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Hassan Yassin A.,Gutierrez-Torres C.C. Korean Nuclear Society 2006 Nuclear Engineering and Technology Vol.38 No.8
Injection of microbubbles within the turbulent boundary layer has been investigated for several years as a method to achieve drag reduction. However, the physical mechanism of this phenomenon is not yet fully understood. Experiments in a channel flow for single phase (water) and two phase (water and microbubbles) flows with various void fraction values are studied for a Reynolds number of 5128 based on the half height of the channel and bulk velocity. The state-of-the art Particle Tracking Velocimetry (PTV) measurement technique is used to measure the instantaneous full-field velocity components. Comparisons between turbulent statistical quantities with various values of local void fraction are presented to elucidate the influence of the microbubbles presence within the boundary layer. A decrease in the Reynolds stress distribution and turbulence production is obtained with the increase of microbubble concentration. The results obtained indicate a decorrelation of the streamwise and normal fluctuating velocities when microbubbles are injected within the boundary layer.
Ghareeb Doaa A.,Saleh Samar R.,Seadawy Mohamed G.,Nofal Mohammed S.,Abdulmalek Shaymaa A.,Hassan Salma. F.,Khedr Shaimaa M.,AbdElwahab Miral G.,Sobhy Ahmed A.,Abdel-Hamid Ali saber Ali,Yassin Abdelrah 한국약제학회 2021 Journal of Pharmaceutical Investigation Vol.51 No.6
Purpose A novel coronavirus (COVID-19) that has not been previously identified in humans and has no specific treatment has recently spread. Treatment trials using antiviral and immune-modulating drugs such as hydroxychloroquine (HCQ) were used to control this viral outbreak however several side effects have emerged. Berberine (BER) is an alkaloid that has been reported to reveal some pharmacological properties including antioxidant and antimicrobial activities. Additionally, Zinc oxide nanoparticles (ZnO-NPs) possess potent antioxidant and anti-inflammatory properties. Therefore, this study was undertaken to estimate the efficiency of both BER and synthetic ZnO/BER complex as an anti-COVID-19 therapy. Methods First, the ZnO/BER complex was prepared by the facile mixing method. Then in vitro studies on the two compounds were conducted including VeroE6 toxicity, anti-COVID-19 activity, determination of inhibitory activity towards papain-like proteinase (PL pro) and spike protein- and receptor- binding domain (RBD) as well as assessment of drug toxicity on RBCs. Results The results showed that ZnO/BER complex acts as an anti-COVID-19 by inhibiting spike protein binding with angiotensin-converting enzyme II (ACE II), PL pro activity, spike protein and E protein levels, and expression of both E-gene and RNA dependent RNA polymerase (RdRp) at a concentration lower than that of BER or ZnO-NPs alone. Furthermore, ZnO/BER complex had antioxidant and antimicrobial properties where it prevents the auto oxidation of 2,2-Diphenyl- 1-picrylhydrazyl (DPPH) and the culture of lower respiratory system bacteria that affected Covid 19 patients. The ZnO/BER complex prevented as well the HCQ cytotoxic effect on both RBC and WBC (in vitro) and hepatotoxicity, nephrotoxicity and anemia that occurred after HCQ long administration in vivo. Conclusion The ZnO/BER complex can be accounted as promising anti-COVID 19 candidate because it inhibited the virus entry, replication, and assembly. Furthermore, it could be used to treat a second bacterial infection that took place in hospitalized COVID 19 patients. Moreover, ZnO/BER complex was found to eliminate the toxicity of long-term administration of HCQ in vivo.
Iqbal M. Ismail,Ahmad S. Summan,Jalal M. Basahi,Essam Hammam,Mohamed F. Yassin,Ibrahim A. Hassan 한국대기환경학회 2021 Asian Journal of Atmospheric Environment (AJAE) Vol.15 No.2
Concentrations of black carbon (BC), organic carbon (OC), and total suspended particulate matter (TSP) were simultaneously assessed in urban, rural and residential areas in Jeddah city for one year from January to December 2017. It was aimed in the present study to provide information about the spatial and seasonal variability of these aerosol species in Jeddah, and insight into sources, processes and effects of meteorological conditions. To the best of our knowledge, this is the first study investigating the variability of carbonaceous aerosols (OC and BC) in Saudi Arabia. The average concentrations of OC, BC, and TSP varied spatially and temporally. The annual average concentrations of OC, BC, and TSP were 134.05, 7.16, and 569.41 μg m-3 and 34.32, 5.14, and 240.64 μg m-3 and 10.67, 4.39 and 101.31 μg m-3 in the urban, residential and rural areas, respectively. Moreover, there was a clear seasonal variation in the concentration of carbonaceous aerosols; the highest concentrations were recorded in February and September, while the lowest concentrations of OC were recorded during April, May and August in the urban, residential and rural sites, respectively. Nevertheless, the lowest concentrations of BC were recorded during March in the urban and residential sites and during November in the rural site. The relative concentrations of OC and BC to the TSP were relatively high, and they have a significant correlation with prevalent wind speed (-0.636, and -0.581 in the urban area), (-0.539 and -0.511 in the residential area), and (-0.508 and -0.501 in the rural area), respectively. The marked differences in the concentrations of BC and OC were reflected on OC/BC ratio, which is a good representative of different source types. This preliminary study showed that the potential local sources were emissions from traffic (fossil fuel), biomass burning, anthropogenic activities (e.g. car drifting and outdoor cooking), and industrial activities. The present study suggest the presence of highly inefficient combustion sources and highlight the need for the regulation of such emissions.
Sena Marcos S.,Hassan Yassin A. 한국원자력학회 2023 Nuclear Engineering and Technology Vol.55 No.9
The scaled water-cooled Reactor Cavity Cooling System (RCCS) experimental facility reproduces a passive safety feature to be implemented in Generation IV nuclear reactors. It keeps the reactor cavity and other internal structures in operational conditions by removing heat leakage from the reactor pressure vessel. The present work uses Flownex one-dimensional thermal-fluid code to model the facility and predict the experimental thermal-hydraulic behavior. Two representative steady-state cases defined by the bulk volumetric flow rate are simulated (Re ¼ 2,409 and Re ¼ 11,524). Results of the cavity outlet temperature, risers' temperature profile, and volumetric flow split in the cooling panel are also compared with the experimental data and RELAP system code simulations. The comparisons are in reasonable agreement with the previous studies, demonstrating the ability of Flownex to simulate the RCCS behavior. It is found that the low Re case of 2,409, temperature and flow split are evenly distributed across the risers. On the contrary, there's an asymmetry trend in both temperature and flow split distributions for the high Re case of 11,524.