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Littérature scientifique sur le sujet « COPPER OXIDE NANOPARTICLE »

Auteur : Grafiati
Publié le 26 octobre 2023

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Articles de revues sur le sujet "COPPER OXIDE NANOPARTICLE"

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Saif Hasan, Syed, Sanjay Singh, Rasesh Y. Parikh, Mahesh S. Dharne, Milind S. Patole, B. L. V. Prasad et Yogesh S. Shouche. « Bacterial Synthesis of Copper/Copper Oxide Nanoparticles ». Journal of Nanoscience and Nanotechnology 8, no 6 (1 juin 2008) : 3191–96. http://dx.doi.org/10.1166/jnn.2008.095.

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A bacterial mediated synthesis of copper/copper oxide nanoparticle composite is reported. A Gram-negative bacterium belonging to the genus Serratia was isolated from the midgut of Stibara sp., an insect of the Cerambycidae family of beetles found in the Northwestern Ghats of India. This is a unique bacterium that is quite specific for the synthesis of copper oxide nanoparticles as several other strains isolated from the same insect and common Indian mosquitoes did not result in nanoparticle formation. By following the reaction systematically, we could delineate that the nanoparticle formation occurs intracellularly. However, the process results in the killing of bacterial cells. Subsequently the nanoparticles leak out as the cell wall disintegrates. The nanoparticles formed are thoroughly characterized by UV-Vis, TEM, XRD, XPS and FTIR studies.
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Liang, Septimus H., Shiliang Wang et David B. Pedersen. « Adsorption of HCN onto Copper@Copper-Oxide Core–Shell Nanoparticle Systems ». Adsorption Science & ; Technology 27, no 4 (mai 2009) : 349–61. http://dx.doi.org/10.1260/026361709790252632.

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Copper compounds are widely used as impregnants that enhance the removal of HCN by carbon-based filter media. The reaction mechanism involved is poorly understood. In this study, we have followed the reaction of HCN with pristine copper, copper oxide (CuO and Cu2O) and copper@copperoxide (Cu@Cu2O) core–shell nanoparticles of well-defined size and composition. We have established a cooperative reaction mechanism where both the copper oxide shell and copper core are required for the chemisorption of HCN onto copper nanoparticle impregnants. The suitability of copper@copperoxide nanoparticles as impregnants for the removal of HCN in respirator canisters is discussed.
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Hanisha R, Hanisha R., Udayakumar R. Udayakumar R, Selvayogesh S. Selvayogesh S, Keerthivasan P. Keerthivasan P et Gnanasekaran R. Gnanasekaran R. « Anti Fungal Activity of Green Synthesized Copper Nanoparticles Using Plant Extract of Bryophyllum Pinnatum (Lam.) and Polyalthia Longifolia (Sonn.) R ». Biosciences Biotechnology Research Asia 20, no 1 (30 mars 2023) : 317–28. http://dx.doi.org/10.13005/bbra/3091.

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Plant-mediated nano-fabrication is a new area of nanotechnology that is preferred to traditional methods due to its advantages in terms of safety, cost efficiency, environmental friendliness, and biocompatibility. In the current study, copper chloride and copper sulphate are used as precursor materials to examine the effectiveness of green synthesized copper oxide nanoparticles using the plants Bryophyllum pinnatum (lam.) and Polyalthia longifolia (Sonn.) . Comparative study on the efficiency of the synthesized Copper oxide nanoparticles against each precursor has been studied. Different spectroscopic and microscopic characterization techniques such as UV- Visible spectrophotometer, X- ray powder diffraction (XRD), Fourier transformed infrared spectroscopy (FTIR), Scanning Electron Microscope (SEM) were performed to confirm the presence of copper oxide nanoparticles. UV –vis spectrophotometer results confirmed the existence of copper oxide nanoparticles using Copper chloride and Copper sulphate precursor showed absorption at 235nm and 575nm respectively. X- Ray Diffraction results showed crystalline structure of the particles with three peaks at (111), (200) & (220) which confirmed the presence of copper oxide nanoparticle for both the precursors. FTIR results supported the existence of several functional groups involved in capping, reducing, and stabilizing copper oxide nanoparticles. The SEM image showed that the copper oxide nanoparticles were spherical in shape and ranged in size from 40 to 90 nm. Further, the Anti-fungal and Anti-bacterial activity of the synthesized nanoparticle for both the copper chloride and copper sulphate precursor were studied. The Study shown maximum zone of inhibition at 100µg/ml as 18mm and 25mm respectively against Galactomyces geotrichum. As a result of the high biological potentials and powerful Antifungal activity, the green synthesized copper oxide nanoparticles can be exploited in phytopathology to combat plant infections.
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Lakshmi, Augustine, Athisayaraj Emi Princess Prasanna et Chinnapiyan Vedhi. « Synthesis, Characterisation and Capacitive Behaviour of Poly(3,4-ethylenedioxythiophene)-Copper Oxide Nanocomposites ». Advanced Materials Research 678 (mars 2013) : 273–77. http://dx.doi.org/10.4028/www.scientific.net/amr.678.273.

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Nano particles of Copper oxide and Poly(3,4-ethylenedioxythiophene)-Copper oxide nanocomposite were prepared by chemical oxidation method. The formed metal oxide nanoparticle and polymer metal oxide nanocomposites were characterized by UV–VIS, XRD, SEM and EIS studies. The UV-VIS studies of nanoparticles and nanocomposites exhibited four peaks, two peaks are sharp and centered at 280nm and 360 nm while the other two were broaden waves obtained at 780nm and 985nm. SEM image of copper oxide nanoparticles and nanocomposite exhibits sponge-like morphologies, in addition to nanospheres, nanowires, and nanotube shapes. The grain size of the metal oxide nanoparticle and polymer metaloxide nanocomposites was calculated using Scherrer’s formula. Electrochemical impedance spectroscopy (EIS) studies revealed the high conductivity nature due to the increased surface area of the nanocomposites.
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Dyah Rifani, Nabila, Rebriarina Hapsari, Tyas Prihatiningsih et Ali Khumaeni. « Synthesis, characterization, and antimicrobial properties of copper oxide nanoparticles produced by laser ablation method in chitosan solution ». Journal of Applied Research and Technology, no 2 (27 avril 2023) : 196–204. http://dx.doi.org/10.22201/icat.24486736e.2023.21.2.1596.

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Copper Oxide Nanoparticles (CuONPs) show a broad spectrum of antimicrobial activity against various species of microorganisms, including gram-positive and gram-negative fungi and bacteria, but in general gram-negative bacteria are more resistant to the effects of copper nanoparticle ions than gram-positive ones. In this work, synthesis of copper oxide nanoparticles has been carried out using laser ablation methods and the nanoparticles were applied as antibacterial agent against gram-positive bacteria Enterococcus faecalis. Experimentally, Nanoparticle synthesis was carried out using laser ablation with a power of 40 mJ. Antibacterial test with disc diffusion test using disc paper soaked in 0.1% chitosan solution (negative control), sodium hypochlorite (positive control), and copper oxide nanoparticles with a concentration of 60 ppm, 80 ppm, 100 ppm; then put into a petri dish that has been planted with the Enterococcus faecalis bacteria. Copper oxide nanoparticles were formed in chitosan as confirmed by UV-Vis, FTIR, SEM and EDX analysis. Post Hoc Tukey HSD analysis showed a significant difference in the negative control group, and the inhibition zone diameter of the treatment group was the same. The synthesis of nanoparticles using laser ablation fired at a pure copper plate succeeded in producing copper oxide nanoparticles in chitosan solvent. The firing time affects the concentration and size of the nanoparticles. More laser energy is required to produce a smaller particle size due to its antibacterial activity.
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Mohamed, HudaElslam, Unal Camdali, Atilla Biyikoglu et Metin Aktas. « Enhancing the Performance of a Vapour Compression Refrigerator System Using R134a with a CuO/CeO2 Nano-refrigerant ». Strojniški vestnik - Journal of Mechanical Engineering 68, no 6 (22 juin 2022) : 395–410. http://dx.doi.org/10.5545/sv-jme.2021.7454.

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Most studies report that dispersing nanoparticles into refrigerants and lubricating oils leads to performance improvements in refrigeration systems, due to improvements in the thermal physics properties of a pure refrigerant, which leads to reduced energy consumption. Using nanoparticles in a refrigeration system is associated with many difficulties, such as the cost of preparing and obtaining a stable and homogeneous mixture with less agglomeration and sedimentation. Most current studies focus on the use of metals, metal oxides, and a hybrid of oxides as nanoparticles in refrigeration systems. In this research, nanoparticles were prepared in an inexpensive and easy way as a single oxide and as a mixture consisting of copper and cerium oxides. The results of nanoparticle preparation using X-ray diffraction and scanning electron microscopy prove that the particles of the samples were spherical in shape, with suitable average diameters ranging from 78.95 nm, 79.9 nm, 44.15 nm and 63.3 nm for copper oxide, cerium oxide, the first mixture, and the second mixture, respectively. Cerium oxide has not been used in a refrigeration system; this study preferred the implementation of a theoretical study using Ansys Fluent software to verify the possibility of improving the performance of the refrigeration system. The results confirmed that copper oxide enhanced the coefficient of performance of the refrigeration system by 25 %, and cerium oxide succeeded in improving the performance of the. system by a lesser value. The mixture containing a higher percentage of copper oxide yielded better results.
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Samuel Paul, Akintunde Sheyi, Iliya Daniel Bangu, Sani Idris Abubakar et Muawiyya Muazu Muhammad. « Biological synthesis and characterization of copper oxide nanoparticles using aqueous Psidium guajava leave extract and study of antibacterial activity of the copper oxide nanoparticles on Escherichia coli and Staphylococcus aureus ». World Journal of Advanced Research and Reviews 9, no 1 (30 janvier 2021) : 114–20. http://dx.doi.org/10.30574/wjarr.2021.9.1.0513.

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Nanobiotechnogy has been developed to synthesized copper oxide nanoparticle. This was carried out biologically using leaf extract of Psidium guajava as a reducing and stabilizing agent. Optical property showed a color change from dark brown to gold- yellow after the addition of leaf extract. The possible functional group in the plant extract responsible for the reduction of CuONps was identified as belonging to alkyl halide group by FT-IR analysis. UV- visible spectra of copper oxide nanoparticle showed a surface plasmon resonance peak at 390nm. The biologically synthesized copper nanoparticles were tested for antibacterial activity against two human pathogens viz, Escherichia coli and Staphylococcus aureus. Biosynthesized copper nanoparticle showed clear zone of inhibition or better activity against Escherichia coli and Staphylococcus aureus.
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Cui, Wen Ying, Hyun Jin Yoo, Yun Guang Li, Changyoon Baek et Junhong Min. « Electrospun Nanofibers Embedded with Copper Oxide Nanoparticles to Improve Antiviral Function ». Journal of Nanoscience and Nanotechnology 21, no 8 (1 août 2021) : 4174–78. http://dx.doi.org/10.1166/jnn.2021.19379.

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Many studies on anti-bacterial/antiviral surfaces have been conducted to prevent epidemic spread worldwide. Several nanoparticles such as those composed of silver and copper are known to have antiviral properties. In this study, we developed copper oxide (CuO) nanoparticle-incorporated nanofibers to inactivate or remove viruses. The CuO nanoparticle-incorporated nanofiber was fabricated with a hydrophobic polymer—polyvinylpyrrolidone (PVP)—using electrospinning, and CuO nanoparticles were exposed from the PVP polymer surface by etching the nanofiber with oxygen plasma. The fabrication conditions of electrospinning and oxygen plasma etching were investigated by scanning electron microscopy (SEM), and field emission transmission electron microscopy (FETEM)/ energy dispersive spectrometry (EDS). H1N1 virus was utilized as the target sample and quantified by RT-qPCR. The antiviral efficacy of CuO nanoparticle-incorporated nanofibers was compared against bare CuO nanoparticles. Overall, 70% of the viruses were inactivated after CuO nanoparticle-incorporated nanofibers were incubated with 102 pfu/mL of H1N1 virus solution for 4 h. This indicates that the developed CuO nanoparticle-incorporated nanofibers have noticeable antiviral efficacy. As the developed CuO nanoparticle-incorporated nanofibers exerted promising antiviral effects against H1N1 virus, it is expected to benefit global health by preventing epidemic spread.
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Saputra, Ferry, Boontida Uapipatanakul, Jiann-Shing Lee, Shih-Min Hung, Jong-Chin Huang, Yun-Chieh Pang, John Emmanuel R. Muñoz, Allan Patrick G. Macabeo, Kelvin H. C. Chen et Chung-Der Hsiao. « Co-Treatment of Copper Oxide Nanoparticle and Carbofuran Enhances Cardiotoxicity in Zebrafish Embryos ». International Journal of Molecular Sciences 22, no 15 (31 juillet 2021) : 8259. http://dx.doi.org/10.3390/ijms22158259.

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The use of chemicals to boost food production increases as human consumption also increases. The insectidal, nematicidal and acaricidal chemical carbofuran (CAF), is among the highly toxic carbamate pesticide used today. Alongside, copper oxide nanoparticles (CuO) are also used as pesticides due to their broad-spectrum antimicrobial activity. The overuse of these pesticides may lead to leaching into the aquatic environments and could potentially cause adverse effects to aquatic animals. The aim of this study is to assess the effects of carbofuran and copper oxide nanoparticles into the cardiovascular system of zebrafish and unveil the mechanism behind them. We found that a combination of copper oxide nanoparticle and carbofuran increases cardiac edema in zebrafish larvae and disturbs cardiac rhythm of zebrafish. Furthermore, molecular docking data show that carbofuran inhibits acetylcholinesterase (AChE) activity in silico, thus leading to impair cardiac rhythms. Overall, our data suggest that copper oxide nanoparticle and carbofuran combinations work synergistically to enhance toxicity on the cardiovascular performance of zebrafish larvae.
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Blinov, A. V., А. А. Gvozdenko, A. B. Golik, А. А. Blinova, K. S. Slyadneva, M. A. Pirogov et D. G. Maglakelidze. « Synthesising Copper Oxide Nanoparticles and Investigating the Effect of Dispersion Medium Parameters on their Aggregate Stability ». Herald of the Bauman Moscow State Technical University. Series Natural Sciences, no 4 (103) (août 2022) : 95–109. http://dx.doi.org/10.18698/1812-3368-2022-4-95-109.

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We developed a technique for synthesising gelatin-stabilised copper oxide nanoparticles. The method behind the synthesis was direct deposition, while the copper oxide precursors used were copper sulphate, chloride and acetate. We employed gelatin as a stabiliser. We employed X-ray diffraction analysis to study the effect that the copper-containing precursor may have on the phase composition in the samples. We found that using copper(II) chloride yields two different modifications of copper(II) hydroxychloride (atacamite and clinoatacamite), while copper(II) sulphate yields brochantite. We established that copper oxide forms only when using copper(II) acetate. Dynamic light scattering data shows that a monomodal size distribution with an average hydrodynamic radius of 61 nm characterises the copper oxide nanoparticles. Investigating the effect that active acidity of the medium may have on the aggregate stability of gelatin-stabilized copper oxide nanoparticles showed that the sample is stable in the pH range of 6.8--11.98. The paper presents the mechanism behind the effect of active acidity of a medium on stability of copper oxide nanoparticles. We investigated how the ionic strength of the solution affects the stability of copper oxide nanoparticle sol. We determined that Ca2+ ions have the greatest effect on the sample
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Thèses sur le sujet "COPPER OXIDE NANOPARTICLE"

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Dywili, Nomxolisi Ruth. « Development of Metal Nanoparticle-Doped Polyanilino-Graphene Oxide High Performance Supercapacitor Cells ». University of the Western Cape, 2018. http://hdl.handle.net/11394/6251.

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Philosophiae Doctor - PhD (Chemistry)
Supercapacitors, also known as ultracapacitors or electrochemical capacitors, are considered one of the most important subjects concerning electricity or energy storage which has proven to be problematic for South Africa. In this work, graphene oxide (GO) was supported with platinum, silver and copper nanoparticles anchored with dodecylbenzenesulphonic acid (DBSA) doped polyaniline (PANI) to form nanocomposites. Their properties were investigated with different characterization techniques. The high resolution transmission electron microscopy (HRTEM) revealed GO's nanosheets to be light, flat, transparent and appeared to be larger than 1.5 ?m in thickness. This was also confirmed by high resolution scanning electron microscopy (HRSEM) with smooth surfaces and wrinkled edges observed with the energy dispersive X-ray analysis (EDX) confirming the presence of the functional groups such as carbon and oxygen. The HRTEM analysis of decorated GO with platinum, silver and copper nanoparticles (NPs) revealed small and uniformly dispersed NPs on the surface of GO with mean particle sizes of 2.3 ± 0.2 nm, 2.6 ± 0.3 nm and 3.5 ± 0.5 nm respectively and the surface of GO showed increasing roughness as observed in HRSEM micrographs. The X-ray fluorescence microscopy (XRF) and EDX confirmed the presence of the nanoparticles on the surface of GO as platinum, silver and copper which appeared in abundance in each spectra. Anchoring the GO with DBSA doped PANI revealed that single GO sheets were embedded into the polymer latex, which caused the DBSA-PANI particles to become adsorbed on their surfaces. This process then appeared as dark regions in the HRTEM images. Morphological studies by HRSEM also supported that single GO sheets were embedded into the polymer latex as composite formation appeared aggregated and as bounded particles with smooth and toothed edges.
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Roussey, Arthur. « Preparation of Copper-based catalysts for the synthesis of Silicon nanowires ». Thesis, Lyon 1, 2012. http://www.theses.fr/2012LYO10164.

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Les travaux dans cette thèse ont pour objectif la synthèse de catalyseurs (nanoparticules de cuivre) de taille contrôlée pour la synthèse de nanofils de silicium dans des conditions compatibles CMOS, c'est-à-dire en évitant l'utilisation de l'or comme catalyseur et pour des croissances basse température (<450°C). Les résultats obtenus ont permis de montrer que les techniques de chimie de surface classiquement utilisées pour la préparation de catalyseurs sur des supports 3D (silice, nitrure de titane…) sont directement applicables et transférables sur des supports 2D (wafer de silicium recouvert de films fins de SiO2, SiOx et TiN). Nous avons par exemple pu préparer des nanoparticules de cuivre de taille contrôlée (de 3 nm à 40 nm de diamètre moyen suivant les conditions expérimentales et supports). De plus, les mécanismes de formation des nanoparticules en fonction des propriétés de surface des matériaux étudiés ont été démontrés en combinant diverses techniques d'analyses de surface. La croissance de nanofils de silicium à partir de ces catalyseurs sur substrats 2D a également été réalisée avec succès dans des procédés à basse température. Il a notamment été montré l'existence d'un diamètre minimum critique à partir de laquelle la croissance basse température était possible
The work presented in this PhD thesis aimed at the preparation of copper nanoparticles of controllable size and their utilization as catalysts for the growth of silicon nanowires in a process compatible with standard CMOS technology and at low temperature (< 450°C). The growth of silicon nanowires by Chemical Vapor Deposition (CVD) via the catalytic decomposition of a silicon precursor on metallic nanoparticles at low temperature (Vapor Solid-Solid process) was demonstrated to be possible from an oxidized Cu thin film. However, this process does not allow the control over nanowires diameter, which is controlled by the diameter of the nanoparticle of catalyst. In this PhD is presented a fully bottom-up approach to prepare copper nanoparticles of controllable size directly on a surface without the help of external stabilizer by mean of surface organometallic chemistry. First, the preparation of copper nanoparticles is demonstrated on 3D substrates (silica and titanium nitride nanoparticles), along with the fine comprehension of the formation mechanism of the nanoparticles as a function of the surface properties. Then, this methodology is transferred to planar (2D) substrates typically used in microelectronics (silicon wafers). Surface structure is demonstrated to direct the Cu nanoparticles diameter between 3 to 40 nm. The similarities between the 2D and 3D substrates are discussed. Finally, the activity of the Copper nanoparticles in the growth of Silicon nanowire is presented and it is demonstrated that in our conditions a critical diameter may exist above which the growth occurs
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Carew, Alexander Jon. « Fundamental studies into the catalytic properties of metal-oxide supported gold and copper nanoparticles ». Thesis, University of Liverpool, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367710.

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Yousef, Narin. « Solution-based and flame spray pyrolysis synthesis of cupric oxide nanostructures and their potential application in dye-sensitized solar cells ». Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-119329.

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The dye sensitized solar cell (DSSC) is a promising low-cost technology alternative to conventional solar cell in certain applications. A DSSC is a photo-electrochemical photovoltaic device, mainly composed of a working electrode, a dye sensitized semiconductor layer, an electrolyte and a counter electrode. Sunlight excites the dye, producing electrons and holes that can be transported by the semiconductor and electrolyte to the external circuit, converting the sunlight into an electrical current. A material that could be useful for DSSCs is the nanoscale cupric oxide, which can act as a p-type semiconductor and has interesting properties such as low thermal emittance and relatively good electrical properties. The goal of this project was to synthesize and characterize CuO nanoparticles using three different methods and look into each products potential use and efficiency in DSSCs. The particles were synthesized using two different solution based chemical precipitation methods and a flame spray pyrolysis method, yielding nanostructures with different compositions, structures and sizes ranging from ~20 to 1000 nm. The nanoparticle powder synthesized by the flame spray pyrolysis route was tested as semiconductor layer in the working electrode of the DSSC. Current-voltage measurements presented low solar conversion efficiencies with a reversed current, meaning that the cupric oxide cells did not work in a desirable way. Further studies of the cupric oxide synthesis and its suitability in DSSCs are needed to increases the future possibilities for gaining well working p-type DSSCs with higher efficiencies.
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McManus, Paul. « Rhizosphere Interactions Between Copper Oxide Nanoparticles and Wheat Root Exudate in a Sand Matrix ; Influences on Bioavailability and Uptake ». DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/5058.

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Copper oxide nanoparticles (NPs) are used in an expanding range of industries including a potential for agricultural applications as a fungicide. Accidental spills or misapplication of CuO NPs may lead to soil contamination. Plant roots exude a wide range of organic chemicals for bioprotection and to enhance bioavailability of nutrients. Many of these chemicals are metal chelators that may increase the solubility of CuO NPs, thus enhancing the impact of these NPs on plants. This work was directed towards understanding which plant exudates force increased solubility of CuO NPs and to determine if the level of NP in the growth matrix drives a feedback effect, regarding composition and quantity of exudates. Wheat seedlings (Triticum aestivum cv Deloris) were grown in a sand matrix for 10 days after 3 days of germination. The sand was amended with sublethal doses of CuO NPs from 0 to 300 mg Cu/kg dry sand. Sand was selected as the solid growth matrix as a proxy for soil in terms of plant root morphology, mechanical impedance and water stress, while providing a low background of dissolved organic carbon for the isolation of root exudates. After plant growth, the pore water was collected from the sand by vacuum filtration and analyzed. By coupling analytic techniques including Triple Quad Mass Spectroscopy and ion chromatography with geochemical modeling, we have identified citrate and the phytosiderophore, deoxymugineic acid (DMA) as chelators that drove the majority of dissolution of CuO NPs, especially DMA at higher CuO NP doses. Altered biogeochemistry within the rhizosphere was correlated with increased plant uptake of Cu and bio-response via exudate type, quantity and metal uptake. Exposure of wheat to CuO NPs lead to dose-dependent reduction in Fe, Ca, Mg, Mn and K in roots and shoots. This work is relevant to growth of commercially important crop wheat in the presence of CuO NPs as a fertilizer, fungicide or a pollutant.
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Mårtensson, Niklas. « Optical Properties of Silica-Copper Oxide Thin Films Prepared by Spin Coating ». Thesis, Linköpings universitet, Tillämpad optik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-71188.

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Optical properties of copper oxide nanoparticles in a silica matrix thin film have been investigated. Films were prepared on Si substrates from a sol-gel by spin coating. Four samples with different thicknesses, from 14,5-109 nm, were fabricated. Optical properties were measured with Variable Angle Spectroscopic Ellipsometry. The aim of the project was to gain further understanding of these films that are interesting in applications for solar absorbers as solar selective coatings. Ellipsometricangles Ψ and Δ were measured in the wavelength range from 250-1700 nm. A dispersion model was developed and fitted to experimental data with acceptable results.
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Tejpal, Jyoti. « The use of metal and metal oxide nanoparticles against biofilms ». Thesis, De Montfort University, 2016. http://hdl.handle.net/2086/13114.

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The persistence of biofilms in hospital settings are associated with Healthcare Associated Infections (HCAI), causing increased morbidity, mortality and healthcare costs. The resistance of biofilms against commonly used hospital disinfectants has been well reported. Metal and metal oxide nanoparticles (NP) such as silver (Ag), copper (Cu), zinc oxide (ZnO) and copper oxide (CuO) exhibit antimicrobial properties against various pathogens. Methods: Biofilm formation of Pseudomonas aeruginosa and Staphylococcus aureus in a Centre for Disease Control (CDC) biofilm reactor and a 96 well plate was compared. A three stage approach including Minimum Biofilm Reduction Concentration (MBRC), R2 values and log(10) reductions was used to assess the efficacy of Ag and ZnO NPs both alone and in combination against P. aeruginosa and S. aureus biofilms. Atomic Absorption Spectroscopy (AAS), Scanning Electron Microscopy (SEM) and Confocal Laser Scanning Microscopy (CLSM) was used to further assess the antimicrobial ability of the metal and metal oxide NPs. The prevention of P. aeruginosa and S. aureus adherence on Ag and ZnO thin film coating on silicon (Si) surfaces was also investigated, as well as icaC, ebpS and fnbB gene expression in S. aureus biofilms. Results: The CDC biofilm reactor demonstrated to be the most effective method for P. aeruginosa and S. aureus biofilm production in comparison to 96 well plates, with lower standard errors of the mean (SE) and higher replicability. Individual MBRC of ZnO and Ag NPs in suspension were 256 and 50 µg/ml for P. aeruginosa and 16 and 50 µg/ml for S. aureus respectively. The concentrations in combination were reduced by at least a half, with concentrations of 32/25 µg/ml of ZnO/Ag NPs in suspension resulting in a significant (p ≤0.05) reduction of 3.77 log(10) against P. aeruginosa biofilms and 8/12 µg/ml of ZnO/Ag NPs in suspension resulted in a 3.91 log(10) (p ≤0.05) against S. aureus biofilms. Both combinations showed an additive effect. Time point analysis confirmed that a 24 hour treatment is vital for any significant (p ≤0.05) antimicrobial activity. AAS data suggested that the Ag+ ions quenched Zn2+ ions, therefore the antimicrobial efficacy of the combination is mainly due to Ag+ ions. Damage of the biofilms from Ag and ZnO NPs was observed in the SEM imaging and energy dispersive X-ray (EDX) analysis confirmed the adherence of Zn and Ag within the biofilms. CLSM imaging showed dead (red) cells of P. aeruginosa and S. aureus biofilms throughout the depth of the biofilm. P. aeruginosa formation was reduced by 1.41 log(10) and 1.43 log(10) on Ag and ZnO thin film coatings respectively. For S. aureus, a reduction of 1.82 log(10) and 1.65 log(10) was obtained for Ag and ZnO coating respectively. Only low levels of ribonucleic acid (RNA) were achieved so no further gene analysis could occur. Conclusion: Reductions of ≥3 log(10) were observed for P. aeruginosa and S. aureus biofilm treatment with ZnO/Ag NP suspensions. It can be concluded that the ZnO/Ag NP suspensions had greater antimicrobial activity than Ag and ZnO coated surfaces owing to large concentrations of Ag+ and Zn2+ ions acting upon the biofilms. The slower release of ions from coated surfaces suggest an inadequate concentration of ions in the media, which are therefore unable to prevent biofilm formation as rapidly as NP suspensions, however provide a sustained release of ions over time. The results from this investigation propose that Ag and ZnO NPs in suspension could be a potential alternative to disinfectants for use in nosocomial environments against P. aeruginosa and S. aureus biofilms.
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Hortin, Joshua. « Behavior of Copper Oxide Nanoparticles in Soil Pore Waters as Influenced by Soil Characteristics, Bacteria, and Wheat Roots ». DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6895.

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The goal of this project was to study the behavior of copper oxide nanoparticles in soil environments. Copper oxide nanoparticles have antimicrobial properties and may also be used in agricultural settings to provide a source of copper for plant health, but accidental or misapplication of these nanoparticles to soil may be damaging to the plant and its associated bacteria. Dissolved soil organic matter that is present in soil pore waters dissolved nanoparticles, but did not dissolve the expected amounts from a geochemical model because the geochemical model did not take into account surface chemistry or coating of the nanoparticles by dissolved organic matter. Wheat grown in soil pore water increased the solubility of the nanoparticles. The nanoparticles and dissolved copper were harmful to wheat, but dissolved soil organic matter remediated a portion of the damage. These studies were conducted with Utah soils and wheat, a highly valuable Utah crop. These results suggest that contamination of soils by copper oxide nanoparticles will be partially mitigated by the organic matter content of the soil. Producers of fertilizers and fungicides may use various forms of organic matter to deliver products that are targeted to specific plants or pathogens and avoid damage to non-target organisms.
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Izaak, T. I., D. О. Martynova, V. V. Maas, E. М. Slavinskaya, А. I. Boronin et Y. W. Chen. « Synthesis and Properties of Ag / CuO / SiO2 Nanocomposites ». Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35611.

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In this paper the composites Ag / SiO2 with regularly distributed in bulk matrix silver and copper oxide nanoparticles were synthesized. Herewith, copper ions was introduced into porous support at the stage of sol-gel synthesis. Sample Ag / CuO / SiO2 was tested by the catalytic reaction of CO oxidation and com-pared with Ag / SiO2. It was revealed that sample with introduced copper show lower activity .This fact can be explained by formation of silver cuprate during preparation of composite Ag / CuO / SiO2. Treatment by reaction mixture (CO and O2) led to release of silver in ionic, clusters and metal states that increased cata-lytic activity of the composite. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35611
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Bottois, Clément. « Nanoparticules pour la réalisation de couches de transport de trous appliquées au photovoltaïque organique ». Thesis, Université Grenoble Alpes (ComUE), 2015. http://www.theses.fr/2015GREAI025/document.

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Dans les cellules photovoltaïques organiques, le matériau utilisé pour le transport de trous entre la couche active et l'électrode, est généralement un polymère dopé, dont la stabilité peut être problématique. L'objectif de cette thèse a été de développer des matériaux inorganiques, a priori plus stables, pour remplacer les couches de polymères de transport de trous, tout en restant compatible avec les méthodes de dépôts par voie liquide. L'utilisation de nanoparticules dispersées en solution a été choisie car cela permet le dépôt à basse température, sans nécessité de conversion vers une couche fonctionnelle, contrairement aux voies sol-gel. Le premier objectif de ce travail a donc été l'obtention de nanoparticules d'oxyde de tungstène, hydraté ou non, et de thiocyanate de cuivre. Une synthèse de chauffage assisté par micro-ondes a été utilisée pour l'oxyde de tungstène, permettant d'obtenir des nanoparticules de 30 nm et monodisperses. Pour le thiocyanate de cuivre, il a été choisi de travailler par broyage. Les paramètres du broyage ont été optimisés pour obtenir des particules avec la plus faible distribution en taille possible. Le dépôt de ces dispersions de nanoparticules a permis l'obtention de couches minces et la caractérisation de leurs propriétés optoélectroniques, et notamment du travail de sortie, qui s'est révélé adapté pour une utilisation en dispositif. Des cellules solaires organiques de structures standard et inverse incorporant ces matériaux ont ensuite été réalisées. De bonnes performances ont été obtenues avec une couche active à base de P3HT, notamment en structure inverse où la possibilité d'utiliser le thiocyanate de cuivre a été démontrée pour la première fois. Le suivi des performances sous éclairement et atmosphère contrôlée a également été effectué et a montré un vieillissement rapide pour ces cellules comparées aux cellules de référence à couche de transport de trous polymère
In organic solar cells, a doped polymer is the most used material for hole transport between the active layer and the electrode, but his stability can be an important issue. The goal of this PhD thesis was to develop inorganic materials, expected to be more stable, in order to replace polymer based hole transporting layers. Another requirement was to keep the compatibility with solution-based deposition methods. The target was to develop nanoparticle dispersions, deposited at low temperature and giving directly a functional layer, without the need of further treatments which are usually required via sol-gel processes. A first objective of the present work was thus the elaboration of nanoparticles of tungsten oxide, hydrated or non-hydrated, and copper thiocyanate. A microwave-assisted heating synthesis has been used for tungsten oxide, leading to mono-dispersed particles around 30 nm. Concerning copper thiocyanate, a ball milling technique has been chosen. The process parameters have been optimized to obtain nanoparticles to narrow the size distribution as much as possible. The deposition of the nanoparticles has allowed the formation of thin layers and the characterization of their optoelectronic properties, such as work function, which was shown to be a relevant parameter for a use in devices. Organic solar cells with standard or inverted structures have been fabricated using these materials as a hole transporting layer. Good photovoltaic performances have been obtained, especially in the inverted structure, in which the possibility to use copper thiocyanate has been demonstrated for the first time. Ageing experiments under light in a controlled atmosphere have also been carried out and have shown a rapid drop in performances for these cells compared to cells incorporating polymer based hole transport layers
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Chapitres de livres sur le sujet "COPPER OXIDE NANOPARTICLE"

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Okanigbe, Daniel Ogochukwu. « Extraction of Copper Oxide (II) : Copper Oxide Nanoparticles ». Dans Resource Recovery and Recycling from Waste Metal Dust, 107–31. Cham : Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-22492-8_6.

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Das, Dudul, et Pankaj Kalita. « Performance Improvement of a Novel Flat Plate Photovoltaic Thermal (PV/T) System Using Copper Oxide Nanoparticle—Water as Coolant ». Dans Springer Proceedings in Energy, 97–104. Cham : Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-63085-4_14.

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Arun Kumar, A., R. Subramaniyan@Raja, G. Padmasree, Kodumuri Veerabhadra Rao, K. Anuradha et A. Rathika. « Copper Oxide Nanoparticles for Energy Storage Applications ». Dans Materials for Sustainable Energy Storage at the Nanoscale, 233–40. Boca Raton : CRC Press, 2023. http://dx.doi.org/10.1201/9781003355755-20.

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Saha, Ishita, Parimal Karmakar et Debalina Bhattacharya. « Fungi-Mediated Fabrication of Copper Nanoparticles and Copper Oxide Nanoparticles, Physical Characterization and Antimicrobial Activity ». Dans Mycosynthesis of Nanomaterials, 112–25. Boca Raton : CRC Press, 2023. http://dx.doi.org/10.1201/9781003327387-7.

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Ibrahim, Suriani, Nurul Zariyah Jakaria@Zakaria, Shaifulazuar Rozali, Nik Nazri Nik Ghazali, Mohd Sayuti Ab Karim et Mohd Faizul Mohd Sabri. « Biosynthesis of Copper Oxide Nanoparticles Using Camellia Sinensis Plant Powder ». Dans Advances in Material Sciences and Engineering, 233–38. Singapore : Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-8297-0_26.

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Singh, Ravindra Pratap. « Potential of Biogenic Plant-Mediated Copper and Copper Oxide Nanostructured Nanoparticles and Their Utility ». Dans Plant Nanobionics, 115–76. Cham : Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-16379-2_5.

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Adhikari, Tapan, Garima Dube, S. Kundu et A. K. Patra. « Impact of Copper Oxide Nanoparticles on Growth of Different Bacterial Species ». Dans Water Science and Technology Library, 47–55. Singapore : Springer Singapore, 2017. http://dx.doi.org/10.1007/978-981-10-5798-4_5.

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Joshi, Archana, Ashutosh Sharma, Rakesh Kumar Bachheti, Azamal Husen et Vinod Kumar Mishra. « Plant-Mediated Synthesis of Copper Oxide Nanoparticles and Their Biological Applications ». Dans Nanomaterials and Plant Potential, 221–37. Cham : Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-05569-1_8.

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Alcalà, Jordi, Mercè Roig, Sergi Martín, Aleix Barrera, Alejandro Fernández-Rodríguez, Alberto Pomar, Lluís Balcells, Mariona Coll, Narcís Mestres et Anna Palau. « Potential of Copper Oxide High-Temperature Superconductors for Tailoring Ferromagnetic Spin Textures ». Dans Surfaces and Interfaces of Metal Oxide Thin Films, Multilayers, Nanoparticles and Nano-composites, 167–82. Cham : Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-74073-3_7.

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Khan, K. A., M. Shaiful Islam, Abdul Awal, M. N. Islam Khan et A. K. M. Atique Ullah. « Studies on Performances of Copper Oxide Nanoparticles from Catharanthus Roseus Leaf Extract ». Dans Lecture Notes in Electrical Engineering, 179–90. Singapore : Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-1570-2_17.

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Actes de conférences sur le sujet "COPPER OXIDE NANOPARTICLE"

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Zlebic, C., Lj Zivanov, N. Blaz, M. Kisic et M. Lukovic. « Characterization of Printed Humidity Sensor Based on Nanoparticle Copper Oxide ». Dans 2020 23rd International Symposium on Design and Diagnostics of Electronic Circuits & Systems (DDECS). IEEE, 2020. http://dx.doi.org/10.1109/ddecs50862.2020.9095702.

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Fujino, M., M. Akaike, N. Matsuoka et T. Suga. « Reduction Reaction Analysis of Nanoparticle Copper Oxide by Formic Acid ». Dans 2016 International Conference on Solid State Devices and Materials. The Japan Society of Applied Physics, 2016. http://dx.doi.org/10.7567/ssdm.2016.m-5-03.

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McCants, Dale A., Jamil A. Khan, Andrew M. Hayes et Aly Shaaban. « Evaluating the Thermal Characteristics of Copper-II and Zinc-Oxide Nanofluids Flowing Over a Heated Flat Plate ». Dans ASME 2008 Heat Transfer Summer Conference collocated with the Fluids Engineering, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/ht2008-56141.

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Thermal characteristics of CopperII and Zinc-Oxide nanofluids have been investigated for flow over a heated flat plate. Fluid containing different volume-percents nanoparticles flow over a heated flat plate at specified laminar flow velocities. The heated plate experienced a constant heat flux from cartridge heaters spaced evenly along the length of the plate. The flow channel’s cross-sectional area was a square of dimensions 5cm × 5cm. Investigation of the heat transfer occurring in a plane along the centerline of the plate in the direction of the flow was performed. The heat transfer coefficients were calculated and plotted verses the Reynolds number and compared with the results obtained from distilled de-ionized water. Nanoparticle size from the fluids was investigated to inspect for possible agglomeration using both a transmission electron microscope (TEM) and a dynamic light scattering system (DLS).
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Sofiya Dayana, K., et R. Jothimani. « Preparation and characterization of copper oxide nanoparticle-determination of its structural and optical properties ». Dans 2ND INTERNATIONAL CONFERENCE ON MATERIALS FOR ENERGY AND ENVIRONMENT 2020. AIP Publishing, 2023. http://dx.doi.org/10.1063/5.0140312.

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Torii, Shuichi. « Turbulent Thermal Fluid Flow Transport Phenomena of Aqueous Suspensions of Nano-Particles ». Dans ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18090.

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The aim of the present study is to investigate the thermal fluid flow transport phenomenon of nanofluids in the heated horizontal circular tube. Consideration is given to the effects of volume fraction of the nanoparticle and Reynolds number on the turbulent heat transfer and pressure loss. Diamond, alumina (Al2O3) and oxide copper (CuO) are employed here as nanoparticles. It is found that (i) the viscosity of nanofluids increases with an increase in the volume fraction of nanoparticles dispersed in the working fluid, (ii) the pressure loss of nanofluids increases slightly in comparison with that of pure fluid and (iii) enhancement heat transfer performance is caused by suspending nanoparticles except for the case of large particle aggregation.
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Kedzierski, Mark A. « Effect of CuO Nanoparticle Concentration on R134A/Lubricant Pool Boiling Heat Transfer ». Dans ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer. ASMEDC, 2008. http://dx.doi.org/10.1115/mnht2008-52116.

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This paper quantifies the influence of copper (II) oxide (CuO) nanoparticle concentration on the boiling performance of R134a/polyolester mixtures on a roughened, horizontal flat surface. Nanofluids are liquids that contain dispersed nanosize particles. Two lubricant based nanofluids (nanolubricants) were made with a synthetic polyolester and 30 nm diameter CuO particles to a 4% and a 2% volume fraction, respectively. As reported in a previous study for the 4% volume fraction nanolubricant, a 0.5% nanolubricant mass fraction with R134a resulted in a heat transfer enhancement relative to the heat transfer of pure R134a/polyolester (99.5/0.5) of between 50% and 275%. The same study had shown that increasing the mass fraction of the 4% volume fraction nanolubricant resulted in smaller, but significant, boiling heat transfer enhancements. The present study shows that use of a nanolubricant with half the concentration of CuO nanoparticles (2% by volume) resulted in either no improvement or boiling heat transfer degradations with respect to the R134a/polyolester mixtures without nanoparticles. Consequently, significant refrigerant/lubricant boiling heat transfer enhancements are possible with nanoparticles; however, the nanoparticle concentration is an important determining factor. Further research with nanolubricants and refrigerants are required to establish a fundamental understanding of the mechanisms that control nanofluid heat transfer.
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Torii, Shuichi. « Thermal Transport Phenomenon in Circular Pipe Flow Using Different Nanofluids ». Dans ASME 2013 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/ipack2013-73043.

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The aim of the present study is to investigate the thermal fluid flow transport phenomenon of nanofluids in the heated horizontal circular tube. Consideration is given to the effects of volume fraction of the nanoparticle on the laminar heat transfer and thermal properties. Alumina (Al2O3) and oxide copper (CuO) are employed here as nanoparticles. It is found from the study that (1) the viscosity ratio of nanofluids increases in accordance with an increase of the volume fraction of the nanoparticles, (2) the nanofluids have substantially higher value of Nusselt number than the same liquids without nanoparticles and the Nusselt number of nanofluids increase with an increase of the Reynolds number, and (3) the dispersibility of particle in the nanofluid becomes worse slightly with an increase of the volume fraction of the nanoparticles.
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Fan, Liwu, et J. M. Khodadadi. « Experimental Verification of Expedited Freezing of Nanoparticle-Enhanced Phase Change Materials (NEPCM) ». Dans ASME/JSME 2011 8th Thermal Engineering Joint Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/ajtec2011-44165.

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Highly-conductive nano-sized particles are dispersed into phase change materials (PCM) to improve their effective thermal conductivity, thus leading to suspensions that are referred to as nanoparticle-enhanced PCM (NEPCM). In order to assess the extent of expedited phase change due to the enhanced thermal conductivity, the one-dimensional unidirectional freezing process of NEPCM in a finite slab was investigated experimentally. Thermocouple readings were recorded at several equally-spaced locations along the freezing direction in order to monitor the progress of the freezing front. As an example, cyclohexane (C6H12) and copper oxide (CuO) nanoparticles were chosen to develop the NEPCM with three different volume fractions (0.5, 1.0, and 2.0 vol%). It was shown that the freezing rate for the 0.5 vol% NEPCM is considerably raised as compared to pure cyclohexane. However, further increase of the fraction of nanoparticles to 1.0 and 2.0 vol% did not linearly expedite freezing. Significant sedimentation of nanoparticles was observed for the 2.0 vol% NEPCM. Additionally, in this case the undesirable supercooling phenomenon was enhanced, which suppresses the growth rate of the solidified NEPCM.
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Khodadadi, J. M., et Liwu Fan. « Expedited Freezing of Nanoparticle-Enhanced Phase Change Materials (NEPCM) Exhibited Through a Simple 1-D Stefan Problem Formulation ». Dans ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/ht2009-88409.

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An analytic/integral approach is utilized to solve a model 1-dimensional Stefan problem for a nanofluid that undergoes freezing. Initially, the isothermal nanofluid is contained in a finite slab. During the freezing process, the traveling interface separates the liquid and solid phases that possess their respective thermophysical properties. The most favorable feature of this model is that the thermal property jumps between the liquid and solid phases are accounted for. The problem is made dimensionless and is shown to depend on the thermal conductivity ratio, thermal diffusivity ratio, Stefan (Ste) and subcooling numbers. The energy equation within the solid layer is solved exactly and that of the liquid layer is solved using the integral method. The instantaneous interface position and the moving front velocity are obtained and the total freezing time is then determined. Combinations of two base PCM (water and cyclohexane) and four nanoparticles (alumina, copper, copper oxide and titanium oxide) are chosen for demonstration purposes. The thermal properties of the resulting nanofluids as a function of the volume fraction were determined using models proposed in the literature. The results show that the dimensionless freezing time is independent of the nanofluid constituents and only depends on the volume fraction. Keeping everything else the same, the freezing time is shown to decrease as the volume fraction of the nanoparticle is raised.
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O’Hanley, Harry, Jacopo Buongiorno, Thomas McKrell et Lin-wen Hu. « Measurement and Model Correlation of Specific Heat Capacity of Water-Based Nanofluids With Silica, Alumina and Copper Oxide Nanoparticles ». Dans ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-62054.

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Nanofluids are being considered for heat transfer applications. However, their thermo-physical properties are poorly known. Here we focus on nanofluid specific heat capacity. Currently, there exist two models to predict a nanofluid’s specific heat capacity as a function of nanoparticle concentration and material. Model I is a straight volume-weighted average; Model II is based on the assumption of thermal equilibrium between the particles and the surrounding fluid. These two models give significantly different predictions for a given system. Using differential scanning calorimetry, the specific heat capacities of water based silica, alumina, and copper oxide nanofluids were measured. Nanoparticle concentrations were varied between 5wt% and 50wt%. Test results were found to be in excellent agreement with Model II, while the predictions of Model I deviate very significantly from the data.
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Rapports d'organisations sur le sujet "COPPER OXIDE NANOPARTICLE"

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Chefetz, Benny, Baoshan Xing, Leor Eshed-Williams, Tamara Polubesova et Jason Unrine. DOM affected behavior of manufactured nanoparticles in soil-plant system. United States Department of Agriculture, janvier 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.
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