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REFLECTION CHARACTERISTICS OF LONGITUDINAL WAVES IN A SEmI-INFINITE CYLINDRICAL ROD CONNECTED TO AN INFINITE VISCOELASTIC STRATUm

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Acta mechanica Solida Sinica 1996年第1期9卷 66-80页

作者： A.moussa S.Bichir m.nassar Department of Engineering mathematics and Physics Faculty of EngineeringCairo UniversityGizaEgypt

Reflection characteristics of longitudinal strain waves in a semi-infinite elastic rod con- nected to a viscoelastic stratum are investigated *** three-dimensional viscoelasticity the- ory is applied to the stratum,and the Laplace transform with respect to time and the numerical inverse Laplace transform by means of Laguerre function are *** time histories for the longitudinal strain of an arbitrary point of the rod are *** typical viscoelastic models are considered, one is the usual maxwell-Voigt model,the other is whose relaxation function is given by a power law. The numerical results for the two models are presented and compared each other and also with previ- ously published results for the elastic stratum.

关键词： viscoelastic stratum Laplace transform

Antimicrobial properties of dental cements modified with zein-coated magnesium oxide nanoparticles

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Bioactive materials 2022年第2期7卷 49-56页

作者： Ghada H.Naguib Hani m.nassar mohamed T.Hamed Department of Restorative Dentistry Faculty of DentistryKing Abdulaziz UniversityJeddahSaudi Arabia Department of Oral Biology Faculty of DentistryCairo UniversityCairoEgypt Department of Oral and maxillofacial Prosthodontics King Abdulaziz UniversityFaculty of DentistryJeddahSaudi Arabia Department of Fixed Prosthodontics Faculty of DentistryCairo UniversityCairoEgypt

The aim of this study was to test the antimicrobial properties of dental cements modified with magnesium oxide(mgO)***-modified mgO nanoparticles(zmgO)in concentrations(0.0,0.3,0.5,and 1.0%)were mixed with dental cements(Fuji II,Rely X Temp E,Ionoglass Cem,Es Temp NE,and System P link).Eight discs were fabricated from each zmgO-cement pair for a total of 32 specimens for each *** of the dental cements incorporating zmgO was done by X-ray Diffraction(XRD)and Field Emission Scanning Electron microscopy(FESEm).The antimicrobial properties of the mixtures were tested using direct contact and agar diffusion assays against Streptococcus mutans,Staphylococcus aureus,Enterococcus faecalis,and Candida *** was analyzed using two-way analysis of variance and LSD post hoc test at 0.05 significance *** spectra showed sharp peaks of zmgO indicating its high crystalline nature,while the amorphous dental cements with zmgO had broad *** analysis showed a uniform distribution of the zmgO nanoparticles in the *** were significant inhibition zone values associated with all concentrations of zmgO-cement mixtures tested compared to controls(pmgO groups compared to controls for all *** effect was most prominent with Rely X against *** and *** cements containing zmgO showed significant antimicrobial properties that were dependent on the specific initial cement substrate.

关键词： magnesium oxide nanoparticles Antimicrobial biomaterials Dental cement Nanocoatings

An Invasive Succulent Plant (Kalanchoe daigremontiana) Influences Soil Carbon and Nitrogen mineralization in a Neotropical Semiarid Zone

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Pedosphere 2018年第4期28卷 632-643页

作者： Ileana HERRERA Jose R. FERRER-PARIS Diana BENZO Saul FLORES Belkis GARCIA Jafet m. nassar Ecuela de Ciencias Ambientales Universidad Espiritu Santo Guayaquil 091650 (Ecuador) Centro de Ecologla Instituto Venezolano de Investigaciones Cientificas (IVIC) Caracas 1020 (Venezuela) Centro de Estudios Botdnieos y Agroforestales Instituto Venezolano de Investigaeiones Cientificas Maracaibo 4005 (Venezuela)

It has long been recognized that plant invasions may alter carbon （C） and nitrogen （N） cycles, but the direction and magnitude of such alterations have been rarely quantified. In this study, we quantified the effects caused by the invasion of a noxious exotic plant, Kalanchoe daigrernontiana （Crassulaceae）, on C and N mineralization and enzymatic and microbial activities in the soil of a semiarid locality in Venezuela. We compared soil parameters associated with these processes （C and N mineralization time and the cumulative values, fluorescein diacetate hydrolytic activity, and activities of dehydrogenase, β-glucosidase, glucosaminidase, and urease） between invaded and adjacent non-invaded sites. In addition, correlations among these parameters and the soil physical-chemical properties were also examined to determine if a positive feedback exists between nutrient availability and K. daigremontiana invasion. Overall, our results showed that C mineralization and transformation of organic compounds to NH4^＋ were favored at sites colonized by K. daigrernontiana. With this species, we found the highest cumulative amounts of NH4^＋-N and C and the lowest mineralization time. These results could be explained by higher activities of urease and glueosaminidase in soils under the influence of K. daigremontiana. In addition, higher amounts of organic matter and moisture content in invaded soils might favor C and N mineralization. In conclusion, invasion of Neotropical semiarid zones by K. daigrernontiana may influence the chemical and biological properties of the soils covered by this species, increasing nutrient bioavailability, which, in time, can facilitate the invasion process.

关键词： Akaike Information Criterion C and N pools enzymatic activity NH4^+-N NO3^--N nutrient availability plant invasion

Compliant plant wearables for localized microclimate and plant growth monitoring

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npj Flexible Electronics 2018年第1期2卷 219-230页

作者： Joanna m.nassar Sherjeel m.Khan Diego Rosas Villalva maha m.Nour Amani S.Almuslem muhammad m.Hussain mmh Labs Electrical EngineeringComputer Electrical Mathematical Science and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia

The microclimate surrounding a plant has major effect on its health and photosynthesis process,where certain plants struggle in suboptimal environmental conditions and unbalanced levels of humidity and *** ability to remotely track and correlate the effect of local environmental conditions on the healthy growth of plants can have great impact for increasing survival rate of plants and augmenting agriculture *** necessitates the widespread distribution of lightweight sensory devices on the surface of each *** flexible and biocompatible materials coupled with a smart compact design for a low power and lightweight system,we develop widely deployed,autonomous,and compliant wearables for *** demonstrated wearables integrate temperature,humidity and strain sensors,and can be intimately deployed on the soft surface of any plant to remotely and continuously evaluate optimal growth *** is enabled through simultaneous detection of environmental conditions while quantitatively tracking the growth rate(***).Finally,we establish a nature-inspired origami-assembled 3D-printed“PlantCopter”,used as a launching platform for our plant wearable to enable widespread microclimate monitoring in large fields.

关键词： humidity microclimate autonomous

Compliant lightweight non-invasive standalone“marine Skin”tagging system

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npj Flexible Electronics 2018年第1期2卷 97-105页

作者： Joanna m.nassar Sherjeel m.Khan Seneca J.Velling Andrea Diaz-Gaxiola Sohail F.Shaikh Nathan R.Geraldi Galo A.Torres Sevilla Carlos m.Duarte muhammad m.Hussain mmh Labs Computer Electrical Mathematical Science and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia material&Nanoscience Program Faculty of ScienceUniversity of WaterlooWaterlooON N2L-3G1Canada Red Sea Research Center(RSRC) Biological and Environmental Sciences and Engineering(BESE)DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia

Current marine research primarily depends on weighty and invasive sensory equipment and telemetric network to understand the marine environment,including the diverse fauna it contains,as a function of animal behavior and size,as well as equipment *** match animal morphology and activity within the surrounding marine environment,here we show a physically flexible and stretchable skin-like and waterproof autonomous multifunctional system,integrating Bluetooth,memory chip,and high performance physical *** sensory tag is mounted on a swimming crab(Portunus pelagicus)and is capable of continuous logging of depth,temperature,and salinity within the harsh ocean *** fully packaged,ultra-lightweight(mpliant“marine Skin”system does not have any wired connection enabling safe and weightless cuttingedge approach to monitor and assess marine life and the ecosystem’s health to support conservation and management of marine ecosystems.

关键词： marine system Skin

Thermobonding of Wool Nonwovens

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Thermobonding of Wool Nonwovens

Flexible and biocompatible high-performance solid-state micro-battery for implantable orthodontic system

第二届先进纺织材料及加工技术国际会议

作者： K.m.nassar I.Porat Textiles and Paper School of MaterialsUniversity of ManchesterUK

Due to the low surface of wool fibres it is difficult to bond wool *** overcome this problem,different surface treatments were applied to the wool fibres to raise their surface *** were chlorination,hercosett and plasma *** melting nylon fibres were blended with the wool to provide the *** was shown that wool and nylon fibres can be thermally bonded to provide a light-weight and high-loft nonwoven structure with superior thermal insulation *** the three treatments,hercosett treated wool fibres yielded the strongest bonds.

关键词： Nonwoven Thermal bonding Wool Hercosett Plasma Chlorination

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npj Flexible Electronics 2017年第1期1卷 70-77页

作者： Arwa T.Kutbee Rabab R.Bahabry Kholod O.Alamoudi mohamed T.Ghoneim marlon D.Cordero Amani S.Almuslem Abdurrahman Gumus Elhadj m.Diallo Joanna m.nassar Aftab m.Hussain Niveen m.Khashab muhammad m.Hussain Integrated Nanotechnology Lab and Integrated Disruptive Electronic Applications(IDEA)Lab Material Science and EngineeringPhysical Science and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia Khashab Research Group Chemical SciencePhysical Science and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia Integrated Nanotechnology Lab and Integrated Disruptive Electronic Applications(IDEA)Lab Electrical EngineeringComputer Electrical and Mathematical Sciences and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia Integrated Nanotechnology Lab and Integrated Disruptive Electronic Applications(IDEA)Lab Mechanical EngineeringPhysical Science and Engineering DivisionKing Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia KAUST Nanofabrication Core Lab King Abdullah University of Science and Technology(KAUST)Thuwal 23955-6900Saudi Arabia

To augment the quality of our life,fully compliant personalized advanced health-care electronic system is *** of the major requirements to implement such systems is a physically flexible high-performance biocompatible energy storage(battery).However,the status-quo options do not match all of these attributes simultaneously and we also lack in an effective integration strategy to integrate them in complex architecture such as orthodontic domain in human *** we show,a physically complaint lithium-ion micro-battery(236μg)with an unprecedented volumetric energy(the ratio of energy to device geometrical size)of 200 mWh/cm^(3) after 120 cycles of continuous *** results of 90%viability test confirmed the battery’s *** also show seamless integration of the developed battery in an optoelectronic system embedded in a threedimensional printed smart dental *** foresee the resultant orthodontic system as a personalized advanced health-care application,which could serve in faster bone regeneration and enhanced enamel health-care protection and subsequently reducing the overall health-care cost.

关键词： battery system performance

应用局部放电和冲击电压试验鉴别大型电动机匝间绝缘故障

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四川电力技术 1991年第4期14卷 52-56页

作者： O.m.nassar 石松

13.2kV、21000HP的几台同步电动机发生匝间绝缘击穿故障。电动机故障研究表明,其原因与高幅值陡峭波前的冲击波有关,与故障有关的局部放电(电晕)被忽视未进行实测。为证实上述研究的有效性,在4台新的21000HP电动机和一台已发生故障的210... 详细信息

13.2kV、21000HP的几台同步电动机发生匝间绝缘击穿故障。电动机故障研究表明,其原因与高幅值陡峭波前的冲击波有关,与故障有关的局部放电(电晕)被忽视未进行实测。为证实上述研究的有效性,在4台新的21000HP电动机和一台已发生故障的21000HP电动机上进行了局部放电试验。此外,在这台故障的电动机上还进行了冲击电压试验,以评定匝间绝缘的寿命。本文提供了上述试验的结果,并得出结论,这些电动机的故障不是由电晕引起。目前已被证实的研究结果指出,局部放电试验能够作为诊断大型电动机匝间绝缘的一种方法。

关键词：电动机故障局部放电冲击电压

Towards rational use of drugs in Egypt

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Towards rational use of drugs in Egypt