mojtaba shafiee

The performance of surfactants especially in two-phase systems, depends on their type, Hydrophile-Lipophile Balance (HLB) number, concentration, and whether the surfactant is ionic or non-ionic. The current work was conducted to study the effect of the presence of Cetyltrimethylammonium Bromide (CTAB), a cationic surfactant, in air-water systems. Thus, the behavior of a single air bubble rising in aqueous CTAB solutions was studied experimentally. The independent test variables are solution concentration (0.4-1.6mM) and bubble diameter (3.5-4.6mm). The effect of these variables on rising velocity, bubble shape, and drag coefficient has been studied. Due to the importance of the drag coefficient in two-phase fluid, the effect of Reynolds number, Eötvös number, and aspect ratio on it has also been evaluated. Experiments have been performed at high Reynolds numbers (850<Re<1000), which are obtained by increasing the surfactant concentration. The results showed that the selected ionic surfactant had a more tangible effect on bubble behavior than nonionic surfactants. Moreover, there is no noticeable difference in the behavior of the bubble rising at concentrations above and below of Critical Micelle Concentration (CMC) of CTAB, which can be attributed to its high aggregation number compared to other surfactants.

Today, energy plays an important role in the economic growth of human societies. Among the types of energy consumed by humans, solar energy can be considered the most abundant. Therefore, over the years, various types of solar water heating systems have been developed and used. Considering the remarkable capabilities of nanofluids in improving heat transfer processes and increasing the thermal efficiency of heating systems, the use of nanoparticles as a substitute for conventional fluids in various heating systems, especially solar energy systems, as well as the effect of widely used nanofluids So much attention has been paid to increasing the thermal efficiency of the solar vacuum tube collector. In this research, the most important component, namely the efficiency of solar water heaters and also the heat transfer process using three types of nanofluid (with mass percentage 1%), has been investigated. All tests were performed in accordance with the relevant standards (ISO-9806), on sunny days. The highest increase in heat transfer of nanofluids and also the thermal efficiency of the system is related to noon (religious noon), among which, the highest efficiency is related to aluminum oxide nanofluid (AL2O3 nanofluid), with a 3.46% increase compared to the base fluid (Oil fluid) is. The thermal efficiency of the system with titanium oxide nanofluid (TiO2 nanofluid) and carbon oxide nanofluid (C nanofluid) as well as the base fluid (oil fluid) show 2.54%, 2.12% and 1.6%, respectively. Due to the increase in heat capacity of the nanofluids used, the heat capacity can be considered an important factor in increasing the efficiency of vacuum tube solar water heaters.

Today, the discussion of droplet-fluid interaction is one of the most challenging topics in multiphase (liquid-liquid) flows. In the present study, the behavior of two edible oils (olive oil and canola oil) droplets during the rising in the static fluid of water and passing through the water-oil interface was experimentally investigated. Droplet diameters were controlled in the range of 3.8 to 5.6 mm. First of all, the range of dimensionless numbers was compared to experimental data from other researchers and validated. The results revealed that the droplet shape is elliptical, and that the Weber number decreases in the range of 1 to 2, as the aspect ratio increases. Furthermore, the droplet residence time at the two-phase interface was measured, and the parameters that affected it were examined. Although the results showed that the residence time did not follow a consistent pattern, the conclusion was not far off. Weber dimensionless number was used to introduce hydrodynamic forces and internal surface tension of the droplets. It was shown that none of the theoretical relationships can accurately or even roughly predict the residence time of the oil droplets. Finally, the Weber number has been proven to be dependent on the droplet terminal velocity. Terminal velocity increases with the Weber number and the equivalent diameter.

Todays, the discussion of the droplets interaction with fluid is one of the most challenging topics in multi-phase (liquid-liquid) flow. In the present work, an experimental study was done to investigate the oil droplet rising through a stagnant fluid water and crossing the water-oil interface. Thus, an image recording and processing have been used. The employed oil in the experiments is a heavy crude oil extracted from an Iranian oil reservoir and the drop diameter is controlled in the range of 2 to 3mm. Firstly, the range of the obtained dimensionless numbers was compared and validated with the experimental data of the other works. The results showed that in the applied conditions, the drop shape is ellipse-like and the Weber number decreased by increasing aspect ratio. Moreover, residence time versus drop diameter did not follow a uniform procedure. Finally, the best correlation was introduced to predict the residence time of oil droplets by comparing the experimental results with the presented empirical equations

In this research, some brake pads have been produced by in situ polymerization method and dispersion of Nano clay (Montmorillonite) in a phenolic resin matrix. They possess a long life besides having a smooth and reliable braking ability. The optimum amount of Nano clay was determined to be 2/5% to prevent Nano clay molding and results in its uniform distribution in the phenolic resin bed, as well as increasing the mechanical properties of the brake pad. According to the results of the tests, in two formulations of the same brake pad, one without a Nano clay and the other containing Nano clay, the bending from 70 MPa to 76 MPa, the hardness of the samples from 83 to 91 (shore A), abrasion of samples from 4.2308 × 10 -7 to 3.8674 × 10-7, and the coefficient of friction from 0.228 to 0.232 have been changed, respectively.

The heat transfer coefficient of a fluid is one of the most important effective factors on the performance of a fluid in the heat transfer process. Due to the higher conductive heat transfer coefficient of metals than liquids, metal particles can be used to increase the heat transfer rate of liquids. Nano fluid is one of the novel and developing methods to improve heat transfer rate in heat exchangers. In this paper, the main effective parameters on increasing the convective heat transfer coefficient of carbon nano fluid compared to water as based fluid, including: flow rate and concentration, in the range of 7100 to 16700 for Reynolds which is known as turbulent flow, are investigated. The results illustrate that increasing in Re number leads to increase the Nusselt number and convective heat transfer coefficient, and moreover decrease the friction factor. It is also showed that in a constant Re, carbon nano fluid has been able to create up to 10.17% more convective heat transfer coefficient, compared with pure water as base fluid. It was found that adding Carbon nano-particles to water, initially leads to increase in the convective heat transfer coefficient of the nanofluid. This increase continues to a concentration of about 0.2 wt% of the nano-carbon, and then has a descending trend. In addition, the pressure drop due to changes in Re, was investigated too, and showed that the behavior of this curve is in agreement with Moody’s diagram.

Energy is an important parameters for sustainable development of each country. Renewable energies are one of the main ways to reach this aim. Photovoltaic (PV) power plants is one of the most popular renewable power generation methods that is available in most parts of the world. Rising the PV cell temperature is one of the proved weak points which negatively affects their electricity production. Different ways have been proposed in order to degradation of temperature effects on PV cells. One of them, is using phase change materials (PCMs) to prevent the rapid rise of the temperature of PV modules. PCMs absorb parts of temperature of cells, which is leads to decrease the PV temperature. Several methods were presented in PV/T field based on PCMs. The main purpose of this paper is to introduce the major coolant ways of PV modules and provides a review of different methods of cooling PV modules by using PCMs. For each section, some suggestions for developing purposes have been presented.

Nowadays, using of renewable sources are popular methods to generating energy. Photovoltaic (PV) technology is one of the most popular ways to producing power. In hot days of year, which the maximum irradiation of sun is available, because of the temperature value is high, the efficiency of PV cells is falls down. In this paper, in order to decrease the temperature of PV cells, using Polyethylene-Glycol 600 (PEG-600) as phase change material (PCM), for cooling the PV panel was studied. The results show the positive effect of fins on controlling the temperature of photovoltaic cells. Moreover, in order to increasing the rate of melting the PCM, integrating some fins was investigated too. The panel with PCM included, in about 80 mins of the end of test, had a same temperature with the conventional panel, as well as panel with both PCM and fins, at the end of experiment, had a temperature difference of about 9°C compared with conventional panel. Furthermore, the maximum efficiency difference between the panel with PCM and panel with PCM + fins, were about 2.4 % and 4.6 %, respectively. This means that fins, due to the increased amount of heat exchange between the panel and PCM, has been able to play an important role to increasing the efficiency and controlling the temperature of the panel. Finally, for economic and industrial feasibility of the proposed prototypes, the economical estimation is also presented.

The drag coefficient is one of the important parameters in studying the characteristics of bubble motion. In the present research, the drag coefficient of single bubble rising in non-Newtonian fluid has been investigated. Polyacrylamide solutions were selected with different concentrations as a Non-Newtonian fluid. As known, these solutions have viscoelastic properties which strongly influence the drag coefficient. This experiment has been done with different nozzle diameters, for three type of gas (Air, and ) at different injection flow rates. Hence, the results are more comprehensive than previous studies. A comparison between the obtained results and the equations in other studies showed that none of these relationships can predict the drag coefficient of a bubble rising in a non-Newtonian fluid with a viscoelastic properties. Therefore, two new correlations have been presented to predict the Drag coefficient based on Reynolds, Archimedes and Eötvös dimensionless number by dimensional analysis. The predicted drag coefficient by the equations is in very good agreement with experimental data. The first equation which obtained directly from the dimensional analysis was simpler than the second equation. The average error of first equation was 3.26%, while, the average prediction error of the second equation was about 1.7%, which is more complex in terms of formulation. In addition, new equations for predicting terminal velocities and the behavior of bubble rising in a non-Newtonian viscoelastic fluid are presented.

The nanofluids have been able to occupy an important place in engineering, in spite of being a young science. While nanoparticles are very effective in increasing heat transfer of base fluids, they cause a significant pressure drop in the flow. In this paper, the effect of different concentrations, 0.1 to 0.4 wt.%, of carbon nanofluid in water have been investigated on the pressure drop of fluid flow over the Reynolds range from 14,000 to 28,000. The variation of pumping power was measured and the corresponding results illustrated increasing in the friction factor of the nanofluid at concentration 0.4  up to 70%, leading to a 68% increase in the pumping power.

In this study, the economical value of flared gases in gas phase 12 gas refinery was investigated. The economy itself has been examined from two perspectives. The first view on the conversion of fired gases to electrical energy and its revenue generation using the McLaren method. In the second view, the volume of flared gases is equivalent to the amount of gas consumed in industries, households and exports. According to the results, the gross profit from flaring gas to electric energy was $ 123,125 per year. The volume of flared gases was equivalent to the consumption volume of power plants at 0.77%, the equivalent of 3.3%, the consumption volume of the industries was 1.24%, and the domestic and commercial consumption was 0.3%, and it should be noted. Carried out in 2017 and 2018.

Neonatal asphyxia is a state of hypoxia and hypercapnia caused by failure to breathe spontaneously and regularly soon after birth. Heat shock proteins (HSPs) are a ubiquitous and diverse group of highly conserved proteins which are rapidly up-regulated following periods of cellular stress including exposure to heat, ultraviolet irradiation, or chemical toxicity. The aim of the current study was to explore whether there is a relation between serum levels of HSP27 and neonatal asphyxia in a small sample of newborns. A total of 25 healthy newborns and 25 newborns diagnosed with neonatal asphyxia were recruited form Imam Reza Hospital, Mashhad, Iran. The Apgar score was recorded at one minute after delivery by trained nurses and newborns with the Apgar score of less than 7 were considered to be asphyctic. The mean birth weight of newborns in the case and control groups were 3110.47±613.5 g and 3230.4±584.83 g, respectively (P=0.4). Moreover, the mean maternal age of infants in the case group was higher than the mean maternal age of infants in the control group (31.1±6.1 vs. 30.1±5.0). Although it was marginally significant, the level of HSP27 was higher in the case group than the control group (0.23±0.08 vs. 0.19±0.09; P=0.07). Levels of HSP27 were found to be higher in newborns with neonatal asphyxia compared with healthy controls.

The electricity generation from renewable sources is growing rapidly. The use of photovoltaic panels is one of the most popular renewable power generation methods that is available in most parts of the world. One of the problems facing to this industry is increasing the temperature of the panels during the hot days of the year; which reduces their output power. The use of phase change materials (PCMs) is a way to prevent the rapid rise of the temperature of the panels. In this paper, polyethylene glycol 600 (PEG 600) is used behind the panel as a PCM. This material, absorbs a portion of the panel's heat and causes to lower the temperature of the panel. In order to enhance the heat absorbed by the PEG600, a number of fins are also mounted on the back of the panel, and the results are compared with the non-fin state. The results show that at the beginning 150 minutes from the start of the experiment, the temperature difference between panel with both PCM and fin compared with conventional panel, is between 18 C and 34.1 C. Furthermore the maximum efficiency difference between the panel with both PCM and fin, with conventional panel is 4.65% and for the panel with PCM and non-fin, with conventional panel is 2.45%. Finally, the comparison of both experimental measurement and analytical calculation were performed.

Obesity is a common health problem associated with a number of diseases, such as hypertension, cardiovascular disease, hyperlipidemia, diabetes, gout, gall bladder and liver disease, cancer, and depression. The prevalence of obesity is dramatically increasing around the world, especially in the Asia Pacific region. omega-3 is a type of polyunsaturated fatty acids that have several beneficial effects on some diseases such as diabetes, hypertension, rheumatoid arthritis, bipolar disorder and asthma. Therefore, the main objective of the present study was to determine the levels of omega-3 fatty acids in subjects with different categories of BMI (healthy- weight, overweight, and obese) and WC (not at risk, increased risk, and substantially increased risk). In the current study, a total of 151 individuals consist of 58 men and 93 women (aged 18-65 year) were randomly recruited from patients attending the nutrition clinics of Mashhad, Iran. Participants were divided into three groups according to body mass index (BMI) (healthy-weight, overweight, and obese) and WC categories (not at risk, increased risk, and substantially increased risk). Plasma levels of omega-3 fatty acids were analyzed in blood sample of all participants by gas chromatography apparatus equipped with a flame ionization detector (GC-FID). The protocol was approved by the Ethics Committee of the Mashhad University of Medical Science (MUMS) and written informed consent was obtained from all individuals. Alpha-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were inverse association with increasing both overall (p<0.001, p Plasma omega-3 polyunsaturated free fatty acids were inversely in relation with anthropometric measures of obesity including BMI and WC. Further studies are needed to identify the possible mechanism(s) that links plasma omega-3 fatty acids with overall and abdominal obesity.

Hypertriglyceridemia is a common form of dyslipidemia and is associated with several comorbidities, such as increased risk of pancreatitis and cardiovascular diseases (CVD). The white blood cell (WBC) count is a non-specific inflammatory marker associated with a wide variety of diseases such as diabetes, hypertension, and atherosclerotic cardiovascular disease. The objective of this study was to perform a gender-stratified examination of the association between hypertriglyceridemia and hematological parameters in a large sample of Iranian population. The triglyceride (TG) levels and hematological parameters were measured in 9,780 participants (40% males and 60% females) aged 35-65 years, enrolled in a population-based cohort (MASHAD) study in northeastern Iran. Participants were stratified into three groups based on the definition of hypertriglyceridemia: TG<150 mg/dl (n=6521), TG=150-199 mg/dl (n=1597), and TG≥200 mg/dl (n=1662). A complete blood count (CBC) was obtained for all the subjects. The mean WBC count increased with increasing severity of hypertriglyceridemia among both men and women. Participants with high and very high TG levels had significantly higher WBC count, RBC count, platelet count, hemoglobin, hematocrit, and mean corpuscular hemoglobin concentration and significantly lower RDW. After performing multivariate logistic regression, WBC count and RDW were independently related to hypertriglyceridemia. In conclusion, hypertriglyceridemia is associated with elevated WBC count which may partly explain the observed association between hypertriglyceridemia and CVD.

Disease related malnutrition (DRM) has been an important problem in all health care settings for many years and is associated with an increased risk of adverse clinical outcomes. Nutritional interventions with ONS are associated with fewer numbers of hospital admissions and shorter duration of hospital stay. The objective of the present study was to investigate the knowledge and attitude of medical specialists regarding ONS prescribing practices. A total sample of 120 medical specialists were recruited from two hospitals in northeastern Iran. Sixty medical specialists from Imam Reza Hospital and sixty medical specialists from Ghaem Hospital were randomly selected. A questionnaire was administered by face-to-face interview to each participant. Only a small number of medical specialists reported the use of screening tools to ascertain whether a patient requires ONS. Both medical specialists in Imam Reza (44%) and Ghaem (36.8%) hospitals reported increased prescription of ONS in recent years. Only 38.5% of the medical specialists said that they would monitor the patient after prescribing ONS. Only 32.9% of medical specialists stated that they have received training on use of ONS in the past. Around 41% of medical specialists stated that they have no idea about the calorie content of a standard 200 mL carton of ONS. The results of the present study raise concerns regarding the appropriateness of current ONS transcriptions among hospitalized patients. Therefore, there is a need for targeted educational interventions for medical specialists in order to promote the use of ONS in hospitalized patients.

Water is a valuable and irreplaceable element for the socio-economic development of countries. It is also the most important factor for the equilibrium of the ecosystem and environment. Todays, several factors cause water problems and related issues around the world. Governments and nations are always looking for the correct understanding of water issues and providing sustainable solutions to solve these problems. This attitude causes governments, institutions and water authorities to get together in international meetings. Hence, international festivals are held around the world in order to enhance solutions to water problems, make a global dialogue and take advantage of collective wisdom to resolve water related issues. In most of these events, some prizes are awarded to those who have made outstanding contributions in the field of water problems. The purpose of this paper is to review the most important international events in this regard and introduce effective criteria for achieving international water awards.