Academic literature on the topic 'ZnO NPs'
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Journal articles on the topic "ZnO NPs"
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Ivanova, Iliana A., Elitsa L. Pavlova, Aneliya S. Kostadinova, Radostina D. Toshkovska, Lyubomira D. Yocheva, Kh El-Sayed, Mohamed A. Hassan, Heba El-Sayed El-Zorkany, and Hisham A. Elshoky. "Investigation of Biological and Prooxidant Activity of Zinc Oxide Nanoclusters and Nanoparticles." Acta Chimica Slovenica 69, no. 3 (September 26, 2022): 722–33. http://dx.doi.org/10.17344/acsi.2021.7337.
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Zinc oxide (ZnO) nanomaterials offer some promising antibacterial effects. In this study, a new form of ZnO is synthesized, named ZnO nanocluster bars (NCs). Herein, ZnO NCs, ZnO nanoparticles (NPs), ZnO coated with silica (ZnOSiOA, ZnO-SiOB), and SiO2 NPs were prepared, characterized, and their antimicrobial and prooxidant activity were tested. The prooxidant activity of all nanomaterials was studied according to free-radical oxidation reactions (pH 7.4 and pH 8.5) in chemiluminescent model systems. Each form of new synthesized ZnO nanomaterials exhibited a unique behavior that varied from mild to strong prooxidant properties in the Fenton`s system. ZnO NPs and ZnO NCs showed strong antibacterial effects, ZnO-SiOA NPs did not show any antibacterial activity representing biocompatibility. All tested NMs also underwent oxidation by H2O2. ZnO NCs and ZnO NPs exhibited strong oxidation at pH 8.5 in the O2 –. generating system. While, SiO2, ZnO-SiOA and ZnO-SiOB possessed pronounced 60–80% antioxidant effects, SiO2 NPs acted as a definitive prooxidant which was not observed in other tests. ZnO NCs are strongly oxidized, assuming that ZnO NCs provide a slower release of ZnO, which leads to having a stronger effect on bacterial strains. Thus, ZnO NCs are an important antibacterial agent that could be an emergent replacement of traditional antibiotics.
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Yang, Yuran, Can Zhang, Kaili Li, and Zhenlun Li. "Fe2+ Alleviated the Toxicity of ZnO Nanoparticles to Pseudomonas tolaasii Y-11 by Changing Nanoparticles Behavior in Solution." Microorganisms 9, no. 11 (October 20, 2021): 2189. http://dx.doi.org/10.3390/microorganisms9112189.
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The negative effect of ZnO nanoparticles (ZnO-NPs) on the biological removal of nitrate (NO3−) has received extensive attention, but the underlying mechanism is controversial. Additionally, there is no research on Fe2+ used to alleviate the cytotoxicity of NPs. In this paper, the effects of different doses of ZnO-NPs on the growth and NO3− removal of Pseudomonas tolaasii Y-11 were studied with or without Fe2+. The results showed that ZnO-NPs had a dose-dependent inhibition on the growth and NO3− removal of Pseudomonas tolaasii Y-11 and achieved cytotoxic effects through both the NPs themselves and the released Zn2+. The addition of Fe2+ changed the behavior of ZnO-NPs in an aqueous solution (inhibiting the release of toxic Zn2+ and promoting the aggregation of ZnO-NPs), thereby alleviating the poisonous effect of ZnO-NPs on the growth and nitrogen removal of P. tolaasii Y-11. This study provides a theoretical method for exploring the mitigation of the acute toxicity of ZnO-NPs to denitrifying microorganisms.
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Li, Junlin, Xiangfei Li, Dong Liang, Xiaojuan Zhang, Qing Lin, and Lingyun Hao. "Preparation and Antibacterial Performances of Electrocatalytic Zinc Oxide Nanoparticles with Diverse Morphologies." Journal of Biomedical Nanotechnology 17, no. 9 (September 1, 2021): 1824–29. http://dx.doi.org/10.1166/jbn.2021.3144.
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This study exploits the potential of zinc oxide nanoparticles (ZnO-NPs) with diverse morphologies as catalysts and antibacterial agent. Spherical ZnO-NPs, rod-shaped ZnO-NPs and flower-shaped ZnO-NPs were prepared by microemulsion method, solvent heat method and hydrothermal method, respectively. The structural characterizations of samples were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. XRD results revealed the formation of spherical ZnO-NPs, rod-shaped ZnO-NPs and flower-shaped ZnO-NPs were all wurtzite crystal structure. SEM results showed that spherical ZnO-NPs had an average particle size of 30–40 nm, rod-shaped ZnO-NPs were about 500 nm long and 100 nm wide with obvious hexagonal crystals. Flower-shaped ZnO-NPs had a three-dimensional appearance with obvious petals. Results of electrochemical HER (Hydrogen evolution reaction) experiments revealed that spherical ZnO-NPs exhibited the highest electrocatalytic activity at the lowest potential voltage due to their largest specific surface area. The antibacterial property of ZnO-NPs samples were studied by the optical density method and disc diffusion method. All samples had antibacterial effects against E. coli. and flower-shaped ZnO-NPs showed the best antibacterial activity due to the largest surface area in comparison with spherical ZnO-NPs and rod-shaped ZnO-NPs, which promised the maximum Zn2+ release as bactericide mechanism that registered in the case of different ZnO-NPs morphologies.
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Larsen, Søren T., Emilie Da Silva, Jitka S. Hansen, Alexander C. Ø. Jensen, Ismo K. Koponen, and Jorid B. Sørli. "Acute Inhalation Toxicity After Inhalation of ZnO Nanoparticles: Lung Surfactant Function Inhibition In Vitro Correlates With Reduced Tidal Volume in Mice." International Journal of Toxicology 39, no. 4 (July 2020): 321–27. http://dx.doi.org/10.1177/1091581820933146.
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People can be exposed to zinc oxide (ZnO) by inhalation of consumer products or during industrial processes. Zinc oxide nanoparticle (NP) exposure can induce acute inhalation toxicity. The toxicological mechanisms underlying the acute effects on the lungs have long focused on the phagolysosomal dissolution of ZnO NPs in macrophages followed by the release of free Zn2+ ions. However, we postulate an alternative mechanism based on the direct interaction of ZnO NPs with the lung surfactant (LS) layer covering the inside of the alveoli. Therefore, we tested the effect of ZnO NPs and Zn2+ ions on the function of LS in vitro using the constrained drop surfactometer. We found that the ZnO NPs inhibited the LS function, whereas Zn2+ ions did not. To examine the role of lung macrophages in the acute toxicity of inhaled ZnO NPs, mice were treated with Clodrosome, a drug that depletes alveolar macrophages, or Encapsome, the empty carrier of the drug. After macrophage depletion, the mice were exposed to an aerosol of ZnO NPs in whole body plethysmographs recording breathing patterns continuously. Mice in both groups developed shallow breathing (reduced tidal volume) shortly after the onset of exposure to ZnO NPs. This suggests a macrophage-independent mechanism of induction. This study shows that acute inhalation toxicity is caused by ZnO NP interaction with LS, independently of NP dissolution in macrophages.
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Alhujaily, Muhanad, Majid S. Jabir, Uday M. Nayef, Taha M. Rashid, Ghassan M. Sulaiman, Khalil A. A. Khalil, Muntadher I. Rahmah, Mazin A. A. Najm, Rihab Jabbar, and Sabrean F. Jawad. "Au/ZnO Nanocomposites Prepared by Laser Ablation for Enhancement of Antibacterial Activity and Cytotoxic Properties against Cancer Cells." Metals 13, no. 4 (April 9, 2023): 735. http://dx.doi.org/10.3390/met13040735.
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This study presents a comprehensive look into the potential therapeutic, antibacterial, and anticancer properties of a nanocomposite (NC) of gold (Au) and zinc oxide (ZnO). In this study, we analyzed the adherence between Au nanoparticles (NPs) and ZnO NPs. X-ray diffraction analysis showed high crystallinity and small crystallite sizes of Au NPs and ZnO NPs, while transmission electron microscopy showed spherical NPs. Furthermore, histogram analysis showed that the average particle size of Au NPs is 27 nm, while that of ZnO NPs is 35 nm. The adherence of ZnO NPs on the surface of Au NPs increased their combined particle size to 51 nm and revealed a high-population core-shell structure. The activity of Au/ZnO NCs against Escherichia coli was more potent when compared to that of elemental Au and ZnO NPs alone. The cytotoxic effects of Au NPs, ZnO NPs, and Au/ZnO NCs against human breast cancer cells (AMG13) and human esophageal adenocarcinoma cancer cells (SK-GT4) were investigated in this study. We found that AMG13 is more sensitive than SK-GT4 to the activity of Au/ZnO NCs. The cytotoxicity of Au/ZnO NCs against AMG13 was 89%, while that against SK-GT4 was 85%. Less cytotoxic effects were recorded against normal cells (MCF7) when compared with those of cancer cells. Based on these findings, the synthesized Au/ZnO NCs could be used as a promising strategy for biomedical applications.
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Liang, Yan, Aili Simaiti, Mingxuan Xu, Shenchong Lv, Hui Jiang, Xiaoxiang He, Yang Fan, et al. "Antagonistic Skin Toxicity of Co-Exposure to Physical Sunscreen Ingredients Zinc Oxide and Titanium Dioxide Nanoparticles." Nanomaterials 12, no. 16 (August 12, 2022): 2769. http://dx.doi.org/10.3390/nano12162769.
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Being the main components of physical sunscreens, zinc oxide nanoparticles (ZnO NPs) and titanium dioxide nanoparticles (TiO2 NPs) are often used together in different brands of sunscreen products with different proportions. With the broad use of cosmetics containing these nanoparticles (NPs), concerns regarding their joint skin toxicity are becoming more and more prominent. In this study, the co-exposure of these two NPs in human-derived keratinocytes (HaCaT) and the in vitro reconstructed human epidermis (RHE) model EpiSkin was performed to verify their joint skin effect. The results showed that ZnO NPs significantly inhibited cell proliferation and caused deoxyribonucleic acid (DNA) damage in a dose-dependent manner to HaCaT cells, which could be rescued with co-exposure to TiO2 NPs. Further mechanism studies revealed that TiO2 NPs restricted the cellular uptake of both aggregated ZnO NPs and non-aggregated ZnO NPs and meanwhile decreased the dissociation of Zn2+ from ZnO NPs. The reduced intracellular Zn2+ ultimately made TiO2 NPs perform an antagonistic effect on the cytotoxicity caused by ZnO NPs. Furthermore, these joint skin effects induced by NP mixtures were validated on the epidermal model EpiSkin. Taken together, the results of the current research contribute new insights for understanding the dermal toxicity produced by co-exposure of different NPs and provide a valuable reference for the development of formulas for the secure application of ZnO NPs and TiO2 NPs in sunscreen products.
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Scherzad, Agmal, Till Meyer, Norbert Kleinsasser, and Stephan Hackenberg. "Molecular Mechanisms of Zinc Oxide Nanoparticle-Induced Genotoxicity." Materials 10, no. 12 (December 14, 2017): 1427. http://dx.doi.org/10.3390/ma10121427.
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Background: Zinc oxide nanoparticles (ZnO NPs) are among the most frequently applied nanomaterials in consumer products. Evidence exists regarding the cytotoxic effects of ZnO NPs in mammalian cells; however, knowledge about the potential genotoxicity of ZnO NPs is rare, and results presented in the current literature are inconsistent. Objectives: The aim of this review is to summarize the existing data regarding the DNA damage that ZnO NPs induce, and focus on the possible molecular mechanisms underlying genotoxic events. Methods: Electronic literature databases were systematically searched for studies that report on the genotoxicity of ZnO NPs. Results: Several methods and different endpoints demonstrate the genotoxic potential of ZnO NPs. Most publications describe in vitro assessments of the oxidative DNA damage triggered by dissoluted Zn2+ ions. Most genotoxicological investigations of ZnO NPs address acute exposure situations. Conclusion: Existing evidence indicates that ZnO NPs possibly have the potential to damage DNA. However, there is a lack of long-term exposure experiments that clarify the intracellular bioaccumulation of ZnO NPs and the possible mechanisms of DNA repair and cell survival.
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Valdiglesias, Vanessa, Anabel Alba-González, Natalia Fernández-Bertólez, Assia Touzani, Lucía Ramos-Pan, Ana Teresa Reis, Jorge Moreda-Piñeiro, Julián Yáñez, Blanca Laffon, and Mónica Folgueira. "Effects of Zinc Oxide Nanoparticle Exposure on Human Glial Cells and Zebrafish Embryos." International Journal of Molecular Sciences 24, no. 15 (August 1, 2023): 12297. http://dx.doi.org/10.3390/ijms241512297.
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Zinc oxide nanoparticles (ZnO NPs) are among the most widely used nanomaterials. They have multiple applications in cosmetics, textiles, paints, electronics and, recently, also in biomedicine. This extensive use of ZnO NPs notably increases the probability that both humans and wildlife are subjected to undesirable effects. Despite being among the most studied NPs from a toxicological point of view, much remains unknown about their ecotoxicological effects or how they may affect specific cell types, such as cells of the central nervous system. The main objective of this work was to investigate the effects of ZnO NPs on human glial cells and zebrafish embryo development and to explore the role of the released Zn2+ ions in these effects. The effects on cell viability on human A172 glial cells were assessed with an MTT assay and morphological analysis. The potential acute and developmental toxicity was assessed employing zebrafish (Danio rerio) embryos. To determine the role of Zn2+ ions in the in vitro and in vivo observed effects, we measured their release from ZnO NPs with flame atomic absorption spectrometry. Then, cells and zebrafish embryos were treated with a water-soluble salt (zinc sulfate) at concentrations that equal the number of Zn2+ ions released by the tested concentrations of ZnO NPs. Exposure to ZnO NPs induced morphological alterations and a significant decrease in cell viability depending on the concentration and duration of treatment, even after removing the overestimation due to NP interference. Although there were no signs of acute toxicity in zebrafish embryos, a decrease in hatching was detected after exposure to the highest ZnO NP concentrations tested. The ability of ZnO NPs to release Zn2+ ions into the medium in a concentration-dependent manner was confirmed. Zn2+ ions did not seem entirely responsible for the effects observed in the glial cells, but they were likely responsible for the decrease in zebrafish hatching rate. The results obtained in this work contribute to the knowledge of the toxicological potential of ZnO NPs.
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Gurugubelli, Thirumala Rao, R. V. S. S. N. Ravikumar, and Ravindranadh Koutavarapu. "Enhanced Photocatalytic Activity of ZnO–CdS Composite Nanostructures towards the Degradation of Rhodamine B under Solar Light." Catalysts 12, no. 1 (January 12, 2022): 84. http://dx.doi.org/10.3390/catal12010084.
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A simple chemical precipitation route was utilized for the synthesis of ZnO nanoparticles (NPs), CdS NPs and ZnO–CdS nanocomposites (NCs). The synthesized nanostructures were examined for the crystal structure, morphology, optical properties and photodegradation activity of rhodamine B (RhB) dye. The ZnO–CdS NCs showed a mixed phase of hexagonal wurtzite structure for both ZnO NPs and CdS NPs. Pure ZnO NPs and CdS NPs possessed bandgaps of 3.2617 and 2.5261 eV, respectively. On the other hand, the composite nanostructures displayed a more narrow bandgap of 2.9796 eV than pure ZnO NPs. When compared to bare ZnO NPs, the PL intensity of near-band-edge emission at 381 nm was practically suppressed, suggesting a lower rate of photogenerated electron–hole (e−/h+) pairs recombination, resulting in enhanced photocatalytic activity. Under solar light, the composite nanostructures displayed a photodegradation efficiency of 98.16% towards of RhB dye. After four trials, the structural stability of ZnO–CdS NCs was verified.
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de la Rosa, Guadalupe, Martha Laura López-Moreno, David de Haro, Cristian E. Botez, José R. Peralta-Videa, and Jorge L. Gardea-Torresdey. "Effects of ZnO nanoparticles in alfalfa, tomato, and cucumber at the germination stage: Root development and X-ray absorption spectroscopy studies." Pure and Applied Chemistry 85, no. 12 (December 1, 2013): 2161–74. http://dx.doi.org/10.1351/pac-con-12-09-05.
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Past reports indicate that some nanoparticles (NPs) affect seed germination; however, the biotransformation of metal NPs is still not well understood. This study investigated the toxicity on seed germination/root elongation and the uptake of ZnO NPs and Zn2+ in alfalfa (Medicago sativa), cucumber (Cucumis sativus), and tomato (Solanum lycopersicum) seedlings. Seeds were treated with ZnO NPs at 0–1600 mg L–1 as well as 0–250 mg L–1 Zn2+ for comparison purposes. Results showed that at 1600 mg L–1 ZnO NPs, germination in cucumber increased by 10 %, and alfalfa and tomato germination were reduced by 40 and 20 %, respectively. At 250 mg Zn2+ L–1, only tomato germination was reduced with respect to controls. The highest Zn content was of 4700 and 3500 mg kg–1 dry weight (DW), for alfalfa seedlings germinated in 1600 mg L–1 ZnO NPs and 250 mg L–1 Zn2+, respectively. Bulk X-ray absorption spectroscopy (XAS) results indicated that ZnO NPs were probably biotransformed by plants. The edge energy positions of NP-treated samples were at the same position as Zn(NO3)2, which indicated that Zn in all plant species was as Zn(II).
Dissertations / Theses on the topic "ZnO NPs"
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Singh, Jai, O. N. Srivastava, R. S. Tiwari, and P. Kumar. "Structural and optical investigations of low temperature solution based synthesized ZnO and Ag admix ZnO nanoparticles (NPs)." Thesis, Видавництво СумДУ, 2011. http://essuir.sumdu.edu.ua/handle/123456789/20574.
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Rubio-Garcia, Javier. "Strategies to yield water dispersible ZnO NPs synthesized by an organometallic approach." Toulouse 3, 2010. http://thesesups.ups-tlse.fr/891/.
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Le nombre d'études sur la synthèse et l'application de matériaux semi-conducteurs a augmente au cours des dernières années dû à la dépendance de propriétés physiques et chimiques de ces matériaux avec la taille. Plusieurs applications ont émergées, notamment dans les domaines de la biomédecine, les cellules solaires ou de l'électronique. Parmi les matériaux semi-conducteurs connus, ZnO nanométrique est un bon candidat pour ces applications car il est relativement peu coûteux et respectueux avec l'environnement. Des méthodes physiques et chimiques permettant la production de nanostructures de ZnO ont été décrites dans la littérature. Certaines applications des nanoparticules de ZnO nécessitent des solutions colloïdales et de ce point de vue, les méthodes chimiques sont avantageuses. Dans notre groupe de recherche, une méthode chimique basée sur la décomposition de précurseurs organométalliques en présence d'un agent de stabilisation a été développée. Cependant, cette stratégie ne permet la production de nanoparticules de ZnO uniquement solubles dans les solvants apolaires. Les applications en cosmétiques ou en biomédecine ne sont alors pas possibles. Le but de cette thèse est la modification de la synthèse organométallique pour atteindre des nanoparticules de ZnO solubles dans l'eau: soit par modification des particules synthétisées ou par modifications de la procédure synthèse initialeThere is an ever increasing interest in the synthesis and application of semiconducting materials due to their size-dependent physical and chemical properties (nanometric range). Multiple applications have radically emerged over the last few years including in the areas of biomedicine, solar cells or electronics. Among the semiconducting materials, nanosized ZnO is a good candidate for these applications as it is a relatively inexpensive and environmentally friendly material. Physical and chemical methods allow for the production of ZnO nanostructures. For some applications ZnO nanoparticles (NPs) are required as colloidal solutions and chemical methods are advantageous. In our research group, a chemical method based on the decomposition of organometallic precursors in the presence of a stabilizing agent has been developed. Good control with respect to the average size and the size distribution is achieved. However, this strategy presents as a main drawback the production of ZnO NPs that are only dispersible in non polar solvents. Application for cosmetics or in the field of biomedicine is impeded as a result. The motivation for this Thesis has been to bring about synthetic modification of the organometallic strategy in order to achieve ZnO NPs dispersible in water: either modification of the as-synthesized particles or changes to the synthetic procedure are mandatory
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Villafuerte, Diaz José Guillermo. "Nanofils de ZnO résistifs synthétisés par dépôt en bain chimique pour capteurs piézoélectriques flexibles." Thesis, Université Grenoble Alpes, 2022. http://www.theses.fr/2022GRALI056.
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Les NWs de ZnO hautement résistifs sont destinés à être utilisés comme capteurs de pression dans des substrats flexibles. Pour cela, il était important de développer le rôle important des défauts liés à l'hydrogène et à l'azote dans les NWs de ZnO cultivés par CBD, comme cela a été largement étudié dans cette thèse. Le chapitre 1 détaille l'état de l'art de la présente thèse et le chapitre 2 détaille les procédures expérimentales utilisées pour développer les différentes études de cette thèse. Dans le chapitre 3, la conduction électrique de type métallique des NWs de ZnO cultivés spontanément a été attribuée à une forte densité de porteurs de charge libre due aux défauts liés à l'hydrogène (c'est-à-dire le HBC et le VZn-3H agissant comme des donneurs superficiels). Ensuite, le chapitre 4 démontre la capacité d'ingénierie des NWs de ZnO par recuit thermique sous une atmosphère d'oxygène, montrant que la densité des défauts liés à l'hydrogène diminue à ~300 °C, et que l'activation thermique de VZn-NO-H (agissant comme accepteur profond) à ~450 °C favorise une compensation importante. De plus, l'incorporation intentionnelle d'atomes dopants de Sb dans les NWs de ZnO apporte une nouvelle approche en réalisant les croissances dans les régions à faible et à fort pH, comme cela a été fait dans le chapitre 5. Ainsi, le chapitre 6 élucide la modulation complexe entre les défauts liés à l'hydrogène, à l'azote et à l'antimoine dans les différentes conditions de croissance et de recuit. En particulier, le nouveau recuit en deux étapes à 300 °C pendant 4 heures et une heure consécutive à 450 °C illustre la possibilité de diffuser exogène les donneurs d'hydrogène et d'activer thermiquement les défauts liés au VZn-NO-H et au Sb. Enfin, le chapitre 7 montre l'incorporation de ces NWs de ZnO hautement résistifs comme capteurs piézoélectriques flexiblesHighly resistive ZnO NWs are intended for their application as pressure sensors in flexible substrates. To achieve this, it was important to develop the important role of hydrogen- and nitrogen-related defects in ZnO NWs grown by CBD, as it has been extensively studied in this thesis. Chapter 1 details the state-of-the-art of the present thesis and Chapter 2 details the experimental procedures used to develop the different studies of this thesis. In Chapter 3, the metal-like electrical conduction of spontaneously grown ZnO NWs was attributed to a high density of free charge carriers due to hydrogen-related defects (i.e., HBC and VZn-3H acting as shallow donors). Then, Chapter 4 demonstrates the capacity to engineer the ZnO NWs by thermal annealing under an oxygen atmosphere, showing that the density of hydrogen-related defects would decrease at ~300 °C, and the thermal activation of VZn-NO-H (acting as deep acceptor) at ~450 °C would promote an important compensation. Furthermore, the intentional incorporation of Sb dopant atoms in the ZnO NWs bring a novel approach by performing the growths in the low- and high-pH regions, as performed in Chapter 5. Hence, Chapter 6 elucidates the complex modulation between the hydrogen-, nitrogen- and antimony-related defects at the different growth conditions and the different annealing conditions. Particularly, the novel two-step annealing at 300 °C for 4 h and a consecutive 1 h at 450 °C will illustrate the possibility to exo diffuse the hydrogen-donors and thermally activate the VZn-NO-H and Sb-related defects. Finally, Chapter 7 shows the incorporation of these highly resistive ZnO NWs as flexible piezoelectric sensors
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Magnan, Romain. "Oxyde transparent conducteur de ZnO : V à partir d'une cible de nanoparticules : de l’ablation par laser pulsé à un procédé de décharge à barrière diélectrique double fréquence à pression atmosphérique Transparent and conductive vanadium doped zinc oxide thin films by pulsed laser deposition from different targets Atmospheric pressure dual RF-LF frequency discharge: Influence of LF voltage amplitude on the RF discharge behavior Atmospheric pressure dual RF-LF frequency discharge: transition from α to α-γ-mode." Thesis, Perpignan, 2020. http://www.theses.fr/2020PERP0008.
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Cette thèse en cotutelle entre la France et le Canada a pour objectif de développer une méthode innovante d’élaboration de couches minces nano-composites de ZnO:V, basée sur la mise en vol et le dépôt de nanoparticules (NPs) de ZnO :V par des Décharges à Barrière Diélectrique (DBDs) double fréquence. Cette méthode de dépôt vise à réduire le coût de production par l’utilisation de nanoparticules synthétisées par méthode sol-gel et de DBDs dans une configuration permettant le dépôt de couches minces en continu à pression atmosphérique. Les travaux se sont déroulés en trois phases :- L’étude des OTC obtenus par ablation laser à partir d’une cible de NPs de ZnO:V(1 %at.) et de cibles métalliques de ZnV. La résistivité la plus faible (4 x 10 4 Ω.cm) est observée pour les dépôt faits à 250 °C à partir d’une cible de Zn :V(3 %at.) alors que les meilleures propriétés optiques sont celles d’une couche mince quasi-amorphe obtenue à 20 °C à partir de la cible de NPs de ZnO:V. Ces couches minces présentent une transmission de 40% dans l’UV à 250 nm, 90% dans le visible et 80% dans le PIR à 2500 nm) avec une résistivité de 6 x 10-2 Ω.cm. - La recherche et l’optimisation d’une source plasma DBD pour mettre en vol des NPs de ZnO:V dans une configuration compatible avec le dépôt de couches minces contrôlées. La démarche a consisté à chercher à accroître le flux et l’énergie des ions à la cathode en appliquant, sur une des électrodes, une tension radiofréquence (5 MHz) qui génère une forte densité d’ions (~2 x 1011/cm3) et sur l’autre électrode une tension basse fréquence (50 kHz) afin de transporter les ions vers la cathode. La première étape a été de bien comprendre la physique de la DBD RF-BF en couplant la caractérisation optique de la décharge et la modélisation fluide 1D. Lorsque la tension BF augmente, la décharge initialement RF en régime α bascule en régime α-γ durant 1/5 du cycle BF. Les résultats montrent qu’en régime γ la décharge est auto-entretenue dans la gaine et le flux d’ions à la cathode est multiplié par un facteur 7 alors que leur énergie s’accroit d’un facteur 4. L’étude expérimentale montre que lorsqu’une cible de NPs interagit avec une DBD RF-BF, des NPs sont mises en vol.- La conception et le test d’une configuration de réacteur DBD comprenant 2 zones plasmas successives : la première pour mettre en vol les NPs d’une cible, la deuxième pour déposer les NPs sur un substrat. Cette dernière est basée sur une DBD double fréquence BF-BF obtenue par application d’une tension 50 kHz qui génère des électrons pour charger les NPs et une tension 1 kHz dont on sait qu’elle peut assurer le transport des NPs chargées du volume vers les surfaces. La faisabilité a été montrée par l’observation de NPs sur le substratThis thesis jointly supervised by France and Canada aims to develop an innovative method for the development of thin nanocomposite layers of ZnO: V, based on the sputtering and deposition of ZnO: V nanoparticles (NPs) using Double Frequency Dielectric Barrier Discharges (DBDs). This deposition method aims to reduce the cost of production by using nanoparticles synthesized by the sol-gel method and DBD in a configuration allowing the deposition of thin films continuously at atmospheric pressure. The work took place in three phases:- The study of TCO obtained by pulsed laser deposition from a target of NPs of ZnO: V (1% at.) and metal targets of ZnV. The lowest resistivity (4 x 10-4 Ω.cm) is observed for the deposits made at 250 ° C from a Zn: V target (3% at.) While the best optical properties are those of a quasi-amorphous thin layer obtained at 20 ° C from the NPs target of ZnO: V. These thin films have a transmission of 40% in UV at 250 nm, 90% in the visible and 80% in the PIR at 2500 nm) with a resistivity of 6 x 10-2 Ω.cm.- Research and optimization of a DBD plasma source to sputter ZnO: V NPs in a configuration compatible with the deposition of controlled thin films. The approach consisted in increase the flow and energy of the ions at the cathode by applying, on one of the electrodes, a radiofrequency voltage (5 MHz) which generates a high density of ions (~ 2 x 1011 / cm3) and on the other electrode a low frequency voltage (50 kHz) in order to transport the ions to the cathode. The first step was to understand the physics of the DBD RF-BF by coupling the optical characterization of the discharge and the 1D fluid modeling. When the LF voltage increases, the initially RF discharge in the α regime switches to the α-γ regime for 1/5 of the LF cycle. The results show that in γ regime the discharge is self-sustaining in the sheath and the flow of ions at the cathode is multiplied by a factor of 7 while their energy increases by a factor of 4. The experimental study shows that when an NPs target interacts with an RF-BF DBD, NPs are brought into flight.- The design and testing of a DBD reactor configuration comprising 2 successive plasma zones: the first to launch the NPs of a target, the second to deposit the NPs on a substrate. The latter is based on a double frequency BF-LF DBD obtained by applying a 50 kHz voltage which generates electrons to charge the NPs and a 1 kHz voltage which we know can ensure the transport of charged NPs from the volume to surfaces. The feasibility was shown by the observation of NPs on the substrate
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Nascimento, JoÃo Paulo Costa do. "Estudo dos Efeitos da AdiÃÃo de Zn2+ e de Ãons Terras-Raras nas Propriedades DielÃtricas e de LuminescÃncia da Matriz CerÃmica Lanbo4." Universidade Federal do CearÃ, 2014. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=13113.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorCom o rÃpido crescimento de tecnologias sem fio, a indÃstria de telecomunicaÃÃes tem buscado constantemente materiais que possuam excelentes caracterÃsticas dielÃtricas para ser à base de novos dispositivos. Devido a essa demanda sempre crescente, pesquisas em busca de novos e melhores materiais cerÃmicos tÃm ocupado cada vez mais lugar de destaque no interesse da comunidade cientÃfica mundial. O uso de materiais cerÃmicos em busca de materiais fluorescentes tambÃm vem recebendo destaque, jà que materiais desse tipo apresentam diversas aplicaÃÃes, tais como lasers; diodo emissor de luz (LED); como fonte de luz sensores; estocagem de dados Ãticos e atà mesmo na Ãrea mÃdica. Neste trabalho foram estudados as propriedades da matriz cerÃmica LaNbO4 (LNO) modificada pela adiÃÃo de ZnO e tambÃm pela dopagem com Ãons terras-raras Ãrbio; itÃrbio e tÃlio. As amostras de LNO e dopadas foram obtidas atravÃs do mÃtodo reacional do estado sÃlido utilizando Ãxidos precursores seguido de tratamento tÃrmico, enquanto as amostras com ZnO foram obtidas atravÃs da adiÃÃo de determinada quantidade de massa deste sobre o LNO. Os resultados de difraÃÃo de Raios-X e espectroscopia Raman confirmaram a obtenÃÃo da fase cerÃmica LNO e os valores das propriedades dielÃtricas desse material foram prÃximos da literatura. A simulaÃÃo numÃrica realizada para o LNO apresentou bom valor de ganho e alta eficiÃncia, mostrando que esse material pode atuar como DRA. Quanto à adiÃÃo de ZnO, a difraÃÃo de Raios-X mostrou que praticamente nÃo houve mudanÃas no padrÃo de difraÃÃo da fase LNO. Jà com relaÃÃo Ãs propriedades dielÃtricas foi observado que essa adiÃÃo causou aumento nos valores de permissividade e tangente de perda de forma nÃo linear com o aumento da concentraÃÃo de zinco. Nos sistemas contendo Ãons terras-raras a difraÃÃo Raios-X e espectroscopia Raman indicaram que os Ãons dopantes entraram na estrutura cristalina da fase LNO. Na fluorescÃncia foram observadas bandas na regiÃo do verde e vermelho para as amostras com Er3+ e Yb3+, referentes Ãs transiÃÃes dos orbitais 4f do Er3+. Enquanto que para o sistema com Er3+, Yb3+ e Tm3+ foram observadas bandas nas regiÃes do ultra-violeta; azul; verde; vermelho e infravermelho originadas das transiÃÃes dos orbitais 4f do Er3+ e 4f do Tm3+.
With the rapid growth of wireless technologies, the telecommunications industry has constantly searching materials having excellent dielectric characteristics to be based on new devices. Due to this ever increasing demand, research for new and improved ceramic materials have occupied prominent place in the interest of the scientific community worldwide. The use of ceramic materials in search of fluorescent materials also has received attention, since such materials have several applications, such as lasers; light emitting diode (LED); as a source of light sensors; optical data storage and even in the medical field. In this work were studied the properties of LaNbO4 (LNO) matrix modified by adding of ZnO and also by doping with rare-earth ions erbium; ytterbium and thulium. The pure and doped LaNO4 samples were obtained by solid state reaction method using oxide precursor followed by heat treatment, while samples with ZnO was obtained by adding of determined quantity of latter on the LNO. The results of x-ray diffraction and Raman spectroscopy confirmed the formation of the ceramic phase LNO and the values of the dielectric properties obtained of this material were close to the values of the literature. The numerical simulation realized for LNO presented good gain value and a high efficiency, showing that this material can act as a DRA. About the addition of zinc, the x-ray diffraction showed that practically not occured significant changes in the diffraction pattern of LNO phase, being that regarding the dielectric properties was observed that the addition caused increase in the values of the permittivity and loss tangent nonlinearly with the increasing of the concentration of zinc. In the systems containing rare-earth ions the X-ray diffraction and Raman spectroscopy indicated that the dopant ions entered on the crystalline lattice of LNO phase. In the fluorescence were observed bands in the green and red region for the system with Er3+ and Yb3+ , concerning the transitions between the 4f orbitals of Er3+ . While for the system with Er3+ , Yb3+ and Tm3+ were observed bands in the ultraviolet region; blue; green; red and infrared originated of transitions that occur in the 4f orbitals of Er3 + and in the 4f orbitals of Tm3+.
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Gonçalves, Rafael Silva. "Efeitos da interface e da dopagem nas propriedades estruturais, óticas e elétricas de filmes finos de ZnO." Universidade Federal de Sergipe, 2016. https://ri.ufs.br/handle/riufs/5381.
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Conselho Nacional de Pesquisa e Desenvolvimento Científico e Tecnológico - CNPqIn this work, we described the structural, morphological, optical and electrical properties of the ZnO thin films undoped and chromium (Cr), copper (Cu), aluminium (Al) doped deposited using magnetron sputtering and co-sputtering method on glasses, Cr and niobium (Nb) substrates. For characterization of the samples were used the X-ray diffraction (XRD), X-ray reflectometry (XRR), UV-Vis spectroscopy in the visible region techniques and IxV plots. This work was divided in two parts, in the study I, ZnO films were grown on glasses substrates and the influence of the substrate temperature, RF power and films thickness at the structural, morphological and optical properties was studied. The results showed that all films grown exhibit characteristic peaks of hexagonal wurtzite phase with axis-c preferential orientation, the films roughness was very influenced by thickness and temperature and the gap energy varied with the films thickness. In the study II, thin films undoped and doped were grown at 300ºC on different substrates and the influence of kind of substrate, dopants, dopant concentration on the structural, morphological, optical and electrical properties was studied. Generally, all samples deposited on Cr substrates exhibit resistance lower than the samples deposited on Nb substrates. For some samples, an unusual behavior was observed at the moment of electrical measurements, after any voltage, different for each sample, the current fell abruptly.
Neste trabalho, descrevemos as propriedades estruturais, morfológicas, ópticas e elétricas de filmes finos de ZnO puros e dopados com cromo (Cr), cobre (Cu) e alumínio (Al) depositados por sputtering e co-sputtering em substratos de vidro, Cr e nióbio (Nb). Foram utilizadas as técnicas de difração de raios X (DRX), reflectometria de raios X (XRR), espectroscopia óptica na região do UV-Vis e curvas de IxV para caracterização das amostras. O trabalho foi dividido em duas etapas, na primeira etapa foram estudados os efeitos da espessura, da temperatura do substrato e da potência RF nas propriedades estruturais, morfológicas e ópticas dos filmes de ZnO crescidos sobre substrato de vidro. Os resultados mostraram que todos os filmes produzidos apresentam picos característicos da fase hexagonal wurtzita com orientação preferencial ao longo do eixo-c, a rugosidade dos filmes foi bastante influenciada pela espessura e temperatura e a energia de gap variou com a espessura dos filmes. Na segunda etapa, filmes finos puros e dopados foram depositados a 300ºC em diferentes substratos. Nesta etapa foram investigados a influência do tipo de substrato e da concentração dos dopantes nas propriedades estruturais, morfológicas, ópticas e elétricas. Os resultados mostraram que a cristalinidade dos filmes de ZnO foi fortemente influenciada pela rugosidade do substrato. De modo geral, todas as amostras depositadas sob substratos de Cr apresentaram resistência menores do que as amostras depositadas sob Nb. Para algumas amostras, um comportamento não usual foi observado no momento das medidas elétricas onde após uma determinada tensão, diferente para cada amostra, a corrente caía abruptamente.
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Silva, Douglas Carlos de Sousa. "Síntese e caracterização de heteroestruturas de Ag2MoO4 e ZnO e investigação da sinergia nas propriedades fotocatalíticas e fotoluminescentes." Universidade Federal de Goiás, 2017. http://repositorio.bc.ufg.br/tede/handle/tede/7260.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Nanostructured materials, such as: Ag2MoO4 and ZnO are of great importance because they have unique characteristics and properties, and can be applied in sensors, catalysis, photoluminescence, among other applications. In this work, the Ag2MoO4 and ZnO powders were synthesized separately and in the form of heterostructures, by two different routes, coprecipitation (CP), at room temperature and coprecipitation with subsequent microwave assisted hydrothermal treatment (CPMAHT), at 130 ° C for 30 min, with a heating rate of 10 ° C / min. The heterostructures composed of both materials, Ag2MoO4 and ZnO present in molar proportions ranging from 0.25-2.00%, were synthesized by coprecipitation with subsequent sonochemical processing (CPSP). The Ag2MoO4 samples were obtained with pure cubic phase of spinel type with crystallite size of 143 nm for the sample obtained by CP and 90 nm for the sample obtained by CPTHAM. For the ZnO the hexagonal phase of the wurtzite type, with crystallite sizes of 19 and 49 nm, was obtained for the samples obtained by CP and CPTHAM, respectively. The phases of both Ag2MoO4 and ZnO were observed for the heterostructures obtained by CPSP. The structural and morphological characterization of the obtained materials was performed using X-ray diffraction (XRD) techniques and scanning electron microscopy (SEM). The diffusion reflectance UV-Vis spectroscopy (DRS) was performed to determine the band gap values of the materials. The photoluminescent property was investigated by means of the photoluminescence spectroscopy (PHS) technique, with an improvement in the photoluminescent property of broadband for all the obtained heterostructures. It was also observed that the synergism of the Ag2MoO4 and ZnO materials in the heterostructures resulted in an improvement in the photocatalytic property, leading to a 90% discoloration of the rhodamine B dye in 90 min for the photocatalysis using the Ag2MoO4: 2 ZnO heterostructure.
Materiais nanoestruturados, tais como: o Ag2MoO4 e o ZnO são de grande importância por apresentarem características e propriedades únicas, podendo ser aplicados em sensores, catálise, fotoluminescência, dentre outras aplicações. Neste trabalho, os pós de Ag2MoO4 e ZnO foram sintetizados na sua forma pura por duas rotas diferentes, coprecipitação (CP) a temperatura ambiente e coprecipitação com posterior tratamento hidrotérmico assistido por microondas (CPTHAM), a 130 °C durante 30 min, com taxa de aquecimento de 10 °C/min. Heteroestruturas compostas por ambos os materiais, Ag2MoO4 e ZnO foram obtidas com proporções de 0,25; 0,50; 1 e 2 mols de ZnO para 1 mol de Ag2MoO4. Estas heteroestruturas foram sintetizadas por coprecipitação com posterior processamento sonoquímico (CPPS). As amostras de Ag2MoO4 foram obtidas com fase cúbica pura do tipo espinélio com tamanho de cristalito de 143 nm para a amostra obtida por CP e 90 nm para a amostra obtida por CPTHAM. Para o ZnO foi obtida a fase hexagonal do tipo wurtzita, com tamanhos de cristalito de 19 e 49 nm, para as amostras obtidas por CP e CPTHAM, respectivamente. Foram observadas ambas as fases, tanto do Ag2MoO4 quanto do ZnO para as heteroestruturas obtidas por CPPS. A caracterização estrutural e morfológica dos materiais obtidos foi realizada utilizando das técnicas de difração de raios X (DRX) e microscopia eletrônica de varredura (MEV). A espectroscopia de UV-Vis por reflectância difusa (ERD) foi realizada para determinação dos valores de “band gap” dos materiais. A propriedade fotoluminescente foi investigada por meio da técnica de espectroscopia de fotoluminescência (EFL), sendo observado uma melhora na propriedade fotoluminescente de banda larga para todas as heteroestruturas obtidas. Foi observado também que a sinergia dos materiais Ag2MoO4 e ZnO nas heteroestruturas resultou em uma melhora na propriedade fotocatalítica, levando a uma descoloração do corante rodamina B de 90 % em 90 min para a fotocatálise usando a heteroestrutura Ag2MoO4: 2 ZnO.
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Merissi, Thiago Lima. "A conservação da biodiversidade nos discursos expositivos do Zoo de Barcelona." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/81/81133/tde-24062016-160738/.
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A Educação para a Conservação é um campo de pesquisa que se dedica ao estudo das reflexões éticas e das atitudes humanas direcionadas para com o respeito que se deve ter com o ambiente, principalmente pelo estabelecimento de ações conservacionistas pautadas em interações educativas. Os Zoos, de modo geral, estão inseridos nessa perspectiva, uma vez que se apresentam como instituições de cunho educativo voltadas para a conservação da biodiversidade. No entanto, o discurso expositivo apresentado por esses aparatos culturais no Brasil, muitas vezes, não contempla tais elementos em suas exposições. Por este motivo, buscou-se a análise de exposições zoológicas também no exterior, que contemplassem discursos sobre a conservação da biodiversidade em suas exposições, tendo sido escolhida a exposição do Zoo de Barcelona, Espanha, para a realização desta investigação. A pesquisa teve por objetivos compreender como a conservação da biodiversidade é abordada na exposição deste zoológico catalão, com base na formulação de saberes de referência constituídos a partir de diferentes áreas: os Movimentos Ambientalistas, a Filosofia da Conservação e as Éticas Ambientais. Igualmente, buscou-se compreender como o discurso expositivo sobre conservação encontra-se apresentado nos aparatos expográficos distribuídos ao longo da exposição, bem como em livros e documentos. Compreendendo a investigação como um Estudo de Caso, foram acessados documentos institucionais de acesso público encontrados no site da instituição e textos presentes nos painéis expositivos. As análises foram realizadas com base no referencial teórico da Transposição Didática/Museográfica, que permite o estudo da exposição por ao menos três lógicas: a lógica do discurso; a lógica do espaço; e a lógica do gesto. Além disso, o mesmo referencial prevê o estabelecimento de um saber de referência ou saber sábio pautado no conhecimento epistemológico sobre a conservação da biodiversidade e, nesta pesquisa, no discurso de pesquisadores da área, que foram entrevistados sobre este assunto. Este saber de referência ou saber sábio possibilitou a criação de um conjunto de categorias de análise que pautou a análise do discurso expositivo apresentado pelo Zoo de Barcelona. As categorias criadas foram classificadas em duas dimensões: a dos Valores e a das Ações. Duas categorias, a Antropocêntrica e a Não antropocêntrica constituíram a Dimensão dos Valores e quatro categorias, a Desenvolvimentista, a Sustentabilista, a Sócio-humanística e a Técnico-científica constituíram a Dimensão das Ações. Os resultados apontaram que o discurso expositivo é composto predominantemente por informações Técnico-científicas e Sustentabilistas, ambas as categorias contextualizadas por uma visão não antropocêntrica de valorização da natureza. A forma como o discurso expositivo encontra-se apresentado na parte textual da exposição corrobora a linha conceitual de assuntos abordados nos grandes eventos globais promovidos pela ONU ao longo dos últimos 40 anos, sobre a conservação do meio ambiente. Categorias como a Sócio-humanística, a Antropocêntrica e a Dimensão dos Valores foram pouco abordadas. A categoria Desenvolvimentista não foi encontrada na exposição. Pelas evidências levantadas durante a análise dos dados pode-se concluir que o Zoo de Barcelona apresenta um discurso expositivo conservacionista e que há elementos suficientes na exposição para se apontar o desenvolvimento de uma Educação para a Conservação.Education for Conservation is a research field dedicated to the study of ethical reflections and human attitudes directed towards the respect which must have it for the environment, especially the establishment of conservation actions based on educational interactions. Zoos, in general, are entered in this perspective, as it is presented as an educational institutions type directed to the conservation of biodiversity. Though, the expositive speech presented by this cultural mechanism in Brazil often does not include this kind of elements in its exhibitions. Therefore, it sought the zoo expositions analysis also abroad, that addressed discourses on biodiversity conservation in their expositions, which was chosen the Zoo of Barcelona\' exposition, Spain, to perform this research. The research aimed to understand how biodiversity conservation is addressed in this exposition Catalan zoo, based on the formulation made up from different areas of knowledge reference: the Environmental Movement, the Conservation Philosophy and Environmental Ethics. Also, it sought to understand how the expositive speech on conservation is presented in expographic devices distributed throughout the exhibition, as well as books and documents. Understanding the investigation as a Study\'s Case, it was accessed institutional documents of publicly accessible found on other website and present texts in the exhibition panels. The analysis were performed based on the theoretic framework of Didactic Transposition/ Museographic, allowing the expositive study for at least three logics: the logic of speech; the logic of the space; and the management logic. Moreover, the same reference provides for the establishment of a knowledge reference or wise knowledge, guided the epistemological knowledge about the conservation of biodiversity and, in this study, the area\'s researchers, who were interviewed on this subject. This reference knowledge or wise knowledge allowed creating a set of categories of analysis that guided the analysis of expositive speech presented by the Zoo of Barcelona. The created categories were classified in two dimensions: Values and Actions. Two categories, Anthropocentric and non-anthropocentric composed the Values Dimension and four categories, Developmental, the Sustainable, the Socio-humanistic and technical-scientific formed the Actions Dimension. The results showed that the expositive speech consists mainly of Technical- scientific and Sustainable information, both contextualized categories by a non-anthropocentric vision of nature appreciation. The way the expositive discourse is presented in the textual part of the exhibition confirms the conceptual range of issues addressed in major global events organized by the ONU over the past 40 years on the conservation of the environment. Categories such as socio-humanistic, the Anthropocentric and Dimension Values were rarely addressed. The Developmental category was not found in the exposition. The evidence gathered during the data analysis can be concluded that the Zoo of Barcelona presents a conservation exhibition speech and that there are sufficient elements in the exhibition to point out the development of an Education for Conservation.
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Gomes, Mônica Borges. "Efeito magnetocalórico nos compostos Gd(Zn1-xCdx) e Gd(Pd1-xRhx)." Universidade do Estado do Rio de Janeiro, 2006. http://www.bdtd.uerj.br/tde_busca/arquivo.php?codArquivo=684.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorNesta dissertação, calculamos as propriedades magnéticas e termodinâmicas e o efeito magnetocalórico em compostos do tipo Gd(A1-xBBx), onde A e B são elementos não magnéticos. Para tal finalidade, usamos um modelo hamiltoniano de spins localizados, incluindo o acoplamento com um campo magnético externo. A interação spin-spin é tratada na aproximação de campo molecular. O parâmetro de interação de troca indireta entre os spins localizados é calculado como uma função da concentração de impurezas. Para esse fim, usamos um modelo no qual a desordem química é tratada na aproximação do potencial coerente. Aplicamos o modelo para estudar o efeito magnetocalórico nos compostos Gd(Zn1-x Cdx) e Gd (Pd1-xRHx). As variações adiabáticas da temperatura e as variações isotérmicas da entropia calculadas para variações de campo magnético estão em bom acordo com os dados experimentais.
In this work we calculated the magnetic and thermodynamic properties as well as the magnetocaloric effect in the compounds Gd(A1−xBBx), where A and B are non-magnetic impurities. For this purpose, we use a model Hamiltonian of interacting spin including the coupling with an external magnetic field. The spin-spin interaction is treated in the molecular field approximation. The indirect exchange interaction parameter between localized spins is calculated as a function of the impurity concentration. To this end we use a model in which the disorder is treated in the coherent potential approximation. We apply the model to study the magnetocaloric effect in the compounds Gd(Zn1−xCdx) and Gd(Pd1−xRhx). The calculated adiabatic temperature changes and isothermal entropy changes upon magnetic field variations are in good agreement with the available experimental data.
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Silva, Paulo Maria de Oliveira e. "Estudo dos efeitos da adiÃÃo de ZnO e Nb2O5 nas propriedades dielÃtricas da matriz cerÃmicas BaBi4Ti4O15 (BBT) e suas aplicaÃÃes em antenas." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10945.
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nÃo hÃCom o rÃpido crescimento das indÃstrias de telecomunicaÃÃes criou-se uma forte necessidade por materiais cerÃmicos para aplicaÃÃes em micro-ondas. Devendo estes materiais apresentar alta permissividade dielÃtrica (εr), elevado fator de qualidade (Q), boa estabilidade tÃrmica (τf Â10 ppm/ÂC) e baixo custo. Com a invenÃÃo de telefones celulares portÃteis, o campo da comunicaÃÃo sem fio passou por um crescimento inovador nas Ãltimas dÃcadas. O sucesso da terceira geraÃÃo (3G) dos serviÃos de comunicaÃÃo de telefonia celular, motiva o desenvolvimento de banda larga de quarta geraÃÃo (4G) de telefones celulares e outros produtos e serviÃos sem fio, como por exemplo, o Bluetooth. Este trabalho consiste no desenvolvimento e caracterizaÃÃo da cerÃmica de titanato de bÃrio-bismuto (BaBi4Ti4O15) com adiÃÃo de Ãxido de niÃbio (Nb2O5) ou Ãxido de zinco (ZnO), visando a diminuiÃÃo da temperatura de sinterizaÃÃo e possivelmente melhorar a densificaÃÃo, e posteriormente, verificar as modificaÃÃes ocorridas nas propriedades do material, como por exemplo, o coeficiente de temperatura da frequÃncia ressonante (τf). As sÃries cerÃmicas foram produzidas usando a reaÃÃo no estado sÃlido, com o uso de moagem mecÃnica de alta energia e tratamento tÃrmico. A caracterizaÃÃo estrutural foi realizada com base na Microscopia EletrÃnica de Varredura (MEV) e Picnometria. As densidades relativas das amostras adicionadas com (ZnO) a de maior concentraÃÃo teve valor de 77% enquanto que o BBT puro o valor foi de 56%. As densidades relativas das amostras adicionadas com (Nb2O5) a de maior concentraÃÃo teve valor de 61% em relaÃÃo ao BBT puro. Foram realizados experimentos para avaliaÃÃo do comportamento elÃtrico e dielÃtrico das amostras, na faixa de Micro-ondas e RadiofrequÃncia (temperatura ambiente e com variaÃÃo de temperatura). Por fim, o material foi testado como uma DRA, e posteriormente os resultados obtidos foram simulados atravÃs do programa HFSS. As caracterÃsticas da DRA da cerÃmica pura sÃo 1,12dBi de ganho e 32,51% de eficiÃncia. A DRA que foi adicionada com 2% de (ZnO) apresentou ganho de 1,16dBi com 33,96% de eficiÃncia, enquanto a que foi adicionada com 5% de (Nb2O5) apresentou 1,41dBi de ganho com 42,21% de eficiÃncia.
With the rapid growth of the telecommunications industry created a strong need for ceramic materials for applications in microwave. These materials should exhibit high dielectric permittivity (εr), high quality factor (Q), good thermal stability (τf Â10 ppm/ÂC) and low cost. With the invention of mobile phones, the field of wireless communication has undergone a revolutionary growth in recent decades. The success of the third generation (3G) services in mobile communication, motivates the development of broadband fourth generation (4G) of mobile phones and other wireless products and services, such as Bluetooth. Nowadays it is well known the use of tablets, which are increasingly gaining market and encouraging the development of new technologies to improve the flow of information. This work involves the development and characterization of the barium bismuth titanate ceramic, (BaBi4Ti4O15) with addition of niobium oxide (Nb2O5) or zinc oxide (ZnO) in order to decrease the sintering temperature and possibly improve the densification and subsequently check the modifications on material properties, such as the temperature coefficient of resonant frequency (τf). The series ceramics were produced using the solid state reaction with the use of high energy mechanical milling and heat treatment. The structural characterization was performed based on Scanning Electron Microscopy (SEM) and Measurement by Pycnometer. The relative densities of the samples with added (ZnO) had the highest concentration value of 77% pure BBT while the value was 56%. The relative densities of the samples spiked with (Nb2O5) had the highest concentration value of 61% compared to pure BBT. Experiments were conducted to evaluate the electrical and dielectric behavior of the samples in the range of Microwave and Radio Frequency (temperature and temperature variation). Finally, the material was tested as a DRA, and then the results were simulated using the HFSS program. The characteristics of the pure ceramic DRA are 1,12dBi gain and 32,51% efficiency. The DRA added with 2% (ZnO ) showed 1.16dBi gain with 33,96% efficiency , while the one that was added with 5% (Nb2O5) showed gain of 1.41dBi with 42,21% efficiency.
Books on the topic "ZnO NPs"
1
Isabel, Sánchez Ana, ed. Nos compramos un zoo. Mexico: Planeta, 2011.
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2
Ying xiang bei hou 1991-2005: Luke. Danei dian ying shou ji = Au dos de nos images (1991-2005) : suivi de Le Fils, L'Enfant et Le Silence de Lorna. Shanghai: Hua dong shi fan da xue chu ban she, 2015.
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Dimitrov, Nikola. Izkhod bozhiĭ koĭ povi͡a︡rva da se spasi: Blazheno e onova plame, na koeto Bog e Gospodʹ : brati͡a︡ i sestry, iskate li da znaete kakvo shte premine nad Bŭlgarii͡a︡ do 2000ta godina i posle i kak da se izbavim ot vsi͡a︡ko zlo, koeto shte nastane po sveta i u nas? : prochetete tazi kniga! 2nd ed. Bŭlgarii͡a︡: N. Dimitrov, 1994.
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4
Nos compramos un zoo. Planeta, 2011.
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5
Harcourt, Houghton Mifflin. Abrams NFS Infact: Leveled Reader Robot Zoo. Houghton Mifflin Harcourt Publishing Company, 2019.
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Amery, Heather. What's Happening? at the Seaside on the Farm at the Zoo Usb/Nfs. Usborne Publishing Ltd, 1997.
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Ramos-Miranda, Julia, M. A. Cabrera Vázquez, Silvia Salas, J. A. López-Rocha,, D. Flores-Hernández,, E. Torres-Irineo, I. Velázquez-Abunader, and M. A. Sosa Ávila. Artisanal Fishing in the Yucatan Peninsula. A Brief Approach to Fisheries. Resources, Capture and State of Exploitation. EPOMEX-UAC, 2021. http://dx.doi.org/10.26359/376639.042021.
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La presnete obra, es el resultado de uno de los com- ponentes de un proyecto multidisciplinario e inte- rinstitucional titulado “Caracterización de la Pesca Arte- sanal en la Península de Yucatán: Identificando Unidades de Manejo”, financiado por el conacyt (Fondo sep-cona- cyt-Clave 252215), el cual nos permitió acércanos a la pesca artesanal desde varios ángulos considerando los recursos, los usuarios, y sus problemáticas. El trabajo en equipo con investigadores de varias disci- plinas y estudiantes de posgrado y licenciatura del cinves- tav-ipn Unidad Mérida, umdi Sisal-unam y del Instituto epomex-uac, y múltiples estudiantes de Servicio Social y Prácticas Profesionales, rindió frutos. Este es un esfuer- zo de tres años de trabajo, y si bien tratamos de integrar la mayor información disponible a la mano, en sistemas dinámicos como la pesca, queda aún mucho por conocer, entender y problemáticas por abordar. Esperamos que esta obra contribuya a aumentar el co- nocimiento de las pesquerías artesanales en la península de Yucatán, y también que sirva para atraer la vista hacia estas importantes pesquerías que requieren cada vez más atención y nuevos enfoques de evaluación y de manejo.
Book chapters on the topic "ZnO NPs"
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Mokobia, Kate E., Ikhazuagbe H. Ifijen, and Esther U. Ikhuoria. "ZnO-NPs-Coated Implants with Osteogenic Properties for Enhanced Osseointegration." In The Minerals, Metals & Materials Series, 288–300. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-22524-6_27.
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Isa, Eleen Dayana Mohamed, Kamyar Shameli, Nurfatehah Wahyuny Che Jusoh, Roshasnorlyza Hazan, and Nor Azwadi Che Sidik. "Effect of Pullulan Amount on ZnO NPs Via Sol–Gel Technique." In Technological Advancement in Mechanical and Automotive Engineering, 391–98. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-1457-7_32.
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Meshram, S. P., P. D. Jolhe, S. D. Shingte, B. A. Bhanvase, and S. H. Sonawane. "Sonochemical Synthesis of Mg-Doped Zno NPS For Efficient Sunlight Driven Photocatalysis." In Novel Water Treatment and Separation Methods, 47–60. Toronto ; Waretown, NJ : Apple Academic Press, 2017. | "Outcome of national conference REACT- 16, organized by the Laxminarayan Institute of Technology, Nagpur, Maharashtr , India, in 2016"--Introduction. || Includes bibliographical references and index.: Apple Academic Press, 2017. http://dx.doi.org/10.1201/9781315225395-4.
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Rajabairavi, Neethipathi, Chellappan Soundar Raju, Chandrasekaran Karthikeyan, Kandhan Varutharaju, Shanmugam Nethaji, Abdulrahman Syedahamed Haja Hameed, and Appakan Shajahan. "Biosynthesis of Novel Zinc Oxide Nanoparticles (ZnO NPs) Using Endophytic Bacteria Sphingobacterium thalpophilum." In Springer Proceedings in Physics, 245–54. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-44890-9_23.
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Srivastav, Anurag Kumar, Supriya Karpathak, Jyoti Prakash, and Mahadeo Kumar. "Mechanism and Method of Zinc Oxide Nanoparticles (ZnO NPs) Induced Toxicity in Biological Systems." In Integrative Approaches to Biotechnology, 135–51. Boca Raton: CRC Press, 2023. http://dx.doi.org/10.1201/9781003324706-11.
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Li, Likun, Junfu Chen, Jiann-Yang Hwang, JiXiong Liu, Yong Zhou, and Lijun Lu. "Photocatalytic H2Production Under Visible Light Irradiation on Novel Heterostructure NiS/ZnS Nanosheet Photocatalyst." In Characterization of Minerals, Metals, and Materials 2015, 777–84. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2015. http://dx.doi.org/10.1002/9781119093404.ch98.
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Li, Likun, Junfu Chen, Jiann-Yang Hwang, JiXiong Liu, Yong Zhou, and Lijun Lu. "Photocatalytic H2 Production under Visible Light Irradiation on Novel Heterostructure Nis/Zns Nanosheet Photocatalyst." In Characterization of Minerals, Metals, and Materials 2015, 777–84. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-48191-3_98.
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Mukherjee, D. "ZnO for Probes in Diagnostics." In ZnO and Their Hybrid Nano-Structures, 202–33. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902394-7.
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Nanoparticles have revolutionized the field of diagnostics in recent years and ZnO nanoparticles (ZnO-NPs) have been one of the most commonly used ones. These easily synthesizable ZnO-NPs have a multitude of advantages over other metal-based nanoparticles owing to their biocompatibility, easy functionalization through their hydroxyl group-rich surface, and cost-effectiveness among several other benefits. Due to their inherent luminescence and fluorescent-tag functionalizing properties, ZnO-NPs have been useful as a probe in tumour and live cell bioimaging. ZnO-NPs have also been identified as probes in biosensors for the detection of various clinically important biochemical analytes like glucose and cholesterol, pathogens, drug molecules, and antibody-antigen based detection systems. In this chapter, several of the different applications of ZnO as probes in diagnostics will be dealt with in detail. Also, the characteristics of ZnO nanoparticles useful for such applications and the way these devices and techniques are developed will be explained.
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"Zinc Oxide Nanoparticles (ZnO-NPs)." In Encyclopedia of Nanotechnology, 4407. Dordrecht: Springer Netherlands, 2016. http://dx.doi.org/10.1007/978-94-017-9780-1_101182.
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Rana, G. "Advances on ZnO Hetro-Structure as Nanoadsorbant for Heavy Metal Removals." In ZnO and Their Hybrid Nano-Structures, 173–201. Materials Research Forum LLC, 2023. http://dx.doi.org/10.21741/9781644902394-6.
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Industrialization is going at an incredibly fast rate, which is putting more and more heavy metals in the water we drink. Almost all heavy metals are very toxic, and even a small amount of these metals in water can be very bad for humans and for the aquatic ecosystems that live in the water. As a result, the removal of heavy metals from industrial effluents is a big deal. Due to their high surface area to volume ratio, nanoadsorbents have received substantial attention in the past decade for their ability to remove heavy metals from water. Due to its good biocompatibility, low toxicity, negative zeta potential, surface changes during development, and redox reactions resulting from the production of efficient photoinduced electron-hole pairs in ZnO nanoparticles, ZnO is a suitable material for heavy metal remediation. In this chapter, we have discussed the synthesis method of ZnO NPs and their nanocomposites. Also in this chapter, we'll go over how ZnO nanostructures can be used to remove heavy metal ions from water. Various ZnO-based nanostorbents, including virgin ZnO NPs, doped ZnO nanostructures, ZnO nanocomposites, and surface-modified ZnO NPs, are fully examined, with statistical analyses of their maximum adsorption capacity for various heavy metal ions (Cd2+, Hg2+, Pb2+, Cr6+, and Cu2+).
Conference papers on the topic "ZnO NPs"
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Borras, Ana, Manuel Macias-Montero, Angel Barranco, Jose Cotrino, Juan Espinos, and Augustin R. González-Elipe. "Fabrication of heterostructured M@M´Ox Nanorods by low temperature PECVD." In 13th International Conference on Plasma Surface Engineering September 10 - 14, 2012, in Garmisch-Partenkirchen, Germany. Linköping University Electronic Press, 2013. http://dx.doi.org/10.3384/wcc2.47-50.
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In this communication we report on the fabrication of two different heterostructured core@shell 1D materials by low temperature (135 oC) plasma enhanced chemical deposition: Ag@TiO2 and Ag-NPs@ZnO nanorods (NRs). The controlled formation of these heterostructures on processable substrates such as Si wafers, fused silica and ITO is demonstrated. The NRs are studied by SEM, HAADF-STEM, TEM, XRD and in situ XPS in order to fully describe their microstructure and inner structure, eventually proposing a growth mechanism. The first type of nanostructures consists on a silver wire surrounded by a TiO2 shell that grows following the volcano-like mechanism. The Ag-NPs@ZnO nanostructures are formed by supported ZnO nanorods decorated with Ag nanoparticles (NPs). The 3D reconstruction by HAADF-STEM electron tomography reveals that the Ag NPs are distributed along the hollow interior of highly porous ZnO NRs. The aligned Ag-NPs@ZnO-NRs grow by a combination of different factors including geometrical distribution of precursor, plasma sheath and differences in the silver/silver oxide densities. Tuning the deposition angle, Ag-NPs@ZnO-NRs depicting different tilting angles can be homogeneously grown allowing the formation of zig-zag nanostructures. The as prepared surfaces are superhydrophobic with water contact angles higher than 150o. These surfaces turn into superhydrophilic with water contact angles lower than 10º after irradiation under UV light. In the case of the AgNPs@ZnO NRs such modification can be also provoked by irradiation with VIS light. The evolution rate of the wetting angle and its dependence on the light characteristics are related with the nanostructure and the presence of silver embedded within the NRs.
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Rahman, Mohammed W., Rachita Lahri, Michael Wright, Maria Koutsoupidou, Themos Kallos, Maya Thanou, and Panagiotis Kosmas. "Characterisation of ZnO NPs as contrast agents for MWI." In 2017 International Conference on Electromagnetics in Advanced Applications (ICEAA). IEEE, 2017. http://dx.doi.org/10.1109/iceaa.2017.8065433.
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Postica, Vasile, Heather Cavers, Rainer Adelung, Thierry Pauporte, Lee Chow, and Oleg Lupan. "Au-NPs/ZnO Single Nanowire Nanosensors for Health Care Applications." In 2020 International Conference on e-Health and Bioengineering (EHB). IEEE, 2020. http://dx.doi.org/10.1109/ehb50910.2020.9280164.
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Aykaç, Ahmet, and İzel Ok. "Investigations and Concerns about the Fate of Transgenic DNA and Protein in Livestock." In International Students Science Congress. Izmir International Guest Student Association, 2021. http://dx.doi.org/10.52460/issc.2021.046.
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Hydrogels are biocompatible and swollen materials that have been used as a wound dressing for years. Among them, chitosan-based hydrogels have become popular in the wound healing process owing to their low toxic, biocompatible, biodegradable, antibacterial properties. Chitosan (CS) has been used either as a pure form or incorporated with polymers or nanoparticles to increase antimicrobial activity and stability. In this context, zinc oxide nanoparticles (ZnO NPs) have been used to enhance antibacterial activity and mesoporous silica nanoparticles (MSN) have been employed to develop mechanical strength and control of drug release time. In this study, we report the synthesis and fully characterizations of ZnO NPs, MSN and the hydrogel by using dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR). We have also prepared and characterized chitosan-based hydrogels functionalized by MSNs and ZnO NPs.
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Song, Zhi-Ming, Bo Lu, Bin Wang, Qian-Tao Cao, Zhen-Guo Song, and Ying-Lu Hu. "ZnO nanowires ultraviolet detector with high photoresponse based Ag NPs decoration." In 2012 IEEE 11th International Conference on Solid-State and Integrated Circuit Technology (ICSICT). IEEE, 2012. http://dx.doi.org/10.1109/icsict.2012.6467738.
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Pujar, Malatesh S., Shirajahammad M. Hunagund, Raghavendra K. Sali, Aishwarya Nadgir, and Ashok H. Sidarai. "Biological and photocatalytic activities of ZnO NPs over neutral red: Hydrothermal method." In PROF. DINESH VARSHNEY MEMORIAL NATIONAL CONFERENCE ON PHYSICS AND CHEMISTRY OF MATERIALS: NCPCM 2018. Author(s), 2019. http://dx.doi.org/10.1063/1.5098629.
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Dehghani, Marzieh, and Parinaz Ghadam. "Green Synthesis of ZnO-NPs by Juglans regia Green Husk Aqueous Extract." In IOCN 2023. Basel Switzerland: MDPI, 2023. http://dx.doi.org/10.3390/iocn2023-14444.
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Gerasimov, A. S., A. S. Chepusov, V. G. Ilves, O. A. Svetlova, and S. Yu Sokovnin. "Investigation of the photocatalytic activity and radiopacity of nanopowders produced by pulsed electron beam evaporation in vacuum." In 8th International Congress on Energy Fluxes and Radiation Effects. Crossref, 2022. http://dx.doi.org/10.56761/efre2022.n1-o-028201.
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In this work, were investigated the photocatalytic properties and radiopacity of titanium TiO2and zinc oxide Zn-ZnO nanopowders produced by the pulsed electron beam evaporation method in vacuum. Photocatalytic activity was measured based on the rate of decomposition of methyl violet by nanoparticles of various concentrations under the action of UV radiation. Radiopacity was evaluated by comparing the X-ray attenuation coefficients with Na-CMC buffer solution containing NPs test compounds and commercial iodine computer tomography contrast agent Ultravist®. In both cases, the NPs of zinc compounds showed more pronounced properties by accelerating the photodegradation reaction by 1.6 times, relative to the control sample and showing a attenuation factor of 70% of Ultravist®.
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Xie, Huaqing, Wei Yu, Yang Li, and Lifei Chen. "Influencing Factors for Thermal Conductivity Enhancement of Nanofluids." In ASME 2009 Second International Conference on Micro/Nanoscale Heat and Mass Transfer. ASMEDC, 2009. http://dx.doi.org/10.1115/mnhmt2009-18445.
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Nanofluids have attracted increasing interest for more than a decade. A number of studies have demonstrated that nanofluids presented intriguing heat transfer enhancement performances. We produced a series of nanofluids and measured their thermal conductivities. The most used heat transfer fluids including deionized water (DW), ethylene glycol (EG), glycerol, silicone oil, and the binary mixture of DW and EG were used as the base fluids. Various nanoparticles (NPs) including Al2O3 NPs with different sizes, SiC NPs with different shapes, MgO NPs, ZnO NPs, SiO2 NPs, Fe3O4 NPs, TiO2 NPs, diamond NPs (DNPs), and carbon nanotubes (CNTs) with different pretreatments have been used as additives. In the present paper, we summarized our experimental results to elucidate the influencing factors for thermal conductivity enhancement of nanofluids. The thermal transport mechanisms in nanofluids were further discussed and the promising approaches for optimizing the thermal conductivity of nanofluids were proposed.
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Youssef, Ahmed, and Islam EL-Nagar. "Preparation and Characterization of PMMA Nanocomposites Based On Zno-Nps for Antibacterial Packaging Applications." In The 5th World Congress on New Technologies. Avestia Publishing, 2019. http://dx.doi.org/10.11159/icnfa19.105.
Full textReports on the topic "ZnO NPs"
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Turner, R. J. W. Jason Stratiform Zn - Pb - Barite Deposit, Selwyn Basin, Canada [NTS 105 - O - 1]: Geological Setting, Hydrothermal Facies and Genesis. Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 1991. http://dx.doi.org/10.4095/132331.
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Kidder, J. A., M. B. McClenaghan, M I Leybourne, M. W. McCurdy, P. Pelchat, D. Layton-Matthews, C. E. Beckett-Brown, and A. Voinot. Geochemical data for stream and groundwaters around the Casino Cu-Au-Mo porphyry deposit, Yukon (NTS 115 J/10 and 115 J/15). Natural Resources Canada/CMSS/Information Management, 2022. http://dx.doi.org/10.4095/328862.
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This open file reports geochemical data for stream and groundwater samples collected around the Casino porphyry Cu-Au-Mo deposit, one of the largest and highest-grade deposits of its kind in Canada. The calc-alkaline porphyry is hosted in a Late Cretaceous quartz monzonite and associated breccias in the unglaciated region of west central Yukon. Water chemistry around the deposit was investigated because: (i) the deposit has not yet been disturbed by mining; (ii) the deposit was known to have metal-rich waters in local streams; and (iii) the deposit has atypically preserved ore zones. Stream water samples were collected at 22 sites and groundwater samples were collected from eight sites. Surface and groundwaters around the Casino deposit are anomalous with respect to Cd (up to 5.4 µg/L), Co (up to 64 µg/L), Cu (up to 1657 µg/L), Mo (up to 25 µg/L), As (up to 17 µg/L), Re (up to 0.7 µg/L), and Zn (up to 354 µg/L) concentrations. The stable isotopes of O and H of the groundwaters are essentially identical to the surface waters and plot close to the local and global meteoric water lines, indicating that the waters represent modern recharge, consistent with the generally low salinities of all the waters (total dissolved solids range from 98 to 1320 mg/L). Sulfur and Sr isotopes are consistent with proximal waters interacting with the Casino rocks and mineralization; a sulfide-rich bedrock sample from the deposit has delta-34S = -1.2 permille and proximal groundwaters are only slightly heavier (-0.3 to 3.1 permille). These geochemical and isotopic results indicate that surface water geochemistry is a suitable medium for mineral exploration for porphyry-style mineralization in the Yukon, and similar unglaciated regions in Canada. The atypical geochemical signature (Mo, Se, Re, As, Cu) of these types of deposits are typically reflected in the water chemistry and S isotopes provide a more local vectoring tool.
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Hannigan, P. K. A GIS dataset compilation of samples collected for the Targeted Geoscience Initiative project: potential for carbonate-hosted Pb-Zn (MVT) deposits in northern Alberta and southern Northwest Territories (NTS blocks 74, 84, 85, 95). Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2005. http://dx.doi.org/10.4095/221509.
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Hannigan, P. K. A GIS dataset compilation of lead and zinc occurrences for the Targeted Geoscience Initiative project: potential for carbonate-hosted Pb-Zn (MVT) deposits in northern Alberta and southern Northwest Territories (NTS blocks 74, 84, 85). Natural Resources Canada/ESS/Scientific and Technical Publishing Services, 2005. http://dx.doi.org/10.4095/221528.
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