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用于高性能硫化镉敏化太阳能电池对电极的硫化铜/还原氧化石墨烯纳米复合材料的合成(英文)

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新型炭材料 2018年第1期33卷 26-35页

作者： Amr Hessein ahmed abd el-Moneim Department of Materials Science and Engineering Egypt-Japan University of Science and TechnologyNew Borg El Arab City Alexandria 21934 Egypt Department of Mathematical and Physical Engineering Faculty of Engineering ( Shoubra) Benha U

用一釜水热合成法制备了硫化铜/还原氧化石墨烯纳米复合材料,改变前驱体中石墨烯含量,得到具有不同石墨烯含量的纳米复合材料。所制备的纳米复合材料首先和聚偏氟乙烯粘结剂混合,再涂覆在SnO2 _(x-)Fx基体上,得到以CdS敏化TiO2为负极的... 详细信息

用一釜水热合成法制备了硫化铜/还原氧化石墨烯纳米复合材料,改变前驱体中石墨烯含量,得到具有不同石墨烯含量的纳米复合材料。所制备的纳米复合材料首先和聚偏氟乙烯粘结剂混合,再涂覆在SnO2 _(x-)Fx基体上,得到以CdS敏化TiO2为负极的量子点太阳能电池的对电极,并与传统的Cu2 S/Cu对电极进行比较。用场发射扫描电子显微镜、X-射线衍射、拉曼光谱、循环伏安和阻抗谱技术表征了纳米复合材料对电极的微观结构和性能。结果表明:硫化铜/还原氧化石墨烯纳米复合材料优于Cu2 S/Cu对电极。前驱体中石墨烯的含量显著影响了硫化铜纳米晶的化学计量比和形貌。当前驱体石墨烯含量在中等水平下,获得了具有更多供S2_(-x)离子还原的活性位的优化的硫化铜/还原氧化石墨烯纳米复合材料。以此优化的纳米复合材料为对电极制备的量子点太阳能电池在100 mW/cm2的光照强度下具有高的、稳定的和可重复的_(2.)36%的能量转化效率,高于用Cu2 S/Cu为对电极的能量转化效率。此性能的提升归因于硫化铜纳米晶和导电的还原氧化石墨烯之间的协同作用,还原氧化石墨烯充当共催化剂和导电促进剂,降低对电极的内阻并加快多硫化物的还原。

关键词：还原氧化石墨烯硫化铜量子点太阳能电池多硫化物电解质

Review on friction stir welding of dissimilar magnesium and aluminum alloys: Scientometric analysis and strategies for achieving high-quality joints

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Journal of Magnesium and Alloys 2023年第11期11卷 4082-4127页

作者： mohamed M.Z.ahmed mohamed M.el-Sayed Seleman Dariusz Fydrych Gürel ÇAM Department of Mechanical Engineering College of Engineering at Al KharjPrince Sattam Bin Abdulaziz UniversityAl Kharj 11942Saudi Arabia Department of Metallurgical and Materials Engineering Faculty of Petroleum and Mining EngineeringSuez UniversitySuez 43512Egypt Faculty of Mechanical Engineering and Ship Technology Institute of Machines and Materials TechnologyGdańsk University of TechnologyGabriela Narutowicza Street 11/12Gdańsk 80-233Poland Department of Mechanical Engineering Iskenderun Technical UniversityIskenderunHatay 31200Turkiye

Magnesium and aluminum alloys continually attract interest as lightweight structural materials for transport applications. However, joining these dissimilar alloys is very challenging. The main obstacle that hinders progress in dissimilar Mg-Al joining is the formation of brittle intermetallic compounds(IMCs). As a solid-state joining technique, FSW is an excellent candidate to attenuate the deleterious IMC effects in dissimilar Al-Mg joining due to the inherent low heat inputs involved in the process. However, the IMCs, namely Al_(3)Mg_(2) and Al_(12)Mg_(17) phases, have also been reported to form during Al-Mg dissimilar FSW;their amount and thickness depend on the heat input involved;thus,the weld parameters used. Since the heat dissipated in the material during the welding process significantly affects the amount of IMCs,the heat input during FSW should be kept as low as possible to control and reduce the amount of IMCs. This review aims to critically discuss and evaluate the studies conducted in the dissimilar Al/Mg FSW through a scientometric analysis and also with a focus on the strategies recently applied to enhance joint quality. The scientometric analysis showed that the main research directions in Mg/Al FSW are the technological weldability of aluminum and magnesium during FSW, structural morphology, and mechanical properties of dissimilar welded joints. Considering the scope of application of the aforementioned joints, the low share of articles dealing with environmental degradation and operational cracking is surprising. This might be attributed to the need for well-developed strategies for obtaining high-quality and sustainable joints for applications. Thus, the second part of this review is conventional, focusing mainly on the new strategies for obtaining high-quality Mg/Al joints. It can be concluded that in addition to the necessity to optimum welding parameters to suppress the excessive heat to limit the amount and thickness of IMC formed and improv

关键词： Friction stir welding(FSW) Al-alloys Mg-alloys Dissimilar material welding Intermetallics Weld performance

Pegylated interferon α/ribavirin therapy enhances bone mineral density in children with chronic genotype 4 HCV infection

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World Journal of Pediatrics 2017年第4期13卷 346-352页

作者： ahmed Megahed Nanees Salem Abeer Fathy Tarik Barakat Mona abd el Latif Alsayed Suzy abd el Mabood Khaled R Zalata ahmed F abdalla Pediatric Gastroenterology and Hepatology Unit Mansoura University Children's HospitalFaculty of MedicineMansoura UniversityEgypt Pediatric Endocrinology Unit Mansoura University Children's HospitalFaculty of MedicineMansoura UniversityEgypt Pediatric Hematology&Oncology Unit Mansoura University Children's HospitalFaculty of MedicineMansoura UniversityEgypt Pathology Department Faculty of MedicineMansoura UniversityEgypt

Background:The impact of chronic hepatitis C (CHC) on bone mineral density (BMD) has been well studied in adults with a relative paucity of data in children,especially concerning effect of treatment with pegylated interferon (PEG-IFN) plus ribavirin (RV).In the current work,we assessed prospectively changes in BMD in children with CHC before,during,and after ***:Forty-six consecutive children with noncirrhotic genotype 4 CHC were subjected to dual-energy X-ray absorptiometry at baseline,24 weeks,48 weeks of therapy and 24 weeks after ***,bone mineral content (BMC),and Z score of lumbar spine (L2-L4) were *** pubertal stage,viral load,liver function tests,serum calcium,phosphorus,alkaline phosphatase,parathyroid hormone,and liver histopathology were assessed in all included ***:Thirty (65.2%) patients had normal BMD,10 (21.7%) were at risk for low BMD,and 6 (13.1%) had low BMD for chronological *** with low BMD were significantly older (P=0.001),with higher frequency of delayed puberty than other groups (P=0.002).Baseline densitometric parameters (BMD & BMC) were significantly positively correlated with patients' age,weight,height,body mass index and hemoglobin level;while they were insignificantly correlated with basal viral load,histopathology activity index and fibrosis *** parameters improved significantly on PEG-IFN plus RV treatment,this improvement was found to be sustainable 24 weeks after ***:Low BMD is detectable in a proportion of CHC *** therapy leads to a sustainable increase in BMD.

关键词： bone mineral density chronic hepatitis C pegylated interferon ribavirin

The vitreomacular interface in different types of agerelated macular degeneration

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International Journal of Ophthalmology(English edition) 2017年第2期10卷 246-253页

作者： mohamed abd elM onaem el-Hifnawy Hisham Ali Ibrahim Amir Ramadan Gomaa mohamed A elmasry Ophthalmology Department Alexandria University Faculty of MedicineKhartoum SquareAzaritaAlexandria 21526Egypt

AIM： To evaluate the vitreomacular interface in cases with wet age-related macular degeneration（AMD） and to compare them to eyes with dry AMD and normal ***： This was a cross-sectional comparative study that included 87 eyes with wet AMD,42 eyes with dry AMD and 40 eyes without AMD as a control *** coherence tomography（OCT） examination was performed for all patients to assess the vitreomacular ***： In the wet AMD group,34.5% of cases had vitreomacular adhesion（VMA）.Only 14.3% of dry AMD cases and 10% of control cases had *** was a significant difference between the control group and the wet AMD group（P=0.004） as well as the dry and wet AMD group（P=0.017）.There was also a significant difference between the incidence of VMA in patients with subretinal choroidal neovascularization（CNV,type 1） and intraretinal CNV（type 2 or type 3）（P=0.020）.CONCLUSION： There is an association between posterior vitreous attachment and *** is also an increased incidence of VMA with intra-retinal CNV.

关键词： age-related macular degeneration vitreomacular interface optical coherence tomography macula

Amination of biochar surface from watermelon peel for toxic chromium removal enhancement

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Chinese Journal of Chemical Engineering 2021年第8期34卷 199-222页

作者： mohamed A.el-Nemr Ibrahim M.A.Ismail Nabil M.abdelmonem ahmed el Nemr Safaa Ragab Department of Chemical Engineering Faculty of EngineeringCairo UniversityGizaEgypt Renewable Energy Program Zewail City of Science and TechnologyEgypt Environmental Division National Institute of Oceanography and FisheriesKayet BeyEl-AnfoushyAlexandriaEgypt

Watermelon peel residues were used to produce a new biochar by dehydration *** new biochar has undergone two methods of chemical modification and the effect of this chemical modification on its ability to adsorb Cr(VI)ions from aqueous solution has been *** biochars,Melon-B,Melon-BO-NH_(2) and Melon-BO-TETA,were made from watermelon peel via dehydration with 50%sulfuric acid to give Melon-B followed by oxidation with ozone and amination using ammonium hydroxide to give Melon-BO-NH_(2) or Triethylenetetramine(TETA)to give *** prepared biochars were characterized by BET,BJH,SEM,FT-IR,TGA,DSC and EDAX *** highest removal percentage of Cr(VI)ions was 69%for Melon-B,98%for Melon-BO-NH_(2) and 99%for Melon-BO-TETA biochars of 100 mg·L^(−1) Cr(VI)ions initial concentration and 1.0 g·L^(−1) adsorbents *** unmodified biochar(Melon-B)and modified biochars(Melon-BO-NH_(2) and Melon-BO-TETA)had maximum adsorption capacities(Q_(m))of 72.46,123.46,and 333.33 mg·g^(−1),*** amination of biochar reduced the pore size of modified biochar,whereas the surface area was *** obtained data of isotherm models were tested using different error function *** Freundlich,Tempkin and Langmuir isotherm models were best fitted to the experimental data of Melon-B,Melon-BO-NH_(2) and Melon-BO-TETA,*** adsorption rate was primarily controlled by pseudo-second–order rate ***,the functional groups interactions are important for adsorption mechanisms and expected to control the adsorption *** adsorption for the Melon-B,Melon-BO-NH_(2) and Melon-BO-TETA could be explained for acid–base interaction and hydrogen bonding interaction.

关键词： Waste treatment Powder technology Citrullus lanatus Hexavalent chromium Biochar amination Adsorption

3D FEM simulations and experimental validation of plastic deformation of pure aluminum deformed by ECAP and combination of ECAP and direct extrusion

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Transactions of Nonferrous Metals Society of China 2017年第6期27卷 1338-1352页

作者： mohamed Ibrahim abd el AAL Mechanical engineering Department College of Engineering Prince Sattam Bin Abdulaziz UniversityWadi Addawasir Kingdom of Saudi Arabia Mechanical Design & Production Department Faculty of Engineering Zagazig University Zagazig Egypt

Rigid-viscoplastic3D finite element simulations(3D FEM)of the equal channel angular pressing(ECAP),thecombination of ECAP+extrusion with different extrusion ratios,and direct extrusion of pure aluminum were performed ***3D FEM simulations were carried out to investigate the load-displacement behavior,the plastic deformationcharacteristics and the effective plastic strain homogeneity of Al-1080deformed by different forming *** simulationresults were validated by microstructure observations,microhardness distribution maps and the correlation between the effectiveplastic strain and the microhardness ***3D FEM simulations were performed successfully with a good agreement with theexperimental *** load-displacement curves and the peak load values of the3D FEM simulations and the experimentalresults were close from each *** microhardness distribution maps were in a good conformity with the effective plastic straincontours and verifying the3D FEM simulations *** ECAP workpiece has a higher degree of deformation homogeneity thanthe other deformation *** microhardness values were calculated based on the average effective plastic *** microhardness values fitted the experimental results *** microstructure observations in the longitudinal andtransverse directions support the3D FEM effective plastic strain and microhardness distributions result in different formingprocesses.

关键词： equal channel angular pressing (ECAP) extrusion finite element method (FEM) microhardness deformation homogeneity microstructure

Parameters Affecting Energy Consumption for Producing High Carbon Ferromanganese in a Closed Submerged Arc Furnace

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Journal of Iron and Steel Research International 2014年第7期21卷 666-672页

作者： Azza ahmed Hossam Halfa mohamed K.el-Fawakhry Hoda el-Faramawy Mamdouh Eissa Steel Technology Metallurgical Research and Development Institute

The power consumption is considered to be the most important factor affecting the production cost of fer romanganese alloy. Different parameters affecting the energy consumption for industrial production of high carbon ferromanganese HCFeMn were investigated in a closed submerged arc furnace. The analysis of industrial data revealed that the most energy consumed factors were the direct reduction by solid carbon, Boudouard reaction, metal and slag formation, and decomposition of fluxing materials （limestone and dolomite）. To reduce the energy con- sumption and minimize the energy losses in the production process of HCFeMn, it was recommended to use Mn blend with minimum Mn to Fe ratio of 6 and lower SiO2 content or higher basicity. The added coke must be adjusted according to the material balance to prevent the over-coke and to minimize the highly endothermic ＂Boudouard reac tion＂. In addition, it was recommended to work at basic slags with the ratio of （CaO＋MgO） to Si（）2 equal to 1.0- 1.2 instead of much higher slag basicity. Furthermore, the mass losses had to be minimized through adjusting the handling and charging process and to take care of all metal produced.

关键词： high carbon ferromanganese production energy consumption carbonate decomposition Boudouard reaction slag basicity energy loss

Training program for caregivers to prevent pressure ulcers among elderly residents at geriatric homes

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Frontiers of Nursing 2021年第3期8卷 249-259页

作者： Donia Atef Ibrahiem Mona mohamed abd el-Maksoud Community Health Nursing Faculty of NursingHelwan UniversityCairo 11571Egypt

Objectives:Pressure ulcer(PU)is one of the most common problem among the bedridden elderly and has significantly more burden on elderly and *** study is aimed to evaluate the effects of the training program for caregivers to prevent PUs among elderly residents at geriatric ***:A quasi-experimental design was used to carry out the current study.A purposive sample comprised of all formal(39 nurses)or informal caregivers(39)and all immobilized elderly residents(35)who are found in all geriatric centers in Helwan district.A structured questionnaire was used to assess caregivers’socio-demographic characteristics,knowledge,attitude,and observational checklists for their practice for prevention of PU at pre-and posttest and during ***:After the training program,there were improvements in the level of knowledge,practice,and positive attitude of caregivers about PU prevention with a statistically significant difference between pre-,post-,and follow-up training programs(Pelderly caregivers’attitudes as well as practice for prevention could be important in reducing the burden of PU among the ***,conducting a training program for caregivers at different geriatric homes about caring skills for elders can prevent PU,and using spontaneous reposition is very effective to prevent PUs.

关键词： caregivers elderly residents geriatric homes pressure ulcers training program

Low-voltage ride-through capability improvement of Type-3 wind turbine through active disturbance rejection feedback control-based dynamic voltage restorer

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Clean Energy 2023年第5期7卷 1091-1109页

作者： el Mahfoud Boulaoutaq Asma Aziz abdelmounime el Magri ahmed Abbou mohamed Ajaamoum Azeddine Rachdy Ibn Zohr University Higher School of Technology Agadir School of Engineering Edith Cowan UniversityJoondalupWAaustralia Hassan II University of Casablanca National School of Technical Education Mohammed V University of Rabat Mohammadia School of Engineering

Disconnections due to voltage drops in the grid cannot be permitted if wind turbines(WTs)contribute significantly to electricity pro-duction,as this increases the risk of production loss and destabilizes the *** mitigate the negative effects of these occurrences,WTs must be able to ride through the low-voltage conditions and inject reactive current to provide dynamic voltage *** paper investigates the low-voltage ride-through(LVRT)capability enhancement of a Type-3 WT utilizing a dynamic voltage restorer(DVR).During the grid voltage drop,the DVR quickly injects a compensating voltage to keep the stator voltage *** paper proposes an active disturbance rejection control(ADRC)scheme to control the rotor-side,grid-side and DVR-side converters in a wind–DVR integrated *** performance of the Type-3 WT with DVR topology is evaluated under various test conditions using MATLAB®/Simulink®.These simulation results are also compared with the experimental results for the LVRT capability performed on a WT emulator equipped with a crowbar and direct current(DC)*** simulation results demonstrate a favourable transient and steady-state response of the Type-3 wind turbine quantities defined by the LVRT codes,as well as improved reactive power support under balanced fault *** the most severe voltage drop of 95%,the stator currents,rotor currents and DC bus voltage are 1.25 pu,1.40 pu and 1.09 UDC,respectively,conforming to the values of the LVRT *** controlled by the ADRC technique significantly increases the LVRT capabilities of a Type-3 doubly-fed induction generator-based WT under symmetrical voltage dip *** setting up ADRC controllers might be challenging,the proposed method has been shown to be extremely effective in reducing all kinds of internal and external disturbances.

关键词： active disturbance rejection controller(ADRC) dynamic voltage restorer(DVR) low-voltage ride-through(LVRT) Type-3 wind turbines(WTs) doubly-fed induction generator(DFIG)