Synthesis and characterization of mesoporous anatase TiO2nanostructures via organic acid precursor process for dye-sensitized solar cells applications

M.M. Rashad,A.E. Shalan,Monica Lira-Cantu,M.S.A. Abdel-Mottaleb 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.6

Titania (TiO2) nanoparticles have been synthesized using organic precursor technique. The titania nanoparticles were characterized. The results indicated that the prepared titanium oxalate and citrate precursors were transformed to anatase TiO2 phase at temperature 400 8C for 2 h. Dye-sensitized solar cells were assembled using the prepared nanocrystalline TiO2 with large surface area. The specific surface area SBET was 80.9 and 78.6 m2/g using oxalic and citric acids, respectively. The power efficiency was 3.5 and 2.4%. A brief discussion on the possible reasons behind the low power conversion efficiency observed for these type of solar cells was reported.

The optimal system for series systems with warm standby components and a repairable service station

Rashad, A.M.,El-Sherbeny, M.S.,Gharieb, D.M. The Korean Reliability Society 2010 International Journal of Reliability and Applicati Vol.11 No.2

This paper deals with the reliability and availability characteristics of three different series system configurations with warm standby components and a repairable service station. The failure time of the primary and warm standby are assumed to be exponentially distributed with parameters ${\lambda}$ and ${\alpha}$ respectively. The repair time distribution of each server is also exponentially distributed with parameter ${\mu}$. The breakdown time and the repair time of the service station are also assumed exponentially distributed with parameters ${\gamma}$ and ${\beta}$ respectively. We derive the reliability dependent on time, availability dependent on time, the mean time to failure, $MTTF_i$, and the steady-state availability $A_i$(${\infty}$) for three configurations and perform comparisons. Comparisons are made for specific values of distribution parameters and of the cost of the components. The three configurations are ranked based on: $MTTF_i$, $A_i$(${\infty}$), and $C_i/B_i$ where $B_i$ is either $MTTF_i$ or $A_i$(${\infty}$).

Magnetic Properties of La3+-ion-doped Polycrystalline Z-type Hexaferrite Powders Synthesized via the Co-precipitation Method

M. M. Rashad,M. Rasly,I. A. Ibrahim,H. M. El-Sayed,A. A. Sattar 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.63 No.3

Co2Z-type hexagonal ferrite powders doped with La3+ ions (Ba3−XLaxCo2Fe24O41 where x =0.0, 0.05, 0.10 and 0.15) were prepared using a co-precipitation method. The results revealed thatsingle-phase Co2Z-type ferrite was formed from the precipitated precursor in the presence of sodiumdodecyl sulfate (SDS) as an anionic surfactant. The obtained precursor was preheated at 600 ℃ for4 h then post annealed at 1300 ℃ for 6 h. The crystallite size increased with increasing of La3+-ion molar ratio. The microstructure of the formed powders appeared to be a hexagonal-plateletlikestructure. The DC resistivity of the obtained Co2Z decreased with increasing La3+ content. The saturation magnetization (Ms = 53.7 - 55.5 emu/g) was slightly increased with increasingsubstitution of La3+ ion. Moreover, two resonance frequency peaks were observed through theimaginary part of complex magnetic permeability; meanwhile, a decrease in the real part of thecomplex magnetic permeability was observed through the X-band frequencies.

The optimal system for series systems with warm standby components and a repairable service station

A. M. Rashad,M. S. EL-Sherbeny,D. M. Gharieb 한국신뢰성학회 2010 International Journal of Reliability and Applicati Vol.11 No.2

This paper deals with the reliability and availability characteristics of three different series system configurations with warm standby components and a repairable service station. The failure time of the primary and warm standby are assumed to be exponentially distributed with parameters λ and α respectively. The repair time distribution of each server is also exponentially distributed with parameter μ . The breakdown time and the repair time of the service station are also assumed exponentially distributed with parametersγ and β respectively. We derive the reliability dependent on time, availability dependent on time, the mean time to failure, MTTFi , and the steady-state availability Ai(∞) for three configurations and perform comparisons. Comparisons are made for specific values of distribution parameters and of the cost of the components. The three configurations are ranked based on: MTTFi , Ai(∞), and Ci/ Bi where Bi is either MTTFi or Ai(∞).

Public Sentiment Analysis and Topic Modeling Regarding COVID-19’s Three Waves of Total Lockdown: A Case Study on Movement Control Order in Malaysia

A.H. Alamoodi,Mohammed Rashad Baker,O.S. Albahri,B.B. Zaidan,A.A. Zaidan,Wing-Kwong Wong,Salem Garfan,A.S. Albahri,Miguel A. Alonso,Ali Najm Jasim,M. J. Baqer 한국인터넷정보학회 2022 KSII Transactions on Internet and Information Syst Vol.16 No.7

The COVID-19 pandemic has affected many aspects of human life. The pandemic not only caused millions of fatalities and problems but also changed public sentiment and behavior. Owing to the magnitude of this pandemic, governments worldwide adopted full lockdown measures that attracted much discussion on social media platforms. To investigate the effects of these lockdown measures, this study performed sentiment analysis and latent Dirichlet allocation topic modeling on textual data from Twitter published during the three lockdown waves in Malaysia between 2020 and 2021. Three lockdown measures were identified, the related data for the first two weeks of each lockdown were collected and analysed to understand the public sentiment. The changes between these lockdowns were identified, and the latent topics were highlighted. Most of the public sentiment focused on the first lockdown as reflected in the large number of latent topics generated during this period. The overall sentiment for each lockdown was mostly positive, followed by neutral and then negative. Topic modelling results identified staying at home, quarantine and lockdown as the main aspects of discussion for the first lockdown, whilst importance of health measures and government efforts were the main aspects for the second and third lockdowns. Governments may utilise these findings to understand public sentiment and to formulate precautionary measures that can assure the safety of their citizens and tend to their most pressing problems. These results also highlight the importance of positive messaging during difficult times, establishing digital interventions and formulating new policies to improve the reaction of the public to emergency situations.

Physical and nuclear shielding properties of newly synthesized magnesium oxide and zinc oxide nanoparticles

Rashad, M.,Tekin, H.O.,Zakaly, Hesham MH.,Pyshkina, Mariia,Issa, Shams A.M.,Susoy, G. Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.9

Magnesium oxide (MgO) and Zinc oxide (ZnO) nanoparticles (NPs) have been successfully synthesized by solid-solid reaction method. The structural properties of ZnO and MgO NPs were studied using X-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD results indicated a formation of pure MgO and ZnO NPs. The mean diameter values of the agglomerated particles were around to be 70 and 50 nm for MgO and ZnO NPs, respectively using SEM analysis. Further, a wide-range of nuclear radiation shielding investigation for gamma-ray and fast neutrons have been studied for Magnesium oxide (MgO) and Zinc oxide (ZnO) samples. FLUKA and Microshield codes have been employed for the determination of mass attenuation coefficients (μ_m) and transmission factors (TF) of Magnesium oxide (MgO) and Zinc oxide (ZnO) samples. The calculated values for mass attenuation coefficients (μ_m) were utilized to determine other vital shielding properties against gamma-ray radiation. Moreover, the results showed that Zinc oxide (ZnO) nanoparticles with the lowest diameter value as 50 nm had a satisfactory capacity in nuclear radiation shielding.

Quantum Confinement Observation of Milled Potassium Chloride

M. Rashad,E. F. M. El-Zaidia,S. E. AL Garni,A. A. A. Darwish 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2019 NANO Vol.14 No.6

Potassium chloride (KCl) nanoparticles were synthesized by ball milling technique with different milling time. The e®ect of milling time on structural and optical properties was investigated. The structural properties of the purchased samples are characterized by Raman spectroscopy, scanning electron microscope and X-ray diffraction techniques. The Raman spectroscopy of the KCl hints at an excellent alloying behavior of those compounds and a preferred crystal structure for certain composition. The optical band is calculated by analyzing the spectral behavior of the absorption cofficient in the absorption region which revealed direct transitions. The value optical band increases (4.02–5.11 eV) with increasing milling time (0–15 h) due to quantum confinement after the ball milling process. The refractive and absorption indices were calculated for all samples. The model of Wemple–DiDomenico was used to calculate the dispersion parameters. The nonlinear susceptibility of the third order and the nonlinear refractive index were calculated by linear optical parameters using the generalized Miller rule.

Effect of elevated temperature on physico-mechanical properties of metakaolin blended cement mortar

A. M. Rashad,M. S. Morsy,H. A. El-Nouhy 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.31 No.1

An experimental investigation was conducted to evaluate the performance of mortars with and without Metakaolin (MK) exposed to elevated temperatures 200oC, 400oC, 600oC and 800oC for two hours. The binder to sand ratio was kept constant (1:5.23). The ordinary Portland cement (OPC) was replaced with MK at 0%, 5%, 10% 20% and 30%. All mixtures were designed to have a flow of 94 ±5%. The compressive strength of mortars before and after exposure to elevated temperature was determined. The formation of various decomposition phases were identified using X-ray diffractometry (XRD) and differential thermal analysis (DTA). The microstructure of the mortars was examined using scanning electron microscope (SEM). Test results indicated that MK improves the compressive strength before and after exposure to elevated temperature and that the 20% cement replacement of MK is the optimum percentage.

Morphological, ultrastructural, and biochemical changes induced by sodium fluoride in the tongue of adult male albino rat and the ameliorative effect of resveratrol

Emtethal M. El-Bestawy,Asmaa M. Tolba,Walaa A. Rashad 대한해부학회 2022 Anatomy & Cell Biology Vol.55 No.4

Little knowledge is available about the effects of fluoride exposure on the tongue. This study evaluated the effects of sodium fluoride (NaF) on the tongue ultrastructure and detected the ameliorative effects of resveratrol. Forty adult albino rats were separated into 4 groups: the control group was given a balanced diet and purified water. The NaF treated group: received 10 mg/kg/d dissolved in 2.5 ml distilled water once daily for 30 days orally. The NaF+resveratrol group: received NaF 10 mg/ kg/d orally together with resveratrol in a dose of 30 mg/kg daily for 30 days. The resveratrol group was subjected to resveratrol in a dose of 30 mg/kg/d by oral gavage for 30 days. Sections were stained with hematoxylin & eosin, and Masson’s trichrome. Tumor necrosis factor α immunohistochemical study and electron microscopic examinations were done. The oxidative stress markers malondialdehyde, antioxidant reduced glutathione, and the total antioxidant capacity were measured. The NaF group revealed ulceration, necrotic muscle fibers, distorted papillae and a significant increase in malondialdehyde level, and a significant decrease in glutathione and the total antioxidant levels. In the NaF+resveratrol group, pathological changes were less, and the oxidant levels were decreased by the administration of resveratrol with NaF. In conclusion, NaF adversely affects the ultrastructure of the adult rat tongue and resveratrol can ameliorate this effect.

HPLC–DAD–MS/MS profiling of standardized rosemary extract and enhancement of its anti-wrinkle activity by encapsulation in elastic nanovesicles

Shahira M. Ezzat,Maha M. Salama,Aliaa N. ElMeshad,Mahmoud H. Teaima,Laila A. Rashad 대한약학회 2016 Archives of Pharmacal Research Vol.39 No.7

The anti-wrinkle activity of defatted rosemaryextract (DER) was assessed, and its effect was optimized byencapsulation in transferosomes (TFs). DER was standardizedto a rosmarinic acid content of 4.58 ± 0.023 mg%using reversed-phase high performance liquid chromatography(Rp-HPLC), and its components were identified byHPLC-diode array detection-tandem mass spectrometry. In vitro free radical scavenging assays showed DER hadhigh free radical scavenging activity against 2,2-diphenyl-2-picryl hydrazyl, 2,20-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and superoxide radicals. DER also inhibitedbleaching of b-carotene with high Fe(III) and Fe(II)chelating ability. In vivo anti-wrinkle activities of topicallyapplied DER (20, 50, and 100 mg) and a TF formulation(TF4, 20 mg of DER) were evaluated in UVB-irradiatedmice using a wrinkle scoring method, metalloproteinase(MMP) expression, and histopathology. Among thenanovesicles, TF4 was the most deformable, and had anacceptable size and encapsulation efficiency and enhancedpermeation of DER through rat skin compared with unencapsulatedDER. DER (50 and 100 mg) and TF4 significantlyinhibited MMP-2 and MMP-9 expression andimproved wrinkle scores. DER and TF4 moderatelydecreased epidermal thickness without pigmentation. DERis a potent natural antioxidant for combating skin aging. Moreover, encapsulation of DER in TFs will enhance itsskin permeation and anti-wrinkle activity.