59 research outputs found

    Experimental and Numerical Investigation of the Efficiency and Pressure Drop of an Inertial Impactor with Variable Area

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    The deposition efficiency and pressure drop of inertial impactor with variable area has been studied numerically and experimentally. The effect of volumetric flow rate, vertical barrier, oblique barrier and flexible concave plate versus deposition and impaction efficiency and pressure drop is investigated. Numerical simulation is carried out with DPM (discrete phase method) and turbulent model of SST k-ω. To validate the numerical results a special test rig is designed to study the deposition efficiency of engine oil droplets (blow-by) with a diameter of 0.1 to 6 µm. Experimental Tests are done in 8, 12, 16 and 20 L/min. To ensure the accuracy of the experimental results, all the tests are repeated at least three times for each volumetric flow rate. Gravimetric method is implemented to calculate the deposition efficiency. According to the results, the deposition efficiency is obtained between 73 and 94 percent for different mentioned impactors and different volumetric flow rate. The numerical results are confirmed by experimental results. Using the barriers increase the efficiency maximum 6 percent in different volumetric flow rate. The results show that by reducing the distance between the vertical barrier and the outlet of nozzle, the deposition and impaction efficiency are increased. Also, the Concave flexible plate with vertical barrier located at 1 mm from the outlet of nozzle is the most efficient case

    Survivin c.-31G>C (rs9904341) gene transversion and urinary system cancers risk: A systematic review and a meta-analysis

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    Aim: To investigate the possible association between survivin c.-31G>C (rs9904341) gene polymorphism and urinary system cancers by a meta-analysis approach. Methods: Standard electronic literature databases were searched to find eligible studies. The odds ratios (ORs) with 95 CIs were estimated to find the associations possibility. Results: Overall meta-analysis revealed significant associations between c.-31G>C transversion and risk of urinary tract cancers in dominant (OR: 1.34; 95 CI: 1.02-1.75; p = 0.035), recessive (OR: 1.52; 95 CI: 1.33-1.74; p C transversion might be a risk factor for urinary system cancers. However, more articles with different ethnicities will help to obtain a more accurate conclusion. © 2018 Future Medicine Ltd

    Improving the Muskingum flood routing method using a hybrid of particle swarm optimization and bat algorithm

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    Flood prediction and control are among the major tools for decision makers and water resources planners to avoid flood disasters. The Muskingum model is one of the most widely used methods for flood routing prediction. The Muskingum model contains four parameters that must be determined for accurate flood routing. In this context, an optimization process that self-searches for the optimal values of these four parameters might improve the traditional Muskingum model. In this study, a hybrid of the bat algorithm (BA) and the particle swarm optimization (PSO) algorithm, i.e., the hybrid bat-swarm algorithm (HBSA), was developed for the optimal determination of these four parameters. Data for the three different case studies from the USA and the UK were utilized to examine the suitability of the proposed HBSA for flood routing. Comparative analyses based on the sum of squared deviations (SSD), sum of absolute deviations (SAD), error of peak discharge, and error of time to peak showed that the proposed HBSA based on the Muskingum model achieved excellent flood routing accuracy compared to that of other methods while requiring less computational time

    Electrochemical Oxidation Assessment and Interaction of 2-aminoethanol and N, N-diethylethanamine Propagation in Acidic Medium

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    Electro�oxidation and inhibitor performance of copper specimens in 1 M hydrochloric acid solu� tion was investigated at room temperature by linear potentiodynamic polarization and gravimetric method in the presence of 2�aminoethanol (A) and N, N�diethylethanamine (D) as an inorganic inhibitor. The effect of the inhibitory concentration on the corrosion behavior of copper was studied over 288 hrs at 298°K. The inhibitory efficiency rise up to 96% for single induced and 98% for synergistic behavior. The adsorption mechanism characteristic was supported by SEM/EDX analysis and adsorption isotherm. From all indica� tion, the inhibitive efficiency of these compounds majorly depends on their molecular structure and concen� tration. The blocking effects of the surface interface were also explained on the basis of the inhibitor active action. 2�aminoethanol and N, N�diethylethanamine inhibits copper in 1 M HCl by strictly affecting both the anodic and cathodic sites. Portion of the surface covered calculated was also found to follow Langmuir adsorption isotherm

    Association of A-197G polymorphism in interleukin-17 gene with chronic periodontitis: Evidence from six case-control studies with a computational biology approach

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    AIM: The aim of the present study was to evaluate the association of interleukin-17 (IL-17) A-197G gene polymorphism with chronic periodontitis (CP) in a case-control study, a meta-analysis, and an in silico approach. METHODS: In the case-control study, 122 cases with CP and 126 healthy controls were recruited; IL-17 A-197G genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism. In the meta-analysis, comprehensive literature retrieval was performed on valid databases to identify relevant studies. Bioinformatics tools were employed to investigate the effects of A-197G transition on the promoter region of IL-17. RESULTS: Our case-control study revealed a significant association between IL-17 A-197G transition and CP. The overall meta-analysis revealed significant associations between the IL-17 A-197G polymorphism and CP risk in homozygote co-dominant and recessive models. The stratified analysis also showed a statistically significant association between the mentioned transition and CP risk in the Caucasian population. The in silico analysis revealed that the A-197G polymorphism could make changes in protein-binding sites of the IL-17 promoter region. CONCLUSIONS: Our study supports that IL-17 A-197G transition could be a genetic risk factor for CP. However, further studies with a larger sample size among different ethnicities are required to obtain a more accurate conclusion. © 2019 John Wiley & Sons Australia, Ltd

    MHD Natural Convection and Entropy Generation of Variable Properties Nanofluid in a Triangular Enclosure

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    Natural convection heat transfer has many applications in different fields of industry; such as cooling industries, electronic transformer devices and ventilation equipment; due to simple process, economic advantage, low noise and renewed retrieval. Recently, heat transfer of nanofluids have been considered because of higher thermal conductivity coefficient compared with those of ordinary fluids. In this study; natural convection and entropy generation in a triangular enclosure filled by Al2O3 –water nanofluid affected by magnetic field considering Brownian motion is investigated numerically. Two inclined walls are maintained at constant cold temperature (Tc) while the bottom wall is kept at constant high temperature (Th) with (Th>Tc). In order to investigate natural convection, a computer program (FORTRAN language) based on finite volume method and SIMPLER algorithm has been used. Analyses is performed for volume fraction of nanoparticles 0, 0.02, 0.04, Hartmann number 0, 50,100, Rayleigh numbers 103,104,105 and angle of inclined walls 450. In investigated angles and Rayleigh numbers; average Nusselt number is increased by enhancement of volume fraction of nanoparticles in a fixed Hartmann number. It is also observed that total entropy generation variations by increasing volume fraction of nanoparticles is similar to that of Nusselt number. By the results; effect of friction is always insignificant on generated entropy. It is observed that natural convection of nanofluid is decreased by enhancement of Hartmann number and its behavior is close to thermal conduction. It is also concluded that average Nusselt number and total generated entropy are decreased

    CYP1A1 and GSTs common gene variations and presbycusis risk: a genetic association analysis and a bioinformatics approach

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    Antioxidant enzymes such as glutathione S-transferases (GSTs) and cytochromes P450 (CYPs) are involved in the metabolism and detoxification of cytotoxic compounds, as well as the elimination of reactive oxygen species (ROS). Therefore, alterations in the structure of these enzymes could result in prolonged production of ROS with subsequent risk of development of disorders such as presbycusis. This study aimed to investigate the association between CYP1A1 (rs4646903, rs1048943) and GSTs (GSTM1-deletion, GSTT1-deletion, GSTP1-rs1695) with presbycusis risk in an Iranian population which was followed by an in silico approach. In a case-control study, 280 subjects including 140 cases with presbycusis and 140 healthy controls were enrolled. Genotypes of single-nucleotide polymorphisms (SNPs) were detected by PCR-RFLP method and the genotype of the above mentioned deletions was determined by touchdown PCR. Some bioinformatics tools were employed to evaluate the impact of SNPs on the gene function. SNP analysis revealed that there are significant associations between rs1048943 (AG vs. AA: OR = 2.46, 95CI = 1.30–4.65, p = 0.006; GG + AG vs. AA: OR = 2.53, 95CI = 1.36–4.69, p = 0.003; G vs. A: OR = 2.36, 95CI = 1.33–4.17, p = 0.003) and rs4646903 (C vs. T: OR = 1.45, 95CI = 1.02–2.06, p = 0.040) variations and increased risk of presbycusis. However, there was no significant association between rs1695 and presbycusis risk. Also, significant associations were observed between GSTM1 (OR = 4.28, 95CI = 1.18–15.52, p = 0.027) and GSTT1 (OR = 1.64, 95CI = 1.02–2.65, p = 0.041) deletions and elevated risk of presbycusis. Moreover, the combination analysis revealed a significant association between GSTM1+/GSTT1− genotype and presbycusis susceptibility (OR = 1.63, 95CI = 1.00–2.67, p = 0.049). In silico analysis revealed that the rs1048943 SNP could influence significantly on the RNA structure of CYP1A1 (distance: 0.1454; p value: 0.1799). Based on our findings, the rs4646903, rs1048943 SNPs as well as GSTM1 and GSTT1 deletions could be considered as genetic risk factors for the development and progression of presbycusis. © 2020, Springer-Verlag GmbH Germany, part of Springer Nature

    Analysis of Adsorption, Ion Exchange, Thermodynamic Behaviour of Some Organic Cations on Dowex 50WX4-50/H+ Cation Exchanger in Aqueous Solutions

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    The equilibrium adsorption, ion exchange characteristics of various concentrations of some organic cations from aqueous solutions onto dowex 50WEX/H+ cation exchanger were studied at different temperatures in the range of 30-50 °C. The studied cations showed good adsorptive properties onto dowex 50WX4-5/H+ at different concentrations and temperatures. Main adsorption behaviour was ion exchange between hydrogen ions and the organic cations as indicated from the linear relation between the initial concentration of the organic cations and the released hydrogen ions. It was found that the adsorption affinity of dowex 50WX4-50/H+ towards the studied organic cations depends on the substituent type of the organic cations giving the following increasing order: 1-H < 2-OH < 3-OCH3. Thermodynamic parameters for the adsorption of the studied organic cations were evaluated and discussed. It was found that the adsorption 1-H organic cation was spontaneous, ordered, exothermic and favored with decreasing temperature. On the other hand the adsorption of both 2-OH and 3-OCH3 organic cations was found to be spontaneous and disordered with enthalpy change varies significantly with increasing organic cation concentration, suggesting dipole-dipole adsorption forces as new active sites for adsorption under conditions of relatively high concentrations. Freundlich and Dubinin-Radushkevich adsorption isotherm models reasonably describe the adsorption of the studied organic cations onto dowex 50WX4-50/H+ by segmented straight lines depending on the studied range of concentration, indicating the existence of two different sets of adsorption sites with substantial difference in energy of adsorption. According to Dubinin-Radushkevich adsorption isotherm model, physical-ion exchange mechanism was suggested for the adsorption of 1-H organic cation and both physical and chemical-ion exchange mechanisms were suggested for the adsorption of 2-OH and 3-OCH3 organic cations depending on the studied range of concentration

    Effects of two months of physical activity on the copper level of overweight sedentary young male and female measured at nano scale level

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    Many chemical elements at trace level in human body play vital role in health and Copper is one of them. Exercise changes the level of many chemical elements. The purpose of this research was to examine the effects of exercise on the copper level of overweight male and female measured at nano scale level.23 healthy overweight young male and female performed aerobic exercise two times per week. The blood sample was collected prior to the start and at the end of the program. They performed submaximal exercise. Statistical analysis using t-test indicated that there was a significant increase in the level of copper of both groups (P=0.07, P =0.0001).No significant difference between the level of copper between the men and women in posttest was present. No significant differences between the pretest and posttest level of copper in both groups was found (p>0.05). The results demonstrated that two months of exercise increased the level of serum copper in male and female subjects. Therefore, there is no change in hemostasis level of the subjects who participate in this kind of activity and there no need to consume supplementary copper during the physical activity exercise

    Testosterone cortisol ratio after two months regular training on obese female students

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    Testosterone controls and stimulates muscle, bone, skin, and the majorities of human characteristics. Cortisol protects the body against sudden changes through the control of carbohydrates, protein, and fat metabolism. The purpose of this research was to examine the ratio of testosterone to cortisol following an aerobic activity in fat women. Twenty healthy volunteer female subjects (BMI>29) participated in this research. The subjects performed 8 weeks of running program. Blood sample was collected at the start and termination of the protocol. Statistical analysis including independent t-test and Person correlation procedure was used. The testosterone level different following the aerobic exercise (P=0.6). Significant difference was observed between the cortisol level after the exercise program (P=0.008). In addition, no significant differences was present between the testosterone level of the experimental and control group upon the termination of the exercise program (P=0.89). Significant difference was found between the cortisol level of the experimental and control group after the exercise program (P=0.0001). The ratio of testosterone to cortisol was 0.002 nanogram in pretest and changed to 0.005 after the exercise program. The concentration of cortisol decreased. perhaps the intensity of the activities were not high enough to increase the concentration of cortisol level and cause the destruction of muscle cells. Considering the lower level of women in female compared to men, the concentration of this variable remains unchanged following two months of aerobic exercise. As a result, two months of exercise can not lead to stress on testosterone hormone
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