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.

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.

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.

Controlling the Microstructure and Magnetic Properties of Mn-Zn Ferrites Nanopowders Synthesized by Co-Precipitation Method

M. M. Rashad,M. I Nasr 대한금속·재료학회 2012 ELECTRONIC MATERIALS LETTERS Vol.8 No.3

Nanocrystalline manganese zinc ferrites (MnXZn1-XFe2O4) powders with Mn 2+ions ratio (x) varying from 0.3to 0.9 have synthesized by co-precipitation method. The results show that single MnXZn1-XFe2O4 phase forms at annealing temperature 1000°C for 2 h. The lattice parameter and crystallite size of the produced Mn-Zn ferrites powders increase with increasing the Mn 2+ion molar ratio. The microstructure and magnetic properties of the produced MnXZn1-XFe2O4 powders depend on the temperature and Mn 2+ion content. The morphology of Mn0.8Zn0.2Fe2O4 powder clearly appears as a homogeneous octahedral-like structure. The saturation magnetization of the Mn-Zn ferrite powders increase as the result of increasing Mn 2+ion ratio to 0.8. A high saturation magnetization (73.64 emu/g) achieves for the Mn0.8Zn0.2Fe2O4 powders annealed at 1100°C for 2 h.

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 $A_i$(${\infty}$).

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.

A Concise on the Effect of Calcium Oxide on the Properties of Alkali-Activated Materials: A Manual for Civil Engineers

Alaa M. Rashad 한국콘크리트학회 2024 International Journal of Concrete Structures and M Vol.18 No.2

As known, calcium oxide (CaO) is an alkaline material, which can be used widely to increase the clay-containing soils load carrying capacity, to produce aerated concrete and calcium aluminate cement. In the last few years, introducing CaO into alkali-activated materials (AAMs) became a hot topic and attained more attention than other times. Generally, CaO can be incorporated into AAMs as an additive/a part of the main precursor and a sole activator without/with an auxiliary activator. Incorporating CaO into the matrices may improve some properties and worsen others. This mainly depends on the ratio of CaO, curing conditions, activator type and activator concentration, precursor type and testing age. This review collected, summarized and analyzed the available studies focused on the effect of CaO on the fresh (reaction kinetic, workability, setting time) and hardened (mechanical strength, durability and length change) properties of AAMs. In addition, some recommendations for future works were included. The results showed that the inclusion of CaO in AAMs decreased workability and setting time. In spite of there are contradictory results about the effect of CaO on the compressive strength of AAMs, most of them reported higher compressive strength, especially at the early ages. The incorporation of CaO up to 5% in the matrix is more effective than the incorporation of higher ratios. The inclusion of CaO in the matrix decreased water absorption, decreased total porosity, increased wetting/drying as well as acid attack resistivity. The CaO (5–10%) can be used as a sole activator for precursors. Auxiliary activators such as Al2(SO4)3, Na2CO3, Na2SiO3, Na2SO4, CaSO4, NaOH, Ca(NO3)2, NaNO3, Mg(NO3)2, Mg(HCOO)2, Ca(HCOO)2, SO3, gypsum and MgO can be used to enhance the compressive strength of CaO-activated materials, especially at the early ages.

One-Pot Robust Dyeing of Cotton Fabrics with Multifunctional Chamomile Flower Dyes

Manal M. El-Zawahry,Hala S. El Khatib,Gehan M. Shokry,Hager Gamal Rashad 한국섬유공학회 2022 Fibers and polymers Vol.23 No.8

Our study focused on the extraction of biologically active compounds in the form of eco-friendly dyes from driedchamomile flower (CF) powder using three different solvents, as well as the development of an approach to the simultaneousdyeing and finishing of cationized cotton fabrics, a process which can impart multifunctional properties. These extracted dyeswere successfully used as reducing and stabilizing agents in the synthesis of silver nanoparticles (AgNPs), whichfunctionalized both the dye and the fabric. This green, value-added dyeing approach is needed for the production ofbiomedical textiles, especially in the healthcare sector. Our results revealed that the total phenolic content (TPC) and totalflavonoid content (TFC) were significantly higher in dyes extracted using ethanol and methanol than those extracted using anaqueous solution. Furthermore, cotton fabrics dyed with these three dyes exhibited a wide range of colors with good washingfastness, excellent UV protection, and antioxidant properties. The simultaneous dyeing and finishing of cotton fabrics via thein situ green synthesis CF extracts/AgNPs dyes enhanced the K/S values and the antimicrobial, antifungal, and antioxidantactivity of the fabrics while still providing adequate UV protection. This process also improved the washing fastness anddurability, which is important for biomedical applications.

Controlling the Optical and Magnetic Properties of Nanostructured Cuprous Oxide Synthesized from Waste Electric Cables

S. M. Abdelbasir,S. M. El-Sheikh,M.M. Rashad,D.A. Rayan 대한금속·재료학회 2018 ELECTRONIC MATERIALS LETTERS Vol.14 No.4

Cuprous oxide Cu2Onanopowders were purposefully synthesised from waste electric cables (WECs) via a simple precipitationroute at room temperature using lactose as a reducing agent. In this regard, dimethyl sulfoxide (DMSO) was first appliedas an organic solvent for the dissolution of the cable insulating materials. Several parameters were investigated during dissolutionof WECs such as dissolution temperature, time and solid/liquid ratio to determine the dissolution percentage of theinsulating materials in DMSO. The morphology and the optical properties of the formed Cu2Oparticles were investigatedusing X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopyand UV–visible–near IR spectrophotometer. XRD data confirmed the presence of single crystalline phase of Cu2Onanoparticles. FE-SEM and TEM images revealed spherical, cubic and octahedral shapes with the various particle sizesranged from 16 to 57 nm depending on the synthesis conditions. A possible mechanism explaining the Cu2Onanostructuresformation was proposed. The band gap energies of the Cu2Onanostructures were estimated and the values were locatedbetween 1.5 and 2.08 eV. Photoluminescence spectroscopy analysis clearly showed a noticeably blue-shifted emission forthe synthesized samples compared to spectrum of the bulk. Eventually, magnetic properties of the synthesized nanoparticleshave been measured by vibrating sample magnetometer and the attained results implied that the synthesized particles areweakly ferromagnetic in nature at normal temperature.

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.