Sharif Digital Repository

Relative novelty and wide functionality of ionic liquids (ILs) have led to a surge in the studies devoted to experimental determination of their physicochemical properties. Systematic collection and analysis of the available data and development of predictive models to address the extreme diversity of IL systems are of great value in this regard. In the present work, the significance of speed of sound in ILs and their mixtures was outlined and related theoretical concepts were surveyed. A comprehensive database was utilized for the construction of predictive models based on least square support vector machine. By constructing four different models, the influence of temperature, molecular... 

In this paper, we present our results about simulation of 2D-EOF in Nano/Micro scales porous media using lattice Boltzmann method (LBM) in micro-channel for EOF. The high efficient numerical code use strongly high nonlinear Poisson Boltzmann equation to predicate behavior of EOF in complex geometry. The results are developed with precisely investigation of several effective parameters on permeability of EOF, such as geometry (channel height and number and location of charge), external electric field, thickness of Debye length (ionic concentration), and zeta potential. Our results are in excellent agreement with available analytical results. Our results show that for certain external electric... 

In recent years, application of porous media is highlighted among researchers due to their wide range of usability in micro-scale problems, such as gas reservoirs, micro-filtering, heat exchangers, etc. With this respect, the accurate description of flow behavior using governing equations based on the continuum assumption is not valid since the mean free path is comparable to the characteristics length of the problem. For this purpose, a simple methodology for diffusion reflection boundary condition is developed and validated for two valuable benchmarks, namely micro-channel flow and fractal porous media, where the results were in good agreement with literature. Then, pore-scale simulation... 

Due to the widespread use of rarefied gas flow in micro-porous media in industrial and engineering problems, a pore-scale modeling of rarefied gas flow through two micro-porous media with fractal geometries is presented, using lattice Boltzmann method. For this purpose, square- and circular-based Sierpinski carpets with fractal geometries are selected due to their inherent behavior for real porous media. Diffusive reflection slip model is used and developed for these porous media through this study. With this respect, the planar Poiseuille flow is selected as a benchmark and validated with the literature. The effect of Knudsen number (Kn) on the permeability is investigated and compared in... 

Due to the widespread use of rarefied gas flow in micro-porous media in industrial and engineering problems, a pore-scale modeling of rarefied gas flow through two micro-porous media with fractal geometries is presented, using lattice Boltzmann method. For this purpose, square- and circular-based Sierpinski carpets with fractal geometries are selected due to their inherent behavior for real porous media. Diffusive reflection slip model is used and developed for these porous media through this study. With this respect, the planar Poiseuille flow is selected as a benchmark and validated with the literature. The effect of Knudsen number (Kn) on the permeability is investigated and compared in... 

Asymmetric sheet rolling is simulated by using an elastic-plastic arbitrary Lagrangian-Eulerian (ALE) finite element method. The ALE finite element approach easily predicts the curvature development due to inequality in work roll/plate surface finish (interface friction) and speed mismatch. An isotropic work hardening material is assumed. Reasonable agreements were found between the numerical method and the experimental results. © 2006 Elsevier B.V. All rights reserved  

Recently, very large eddy simulation approach has attracted a great deal of attention among researchers. This approach can be thought of as an intermediate approach in flow field filtering view point compared with Direct Numerical Simulation and Reynolds-Averaged Navier-Stokes. One famous method to this approach is Partially Averaged Navier-Stokes. Early studies have demonstrated the capability of this technique in flow prediction; however, this method still needs to be evaluated under more flow conditions to ensure its reliable performance. In this study, the performance of PANS k-ω method in the simulation of turbulent flow around a cylinder with square cross section close to a flat... 

The flow hydrodynamic effects and film cooling effectiveness placing two small coolant ports just upstream the main jet (combined triple jets) were numerically investigated. Cross sections of all jets are rectangular and they are inclined normally into the hot cross-flow. The finite volume method and the SIMPLE algorithm on a multiblock nonuniform staggered grid were applied. The large-eddy simulation approach with three different subgrid scale models was used. The obtained results showed that this flow configuration reduces the mixing between the freestream and the coolant jets and hence provides considerable improvements in film cooling effectiveness (both centerline and spanwise averaged... 

The present study provides an accurate simulation of velocity and temperature distributions of inhalation thermal injury in a human upper airway, including vestibule, nasal cavity, paranasal sinuses, nasopharynx, oropharynx, larynx, and upper part of main bronchus. To this end, a series of CT scan images, taken from an adult woman, was used to construct a three dimensional model. The airway walls temperature was adjusted according to existing in vivo temperature measurements. Also, in order to cover all breathing activities, five different breathing flow rates (10, 15, 20, 30, and 40. l/min) and different ambient air temperatures (100, 200, 300, 400, and 500. °C) were studied. Different flow... 

In the present study, the effect of nanosized graphene oxide layer on thermal stability and biocompatibility of gold nanorods has been examined. The graphene oxide-wrapped gold nanorods were prepared by electrostatic interaction between negatively charged graphene oxide and positively charged nanorods. The resulting nanohybrids were then heated at different time intervals to 95 °C in a water bath to assess the effect of heat on the rods morphology. The structural changes in gold nanorods were monitored via UV-Vis spectroscopy measurements and transmission electron microscopy images. In similar experiments, the graphene oxide used to wrap gold nanorods was reduced by ascorbic acid in a 95 °C... 

In the present study, the effect of nanosized graphene oxide layer on thermal stability and biocompatibility of gold nanorods has been examined. The graphene oxide-wrapped gold nanorods were prepared by electrostatic interaction between negatively charged graphene oxide and positively charged nanorods. The resulting nanohybrids were then heated at different time intervals to 95 °C in a water bath to assess the effect of heat on the rods morphology. The structural changes in gold nanorods were monitored via UV-Vis spectroscopy measurements and transmission electron microscopy images. In similar experiments, the graphene oxide used to wrap gold nanorods was reduced by ascorbic acid in a 95 °C... 

Mechanical ventilation (MV) can result in long-term brain impairments that are resistant to treatment. The mechanisms underlying MV-induced brain function impairment remain unclear. Since nasal airflow modulates brain activity, here we evaluated whether reinstating airflow during MV could influence the memory performance of rats after recovery. Rats were allocated into two study groups: one group received rhythmic air-puff into the nasal cavity during MV and a control group that underwent ventilation without air-puff. During MV, air-puffs induced time-locked event potentials in OB, mPFC and vHPC and significantly increased the oscillatory activity at the air-puff frequency. Furthermore, in... 

Anxiety is prevalent in asthma, and is associated with disease severity and poor quality of life. However, no study to date provides direct experimental evidence for the effect of allergic inflammation on the structure and function of medial prefrontal cortex (mPFC) and amygdala, which are essential regions for modulating anxiety and its behavioral expression. We assessed the impact of ovalbumin (OVA)-induced allergic inflammation on the appearance of anxiety-like behavior, mPFC and amygdala volumes using MRI, and the mPFC-amygdala circuit activity in sensitized rats. Our findings exhibited that the OVA challenge in sensitized rats induced anxiety-like behavior, and led to more activated...