Cobalt/Chromium Nanoparticles-Incorporated Carbon Nanofibers as Effective Nonprecious Catalyst for Methanol Electrooxidation in Alkaline Medium

Ibrahim M. A. Mohamed,Moaaed Motlak,H. Fouad,나지르 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.5

Cobalt-Chrome nanoparticles-incorporated carbon nanofibers (CNFs) are proposed as an effective nonprecious electrocatalyst for methanol oxidation in the alkaline media. The introduced nanofibers were prepared by simple technique, electrospinning. Carbonization of as-spun mat composed of chromium acetate, cobalt acetate and poly(vinyl alcohol) (PVA) at high temperature (900℃) leads to production of the introduced nanofibers. The physicochemical characteristics were investigated by X-ray diffractometer (XRD), scanning electron microscope (SEM), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM) equipped with EDX and TEM mapping. The exploited analyses confirmed that the final product is in the form of CNFs decorated by Co/Cr nanoparticles. Based on the results obtained from the cyclic voltammetry (CV) measurements, the proposed Co/Cr-incorporated CNFs possess high electrocatalytic activity toward methanol electrooxidation as a clear peak of methanol oxidation appeared with corresponding current density of 56 mA/cm2 . Moreover, the current density increased by increasing methanol concentration up to 4.0 M. Overall, the proposed nanofibers open new avenue for platinum-free and stable nanostructural catalysts for fuel cell technology.

First Measurements of Carbonaceous Aerosol across Urban, Rural and Residential Areas in Jeddah City, Saudi Arabia

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.

Nematicidal Compounds from the Leaves of Schinus terebinthifolius Against Root-knot Nematode, Meloidogyne incognita Infecting Tomato

Fatma M. Abdel Bar,Dina S. Ibrahim,Sahar R. Gedara,Mohammed S. Abdel-Raziq,Ahmed M. Zaghloul 한국생약학회 2018 Natural Product Sciences Vol.24 No.4

The root-knot nematode, Meloidogyne incognita caused a serious damage to many plants. The phenolic components of the leaves of Schinus terebinthifolius were investigated as potential nematicidal agents for M. incognita. Nine compounds were isolated and characterized as viz., 1,2,3,4,6-pentagalloyl glucose (1), kaempferol-3-O-a-L-rhamnoside (Afzelin) (2), quercetin-3-O-a-L-rhamnoside (Quercetrin) (3), myricetin (4), myricetin-3-O-a-L-rhamnoside (Myricetrin) (5), methylgallate (6), protocatechuic acid (7), quercetin (8), and gallic acid (9) using nuclear magnetic resonance (NMR) spectroscopy. Compound 1 showed pronounced nematicidal activity compared to Oxamyl as a positive control. It showed the lowest eggs-hatchability (34%) and the highest mortality in nematode population (21% after 72 hours of treatment) at a concentration of 200 mg/mL. It exhibited the best suppressed total nematode population, root galling and number of eggmasses in infected tomato plants. The total carbohydrates and proteins were also significantly induced by 1 with reduction in total phenolics and increase in defense-related proteins. Thus, compound 1 could be a promising, more safe and effective natural nematicidal agent for the control of root-knot nematodes.

Environmentally benign Scouring of Cotton Knits Using Locally Produced Acid Pectinase Enzyme

Nabil A. Ibrahim,Basma M. Eid,Mohamed S. Abdel Aziz,Soha M. Hamdy,Safaa E. AbdAllah 한국섬유공학회 2019 Fibers and polymers Vol.20 No.4

The main task of the present study is to pre-screen selected fungal strain (Fusarium oxysporum M1-EGY) isolatedfrom local agriculture soil and optimize cultivation conditions for an acid pectinase production. Experimental resultsdemonstrated the optimum conditions for achieving the highest enzyme activity (14.80 U/ml) were found to be: incubationperiod (8 days) at pH (5), temperature (30 oC), and shaking rate (150 rpm), apple pectin carbon source (2 %), and ammoniumphosphate as nitrogen source (0.2 gN/l). The positive impacts of utilizing the produced crude acid-pectinase in eco-friendlyscouring of various cotton knits as well as their subsequent bleaching and reactive dyeing have been confirmed. Additionally,the use of local resources for an acid pectinase production would encourage and promote local production of textile enzymesand their potential applications in Egyptian textile sector, taking in consideration efficiency, textile quality, environmental andeconomy concerns.

Physicochemical and photo-electrochemical characterization of novel N-doped nanocomposite ZrO₂/TiO₂ photoanode towards technology of dye-sensitized solar cells

Mohamed, Ibrahim M.A.,Dao, Van-Duong,Yasin, Ahmed S.,Mousa, Hamouda M.,Yassin, Mohamed A.,Khan, Muhammad Yasir,Choi, Ho-Suk,Barakat, Nasser A.M. Elsevier 2017 Materials characterization Vol.127 No.-

<P><B>Abstract</B></P> <P>This work introduces the synthesis of N-doped nanocomposite of ZrO<SUB>2</SUB>/TiO<SUB>2</SUB> nanofibers (NFs) by use of both electrospinning and hydrothermal methods. The physicochemical properties of the introduced TiO<SUB>2</SUB> NFs are investigated to describe the morphology, crystallinity and chemistry through FESEM, SEM-EDX, XRD, TEM and XPS. As the results, the investigated material can be described as N@ZrO<SUB>2</SUB>/TiO<SUB>2</SUB> NFs. The crystal structure of the prepared TiO<SUB>2</SUB> is only anatase structure. Then, the novel NFs are utilized to design novel photoanode and photo-electrochemical characterization such as current-potential response under light, incident photon-to-current efficiency (IPCE) and electrochemical impedance spectroscopy (EIS) of the dye-sensitized solar cell (DSC) are also investigated. The photovoltaic response showed that the efficiency of the DSCs employed N@ZrO<SUB>2</SUB>/TiO<SUB>2</SUB> photoanode gave 4.95%, which was higher than those of DSCs designed with ZrO<SUB>2</SUB>/TiO<SUB>2</SUB> NFs (4.51%) and N@TiO<SUB>2</SUB> NFs (4.41%) photoanodes. The high photo-response of DSC by use of N@ZrO<SUB>2</SUB>/TiO<SUB>2</SUB> NFs can be attributed to enhanced electrical conductivity, which is studied via EIS, and presence of active sites of N. These active sites can easily absorb dye-molecules in the step of dye-loading in the fabrication of DSC.</P> <P><B>Highlights</B></P> <P> <UL> <LI> N-doped ZrO<SUB>2</SUB>/TiO<SUB>2</SUB> nanofibers (NFs) are synthesized via facile two steps; electrospinning followed by hydrothermal. </LI> <LI> The produced NFs have only anatase crystal structure. </LI> <LI> 4.95% PV efficiency was achieved by the synthesized NFs. </LI> <LI> DSC based on N-doped ZrO<SUB>2</SUB>/TiO<SUB>2</SUB> NFs shows high electrical conductivity and low charge transfer resistance; 9.375Ω. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Flow Downstream Sluice Gate with Orifice

Ibrahim M. Mohamed,Fahmy S. Abdelhaleem 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.12

Gates and orifices were significant common structures used in controlling and adjusting the flow in water system channels. Installing of an orifice with sluice gates, increase the flow discharge with minimizing the horizontal jets under gate that was attributed with higher bed flow velocity and larger scour geometry downstream these gates. An experimental study was conducted to examine the flow pattern and the bed configurations downstream sluice gates with an orifice. In this research, a circular orifice employed with sluice gates as a means of energy dissipation downstream the gates, was explored. Forty-five runs were completed under 3 discharges, 3 upstream water heads, and 7 tail gate water depths. Five models for sluice gate with orifice were utilized. A series of regime plots were created to help designing the sluice gate with orifice as heading up and flow distributions structures. The outcomes illustrated that combining of an orifice with sluice gates productively scattered the jump energy and diminished the downstream local scour compared to the conventional sluice gate. Additionally,existed equations used to predict the jump length downstream sluice gate were applicable in case of sluice gate with orifice provided similar flow conditions were achieved. The optimum ratio of orifice and under gate areas was also introduced.

Improving the brittle behavior of high-strength shielding concrete blended with lead oxide, bismuth oxide, and tungsten oxide nanoparticles against gamma ray

Mohamed Amin,Ahmad A. Hakamy,Abdullah M. Zeyad,Bassam A. Tayeh,Ibrahim Saad Agwa 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.85 No.1

High-strength shielding concrete against gamma radiation is a priority for many medical and industrial facilities. This paper aimed to investigate the gamma-ray shielding properties of high-strength hematite concrete mixed with silica fume (SF) with nanoparticles of lead dioxide (PbO2), tungsten oxide (WO3), and bismuth oxide (Bi2O3). The effect of mixing steel fibres with the aforementioned binders was also investigated. The reference mixture was prepared for high-strength concrete (HSCC) containing 100% hematite coarse and fine aggregate. Thirteen mixtures containing 5% SF and nanoparticles of PbO2, WO3, and Bi2O3 (2%, 5%, and 7% of the cement mass, respectively) were prepared. Steel fibres were added at a volume ratio of 0.28% of the volume of concrete with 5% of nanoparticles. The slump test was conducted to workability of fresh concrete Unit weight water permeability, compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity tests were conducted to assess concrete’s engineering properties at 28 days. Gamma-ray radiation of 137Cs emits photons with an energy of 662 keV, and that of 60Co emits two photons with energies of 1173 and 1332 keV were applied on concrete specimens to assess radiation shielding properties. Nanoparticles partially replacing cement reduced slump in workability of fresh concrete. The compressive strength of mixtures, including nanoparticles was shown to be greater, achieving 94.5 MPa for the mixture consisting of 7.5 PbO2. In contrast, the mixture (5PbO2-F) containing steel fibres achieved the highest values for splitting tensile, flexural strength, and modulus of elasticity (11.71, 15.97, and 42,840 MPa, respectively). High-strength shielded concrete (7.5PbO2) showed the best radiation protection. It also showed the minimum concrete thickness required to prevent the transmission of radiation.

Effect of high temperatures on mechanical, radiation attenuation and microstructure properties of heavyweight geopolymer concrete

Mohamed Amin,Abdullah M. Zeyad,Bassam A. Tayeh,Ibrahim Saad Agwa 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.80 No.2

Heavyweight geopolymer concrete (HWGC) is a new concrete type that combines the benefits of geopolymer concrete (GC) and heavyweight concrete. HWGC can be used to produce particular properties such as high radiation shielding, and mass concrete elements. HWGC based on fly ash and ground granulated blast furnace slag, using electric arc furnace steel slag (EAFSS), barite and ilmenite coarse aggregates can substantially have higher specific gravities than concrete made with crushed dolomite. In the experimental work carried out on four main groups, 13 GC mixes are prepared by using heavyweight coarse aggregates (HWCAs) at volume ratios of 0%, 25%, 50%, 75% and 100%. Fresh and mechanical properties, compressive and tensile strengths, and influence of high temperature on radiation are investigated for specimens subjected to high temperatures of up to 900°C for 1, 2 and 3 hours. Moreover, the internal structure of geopolymer is analyzed using scanning electron microscope and energy-dispersive X-ray. Results show a good effect of HWCAs on the properties, radiation shielding and unit weight. The density of heavyweight geopolymer mixes ranges between 2,415 and 3,480 kg/m3, and HWCA ratios contribute to an increase in all properties of GC mixtures using up to 75% of NWCAs. Heavier coarse aggregate of ilmenite dampens the effect of higher temperatures on GC strength compared with lighter aggregates. In addition, replacing crushed dolomite with heavyweight aggregates of EAFSS, barite and ilmenite increases the attenuation rate to 27%, 21% and 13%, respectively. This finding confirms that the type of aggregate used in the production of GC is important for reducing the permeability of X-ray.

A comparative study of mechanical behavior of ABS material based on UVC sterilization for medical usage

Mohamed A. Aboamer,Doaa H. Elgohary,Ali Abdullah Almukil,Ahmed A. Aboamer,Ibrahim M Alarifi,Mohsen Bakouri,Nader A. Rahman Mohamed 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.7

This study aims to examine the mechanical properties of acrylonitrile butadiene styrene specimens using ASTM 638, 695, and 790. UVC radiation was also used as a sterilizing method. The fused deposition modeling of 3D-printed polymerize with 30 % filling was used to manufacture 30 specimens for tensile, compression, and bending. Half of the specimens were treated with UVC, whereas the other half were not. The chosen dosage of 13.5 J/cm 2 with an exposure time of 48 min corresponds to 3650 sterilization treatments or 10 years of sterilization. The average ultimate stress in the tensile test, compression test, and bending test was 34.5 ± 7.4, 25.4 ± 0.5, and 24.5 ± 2.1 Mpa, respectively. The analysis of variance test shows that UVC radiation has a demonstrable influence on tensile specimens, with a P-value of 0.012, which is less than the significance threshold of 0.05. Thus, the null hypothesis is rejected.

Liberalizing Maritime Transport Services: Towards a Fair Liberalization

( Mohamed M. Ali Ibrahim ) 한국해운물류학회(구 한국해운학회) 2003 해운물류연구 Vol.39 No.-

The maritime transport sector is considered as the most liberalized sector due to its international nature, but this fact does not imply that the sector is completely free because still many restrictions are found, some of them imposed by developed countries and - as a reaction - others are imposed by developing countries. The restriction imposed by advanced countries are: barriers to enter into the industry, international cartels, alliances, conferences, restrictions on maritime labour movements and stiff shipping registration conditions. As a reaction, developing countries try to find a way to survive in maritime transport service market through: cargo reservation systems using bilateral agreements. Code of Conduct, subsidization of maritime transport sectors and restriction of the commercial presence in ports. It is worth mentioning that developed countries apply the same restriction practices used by developing countries; it is also noticed that liberalizing transport services negotiations neglect the restrictive practices imposed by developing countries whereas they concentrate on the restriction practices used by developing countries. This concentrate on the restriction practices used by developing countries. his paper aims at discussing the restrictive practices imposed by both developed and developing countries to liberalize maritime transport services on a fair basis.