Liquid paraffin as a coolant fluid can be applied in electronic devices as a result to its suitable capabilities such as electrical insulating, high heat capacity, chemical and thermal stability, and high boiling point. However, the poor thermal conductivity of paraffin has been confined its thermal cooling application. Addition of high conductor nanoparticles to paraffin can fix this drawback properly. In this article, the influence of the nanoparticles on the thermal conductivity of base material was assessed. Temperature (20-50° C) and volume fractions (0-3%) effect on the thermal conductivity of paraffin/alumina nanofluids have been considered. Nanofluid samples were prepared applying the two-step method. The thermal conductivity was measured by a KD2 pro instrument. The results indicated the thermal conductivity augments smoothly with an increase in volume fraction of nanoparticles as well as temperature. Moreover, it observed that for nanofluids with more volume-fraction the temperature affection is more remarkable. Thermal conductivity enhancement (TCE) and effective thermal conductivity (ETC) of the nanofluid was calculated and new correlations were reported to predict the values of them based on the volume fraction of nanoparticles and temperature of nanofluid accurately.

The thermal balance analysis is a useful method to determine energy distribution and efficiency of internal combustion (IC) engines. In engines cooling concepts, estimation of heat transfer to brake power ratio, as one of the most significant performance characteristics, is highly demanded. In this paper, investigation of energy balance and derivation of specific heat rejection is carried out Experimentally and numerically. Experiments are carried out on an air-cooled, single cylinder, four-stroke gasoline IC engine. The engine is simulated numerically and after validation with Experimental data, the code is run to find out total and instantaneous thermal balance of engine. Results indicate that about onethird of fuel energy is converted to brake power and major part of energy is dissipated through exhaust and heat transfer. Experimental and numerical results show that by increasing engine speed, heat transfer to brake power ratio decreases. It is also observed that increasing engine speed leads to increase of exhaust power to brake power ratio. Finally two correlations for estimation of heat transfer and exhaust power to brake power ratios are obtained.

Currently, composite structures have many applications in various industries including aerospace, automotive, marine, and petrochemicals. In most of these applications, the structure is under dynamic and static loads and it can cause buckling, vibration, and fatigue. Therefore, the static and dynamic analysis of these structures is essential in order to understand their characteristics, including buckling, natural frequency, and the shape of vibrating modes. One of the most important non-destructive methods for predicting the buckling load of the structure is the vibrational correlation technique (VCT), which is based on frequency variations with the axial load. In this study, an Experimental study of the buckling load of composite sandwich plates with lozenge core has been investigated. The hand lay-up method has been used for fabrication of the composite sandwich plates. One of the specimens was used for the modal test. In order to verify the results of the VCT, the buckling load of four specimens was calculated by the Experimental buckling test. The error of VCT was 2. 1 %. Hence, the efficiency of the VCT for composite sandwich plates with lattice core was confirmed. Also, by investigating the effect of applied load percentage on the accuracy of the VCT, it was found that for the applied load of more than 63% of the buckling load, the accuracy of prediction of the vibrational correlation technique is acceptable.

Introduction: In Iran, thousands of young individuals become victims of head injury annually. Head injury can damage neuronal cells which may in turn complicate the recovery of the patients. Also, the increase of iron in cerebrospinal fluid (CSF) following head injury may contribute to the hypoxic-ischemia brain damage by catalyzing the formation of free radicals (Harber-Weiss Rection). The object was to study the correlation between the level of iron in CSF with cerebral tissue damage after Experimental head injury in adult male rats.Methods: A total of 27 Wistar rats were randomly divided into 3 groups of control (n=7), experimemal I (n=9), and Experimental II (n=II). Head injury was induced with a 300g weight dropped on the skull from a distance of 1 meter. CSF samples were withdrawn from controls with insertion of a Hamilton needle through atlanto-ocipital (OA) membrane. Also, CSFs were collected from Experimental animals I and n at 30 min and 60 min after induction of head injury, respectively. All CSF samples were measured with Atomic Absorption Spectrometry. Also, biopsy samples from parietal lobe of brain were fixed in 10% formalin and stained with Hemotoxyl in-Eosin for morphological evaluation.Results: The level of iron in CSF of control group was 2.95±31 ppm. The level of iron in experimetanl groups of I and II increased to 6.14±1.01 (P>0.05) and 14.72±2.94 (P<0.001), respectively. The cerebral tissue of group I consisted of abnormal dark neurons which were scattered among normal neurons. However, the majority of neuronal cells were damaged in Experimental group n.Conclusion: The results showed that the level of iron in CSF as well as neuronal cell architecture was time dependent after Experimental head injury. This may cause a non-reversible brain injury with release of free radicals in CSF following head injury.

The purpose of this research is to develop relationships to predict the results of measuring the electrical resistivity of the standard test method ASTM C1760 with assistance of other methods’ results. Comparative Methods in this paper are Impedance spectroscopy method, one electrode method and four electrode method. Impedance spectroscopy method is the most common in laboratory studies, ASTM C1760 method (Standard Test Method for Bulk Electrical Conductivity of Hardened Concrete) only has a standard rule and use in laboratory, one electrode method is a new technique in field and it’s application is in the reinforcement structures, and four electrode measurements are more common in field. In laboratory methods, bulk electrical resisitivity measured but in field, usually surface electrical resisitivty evaluated, that is why several source of errors affecting on the results of this test methods. To reach the aim of this research, 49 mix designs with a vast domination of electrical resistivity from about 40 (W-m) to 290 (W-m) was intended and for each of mix designs, 4 cylindrical and one reinforced slab specimen were made. reinforced slab specimen for one electrode measurement and cylindrical specimens for the other test method measurments were considered. Moreover, the electrical resistance of the aforementioned methods was measured at 28 days age. The results showed that there is a negligible difference between the results of impedance spectroscopy and ASTM C1760 methods; however, the electrical resistivity measured by ASTM C1760 method was slightly higher than the results of impedance spectroscopy method in the concrete. As a result, we can use the results of the impedance spectroscopy method instead of standard test method results in the lack of facilities with accepting about 5% of error. In the four electrode method, a number of factors including the imbalance among the distances between electrodes and structure dimensions can result systematic errors. That is why the measurements’ results with the method is approximately 140% larger than the standard test method results. Due to the lack of a comprehensive relationship for calculating the cell constant in the one electrode method, the value of this constant was obtained by comparing the results of the standard test method. After that, the electrical resistivity values were calculated. Electrical resistivity measurement results which was obtained by this method had also little difference with the standard test method results. Finally 3 relationships separately developed for predicting the result of standard test method from results of the each other test methods. Since the features and conditions of measuring by the standard test method are not available in the entire projects, the current results are capable to predict the standard method’s results with assistance of other methods’ results.

Background: This study was conducted to investigate the effect of a four- week aerobic physical activity in water on the extent of clinical improvement and amount of neuregulin-1 (NRG1) protein in the brain tissue of animal model of multiple sclerosis (MS) via inducing Experimental autoimmune encephalomyelitis (EAE).Methods: To this end, a total number of 80 female Syrian mice from the race of C57BL/6, aging 10 to 12 weeks and weighing 20±2 gram were divided into eight groups of 10, namely, control, swimming, MS, MS + swimming, MS + interferon beta (INF-b), MS + solvent, and MS + solvent + swimming environment. For induction of EAE, 300 mg (35-55) myelin oligodendrocyte glycoprotein (MOG) was first mixed in 100 ml phosphate buffered saline (PBS) with complete Freund's adjuvant (CFA) and injected subcutaneously (SC). At the time of injection and after 48 hours, 300 ng pertussis toxin was diluted in PBS and injected intraperitoneally (IP). During a week after the treatment, mice recieving the drug in form of intraperitoneal received 150 IU/g of the drug per day. Clinical symptoms and the mice's weights were recorded every day. Physical activity group did the aerobic activities for four weeks, five sessions a week, 30 minutes each session. Standard scoring system was used for clinical check and enzyme- linked immunosorbent assay (ELISA) was applied to measure NRG1 protein. Data analysis was done using one- way ANOVA.Findings: The effect of physical activity in water on treatment of multiple sclerosis was the same as that of interferon. The amount of rise in NRG1 protein in swimming group was more than that of the interferon group.Conclusion: Aerobic swimming exercises could probably help remyelination by increasing the amount of NRG1 protein and lowering the speed of myelin destruction, hence, helping the clinical improvement in patients with multiple sclerosis.

Liquid paraffin can be used as a coolant fluid in electronic and cutting devices due to its suitable capabilities such as electrical insulating, high heat capacity, chemical, and thermal stability, and high boiling point. In this study, the dynamic viscosity of paraffin containing the alumina nanoparticles has been examined Experimentally. The nano􀏔 luids with different composition of alumina (0, 1, 2, and 3%) with the diameter of 20 nm were prepared by two‐ step method and tested by professional Brookfield rheometer in the temperature range of 20 oC to 60 oC and the shear rates of 12 s‐ 1 up to 200 s‐ 1. Experimental results indicated that the nano‐ lubricant behaves as Newtonian 􀏔 luid in the volume fraction of 0 and 1% only at the temperatures of 50 and 60 oC. While it behaves as non‐ Newtonian 􀏔 luid in the volume fraction of 2 and 3% for all measured temperatures. The results showed that the power law model represents the best curve fitting of the Experimental data. Therefore, the coefficient values of power‐ law model including, consistency index and flow index were reported. Finally, an equation of relative viscosity based on the volume fraction and temperature of the combination was proposed by applying the curve fit technique on the Experimental data.