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Three-dimensional printing of biomaterials for bonetissue engineering: a review

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Frontiers of Materials Science 2023年第2期17卷 1-43页

作者： ahmed el-Fiqi Glass Research Department Advanced Materials Technology and Mineral Resources Research InstituteNational Research CentreCairo 12622Egypt

Processing biomaterials into porous scaffolds for bone tissueengineering is a critical and a key step in defining and controlling their physicochemical,mechanical,and biological *** such as polymers are commonlyprocessed into porous scaffolds using conventional processing techniques,e.g.,***,these traditional techniques have shown unavoidable limitations andseveral *** instance,tissue-engineered porous scaffolds with a complexthree-dimensional(3D)geometric architecture mimicking the complexity of theextracellular matrix of native tissues and with the ability to fit into irregular tissue defectscannot be produced using the conventional processing techniques.3D printing hasrecently emerged as an advanced processing technology that enables the processing ofbiomaterials into 3D porous scaffolds with highly complex architectures and tunableshapes to precisely fit into irregular and complex tissue defects.3D printing providescomputer-based layer-by-layer additive manufacturing processes of highly precise andcomplex 3D structures with well-defined porosity and controlled mechanical propertiesin a highly reproducible ***,3D printing technology provides anaccurate patient-specific tissue defect model and enables the fabrication of a patientspecifictissue-engineered porous scaffold with pre-customized properties.

关键词： 3D printing biomaterial ink printability 3D printing technique 3D printed scaffold bone tissue engineering

LEO satellite clock analysis and prediction for positioning applications

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Geo-Spatial Information Science 2022年第1期25卷 14-33页

作者： Kan Wang ahmed el-Mowafy School of Earth and Planetary Sciences Curtin UniversityPerthAustralia

The positioning service aided by low Earth orbit(LEO)mega-constellations has become a hot topic in recent *** achieve precise positioning,accuracy of the LEO clocks is important for single-receiver *** bridge the gap between the applicable time of the clock products and the time of positioning,the precise LEO clocks need to be predicted over a certain period depending on the sampling interval of the clock *** study discusses the prediction errors for periods from 10 s to 1 h for two typical LEO clock types,*** ultra-stable oscillator(USO)and the oven-controlled crystal oscillator(OCXO).The prediction is based on GNSS-determined precise clock estimates,where the clock stability is related to the GNSS estimation errors,the behaviors of the oscillators themselves,the systematic effects related to the environment and the relativistic effects,and the stability of the time *** on real data analysis,LEO clocks of the two different types are simulated under different conditions,and a prediction model considering the systematic effects is *** to a simple polynomial fitting model usually applied,the proposed model can significantly reduce the prediction errors,*** about 40%-70%in simulations and about 5%-30%for real data containing different miss-modeled *** both clock types,short-term prediction of 1 min would result in a root mean square error(RMSE)of a few centimeters when using a very stable time *** RMSE amounts to about 0.1 m,when a typical real-time time reference of the national center for space studies(CNES)real-time clocks was *** long-term prediction of 1 h,the RMSE could range from below 1 m to a few meters for the USOs,depending on the complexity of the miss-modeled *** OCXOs,the 1 h prediction could lead to larger errors with an RMSE of about 10 m.

关键词： LEO clock prediction USO OCXO relativistic effects

Magnetoresistive properties of Ni-doped La_(0.7)Sr_(0.3)MnO_3 manganites

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Rare Metals 2016年第7期35卷 551-558页

作者： ahmed Mohamed ahmed Abd el-Moez ahmed Mohamed Medhat Abdelrady Abdellateef Hassan ahmed Abd el-Ghanny Physics Department Faculty of ScienceSohag University

Lao.7Sr0.3Mnl_xNixO3 （x = 0, 0.025, 0.050 and 0.075） ceramics were prepared by the conventional solid-state reaction method. The partial substitution of Mn by Ni2＋ leads to a decrease in cell volume as well as a structural transition from the rhombohedral to the orthorhombic structure. Ni2＋ doping increases the electrical resistivity, decreases the semiconductor-metal transition temperature （Tms） and relatively enhances the room temperature magnetoresistance （MR）, especially in x = 0.025 and around Tins. With respect to conduction mechanism, the small polaron hopping （SPH） and the variable range hopping （VRH） models were used to ex- amine conduction in the semiconducting region.

关键词： Manganites X-ray diffraction Structure electrical resistivity Magnetoresistance

Current approaches in treatment of triple-negative breast cancer

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Cancer Biology & Medicine 2015年第2期12卷 106-116页

作者： Hanan ahmed Wahba Hend ahmed el-Hadaad Clinical Oncology and Nuclear Medicine Mansoura University

Triple-negative breast cancer(TNBC) is diagnosed more frequently in younger and premenopausal women and is highly prevalent in African American women. TNBC is a term derived from tumors that are characterized by the absence of ER, Pg R, and HER2. So patients with TNBC do not benefit from hormonal or trastuzumab-based therapies. TNBCs are biologically aggressive, although some reports suggest that they respond to chemotherapy better than other types of breast cancer, prognosis remains poor. This is due to: shortened disease-free interval in the adjuvant and neoadjuvant setting and a more aggressive course in the metastatic setting.

关键词： Breast cancer triple-negative HER2

Efficacy of octreotide in the prevention of complications after pancreaticoduodenectomy in patients with soft pancreas and non-dilated pancreatic duct: A prospective randomized trial

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Hepatobiliary & Pancreatic Diseases International 2018年第1期17卷 59-63页

作者： Ayman el Nakeeb ahmed el Gawalby Mahmoud A.Ali ahmed Shehta Hosam Hamed Mohamed el Refea ahmed Moneer ahmed Abd el Rafee Gastroenterology Surgical Center Mansoura University

Background: The efficacy of octreotide to prevent postoperative pancreatic fistula(POPF) of pancreaticoduodenectomy(PD) is still controversial. This study aimed to evaluate the effect of postoperative use of octreotide on the outcomes after ***: This is a prospective randomized controlled trial for postoperative use of octreotide in patients undergoing PD. Patients with soft pancreas and pancreatic duct elayed gastric emptying(P = 0.472), and early postoperative mortality(P = 0.727).Conclusions: Octreotide did not reduce postoperative morbidities, reoperation and mortality rate. Also, it did not affect the incidence of POPF and its clinically relevant variants.

关键词： Pancreaticoduodenectomy Postoperative pancreatic fistula Octreotide Periampullary tumor

Experimental and numerical investigation of the abrasive waterjet machining of aluminum-7075-T6 for aerospace applications

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Advances in Manufacturing 2021年第2期9卷 286-303页

作者： Joseck Nyaboro Mahmoud ahmed Hassan el-Hofy Mohamed el-Hofy Department of Industrial and Manufacturing Engineering Egypt-Japan University of Science and Technology(E-JUST)Alexandria 21934Egypt Department of Energy Resources Engineering Egypt-Japan University of Science and Technology(E-JUST)Alexandria 21934Egypt Advanced Manufacturing Research Centre(AMRC)with Boeing The University of SheffieldRotherham S605TZUK

The machining of hard-to-cut materials with a high degree of precision and high surface quality is one of the most critical considerations when fabricating various state-of-the-art engineered *** this investigation,a comprehensive three-dimensional model was developed and numerically simulated to predict kerf profiles and material removal rates while drilling the aluminum-7075-T6 aerospace *** profile and material removal prediction involved three stages:jet dynamic flow modeling,abrasive particle tracking,and erosion rate *** investigations were conducted to validate the developed *** results indicate that the jet dynamic characteristics and flow of abrasive particles alter the kerf profiles,where the top kerf diameter increases with increasing jet pressure and standoff *** kerf depth and hole aspect ratio increase with jet pressure,but decrease with standoff distance and machining *** profiles were characterized by progressive edge rounding and parabolic *** can be minimized by utilizing high jet pressure and small standoff *** material removal rate increases with increasing jet pressure,abrasive particle size,and exposure time,but decreases with increasing standoff distance.

关键词： Non-traditional machining Abrasive waterjet machining Computational fluid dynamics(CFD) Erosion modeling Kerf characteristics

Inertial sensors technologies for navigation applications:state of the art and future trends

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Satellite Navigation 2020年第1期1卷 9-29页

作者： Naser el-Sheimy ahmed Youssef Mobile Multi-sensor Systems Research Team Department of Geomatics EngineeringUniversity of Calgary2500 University Drive N.WCalgaryAB T2N 1N4Canada

Inertial navigation represents a unique method of navigation,in which there is no dependency on external sources of *** opposed to other position fixing navigation techniques,inertial navigation performs the navigation in a relative sense with respect to the initial navigation state of the moving ***,inertial navigation systems are not prone to jamming,or *** navigation systems have developed vastly,from their occurrence in the 1940s up to *** accuracy of the inertial sensors has improved over time,making inertial sensors sufficient in terms of size,weight,cost,and accuracy for navigation and guidance *** the past few years,inertial sensors have developed from being purely mechanical into incorporating various technologies and taking advantage of numerous physical phenomena,from which the dynamic forces exerted on a moving body could be computed ***,the evolution of inertial navigation scheme involved the evolution from stable-platform inertial navigation system,which were mechanically complicated,to computationally demanding strap-down inertial navigation *** sensory technologies have provided highly accurate inertial sensors,at smaller ***,the vibratory inertial navigation technologies enabled the production of Micro-electro-machined inertial sensors that are extremely low-cost,and offer extremely low size,weight and power consumption,making them suitable for a wide range of day-to-day navigation ***,advanced inertial sensor technologies have been introduced to the industry such as nuclear magnetic resonance technology,coldatom technology,and the reintroduction of fluid-based inertial *** another note,inertial sensor errors constitute a huge research aspect in which it is intended for inertial sensors to reach level in which they could operate for substantially long operation times in the absence of updates from aiding sensors,which would be a hug

关键词： Gyroscopes Accelerometers Optical inertial sensors Micro-electro-machined Fluid-based inertial sensors Stochastic modeling

Recovery of some valuable elements from lamprophyre dykes in the Abu Rusheid area, Southeastern Desert, Egypt

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Chinese Journal Of Geochemistry 2012年第1期31卷 64-73页

作者： Zaki D.I. Shawky N. el-sheikh E.M. ahmed F.Y. Ibrahim M.E. Nuclear Materials Authority El MaadiP.O.Box 530 CairoEgypt Chemistry Dept. Faculty of Science for GirlAl-Azhar UniversityEgypt

In the Abu Rusheid area, Southeastern Desert of Egypt, polymineralized (HREEs, U, Zn and Pb) lam-prophyre dykes are recently recorded. The lamprophyre dykes cut cataclastic rocks along share zones in NNW-SSE trends. The secondary U-minerals are essentially represented by uranophane, kasolite, torbernite and autunite. Ex-perimental work was carried out on the lamprophyre dykes for the recovery of uranium and other valuable elements (e.g. Zn, Pb and Al) from 50 kg of technological sample. The optimum conditions were: 100 g/L sulfuric acid con-centration, 1:5 S/L (solid/liquid) and soaking for 15 days at room temperature. The leaching efficiencies for the re-covery of uranium and other elements like Al, Zn and Pb were 40, 33.6, 98.8 and 78, respectively.

关键词：有价元素煌斑岩岩脉沙漠埃及价值最佳工艺条件实验工作

Impacts of climate change on water quantity, water salinity, food security, and socioeconomy in Egypt

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Water Science and Engineering 2021年第1期14卷 17-27页

作者： Mohie el Din Mohamed Omar ahmed Moustafa ahmed Moussa Reinhard Hinkelmann National Water Research Center Fum Ismailiya CanalShoubra El-Kheima 13411Egypt International Center for Agricultural Research in the Dry Areas Cairo 2416Egypt Nile Research Institute(NRI) National Water Research CenterEl-Qanater 13621Egypt Department of Water Engineering Technische Universit€at Berlin(TU Berlin)Campus El GounaEl Gouna 84513Egypt

Climate change might have direct impacts on water quantity in Egypt and lead to indirect effects on Mediterranean saltwater intrusion to groundwater,which exposes agriculture to *** study investigated impacts of climate change on agriculture,with particular regard to food security and socioeconomy,and quantified the effectiveness of cropping pattern adaptation measures by integrating three mathematical *** BlueM model was used for hydrological simulations of Nasser Lake under flooding scenarios to predict the water supply from the High Aswan *** water and salinity balance(WB-SAL)model was adopted to estimate the water salinity in the Nile *** simulated results from the BlueM and WB-SAL models were integrated with the agricultural simulation model for Egypt(ASME)to project cropping patterns,food security,and socioeconomy throughout the *** results showed that future climate change will directly affect the total crop area;crop areas for 13 crop types;the self-sufficiency of wheat,rice,cereal,and maize supplies;and socioeconomic *** proposed cropping pattern adaptation measures focus on fixing the crop areas of rice and orchards and providing half of the population with lentils,maize,onion,vegetables,milk,and *** adaptation measures have the potential to promote food security without causing deterioration of the socioeconomic ***,water availability has much more significant effects on food security and socioeconomy than cropping pattern adaptation measures ***,the country should rationalize water use efficiency and increase water supply.©2021 Hohai *** and hosting by elsevier *** is an open access article under the CC BY-NC-ND license(http://***/licenses/by-nc-nd/4.0/).

关键词： Climate change Water quantity Salinity Cropping pattern adaptation measures Food security Socioeconomy