Investigation of Polypyrrole Coatings Containing Nanosized Metal Oxides for Corrosion Protection of AA2024 Al Alloy

Fekri, F.,Shahidi, M.,Foroughi, M.M.,Kazemipour, M. The Korean Electrochemical Society 2019 Journal of electrochemical science and technology Vol.10 No.2

The corrosion protection of AA2024 PPy coated samples doping with nanosized metal oxides, including $TiO_2$ and $CeO_2$ nanoparticles and $Nd_2O_3$ nanorods, during exposure to the solutions of 0.1 M $H_2SO_4$ and 3.5% NaCl was evaluated by electrochemical impedance spectroscopy (EIS) and linear polarization resistance (LPR) techniques. The nanorods of $Nd_2O_3$ were synthesized by cathodic pulse electrochemical deposition technique. The barrier properties of the different PPy coatings containing nanosized metal oxides immersed in $H_2SO_4$ solution were ranked as follows: $Nd_2O_3$ > $TiO_2$ > $CeO_2$. Therefore, the $Nd_2O_3$ coating sample provided the highest corrosion protection at any time of immersion up to 72 hours after immersing in $H_2SO_4$ solution. On the other hand, the $CeO_2$ coating sample displayed the best anticorrosive properties among the other coating samples after immersion in NaCl solution up to 28 days. This is due to the inhibition effect of cerium ions on aluminum alloys at near-neutral solutions.

Improvement of oxidation resistance of graphite by aluminosilicate coating with aluminum metaphosphate interlayer

M. Fekri,K. Jafarzadeh,S. A. Khalife Soltani,Z. Valefi,H. Mazhari Abbasi 한국탄소학회 2023 Carbon Letters Vol.33 No.7

In this research, in order to increase the oxidation resistance of graphite, kaolin and alumina powder with different ratios (26A-74S, 49A-51S, 72A-28S) and slurry method were used to create an aluminosilicate coating on the graphite substrate. In order to reduce the difference in the coefficients of thermal expansion of graphite with aluminosilicate coating, aluminum metaphosphate coating as an interlayer was prepared on the surface of graphite by cathodic electrochemical treatment. The isothermal oxidation test of the samples was carried out in air at a temperature of 1250 °C for 1, 3 and 5 h. The microstructure, chemical composition, and phase components of the coating were, respectively, analyzed by scanning electron microscope equipped with an energy-dispersive spectrometer and X-ray diffraction. The results indicated that, by increasing the withdrawal speed of the samples in slurry method, the amount of changes in the weight of the samples has increased and therefore had a direct effect on oxidation. In addition, it was approved that, at high-temperature oxidation, AlPO4 glass phase forms on aluminum metaphosphate interlayer which retards graphite oxidation. Along with aluminum metaphosphate, aluminosilicate coating also produces a glass phase which fills and seals the voids on the surface which prevents the oxygen to reach the surface of graphite. The created double-layer coating including an interlayer of aluminum metaphosphate + slurry coating prepared with the ratio of 26A-74S as the optimal coating in this research was able to increase the oxidation resistance of graphite by 73% at a temperature of 1250 °C.

Graphene oxide-silver nanosheet-incorporated polyamide thin-film composite membranes for antifouling and antibacterial action against Escherichia coli and bovine serum albumin

Fekri Abdulraqeb Ahmed Ali,Javed Alam,Arun Kumar Shukla,Mansour Alhoshan,Jamal M. Khaled,Waheed A. Al-Masry,Naiyaf S. Alharbi,Manawwer Alam 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-

Biofouling leads to degradation of membrane performance characteristics, including permeability,selectivity, and long-term stability. In this study, silver-doped graphene oxide (GO) was employed as ananoadditive to enhance the biofouling resistance of thin-film nanocomposite (TFN) membranes viainterfacial polymerization. Ag functionalization on GO sheets was carried out by a reduction reaction. Electron microscopy, Raman spectroscopy, and X-ray diffraction analyses were conducted to evaluate Agattachment on GO. According to zeta potential and contact angle measurements as well as atomic forcemicroscopy results, GO-Ag-incorporated TFN membranes showed a high negative charge, hydrophilicity,and a smooth surface. Bovine serum albumin protein and Escherichia coli (E. coli) were used as modelfouling agents to demonstrate the antifouling characteristics of the membranes. The TFN membranecontaining 80 ppm of GO-Ag had a high waterflux recovery ratio (89%) and low irreversible resistance(10%) after hydraulic washing. The biofouling resistance of the membranes was further studied by acolony-counting method, while bacterial adhesion was analyzed by spinning disk confocal microscopeimaging. The TFN membrane prepared with 80 ppm GO-Ag reduced 86% of viable E. coli cells in bacterialsuspensions, with only slight bacterial adherence on the membrane surface.

Risk factors associated with the recent cholera outbreak in Yemen: a case-control study

Fekri Dureab,Albrecht Jahn,Johannes Krisam,Asma Dureab,Omer Zain,Sameh Al-Awlaqi,Olaf Mü,ller 한국역학회 2019 Epidemiology and Health Vol.41 No.-

OBJECTIVES: The cholera outbreak in Yemen has become the largest in the recent history of cholera records, having reached more than 1.4 million cases since it started in late 2016. This study aimed to identify risk factors for cholera in this outbreak. METHODS: A case-control study was conducted in Aden in 2018 to investigate risk factors for cholera in this still-ongoing outbreak. In total, 59 cholera cases and 118 community controls were studied. RESULTS: The following risk factors were associated with being a cholera case in the bivariate analysis: a history of travelling and having had visitors from outside Aden Province; eating outside the house; not washing fruit, vegetables, and khat (a local herbal stimulant) before consumption; using common-source water; and not using chlorine or soap in the household. In the multivariate analysis, not washing khat and the use of common-source water remained significant risk factors for being a cholera case. CONCLUSIONS: Behavioural factors and unsafe water appear to be the major risk factors in the recent cholera outbreak in Yemen. In order to reduce the risk of cholera, hygiene practices for washing khat and vegetables and the use and accessibility of safe drinking water should be promoted at the community level.

Ameliorative effect of vitamin B12 on seminiferous epithelium of cimetidine-treated rats: a histopathological, immunohistochemical and ultrastructural study

Wael M. Elsaed,Raouf Fekry Bedeer,Mohamed Ahmed Eladl 대한해부학회 2018 Anatomy & Cell Biology Vol.51 No.1

Cimetidine is an H2 receptor antagonist that has an antiandrogenic effect. It intervenes with the conversion of testosterone into estrogen in the Sertoli cells with accompanying testicular structural changes. In the present study, the microscopic and the ultrastructural changes induced by cimetidine and the effect of vitamin B12 as a protective agent on rat testes were studied. Immunoexpression of estrogen receptor β (ERβ) in testes was evaluated. Twenty-four adult male rats were divided into four groups: control, cimetidine-treated, vitamin B12 treated, and combined cimetidine and vitamin B12 treated. The experimental rats were administered with cimetidine and/or vitamin B12 for 52 days. Group II rats showed marked atrophy of the seminiferous tubules with a significant increase in tubular diameter and decrease in the tubular luminal and epithelial areas. Ultrastructure of this group showed irregular Sertoli cells with basal cytoplasmic vacuolation and significantly thickened basement membrane. ERβ immunoexpression was similar to controls. Group III rats showed near normal seminiferous tubular structures with minimal cellular alterations and the immunoreactivity of the testicular sections was very close to normal. However, group IV rats showed markedly immunopositive detached cells, spermatids, and primary spermatocytes. Cimetidine interferes with the control of spermatogenesis as evidenced by microscopic and ultrastructural studies and affection of ERβ receptors and vitamin B12 has a protective action against this harmful effect.

Engineering nanocomposite of graphene quantum dots/carbon foam/ alginate/zinc oxide beads for efficacious removal of lead and methylene

Mohamed E. Mahmoud,Nesma A. Fekry,Amir M. Abdelfattah 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.115 No.-

The excessive industrial applications of methylene blue dye and lead ions with their high resistance tobiodegradation in water systems have led to their detection in water effluents as pollutants of major concernand therefore they must be removed by efficient techniques. Carbonaceous based materials as carbonfoam (C-Foam) and graphene quantum dots (GQDs) with sodium alginate are important reactiveadsorbents in water treatment. Therefore, a novel nanocomposite was assembled via crosslinking of zincoxide with carbon foam, GQDs and alginate to fabricate ZnO/C-Foam/GQDs/Alginate. This nanocompositeexhibited homogeneous and spherical particles with 20 nm average size. ZnO/C-Foam/GQDs/Alginate isdesigned to remove Pb(II) and methylene blue (MB) pollutants. The collected results referred to the optimumpH 6 and 7 for Pb(II) and MB, respectively. The computed thermodynamic parameters revealedendothermic and spontaneous reactions by the two pollutants providing DGo from 8.06 to13.67 kJ/mol for lead ion and from 6.23 to 8.19 kJ/mol for MB dye. The interfering species exhibitedalmost insignificant impact. ZnO/C-Foam/GQDs/Alginate nanocomposite confirmed successful reusabilityfor five successive regeneration cycles. Finally, ZnO/C-Foam/GQDs/Alginate nanocomposite providedexcellent removal trends for Pb(II) and MB pollutants from real water samples with100% and 92.2 %removal, respectively.