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Probiotic products highly affect the health of consumers by reducing the risk of heart attacks and improving the desirable microflora in the intestinal tract. In this study the effect of yogurt (500g/d for 3 wk) enriched with either Bifidobacterium bifidum or Lactobacillus acidophilus on the level of cholesterol, Low Density Lipoprotein (LDL) and High Density Lipoprotein (HDL) of serum and as well on the intestinal microflora were investigated in 24 healthy volunteers. Statistical analysis indicated that lower levels of cholesterol and HDL were found after consumption of either one of bio-yogurts as compared to the control states (P<0.05), whereas changes of LDL were not significant. Also, in comparison with control periods the results of microbial counts indicated that the number of fecal coliforms excreted during the consumption of either one of the yogurt types were not noticeable, while the number of Bifidobacterium bifidum and Lactobacillus acidophilus increased significantly (P<0.05).

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As the coefficient of performance and the cooling power of adsorption chillers are low, the irreversibility calculation can identify the sources which limit the increase of performance parameters and effectively be used in association with current performance improvement techniques. Adopting the numerical modeling and calculating the temporal distribution of temperature in adsorber elements, this study measures the exergy destruction in different parts and processes of the adsorbent bed. The results show the maximum exergy destruction rate in isosteric phases, yet the total exergy destruction is low due to the short phase times. The highest total exergy loss is observed in isobaric heating phase due to the high irreversibility of desorption process and also long phase duration. Furthermore the effects of fin height and fin spacing on the exergy destruction of adsorbent bed are investigated. The results show that increasing fin height and fin spacing increase the total exergy destruction; however the dependency of fin spacing on exergy destruction is relatively low.

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Lipid core plaques are the major cause of the vascular stenosis and heart attacks. Accumulation of Low-Density Lipoproteins (LDLs) across the atherosclerotic lesions, leads to the hardening of the arterial wall and causes cross sectional narrowing of the artery. Among different arterial wall models, Multilayer model gives accurate LDL concentration across the layers. In this study LDL accumulation in the four-layer carotid artery is investigated numerically. Navier-Stokes equations along with Darcy’s model for the porous regions and the convection-diffusion mass transport equation are employed. Blood considered as a Newtonian fluid and the artery’s wall is assumed to be a porous rigid medium. Due to the negligible pulsatile effect of the flow on the LDL concentration, equations are solved in the steady state condition. In this paper LDL concentration across the layers is considered under normal blood pressure to examine effects of the LDL’s size and the hypertension on the LDL accumulation. Furthermore, a comparison between normal endothelium and the leaky junction is performed. Results indicate that the normal endothelium plays a crucial role in prevention LDL accumulation in the arterial wall.

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During the past few decades, growing global concern about environmental problems, caused by widespread use of fossil fuels, attracts more research attention toward adsorption systems technology. However, one of the main problems of these systems is the poor heat transfer rate in adsorbent bed due to its low thermal conductivity. In the present study, extended surfaces and metal piece additives are applied to the adsorbent bed in order to numerically investigate the effect of heat transfer enhancement on the adsorption system performance. Employing metal pieces increases effective thermal conductivity of the bed by at least 100%. Results indicate that decreasing fin space and fin height and adding metal pieces to the adsorbent bed reduce the cycle time which finally improves the system specific cooling power. However, it is worth mentioning that the effect of metal piece additives on the cycle time reduction and specific cooling power improvement decreases at smaller fin spaces. Moreover, results show that the increase of fin height improves the coefficient of performance while decreases the specific cooling power of the system. On the contrary, the reduction of fin space simultaneously increases the coefficient of performance and the specific cooling power of the adsorption system.

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Numerical modeling of electro-osmotic flow in heterogeneous micro-channels using two different models is presented in this article. For the through modeling of such flows, the coupled equations of Navier-Stokes, Nernst-Planck and the Poisson-Boltzmann are solved for the flow field, electric charges transport and electric field, respectively. Numerical solution of these equations for the heterogeneous micro-channels is complicated and difficult. Therefore, simple and approximate models such as Helmholtz-Smoluchowski have been proposed in which the solution of Poisson-Boltzmann, Nernst-Planck are neglected and the effect of the electric field on the flow field is applied through a prescribed slip boundary condition at the walls of micro-channel. The electro-osmotic flow fields within the heterogeneous micro-channels are usually complex and contain the vortex region that is ideal for mixing purpose. Hence, in this paper, the micro-channels designed so that they are capable to serve as micro-mixers in the mixing applications. For the micro-channels proposed here, the flow fields are obtained both with approximate modeling and the full simulation of electro-osmotic flows so that a comparison can be made to discuss the accuracy of the approximate model. The results of this study can be used to model the electro-osmotic flow field within heterogeneous micro-channels.

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In this paper, a numerical study has been performed to investigate the effect of geometrical parameters of a viscous micro-pump on the flow rate and entropy generation. The present research has been carried out for three geometrical parameters of micro-pump including eccentricity (), sizes (S) of rotors and also their distance from each other (L) in the range of 0.1 to 0.9, 1.5 to 3.5 and 0.85 to 4.5, respectively. The results show that with increasing , the micro-pump flow rate also increases. On size variation effects, it is observed that decreasing the downstream rotor diameter, while keeping constant the upstream rotor diameter, the flow rate decreases exponentially. By increasing L, a steep increase in flow rate is initially observed, which becomes almost constant, when rotors are sufficiently far apart. With regard to entropy analysis, the effect of above geometrical parameters has been investigated on the entropy generation. The parameter RS indicating the ratio of the gradient of the entropy production rate to the related flow rate is introduced as a tool for entropy analysis. Also in this paper, for obtaining the maximum flow rate at the minimum frictional dissipation, optimal geometrical parameters are extracted. In this regard, the values of L=2, ε=0.5, S_1=1.5 and S_2=2.5 are selected as the optimum geometrical parameters of viscous micro-pump.

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Mixing within electrokinetic micromixers is studied numerically in this article. Micromixer studied here is simply a heterogeneous parallel plate microchannel which is imposed to the electroosmotic flow field. For the through modeling of such flows, the coupled equations of Navier-Stokes, Nernst-Planck, Poisson-Boltzmann and concentration equations are solved for the flow motion, electric charges transport, electric field and species concentrations, respectively. Numerical solution of these set of equations for the heterogeneous microchannels is complicated and difficult. Therefore, simple and approximate model such as Helmholtz-Smoluchowski has been proposed which is basically appropriate for the case of microchannels with the homogenous properties on the walls. Validation of Helmholtz-Smoluchowski model is well-examined for the prediction of two dimensional flow fields, yet its applications is rarely validated for the prediction of concentration field and mixing performance. In this article mixing due to electroosmotic flow field is investigated using Nernst-Planck equations as well as Helmholtz-Smoluchowski models and the accuracy of the Helmholtz-Smoluchowski model is evaluated. Comparison of the results indicates that for the proper conditions, approximate model can predict the mixing performance accurately along the micromixer length.

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In this article numerical simulation of electroosmotic flow in heterogeneous microchannel is performed using approximate model of Helmholtz-Smoluchowski in which the effect of electric field on the fluid flow is applied through a slip boundary condition. Solving the concentration equation, the mixing performance of microchannels with heterogeneous zeta-potential is studied both qualitatively and quantitatively. This study shows that combining the electroosmotic and pressure-driven flows in a single microchannel with proper arrangement of the heterogeneities can easily lead to design of electroosmotic micromixers with adjustable mixing performance. The mixing behavior of such micromixers is dominated by the arrangement of zeta-potential distribution as well as the applied external pressure drop. In this article we introduced relative mixing performance and mixing capacity rather than well-discussed factor of mixing performance in order to perform a thorough analysis of mixing. Using these factors, it is found that presence of heterogeneities has a small augmentation on mixing performance when the pressure drop is extremely small or large. Therefore, performance of micromixers with combined flow of electroosmotic and pressure-driven has an optimum point. Furthermore, it is seen that asymmetric level of the charge pattern is more effective on the mixing performance compared to absolute values of wall charges. This promises proper mixing even when surfaces with moderate zeta-potential are used in micromixer.

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In present paper, a numerical study is performed for analysis of effects of geometrical and operational parameters of viscous micropump with the approach to Entropy Generation Minimization by Lattice Boltzmann Method. In study of effect of change in the geometric parameter L and operational parameters ∆P*, it was found that in all ∆P*s, two range of L=1.2 - 1.6 and L=4.4 - 4.8 at EGM viewpoint and two range of L=1.1 - 1.6 and L=4.4 - 4.9 at the minimum power of rotors viewpoint are introduced as optimum ranges. Due to the full overlap of optimum ranges at the EGM viewpoint with the minimum power of rotors viewpoint, the same range mentioned in the EGM viewpoint is selected as the optimal range. Results of the effect of change in the geometric parameter L and operational parameters Re showed that in all Res, two range of L=1.1 - 1.5 and L=4.5 - 4.9 at the EGM viewpoint and two range of L=1.2 - 1.6 and L=4.4 - 4.8 at the minimum power of rotors viewpoint are introduced as optimum ranges. Therefore, the common range of these viewpoint namely L=1.2 - 1.5 and L=4.5 - 4.8 can be selected as the most optimal range. Regarding the effect of change in the geometric parameter ε and operational parameters Re and ∆P* is determined in all Res and ∆P*s, the range of ε = 0.1 – 0.5 is selected as optimum range in the EGM viewpoint and the minimum power of rotors viewpoint.

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Vertebrobasilar system stenosis is one of the risk factor for deaths caused by stroke, the risk of stenosis in these arteries are highly depend on the people’s age. In the present study, atherosclerosis susceptible sites in vertebrobasilar system at different ages 20, 50 and 70 have been investigated. Numerical method (Fluent software) is employed to solve the equations. Blood flow is simulated in these arteries to investigate probable risky sites (prone to stenosis). To find these locations, critical values of the averaged wall shear stress (AWSS) and oscillatory shear index (OSI) have been studied. By considering the AWSS and OSI criteria in 20 years old person it becomes clear that the risk of stenosis is not considerable at this age, somehow ageing increases OSI figures in the right vertebral artery and in its junction reaching to the critical values, besides at this age, the area of the sites with lower amount of AWSS are stretched significantly. At the age of 70, risky sites are expanded toward right vertebral artery. Furthermore the risk of stenosis in all determined risky sites of age 50 increased at the age of 70.

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In this paper, simultaneous impact of two parallel drops on a thin liquid film is investigated using the lattice Boltzmann method. The purpose of this study is to investigate the effects of surface tension (characterized by Weber number), distance between two drops, and gas kinematic viscosity on the impact. The developed numerical model in this paper which is based on the Shan and Chen pseudo-potential two-phase model makes it possible to access large density ratios, low viscosities, and tunable values of surface tension independent of the density ratio. The model is validated by comparing the coexistence densities with those of Maxwell analytical solution, evaluating the Laplace law for a droplet, and simulating single droplet impact on a thin liquid film. Simulation results of two drops simultaneous impact show that after impact, two jets raised between the drops join each other and form a central jet. Height of this jet increases with time leading to separation of secondary droplets from its tip. When the surface tension value is decreased, the central jet height is increased, but size of the separated droplets is reduced. The crown shape observed in single drop impact is also seen in simultaneous impact of two drops. Increasing distance between two drops leads to a smaller central jet height and an increase in the crown radius. The crown height, however, was found to be independent of the distance. Finally, increasing gas kinematic viscosity reduces the central jet rising speed and delays separation of secondary droplets from the jet.

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Large amount of diesel engine waste heats make researchers design systems that utilize the engine waste heat to provide the cooling demand of the heavy-duty vehicles and improve the engine efficiency. Considerable advantages of adsorption cooling system lead to be nominated for this purpose. Coolant and exhaust gases are the main sources of waste heats of diesel engines and using each of them to drive the adsorption cooling system requires its own equipment and working pair. In this paper, a detailed numerical model has been developed and to examine the performance of the cooling system driven by the coolant waste heat with working pair of silica gel-water and also driven by exhaust waste heat with zeolite13x-water working pair. An identical absorbent bed and ambient conditions have been employed to compare the performance of both systems to identify the more appropriate system. The results show that exhaust driven adsorption cooling system has more capability to meet the vehicle cooling demand. Moreover, the performance of the both adsorption cooling systems were examined under variable ambient condition. Results indicate that increase in ambient temperature leads to almost a linear performance drop in both systems that is more considerable in the coolant- driven adsorption system.

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The interactions between vortical structures and spherical particles or droplets is of practical issues in two-phase flows. The interactions bring major changes in the flow field particularly when coupled with particle rotation. It is observed that the heat transfer rate is significantly influenced during the time that the vortices’ cores are in the vicinity of the particle. In this paper, transient heat transfer of a rotating spherical particle interacting with a pair of vortices in incompressible and viscous flow is studied using numerical solution of the Navier-Stokes and energy equations in the range of 20≥Re≤100 and non-dimensional rotational velocities 0≤Ω≤1, by computational code which has been developed by the authors. In order to ensure the accuracy of the calculation, the results are compared with numerical data reported in the literature and good agreement between results was observed. Then the effect of circulation direction of two vortices interacting with a particle by spin on its heat transfer rate was investigated. Also distribution of heat transfer coefficient at the particle surface with separate rotation around three different axes in two cases of interacting and non-interacting with vortices is given and the results of heat transfer coefficient are presented. The results show that particle rotation for Ω≤0.5, in both presence and absence of vortices in flow field has negligible effects on the particle heat transfer rate; however, with increasing of particle spin significant effects on heat transfer coefficient has been observed that due to the circulation direction of vortices, different amounts are obtained.

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Injection drug micro particles into arteries is one of the stenosis treatments. Micro particles scattered in blood flow collide with plaques, drug is absorbed to treat stenosis. Since the collision of drug particles with artery wall depends on blood flow pattern, the efficiency of this method relies on guiding drug particles to stenosed site, otherwise the patient must take much higher drug dosage which has various side effects. Applying magnetic field and guiding drug particles to the target area extensively increases efficiency of the treatment and cuts side effects. In the present study, efficiency of using drug particles in vertebrobasilar system to treat atherosclerosis with and without applying magnetic field has been investigated. Ansys-Fluent commercial software has been used for numerical simulation. Results indicate applying magnetic field plays an important role in drug particles circulation as drug captivation surges almost 16 times. Injecting location and the particle diameters also have been examined and found to be important in the treatment effectiveness.

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The considerable amount of internal combustion engine waste heat through exhaust gases and the capability of adsorption cooling system to be driven by waste heats cause adsorption cooling systems to be interesting for vehicle air conditioning. Low specific cooling power of these systems leads them to be bulkier with respect to other cooling systems. Therefore, practical use of these system has been a challenge. One of the methods to enhance the system performance is adsorber bed optimization which is only feasible by numerical simulations. Hence, an exhaust waste heat driven adsorption cooling system with longitudinal finned-tube adsorber is simulated three dimensionally and considering heat and mass transfer details. Also, both the intra-particle and inter-particle mass transfer resistance has been taken into account in governing equations in order to study the effect of adsorbent particle diameter on the system performance. Results show that among the examined geometrical configurations, bed with 20 fin numbers and fin height of 10 mm is the optimum case corresponding to the maximum specific cooling power. In addition, adsorbent particle diameter in the range of 0.3-0.4 mm is the most suitable diameter for the adsorber bed packed with zeolite13x grains.

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In this study, energy and exergy analysis of a two bed adsorption cooling system have been performed. Silica gel-water has been chosen as the adsorbent-refrigerant pair. Analysis is performed for evaluating the effect of operating conditions on the optimal timing and then on the maximum value of the SCP, COP, effectiveness and the minimum value of internal irreversibility and external irreversibility. A lumped parameter mathematical model and a global optimization method called the particle swarm optimization have been used to reach this purpose. In this model, internal and external irreversibility have been calculated with the new method without calculating irreversibility of the cycle internal component. Energy analysis showed that maximum of SCP increases with the increase of the mass flow rate and heat source temperature. Furthermore, an increase in the heat source temperature causes an increase in the COP, but an increase of the mass flow rate causes a decrease in the COP. Exergy analysis reviled that depending on the mass flow rate and heat source temperature, 65-90% of input exergy was expended by internal irreversibility, 1–20% were expended by external irreversibility and 8-14% is transferred to the cold reservoir in evaporator. It is concluded at the low-temperature heat source if the mass flow rate is chosen less than 0.6 kg/effectiveness at heat source temperature 75 is more than 65 and vice versa.

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In the present paper, a numerical study is performed for analysis of 3D effects of geometrical parameters namely microchannel depth, eccentricity and sizes of rotors and operational parameter namely pressure difference on flow flux and efficiency by LBM. In investigation of simultaneously variation effect of geometrical parameters namely rotors eccentricity and microchannel depth is observed in all depths, increasing the eccentricity, both flow flux and efficiency increased. Also, in a constant eccentricity both flow flux and efficiency increased. In the next investigation that simultaneously effect of geometrical parameters namely rotors sizes and microchannel depth is discussed determined that in all depths, decreasing the rotors sizes, flow flux decreased. But for efficiency, it became less in the lower depths and increasing depth the efficiency increased. In final, the effects of operational parameter of pressure difference and geometrical parameter of microchannel depth on flow flux and efficiency has been studied. As the results show, increasing the pressure difference, flow flux linearly decreased so that it became zero at the certain pressure. Moreover, efficiency variations vs. pressure difference parabolically is observed.

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In the present study, for the first time, adsorbent bed of SWS-1L/water adsorption chiller with rectangular and trapezoidal finned flat-tube heat exchanger with has been simulated three dimensionally based on the distributed parameters model and finite volume method. Effects of some important parameters on the chiller performance such as bed averaged pressure, temperature and uptake variations with cycle time have been examined for better understanding of bed dynamic behavior. Also, a comparative study between two different configurations of adsorbent bed including rectangular and trapezoidal fins has been conducted based on identical adsorbent mass. For this purpose, bed temperature, uptake and pressure distributions as well as the vapor flow patterns at the end of heating cycle phases and also effects of fin height and spacing on the system performance have been studied. In this investigation at fixed bed length of 20mm, fin height and spacing variations have been examined in the range of 8-20mm and 3-12mm, respectively. Results indicated that the system performance with rectangular and trapezoidal adsorbent beds are almost similar except for those conditions which fin spacing is 3mm and fin height are 14, 20mm. For the mentioned dimensions, the specific cooling power (SCP) of rectangular beds are almost 5% and 17% (for fin heights of 14 and 20mm, respectively) better than those of trapezoidal beds. Maximum and minimum SCP of adsorption chiller with flat-tube heat exchanger were obtained about 882 and 163W/kg for the smallest and the largest bed geometry and operating conditions considered in this study.

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In present study, the effect of the percentage of meat in the first stage (three levels of 30, 60% and 90%) and replacement of dried milk powder with soybean meal in the second stage on amount of acrylamide formed in grilled beef and chicken burgers (containing 60% meat) was investigated. Also, total sugar, protein, moisture and sensory characteristics of burgers were determined. The results indicated that the amount of acrylamide in chicken burgers was significantly less than that of beef burgers (p <0.05). The highest and the lowest amounts of formed acrylamide related to meat burger 60% (66.03 μg/kg) and chicken burger 90% (26.54 μg/kg), respectively. Further, the increase of the beef and chicken meat content from 30 to 60% led to increase in acrylamide while increasing from 60 to 90% resulted in decrease in the amount of formed acrylamide. The total sugar content of chicken meat burgers was significantly higher than that of beef burgers while their protein content was lower (p<0.05). The results also indicated that increasing replacement of dry milk powder caused to increase in amount of formed acrylamide in the burgers. The highest and the lowest amounts of acrylamide in the second stage related to the beef burger contains 16% dried milk powder (69.25 µg/kg) and chicken burger containing 8% dried milk powder (40.35 µg/kg). It seems the lowest amount of acrylamide in burgers would be formed in present of the chicken burgers containing 90 percent meat without dried milk powder