m.h. ahmadi

Graphene oxide is considered as a new type of membrane material. However, it suffers from a low steady-state filtration flux as well as unstable performance, which limits its practical applications. For this reason, the aim of this study was to combine GO with layered double hydroxides (LDH), with bilayer hydrophilic transport channels and positively charged surface in different weight ratios (i.e. 5:1, 3:1, 1:1, 1:3, and 1:5) is The optimized GO-Mg/Al/Zn-LDH was then combined with chitosan (CS) and coated on stainless steel mesh (mesh) to obtain a membrane with high stable flux that is hydrophilic and superoleophobic under water. The layer-by-layer (LBL) hybrid network morphology was fully characterized and investigated for the removal of heavy crude oil from water surfaces, with a separation efficiency higher than 99.5% (ɳ%) and a water flux of Lm-2.h-1 It showed 160222 ± 102 under the force of gravity. In addition, the exceptional mechanical/chemical stability, effective separation, high water flux, reusability and excellent superhydrophilicity, LBL hybrid mesh can be considered as a promising renewable membrane for the treatment of oily water (water containing oil droplets).

Calibration of hot-wire and hot-film probes at low velocities is a difficult task because the dynamic pressure at these velocities is very low and may not be measured easily. To overcome this problem, substituent techniques have been presented in the literature that rely on other phenomena and utilize different hardware. This paper describes a simple and low-cost method which proposes to move the anemometer probe in quiescent air (here by means of a swinging arm) and track this motion with a camera. After processing of the images, velocity time history of the probe is found by numerical calculations. Calibration curve is then obtained without any predetermined relationship. Using a medium-speed video camera that is often found in laboratories would avoid the need to a position sensor and a complicated arm on which this sensor is mounted. This technique can be used not only for pendulums but also for other means of moving probes in quiescent medium.

In this study, the acid-base neutralization reaction of acetic acid and ammonium hydroxide reaction inside a mixing tank to study the mixing interaction and chemical reaction by using simultaneous planar laser-induced fluorescence (PLIF)1 and particle image velocimetry (PIV)2 methods has been examined. The blade rotation speed, the blade distance from the bottom of the tank, the presence of buffers and the rheological properties of the fluid inside the tank are all the parameters that can be changed and optimized to improve the conditions of performance of mixed tanks which they are investigated to test them effects. The results showed that the progress of the acid-base neutralization reaction in the studied conditions was under the control of the mixing conditions of the reactants. To investigate the effect of blade distance from the tank floor, the ratios C/T = 0.25, C/T = 0.5 and C/T = 0.75 were selected which C is the distance of the blade from the tank floor and T is the diameter of the tank. Also the experiments were repeated at three speeds of 100 rpm, 150rpm and 200rpm. The results showed that by increasing the distance of the blade from the bottom of the tank, which is equivalent to increasing the C/T ratio, the reaction time was significantly reduced. In addition, at constant C/T ratios, the reaction time decreases sharply by increasing blade rotation speed. Also, in order to investigate the effect of the number of buffles in the tank, a buffleless, 2 buffles and 4 buffles blades were used at speeds of 100 rpm, 150rpm and 200rpm. Based on the results, it was found that as the number of buffles in the tank increased, the reaction time decreased. Also, a comparison of experiments performed in each tanks with three different speeds showed that the time-reduction ratios in tanks with fixed number of buffles at different speeds have a similar downward trend. Another parameter studied in this study was fluid viscosity, which was tested in µ= 35 mPa.s, µ=55 mPa.s, µ=75 mPa.s. The results of these experiments showed that with increasing fluid viscosity from µ=35 mPa.s to µ=55 mPa.s, the reaction time increased significantly, However, increasing the fluid viscosity by µ=75 mPa.s has less effect on the reaction time.

One of the important aspects of substance abuse is the risk factors in the onset of drug use. Undoubtedly, many factors can be identified and strengthened as protective factors against drug abuse. This study aimed to determine the relationships between religiosity, self-esteem, resiliency, and addiction acknowledgment in adolescents. The study population consisted of all adolescent boys in the city of Qazvin. Data are from 347 respondents aged 14–18 years in the Qazvin’s high schools which were selected through multi-stage cluster sampling method. Respondents completed questionnaires including Khodayarifard religion, Connor-Davidson Resilience scale, Coopersmith's self-esteem and addiction acknowledgment. Correlation and regression methods were used for the data analysis. The results showed, there was a significant negative correlation between religiosity, self-esteem and resiliency with potential for addiction acknowledgment. Overall, these variables explained 54.0% of the variance in addiction acknowledgment. Therefore, it can be concluded that strengthening religiosity, self-esteem and resiliency in adolescents could prevent them from addiction acknowledgment.