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Surface hardness,thermal,optical,and photon attenuation coefficients assessment for dysprosium-doped tellurite glasses

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Journal of Rare Earths 2023年第7期41卷 1083-1090,I0004页

作者： hesham m.h.zakaly D.E.Abulyazied h.A.Saudi B.m.Alotaibi Shams A.m.Issa Institute of Physics and Technology Ural Federal UniversityYekaterinburg620002Russia Faculty of Science Al-Azhar UniversityAssuit BranchAssuit71524Egypt Polymer Lab Department of PetrochemicalsEgyptian Petroleum Research InstituteNasr CityCairoEgypt Department of Physics Faculty of ScienceUniversity of TabukTabukSaudi Arabia Physics Department Faculty of ScienceAl-Azhar University(Girls Branch)Nasr CityCairoEgypt Department of Physics College of SciencePrincess Nourah Bint Abdulrahman UniversityP.O.Box 84428Riyadh11671Saudi Arabia

Using a melt-cooling process with the host glass,Dy_(2)O_(3)(1 wt%,2 wt%,3 wt%,and 4 wt%) doped tellurite glasses were produced.A(65-x)TeO_(2)-20B_(2)O_(3)-10Al_(2)O_(3)-SGeO_(2)-xDy_(2)O_(3) glass system was analyzed by Xray *** patterns have a hump at 2θ=27°-29° and no sharp peaks,indicating that all the glass samples are *** Vickers microhardness determines how resistant a glass is to persistent deformation produced by a harder *** scanning calorimetry(DSC) at 300-550℃ was used to evaluate the thermal properties of the Dy_x glass *** glass transition temperature T_g(small endothermic peak),start crystallization temperature T_x and crystallization temperature T_c can all be seen on the DSC thermogram(exothermic peaks).The UV-Vis transmittance and absorption spectra were *** optical data show that the values of E_d^(ir),E_g^(Ind) and E_U decrease as the amount of Dy_(2)O_(3)increases,indicating a narrowing of the tails due to localized states in the forbidden gap.A concentration quenching event occurs when Dy^(3+) concentrations are above a certain threshold(1%).The addition of Dy_(2)O_(3) increases glass density,while the addition of other Dy(Ⅲ) oxides increases sample *** radiation shielding values change as a consequence of density *** sample with the highest amount of Dy_(2)O_(3)(Dy_(4)) has stronger radiation shielding characteristics;hence,it is superior in terms of shielding outcomes at all energy *** Dy_x samples can be used in various forms of ionizing radiation shielding.

关键词： melt-cooling process DSC Dysprosium(Ⅲ)oxides Surface hardness Photon attenuation Rare earths

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Improving electrical,optical and radiation shielding properties of polyvinyl alcohol yttrium oxide composites

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Journal of Rare Earths 2023年第12期41卷 2002-2009,I0007页

作者： Shams A.m.Issa D.E.Abulyazied Albandari W.Alrowaily h.A.Saudi E.S.Ali A.m.A.henaish hesham m.h.zakaly Department of Physics Faculty of ScienceUniversity of TabukTabukSaudi Arabia Faculty of Science Al-Azhar UniversityAssiut BranchAssiut71524Egypt Polymer Lab Department of PetrochemicalEgyptian Petroleum Research InstituteNasr CityCairoEgypt Department of Physics College of SciencePrincess Nourah Bint Abdulrahman UniversityP.O.Box 84428Riyadh11671Saudi Arabia Physics Department Faculty of ScienceAl-Azhar University(Girls Branch)Nasr CityCairoEgypt Institute of Physics and Technology Ural Federal UniversityYekaterinburg620002Russia Physics Department Faculty of ScienceTanta UniversityTanta31527Egypt Istinye University Faculty of Engineering and Natural SciencesComputer Engineering DepartmentIstanbul34396Turkey

This research aims to study the impact of yttrium oxide on the radiation protection features of polyvinyl alcohol(PVA) for gamma shielding *** yttrium oxide(Y_(2)O_(3)) was instilled through the PVA matrix by different contents(x=0.1 wt%,0,3 wt%,0,7 wt%,0,9 wt%),The morphology of the prepared PVA/Y_(2)O_(3)composites was characterized using scanning electron microscopy(SEm).The samples were investigated using absorption edge,transmittance spectra and dielectric *** transmittance and the bandgap energy decrease as the Y2O3content increases while there is an increase in ε’ and ε" as well as the ac conductivity with the content increment of Y_(2)O_(3)till 0.7 wt%.The te mperature dependence of the dc conductivity was measured for all samples in the range of 260-460 K,and it increases with the temperature *** correlate the electrical characteristics of the PVA/Y_(2)O_(3)composites with their structure and evaluate electrical properties with the help of equivalent circuit matching with the experimentally electrical response in the impedance spectrum,the radiation protection properties were also investigated to get the radiation shielding performance of these PVA/Y_(2)O_(3)composite films with varying Y_(2)O(3)*** linear attenuation coefficient(μ),half value layer(T_(0.5)),and mass attenuation coefficient(μm) were *** to all obtained data,PVA/Y_(2)O_(3)composite films with various percentages(0.1 wt%,0.3 wt%,0.7 wt%,0.9 wt%) can be used as a radiation shielding material.

关键词： Yttriumoxide/PVA Electrical properties Optical properties Gamma shielding Rare earths

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Giardia duodenalis infection among rural communities in Yemen:A community-based assessment of the prevalence and associated risk factors

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Asian Pacific Journal of Tropical medicine 2017年第10期10卷 987-995页

作者： hesham m.Al-mekhlafi Endemic and Tropical Diseases Unit Medical Research CenterJazan UniversityJazanSaudi Arabia Department of Parasitology Faculty of MedicineUniversity of Malaya50603 Kuala LumpurMalaysia Department of Parasitology Faculty of Medicine and Health SciencesSana'a UniversitySana'aYemen

Objective: To investigate the prevalence and risk factors of Giardia infection among rural communities among rural communities in ***: In this cross-sectional study, a total of 605 stool samples were collected and screened for the presence of Giardia duodenalis(***) cysts and/or trophozoites by using three different diagnostic methods: direct smear, formalin-ether sedimentation,and trichrome staining.A pre-tested questionnaire was used to collect information on the demographic, socioeconomic, behavioural and environmental characteristics of the ***: Overall, 28.1%(170/605) of the participants were infected by *** prevalence was significantly higher among male participants compared to female(P = 0.034); however, it was not significant among different age groups(P > 0.05).Univariate and multivariate analyses identified four variables as the significant key risk factors of Giardia infection among the sampled *** are, in addition to being of the male gender, using unsafe water sources for drinking water, not washing hands after defecation, presence of other family members infected with Giardia, and close contact with domestic ***: The study reveals that Giardia infection is still prevalent among rural communities in *** provision of clean and safe drinking water, proper sanitation,and health education regarding personal hygiene practices, particularly handwashing, as well as identifying and treating infected family members is imperative and these interventions should be considered in a strategy to control intestinal parasites among these communities in order to curtail the transmission and morbidity caused by ***.

关键词： Giardia duodenalis Prevalence Risk factors Yemen

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hydraulic head difference at two sides of suspended waterproof curtain during multi-grade dewatering of excavation

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Underground Space 2023年第3期10卷 137-149页

作者： Tao Yang Li-yuan Tong m.hesham El Naggar Xin Yan School of Transportation Southeast UniversityNanjing 21000China Department of Civil and Environmental Engineering Western UniversityLondon N6A 5B9Canada

This paper proposes an approach to calculate the head difference at two sides of suspended waterproof curtains during multi-grade *** seepage during the dewatering process can be subdivided into three regions:(i)seepage in pit,(ii)seepage between cur-tains,and(iii)seepage outside the *** flow rate of the first region is equal to the pumping rate,and the flow rate of the second and third regions can be obtained by numerical analysis.A numerical model is established to simulate the seepage in the second and third regions and its performance is validated by using the measured data of a series of field *** flow rate of each region is then used to derive formulae for the head difference in conventional dewatering,which can be used to determine the head difference at two sides of each waterproof curtain during multi-grade *** proposed formula expresses the head difference as a function of the relative depth of the curtain inserted into the confined aquifer,the thickness of the aquifer,the distance between two curtains,and the anisotropy of the hydraulic conductivity of the *** proposed numerical approach is further validated by using data derived from numerical *** validation results demonstrated that the predictions of the proposed approach are acceptable and convenient.

关键词： head difference multi-grade dewatering Suspended waterproof curtain Confined aquifer

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Rare earth oxides doped NiO/γ-Al_2O_3 catalyst for oxidative dehydrogenation of cyclohexane

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Journal of Rare Earths 2015年第6期33卷 611-618页

作者： hany m.AbdelD ayem m.Faiz hesham S.Abdel-Samad Salah A.hassan Center of Research Excellence in Petroleum Refining & Petrochemicals (CoR E-PRP) King Fahd University of Petroleum & Minerals Chemistry Department College of Science King Faisal University Chemistry Department Faculty of Science Ain Shams University Surface Science Laboratory Physics Department King Fahd University of Petroleum &Minerals Department of Basic Sciences and Technology Community College Taibah University

The effect of rare earth oxides （RE=Ce, La, Gd, and Dy） doping of alumina support in NiO/7-A1203 system was investi- gated on its catalytic performance in oxidative dehydrogenation （ODh） of cyclohexane. The physicochemical properties of various samples were followed up through N2 physisorption, temperature programmed reduction （h2-TPR）, X-ray diffraction （XRD）, X-ray photoelectron spectroscopy （XPS） and potentiometric acid-base titration techniques. In the parent NiO/y-A1203 catalyst, Ni species were found to be strongly interacted with alumina surface. Addition of rare earth dopants to ）＇-A1203 in the catalyst system affected the nickel-alumina interaction and resulted in significant modifications in the catalytic performances in the ODh reaction. The results re- vealed the beneficial role of both La203 and Gd2Os doping in enhancing the ODh catalytic activity and selectivity to cyclohexene. h2-TPR and XPS results indicated that majority of Ni species in NiO/La203 modified T-A1203 were more weakly interacted with La203 and alumina whereas both NiO like species and nickel aluminate were present on the surface. Doping with cerium or dyspro- sium increased the nickel-support interaction and led to a decrease in surface nickel concentration. In case of doping with Ce, surface concentration of cerium oxide was higher than those of the other RE oxides; the doped catalyst reached its steady state activity faster than the other catalysts. The acid-base results suggested that RE metals were interacted most likely with acidic surface hydroxyl groups. The degree of nickel-alumina interaction decreased in the following order： LaAI〉GdAI〉CeAI〉DyA1.

关键词： nickel oxide rare-earth oxides doping Ni-A1203 interaction surface acidity oxidative dehydrogenation cyclohexane rare earths

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Numerical modeling of time-dependent deformation and induced stresses in concrete pipes constructed in Queenston shale using micro-tunneling technique

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Journal of Rock mechanics and Geotechnical Engineering 2018年第2期10卷 290-309页

作者： hayder mohammed Salim Al-maamori m.hesham El Naggar Silvana micic Department of Civil and Environmental Engineering Western University Geotechnical Research Center Western University

Effects of time-dependent deformation（TDD） on a tunnel constructed using the micro-tunneling technique in Queenston shale（QS） are investigated employing the finite element method. The TDD and strength parameters of the QS were measured from tests conducted on QS specimens soaked in water and lubricant fluids（LFs） used in micro-tunneling such as bentonite and polymer solutions. The numerical model was verified using the results of TDD tests performed on QS samples, field measurements of some documented projects, and the closed-form solutions to circular tunnels in swelling rock. The verified model was then employed to conduct a parametric study considering important micro-tunneling design parameters, such as depth and diameter of the tunnel, in situ stress ratio（K;）, and the time lapse prior to replacing LFs with permanent cement grout around the tunnel. It was revealed that the time lapse plays a vital role in controlling deformations and associated stresses developed in the tunnel *** critical case of a pipe or tunnel in which the maximum tensile stress develops at its springline occurs when it is constructed at shallow depths in the QS layer. The results of the parametric study were used to suggest recommendations for the construction of tunnels in QS employing micro-tunneling.

关键词： Numerical model micro-tunneling Queenston shale(QS) Lubricant fluids(LFs)

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Effective damping of local low frequency oscillations in power systems integrated with bulk PV generation

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Protection and Control of modern Power Systems 2021年第1期6卷 512-524页

作者： Ahmed hesham Abd El-Kareem mohamed Abd Elhameed mahmoud m.Elkholy Operation Engineer at New Capital Power Plant New Capital CityEgypt Electrical Power and machines Department Faculty of EngineeringZagazig UniversityZagazigEgypt

high penetration of renewable sources into conventional power systems results in reduction of system inertia and noticeable low-frequency oscillations (LFOs) in the rotor speed of synchronous generators. In this paper, we propose effective damping of LFOs by incorporating a supplementary damping controller with a photovoltaic (PV) generating station, where the parameters of this controller are coordinated optimally with those of a power system stabilizer (PSS). The proposed method is applied to damp local electromechanical modes by studying a system comprising a synchronous generator and a PV station connected to an infinite bus. The PV station is modeled following the instructions of the Western Electricity Coordinating Council. The problem is modeled as an optimization problem, where the damping ratio of the electromechanical modes is designed as the objective function. Constraints including upper and lower limits of decision parameters and damping ratio of other modes are considered by imposing penalties on the objective function. Different optimization algorithms are used to pursue the optimal design, such as political, improved gray wolves and equilibrium optimizers. The results validate the effectiveness of the proposed controller with PSS in damping local modes of oscillations.

关键词： Low frequency oscillations Damping controller PV WECC

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Wetting effects and strength degradation of swelling shale evaluated from multistage triaxial test

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Underground Space 2019年第2期4卷 79-97页

作者： hayder mohammed Salim Al-maamori m.hesham El Naggar Silvana micic Civil and Environmental Engineering Department The University of Western Ontario1151 Richmond St.LondonOntario N6A 5B9Canada Geotechnical Research Centre Civil and Environmental Engineering DepartmentThe University of Western Ontario1151 Richmond St.LondonOntario N6A 5B9Canada

The multistage triaxial compression test was mainly utilized in this research to investigate the degradation in the strength of swelling shale under different wetting *** samples were tested in four different conditions:(1)under their natural moisture content denoted as intact,and after soaking in,(2)water,(3)polymer solution,and(4)bentonite solution,*** experimental results showed that a considerable decrease in the shale’s strength was noted after soaking in water and the lubricant fluids(LFs).The polymer solution caused the least decrease in the strength compared to other *** envelopes of the tested shale were constructed for intact and soaked *** envelopes showed fair agreement between the single stage and the multistage triaxial compression test results,indicating suitability of the multistage triaxial compression test for the tested swelling shale.

关键词： multistage Triaxial compression Swelling shale Strength degradation Strength envelopes

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Drought-mediated modulation in metabolomic Profiling of Nigella Sativa Leaf, Growth, Ecophysiology and Antioxidants

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Phyton-International Journal of Experimental Botany 2023年第12期92卷 3323-3344页

作者： Khalid Rehman hakeem hesham F.Alharby m.Irfan Qureshi Department of Biological Sciences Faculty of ScienceKing Abdulaziz UniversityJeddahSaudi Arabia Princess Dr.Najla Bint Saud Al-Saud Center for Excellence Research in Biotechnology King Abdulaziz UniversityJeddahSaudi Arabia Department of Public health Daffodil International UniversityDhakaBangladesh Department of Biotechnology Jamia Millia IslamiaNew DelhiIndia

Abiotic stresses,including drought,have been found to affect the growth and medicinal quality of numerous *** proposed study aims to study the effects of different drought regimes on the metabolic profile,growth,ecophysiology,cellular antioxidants,and antioxidant potential of Nigella sativa(Black cumin)***-day-old seedlings of *** were exposed to three regimes of drought(control,moderate and high)for a ***/mS metabolic profile of the leaf reveals the presence of more than a hundred metabolites belonging to anthocyanins,chalcones,dihydro flavonoids,flavonoids,flavanols,flavones,flavonoid carbonoside,isoflavones,*** was found to alter the contents of identified *** stress-induced oxidative stress and increased production of hydrogen peroxide and superoxide *** changes,activities of antioxidant enzymes,contents of antioxidants,and proline were significantly high under drought to protect against the low water ***,stressed leaf extract had higher antioxidant ***,*** leaf bears multiple metabolic pathways and can tolerate a higher degree of drought or osmotic stress.

关键词： Nigella sativa metabolomics drought antioxidant mechanism flavonoids

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Prevalence and risk factors of Blastocystis infection among underprivileged communities in rural malaysia

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Asian Pacific Journal of Tropical medicine 2017年第5期10卷 467-473页

作者： Nabilah Amelia mohammad hesham m.Al-mekhlafi Norhayati moktar Tengku Shahrul Anuar Centre of medical Laboratory Technology Faculty of Health SciencesUniversiti Teknologi MARAPuncak Alam Campus Endemic and Tropical Disease Unit Medical Research CenterJazan University Department of Parasitology Faculty of Medicine and Health SciencesSana’a University Department of Pre-Clinical Sciences Faculty of Medicine and Health SciencesUniversiti Tunku Abdul RahmanSungai Long Campus Integrative Pharmacogenomics Institute Universiti Teknologi MARAPuncak Alam Campus

Objective:To determine the prevalence and risk factors of Blastocystis among underprivileged communities living in rural malaysia. methods:This cross-sectional study was conducted among 253 participants aged between 1 and 85 years. Stool samples were examined using Wheatley's trichrome stain after in-vitro cultivation in Jones' medium to detect the presence of Blastocystis. Information pertaining to the demography,socioeconomic and environment were collected using pre-validated questionnaires. Results:The total prevalence of Blastocystis infection was 40.7%. The multiple logistic regression analysis revealed that age ≥15 years(OR = 2.72; 95%CI = 1.47-5.04) and presence of infected family members(OR = 8.56; 95%CI = 4.47-16.38) were the significant risk factors associated with blastocystosis in these communities. Conclusions:Blastocystosis is revealed through this study to be still prevalent among Orang Asli communities in rural malaysia. The two main approaches that should be implemented by the public health authority in battling this infection would be the screening of other family members and giving treatment to the infected individuals. moreover,it is imperative for health education on good personal and food hygiene practices are provided in order to reduce the morbidity and transmission of Blastocystis infection among the Orang Asli in their communities meaningfully.

关键词： Blastocystis Prevalence Risk factors malaysia

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