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Artigos de revistas sobre o assunto "MgO nanoparticule"
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ÖZGÜR, Tayfun, Erdi TOSUN, Ceyla ÖZGÜR, Gökhan TÜCCAR e Kadir AYDIN. "EFFECT OF MgO NANOPARTICULE ADDITIVES ON PERFORMANCE AND EXHAUST EMMISSIONS OF DIESEL FUELLED COMPRESSION IGNITION ENGINE". MATTER: International Journal of Science and Technology 3, n.º 3 (17 de novembro de 2017): 72–85. http://dx.doi.org/10.20319/mijst.2017.32.7285.
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ÖZGÜR, Tayfun, Erdi TOSUN, Ceyla ÖZGÜR, Gökhan TÜCCAR e Kadir AYDIN. "EFFECT OF MgO NANOPARTICULE ADDITIVES ON PERFORMANCE AND EXHAUST EMMISSIONS OF DIESEL FUELLED COMPRESSION IGNITION ENGINE". MATTER: International Journal of Science and Technology 3, n.º 3 (17 de novembro de 2017): 72–85. http://dx.doi.org/10.20319/mijst.2017.33.7285.
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Shaukat, Arslan, Ghulam Hussain, Shahzad Irfan, Muhammad Umar Ijaz e Haseeb Anwar. "Therapeutic Potential of MgO and MnO Nanoparticles Within the Context of Thyroid Profile and Pancreatic Histology in a Diabetic Rat Model". Dose-Response 20, n.º 3 (julho de 2022): 155932582211287. http://dx.doi.org/10.1177/15593258221128743.
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Magnesium oxide (MgO) and manganese oxide (MnO) have been reported to be effective against Diabetes Mellitus (DM). However, their nanoparticulate form has not been evaluated for antidiabetic effect. MgO and MnO nanoparticles (15–35 nm) were synthesized and subsequently characterized by ultraviolet-visible spectroscopy (UV-VIS), zeta sizer, and scanning electron microscopy. 6–7 weeks old rats weighing 200–220 mg were divided into 07 equal groups (n = 8), namely, negative control (NC), positive control (PC), standard control (Std-C), MgO high dose group (MgO-300) and low dose group (MgO-150), and MnO nanoparticle high dose (MnO-30) and low dose group (MnO-15). Diabetes was chemically induced (streptozotocin 60 mg/kg B.W) in all groups except the NC. Animals were given CMD and water was ad libitum. Nanoparticles were supplemented for 30 days after the successful induction of diabetes. Blood and tissue samples were collected after the 30th day of the trial. The mean serum glucose, insulin, and glucagon levels were improved maximally in the MgO-300 group followed by MgO-150 and MnO-30 groups. Whereas the MnO-15 group fails to show any substantial improvement in the levels of glucose, insulin, and glucagon as compared to the positive control group. Interesting the serum triiodothyronine, thyroxine, and thyroid-stimulating hormone levels were markedly improved in all the nanoparticle treatment groups and were found to be similar to the standard control group. These results highlight the modulatory properties of MgO and MnO nanoparticles and merit further studies delineating the molecular mechanisms through which these nanoparticles induce antidiabetic effects.
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Hasbullah, N. I., Mat Zain Mazatulikhma e N. Kamarulzaman. "Nanotoxicity of Magnesium Oxide on Human Neuroblastoma SH-SY5Y Cell Lines". Advanced Materials Research 667 (março de 2013): 160–64. http://dx.doi.org/10.4028/www.scientific.net/amr.667.160.
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The use of magnesium oxide (MgO) nanoparticles in industrial applications has been raised over the last decade. However, there is limited toxicology information available regarding the effects of MgO nanoparticles. In this study, cytotoxicity and neurotoxicity of this nanoparticle on SH-SY5Y cell lines was investigated. In order to assess the cytotoxicity effect, SH-SY5Y cells were exposed to three different types of MgO nanoparticles (MgO 5, MgO 10 and MgO 24) for 24, 48 and 72 h. The concentration of nanoparticles ranges from 1nM to 1mM. Cell viability was determined by MTS assay. Neurotoxicity test was performed to determine the effects of MgO nanoparticles on human neural cells. Results indicated that MgO nanoparticles are not toxic to both undifferentiated and differentiated SH-SY5Y cells. With further exploration, the safety and health concern regarding exposure of MgO nanoparticles can be verified since the increasing of using this nanoparticle in industry over the time.
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Sanjurjo-García, José Angel, Pablo Samuel Schabes-Retchkiman, Ma Guadalupe Macedo, José Luis García-Rivas, Javier Illescas e Sonia Martínez-Gallegos. "Influence of the metal concentration on the phytosynthesis of nanoparticles of Iron and Zinc". MRS Advances 4, n.º 59-60 (2019): 3207–13. http://dx.doi.org/10.1557/adv.2019.473.
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ABSTRACTIn this work, green nanotechnology has been applied by using phytochemical compounds as reducing agents from the plant extract of Hydrocotyle ranunuculoides through three modifications of the phytosynthesis method to prepare Fe and Zn nanoparticles, in three different concentration of the metallic solution. In the third modification a MgO support was included to avoid the Fe and Zn NP agglomeration. The nanoparticles size was 5±1 nm, and for the Fe NPs, it was determined with a cubic structure a Fe3O4 composition, and Zn nanoparticles were obtained with a hexagonal structure and Zn° composition. In the third method, MgO nanoparticle, the support appears as Mg0 nanoparticles surrounded by Fe0 and Zn0 nanoparticles. According to the three used methods pathways, the main influence is the modification in the method synthesis. Hybrid nanocomposites provide a means in preventing agglomeration of the NPs and hence avoid coalescence and loss of properties.
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Leizou, Kaywood Elijah, e Muhammad Aqeel Ashraf. "GREEN SYNTHESIS APPROACH, CHARACTERIZATION, AND APPLICATIONS OF MgO NANO PARTICLES USING CURRY LEAF (MURRAYA KOENIGII)". Acta Scientifica Malaysia 6, n.º 1 (2022): 06–09. http://dx.doi.org/10.26480/asm.01.2022.06.09.
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Nanotechnology has emerged as a state-of-the-art and cutting-edge technology with multifarious applications in a wide array of fields. The goal of this study was to create magnesium oxide nanoparticles using an aqueous extract of curry leaves (murraya koenigii or bergera koenigii). The morphology, elemental content, shape, and size of the produced MgO nanoparticles were determined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy analysis (EDX). According to the SEM data, the MgO nanoparticle forms were well disseminated, with a spherical shape and particle sizes ranging from 20 to 100 nm. While the EDX pattern infers the sample’s elemental composition, the average occurrence of Mg was 32.45 percent. Plant extracts were used to successfully produce MgO nanoparticlse, which is an essential alternative technique because it is non-toxic, biocompatible, and environmentally benign.
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Faisal, Shah, Abdullah, Hasnain Jan, Sajjad Ali Shah, Sumaira Shah, Muhammad ad Rizwan, Nasib Zaman et al. "Bio-Catalytic Activity of Novel Mentha arvensis Intervened Biocompatible Magnesium Oxide Nanomaterials". Catalysts 11, n.º 7 (27 de junho de 2021): 780. http://dx.doi.org/10.3390/catal11070780.
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In the present study Mentha arvensis medaited Magnesium oxide nanoparticles were synthesized by novel green route followed by advanced characterization via XRD, FTIR, UV, SEM, TEM, DLS and TGA. The mean grain size of 32.4 nm and crystallite fcc morphology were confirmed by X-ray diffractive analysis. Scanning and Transmission electron microscopy analysis revealed the spherical and elliptical morphologies of the biosynthesized nanoparticles. Particle surface charge of −16.1 mV were determined by zeta potential and zeta size of 30–120 nm via dynamic light scattering method. Fourier transform spectroscopic analysis revealed the possible involvement of functional groups in the plant extract in reduction of Mg2+ ions to Mg0. Furthermore, the antioxidant, anti-Alzheimer, anti-cancer, and anti-H. pylori activities were performed. The results revealed that MgO-NPs has significant anti-H. pyloric potential by giving ZOI of 17.19 ± 0.83 mm against Helicobacter felis followed by Helicobacter suis. MgO-NPs inhibited protein kinase enzyme up to 12.44 ± 0.72% at 5 mg/mL and thus showed eminent anticancer activity. Significant free radicals scavenging and hemocompatability was also shown by MgO-NPs. MgO-NPs also displayed good inhibition potential against Hela cell lines with maximum inhibition of 49.49 ± 1.18 at 400 µg/mL. Owing to ecofriendly synthesis, non-toxic and biocompatible nature, Mentha arvensis synthesized MgO-NPs can be used as potent antimicrobial agent in therapeutic applications.
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Pradheesh, G., J. Suresh, S. Suresh, Kumar P. Satheesh e Vincent Alexramani. "Biosynthesis of MgO nanoparticles and Bioactivity studies on the medicinal plant Cyathea nilgirensis Holttum". Research Journal of Chemistry and Environment 26, n.º 9 (25 de agosto de 2022): 64–72. http://dx.doi.org/10.25303/2609rjce064072.
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Plant secondary metabolites play a major role in biosynthesis of nanoparticles. As a new approach, we have used aqueous ethanolic extract of Cyathea nilgirensis Holttum to synthesize MgO nanoparticles by chemical precipitation method. FT-IR spectroscopy studies have proved that biomolecules have acted as stabilizing agents in the synthesis of MgO nanoparticle. SEM analysis has exhibited the morphological appearance of MgO nanoparticles. Energy Dispersive X-Ray analysis has proved the presence of both magnesium and oxygen in the synthesized MgO nanoparticles. The fungal species A. niger is observed to have remarkably higher percentage of inhibition (71.4%). The results of cancer studies suggest that as concentration increases from 10 μg to 200 μg, the percentage of inhibition of MgO nanoparticles increases. Thus plant extract mediated MgO nanoparticles have proven to be a better antimicrobial and anticancer agent.
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Photiphitak, Chanu, Pattana Rakkwamsuk, Pennapa Muthitamongkol e Chanchana Thanachayanont. "A Combined Effect of Plasmon Energy Transfer and Recombination Barrier in a Novel TiO2/MgO/Ag Working Electrode for Dye-Sensitized Solar Cells". International Journal of Photoenergy 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/795138.
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Novel TiO2/MgO/Ag composite electrodes were applied as working electrodes of dye-sensitized solar cells (DSSCs). The TiO2/MgO/Ag composite films were prepared by dip coating method for MgO thin films and photoreduction method for Ag nanoparticles. The MgO film thicknesses and the Ag nanoparticle sizes were in ranges of 0.08–0.46 nm and 4.4–38.6 nm, respectively. The TiO2/MgO/Ag composite films were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The TiO2/MgO/Ag composite electrodes were sensitized by immersing in a 0.3 mM of N719 dye solution and fabricated for conventional DSSCs.J-Vcharacteristics of the TiO2/MgO/Ag DSSCs showed that the MgO film thickness of 0.1 nm and the Ag nanoparticle size of 4.4 nm resulted in maximum short circuit current density and efficiency of 8.6 mA/cm2and 5.2%, respectively. Electrochemical Impedance Spectroscopy showed that such values of short circuit current density and efficiency were optimal values obtained from plasmon energy transfer by 4.4 nm Ag nanoparticles and recombination barrier by the ultrathin MgO film.
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Fatiqin, A., H. Amrulloh e W. Simanjuntak. "Green synthesis of MgO nanoparticles using Moringa oleifera leaf aqueous extract for antibacterial activity". Bulletin of the Chemical Society of Ethiopia 35, n.º 1 (7 de maio de 2021): 161–70. http://dx.doi.org/10.4314/bcse.v35i1.14.
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Nanoparticle fabrication using plant extracts is an important alternative method because it is non-toxic, biocompatible, and environmentally friendly. In this study, green synthesis of MgO nanoparticles using Moringa oleifera leaf water extracts was conducted by mixing the extract and a solution of magnesium chloride. The product was characterized using different techniques, i.e. UV-Visible (UV-Vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The UV-Vis spectrum of MgO nanoparticles shows an absorption at 280 nm. The size of the synthesized MgO nanoparticles ranges from 20-50 nm. The antibacterial activity of MgO nanoparticles was seen from the zone of inhibition against Staphylococcus aureus (6.3 mm) and against Escherichia coli (6 mm). MgO nanoparticles have been successfully fabricated using Moringa oleifera leaf aqueous extracts, providing an alternative method for synthesizing MgO nanoparticles.
KEY WORDS: Antibacterial activity, Escherchia coli, MgO nanoparticles, Moringa oleifera, Staphylococcus aureus
Bull. Chem. Soc. Ethiop. 2021, 35(1), 161-170.
DOI: https://dx.doi.org/10.4314/bcse.v35i1.14
Teses / dissertações sobre o assunto "MgO nanoparticule"
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Gonzalez, Joa Javier Antonio. "Mesoscale dislocation simulation accounting for surfaces using the superposition method : Application to nanomechanics". Electronic Thesis or Diss., Lyon, INSA, 2022. http://www.theses.fr/2022ISAL0129.
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Les nano-objets (fils, particules, films minces) sont connus pour leurs propriétés mécaniques exceptionnelles au regard de leurs homologues massifs. Diverses techniques expérimentales (microscopie électronique à transmission ou à balayage, diffraction des rayons X) sont utilisées pour étudier les nano-objets, complétées par des approches numériques telle que la dynamique moléculaire. Bien que fournissant des détails à l'échelle atomique, la dynamique moléculaire reste limitée en termes de taille et de vitesse de déformation, ouvrant la porte à d'autres méthodes comme la dynamique des dislocations discrète. La dynamique des dislocations discrète permet de décrire l'évolution d'une population de dislocations à l’échelle du grain mais est généralement utilisée dans des ensembles quasi-infinis en utilisant des cellules de simulation particulièrement grandes ou des conditions limites périodiques. Par conséquent, la dynamique des dislocations discrète seule ne peut fournir une description physique des surfaces d’un échantillon, surfaces à l'origine de nombreux processus à l'échelle nanométrique. Cette étude vise à modéliser mieux et plus fidèlement la mécanique des nano-objets en tenant compte des interactions complexes entre les dislocations et les surfaces. Pour ce faire, un nouvel outil appelé El-Numodis a été développé. El-Numodis repose sur le couplage du code de dynamique des dislocations discrète Numodis avec le code d'éléments finis Elmer en utilisant la méthode de superposition. Nous présentons ici les étapes de développement d'El-Numodis (pilotes de couplage, forces d'image des dislocations, algorithme de nucléation, etc.) ainsi que plusieurs applications incluant des problèmes d'élasticité classiques dans lesquels des surfaces sont impliquées. A titre d'exemple, la modélisation de films minces métalliques fcc montre l'influence majeure des surfaces sur la mécanique des nano-objets. Enfin, El-Numodis est utilisé pour modéliser la mécanique de nanoparticules céramiques où la nucléation de dislocation informée de manière atomistique, combinée à la théorie de l'état de transition, permet d'étudier le rôle de la taille, température et de la vitesse de déformation sur la déformation de nanocubes de MgONano-objects (wires, particles, thin films) are known for their outstanding mechanical properties when compared to their bulk counterparts. Various experimental techniques (transmission and scanning electron microscopy, X-ray diffraction) are used to investigate nano-objects, all complemented by computational approaches such as molecular dynamics. While modelling atomic-scale processes in the details, molecular dynamics is limited in terms of sample size and strain rates opening doors to other methods such as the discrete dislocation dynamics. Discrete dislocation dynamics is able to describe the evolution of a dislocation population at the mesoscale but is mostly used to describe quasi-infinite ensembles using either particularly large simulation cells or relying on periodic boundary conditions. Consequently, standalone discrete dislocation dynamics cannot provide a complete description of sample surfaces that are known to be at the roots of several nanoscale processes. This study aims at better and faithfully model the mechanics of nano-objects accounting for the complex interactions between dislocations and surfaces. For this purpose, a new tool called El-Numodis was developed. El-Numodis relies on the coupling of the discrete dislocation dynamics code Numodis with the finite elements code Elmer using the superposition method in which the stress field generated by a dislocation population is corrected at the virtual surfaces of a finite-size sample using a finite-element elastic solver. In this work, we present the main development stages of El-Numodis (coupling drivers, dislocation image forces, nucleation algorithm, etc.) as well as several applications including analytically soluble elasticity problems in which surfaces are involved. As an example, the modelling of face-centered cubic metal thin films practically demonstrates the influence of surfaces on nano-objects mechanics. Finally, El-Numodis is used to model the mechanics of ceramics nanoparticles for which atomistically-informed dislocation nucleation as combined to the transition state theory allow to investigate the role of size, temperature and strain rate on the mechanical properties of MgO nanoparticles
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CALEFFI, MATTEO. "Deposizione di nanoparticelle core-shell di Ag@MgO e Au@MgO su TiO2 meso-poroso mediante sorgente di aggregazione di nanoparticelle: una strategia per migliorare l'efficienza di Celle Solari di Perovskite". Doctoral thesis, Università degli studi di Modena e Reggio Emilia, 2022. http://hdl.handle.net/11380/1271921.
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Attualmente, l'accoppiamento fra nanoparticelle metalliche (NP) e materiali foto-attivi rappresenta una via promettente per migliorare le efficienze di dispositivi in applicazioni di fotocatalisi ed energia solare. Nella maggior parte dei casi, il miglioramento dell'efficienza dei dispositivi solari mediante funzionalizzazione con NP core-shell è stato ottenuto attraverso metodi chimici sia per la sintesi che per la deposizione delle NP. Questi metodi sono limitati nella combinazione di materiali di core e shell, così come alcuni inconvenienti legati all'uso di solventi. D'altra parte, le sorgenti di aggregazione di NP basate su magnetron-sputtering, rappresentano un approccio versatile per depositare NP su superfici, con controllo preciso sulle quantità e sulle dimensioni medie, consentendo di ottenere strutture core-shell e/o NP metalliche incorporate in una matrice ultrasottile. Durante il mio progetto di dottorato, esploro le potenzialità nell'applicazione di questa tecnica alle celle solari di perovskite (PSC), con l'obiettivo di studiare le proprietà dei substrati funzionalizzati e di migliorarne l’assorbimento della luce e l'efficienza (PCE). In particolare, le NP core-shell Ag@MgO e Au@MgO vengono depositate sullo strato mesoporoso di TiO2, in PSC a triplo catione. Sono stati considerati ricoprimenti diversi di NP che variano tra l'1 e il 25% e le proprietà strutturali e morfologiche dei substrati funzionalizzati sono state caratterizzate combinando informazioni ottenute da HRTEM, EDX, SEM, AFM e XPS. La struttura delle NP di Ag@MgO è studiata mediante HRTEM ed EDXS, mostrando che il core di Ag presenta una struttura icosaedrica multi-dominio e dimostrando che la crescita di MgO è localizzata attorno ai nuclei di Ag, confermando l’ottenimento di una struttura core-shell. Le proprietà morfologiche delle NP, ad es. le dimensioni laterali e l'altezza, sono determinate rispettivamente tramite SEM e AFM. L'altezza media delle NP H è stimata intorno a 4 nm per le NP di Ag@MgO, e intorno a 6 nm per quelle di Au@MgO, mentre per entrambi i sistemi la dimensione laterale media D è di circa 8 nm. Quest'ultima aumenta in funzione del ricoprimento, cosicché le NP sono caratterizzate da un rapporto D/H variabile tra 1 e 2. Sia per le NP di Ag che per quelle di Au, gli esperimenti di stabilità termica fino a 150°C sono stati monitorati mediante XPS e dimostrano il ruolo benefico svolto da MgO nel preservare la stabilità termica delle NP ed evitarne l'ossidazione. Le trasmissività UV-Vis (T) e le riflettività (R) dei substrati e di quelli arricchiti con NP sono misurate con uno spettrofotometro, determinandone la Optical Loss differenziale (ΔL) per diversi ricoprimenti di NP. Gli spettri ottici dei campioni contenenti Ag@MgO rivelano un picco a 430 nm. Le simulazioni di polarizzabilità delle NP basate su Maxwell-Garnett confermano che il picco è correlato all'assorbimento del LSPR di Ag, mentre la sua posizione dipende dal rapporto D/H. Gli spettri ottici di campioni contenenti Au@MgO rivelano un picco più largo, a 520 nm, mostrando - in accordo con la letteratura e con i risultati delle simulazioni - che la banda di LSPR è più grande che nel caso di NP di Ag. Come ultima fase, viene esaminato l’effetto delle NP di Ag@MgO e Au@MgO nelle PSC. Vengono testati dispositivi con diverso ricoprimento superficiale tra 0 e 25% e per diversi spessori nominali della shell tra 2,5 e 0,6 nm. Per le PSC arricchite con NP di Ag@MgO, il ricoprimento ottimale è di 1,5%, che porta ad un aumento dell’efficienza dei dispositivi del 5%, fino al 17,8%, correlato con l’aumento di JSC e di VOC. D'altro canto, le misure preliminari relative all'incorporazione di NP Au@MgO nelle PSC non hanno determinato un aumento dell'efficienza e meritano ulteriori indagini.Nowadays, coupling of Metal nanoparticles (NPs) with photo-active materials represents a promising route to enhance device performances in photocatalysis and solar energy applications. In most cases, efficiency improvement in photovoltaic devices by core-shell NP functionalization was obtained via chemical wet methods for both core and shell synthesis and deposition. These methods – though readily suitable for scalability – presents some limitations in combining NP and shell materials, as well as some drawbacks related to the use of solvents. On the other hand, nanocluster aggregation sources based on magnetron-sputtering represent a versatile route to deposit NPs on any selected surface, with precise control of both their quantity and average dimension. Moreover, co-deposition techniques allow to obtain core-shell structures and/or metal NPs embedded in ultra-thin host matrix. During my PhD project, I explore the potentialities of applying this methodology to Perovskite Solar Cells (PSCs), aiming to investigate the properties of these functionalized substrates and, ultimately, to improve their light harvesting and power conversion efficiency (PCE). In particular, Ag@MgO and Au@MgO core-shell NPs are deposited on the mesoporous TiO2 surface Electron-Transport Layer of triple-cation PSCs. Different NP coverage varying between 1-25% has been considered, and the structural and morphological properties of the functionalized substrate has been fully characterized by combining complementary information obtained by HRTEM, EDX, SEM, AFM and XPS. The Ag@MgO NP core-shell structure is investigated with HRTEM and EDXS, showing that the Ag core presents a multi-twinned icosahedral structure and proving that the MgO growth is preferentially localized around the metal cores, i.e. that a core-shell structure is obtained. Furthermore, NP morphological properties, i.e. their lateral size and height, are determined via SEM and AFM, respectively. The average NP height H is estimated around 4 nm and 6nm for Ag@MgO NPs and Au@MgO NPs, respectively, while for both systems the average lateral size D is found around 8 nm. The latter slightly increases as a function of coverage, so that the NP spheroidal shape is characterized by an aspect ratio D/H varying between 1 and 2. For both Ag and Au NPs, XPS annealing experiments performed in UHV up to 150°C demonstrate the beneficial role played by the MgO shell in preserving their thermal stability and avoiding oxidation. The UV-Vis Transmittivity (T) and Reflectivity (R) of pristine and NP-enriched substrates are measured with a spectrophotometer, thus determining the Differential Optical Loss (ΔL) spectra for different NP coverages. For Ag@MgO NP-enriched samples, spectra reveal an intense and broad band, peaked at 430 nm. NP polarizability simulations based on Maxwell-Garnett approach confirm that the band maximum is related to Ag LSPR absorption, while its position depends on the NP aspect ratio. Au@MgO NP spectra reveal a broader optical loss band, peaked at 520 nm, showing - in agreement with literature and with the results of simulations - that the plasmonic loss band is larger than the case with Ag NPs. As last step, the incorporation of core–shell Ag@MgO and Au@MgO NPs into PSCs is investigated. Devices with different NP surface coverage between 0 and 25% and for different nominal shell thickness between 2.5 and 0.6 nm are tested. For Ag@MgO NP-enriched PSCs, the optimum coverage is 1.5%, which leads to a relative increase of 5% in terms of device efficiencies up to 17.8%, related to an increase in both JSC and VOC. On the other hand, preliminary measures of the incorporation of Au@MgO core-shell NPs in PSCs did not result in an efficiency increase and deserve further investigation.
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Bo, Huang. "The Developments of Novel Nanomaterials with Non-Noble Metal Elements RuxCu1-x Solid-Solution Nanoparticles and MgO Nanoparticles/Metal-Organic Frameworks―". Kyoto University, 2017. http://hdl.handle.net/2433/226757.
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Xu, Lijun. "Theoretical studies of Pd on MgO(100) surface with density functional and transition state theories /". Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8550.
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Tait, Steven L. "Desorption kinetics of small n-alkanes from MgO(100), Pt(111), and C(0001)/Pt(111) and studies of Pd nanoparticles : growth and sintering on Al₂O₃(0001) and methane dissociation on MgO(100) /". Thesis, Connect to this title online; UW restricted, 2005. http://hdl.handle.net/1773/9630.
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Poucin, Cyprien. "Borane adsorption on MgO nanoparticles for increased catalytic activity in the cycloaddition of CO2 on epoxides". Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS142.pdf.
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La capture et la valorisation du dioxyde de carbone sont devenus des défis majeurs pour les décennies à venir. Les technologies de capture sont déjà suffisamment matures pour être mises en œuvre à l'échelle industrielle, mais les technologies de valorisation font encore défaut. Ce travail de thèse se concentre sur le développement de nouveaux catalyseurs pour la valorisation chimique du CO2. L'introduction bibliographique souligne le potentiel des oxydes alcalino-terreux pour la capture et la valorisation du CO2 en raison de leur capacité à former facilement des carbonates, ainsi que le développement récent de la chimie des Paires de Lewis Frustrées (FLP) pour l'activation de petites molécules comme le CO2. Nous y proposons une stratégie de synthèse de nanoparticules d'oxyde de magnésium fonctionnalisées avec des ligands boranes pour créer une interaction de type FLP à la surface et augmenter l'activité catalytique des nanoparticules dans la cycloaddition du CO2 sur des époxydes. Dans la première partie de ce travail, la synthèse de nanoparticules d'oxyde de magnésium par précipitation-calcination est étudiée. Les paramètres de réaction tels que la température de calcination et les lavages post-synthèse ont un impact sur la morphologie et l'état de surface des nanoparticules. La deuxième partie de ce travail se concentre sur l'adsorption de boranes sur les nanoparticules de MgO avec et sans présence de CO2. La preuve d'une interaction MgO-CO2-BPh3 est apportée par des analyses de spectroscopie infrarouge. Une interaction unique entre MgO et le chloroborane BCl2Ph est mise en évidence par un changement de couleur visuel des nanoparticules ainsi que par spectroscopie infrarouge. La dernière partie de ce travail se concentre sur l'étude catalytique de la réaction de cycloaddition. La comparaison entre les différents catalyseurs MgO confirme l'importance des paramètres de synthèse des nanoparticules sur leur activité. L'adsorption de boranes modifie l'activité et/ou la sélectivité de MgO en fonction du solvant de réaction. L'ajout de BCl2Ph augmente l'activité du catalyseur MgO d'un facteur 10 mais réduit également sa sélectivité vers la formation du carbonate cyclique. L'impact de la température, de la concentration et de la durée de la réaction sur les performances catalytiques de ce couple nanoparticule-ligand est étudié afin de dévoiler l'origine de cette synergie inédite entre MgO et BCl2PhCarbon dioxide capture and valorisation have become major challenges for the future decades. Capture technologies are already mature enough to start being implemented at industrial scale but valorisation technologies are still lacking. This thesis work focuses on the development of new catalysts for CO2 chemical valorisation. The bibliographic introduction emphasizes the potential alkaline earth oxides for CO2 capture and valorisation due to their ability to easily form carbonates, as well as the recent development of Frustrated Lewis Pair (FLP) chemistry for the activation of small molecules like CO2. We propose a strategy to synthesize magnesium oxide nanoparticles functionalised with borane ligands to create FLP-like interaction at the surface and increase the catalytic activity of the nanoparticles in the cycloaddition of CO2 on epoxides. In the first part of this work, the synthesis of magnesium oxide nanoparticles by precipitation-calcination is studied. Reaction parameters like calcination temperature and post synthesis washings are shown to impact the nanoparticles morphology and surface state. The second part of this work focuses on borane adsorption on MgO nanoparticles with and without presence of CO2. Proof of a MgO-CO2-BPh3 interaction is found using infrared spectroscopy analyses. A unique interaction between MgO and the chloroborane BCl2Ph is evidenced by a visual colour change of the nanoparticles and by infrared spectroscopy. The last part of this work focuses on the catalytic study of the cycloaddition reaction. Comparison between the different MgO catalysts confirmes the importance of the nanoparticles synthesis parameters on their activity. Adsorption of borane modifies the MgO activity and/or selectivity depending on the reaction solvent. The addition of BCl2Ph increases the activity of the MgO catalyst by a factor 10 but also reduces the selectivity toward cyclic carbonate. Impact of temperature, concentration and reaction duration on the catalytic performances of this nanoparticle¬ ligand pair is studied to unveil the origin of this unreported synergy between MgO and BCl2Ph
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Haque, Francia. "Réactivité de nanoparticules d'oxydes d'orientations définies". Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066420/document.
Texto completo da fonteResumo:
La connaissance d’un système gaz/solide requiert l’analyse de l’adsorption, du premier stade jusqu’à saturation. C’est la motivation de l’analyse des surfaces sous vide. L’approche des surfaces divisées est souvent tronquée. Pratiquée à des pressions suffisamment élevées pour être compatible avec un temps de réaction raisonnable, elle ne permet pas l'analyse de la surface nue à la monocouche. L’objectif du présent travail a été d’établir une continuité d’observation par FTIR, de l’UHV à la pression ambiante, de poudres de MgO, ZnO et ZnxMg1-xO exposées à l’eau ou à l’hydrogène. Il a été montré que les fumées de ZnO se comparent à des cristaux présentant les faces (0001), (0001̅), (101̅0), (112̅0), avec un rapport non-polaire/polaire de 75/25. Par FTIR combinée à la photoémission et à la désorption thermique, trois étapes de l’hydroxylation des fumées de MgO ont été identifiées : défauts ponctuels (10-8 mbar), marches (10-6 mbar) puis terrasses (> 10-5 mbar), avec une restructuration qui prouve que l’eau change la structure de surface de MgO. La représentation commune de la surface de MgO par une suite de facettes (100) est mise en cause. Aux faibles teneurs en zinc, l’oxyde mixte ZnxMg1-xO est formé de cristallites cubiques de même structure que MgO. Le zinc en substitution tend à ségréger vers les sites de basse coordinence où il affecte les propriétés d’adsorption d’eau et d’hydrogène. Par ailleurs, le mélange ZnO-MgO obtenu par combustion d’alliage ZnMg offre une possibilité d’application grâce aux propriétés bactéricides de ZnO et de faible toxicité de MgO. L’ensemble des résultats montre la pertinence de l’étude des poudres pratiquée dans les conditions de l’UHVThe analysis of adsorption from the first stage to saturation is necessary to understand gas/solid interactions. This is the motivation for surface analysis under vacuum. The common approach of dispersed materials surfaces is incomplete since working pressures, that are high enough to achieve reasonable reaction times, do not allow studies of powder surfaces from bare to fully covered. The aim of the present work is to examine the successive changes of ZnO, MgO and ZnxMg1-xO nanopowders upon exposure to water or hydrogen from UHV to the ambient by FTIR. It is shown that ZnO smokes behave in a same way as a collection of single crystals which exhibit (0001), (0001̅), (101̅0) and (112̅0) faces with a non-polar/polar ratio of 75/25. Combining FTIR with XPS and TPD techniques, three stages of hydroxylation were identified on MgO smokes: point defects (10-8 mbar), steps (10-6 mbar) then terraces (> 10-5 mbar). Results indicate a reorganisation of surface structure showing that water adsorption on MgO(100) is an irreversible process. The common model of MgO as a series of (100) facets is questioned. At low concentrations of zinc, the mixed oxide ZnxMg1-xO consists of crystals with similar structure as MgO. A segregation of Zn2+ toward low coordinated surface sites is suggested to explain the changes in reactivity of the ZnxMg1-xO with respect to water and hydrogen at low coverages. Furthermore, the mixture ZnO-MgO produced by combustion of ZnMg alloy combines the antibacterial properties of ZnO and the biocompatibility of MgO, interesting for potential applications. The overall results demonstrate the relevance of the study of powders in ultra-high vacuum conditions
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SUSANNA, ANTONIO. "Highly Efficient MeO Nanoparticles as Curing Activator for Rubber Composites". Doctoral thesis, Università degli Studi di Milano-Bicocca, 2016. http://hdl.handle.net/10281/129620.
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The vulcanization of rubber by sulfur is a large-scale industrial process that improves the mechanical properties of unsaturated rubber by the cross-linking of polymer chains. Microcrystalline ZnO particles are currently used as activator to enhance the efficiency of the crosslinking. Due to their not easy dispersion in the rubber matrix and to the relatively small fraction of ZnO which actually reacts with the other curative compounds, a large amount of oxide is required for the process. This leads to a not homogeneous vulcanization with inefficient polymer network structure and a possible release of the metal in the environment with potentially negative effects. Thus, a possible improvement of ZnO efficiency as activator requires an enhancement of its availability, distribution and capability to release Zn2+ ions in the rubber matrix. Aim of this thesis, is the enhancement of the curing efficiency by employing ZnO nanoparticles (NPs) grown on silica filler particles. A simple low-temperature sol-gel procedure was exploited to grow amorphous spherical ZnO NPs directly on silica surface and linked by Si-O-Zn covalent bonds (ZnO/SiO2) which simultaneously behave as curing agent and reinforcing filler. The morphology and crystal structure of ZnO/SiO2 NPs were investigated by XRD and TEM. The nanometric size was assessed by UV reflectance measure, while the Si-O-Zn bond interaction was studied by NMR, ATR-FTIR and XPS and discussed in relation to the NPs dimensions. The ZnO/SiO2 NPs were used to prepare cured polyisoprene nanocomposites loaded with silica. Moreover, the curing efficiency and dynamic mechanical properties of vulcanized ZnO/SiO2 nanocomposites were compared to those obtained by using microcrystalline ZnO as activator in conventional curing processes. In the case of nanocomposite cured with ZnO/SiO2 NPs showed better curing efficiency, higher cross-linking density and improved mechanical properties than the same composites treated by conventional ZnO particles. In order to explain the better efficiency of ZnO/SiO2 NPs in the vulcanization, the pseudo activation energies of the different stages of the process were evaluated by performing DSC measurements on the nanocomposites. The presence of ZnO/SiO2 NPs induces lower activation energies and, therefore, faster kinetics compared to microcrystalline ZnO, particularly in the first steps of the reactions. This is in agreement with the highest ability of zinc in ZnO/SiO2 to react with curatives, thus improving the cross-linking density. The role of ZnO/SiO2 NPs in the crosslinking reaction was further studied by a model compound vulcanization (MCV) approach, using tetramethylethylene as model monomer and analyzing the cured products by LC-MS chromatography and 1H-NMR spectroscopy. The results evidence a higher crosslinking for ZnO/SiO2 due to the larger amount of more stable mono- and di-sulphide crosslinking chains than for conventional ZnO. The comparison between the two catalysts have been also discussed on the basis of FTIR investigation which evidence in ZnO/SiO2 the formation of highly reactive stearate bridged bidentate zinc complex as possible intermediate in accelerating the cross-linking reaction. These results suggest that the proposed material could be considered as promising system for curing industrial application with reduce zinc loading. Finally, similar activator/filler NPs loaded with CaO and MgO were also prepared and tested to replace the Zn in curing process. Nanosized dimension and high dispersion of the oxides improve the efficiency of this activators with respect to system with unsupported crystalline oxides even if their catalityc activity is confirmed to be much lower than ZnO.
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Haque, Francia. "Réactivité de nanoparticules d'oxydes d'orientations définies". Electronic Thesis or Diss., Paris 6, 2015. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2015PA066420.pdf.
Texto completo da fonteResumo:
La connaissance d’un système gaz/solide requiert l’analyse de l’adsorption, du premier stade jusqu’à saturation. C’est la motivation de l’analyse des surfaces sous vide. L’approche des surfaces divisées est souvent tronquée. Pratiquée à des pressions suffisamment élevées pour être compatible avec un temps de réaction raisonnable, elle ne permet pas l'analyse de la surface nue à la monocouche. L’objectif du présent travail a été d’établir une continuité d’observation par FTIR, de l’UHV à la pression ambiante, de poudres de MgO, ZnO et ZnxMg1-xO exposées à l’eau ou à l’hydrogène. Il a été montré que les fumées de ZnO se comparent à des cristaux présentant les faces (0001), (0001̅), (101̅0), (112̅0), avec un rapport non-polaire/polaire de 75/25. Par FTIR combinée à la photoémission et à la désorption thermique, trois étapes de l’hydroxylation des fumées de MgO ont été identifiées : défauts ponctuels (10-8 mbar), marches (10-6 mbar) puis terrasses (> 10-5 mbar), avec une restructuration qui prouve que l’eau change la structure de surface de MgO. La représentation commune de la surface de MgO par une suite de facettes (100) est mise en cause. Aux faibles teneurs en zinc, l’oxyde mixte ZnxMg1-xO est formé de cristallites cubiques de même structure que MgO. Le zinc en substitution tend à ségréger vers les sites de basse coordinence où il affecte les propriétés d’adsorption d’eau et d’hydrogène. Par ailleurs, le mélange ZnO-MgO obtenu par combustion d’alliage ZnMg offre une possibilité d’application grâce aux propriétés bactéricides de ZnO et de faible toxicité de MgO. L’ensemble des résultats montre la pertinence de l’étude des poudres pratiquée dans les conditions de l’UHVThe analysis of adsorption from the first stage to saturation is necessary to understand gas/solid interactions. This is the motivation for surface analysis under vacuum. The common approach of dispersed materials surfaces is incomplete since working pressures, that are high enough to achieve reasonable reaction times, do not allow studies of powder surfaces from bare to fully covered. The aim of the present work is to examine the successive changes of ZnO, MgO and ZnxMg1-xO nanopowders upon exposure to water or hydrogen from UHV to the ambient by FTIR. It is shown that ZnO smokes behave in a same way as a collection of single crystals which exhibit (0001), (0001̅), (101̅0) and (112̅0) faces with a non-polar/polar ratio of 75/25. Combining FTIR with XPS and TPD techniques, three stages of hydroxylation were identified on MgO smokes: point defects (10-8 mbar), steps (10-6 mbar) then terraces (> 10-5 mbar). Results indicate a reorganisation of surface structure showing that water adsorption on MgO(100) is an irreversible process. The common model of MgO as a series of (100) facets is questioned. At low concentrations of zinc, the mixed oxide ZnxMg1-xO consists of crystals with similar structure as MgO. A segregation of Zn2+ toward low coordinated surface sites is suggested to explain the changes in reactivity of the ZnxMg1-xO with respect to water and hydrogen at low coverages. Furthermore, the mixture ZnO-MgO produced by combustion of ZnMg alloy combines the antibacterial properties of ZnO and the biocompatibility of MgO, interesting for potential applications. The overall results demonstrate the relevance of the study of powders in ultra-high vacuum conditions
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Beranger, Murielle. "Etude des modifications de matériaux sous impact d'ions et d'agrégats de haute énergie par excitations électroniques géantes : cas de MgO contenant des nanoprécipités de métal alcalin". Lyon 1, 1996. http://www.theses.fr/1996LYO10168.
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L'objectif de ce travail de doctorat est d'etudier les deplacements atomiques induits par l'interaction electronique entre un ion ou un agregat de haute energie et une cible solide. Le materiau irradie est un monocristal d'oxyde de magnesium contenant des nanoprecipites de metal alcalin (li, na ou rb). Les projectiles utilises sont des ions lourds (kr, sn, pb, u) tres energetiques ( gev) delivres par le grand accelerateur national d'ions lourds de caen, ou des agregats de c#6#0 d'energie 20 mev fournis par l'accelerateur tandem de l'institut de physique nucleaire d'orsay. Ces projectiles deposent la majeure partie de leur energie dans le solide par excitations electroniques et ionisations, et leur perte d'energie electronique est comprise entre 10 et 60 kev/nm dans mgo. L'interaction electronique entre les projectiles et le solide conduit a la formation de defauts ponctuels et etendus dans l'oxyde de magnesium, comme l'ont montre les analyses d'absorption optique, de r. B. S. En geometrie de canalisation et de microscopie electronique en transmission. La section efficace de creation de defauts dans mgo varie comme une fonction puissance avec la perte d'energie electronique des ions incidents et ne depend que peu de la temperature d'irradiation entre 17 et 300 k. Les effets d'ionisation induits par les projectiles dans les echantillons mgo-nanoparticules de metal alcalin provoquent la disparition des particules metalliques. La section efficace de destruction des precipites augmente aussi comme une fonction puissance des pertes d'energie electronique des projectiles dans le solide. La taille des precipites et la vitesse des projectiles sont des parametres importants dans ce processus de modification des inclusions de metal alcalin. Par contre, la temperature d'irradiation entre 17 et 300 k semble avoir peu d'influence sur la destruction des particules metalliques
Capítulos de livros sobre o assunto "MgO nanoparticule"
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Han, D. Y., H. Y. Yang e C. B. Shen. "Preparation of Size Controllable MgO Nanoparticles via Reverse Microemulsion Method". In Materials Science Forum, 3543–46. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-960-1.3543.
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Jin-Phillipp, N. Y., P. Nolte, A. Stierle, P. A. van Aken e H. Dosch. "Direct observation of surface oxidation of Rh nanoparticles on (001) MgO". In EMC 2008 14th European Microscopy Congress 1–5 September 2008, Aachen, Germany, 225–26. Berlin, Heidelberg: Springer Berlin Heidelberg, 2008. http://dx.doi.org/10.1007/978-3-540-85226-1_113.
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Pattanashetty, Shivarudrappa Honnali, Basappa Chidananda Vasantha Kumar, Nisha S. Pattanashetty e Bullapura Matt Santhosh. "Synthesis and Characterization of MgO-Graphene Oxide Nanoparticles for Optoelectronic Devices". In Multifunctional Inorganic Nanomaterials for Energy Applications, 413–20. Boca Raton: CRC Press, 2024. http://dx.doi.org/10.1201/9781003479239-28.
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Sowri Babu, K., A. Ramachandra Reddy e K. Venugopal Reddy. "RETRACTED CHAPTER: An Intense Green Emission From ZnO Nanoparticles Coated with MgO". In Physics of Semiconductor Devices, 869–71. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-03002-9_223.
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Sowri Babu, K., A. Ramachandra Reddy e K. Venugopal Reddy. "Erratum to: An Intense Green Emission From ZnO Nanoparticles Coated with MgO". In Physics of Semiconductor Devices, E1. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-03002-9_241.
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Sukumar, Siladitya, e Satya Prakash Kar. "Enhancement of Cooling Rate Using Biodegradable MgO Nanoparticles During a Cryopreservation Process". In Advances in Air Conditioning and Refrigeration, 23–32. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-6360-7_3.
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Tamil Elakkiya, V., K. Rajaram, R. V. Meenakshi, K. Ravi Shankar e P. Sureshkumar. "Green Synthesis of MgO Nanoparticles Using Sesbania bispinosa and Its In Vitro Effect on Chlorophyll Content in Long Bean Plant". In Green Synthesis of Nanoparticles: Applications and Prospects, 289–300. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-5179-6_13.
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Ngulube, Khumbolake Faith, Amal Abdelhaleem, Manabu Fujii e Mahmoud Nasr. "Photocatalytic Activity of Metal-Doped MgO Nanoparticles for Dye Removal with Cost Estimation". In The 6th International Symposium on Water Resource and Environmental Management, 111–20. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-55989-1_10.
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Boro, Bitopan, Anup Kr Nath, Manash Barthakur e Pankaj Kalita. "Synthesis and Characterization of MgO Nanoparticle and Its In Vitro Cytotoxic Effect on Erythrocytes". In Lecture Notes in Bioengineering, 199–207. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-7409-2_20.
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Sisubalan, Natarajan, Shalini Ramadoss, Muniraj Gnanaraj, Arumugam Vijayan, Karthikeyan Chandrasekaran, Sivamaruthi Bhagavathi Sundaram, Chaiyasut Chaiyavat e Varaprasad Kokkarachedu. "Eco-Friendly Synthesis of MgO Nanoparticles for Biomedical Applications: Advances, Challenges, and Future Prospects". In Nanotechnology in the Life Sciences, 201–26. Cham: Springer International Publishing, 2024. http://dx.doi.org/10.1007/978-3-031-50093-0_9.
Texto completo da fonteTrabalhos de conferências sobre o assunto "MgO nanoparticule"
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Hussein ABDULSATTAR, Marwah, e Sara Abdulbasit TURKI. "EVALUATION THE SURFACE ROUGHNESS OF POLYMETHYLMETHACRYLATE AFTER REINFORCEMENT WITH MAGNESIUM OXIDE". In VIII.International ScientificCongressofPure,AppliedandTechnological Sciences. Rimar Academy, 2023. http://dx.doi.org/10.47832/minarcongress8-22.
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Denture fractures are frequent clinical event in prosthodontics services which remain as unsolved problems. The aim of this study was to evaluate the effect of incorporation Magnesium oxides nanoparticles with different concentrations on surface roughness of heat cure acrylic resin. A total of 40-disc shape specimens with a diameter of (12±0.1) mm and a thickness of (2±0.1) mm were prepared from heat cure acrylic resin. They were grouped into 4 groups according to nanoparticles concentrations (10) specimens for each group, then they are subjected to roughness test. Control group (A): (10 specimens) without addition. Group (B): 10 specimens of acrylic resin with (1%) concentration of Magnesium oxide. Group (C): 10 specimens of acrylic resin with (3%) concentration of Magnesium oxide. Group (D): 10 specimens of acrylic resin with (5%) concentration of Magnesium oxide. Results: The results showed the highest mean value was for Control group which untreated with nanoparticles (1.4520) and the lowest mean value was for group containing 3% of Mgo nanoparticle (0.0465). Conclusion: Adding limited concentration of MgO (3%) have a positive effect on surface roughness of heat-cured acrylic resins. any Increase in Concentration of MgO (5%) will effect adversely on roughness of acrylic resin
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Yu, Wei, Hua-Qing Xie, Yang Li e Li-Fei Chen. "The Thermal Transport Properties of Ethylene Glycol Based MGO Nanofluids". In ASME 2009 7th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2009. http://dx.doi.org/10.1115/icnmm2009-82032.
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Ethylene glycol based nanofluids containing MgO nanoparticles (MgO-EG) were prepared, and the transport properties including thermal conductivity and viscosity were measured. The results show that the thermal conductivity of MgO-EG nanofluid depends strongly on particle concentration, and it increases nonlinearly with the volume fraction of nanoparticles. The thermal conductivity of MgO-EG nanofluids is larger than that of nanofluids containing the same volume fraction of TiO2, ZnO, Al2O3 and SiO2, maybe due to its lowest viscosity among the tested metallic oxide nanofluids. Thermal conductivity enhancement of MgO-EG nanofluids appears weak dependence on temperature from 10 to 60°C, and the enhanced ratios are almost constant. Viscosity measurements show that MgO-EG nanofluids demonstrate Newtonian behavior, and the viscosity significantly decreases with temperature. The thermal conductivity and viscosity increments of nanofluids are higher than those of the existing classical models for the solid-liquid mixture.
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Ali, Abdallah Y. M., Mohammed Fuseini, Essam M. Abo-Zahhad, M. F. El-Kady e A. H. El-Shazly. "Pressure Drop Study in Cylindrical Microchannels: Using Graphene Oxide and Magnesia Nanofluids". In ASME 2020 Fluids Engineering Division Summer Meeting collocated with the ASME 2020 Heat Transfer Summer Conference and the ASME 2020 18th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/fedsm2020-20352.
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Abstract The pressure drop and friction factor for the flow in horizontal smooth microtubes were investigated experimentally over a wide variety of Reynolds numbers in the laminar region under hydrodynamically fully developed conditions. The plain pipes are fabricated from 316 stainless steel and provided by (Swagelok Co., USA) with inner diameters of 0.770 mm and 0.510 mm and the length is 500 mm for both microchannels. For this purpose, graphene oxide (GO) nanosheets and magnesium oxide (MgO) nanoparticles were synthesized then characterized using standard methods such as X-ray powder diffractometer (XRD) and Transmission Electron Microscope (TEM). The prepared GO and MgO nanomaterial were added to distilled water to prepare nanofluids with mass fractions of 0.25, 0.5, 0.75, and 1 wt.% as working fluids and passes through one end of the microchannel to the other by a magnetically coupled gear programmable pump with variable speed that drives it. This study predicts the behavior of fluid flow in the microchannel for the range of dimensions used. Comparisons of pressure drop characteristics are given in terms of nanoparticle mass fractions and tube diameters. As a result, MgO nanofluids recorded higher pressure drop with an increase in the concentration of the nanofluids due to its higher viscosity followed by GO nanofluids.
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He, Zhi Zhu, De Rui Di e Jing Liu. "Enhancement of Cryosurgery Using Biodegradable MgO Nanoparticles". In ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/mnhmt2012-75218.
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Presently an unavoidable defect in nano-cryosurgery is involved with the toxicity and biocompatibility of the foreign particles. Attempting to overcome the shortcomings mentioned above, based on our previous work, MgO nanoparticles have been used as a biodegradable and nontoxic agent in enhancing the nano-cryosurgery output. In this paper we present a three dimensional numerical study to investigate the significant thermal effects of MgO nanoparticles on the iceball evolution during cryosurgery of target tissue. Both of theoretical analysis and numerical simulation confirm that the excellent thermo-physical properties of MgO nanoparticles may be a quite important factor during iceball growth. This work may enhance current understanding of the factors for determining the effects of cryosurgery.
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Razali, Norzafirah, Ivy Ching Hsia Chai, Arif Azhan A Manap e M. Iqbal Mahamad Amir. "Enhanced Foam Stability Using Nanoparticle in High Salinity High Temperature Condition for Eor Application". In Abu Dhabi International Petroleum Exhibition & Conference. SPE, 2021. http://dx.doi.org/10.2118/208196-ms.
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Abstract The capability of commercial nanoparticles to perform as foam stabilizer were investigated at reservoir temperature of 96°C. Al2O3, Fe3O4, Co3O4, CuO, MgO, NiO, ZrO2, ZnO and SiO2 nanoparticles that were characterized using XRD, FTIR, FESEM-EDX, TEM and PSA, were blended in the in-house formulated surfactant named IVF respectively at a particular ratio. The test was performed with and without the presence of reservoir crude oil. Results showed that formulation with nanoparticles enhanced foam stability by having longer foam half-life than the IVF surfactant alone, especially in the absence of oil. Only SiO2 nanoparticles were observed to have improved the foam stability in both test conditions. The unique properties of SiO2 as a semi-metal oxide material may have contributed to the insensitivity of SiO2 nanoparticle towards crude oil which is known as a foam destabilizer. The physical barrier that was formed by SiO2 nanoparticles at the foam lamella were probably unaffected by the presence of crude oil, thus allowing the foams to maintain its stability. In thermal stability tests, we observed the instability of all nanoparticles in the IVF formulation at 96°C. Nanoparticles were observed to have separated and settled within 24 hours. Therefore, surface modification of nanoparticle was done to establish steric stabilization by grafting macro-molecule of polymer onto the surface of SiO2. This in-house developed polymer grafted silica nanoparticles are named ZPG nanoparticles. The ZPG nanoparticles passed the thermal stability test at 96°C for a duration of 3 months. In the foam wetness analysis, ZPG nanoparticles were observed to have produced more wet foams than IVF formulation alone, indicating that ZPG is suitable to be used as foam stabilizer for EOR process as it showed catalytic behaviour and thermally well-stable at reservoir temperature.
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Kelley, David F., e Haohua Tu. "Intraband Spectroscopy of GaSe Nanoparticles and InSe/GaSe Nanoparticle Heterojunctions". In International Conference on Ultrafast Phenomena. Washington, D.C.: OSA, 2006. http://dx.doi.org/10.1364/up.2006.mg4.
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Stoimenov, Peter, George Marchin e Kenneth Klabunde. "Inactivation of Microcystins by Nanoparticulate MgO Formulations". In NanoTech 2002 - "At the Edge of Revolution". Reston, Virigina: American Institute of Aeronautics and Astronautics, 2002. http://dx.doi.org/10.2514/6.2002-5700.
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Bhoi, Himani, Pragya Joshi, Khushboo Punia, Ganesh Lal e Sudhish Kumar. "Synthesis and rietveld refinement of MgO nanoparticles". In 3RD INTERNATIONAL CONFERENCE ON CONDENSED MATTER AND APPLIED PHYSICS (ICC-2019). AIP Publishing, 2020. http://dx.doi.org/10.1063/5.0001269.
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Samba, Mohammed A., Hafsa A. Hassan, Mahjouba S. Munayr, Moataz Yusef, Abdelkareem Eschweido, Hamed Burkan e Mahmoud O. Elsharafi. "Nanoparticles EOR Aluminum Oxide (Al2O3) Used As a Spontaneous Imbibition Test for Sandstone Core". In ASME 2019 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/imece2019-10283.
Texto completo da fonteResumo:
Abstract There are three types of oil production energy operations, primary recovery, secondary recovery and enhanced oil recovery (EOR). EOR consider as the last period for production operations. Where the EOR classify into many types such as thermal injection, gas injection, microbial EOR and chemical flooding. Chemical flooding classified into many types such as polymer, surfactant, alkaline and nanoparticles (NP). NP can be classified into many types such as Iron Oxide (Fe2O3), Aluminum Oxide (Al2O3) and Magnesium Oxide (MgO) etc. In this study NP Aluminum oxide (Al2O3) were used to enhance the oil recovery. The main objective of this study is to use the Nanoparticles EOR (Al2O3) and know it is effect on increasing the extraction of oil from cores. The big motivation of using Al2O3 that it is easy to extract it from raw clay. However, the raw clay is available in Libya and using it will be more economic than using other method of chemical EOR. Nanoparticles EOR Aluminum oxide (Al2O3) used as a spontaneous imbibition test for sandstone core samples after saturated by crude oil. A spontaneous imbibition test consisting of two scenarios of nanoparticle solution (Al2O3) with change temperature and compared with one scenario of distilled water. The spontaneous imbibition test was performed in this study at room temperature to oven temperature (30C°, 40C°, 50C°, 60C°, 70C°). The results shown that the oil recovery increases with the increase of the concentration of nanoparticle (Al2O3) and increase the temperature. The higher oil recovery was 76.04% at NP (Al2O3) concentration 1%. Finally, oil swelling and adsorption (NP (Al2O3) with oil drops) have been noticed during the extraction of oil. Thus, the gravity force will be higher than the capillary force.
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Goh, C. S., J. Wei e M. Gupta. "A Comparison of the Processing Routes on the Properties of Mg Reinforced With Nanosize MgO". In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10570.
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Powder metallurgy and liquid metallurgy techniques were used to fabricate Mg reinforced with different volume fraction of nano-size MgO particles. A higher volume fraction of MgO particles could be added into the Mg matrix when the liquid metallurgy technique was used. Microstructural analysis was carried out to examine the distribution of the nanoparticles in the Mg matrix when different processing routes were chosen. Individual particles together with sparsely distributed agglomerations could be discerned in the Mg matrix for both processing routes. Mechanical properties results revealed that a more substantial improvement in macrohardness and tensile properties could be achieved by using the liquid metallurgy route where a higher amount of nano-size MgO particles could be incorporated.
Relatórios de organizações sobre o assunto "MgO nanoparticule"
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Chefetz, Benny, Baoshan Xing, Leor Eshed-Williams, Tamara Polubesova e Jason Unrine. DOM affected behavior of manufactured nanoparticles in soil-plant system. United States Department of Agriculture, janeiro de 2016. http://dx.doi.org/10.32747/2016.7604286.bard.
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The overall goal of this project was to elucidate the role of dissolved organic matter (DOM) in soil retention, bioavailability and plant uptake of silver and cerium oxide NPs. The environmental risks of manufactured nanoparticles (NPs) are attracting increasing attention from both industrial and scientific communities. These NPs have shown to be taken-up, translocated and bio- accumulated in plant edible parts. However, very little is known about the behavior of NPs in soil-plant system as affected by dissolved organic matter (DOM). Thus DOM effect on NPs behavior is critical to assessing the environmental fate and risks related to NP exposure. Carbon-based nanomaterials embedded with metal NPs demonstrate a great potential to serve as catalyst and disinfectors. Hence, synthesis of novel carbon-based nanocomposites and testing them in the environmentally relevant conditions (particularly in the DOM presence) is important for their implementation in water purification. Sorption of DOM on Ag-Ag₂S NPs, CeO₂ NPs and synthesized Ag-Fe₃O₄-carbon nanotubebifunctional composite has been studied. High DOM concentration (50mg/L) decreased the adsorptive and catalytic efficiencies of all synthesized NPs. Recyclable Ag-Fe₃O₄-carbon nanotube composite exhibited excellent catalytic and anti-bacterial action, providing complete reduction of common pollutants and inactivating gram-negative and gram-positive bacteria at environmentally relevant DOM concentrations (5-10 mg/L). Our composite material may be suitable for water purification ranging from natural to the industrial waste effluents. We also examined the role of maize (Zeamays L.)-derived root exudates (a form of DOM) and their components on the aggregation and dissolution of CuONPs in the rhizosphere. Root exudates (RE) significantly inhibited the aggregation of CuONPs regardless of ionic strength and electrolyte type. With RE, the critical coagulation concentration of CuONPs in NaCl shifted from 30 to 125 mM and the value in CaCl₂ shifted from 4 to 20 mM. This inhibition was correlated with molecular weight (MW) of RE fractions. Higher MW fraction (> 10 kDa) reduced the aggregation most. RE also significantly promoted the dissolution of CuONPs and lower MW fraction (< 3 kDa) RE mainly contributed to this process. Also, Cu accumulation in plant root tissues was significantly enhanced by RE. This study provides useful insights into the interactions between RE and CuONPs, which is of significance for the safe use of CuONPs-based antimicrobial products in agricultural production. Wheat root exudates (RE) had high reducing ability to convert Ag+ to nAg under light exposure. Photo-induced reduction of Ag+ to nAg in pristine RE was mainly attributed to the 0-3 kDa fraction. Quantification of the silver species change over time suggested that Cl⁻ played an important role in photoconversion of Ag+ to nAg through the formation and redox cycling of photoreactiveAgCl. Potential electron donors for the photoreduction of Ag+ were identified to be reducing sugars and organic acids of low MW. Meanwhile, the stabilization of the formed particles was controlled by both low (0-3 kDa) and high (>3 kDa) MW molecules. This work provides new information for the formation mechanism of metal nanoparticles mediated by RE, which may further our understanding of the biogeochemical cycling and toxicity of heavy metal ions in agricultural and environmental systems. Copper sulfide nanoparticles (CuSNPs) at 1:1 and 1:4 ratios of Cu and S were synthesized, and their respective antifungal efficacy was evaluated against the pathogenic activity of Gibberellafujikuroi(Bakanae disease) in rice (Oryza sativa). In a 2-d in vitro study, CuS decreased G. fujikuroiColony- Forming Units (CFU) compared to controls. In a greenhouse study, treating with CuSNPs at 50 mg/L at the seed stage significantly decreased disease incidence on rice while the commercial Cu-based pesticide Kocide 3000 had no impact on disease. Foliar-applied CuONPs and CuS (1:1) NPs decreased disease incidence by 30.0 and 32.5%, respectively, which outperformed CuS (1:4) NPs (15%) and Kocide 3000 (12.5%). CuS (1:4) NPs also modulated the shoot salicylic acid (SA) and Jasmonic acid (JA) production to enhance the plant defense mechanisms against G. fujikuroiinfection. These results are useful for improving the delivery efficiency of agrichemicals via nano-enabled strategies while minimizing their environmental impact, and advance our understanding of the defense mechanisms triggered by the NPs presence in plants.