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Neibert, Kevin. "Quantum Dots-interactions at the nano-bio interface." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=122999.
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Nanotechnology is an area of research that lies at the interface of physics, chemistry, engineering and biotechnology. The last decade has seen nanotechnology become a household term, as nano-scale products, known as nanoparticles, have become diverse in nature and form. Despite their immense promise, the widespread application of nanoparticles is currently limited due to their questionable biocompatibility and unclear consequences on cells and other biological components. We have selected fluorescent nanocrystals, called quantum dots (QDs), to investigate the interactions between nanoparticles and the biological environment, due to their superior optical properties. In the present studies, the mechanisms underlying the adaptive cell response to QDs were examined in multiple model cell lines. We observed significant morphological and functional changes at the cellular and subcellular levels following long term exposure to uncapped QDs. We showed that QD-induced toxicity included the production of reactive oxygen and nitrogen species as well as disruption of mitochondrial function. In addition, we found a novel role for transcription factor EB (TFEB), a master regulator of lysosome biogenesis in the successful cellular adaptation process. We showed that modifications to the QD surface can significantly decrease its toxicity, and in some cases, render the QDs non-toxic. Understanding the mechanisms of cellular adaptation to QDs is a first step for the establishment of protocols to evaluate the safety of other nanomaterials. We then investigated the effects of QD surface properties and how they contribute to particle uptake by using QDs with the same core, but with different surface functionalization. We demonstrated that QD surface charge plays an important role in internalization in two different human cell lines. In addition, we provided evidence for the involvement of several overlapping modes of uptake and export from the cell. Finally, we systematically investigated the effects of QD surface properties on particle stability in biological media. We found that serum proteins were differently adsorbed to the particle surface, and this played a key role in determining the primary mode of internalization. Taken together, the results from this work contribute to the development of nano-scale materials in two main ways:1)by presenting in vitro measures as the first step in the evaluation of nanomaterial safety.2)by demonstrating how surface charge and ligand properties drive specific modes of internalization The findings presented herein promote understanding of the intricacies at the nano-bio interface and provide guiding principles for sensible nanoparticle design, with careful consideration for size, shape and surface charge.La nanotechnologie se trouve à l'interface de la physique, de la chimie, de l'ingénierie et de la biotechnologie. Au cours de la dernière décennie, les produits de taille nanométrique, appelées nanoparticules, sont devenus de nature et forme de plus en plus diversifiée menant à un grand essor de la nanotechnologie. Malgré leur immense potentiel, l'application généralisée des nanoparticules est actuellement limitée en raison du manque d'information sur leur biocompatibilité et leurs conséquences néfastes sur les cellules et autres composants biologiques. Nous avons sélectionné des nanocristaux fluorescents de propriétés optiques supérieures, appelés points quantiques (QD), afin d'étudier les interactions entre les nanoparticules et l'environnement biologique. Dans cette étude, les mécanismes sous-jacents de la réponse adaptative des cellules lors de l'exposition à des points quantiques ont été examinés dans plusieurs lignées cellulaires. Nous avons observé des changements morphologiques et fonctionnels importants aux niveaux cellulaire et subcellulaire suite à une exposition de long terme à des points quantiques non-revêtu de coque. Nous avons démontré que la toxicité induite par ces QD implique la production d'espèces réactives de l'oxygène et de l'azote ainsi que des perturbations de la fonction mitochondriale. Nous avons également découvert un nouveau rôle pour transcription factor EB (TFEB), un régulateur clé de la biogenèse des lysosomes, dans la réussite du processus d'adaptation cellulaire. Nous avons montré que la présence d'une coque recouvrant les QD ainsi que des modifications à leur surface peuvent diminuer significativement leur toxicité, et dans certains cas, les rendre non-toxiques. La compréhension des mécanismes d'adaptation cellulaire en réaction aux points quantiques est essentielle au développement de procédés évaluant la sécurité d'autres nanomatériaux.Nous avons par la suite étudié l'effet des propriétés de surface des QD et comment elles contribuent à l'absorption des particules. Nous avons utilisé des points quantiques de même noyau mais ayant des modifications de surface distinctes. Nous avons démontré que la charge de surface des QD joue un rôle important dans leur internalisation cellulaire dans deux lignés de cellules humaines différentes. De plus, nous avons montré que plusieurs modes d'importation et d'exportation de la cellule étaient impliqués dans ce processus. Enfin, nous avons étudié systématiquement les effets des propriétés de surface des QD sur la stabilité des particules dans les milieux biologiques. Nous avons découvert que les protéines du sérum sont différemment adsorbées à la surface des particules ce qui joue un rôle déterminant dans le mode d'intériorisation principal.En conclusion, ces résultats aident au développement de matériaux d'échelle nanométrique de deux façons:1 ) en promouvant les modèles in vitro comme une première étape dans l'évaluation de la sécurité des nanomatériaux.2 ) en démontrant un lien entre la charge de surface ainsi que les propriétés des ligands et les modes spécifiques d'internalisation cellulaire.Les résultats présentés ici contribuent à la compréhension de la complexité de l'interface nano-bio et fournissent des principes directeurs pour la conception minutieuse de nanoparticules, avec une attention particulière pour la taille, la forme et la charge de surface.
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Kozyra, Jerzy Wieslaw. "Computation and programmability at the nano-bio interface." Thesis, University of Newcastle upon Tyne, 2017. http://hdl.handle.net/10443/3694.
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The manipulation of physical reality on the molecular level and construction of devices operating on the nanoscale has been the focal point of nanotechnology. In particular, nanotechnology based on DNA and RNA has a potential to nd applications in the eld of Synthetic Biology thanks to the inherent compatibility of nucleic acids with biological systems. Sca olded DNA origami, proposed by P. Rothemund, is one of the leading and most successful methods in which nanostructures are realised through rational programming of short 'staple' oligomers which fold a long single-stranded DNA called the 'sca old' strand into a variety of desired shapes. DNA origami already has many applications; including intelligent drug delivery, miniaturisation of logic circuits and computation in vivo. However, one of the factors that are limiting the complexity, applicability and scalability of this approach is the source of the sca old which commonly originates from viruses or phages. Furthermore, developing a robust and orthogonal interface between DNA nanotechnology and biological parts remains a signi cant challenge. The rst part of this thesis tackles these issues by challenging the fundamental as- sumption in the eld, namely that a viral sequence is to be used as the DNA origami sca old. A method is introduced for de novo generation of long synthetic sequences based on De Bruijn sequence, which has been previously proposed in combinatorics. The thesis presents a collection of algorithms which allow the construction of custom- made sequences that are uniquely addressable and biologically orthogonal (i.e. they do not code for any known biological function). Synthetic sca olds generated by these algorithms are computationally analysed and compared with their natural counter- parts with respect to: repetition in sequence, secondary structure and thermodynamic addressability. This also aids the design of wet lab experiments pursuing justi cation and veri cation of this novel approach by empirical evidence. The second part of this thesis discusses the possibility of applying evolutionary op- timisation to synthetic DNA sequences under constraints dictated by the biological interface. A multi-strand system is introduced based on an alternative approach to DNA self-assembly, which relies on strand-displacement cascades, for molecular data storage. The thesis demonstrates how a genetic algorithm can be used to generate viable solutions to this sequence optimisation problem which favours the target self- assembly con guration. Additionally, the kinetics of strand-displacement reactions are analysed with existing coarse-grained DNA models (oxDNA). This thesis is motivated by the application of scienti c computing to problems which lie on the boundary of Computer Science and the elds of DNA Nanotechnology, DNA Computing and Synthetic Biology, and thus I endeavour to the best of my ability to establish this work within the context of these disciplines.
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Zhang, Tan Tan. "Nano-watt class CMOS interface circuits for wireless sensor nodes." Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3952097.
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Yu, Zhou. "Surface Polymerization, Interface Structure, and Low Temperature Consolidation of Nano Ceramic Particles." University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin971379308.
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Walker, Nicholas David Leyland. "The role of the nano-environmental interface in ZnO and CeO2 nanoparticle ecotoxicology." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/3734.
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An increase in nanotechnology has seen an associated rise in nanoparticles released into the environment. Their potential toxicity and exposure to humans and the environment, the field of nanoecotoxicology, is not yet well understood. The interactions at the nanoparticle surface will play a fundamental role in the nanoparticle behaviour once released into the environment. This study aims to characterise the particle surface interaction, determining key parameters influential in the nanoparticle fate. Evanescent Wave Cavity Ring Down Spectroscopy techniques have been applied to study molecular interactions at the silica-water charged interface. The adsorption of the electronic spectrum of Crystal Violet has demonstrated the formation of a monolayer with different binding site orientation at the interface. The binding affinity for the chromophore was calculated as 29.15 ± 0.02 kJmol-1 at pH 9 and this was compared with other interface structures involving both inorganic and organic components. The study of the model interface was extended to the properties of CeO2 nanoparticles, where the surface charge density was determined to be 1.6 ± 0.3 e- nm-2.The nanoparticle surface charge controls the suspension stability which was measured for CeO2 nanoparticles giving a stability half-life of 330 ± 60 hours in pure water, and 3.6 ± 0.6 hours in ISOFish water. Studies were extended to the toxicity of ZnO nanoparticles. An assay was developed to quantify the photo-electron production for nanoparticles exposed to UV light both in deionised water and soil suspensions with a photo-radical production yield of 19 ± 2 % and an electron production of 709 e-s-1np-1 for a 100 mgL-1 suspension. The species-specific photo-radical assay was subsequently used to determine the rate of ZnO nanoparticle dissolution in water and soil suspensions. Comparable dissolution rates in complex cell growth media were also measured, detecting total zinc by Inductively Coupled Plasma Atomic Emission Spectroscopy, with comparable dissolution rates derived.
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Zhen, Cao. "Elastocapillarity at Nano- and Micro-Scales: from Wetting and Adhesion to Interface Reinforcement." University of Akron / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=akron1494328999181011.
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Peditto, Francesca. "Photopolymerized micro-and nano-composites : interface chemistry and its role on interfacial adhesion." Lyon, INSA, 2004. http://theses.insa-lyon.fr/publication/2004ISAL0011/these.pdf.
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The aim of this work is to realize epoxy-based UV-cured polymer composites reinforced by nanosilica or glass fibres and to characterize them using specific techniques (ATG, FT-IR, SEM, AFM, wettability measurements, microbond test ). The inorganic surfaces were chemically modified in order to improve their compatibility with the selected polymetric matrix. Their characterization shows that the obtained surface properties promote the chemical interaction between the matrix and the fillers. The influence of the type and treatment of the inorganic filler on the photopolymerization kinetics and on adhesion properties were evaluated. The obtained results show that the presence of inorganic fillers modifies the reaction kinetics and that the surface treatment promotes the formations of strong bonds between the two phases of the composites. Thanks to this work, new composites materials with innovative properties were obtainedLe but de ce travail est de réaliser par photopolymérisation UV des composites à matrice époxy avec soit des nanocharges de silice soit des fibres de verre et de les caractériser à l'aide de techniques appropriées (ATG, FT-IR, SEM, AFM, mouillage, test d'adhérence). Les surfaces inorganiques ont été modifiées par greffage chimique pour optimiser leur compatibilité avec les différentes matrices. La caractérisation montre que les propriétés obtenues améliorent l'interaction chimique entre la matrice et les charges. L'influence de la nature des charges et leur traitement de surface sur les cinétiques de photopolymérisation et l'adhérence ont été évalués. Les résultats montrent que la présence des charges modifie les cinétiques de réaction et que le greffage porte à la formation de liaisons fortes entre les deux phases. L'ensemble de ce travail a permis d'obtenir des matériaux composites ayant des propriétés encore jamais signalées à ce jour
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Radhakrishnan, Vikram. "Cohesive zone modeling of the interface in linear and nonlinear carbon nano-composites." Cincinnati, Ohio : University of Cincinnati, 2008. http://rave.ohiolink.edu/etdc/view.cgi?acc_num=ucin1206453509.
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Thesis (M.S.)--University of Cincinnati, 2008.Advisor: Kumar Vemaganti. Title from electronic thesis title page (viewed Feb.25, 2009). Includes abstract. Keywords: carbon nano-composites; cohesive zone modeling (CZM); interface; finite element analysis. Includes bibliographical references.
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Peditto, Francesca Priola Aldo Gérard Jean-François. "Photopolymerized micro-and nano-composites interface chemistry and its role on interfacial adhesion /." Villeurbanne : Doc'INSA, 2005. http://docinsa.insa-lyon.fr/these/pont.php?id=peditto.
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Jijie, Roxana. "Synthesis and characterization of complex nano-structures at the interface with biological medium." Thesis, Lille 1, 2016. http://www.theses.fr/2016LIL10084/document.
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L’augmentation des infections causées par des pathogènes résistants aux médicaments est devenue un problème de santé majeur dans le monde entier qui impose le développement de nouvelles stratégies destinées à empêcher la formation de biofilms et à éliminer les bactéries. Dans ce contexte, l’objectif de cette thèse a été la préparation de nanostructures complexes pour contrôler l’adhérence des cellules à des surfaces et inactiver les bactéries pathogènes. Ainsi, nous proposons différentes approches qui consistent en l’utilisation de : i) une couche micro-structurée de polystyrène polymérisé à l’aide d’un plasma (pPS), ii) la thérapie photodynamique à base de nanoparticules hybrides activées par un rayon laser dans le proche infrarouge (NIR) et iii) des nanoparticules de carbone fonctionnalisées par l’ampicilline, comme solutions possibles pour éliminer les bactériesThe increase of infections by multi-drug resistant pathogens has become an important worldwide healthcare issue that requires the development of new strategies to prevent biofilm formation and to kill bacteria. In this context, the aim of this thesis was the design of complex nano-structures to control cells adhesion to surfaces and to inactivate pathogenic bacteria. To this end, we propose different strategies relying on the use of i) micro-structured plasma polymerized styrene (pPS) films, ii) particle-based photodynamic therapy combined with a pulsed laser in the near infrared (NIR) region and iii) ampicillin-functionalized, fluorescent carbon dots (CDs) as possible solutions for bacterial killing. Firstly, we performed a detail characterization of pPS films used as substrates to study the behavior of biological systems
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Biehl, Philip [Verfasser], Felix [Gutachter] Schacher, and Thomas [Gutachter] Heinze. "Tailoring the Interface of Magnetic Nano-Composites / Philip Biehl ; Gutachter: Felix Schacher, Thomas Heinze." Jena : Friedrich-Schiller-Universität Jena, 2020. http://d-nb.info/121957404X/34.
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Schwaminger, Sebastian Patrick [Verfasser]. "Nano-bio interactions at the aqueous interface of iron oxide nanoparticles / Sebastian Patrick Schwaminger." München : Verlag Dr. Hut, 2017. http://d-nb.info/1149580178/34.
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Brown, Katherine Alice. "Noncovalent adsorption of nucleotides in gold nanoparticle DNA conjugates : bioavailability at the bio-nano interface." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44866.
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Thesis (Ph. D.)--Massachusetts Institute of Technology, Biological Engineering Division, 2008.Includes bibliographical references (p. 82-92).
The practical viability of biomolecule-nanostructure hybrids depends critically on the functional and structural stability of biomolecules in application environments. Noncovalent interactions of biochemical functional groups with nanostructure surfaces can significantly disrupt biomolecular structure and function. We report a systematic study of the effect of DNA sequence on the binding interaction between gold nanoparticles and thiolated DNA (AuNp-DNA). Base specific noncovalent nucleotide adsorption on gold surfaces can affect nucleotide bioavailability in solution. Systematic investigation of DNA oligonucleotide sequence, the location of specific sequence motifs, and the effect of nanoparticle size was performed. Sequence effects on DNA coverage and oligonucleotide adsorption affinities.were studied by Langmuir isotherm analysis. The nanoparticle coverage at saturating concentrations of thiolated DNA varied with oligonucleotide sequence. Saturation coverages correlated well with complement hybridization efficiency. From this we concluded that noncovalent interactions between nucleotides and the particle surface effect both hybridization and DNA coverage and adsorption. This hypothesis was confirmed by chemical treatment of the particle surface to eliminate noncovalent interactions. Upon treatment the effect of sequence on hybridization efficiency was removed. The effect of sequence is not consistent across nanoparticle sizes. Different bases show the highest saturation coverages and hybridization efficiencies on different AuNp sizes. These results allow for sequence selection guidelines based on AuNp size for sizes ranging from 4-11nm. For smaller particles (<5nm) adenine rich sequences show the highest saturation coverage and hybridization efficiency.
(cont.) For mid-sized particles (~7.5nm), guanine sequences show the highest saturation coverage and hybridization efficiency. Larger particles (>10nm) show little sequence dependent behavior and are likely the best choice for uses where sequence choice is limited. Sequence selection based on these guidelines will provide AuNp-DNA conjugates with the highest possible oligonucleotide bioavailability, maximizing their utility in biotechnology applications.
by Katherine A. Brown.
Ph.D.
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Jespersen, Michael L. 1979. "Engineering the macro-nano interface: Designing the directed self-assembly and interfacial interactions of gold nanoparticle monolayers." Thesis, University of Oregon, 2008. http://hdl.handle.net/1794/7504.
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xviii, 192 p.Gold nanoparticles in the 1-2 mn core diameter size regime have generated a great deal of interest due to their size-dependent electronic, optical, and catalytic properties. A number of proof-of-concept experiments have demonstrated that small metal nanoparticles can be integrated into single electron transistors and optical waveguides. Still, reliable incorporation of gold nanoparticles into devices requires practical methods for their assembly on surfaces. Additionally, surface modification methods must be developed in order to control interparticle interactions and nanoparticle-environment interactions for use in sensing and catalysis. In this research, nanoparticle-substrate interactions were utilized to assemble surface-bound gold nanoparticle monolayers with interesting electronic and catalytic properties. Gold nanoparticles (1.5 nm diameter) with a thiol ligand shell containing phosphonic acid terminal functionality were synthesized and assembled selectively onto hafnium-modified silicon dioxide substrates through bonding of the terminal phosphonate to Hf(IV) surface groups. By increasing the surface coverage of Hf, it was possible to assemble monolayers of gold nanoparticles dense enough to exhibit nonlinear current-voltage properties across a 5-μm electrode gap at room temperature. Moreover, by taking advantage of the selectivity of this ligand shell for ZnO over SiO 2 , small gold nanoparticles were utilized as catalysts for selective growth of patterned, vertical ZnO nanowire arrays. In addition to engineering nanoparticle-substrate interactions, new surface modification methods were introduced to manipulate the interaction of the as-deposited gold nanoparticle monolayers with the environment. For example, thiol-thiol ligand exchange reactions were carried out on the surface-bound nanoparticle monolayers by immersion in dilute thiol solutions. Contact angle and XPS measurements indicate that the upper, surface-exposed phosphonic acid ligands are replaced by incoming thiol ligands. TEM measurements indicate that nanoparticle monolayers remain surface-bound and are stable to this exchange process, as the average particle size and surface coverage are preserved. As another example, the ligand shell can be partially removed by UV/ozone treatment to expose bare gold cores to the surrounding environment. On metal oxide substrates, this approach activates the particles for room temperature oxidation of carbon monoxide to carbon dioxide. This dissertation includes both my previously published and my co-authored materials.
Adviser: James E. Hutchison
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Jespersen, Michael L. "Engineering the macro-nano interface : designing the directed self-assembly and interfacial interactions of gold nanoparticle monolayers. /." Connect to title online (ProQuest), 2007. http://proquest.umi.com/pqdweb?did=1525704531&sid=1&Fmt=2&clientId=11238&RQT=309&VName=PQD.
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Thesis (Ph. D.)--University of Oregon, 2008.Typescript. Includes vita and abstract. Includes bibliographical references (leaves 164-192). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.
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Wang, X., S. Dong, Ashraf F. Ashour, S. Ding, and B. Han. "Bond behaviors between nano-engineered concrete and steel bars." Elsevier, 2021. http://hdl.handle.net/10454/18564.
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YesThis paper investigated the bond characteristics between eight types of nanofillers modified reactive powder concrete (RPC) and plain steel bars, aiming to explore the modifying mechanisms and establish a bond-slip relationship model for nanofillers modified RPC and steel bar interface. The experimental results indicated that the incorporation of nanofillers can increase the bond strength and reduce the slip between RPC and plain steel bars. It was shown that a 2.15 MPa/20.5% of absolute/relative increase in cracking bond strength, a 1.25 MPa/10.3% of absolute/relative increase in ultimate bond strength, a 2.35 MPa/22.4% of absolute/relative increase in residual bond strength, a 0.592 mm/56.5% of absolute/relative reduction in ultimate bond slip, and a 1.779 mm/52.1% of absolute/relative reduction in residual bond slip were the best achieved due to the addition of various nanofillers. The enhancement of nanofillers on RPC-steel bar interface has been mainly attributed to RPC microstructure improvement, optimization of intrinsic compositions, and elimination of defects in the interface, especially the underside near steel bar, due to the nano-core effect of nanofillers enriched in the interface. In addition, the bond-slip relationship of nanofillers modified RPC-steel bar interface can be accurately described by the proposed model considering an initial branch.
The authors would like to thank the funding offered by the National Science Foundation of China (51978127 and 51908103), and the Fundamental Research Funds for the Central Universities (DUT21RC(3)039).
The full-text of this article will be released for public view at the end of the publisher embargo on 22 Jul 2022.
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Li, Kungang. "Investigation of the aggregation of nanoparticles in aqueous medium and their physicochemical interactions at the nano-bio Interface." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/53416.
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Owing to their unique physical, chemical, and mechanical properties, nanoparticles (NPs) have been used, or are being evaluated for use, in many fields (e.g., personal care and cosmetics, pharmaceutical, energy, electronics, food and textile). However, concerns regarding the environmental and biological implications of NPs are raised alongside the booming nanotechnology industry. Numerous studies on the biological effect of NPs have been done in the last decade, and many mechanisms have been proposed. In brief, mechanisms underlying the adverse biological effect caused by NPs can be summarized as: (i) indirect adverse effect induced by reactive oxygen species (ROS) generated by NPs, (ii) indirect adverse effect induced by released toxic ions, and (iii) adverse effect induced by direct interactions of NPs with biological systems. Up to now, most efforts have been focused on the first two mechanisms. In contrast, adverse biological effects induced by direct nano-bio interactions are the least researched. This is largely because of the complexity and lack of suitable techniques for characterizing the nano-bio interface.
This dissertation aims at advancing our understanding of the nano-bio interactions leading to the adverse biological effect of NPs. Specifically, it is comprised of three parts. Firstly, because the aggregation of NPs alters particle size and other physicochemical properties of NPs, the property of NPs reaching and interacting with biological cells is very likely different from that of what we feed initially. Consequently, as the first step and an essential prerequisite for understanding the biological effect of NPs, NP aggregation is investigated and models are developed for predicting the stability and the extent of aggregation of NPs. Secondly, interactions between NPs and cell membrane are studied with paramecium as the model cell. Due to the lack of cell wall, the susceptible cell membrane of paramecium is directly exposed to NPs in the medium. The extent and strength of direct nano-cell membrane interaction is evaluated and quantified by calculating the interfacial force/interaction between NPs and cell membrane. A correlation is further established between the nano-cell membrane interaction and the lethal acute toxicity of NPs. We find NPs that have strong association or interaction with the cell membrane tend to induce strong lethal effects. Lastly, we demonstrate systematic experimental approaches based on atomic force microscope (AFM), which allows us to characterize nano-bio interfaces on the single NP and single-molecular level, coupled with modeling approaches to probe the nano-DNA interaction. Using quantum dots (QDs) as a model NP, we have examined, with the novel application of AFM, the NP-to-DNA binding characteristics including binding mechanism, binding kinetics, binding isotherm, and binding specificity. We have further assessed the binding affinity of NPs for DNA by calculating their interaction energy on the basis of the DLVO models. The modeling results of binding affinity are validated by the NP-to-DNA binding images acquired by AFM. The investigation of the relationship between the binding affinity of twelve NPs for DNA with their inhibition effects on DNA replication suggests that strong nano-DNA interactions result in strong adverse genetic effects of NPs.
In summary, this dissertation has furthered our understanding of direct nano-bio interactions and their role in the biological effect of NPs. Furthermore, the models developed in this dissertation lay the basis for building an “ultimate” predictive model of biological effects of NPs that takes into account multiple mechanisms and their interactions, which would save a lot of testing costs and time in evaluating the risk of NPs.
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Boufarguine, Majdi. "Etude de la déformation de gouttes à interface et rhéologie complexes." Phd thesis, Université du Maine, 2011. http://tel.archives-ouvertes.fr/tel-00954404.
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Ce travail de thèse est une contribution à l'étude des émulsions de Pickering qui ont vu unregain d'intérêt ces dernières années. Bien que l'effet Pickering ait été décrit depuis plus d'un siècle,des études plus systématiques pour comprendre l'activité des particules solides aux interfacesliquide/liquide n'est que partiellement entrepris, surtout en cours de déformation. Plusieurs questionsrestent d'actualité et, en premier, la localisation même des particules à l'interface et le mécanismed'adsorption associé.L'approche proposée dans ce travail de thèse s'inscrit dans cette optique avec en particulier laconsidération d'un événement élémentaire d'une émulsion : une goutte isolée dans une matrice etexaminée suite à un saut de déformation en cisaillement dans un dispositif de cisaillement contrarotatifdéveloppé à PCI. De manière générique, le but est de comprendre la relation entre le comportement dela goutte et la rhéologie complexe (en volume ou en surface) apportée par la dynamique de particulessolides aux interfaces liquide/liquide mobiles. Plusieurs paramètres ont été étudiés en commençant parl'affinité chimique des particules solides avec les phases liquides, la rhéologie des phases liquides, laconcentration et la taille des particules solides ; et pour finir, une attention particulière a été portée àl'effet de la déformation macroscopique et l'âge de la goutte.Plus particulièrement, la mise en évidence de la synergie entre la déformation macroscopiqueet l'âge de la goutte, sur la dynamique d'adsorption des particules à l'interface liquide/liquide et lastructuration de l'interface composée, a permis de proposer une méthodologie pour la modulation de" l'effet mémoire induite par la déformation " lors de la relaxation de la goutte en modifiant lasurface des particules par adsorption de tensioactifs choisis. Ainsi, il a été possible de figer les gouttesliquides dans des formes anisotropes contrôlées. Ce phénomène a été corrélé à une transition liquidesolidede l'interface composée mise en évidence par des mesures des modules rhéologiquesinterfaciaux. Ces derniers ont été, par ailleurs, reliés quantitativement à l'anisotropie des gouttesfigées.
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Wurster, Eva-Christina [Verfasser], and M. [Akademischer Betreuer] Breunig. "Layer-by-Layer assembled thin films for drug delivery: Interactions at the nano-bio interface / Eva-Christina Wurster. Betreuer: M. Breunig." Regensburg : Universitätsbibliothek Regensburg, 2016. http://d-nb.info/110322901X/34.
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Zell, Philipp. "Design of functionalised ligands and metal complexes for self-assembly at the liquid/solid interface: STM-visualisation of 2D nano-patterns." [S.l. : s.n.], 2006. http://nbn-resolving.de/urn:nbn:de:bsz:289-vts-56638.
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Mahalingam, Sakethraman. "Study of Interfacial Crack Propagation in Flip Chip Assemblies with Nano-filled Underfill Materials." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7215.
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No-flow underfill materials that cure during the solder reflow process is a relatively new technology. Although there are several advantages in terms of cost, time and processing ease, there are several reliability challenges associated with no-flow underfills. When micron-sized filler particles are introduced in no-flow underfills to enhance the solder bump reliability, such filler particles could prevent the solder bumps making reliable electrical contacts with the substrate pads during solder reflow, and therefore, the assembly yield would be adversely affected. The use of nano-sized filler particles can potentially improve assembly yield while offering the advantages associated with filled underfill materials.
The objective of this thesis is to study the thermo-mechanical reliability of nano-filled epoxy underfills (NFU) through experiments and theoretical modeling. In this work, the thermo-mechanical properties of NFUs with 20-nm filler particles have been measured. An innovative residual stress test method has been developed to measure the interfacial fracture toughness. Using the developed residual stress method and the single-leg bending test, the mode-mixity-dependent fracture toughness for NFU-SiN interface has been determined. In addition to such monotonic interfacial fracture characterization, the interface crack propagation under thermo-mechanical fatigue loading has been experimentally characterized, and a model for fatigue interface crack propagation has been developed. A test vehicle comprising of several flip chips was assembled using the NFU material and the reliability of the flip-chip assemblies was assessed under thermal shock cycles between -40oC and 125oC. The NFU-SiN interfacial delamination propagation and the solder bump reliability were monitored. In parallel, numerical models were developed to study the interfacial delamination propagation in the flip chip assembly using conventional interfacial fracture mechanics as well as cohesive zone modeling. Predictions for interfacial delamination propagation using the two approaches have been compared. Based on the theoretical models and the experimental data, guidelines for design of NFUs against interfacial delamination have been developed.
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Park, So Jeong. "Propriétés électriques et modélisation des dispositifs MOS avanvés : dispositif FD-SOI, transistors sans jonctions (JLT) et transistor à couche mince à semi-conducteur d'oxyde amorphe." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00954637.
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Selon la feuille de route des industriels de la microélectronique (ITRS), la dimension critiqueminimum des MOSFET en 2026 ne devrait être que de 6 nm [1]. La miniaturisation du CMOS reposeessentiellement sur deux approches, à savoir la réduction des dimensions géométriques physiques etdes dimensions équivalentes. La réduction géométrique des dimensions conduit à la diminution desdimensions critiques selon la " loi " de Moore, qui définit les tendances de l'industrie dessemiconducteurs. Comme la taille des dispositifs est réduite de façon importante, davantage d'effortssont consentis pour maintenir les performances des composants en dépit des effets de canaux courts,des fluctuations induites par le nombre de dopants.... [2-4]. D'autre part, la réduction des dimensionséquivalentes devient de plus en plus importante de nos jours et de nouvelles solutions pour laminiaturisation reposant sur la conception et les procédés technologiques sont nécessaires. Pour cela,des solutions nouvelles sont nécessaires, en termes de matériaux, d'architectures de composants et detechnologies, afin d'atteindre les critères requis pour la faible consommation et les nouvellesfonctionnalités pour les composants futurs ("More than Moore" et "Beyond CMOS"). A titred'exemple, les transistors à film mince (TFT) sont des dispositifs prometteurs pour les circuitsélectroniques flexibles et transparents.
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Kostick, Nathan H. "Novel Carbon-Nanotube Based Neural Interface for Chronic Recording of Glossopharyngeal Nerve Activity." Case Western Reserve University School of Graduate Studies / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=case1517920588275806.
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Wang, Yifang. "Pulmonary toxicity assessment following aerosolization of engineered nanomaterials using an in vitro air-liquid interface method." Thesis, University of Iowa, 2019. https://ir.uiowa.edu/etd/7044.
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Although there are over 1,600 Engineered Nanomaterials (ENMs)-containing consumer products available, our understanding of ENM safety is still limited. Airborne ENMs can readily enter the human body through inhalation potentially leading to many adverse health effects such as cardiovascular and pulmonary diseases. The conventional in vitro submerged cell culture method was developed decades ago and has been widely used as a fast screening method to elucidate cellular toxicity upon exposure to hazardous materials; however, it has many limitations compared with the in vivo models. Our group has previously utilized and validated an integrated low flow system capable of generating and depositing airborne nanoparticles (NPs) directly onto cells at an air-liquid interface (ALI) condition, and our results confirmed that this exposure system produced reproducible toxicological data for ENMs including gold (Au), 16% silver coated onto silica (16% Ag-SiO2), and copper oxide (CuO). To further improve this ALI method for an even closer representation of the in vivo model, a co-culture model containing three cell lines (A549, THP-1 differentiated macrophages, and EA.hy 926) was established and validated for testing ENMs toxicity. The co-culture model was exposed to 16% Ag-SiO2 and CuO NPs under the same protocol (4 h ALI exposure with a concentration of 3.5 mg/m3) as monoculture (A549 only) for comparison. Toxicity was assessed by measuring cell viability, reactive oxygen species (ROS) production, lactate dehydrogenase (LDH) release, and interleukin (IL) 8 level. Results showed that 16% Ag-SiO2 NPs induced higher ROS generation, and CuO NPs produced a significant level of proinflammatory response compared with monoculture. In addition, the co-culture model exhibited a similar response with the primary human bronchial epithelia cell line (HBEC) in terms of ROS and IL-8 responses after CuO NPs exposure, suggesting a more advanced refinement of the conventional model for in vitro inhalation study.
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Wu, Mingjian. "Advanced transmission electron microscopy investigation of nano-clustering in Gd-doped GaN." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2014. http://dx.doi.org/10.18452/16950.
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Das zentrale Ziel der vorliegenden Arbeit besteht einerseits darin, die Verteilung von Gd in GaN:Gd mit Gd-Konzentrationen von 10^16–10^19 cm^-3 mittels fortgeschrittener (Raster-) Transmissionselektronenmikroskopie [(S)TEM] zu bestimmen. Darauf basierend wird zum anderen das Verständnis des Mechanismus, der diese Verteilungen bewirkt, entwickelt. Wir diskutieren detailliert die Anwendung und die Grenzen von (S)TEM-Abbildungsmethoden und quantitativen Analysenmethoden und von Modellierungsmethoden, um Nano-Cluster in epitaktischen Halbleiterschichten zu beobachten und zu analysieren. Außerdem werden Fallstudien zweier Materialsysteme betrachtet, die offensichtlich Nano-Cluster aufweisen. Schließlich sind wir in der Lage, die in GaN:Gd auftretenden GdN-Cluster zu identifizieren und ihre atomare Struktur zu bestimmen. Dehnungskontrastabbildungen mit Kontrastberechnungen belegen eindeutig das Auftreten von kleinen, plättchenförmigen GdN-Clustern. Diese Cluster weisen nahezu gleiche Abmessungen auf und liegen mit der ausgedehnten Fläche parallel zu den GaN(0001)-Basalebenen. Dieses Ergebnis wird durch Dunkelfeld-STEM-Abbildungen (Z-Kontrast), bestätigt. Die starke, lokale Gitterdehnung (Verzerrungsfeld), die durch die Cluster hervorgerufen wird, ist in HRTEM-Aufnahmen abgebildet und quantitativ ausgewertet worden. Durch den Vergleich von Verzerrungsfeldern, die experimentell ermittelt worden sind, mit theroretischen Feldern schließen wir auf Cluster aus zweilagigen GdN-Plättchen mit einem Durchmesser von wenigen Gd-Atomen. Ihre interne Struktur entspricht etwa der NaCl-Phase des GdN. Dieses atomare Strukturmodell erlaubt unsere Diskussion der Energieverhältnisse der Cluster. Die Ergebnisse implizieren, dass die treibende Kraft für die beobachtete Plättchengröße ein Gleichgewicht zwischen der Zunahme von kohäsiver Energie und der Einschränkung durch die Dehnungsenergie an der Grenzfläche zwischen GdN-Cluster und GaN-Wirtsgitter aufgrund der Gitterfehlanpassung ist.The central goal of this dissertation is (1) to clarify the distribution of Gd atoms in GaN:Gd with Gd concentration in the range between 10^16–10^19 cm^-3 by means of advanced (scanning) transmission electron microscopy [(S)TEM]; and based on that, (2) to understand the mechanisms that control such distribution. We discuss in detail the application and limitations of (S)TEM imaging and analysis techniques and modeling methods dedicated to the study of embedded nano-clusters. Besides, two case studies of semiconductor material systems that contain apparently observable nano-clusters are considered. One is about intentionally grown InAs nano-clusters embedded in Si and the other study the formation and phase transformation of Bi-containing clusters in annealed GaAsBi epilayers. Finally, we are able to identify the occurrence of GdN clusters in GaN:Gd samples and to determine their atomic structure. Strain contrast imaging in conjunction with contrast simulation unambiguously identifies the occurrence of small, platelet-shaped GdN clusters. These clusters are nearly uniform in size with their broader face parallel to the GaN (0001) basal plane. The result is confirmed by dark-field STEM Z-contrast imaging. The strong local lattice distortion (displacement field) induced by the clusters is recorded by HRTEM images and quantitatively analyzed. By comparing the displacement fields which are analyzed experimentally with these fields that are derived from energetically favored models, we conclude that the clusters are bilayer GdN with platelet diameter of only few Gd atoms; their internal structure is close to rocksalt GdN. This atomic structure model enables our discussion about the energetics of the clusters. The results indicate that the driving force for the formation of observed platelet in specific size is a compromise between the gain in cohesive energy and the penalty from interfacial strain energy due to lattice mismatch between the GdN cluster and GaN host.
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Béjaud, Romuald. "Formation et extension de macles de déformation dans des nanostructures cfc : simulations numériques." Thesis, Poitiers, 2017. http://www.theses.fr/2017POIT2318.
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Depuis quelques dizaines d'années, l'élaboration de matériaux nanostructurés tend de plus en plus à se développer. En effet, ces matériaux présentent souvent des propriétés intéressantes et en particulier des propriétés mécaniques surprenantes vis-à-vis de leurs homologues sous forme massive. Les métaux nano-maclés ou nano-lamellaires par exemple, sont connus pour avoir une bonne résistance mécanique, une bonne stabilité thermique et une excellente résistance aux radiations. Au fur et à mesure que l'espacement entre les interfaces diminue, leur densité augmente de manière significative et les propriétés macroscopiques du matériau sont de plus en plus dépendantes des interactions défaut-interface. Dans ce contexte, nous avons étudié, via des simulations atomistiques, la formation de macles de déformation et les mécanismes d'interaction d'une macle nouvellement formée avec une interface préexistante (un joint de macle ou une interface entre 2 métaux), pour une configuration modèle de film mince auto-supporté. Des premiers résultats montrent l'influence de marches de surface sur le maclage, pour un cas modèle sans interface. Puis nous avons identifié un mécanisme inédit aboutissant à la formation d'une dislocation de Lomer suite à l’interaction d'une macle en formation avec un joint de macle préexistant. En faisant varier la densité de défauts de surface, nous montrons l'influence particulière d'un joint de macle sur la taille et le nombre de macles formées. Enfin, pour les systèmes bimétalliques Cu/Ag, nos résultats mettent en évidence le rôle des dislocations d'épitaxie (à l'interface) dans la nucléation et l'extension des macles ainsi qu'une influence directe du type d'interface considéré sur la propagation de ces maclesFor several decades, the elaboration of nano-structured materials tends to develop more and more. Indeed, these materials often show interesting properties, and in particular surprising mechanical properties when compared to their bulk counterparts. For example, nano-twinned or nano-layered metals are known to have ultra-high mechanical strength, good thermal stability, and very good radiation resistance. As the interface spacing decreases to the nanometer-scale, the density of interfaces increases significantly and subsequently the macroscopic properties become largely governed by the interface-defect interactions. In that context, we have studied deformation twin formation and mechanisms of interaction between a new formed twin and a preexisting interface (a twin boundary or a bimetallic interface), using atomistic simulations and a thin film model configuration. First results show the influence of surface steps on mechanical twinning, for a model system without interface. Then we identify a new mechanism leading to the formation of a Lomer dislocation, following the interaction of a newly formed twin and a preexisting twin boundary. By varying the density of surface defects, we show the particular influence of a preexisting twin boundary on twin size and number. Finally, for the Cu/Ag bimetallic system, our results highlight the role of epitaxial dislocations (at the interface) in twin nucleation and extension as well as a direct influence of the interface type in twin propagation
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Alaili, Kamal. "Transport de chaleur dans les nano-couches minces excitées par une source laser d'intensité modulée." Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2314.
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Ce travail, divisé en deux parties principales, porte sur l’étude du transport de chaleur dans les nano-couches excitées par une source laser d'intensité modulée. Dans la première partie, nous exploitons la solution analytique de l’équation de transport de Boltzmann appliquée aux phonons pour décrire les variations de la température et du flux de chaleur dans les films minces diélectriques excités par un laser d’intensité modulée. Cette dernière solution nous permet de modéliser le comportement de la résistance thermique d’interface (RTI) entre deux couches diélectriques en fonction de la nature du régime du transport des phonons et de la fréquence de modulation. Dans le régime stationnaire, nous montrons que cette résistance d’interface présente un caractère non-intrinsèque et asymétrique par rapport aux propriétés des deux couches. En plus, elle devient très importante quand le régime du transport des phonons est balistique. Nos résultats sont en bon accord avec le modèle DMM dans le régime balistique, tandis que l’écart entre les deux modèles ne dépasse pas 16% dans le régime diffusif. Cependant, en régime dynamique, la RTI atteint son maximum à une fréquence caractéristique dans la limite diffusive. L’expression de cette fréquence caractéristique pourrait servir à déterminer le libre parcours moyen et le temps de relaxation des phonons dominants de la couche d’épaisseur finie en comparant les données expérimentales aux résultats théoriques. Dans la seconde partie, nous proposons trois différentes méthodes pour extraire simultanément la diffusivité et la conductivité thermiques d’une couche finie en se basant sur l’équation de la chaleur de Fourier. L’idée est d’utiliser l’expression exacte du profil de température à la face avant lorsque celle-ci est excitée par un flux thermique modulé, tandis que la face arrière peut être maintenue à trois différentes conditions : température modulée, flux thermique modulé où température constante. Nous déterminons les expressions des fréquences de modulation auxquelles le profil de température atteint ses premiers maximum et minimum. La combinaison de ces fréquences caractéristiques avec le rapport entre les premiers maximum et minimum de la température, conduit ainsi à la détermination de la diffusivité et de la conductivité thermiquesThis work, separated into two main parts, deals with the study of heat transport in nano-layers excited by a laser beam with modulated intensity. In the first part, we exploit the analytical solution of the phonon Boltzmann transport equation to describe the variations of temperature and heat flux in thin dielectric films excited by a laser beam of modulated intensity. This last solution allows us to model the behavior of the interface thermal resistance (ITR) between two dielectric layers according to the nature of the phonon transport regime and the modulation frequency. In the steady state regime, we show that this interface resistance has a non-intrinsic and asymmetric character with regard to the two layers properties. In addition, it becomes very important when the phonon transport regime is ballistic. Our results are in good agreement with the DMM in the ballistic regime, while they differ by about 16% in the diffusive regime. However, in the dynamical regime, we mainly show that in the diffusive regime, the ITR reaches a maximum at a characteristic modulation frequency. The expression of this characteristic frequency can thus be used to determine the dominant phonons mean free path and relaxation time through the comparison of the theoretical model and the experimental data. In the second part, we propose three different ways to extract simultaneously the thermal diffusivity and conductivity of a finite layer based on the Fourier heat equation. The idea is to use the exact expression of the temperature profile at the front surface of the thin layer when the latter is excited by a periodic heat flux, while the rear surface can be maintained at one of three different types of boundary conditions: modulated periodic heat flux, modulated temperature, or constant temperature. We determine the expressions of the modulation frequencies at which the front surface temperature reaches its first maximum and first minimum. The combination of these characteristic frequencies with the ratio between the first maximum and the first minimum of the temperature, thus leads to the determination of the diffusivity and thermal conductivity
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Auffan, Melanie. "NANOPARTICULES D'OXYDES MÉTALLIQUES : RELATIONS ENTRE LA RÉACTIVITE DE SURFACE ET DES RÉPONSES BIOLOGIQUES." Phd thesis, Université Paul Cézanne - Aix-Marseille III, 2007. http://tel.archives-ouvertes.fr/tel-00348650.
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Les nanotechnologies génèrent un engouement assimilable à une révolution technologique. Le domaine de l'environnement est concerné car les nanoparticules (NPs) apportent des solutions à plusieurs problèmes de pollution. Par exemple, nous avons montré la forte capacité de rétention de l'As (8As/nm2) par des NPs d'oxydes de fer (6nm). Ceci est lié à leur grande surface spécifique et à leur forte réactivité de surface due à la présence de sites d'adsorption inédits et à la diminution significative de l'énergie de surface lors de l'adsorption. Mais des questions se posent sur l'impact (éco)toxicologique engendré par la forte production de NPs. Une classification de l'(éco)toxicité des nano-oxydes en fonction de leurs propriétés redox a été proposée. Alors que des NPs chimiquement stables (γFe2O3) en milieux biologiques ne montrent aucune toxicité, des NPs ayant un pouvoir oxydant (CeO2) ou réducteur (Fe°) sont cytotoxiques pour Escherichia coli et génotoxiques pour les fibroblastes humains.
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Viapiana, Raqueli. "Physicochemical and mechanical properties, bioactivity potential and characterization of the dentin-sealer interface of experimental root sealers based on portland cement with micro and nano particulate radiopacifiers = Propriedades físico-químicas e mecânicas, potencial bioativo e caracterização da interface dentina-cimento de cimentos endodônticos experimentais à base de cimento Portland associados à radiopacificadores micro e nanoparticulados /." Araraquara, 2014. http://hdl.handle.net/11449/122166.
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Orientador: Mário Tanomaru FilhoBanca: José Mauricio dos Santos Nunes Reis
Banca: Josette Camilleri
Banca: Marcos Húngaro Duarte
Banca: Loise Pedrosa Salles
Resumo: O cimento Portland é constituído por silicato de cálcio e a associação com aditivos e veículos conferem características que podem viabilizar seu uso como cimento endodôntico. No entanto, o cimento Portland não apresenta radiopacidade própria, o que torna necessário a adição de um agente radiopacificador à mistura para ser utilizado como material dentário. O objetivo deste estudo foi avaliar as propriedades físico-químicas e mecânicas, o potencial bioativo e caracterizar a interface dentina-cimento de cimentos endodônticos experimentas à base de cimento Portland (ES) contendo nano ou micro partículas de óxido de zircônio ou óxido de nióbio. O tempo de presa, resistência à compressão, escoamento, espessura de filme, radiopacidade, solubilidade e estabilidade dimensional foram avaliadas de acordo com a norma ISO 6876:2012, enquanto que a liberação de fomaldeído foi avaliada por meio de cromatografia gasosa. A resistência de união dentinária foi avaliada por meio de teste push-out e tanto a caracterização da microestrutura dos cimento quanto a análise do potencial bioativo foram realizadas utilizando energia dispersiva de raios-x, difractometria e espectroscopia infravermelha. A interface dentina-cimento foi avaliada com relação à penetração de microesferas fluorescentes e examinada em microscopia confocal e microscopia eletrônica de varredura associada à escaneamento por energia dispersiva de raios-x linear. Os dados foram submetidos aos testes ANOVA e Tukey (p < 0,05). Com exceção da radiopacidade, os ES apresentaram propriedades físico-químicas de acordo com as especificações ISO 6876, adequada resistência de união à dentina, potencial bioativo e promoveram selamento coronário e interação química com a dentina.
Abstract: Portland Cement is composed by calcium silicate and the association with additives or vehicles, may confer characteristics to enable the use of this cement as root canal sealer. However, Portland cement lacks in radiopacity which requires the addition of a radiopacifying agent to the mixture to be used as dental material. The purpose of this study was to assess the physicochemical and mechanical properties, the bioactivy potential and to characterize the dentin-sealers interfaces of Portland-based experimental root canal sealers (ES) containing nano or micro particles of zirconium oxide or niobium oxide. Setting time, compressive strength, flow ability, film thickness, radiopacity, solubility and dimensional stability were evaluated according to ISO 6876:2012 standards, whereas formaldehyde realease was investigated using gas-cromatography. Dentin bond strength was evaluated by push-out test and the sealer's microestruture and bioactivity potential were perfomed using X-ray energy espectroscopy, X-ray diffractometry and infrared spectroscopy. Dentin-sealers interface was assessed with respect to fluorescent microspheres penetration and it was also examined using confocal microscope and scanning electron microscope coupled to X-ray energy dispersive line scans. Data were analyzed by ANOVA and Tukey post-hoc test (p < 0.05). With the exception of radiopacity, ES showed physicochemical properties according to ISO 6876:2012 specifications, adequate dentin bond strength, great bioactivity potential and promoted coronal sealing and chemical interaction with dentin.
Doutor
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Moraes, Fábio Rogério de 1984. "Revelando as características do nano-ambiente das interfaces entre proteinas." [s.n.], 2012. http://repositorio.unicamp.br/jspui/handle/REPOSIP/316805.
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Orientador: Goran NeshichTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-20T22:35:51Z (GMT). No. of bitstreams: 1 Moraes_FabioRogeriode_D.pdf: 15399723 bytes, checksum: 4f1315f86b2c74d078c5105b299a9750 (MD5) Previous issue date: 2012
Resumo: Dentro do ambiente celular, há uma variedade de moléculas e a interação entre si regulam praticamente todos os processos necessários e essenciais para a manutenção da vida. Interações entre proteínas estão envolvidas no controle de vários processos intra e intercelulares, como regulação metabólica e da expressão gênica, reconhecimento antígeno-anticorpo etc. que definem as características biológicas do funcionamento da vida entre os diversos organismos. Ao conhecer a interface de interação de uma proteína chave para desenvolvimento de casos patológicos, é possível desenhar drogas com alta especificidade com o sítio de ligação. Para avançar nessa frente, o conhecimento da estrutura proteica é fundamental, porém não suficiente. É necessário conhecermos o sítio de ligação alvo para cada parceiro de interação. Este estudo visa entender as características do nano-ambiente das interfaces proteicas - área através da qual as macromoléculas se comunicam e exercem sua funcionalidade. Propomos utilizar uma abordagem de estudo das características físico-químicas e estruturais dos resíduos formadores de interfaces de complexos conhecidos e com estrutura quaternária resolvida experimentalmente, utilizando um conjunto de dados sem redundância sequencial, extraindo os parâmetros/descritores que descrevem de forma objetiva as diferentes classes de complexos, revelando as características principais sobre interações proteína-proteína. A finalidade deste trabalho é de conhecer os detalhes que definem uma área como interface e aplicá-lo em uma ferramenta preditiva para todas as proteínas com arranjo estrutural conhecido e/ou modelado. Propomos de forma pioneira, o uso de classificadores específicos para cada tipo de aminoácido e independente do uso de descritores sobre conservação de aminoácidos. Resultados obtidos com classificador linear e por ensemble de redes neurais destacam a nossa abordagem, desenhada e aplicada nesta tese, como uma com os melhores indicadores de desempenho na predição precisa dos resíduos de aminoácido na interface entre as abordagens descritas recentemente na literatura. Ainda, enquanto os outros métodos dependem de descritores sobre conservação de aminoácidos, é mostrado aqui que nenhum ganho de desempenho é obtido com a incorporação de tais descritores em nosso modelo classificador. Esse resultado indica que o uso de descritores puramente físico-químicos e estruturais é suficiente para explicar o grau de conservação dos aminoácidos
Abstract: Inside cells, there is a variety of molecules and their interactions regulate virtually all necessary and essential processes to the maintenance of life. Interactions among proteins are involved in the control of several processes within and out of the cell, such as, metabolic and gene expression regulation, anti-body and antigen recognition, etc. that defines biological characteristics of life among many organisms. If the protein interface amino acids of a key protein related to a given pathologic phenomenon are known, it is possible to rationally design drugs with high specificity for a specific binding site. To gain insight in this field, the knowledge of the protein three-dimensional structure is mandatory, but not sufficient. It is also necessary to know the interface between the target protein and its partners. This study focuses in understanding the characteristics of the area through which the macromolecules communicate to each other and exercise their function. Here, it is proposed an approach to study the physicochemical and structural characteristics of the interface forming residues with known quaternary structure (experimentally solved). It was selected a sequence non-redundant dataset and by extracting parameters/descriptors, that objectively describe different complex classes, it was possible to unravel the basic characteristics of protein-protein binding. The goal of this study is to unravel the details that outline a specific area as interface and apply it in a form of a predictive tool for all proteins with known atomic structure. It is proposed by the first time, the use of amino acid specific classifiers regarding amino acid type and free of amino acid conservation attributes. The results obtained here by employing linear and ensemble of neural network classifiers show that, based on purely physicochemical and structural descriptors, it is possible to get precise predictions about interface forming residues in protein-protein assemblies. Comparatively, the method described here retains better performance indicators than the ones recently described in the literature. In addition, we showed that, for our method, adding "conservation" attributes does not induce any performance gain, which is a major difference if compared to other described methods. This result indicates the purely physicochemical and structural descriptors are sufficient to explain how conserved amino acids are
Doutorado
Bioinformatica
Doutor em Genetica e Biologia Molecular
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Штогрин, Павло Петрович. "Мобільний додаток для моніторингу та прогнозування погодних умов у реальному часі." Bachelor's thesis, КПІ ім. Ігоря Сікорського, 2020. https://ela.kpi.ua/handle/123456789/34793.
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Кваліфікаційна робота включає пояснювальну записку (74 стор., 47 рис.).
У бакалаврському проєкті реалізовано систему для моніторингу та прогнозування погодних умов у реальному часі. Система складається із пристрою для зчитування та передачі через bluetooth даних про погоду, серверної частини для обробки та передачі даних із погодних сервісів у мережі Internet, а також мобільного додатку для прийому, обробки та відображення інформації, отриманої із пристрою та сервера.
Метою проєкту є створення пристрою, який міг би передавати дані про погодні умови безпосередньо у смартфон, а також мобільного додатку із зручним інтерфейсом, який міг би приймати, обробляти та відображати ці дані.
У цьому проєкті було розроблено такі компоненти:
– апаратний засіб на основі платформи Arduino, датчика та bluetooth-передавача;
– сервер, створений мовою програмування Python на базі мікрофреймворку Flask та із використанням REST-архітектури;
– мобільний додаток, створений мовою програмування Java для пристроїв з операційною системою Android;
Результатом розробки є апаратний та програмний продукти, які дозволяють зручно відстежувати поточні погодні умови, а також формують прогноз для конкретної місцевості. Додаток має простий та зрозумілий інтерфейс, мінімальні системні вимоги (пристрій із операційною системою Android версії 4.4 чи вище, bluetooth-модуль та доступ до мережі Internet). Режим моніторингу може працювати без доступу до мережі Internet.The bachelor's project implements a system for monitoring and forecasting weather conditions in real time. The system consists of a device for reading and transmitting weather data via bluetooth, a server part for processing and transmitting data from weather services on the Internet, and a mobile application for receiving, processing and displaying information received from the device and server. The aim of the project is to create a device that could transmit weather data directly to a smartphone and a mobile application with a user-friendly interface that could receive, process and display this data. The following components were developed in this project: − device based on Arduino platform, sensor and bluetooth transmitter; − a server which was created in the Python programming language, based on the Flask microframework and using the REST architecture; − mobile application created in the Java programming language for devices with the Android operating system; The result of the development is hardware and software products that allow conveniently track current weather conditions and form a forecast for a specific area. The application has a simple and clear interface, minimum system requirements (device with Android operating system version 4.4 or higher, bluetooth module and Internet access). The monitoring mode can work without Internet access.
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Karevan, Mehdi. "Understanding effects of nano-reinforcement-matrix interphase on the elastic response of polymer nanocomposites." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/52916.
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Current technology of polymer nanocomposites (PNC) emphasizes the need for fundamental understanding of the links between manufacturing method and macro-scale properties in order to engineer processing and performance of PNCs. The manufacturing method is one key variable that dramatically defines interfacial interactions on the nano-scale and thus the properties of polymer near the interface of nanomaterial/polymer or interphase, level of dispersion and the crystallization behavior of semi-crystalline PNCs. These factors in particular govern reinforcing mechanisms at the interface and consequently impart important properties to PNCs. The current approach to manufacturing PNCs involves trial and error with elaborate, costly and time consuming experimental characterization of PNCs. Therefore, a deep insight into the links among manufacturing method, interfacial interactions and bulk properties is essential in order to design and fabricate PNCs with engineered performance.
The main goal of this study was to provide a better understanding of the effect of manufacturing methods on the macro-scale properties of PNCs, with a focus on the role of interfacial interactions, that can lead to fabrication of PNCs with multifunctional performance. The objectives of this research were to: i) determine the detail correlations among manufacturing method, nano- and microstructure and macro-scale properties of multifunctional exfoliated graphite nanoplatelets/polyamide 12 polymer nanocomposites with enhanced mechanical and electrical performance through systematic manufacturing and experimental methodologies, ii) understand correlations among nano-scale interfacial interactions, physical and structural properties of the polymer at the interface and macro-scale behavior of PNCs, and iii) evaluate effect of manufacturing method on electrical behavior of PNCs with directionally dependent performance.
This study demonstrated key correlations among manufacturing techniques, interfacial interactions and macro-scale properties of PNCs. A methodology was introduced to understand and determine the characteristics of a complex constrained region produced at the interface of nanomaterials and polymer in semi-crystalline PNCs. Finally, the study illustrated superior electrical and morphological properties of selective laser sintering (SLS) processed parts over injection molded PNCs and thus confirmed the capability of SLS in the development of electrically conductive PNCs that exhibit multifunctional performance. In conclusion, the study provided an insight into the links among process, nano-scale interfacial interactions and microstructure to better understand effects of manufacturing technique on macro-scale properties of PNCs, which enables fabrication of conductive PNCs with multifunctional performance.
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Villar, Gabriel. "Aqueous droplet networks for functional tissue-like materials." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:602f9161-368c-48c0-9619-7974f743f2f2.
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An aqueous droplet in a solution of lipids in oil acquires a lipid monolayer coat, and two such droplets adhere to form a bilayer at their interface. Networks of droplets have been constructed in this way that function as light sensors, batteries and electrical circuits by using membrane proteins incorporated into the bilayers. However, the droplets have been confined to a bulk oil phase, which precludes direct communication with physiological environments. Further, the networks typically have been assembled manually, which limits their scale and complexity. This thesis addresses these limitations, and thereby enables prospective medical and technological applications for droplet networks. In the first part of the work, defined droplet networks are encapsulated within mm-scale drops of oil in water to form structures called multisomes. The encapsulated droplets adhere to one another and to the surface of the oil drop to form interface bilayers that allow them to communicate with each other and with the surrounding aqueous environment through membrane pores. The contents of the droplets can be released by changing the pH or temperature of the surrounding solution. Multisomes have potential applications in synthetic biology and medicine. In the second part of the work, a three-dimensional printing technique is developed that allows the construction of complex networks of tens of thousands of heterologous droplets ~50 µm in diameter. The droplets form a self-supporting material in bulk oil or water analogous to biological tissue. The mechanical properties of the material are calculated to be similar to those of soft tissues. Membrane proteins can be printed in specific droplets, for example to establish a conductive pathway through an otherwise insulating network. Further, the networks can be programmed by osmolarity gradients to fold into designed shapes. Printed droplet networks can serve as platforms for soft devices, and might be interfaced with living tissues for medical applications.
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Djurberg, Viktor. "Tailoring the Magnetic Properties of Amorphous TbCo Nano Films." Thesis, Uppsala universitet, Materialfysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-348209.
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The possibility to change magnetic anisotropy of amorphous TbCo films from out-of-plane to in-plane has been investigated. The effects of TbCo film's thickness and composition on the magnetic anisotropy were investigated together with the effects of growing the TbCo films on a SmCo seed layer. This was studied by sputtering TbCo films of composition Tb_xCo_(100-x) x=16,18,20,22 and 24, with thickness ranging between 2-20 nm, with and without the presence of a 20 nmSm_15Co_85 seed layer. All films were grown in a 130 mT magnetic in-plain field to imprint an in-plane anisotropy. The structure and composition of the films were examined with Rutherford backscattering spectrometry, X-ray reflectivity, and Grazing incidence X-ray diffraction. The magnetic properties of the films were studied with magneto-optic Kerr effect measurement, vibrating sample magnetometer, Kerr microscopy and magnetic force microscopy. The magneto-optic Kerr effect measurement showed that it was possible to change TbCo film's preferred magnetization direction from out-of-plane to in-plane by reducing the film thickness. The SmCo layer made it easier for theTbCo films to change preferred magnetization direction from out-of-plane to in-plane.
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Saci, Abdelhak. "Transport thermique dans les milieux nano-structurés (GaAs)n / (AlAs)n." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2011. http://tel.archives-ouvertes.fr/tel-00825305.
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GaAs et AlAs sont deux bons conducteurs de la chaleur. Or, le matériau artificiel obtenu par empilement de couches nanométriques de ces deux matériaux est un mauvais conducteur. 1 Cet effet remarquable de la nanostructuration est encore mal compris mais deux ingrédients semblent devoir être considérés : 1) la modification profonde des courbes de dispersion des phonons (effet "intrinsèque"), 2) la diffusion des phonons par les défauts localisés aux interfaces (effet "non-intrinsèque"). Il est très difficile de quantifier l'importance relative de ces deux effets. Toutefois, les théories basées uniquement sur les effets intrinsèques ne rendent pas compte de la totalité de la réduction de conductivité observée expérimentalement. Ainsi, le point de vue généralement adopté à ce jour associe le mécanisme dominant à la présence de défauts aux interfaces. Le but de cette thèse est de mieux comprendre les mécanismes de conduction thermique dans les super-réseaux. Pour celà, nous avons étudié expérimentalement l'importance relative des deux effets, intrinsèque et non-intrinsèque, en comparant les propriétés de deux familles d'échantillons, la première présentant des interfaces quasi-parfaites, la seconde présentant des interfaces dégradées. Nous nous sommes intéressés aux super-réseaux (GaAs)n/(AlAs)n. La croissance de ces matériaux est en effet bien maîtrisée et l'accord de maille quasi-parfait entre GaAs et AlAs permet l'élaboration de super-réseaux présentant des interfaces très abruptes. On contrôle alors la qualité des interfaces en ajustant les conditions de croissance. Au delà de l'intérêt fondamental, les études sur les super-réseaux peuvent être utiles à des applications telles que les dispositifs thermoélectriques ou les lasers à semi-conducteurs. Un certain nombre d'études ont montré qu'un super-réseau pouvait avoir une efficacité thermoélec- trique supérieure à celle d'un matériau massif. Or, l'efficacité d'un matériau thermoélectrique augmente lorsque sa conductivité thermique diminue. Il serait alors avantageux de diminuer la conductivité thermique des super-réseaux thermoélectriques. Par contre, les problèmes d'évacuation de chaleur rencontrés dans les lasers utilisant des super-réseaux (puits quantiques) montrent qu'il serait avantageux d'augmenter la conductivité thermique.
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Silva, Maria das Gra?as Dias da. "Efeitos da intera??o dipolar na nuclea??o de v?rtices em nano-cilindros ferromagn?ticos." Universidade Federal do Rio Grande do Norte, 2014. http://repositorio.ufrn.br:8080/jspui/handle/123456789/16635.
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Previous issue date: 2014-07-28Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
The effect of confinement on the magnetic structure of vortices of dipolar coupled ferromagnetic nanoelements is an issue of current interest, not only for academic reasons, but also for the potential impact in a number of promising applications. Most applications, such as nano-oscillators for wireless data transmission, benefit from the possibility of tailoring the vortex core magnetic pattern. We report a theoretical study of vortex nucleation in pairs of coaxial iron and Permalloy cylinders, with diameters ranging from 21nm to 150nm, and 12nm and 21nm thicknesses, separated by a non-magnetic layer. 12nm thick iron and Permalloy isolated (single) cylinders do not hold a vortex, and 21nm isolated cylinders hold a vortex. Our results indicate that one may tailor the magnetic structure of the vortices, and the relative chirality, by selecting the thickness of the non-magnetic spacer and the values of the cylinders diameters and thicknesses. Also, the dipolar interaction may induce vortex formation in pairs of 12nm thick nanocylinders and inhibit the formation of vortices in pairs of 21nm thick nanocylinders. These new phases are formed according to the value of the distance between the cylinderes. Furthermore, we show that the preparation route may control relative chirality and polarity of the vortex pair. For instance: by saturating a pair of Fe 81nm diameter, 21nm thickness cylinders, along the crystalline anisotropy direction, a pair of 36nm core diameter vortices, with same chirality and polarity is prepared. By saturating along the perpendicular direction, one prepares a 30nm diameter core vortex pair, with opposite chirality and opposite polarity. We also present a theoretical discussion of the impact of vortices on the thermal hysteresis of a pair of interface biased elliptical iron nanoelements, separated by an ultrathin nonmagnetic insulating layer. We have found that iron nanoelements exchange coupled to a noncompensated NiO substrate, display thermal hysteresis at room temperature, well below the iron Curie temperature. The thermal hysteresis consists in different sequences of magnetic states in the heating and cooling branches of a thermal loop, and originates in the thermal reduction of the interface field, and on the rearrangements of the magnetic structure at high temperatures, 5 produce by the strong dipolar coupling. The width of the thermal hysteresis varies from 500 K to 100 K for lateral dimensions of 125 nm x 65 nm and 145 nm x 65 nm. We focus on the thermal effects on two particular states: the antiparallel state, which has, at low temperatures, the interface biased nanoelement with the magnetization aligned with the interface field and the second nanoelement aligned opposite to the interface field; and in the parallel state, which has both nanoelements with the magnetization aligned with the interface field at low temperatures. We show that the dipolar interaction leads to enhanced thermal stability of the antiparallel state, and reduces the thermal stability of the parallel state. These states are the key phases in the application of pairs of ferromagnetic nanoelements, separated by a thin insulating layer, for tunneling magnetic memory cells. We have found that for a pair of 125nm x 65nm nanoelements, separated by 1.1nm, and low temperature interface field strength of 5.88kOe, the low temperature state (T = 100K) consists of a pair of nearly parallel buckle-states. This low temperature phase is kept with minor changes up to T= 249 K when the magnetization is reduced to 50% of the low temperature value due to nucleation of a vortex centered around the middle of the free surface nanoelement. By further increasing the temperature, there is another small change in the magnetization due to vortex motion. Apart from minor changes in the vortex position, the high temperature vortex state remains stable, in the cooling branch, down to low temperatures. We note that wide loop thermal hysteresis may pose limits on the design of tunneling magnetic memory cells
Os efeitos de confinamento e o forte acoplamento dipolar na estrutura de v?rtices de nano-elementos ferromagn?ticos ? um tema de interesse atual, n?o apenas pelo valor puramente acad?mico, mas tamb?m pelo impacto em grande n?mero de dispositivos da ?rea de spintr?nica. Muitos dispositivos, como nano-osciladores para transmiss?o de dados sem fio, podem tirar grande proveito da possibilidade de controlar o padr?o magn?tico do n?cleo do v?rtice magn?tico. Relatamos um estudo te?rico da nuclea??o de v?rtices em um par de cilindros coaxiais de ferro e de Permalloy, com di?metros desde 21nm at? 150nm e espessuras de 12nm e de 21nm, separados por uma fina camada n?o-magn?tica. Cilindros isolados de ferro e Permalloy com espessura de 12nm n?o permitem a forma??o de v?rtices, enquanto que cilindros de espessura de 21nm possuem v?rtices quando isolados em reman?ncia. Nossos resultados indicam que ? poss?vel controlar a estrutura magn?tica dos v?rtices, bem como a chiralidade e polaridade relativa dos dois v?rtices, pela escolha apropriada dos valores dos di?metros e da separa??o dos dois cilindros ferromagn?ticos. Dependendo do valor da separa??o entre os cilindros, a intera??o dipolar pode induzir a forma??o de v?rtices em pares de cilindros de espessura de 12nm e inibir a forma??o de v?rtices em pares de cilindros de 21nm de espessura. Al?m disso, mostramos que a rota de prepara??o do estado magn?tico em campo nulo, pode ser usada para determinar a chiralidade e polaridade relativa dos dois v?rtices. Por exemplo: partindo da satura??o da magnetiza??o de um par de cilindros de ferro com di?metro de 81nm e espessura de 21nm, na dire??o do eixo f?cil da anisotropia uniaxial do ferro, resulta um par de v?rtices com n?cleo de 36nm, mesma chiralidade e mesma polaridade. Partindo do estado saturado em uma dire??o no plano e perpendicular ao eixo de anisotropia uniaxial, resulta um par de v?rtices com n?cleo de 30nm de di?metro, com chiralidade e polaridade opostas. Relatamos tamb?m um estudo te?rico do impacto de v?rtices magn?ticos na histerese t?rmica de um par de nanoelementos el?pticos de ferro, de 10nm de espessura, separados por um espa?ador n?o-magn?tico e acoplados com um substrato antiferromagn?tico por energia de 3 troca. Nossos resultados indicam que h? histerese t?rmica em temperatura ambiente (muito menor do que a temperatura de Curie do ferro), se o substrato for uma superf?cie n?o compensada de NiO. A histerese t?rmica consiste na diferen?a da sequ?ncia de estados magn?ticos nos ramos de aquecimento e resfriamento de um ciclo t?rmico, e se origina na redu??o do valor do campo de interface em altas temperaturas, e na reestrutura??o das fases magn?ticas impostas pela intera??o dipolar forte entre os dois nanoelementos de ferro. A largura da histerese t?rmica varia entre 500K ? 100K para dimens?es laterais de 125nm x 65nm e 145nm x 65nm. Focamos nos ciclos t?rmicos de dois estados especiais: o estado antiparalelo, com o nanoelmento em contato com o substrato alinhado na dire??o do campo de interface e o outro nanoelemento alinhado em dire??o oposta; e o estado paralelo em que os dois nanoelementos est?o alinhados com o campo de interface em temperaturas baixas. Esses s?o os dois estados magn?ticos b?sicos de c?lulas de mem?rias magn?ticas de tunelamento. Mostramos que a intera??o dipolar confere estabilidade t?rmica ao estado antiparalelo e reduz a estabilidade t?rmica do estado paralelo. Al?m disso, nossos resultados indicam que um par de cilindros com dimens?es de 125nm x 65nm, separados por 1.1nm, com campo de interface de 5.88kOe em temperatura de 100K, est? no estado paralelo. Essa fase se mant?m at? 249K, quando h? uma redu??o de 50% da magnetiza??o devido ? nuclea??o de um v?rtice no nanoelemento com superf?cie livre. Pequenas varia??es da magnetiza??o, devidas ao movimento do v?rtice, s?o encontradas no ramo de aquecimento, at? 600K. O estado encontrado em 600K se mant?m ao longo do ramo de resfriamento, com pequenas mudan?as na posi??o do v?rtice. A exist?ncia de histerese t?rmica pode ser um s?rio limite de viabilidade de mem?rias magn?ticas de tunelamento
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Saxena, Shubham. "Nanolithography on thin films using heated atomic force microscope cantilevers." Thesis, Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-08302006-223629/.
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Hsieh, Chia-Lung. "Reflection Property of Nano-Acoustic-Waves at Interface." 2004. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2007200417444200.
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Hsieh, Chia-Lung, and 謝佳龍. "Reflection Property of Nano-Acoustic-Waves at Interface." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/24100315642909671011.
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碩士國立臺灣大學
光電工程學研究所
92
In this thesis, we have used optical piezoelectric transducers to generate acoustic waves with nanometer acoustic wavelength and demonstrated the high-resolution surface detection with initiated nano-acoustic waves. The generation and detection of coherent longitudinal-acoustic phonon oscillations were demonstrated in piezoelectric InGaN/GaN multiple quantum wells by pump-probe technique. Due to strong piezoelectric effect in GaN-based system, the coherent phonon oscillations can be treated as a coherent acoustic wave with nanometer acoustic wavelength. Therefore a piezoelectric InGaN/GaN multiple-quantum-wells structure can be regarded as an optical piezoelectric transducer converting electromagnetic energy of femtosecond laser pulses into acoustic energy. The nano-acoustic wave generated by the optical piezoelectric transducer has two promising features: its nanometer-scaled wavelength and its phase information, which is inaccessible to acoustic waves generated by any other mechanism. The initiated nano-acoustic waves were applied to high-resolution surface detection for the first time. The depth resolution reached sub-nanometer which is equal to the most accurate atomic force microscope, one of the most widely used surface detection equipments. Moreover taking advantage of the penetration characteristic of nano-acoustic waves, one can detect the interface pattern inside a solid, which is unreachable for any atomic force microscope. In addition, we demonstrated a novel designed structure of nano-piezoelectric transducer by means of the phase characteristic of reflected nano-acoustic waves. Compared with traditional piezoelectric transducers, this novel transducer structure enhances the acoustic output power. Our study not only provides the design guideline for future nano-piezoelectric-transducers, but also reveals the fact that strain of nano-acoustic wave experiences a 180-degree sign change after total internal reflection at air-solid interface.
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Chen, Bin-Hao, and 陳斌豪. "Molecular Dynamics Modeling on the Nano-Scale Phenomena in Interface Physics." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/70790205378615165727.
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博士國立成功大學
機械工程學系碩博士班
93
The Morse and Morse-like potentials are used to predict the particle interaction of the system. These problems are investigated by the Velocity Verlet Algorithm in the field of molecular dynamics. These works include sputtering phenomenon of early-stage film growth on the interface molecular behavior and Atomic Force Microscope interface phenomena. In thin film growth simulation, the influence of the impact velocity upon the coating parameters is investigated by varying the incident energy of the deposited atoms and substrate geometry. The current results indicate that the re-sputtering is poor when atoms are deposited at low incident energies upon a low temperature substrate. At a higher incident energy and high incident group density, the re-sputtering phenomenon is significant, which results in a topography defect. Furthermore, This study performs molecular dynamics simulations in order to clarify the atomic-scale stick-slip behavior commonly observed when performing surface measurements using an Atomic Force Microscope (AFM). In investigating the surface effects of adhesion, contact deformation, nanoindentation and fracture which occur when a diamond tip interacts with a copper surface, this study considers that both the substrate and the tip deform. The theoretically predicted dynamic behavior of the AFM cantilever tip includes tip oscillation and noise induced by adhesion, nanoindentation and fracture effects. Molecular dynamics simulations are performed to clarify the atomic-scale friction mechanisms associated with surface deformation and to investigate the dynamic behavior of the tip during AFM surface measurement. The relative influences of the adhesion, nanoindentation and fracture effects upon the stick-slip phenomenon are investigated.
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Hughes, Zak E., and T. R. Walsh. "Probing nano-patterned peptide self-organisation at the aqueous graphene interface." 2017. http://hdl.handle.net/10454/15725.
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YesThe peptide sequence GrBP5, IMVTESSDYSSY, is found experimentally to bind to graphene, and ex situ atomic force microscopy indicates the formation of an ordered over-layer on graphite. However, under aqueous conditions neither the molecular conformations of the adsorbed peptide chains, nor the molecular-level spatial ordering of the over-layer, has been directly resolved. Here, we use advanced molecular dynamics simulations of GrBP5, and related mutant sequences, to elucidate the adsorbed structures of both the peptide and the adsorbed peptide over-layer at the aqueous graphene interface. In agreement with a previous hypothesis, we find GrBP5 binds at the aqueous graphene interface chiefly via the tyrosine-rich C-terminal region. Our simulations of the adsorbed peptide over-layers reveal that the peptide chains form an aggregate that does not evolve further into ordered patterns. Instead, we find that the inter-chain interactions are driven by hydrogen bonding and charge–charge interactions that are not sufficiently specific to support pattern formation. Overall, we suggest that the experimentally-observed over-layer pattern may be due to the drying of the sample, and may not be prevalent at the solvated interface. However, our simulations indicate sequence modifications of GrBP5 to promote over-layer ordering under aqueous conditions.
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Liao, Chun-An, and 廖浚安. "Development and application of novel nano-structured thermal interface materials (TIMs)." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/gm666t.
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碩士國立中央大學
機械工程學系
106
This study explored the development of new heterogeneous interface thermal interface materials (TIMs). High-power electronic components generate a large amount of thermal energy during operation, and gaps are formed at the contact surfaces between the electronic components and the heat sink to form a layer of thermal resistance. Therefore, by developing high thermal conductivity TIMs, the gap can be filled to improve the heat conduction performance. The study is divided into two main parts. The first part is to recycle, recycled 2B using ball milling to produce recycled nanoplatelets graphite (Recycled 2B), and then use screen printing technology to use recycled graphene as a highly stretched and low-cost thermal interface. In the second part, the commercially available exfoliated graphite nanoplatelets (EGN) was ball milled to reduce the average particle size, resulting in a high - quality ball-milled exfoliated graphite nanoplatelets (BMEGN). Physical vapor deposition (PVD) is used to develop a novel nano-structure thermal interface material. The through-plane and in-plane thermal conductivity coefficients of the TIMs were measured. Final, the TIMs was actually applied to the temperature measurement of the electronic components.
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Chen, Chiao-Yu, and 陳喬郁. "Isolation of monoclonal antibody with binding activity specific to bio-nano interface." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/829k33.
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碩士國立交通大學
材料科學與工程學系奈米科技碩博士班
104
There are more and more application of nano-materials in medicine and biotechnology. The interest in nano-systems for biological applications is continuously growing. To explore the potential of nano-material in the application of drug delivery, artificial implants, and bio-electronics, the fundamental rules underlining the bio-nano interaction should be carefully investigated. Understanding the bio-nano interface is the key to develop and better use of bionanotechnology. I have demonstrated several specific bio-nano interface previously. I also showed that antibody can recognize gold nanoparticles. Our approach is to develop monoclonal antibody against gold nanoparticles which will serve as the base for further biophysical study and applications. The result indicated that I was able to isolate monoclonal antibody that still maintained the specific binding activity. The single-molecule electrical conductance of the protein transistor made by this antibody revealed the dynamic binding which confirmed the thermodynamics of the binding. Production of monoclonal antibodies consists of four steps: immunizing the animal usually a mouse, obtaining immune cells from the spleen of the immunized mouse, fusing the spleen cells with myeloma cells to obtain hybridomas, and selecting the hybridoma cell line producing the desired monoclonal antibody. I immunized mice using gold nanoparticles. The spleens of positive mice were fused with melanoma. The successful fusion cells were properly dilute and monoclonal antibody was produced. To monitor the binding activity, a special ELISA was designed to distinguish the binding activities of this bio-nano interaction. For example, I was able to assay for different interactions such as the IgG-gold surface, IgG-physical size, and IgG-shape. In addition, the bio-nano interaction was detected by the single-molecule electrical conductance platform, for a final confirmation.
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Sayes, Christie M. "The bio-nano interface: Examining the interactions between water-soluble nanoparticles and cellular systems." Thesis, 2006. http://hdl.handle.net/1911/18969.
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The cytotoxicity of water-soluble and water-suspendable nanoparticles is a sensitive function of their surface derivatization or surface coating, particle size or specific surface area, and crystalline phase (for nanocrystals). In many different human cell lines, the cytotoxicity of a nanomaterial has been shown to change up to 8 orders of magnitude with relatively minor alterations in its structure. Cellular viability was determined through live/dead staining and LDH release. If the nanomaterial was deemed cytotoxic, further biochemical endpoints were tested. In almost all cases, when the nanoparticles were brought into the aqueous phase reactive species were formed. Ex vivo chemiluminescent analysis qualitatively assessed the presence of RS, and evaluated the effect of choice of solvent, suspension agitation, and light exposure. Liquid atomic force microscopy (AFM) was utilized to examine the interaction of nanomaterials with artificial membranes, illustrating the use of in situ AFM to directly observe the interactions of a model nanoparticle with a model cell membrane. By using in vitro, ex vivo, and in situ techniques, this work demonstrates both a strategy for enhancing the toxicity of nanomaterials for certain applications such as cancer therapeutics or bactericides, as well as a remediation for the possible unwarranted biological effects of nanoparticles.
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Hsu, Hao-Chun, and 許皓鈞. "Photo-reactions of the Interface between ITO and Ni-NiO Core-shell Nano-arrays." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/45893325872051004735.
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碩士國立交通大學
材料科學與工程學系所
101
Nanodevice made of one-dimensional nanostructures, such as nanowires, nanobelts or nano-arrays have attracted significant research attentions, because they provide a unique platform for fundamental investigations. The interface plays a critical role in determining the electrical and optoelectronic properties of materials featuring one-dimensional nanostructures. In this work we demonstrate a facile strategy to fabricate a nano-structured device that performes notable photodetecting capabilities. Highly ordered Ni arrays were fabricated using electroless-deposition and an anodic aluminum oxide template. Upon appropriate thermal annealing (350°C). Ni-NiO nano core-shell arrays were formed, where the NiO shell displayed tunable thickness with annealing time. High resolution transmission electron microscopy (HRTEM) demonstrates that the NiO layer with thicknesses of ~ 6nm and 10nm were developed at the Ni arrays’ surfaces at 350°C for 15 minutes and 30minutes annealing, respectively. The Ni/NiO interface naturally formed a Schottky nanojunction, which largely covered arrays’ surfaces. When Ni-NiO nano-arrays were capped with an indium-tin-oxide (ITO) electrode, a ITO/NiO/Ni/Si photo-sensing device was constructed and the device was able to yield phtocurrent when exposed to ultraviolet (UV) light without an external voltage bias and exhibited a broad absorbing range. The photo-reactions and electrical properties of the ITO/NiO/Ni/Si nano-device appeared to strongly depend on NiO thickness and the fabrication details.
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Yeh, Pei-Chuan, and 葉佩娟. "Studying the Nano-Scale Behavior of Diffusion between the Rubbery Polymer into the Glassy Interface." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/57553336565308215621.
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碩士國立清華大學
材料科學工程學系
89
The diffusion in a polymer couple composed of glassy PPO and rubbery PS was explored by using SIMS and AFM to study the polymer chain diffusion across a glassy state interface. The diffusion across the interface was found to follow a typical Case-II diffusion in which the PS chains plasticize the glassy PPO chains in a thin intermixing layer (ca. 20 nm) at the interface. Once the PPO chains diffused out the intermixing layer, they quickly disperse themselves in the PS region forming a completely miscible blend. It was also found that the interface diffusion speed increases with the spin coating speed of the PPO thin film, implying an effect due to chain conformation and the residue stress in the glassy region. In addition, the propagation speed of the diffusion front in the glassy PPO region significantly slowed down in the vicinities of an internal interface created by separate spin coatings. The AFM surface topography of the diffusion couple clearly shows a roughening process associated with the polymer chain diffusion, indicating a nano-scale non-uniform distribution in the lateral directions of the diffusion front.
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Chiu, Chi-cheng. "Conformational study of nano-1 peptide at the water/carbon nanotube interface using molecular dynamics simulations /." 2007. http://proquest.umi.com/pqdweb?did=1441196841&sid=13&Fmt=2&clientId=10361&RQT=309&VName=PQD.
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Chen, Wei-Hao, and 陳威豪. "Impact of Metal/Semiconductor Interface and Surface States on Electrical Properties of Silicon Nano Wire Devices." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/85045326034392908801.
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碩士國立暨南國際大學
電機工程學系
94
A chemical gating CMOS inverter has successfully demonstrated and characterized in this thesis. Nanowire FETs ( NW FETs ), fabricated on silicon-on-insulator wafer, are defined by e-beam lithography. By raising doping concentration and forming TiSi2 in source and drain contact area, we are able to achieve a device with large On/Off current ratio with very high stability. Surface modification carries out by N-(2-Aminoethyl) -3-aminopropyl- trimethoxysilane (AEAPTMS) with concentration of 2.2 mM and gold nanoparticles (gold NPs) solution. The NH2 functional group of AEAPTMS is protonated to NH3+ and acts as a positive gate bias, which makes the threshold voltage (Vth) of the AEAPTMS-modified NW FET shift toward the negative voltage direction. On the contrary, the citrate ions (COO-) adsorbed on the surface of gold NPs and acts as a negative gate bias, which makes the Vth of the gold NPs-modified nanowire FET shift toward the positively. Two NW FETs selectively modified by AEAPTMS and gold NPs were connected in series via Ti/Au electrode. Due to surface modification, two FETs are able to work complementally when gate voltage is in the range from -6 and 6 V. The voltage gain (absolute value of the derivative of VOUT-VIN relation) of the chemical gating CMOS inverter up to 6.67 has been achieved.
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Wu, Linxi. "The impact of nanoconjugation to EGF-induced apoptosis." Thesis, 2016. https://hdl.handle.net/2144/14555.
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Engineered nanoparticles provide potential opportunities for improving current drug delivery, bioimaging and biosensing modalities. In many cases, a ligand, such as a protein, peptide or nucleic acids, is attached to the nanoparticles surface to serve as a targeting group. However, the nanoconjugation (i.e. covalently bound molecules to a nanocarrier) is not an innocuous reaction. It can change the binding affinity and interfere with the intracellular trafficking of the tethered species. The understanding of this influence to the tethered species is still lacking. Therefore, the main objective of this thesis is to investigate the effect of nanoconjugation to the biological identity of the tethered biomolecules, in terms of cellular uptake, intracellular trafficking and the ultimate biological outcomes.
The Epidermal Growth Factor Receptor (EGFR) is a tyrosine kinase that regulates cell proliferation and can cause cancer if dysregulated. Continuous treatment with high doses of EGF can induce apoptosis, in EGFR overexpressing cell lines. In this thesis, Epidermal Growth Factor (EGF) was chosen as the object of investigation. Covalent attachment of EGF to gold nanoparticles (NP-EGF) was found to enhance apoptosis in EGFR overexpressing cell lines (A431, MDA-MB-468) and it is sufficient to induce apoptosis in cell lines exhibiting EGFR expression at physiological levels (HeLa). NP-EGF accumulation through the endosomal pathway was also investigated to assess the impact of nanoconjugation on the spatio-temporal distribution of NP-EGF as potential origin for the observed enhancement of apoptosis. Two orthogonal experimental approaches were applied: (1) isolation of NP-EGF containing endosomes by taking advantage of the increased density of endosomes associated with the uptake of Au NPs; (2) correlated darkfield/fluorescence imaging to map the spatial distribution of NP-EGF in endosomes as a function of time. The studies reveal that nanoconjugation prolongs the dwelling time of phosphorylated receptors in the early endosomes and that the retention of activated EGFR in the early endosomes is accompanied by an EGF mediated apoptosis at effective concentrations that do not induce apoptosis in the case of the free EGF.
Investigating the nanoconjugation-enhanced EGF-induced apoptosis improves the current understanding of cell-nanomatieral interactions and provides new opportunities for overcoming apoptosis evasion by cancer cells.2017-01-01T00:00:00Z
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Cheng, Cheng-Wen, and 鄭程文. "Nano-structure of Mesoporous( Si/MCM-41& Pt/Si/MCM-41)Thin Film and ( GeSi/Ge) Interface." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/42879296637039979329.
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