Literatura académica sobre el tema "Nano-structured Fluids"
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Artículos de revistas sobre el tema "Nano-structured Fluids"
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Gao, Hongfei, Huifang Cheng, Zonghan Yang, Marko Prehm, Xiaohong Cheng y Carsten Tschierske. "Synthesis and self-assembly of 5,5′-bis(phenylethynyl)-2,2′-bithiophene-based bolapolyphiles in triangular and square LC honeycombs". Journal of Materials Chemistry C 3, n.º 6 (2015): 1301–8. http://dx.doi.org/10.1039/c4tc02347a.
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Calderon, Sebastian, Cristiana F. Almeida Alves, Noora K. Manninen, Albano Cavaleiro y Sandra Carvalho. "Electrochemical Corrosion of Nano-Structured Magnetron-Sputtered Coatings". Coatings 9, n.º 10 (20 de octubre de 2019): 682. http://dx.doi.org/10.3390/coatings9100682.
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Magnetron sputtering has been employed for several decades to produce protective and multi-functional coatings, thanks to its versatility and ability to achieve homogeneous layers. Moreover, it is suitable for depositing coatings with very high melting points and that are thermodynamical unstable, which is difficult to accomplish by other techniques. Among these types of coating, transition metal (Me) carbides/nitrides (MeC/N) and amorphous carbon (a-C) films are particularly interesting because of the possibility of tailoring their properties by selecting the correct amount of phase fractions, varying from pure MeN, MeC, MeCN to pure a-C phases. This complex phase mixture can be even enhanced by adding a fourth element such Ag, Pt, W, Ti, Si, etc., allowing the production of materials with a large diversity of properties. The mixture of phases, resulting from the immiscibility of phases, allows increasing the number of applications, since each phase can contribute with a specific property such as hardness, self-lubrication, antibacterial ability, to create a multifunctional material. However, the existence of different phases, their fractions variation, the type of transition metal and/or alloying element, can drastically alter the global electrochemical behaviour of these films, with a strong impact on their stability. Consequently, it is imperative to understand how the main features intrinsic to the production process, as well as induced by Me and/or the alloying element, influence the characteristics and properties of the coatings and how these affect their electrochemical behaviour. Therefore, this review will focus on the fundamental aspects of the electrochemical behaviour of magnetron-sputtered films as well as of the substrate/film assembly. Special emphasis will be given to the influence of simulated body fluids on the electrochemical behaviour of coatings.
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Zeb, Salman, Irshad Ullah, Ali Karim, Wali Muhammad, Naimat Ullah, Mehmand Khan y Warda Komal. "A Review on Nanotechnology Applications in Electric Components". Nanoscale Reports 2, n.º 2 (30 de mayo de 2019): 32–38. http://dx.doi.org/10.26524/nr1924.
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Nano science and nanotechnology innovations have shown incredible results in current era. It increases their applications in various fields such as Engineering, Physics, Chemistry and Biology. The development in nanotechnology has replaced conventional concepts. The remarkable performance of nanotechnologycaught the eye of electrical engineers to make reliable and efficient electrical components. Electrical engineers using Nano-concept and make Nano-structured valueadded products with high superior qualities. This review climaxes the concept of nanotechnology in various electrical components such as in nanowires, insulators, transformers and dielectric fluids with possible future prospects
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Sur, Debashish, Pablo Tirado, Jesus Alcantar, Orlando Auciello y G. Bahar Basim. "Integration of Ultrananocrystalline Diamond (UNCD)-Coatings on Chemical-Mechanical Surface Nano-structured (CMNS) Titanium-Based Dental Implants". MRS Advances 5, n.º 44 (2020): 2261–71. http://dx.doi.org/10.1557/adv.2020.329.
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AbstractThis paper focuses on describing the integration of ultrananocrystalline diamond (UNCD) coating on pure titanium-based dental implants (DIs) integrated with the surface pre-treatment by chemical-mechanical nano-structuring (CMNS) process. The combination of the UNCD coating with the CMNS metal surface treatment provides a transformational process to produce a new generation of metallic implants. CMNS promotes a uniform and dense titanium oxide interface and UNCD enables higher resistance to chemical-induced corrosion by oral fluids and enhanced bone attachment due to superior bone cell growth on C atoms (element of life in human DNA and cell). The main focus of the presented research is to establish the preliminary studies on the integration of the UNCD coating process on CMNS treated dental implants to promote corrosion resistance and biocompatibility. It is demonstrated that the CMNS process in the presence of an oxidizer (1M to be optimal) induces a tailored interface to promote UNCD coating capability through effective interface passivation leading to uniform surface coverage. The final implant product is observed to have improved corrosion potential and enhanced hydrophobicity indicating better biocompatibility providing the basis for a new generation of superior DIs. The findings can further be extended to the hip, knee, and other orthopedic metallic implants, which require major performance improvements, particularly in reducing or eliminating in-vivo body fluid-induced chemical corrosion.
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Voroshylova, N. M., M. D. Timchenko y S. V. Verevka. "Bence-Jones protein as the form of nano-scaled β-stacked supramolecular aggregates". Ukrainian Journal of Nephrology and Dialysis, n.º 1(61) (18 de febrero de 2019): 39–44. http://dx.doi.org/10.31450/ukrjnd.1(61).2019.05.
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Abstract. The formation in β-structured protein aggregates in tissues and fluids of the body is one of the most dangerouse complications of various diseases. The most famous of them are amyloidoses, but they such deposits are observed at other, much more widespread, diseases. The generally accepted approach to amyloids’detectionis based on high-specific coloring by Congo Red dye. However, the Abbe's diffraction limit excludes the seeing of the objects smaller than 0.61 wavelengths (about 240 nm). Such nanoscale formations are capable to disrup the functioning of surrounding tissues, to causethe complications and recurrences of the disease, and to pass through biological barriers with the following accumulation in body’s fluids. It’s likely that these conditions are the cause of the urinary congophilia, that is associated with preeclampsia at pregnancy and chronic kidney disease. Nor the less suspicious object is the Bens-Jones protein that appears in the urine at multiple myeloma and some other diseases, which are in more or less extent,are related to the disturbance of protein metabolism.
The purpose of this study was to clarify the aggregate state of the Bens-Jones protein as a possible β-structured supramolecular associate.
Methods.The subject of the study was the freshly received urine from a patient with multiple myeloma. The presence of the Bens-Jones protein was checked by thermopacification of the acidified sample. For control, the urine was used by a healthy person with the addition of certain amounts of human serum albumin ("Reanal", Hungary) with a concentration of 0, 0.01, 0.1 and 1%.
Result. The obtained data testify to the appropriateness of such a point of view and create preresquites for the expanding of diagnostic possibilities.
Conclusions.The results obtained during the study testify to the peculiarity of the structure of the Bens-Jones protein, which is nano-sized beta-structured supramolecular
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Sarafraz, M. M., F. Hormozi y S. M. Peyghambarzadeh. "Pool boiling heat transfer to aqueous alumina nano-fluids on the plain and concentric circular micro-structured (CCM) surfaces". Experimental Thermal and Fluid Science 72 (abril de 2016): 125–39. http://dx.doi.org/10.1016/j.expthermflusci.2015.11.001.
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Cardea, Stefano. "Using a 3-Steps Supercritical Fluids Assisted Process for the Generation of Nanostructured Biopolymeric Scaffolds". Recent Innovations in Chemical Engineering (Formerly Recent Patents on Chemical Engineering) 12, n.º 1 (25 de junio de 2019): 7–14. http://dx.doi.org/10.2174/2405520412666181126145617.
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Background: Scaffolds can be used to substitute the extracellular matrix and to favour the generation of tissues and organs. Until now, various processes have been implemented for scaffolds generation, but they are characterized by several limits. Methods: In this work, we tested a supercritical fluids assisted process for the generation of nano-structured biopolymeric scaffolds; it is characterized by three steps: generation of a polymeric gel (loaded with a porogen), drying of the gel using supercritical CO2, waterwashing to remove the porogen. Results: 3D Poly(D,L-lactic acid) scaffolds have been obtained, characterized by very high porosity (> 90%) and surface are (> 200 m2/g), and by a fibrous nanostructure (fibres ranging between 60 and 400 nm) superimposed to a micrometric cellular structure. Conclusion: Moreover, suitable mechanical properties (up to 125 KPa) and very low solvents residue (< 5 ppm) have been obtained.
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Tahir, Wajiha, S. Bilal, Nabeela Kousar, Imtiaz Ali Shah y Ali S. Alqahtani. "Analysis about enhancement in thermal characteristics of viscous fluid flow with induction of ferrite particles by using Cattaneo Christov theory". Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 236, n.º 1 (1 de octubre de 2021): 208–18. http://dx.doi.org/10.1177/09544062211042653.
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The elevated convective heat transfer process plays vital role in performance of electronic and engineering equipment’s. Over the years various attempts have been executed in this regards, including the insertion of nano elements in poorly conducting liquids. Initially, improvement in thermophysical characteristics of ordinary fluids was observed but with advancement in nanoparticles structuring new classifications in nano elements are found. Among these discoveries experimentations have explored highly fascinating and intrinsically featured class of nanomaterials renowned as ferromagnetic nano constituents. So, the motivation regarding this investigation is execution about change in thermal features of base liquid with insertion of different ferrite particles. Here, water is considered as based liquid and Nickel Zinc Ferrite (NiZnFe2O4) and magnetite ferrite (Fe2O4) as solid particles are inserted. Impact of magnetic dipole is also envisioned to produce optimized effectiveness of ferrite particles. Energy transmission in flow domain is depicted by incorporation of Cattaneo-Christov heat flux model. Mathematical formulation containing thermo mechanical features of ferrite particles are attained in complexly structured partial differential system and afterwards similarity transformations are implemented for transmutation into ODES. Constructed problem is simulated by implementing numerical approaches. Influence of involved variables on associated distributions are displayed through graphs and tables. It is demonstrated that momentum as well as heat transfer of base fluid augments with inclusion of Nickel Zinc ferrite as compared magnetite ferrite. It is inferred that velocity shows declining behavior against Curie temperature whereas reverse behavior is seen for temperature profile. It is divulged that viscous dissipation imparts diminishing impact on momentum whereas contrary behavior is depicted in case of temperature profile. In addition, increment in wall drag magnitude and thermal flux is manipulated by incorporation of (NiZnFe2O4) rather than (Fe2O4).
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Sztucki, Michael, Manfred Burghammer, Oleg Konovalov, Edward Mitchell y Theyencheri Narayanan. "Synchrotron X-ray Scattering techniques for soft matter industrial research and development". Acta Crystallographica Section A Foundations and Advances 70, a1 (5 de agosto de 2014): C1329. http://dx.doi.org/10.1107/s2053273314086707.
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Consumer products based on soft matter technology often exhibit macroscopic properties which are strongly dependent on their micro- and nano-structures extending over multiple size scales. Synchrotron scattering techniques are ideally suited for probing these multilevel structures and deliver complementary and in some cases unique information as compared to real space methods like confocal microscopy, cryo-electron microscopy or atomic force microscopy. The European Synchrotron Radiation Facility (ESRF) is a world-leading synchrotron light source which operates several state-of-the-art instruments for the investigation of soft materials and offers expertise to academic and industrial users. Fast and flexible access for proprietary experiments with a modular, fine-tuned service is guaranteed. A range of dedicated sample environments which mimic industrial processing conditions are available. This presentation will illustrate the state-of-the-art performance of the following synchrotron scattering techniques by recent examples of industrial relevance. Simultaneous small and wide angle X-ray scattering (SAXS/WAXS) is a powerful method to determine the microstructure and phase behavior of multi-component systems like detergents, food products, pharmaceutical components, polymer composites, etc. The high photon flux translates to high throughput measurements, while the high degree of collimation and resolution permit to elucidate a wide range of length scales from a few Angstroms up to micron scale. Scanning microbeam SAXS/WAXS and single micro-crystal/fiber diffraction (µXRD) allows elucidating the local nanostructure of very small objects like micro-specimens of composite organic/inorganic materials, teeth, bones, micromechanical parts, polymer fibers, micro fluidics, etc. with micro/nanometric real space resolution. X-ray reflectivity (XR) and grazing incidence diffraction/scattering (GID /GISAXS) can reveal the nanoscale structure and complexity of nano-structured complex fluids at interfaces, organic films, biological membranes, etc.
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Wang, Xiao Jian, Jian Yu Xiong, Yun Cang Li, Peter D. Hodgson y Cui E. Wen. "Apatite Formation on Nano-Structured Titanium and Niobium Surface". Materials Science Forum 614 (marzo de 2009): 85–92. http://dx.doi.org/10.4028/www.scientific.net/msf.614.85.
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Current orthopaedic biomaterials research mainly focuses on developing implants that could induce controlled, guided and rapid healing. In the present study, the surface morphologies of titanium (Ti) and niobium (Nb) metals were tailored to form nanoporous, nanoplate and nanofibre-like structures through adjustment of the temperature in the alkali treatment. The in vitro bioactivity of these structures was then evaluated by soaking in simulated body fluid (SBF). It was found that the morphology of the modified surface significantly influenced the apatite inducing ability. The Ti surface with a nanofiber-like structure showed better apatite inducing ability, than the nanoporous or nanoplate surface structures. A thick dense apatite layer formed on the Ti surface with nanofiber-like structure after 1 week soaking in SBF. It is expected that the nanofibre-like surface could achieve good apatite formation in vivo and subsequently enhance osteoblast cell adhesion and bone formation in vivo.
Tesis sobre el tema "Nano-structured Fluids"
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Hu, Ben. "Nano-structured and surface polymerized magnetorheological fluid /". abstract and full text PDF (free order & download UNR users only), 2005. http://0-wwwlib.umi.com.innopac.library.unr.edu/dissertations/fullcit/3209226.
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Thesis (Ph. D.)--University of Nevada, Reno, 2005."December 2005." Includes bibliographical references (leaves 155-166). Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2005]. 1 microfilm reel ; 35 mm.
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Yang, Xiaofan. "Multi-scale simulation of filtered flow and species transport with nano-structured material". Diss., Manhattan, Kan. : Kansas State University, 2010. http://hdl.handle.net/2097/4271.
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Mastrangelo, Rosangela. "A new class of hydrogels: PVA-based Twin-Chain Networks for the cleaning of Modern and Contemporary Art". Doctoral thesis, 2021. http://hdl.handle.net/2158/1235963.
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Untypical artistic techniques, fleeting materials and tridimensional surfaces make the artworks of the last century impermanent and delicate, if compared to traditional, flat easel paintings. As a result, the cleaning of Modern and Contemporary paintings is a very delicate process: the removal of dirt or grime deposited on their surface can be challenging. Traditional cleaning techniques were found to be unsuitable for this purpose: free solvents spread on the surface and swell the paint layers, water-based fluids can leach the paint components, while confining systems like traditional gels are too rigid, and/or leave residues on the surface.
Poly(vinyl alcohol) (PVA)-based cryogels can meet the demand for new, science-driven, materials for restoration. This class of hydrogels, obtained through a freeze-thawing (FT) process, exhibits unique properties, such as high water retentiveness, free water content and adaptability to rough surfaces, interconnected porosity, structural cohesion and ease of handling/removal. Cryogels can be loaded with cleaning fluids, or just be swollen in water, and then placed in contact with the surface to clean: the free water inside the network allows the detaching of dirt, that is eventually trapped in the polymer matrix.
The characteristics of PVA cryogels can be tailored by adding a second polymer that acts as a semi-interpenetrating agent, and/or varying the number of FT cycles. The chemical nature of polymer chains, and their molecular weight, also affect the final gel structure. As a result, the gel porosity, the rheological behavior and the dynamics of polymer chains embedded in the network are expected to change.
Twin-Chain Polymer Networks (TC-PNs) were obtained by mixing two PVAs with higher (H-PVA) and lower (L-PVA) molecular weight and hydrolysis degree. Despite the very similar structure of the two polymers, a liquid-liquid phase separation occurred in the pre-gel solution: L-PVA chains are expelled from the H-PVA continuous phase and form spherical blobs, which act as porogens during cryostructuration. Confocal and Scanning Electron Microscopies revealed the sponge-like structure of TC-PNs, with micron-sized and interconnected pores. Small Angle X-ray Scattering and Differential Scanning Calorimetry clarified details about the structure at the nanoscale, while Fluorescence Correlation Spectroscopy (FCS) revealed the polymers dynamics. On the other hand, rheology data suggested that the semi-interpenetrating polymers can alter the gelation process, acting also as structuring agents.
The diffusion of cleaning nano-structured fluids (NSFs) through the gels matrix was investigated through FCS: polymer-surfactant interactions and gels porosity were proven to influence the diffusive components.
Overall, TC-PNs exhibited unprecedented cleaning performances, unconceivable with traditional methods. TC-PNs were successfully used to treat two Jackson Pollock’s and one Pablo Picasso’s masterpieces (Peggy Guggenheim collection, Venice), bringing back the paints original hue and brightness.
Capítulos de libros sobre el tema "Nano-structured Fluids"
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Binetruy, Christophe, Francisco Chinesta y Roland Keunings. "Complex Flows of Micro/Nano Structured Fluids: Reinforced Polymer Composites". En Flows in Polymers, Reinforced Polymers and Composites, 43–108. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-16757-2_2.
Texto completoActas de conferencias sobre el tema "Nano-structured Fluids"
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McLeod, Logan S., Levent F. Degertekin y Andrei G. Fedorov. "Grain Boundary Diffusion of Hydrogen in Nano-Structured Pd/Ag Alloy Membranes". En ASME 2008 3rd Energy Nanotechnology International Conference collocated with the Heat Transfer, Fluids Engineering, and Energy Sustainability Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/enic2008-53014.
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Palladium and its alloys have long been used as hydrogen separation membranes due to their extremely high permeability and selectivity to hydrogen over all other gases [1]. The hydrogen permeation process begins with selective chemisorption of the gas onto the metal surface. As the adsorption process is the point in the permeation sequence where the majority of gases become excluded, it follows that a cleverly designed device could be created to take advantage of the so-called ‘fast’ diffusion paths of surface and grain-boundary diffusion to further enhance permeability without sacrificing selectivity. The contribution of grain-boundary diffusion to the overall permeation rate is dependent on the relative volume in the membrane occupied by grain-boundaries versus bulk material. Typically, grain boundaries only make up a miniscule fraction of the overall volume and therefore only contribute an appreciable amount to the overall diffusion process at temperatures low enough to make the bulk diffusion process nearly stagnant. However, in the case of a nanostructured membrane this paradigm is no longer valid. The fabrication methods associated with extremely thin membrane deposition typically lead to highly non-equilibrium microstructure with an average grain size on the order of tens of nanometers [2]. In order to exploit the potential advantages of grain boundary diffusion the nano-scale grains must persist throughout operation. To avoid the tendency for the grain structure to relax to a more equiaxed, coarse-grained morphology the self-diffusion of metal atoms in the film must be minimized by operating the membranes at a temperature much lower than the membrane melting temperature. Figure 1 shows the microstructural changes in a thin, sputtered, Pd/Ag alloy film before and after annealing. The initial fine-grained structure on the bottom surface of the membrane is due to a combination of low substrate temperature during deposition and the Ti adhesion layer onto which the Pd/Ag layer was deposited. After annealing at 400 C the grains have coarsened and the top and bottom structure are identical.
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Chiu, W. K. S., A. V. Virkar, K. L. Reifsnider, F. Rabbi y Q. Liu. "HeteroFoaMs: Electrode Modeling in Nano-Structured Heterogeneous Materials for Energy Systems". En ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology collocated with ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/fuelcell2011-54950.
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Heterogeneous Functional Materials, e.g., “HeteroFoaMs” are at the heart of countless energy systems, including (from left to right below) heat storage materials (a), batteries (b), solid oxide fuel cells (c), and polymer electrolyte fuel cells (d). HeteroFoaMs are generally nano-structured and porous to accommodate transport of gasses or fluids, and must be multi-functional (i.e., active operators on mass, momentum, energy or charge, in combinations). This paper will discuss several aspects of modeling the relationships between the constituents and microstructure of these material systems and their device functionalities. Technical advances based on these relationships will also be identified and discussed. Three major elements of the general problem of how to model HeteroFoaM electrodes will be addressed. Modeling approaches for ionic charge transfer with electrochemistry in the nano-structured porosity of the electrode will be discussed. Second, the effect of morphology and space charge on conduction through porous doped ceria particle assemblies, and their role in electrode processes will be modeled and described. And third, the effect of local heterogeneity and morphology on charge distributions and polarization in porous dielectric electrode materials will be analyzed using multi-physics field equations set on the details of local morphology. Several new analysis methods and results, as well as experimental data relating to these approaches will be presented. The value, capabilities, and limitations of the approaches will be evaluated.
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Kim, Seol Ha, Ho Seon Ahn, Joonwon Kim y Moo Hwan Kim. "Dynamics of a Water Droplet on the Heated Surface of Nano- and Micro-Structures". En ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icnmm2012-73316.
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In this study, we investigated the dynamic behavior of a water droplet near the Leidenfrost point (LFP) of bare and modified zirconium alloy surfaces with bundles of nanotubes (∼10–100 nm) or micro mountain-like structures using high-speed photography. A deionized water droplet (6 μL) was dropped onto the sample surfaces (20 × 25 × 0.7 mm) that were heated to temperatures ranging from 250°C to the LFP. The modified zirconium alloy surfaces showed complete wetting and well-spread features at room temperature due to strong liquid spreading by the structure. The meniscus of the liquid droplet on the structured surface experienced more vigorous dynamics with intensive nucleate boiling, compared with the clean, bare surface. The cutback phenomenon was observed on the bare surface; however, the structured surfaces showed a water droplet “burst”. We observed that the LFPs were 449°C, 522°C, and 570°C, corresponding to the bare, micro-, and nano-structures, respectively.
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Zhao, X., Z. Chen, X. Liu y C. Ding. "Preparation, Microstructure and Bioactivity of Plasma-Sprayed TiO2 Coating". En ITSC2007, editado por B. R. Marple, M. M. Hyland, Y. C. Lau, C. J. Li, R. S. Lima y G. Montavon. ASM International, 2007. http://dx.doi.org/10.31399/asm.cp.itsc2007p0397.
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Abstract In this paper, nano-structured TiO2 coatings have been successfully deposited onto titanium alloy substrates by atmospheric plasma spraying technology using optimized plasma parameters. A chemical treatment method was employed to induce bioactivity on the TiO2 surface. The bioactivity of as-sprayed and chemical treated TiO2 coatings were evaluated by investigating the formation of apatite on their surface after they were soaked in simulated body fluids (SBF) for a period of time. Microstructure and the phase composition of the as-sprayed coating and apatite were analyzed by Field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectrometry (EDS). The results obtained indicate that as-sprayed TiO2 coating consists of rutile, anatase and suboxide such as Ti3O5. The surface of nano-TiO2 coating is covered by nano particles of about 50nm in size. The bonding strength of TiO2 coating with Ti alloy substrate is as high as 40 MPa. The corrosion resistance performance of nano-coating in SBF is better than that of Ti-6Al-4V alloy. The surface of as-sprayed TiO2 coating can not induce bone-like apatite formation. Chemical treatment, such as acid and alkali, can improve bioactivity of TiO2 coating surface.
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Demko, Michael T., Stephen R. Hostler y Alexis R. Abramson. "The Numerical Mirage Method for Photothermal Characterization of Materials". En ASME 2008 Heat Transfer Summer Conference collocated with the Fluids Engineering, Energy Sustainability, and 3rd Energy Nanotechnology Conferences. ASMEDC, 2008. http://dx.doi.org/10.1115/ht2008-56468.
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Photothermal measurements are increasingly attractive for thermal analysis of fragile nano-structured materials or as an in situ measurement for investigation of coupled thermal and mechanical properties. The most common thermal property measurements, including the laser flash and photothermal reflectance methods, have limited applicability due to stringent requirements on geometry, thermal, and optical properties of the material. In contrast, the mirage method typically does not require any sample modification and places a minimum number of restrictions on the sample geometry. This method uses a periodically modulated pump laser to heat a sample material and a probe beam to observe the resulting change in index of refraction of a gas above the sample. In this work, the experimental methodology and data analysis are generalized to allow more accurate measurement of low thermal diffusivity materials. The method expands upon the work of Ravi et al. (2002), but alternatively uses a numerical solution to the heat equations, more accurately capturing a square-wave heat application from the pump laser and non-zero probe beam height.
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Yang, Qingzhen, Ben Q. Li y Yucheng Ding. "Electrohydrodynamic Patterning of Micro/Nano-Structures on Thin Polymer Films". En ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64471.
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Electrohydrodynamic (EHD) patterning provides an alternative to fabricate the controllable polymeric micro/nano-structures, which have wide applications in industry. Both steady state and dynamic development of EHD patterning structures are discussed in this paper. For the steady state modeling, a discontinuous boundary element coupled with finite element method is applied. Numerical results reveal that a critical voltage exists, below which a small amplitude structure is obtained and above which polymer evolves into patterns with a large height/width ratio. The transient process of EHD patterning is represented by the numerical solution of the phase field equation coupled with the electric field and Navier-Stokes equation. The computer model is capable of describing the dynamic development of the electrically-induced transport and surface deformation phenomena during EHD patterning. The coupled multi-field equations are discretized in finite difference with an enhancement by parallel computing. For structured templates, the application of an electric field creates the conformal structures in the polymer film with the periodicity and aspect ratios of the polymer structures controlled by template patterns and applied electric fields. Analysis indicates that the interaction between the applied field and the fluids leads to an occurrence of complex flow structures and free surface deformation and plays an important role in determining the dynamics of an EHD patterning process.
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Chen, Min, Bing-Yang Cao y Zeng-Yuan Guo. "Micro/Nano-Scale Fluid Flows on Structured Surfaces". En ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62023.
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Understanding the effects of surface nanostructures on fluid flow in micro- and nano-channels is highly desirable for micro/nano-electro-mechanical systems. By way of equilibrium and non-equilibrium molecular dynamics simulations, wetting on nano-structured surfaces and liquid flow in nano-channels with structured surfaces are simulated. The surfaces show dual effects on the boundary slip and friction of the liquid flow in nano-channels. Generally, the nanostructures enhance the surface hydrophilicity for a hydrophilic liquid-solid interaction, and increase the hydrophobicity for a hydrophobic interaction. Simultaneously, the nanostructures distort the nanoscale streamlines of the liquid flow near the channel surface and block the flow, which decreases the apparent slip length. The twofold effects of the nanostructures on the surface wettability and the hydrodynamic disturbance result in a non-monotonic dependence of the slip length on the structure’s size. However, the surface structure may lead to a very high contact angle of about 170° in some cases, which cause the surface show super-hydrophobicity and lead to a remarkable velocity slip. The surface nanostructures can thus be applied to control the friction of micro- and nano-flows. In addition, the gaseous flows in micro- and nano-channels with structured surfaces are simulated. The geometry of the surface is modeled by triangular, rectangular, sinusoidal and randomly triangular nanostructures respectively. The results show that the velocity slips, including negative slip, depend not only on the Knudsen number but also the surface structure. The impacts of the surface nanostructure and the gas rarefaction are strongly coupled. In general, the slip length of a gaseous flow over a structured surface is less than what predicted by the Maxwell model, and depends not only on the Knudsen number but also the size of the surface nanostructures.
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Sriraman, S. R. y D. Banerjee. "Pool Boiling Studies on Nano-Structured Surfaces". En ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42581.
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The effect of nano-structures on pool boiling heat transfer is explored in this study. The silicon nano-structures are fabricated on 4″ double-side polished silicon wafers using Step and Flash Imprint Lithography (SFIL) process. An array of “nano-fins” consisting of 200 nm diameter pillars of 100 nm height, lateral pitch of 1 μm and transverse pitch of 0.9 μm are created in a rectangular pattern on the wafer surface. The test surface is used for pool boiling experiments using PF-5060 as the test fluid (Manufacturer - 3M Co., boiling point - 56 °C). Experiments are performed under saturation and liquid sub-cooling conditions. The heat flux measurements on the nanostructures are compared with that of bare surfaces. The test rig is of constant heat flux type. Results are reported at the maximum heat flux point. The nano-structured test surface showed a 41% increase in heat flux compared to the bare test surface under the saturation test condition. The 10-degree sub-cooling and 20-degree sub-cooling test conditions showed a 19% and 27% enhancement at the maximum heat flux point respectively.
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Kunkle, Claire M. y Van P. Carey. "Metrics for Quantifying Surface Wetting Effects on Vaporization Processes at Nanostructured Hydrophilic Surfaces". En ASME 2016 Heat Transfer Summer Conference collocated with the ASME 2016 Fluids Engineering Division Summer Meeting and the ASME 2016 14th International Conference on Nanochannels, Microchannels, and Minichannels. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/ht2016-7203.
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A static contact angle is most often used as a means of quantifying the wetting characteristics of the liquid phase in vaporization processes at a solid surface. This metric is often convenient to measure and intuitive in its interpretation, but when a surface is superhydrophilic, the resulting low contact angles are difficult to measure accurately from photographs of sessile droplet profiles or contact line regions. For droplets at ultra low contact angles, small changes of contact angle can produce very large changes in wetted surface area, which makes small uncertainties in contact angle result in large uncertainties in wetted area. For hydrophilic nanostructured surfaces, another disadvantage is that the relationship of the macroscopic (apparent) contact angle to the nanoscale interaction of the liquid and vapor contact line with the nanostructured surface is not always clear. In this study, a new wetting metric based on spreading characteristics of sessile droplets is proposed that can be easily measured for hydrophilic surfaces. This metric also has the advantage that it is a more direct and sensitive indicator of how a droplet spreads on the surface. The spread area directly impacts heat transfer interactions between the droplet and the surface, therefore affecting evaporation time. Consequently, a metric that more directly illustrates the spread area provides an indication of how the wetting will affect these mechanisms. Use of the proposed new metric is explored in the context of evaporation and boiling applications with superhydrophilic surfaces. Characteristics of this metric are also compared to static contact angle and other choices of wetting metrics suggested in earlier studies, such as dynamic advancing and receding contact angles, and spreading coefficients. The effects of nanoscale structure and/or roughness on the proposed wetting metric are analyzed in detail. A model is developed that predicts the dependence of the proposed wetting parameter on intrinsic material wettability for rough, nano-structured surfaces. The model results demonstrate that the proposed metric is a more sensitive indicator of macroscopic wetting behavior than apparent contact angle when the surface is superhydrophilic. This characteristic of the proposed new metric is shown to have advantages over other wetting metrics in the specific case of superhydrophilic nanostructured surfaces. Application of the proposed wetting metric is demonstrated for some example nanostructured surfaces. The results of our study indicate that this proposed new metric can be particularly useful for characterizing the effects of variable wetting on vaporization processes on highly wetted nanostructured surfaces.
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Hao, Tingting, Huiwen Yu, Xuehu Ma y Zhong Lan. "Heat Transfer Characteristics of Horizontal Nano-Structured Oscillating Heat Pipes". En ASME 2019 6th International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/mnhmt2019-4100.
Texto completoResumen
Abstract Working fluid in the oscillating heat pipe (OHP) with low turn number (< 9) positioned in the horizontal heat mode could not easily backflow to the evaporator due to the absence of gravity. In this paper, copper OHP with superhydrophilic nano-structured inner surface by introducing additional capillary force was investigated through the visualization and thermal experiments. OHPs with 6 turns, charged with pure water as the working fluid, were fabricated with copper, and nano-structured inner surface and tested for comparison. Contact angles of water on the copper and superhydrophilic surface were 36.7 and 0 deg. The filling ratio of water was 50%, 65%, and 80%, respectively. Startup performance, thermal resistance, and liquid slug oscillation of OHPs were investigated experimentally at the heat input of 100–380 W. Experimental results showed that OHPs with the superhydrophilic nano-structured surface showed an enhanced heat transfer performance due to the nanostructure-induced capillary action for water in the horizontal direction. The optimum filling ratio was 65% in this work. Dryout was observed in the OHPs with the filling ratio of 50% at the heat input higher than 220 W. At the filling ratio of 80%, the working fluid was accumulated in the adiabatic and condensation section, and the driving force due to the water evaporation in evaporator was not high enough to activate the movements of liquid slugs. Heat transfer performance of OHP with nano-structured surface was higher than that of bare copper surface by introducing the additional capillary force.