were deposited by chemical spray pyrolysis (CSP) method of CuInS2(CIS) and subsequent selenization process. To study the effects of solution concentration, we prepared different precursors solution of CIS including different amount of indium salts from 0.025 to 0.100 M with In/Cu 1.25 and S/In 4. These results propose that solution concentration is critical for inflecting the morphological, optical, electrical, and electrochemical characteristics of solution-processed CISe films and device performance. The studied morphological properties of deposited samples were homogenous, crack-free with large grains in indium salt concentrations more than...
Influences of polymer-surfactant interaction on the drop formation process: an experimental study
, Article Langmuir ; Volume 37, Issue 3 , 2021 , Pages 1025-1036 ; 07437463 (ISSN) ; Salehi, M. S ; Firoozabadi, B ; Afshin, H ; Sharif University of Technology
American Chemical Society
2021
Abstract
The interaction between polymer and surfactant molecules affects the physical properties of liquids, which could be of great importance in an abundance of processes related to drop formation. Polymer and surfactant concentration is a factor that dramatically impacts the shape of molecular networks formed in the fluid bulk and the characteristics of a forming drop. In this study, the deformation and detachment of aqueous carboxymethyl cellulose (CMC) solutions' drops containing different concentrations of sodium dodecyl sulfate (SDS) are studied experimentally. Our purpose is to determine the effects of CMC and SDS concentrations on the parameters related to the formation process, including...
A new designed linear Fresnel lens solar concentrator based on spectral splitting for passive cooling of solar cells
, Article Energy Conversion and Management ; Volume 230 , 2021 ; 01968904 (ISSN) ; Saboohi, Y ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
The use of solar concentrators can be an alternative for initial cost reduction in the PV systems. However, they suffer from high cell temperature that can be overcome by different active or passive cooling approaches. Spectral splitting and the elimination of high-energy solar photons are effective solutions for cell temperature reduction. In this study, we developed a Polymethyl methacrylate Spectral Splitting Fresnel Lens (SSFL) for linear concentration using a new design, which directs the desired portion of the spectrum towards the cell and diffracts the rest to eliminate the use of beam splitters or nanofluids in the spectral splitting system. Different SSFLs were considered for...
Investigation of precursors concentration in spray solution on the optoelectronic properties of CuInSe2 thin films deposited by spray pyrolysis method
, Article Journal of Materials Science: Materials in Electronics ; Volume 32, Issue 21 , 2021 , Pages 25748-25757 ; 09574522 (ISSN) ; Ghorashi, S. M. B ; Tajabadi, F ; Taghavinia, N ; Sharif University of Technology
Springer
2021
Abstract
Copper indium selenide CuInSe2(CISe) thin films were deposited by chemical spray pyrolysis (CSP) method of CuInS2(CIS) and subsequent selenization process. To study the effects of solution concentration, we prepared different precursors solution of CIS including different amount of indium salts from 0.025 to 0.100 M with In/Cu 1.25 and S/In 4. These results propose that solution concentration is critical for inflecting the morphological, optical, electrical, and electrochemical characteristics of solution-processed CISe films and device performance. The studied morphological properties of deposited samples were homogenous, crack-free with large grains in indium salt concentrations more than...
Theoretical study of diffusional release of a dispersed solute from a hollow cylindrical polymeric matrix
, Article Scientia Iranica ; Volume 28, Issue 3 , 2021 , Pages 1428-1435 ; 10263098 (ISSN) ; Tajsoleiman, T ; Abdekhodaie, M. J ; Sharif University of Technology
Sharif University of Technology
2021
Abstract
The present study proposes an exact solution for the release kinetic of a solute from inside a hollow cylindrical polymeric matrix into an infinite medium when the initial concentration of the solute (A) is greater than the solubility limit (Cs). A combination of analytical and numerical methods was used to calculate the solute concentration profile and the release rate. The model was developed for two different conditions including: (1) The release medium was flowing through the hollow cylinder in which the boundary layer may be neglected, and (2) The release medium inside the hollow cylinder was stagnant where the boundary layer needed to be considered. The results indicated that the...