Academic literature on the topic 'Nanofluidlcs'
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Journal articles on the topic "Nanofluidlcs"
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Murshed, S. M. Sohel. "Nanofluids and Nanofluidics." Nanomaterials 12, no. 17 (August 24, 2022): 2914. http://dx.doi.org/10.3390/nano12172914.
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Lin, Jianzhong, Mingzhou Yu, Martin Seipenbusch, Xiaoke Ku, and Yu Feng. "Nanofluidics and Nanofluids." Journal of Nanotechnology 2019 (May 2, 2019): 1–2. http://dx.doi.org/10.1155/2019/8767624.
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Le, Thu, Hisashi Shimizu, and Kyojiro Morikawa. "Advances in Label-Free Detections for Nanofluidic Analytical Devices." Micromachines 11, no. 10 (September 23, 2020): 885. http://dx.doi.org/10.3390/mi11100885.
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Nanofluidics, a discipline of science and engineering of fluids confined to structures at the 1–1000 nm scale, has experienced significant growth over the past decade. Nanofluidics have offered fascinating platforms for chemical and biological analyses by exploiting the unique characteristics of liquids and molecules confined in nanospaces; however, the difficulty to detect molecules in extremely small spaces hampers the practical applications of nanofluidic devices. Laser-induced fluorescence microscopy with single-molecule sensitivity has been so far a major detection method in nanofluidics, but issues arising from labeling and photobleaching limit its application. Recently, numerous label-free detection methods have been developed to identify and determine the number of molecules, as well as provide chemical, conformational, and kinetic information of molecules. This review focuses on label-free detection techniques designed for nanofluidics; these techniques are divided into two groups: optical and electrical/electrochemical detection methods. In this review, we discuss on the developed nanofluidic device architectures, elucidate the mechanisms by which the utilization of nanofluidics in manipulating molecules and controlling light–matter interactions enhances the capabilities of biological and chemical analyses, and highlight new research directions in the field of detections in nanofluidics.
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Lei, Lei. "Testing algorithm for heat transfer performance of nanofluid-filled heat pipe based on neural network." Open Physics 18, no. 1 (November 13, 2020): 751–60. http://dx.doi.org/10.1515/phys-2020-0170.
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AbstractTraditional testing algorithm based on pattern matching is impossible to effectively analyze the heat transfer performance of heat pipes filled with different concentrations of nanofluids, so the testing algorithm for heat transfer performance of a nanofluidic heat pipe based on neural network is proposed. Nanofluids are obtained by weighing, preparing, stirring, standing and shaking using dichotomy. Based on this, the heat transfer performance analysis model of the nanofluidic heat pipe based on artificial neural network is constructed, which is applied to the analysis of heat transfer performance of nanofluidic heat pipes to achieve accurate analysis. The experimental results show that the proposed algorithm can effectively analyze the heat transfer performance of heat pipes under different concentrations of nanofluids, and the heat transfer performance of heat pipes is best when the volume fraction of nanofluids is 0.15%.
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Esfe, Mohammad Hemmat, Somchai Wongwises, Saeed Esfandeh, and Ali Alirezaie. "Development of a New Correlation and Post Processing of Heat Transfer Coefficient and Pressure Drop of Functionalized COOH MWCNT Nanofluid by Artificial Neural Network." Current Nanoscience 14, no. 2 (February 1, 2018): 104–12. http://dx.doi.org/10.2174/1573413713666170913122649.
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Background: Because of nanofluids applications in improvement of heat transfer rate in heating and cooling systems, many researchers have conducted various experiments to investigate nanofluid's characteristics more accurate. Thermal conductivity, electrical conductivity, and heat transfer are examples of these characteristics. Method: This paper presents a modeling and validation method of heat transfer coefficient and pressure drop of functionalized aqueous COOH MWCNT nanofluids by artificial neural network and proposing a new correlation. In the current experiment, the ANN input data has included the volume fraction and the Reynolds number and heat transfer coefficient and pressure drop considered as ANN outputs. Results: Comparing modeling results with proposed correlation proves that the empirical correlation is not able to accurately predict the experimental output results, and this is performed with a lot more accuracy by the neural network. The regression coefficient of neural network outputs was equal to 99.94% and 99.84%, respectively, for the data of relative heat transfer coefficient and relative pressure drop. The regression coefficient for the provided equation was also equal to 97.02% and 77.90%, respectively, for these two parameters, which indicates this equation operates much less precisely than the neural network. Conclusion: So, relative heat transfer coefficient and pressure drop of nanofluids can also be modeled and estimated by the neural network, in addition to the modeling of nanofluid’s thermal conductivity and viscosity executed by different scholars via neural networks.
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Chen, Xueye. "Molecular dynamics simulation of nanofluidics." Reviews in Chemical Engineering 34, no. 6 (November 27, 2018): 875–85. http://dx.doi.org/10.1515/revce-2016-0060.
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Abstract This review reports the progress on the recent development of molecular dynamics simulation of nanofluidics. Molecular dynamics simulations of nanofluidics in nanochannel structure, surface roughness of nanochannel, carbon nanotubes, electrically charged, thermal transport in nanochannels and gases in nanochannels are illustrated and discussed. This paper will provide an expedient and valuable reference to designers who intend to research molecular dynamics simulation of nanofluidic devices.
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Han, W. S., and S. H. Rhi. "Thermal characteristics of grooved heat pipe with hybrid nanofluids." Thermal Science 15, no. 1 (2011): 195–206. http://dx.doi.org/10.2298/tsci100209056h.
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In the present study, the specially designed grooved heat pipe charged with nanofluids was investigated in terms of various parameters such as heat transfer rate(50-300 W with 50 W interval), volume concentration(0.005%, 0.05%, 0.1%, and hybrid combinations), inclination(5?, 45?, 90?), cooling water temperature (1?C, 10?C, and 20?C), surface state, transient state and so on. Hybrid nanofluids with different volume concentration ratios with Ag-H2O and Al2O3-H2O were used as working fluids on a grooved heat pipe(GHP). Comparing with the pure water system, nanofluidic and hybrid nanofluidic system shows greater overall thermal resistance with increasing nano-particle concentration. Also hybrid nanofluids make the system deteriorate in terms of thermal resistance. The post nanofluid experimental data regarding GHP show that the heat transfer performance is similar to the results of nanofluid system. The thermal performance of a grooved heat pipe with nanofluids and hybrid nanofluids were varied with driving parameters but they led to worse system performance.
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Iyahraja, S., J. Selwin Rajadurai, M. Sivakumar, and N. N. Lenin. "Investigation on silver-water nanofluid for development of new viscosity correlation." Bulletin of the Chemical Society of Ethiopia 37, no. 2 (December 14, 2022): 505–14. http://dx.doi.org/10.4314/bcse.v37i2.18.
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ABSTRACT. The present study addresses an experimental investigation on the influence of the concentration of nanoparticles and temperature on nanofluid's viscosity and establishes a numerical correlation for predicting the nanofluid's viscosity. In this study, silver nanoparticles (Ag) with a size of 20 nm were used to prepare the nanofluid with water as the base fluid. The concentrations of silver nanoparticles were fixed as 0.01, 0.05, and 0.1% by volume in the range of temperature from 20 to 60oC. The findings of the current investigations report that the nanofluid's viscosity increases with volume fractions of nanoparticles and decreases as the temperature increases. The theoretical correlations in the literature under predict the viscosity of silver-water nanofluids, which has led to the development of a new relationship for determining the nanofluids' effective viscosity from the experimental findings of this research. The proposed model as outcome of the current investigation confirms a reasonable agreement with the experimental data.
KEY WORDS: Silver nanoparticles, Nanofluid, Viscosity, Volume Concentration, Temperature
Bull. Chem. Soc. Ethiop. 2023, 37(2), 505-514.
DOI: https://dx.doi.org/10.4314/bcse.v37i2.18
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Wohld, Jake, Joshua Beck, Kallie Inman, Michael Palmer, Marcus Cummings, Ryan Fulmer, and Saeid Vafaei. "Hybrid Nanofluid Thermal Conductivity and Optimization: Original Approach and Background." Nanomaterials 12, no. 16 (August 18, 2022): 2847. http://dx.doi.org/10.3390/nano12162847.
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The focus of this paper was to develop a comprehensive nanofluid thermal conductivity model that can be applied to nanofluids with any number of distinct nanoparticles for a given base fluid, concentration, temperature, particle material, and particle diameter. For the first time, this model permits a direct analytical comparison between nanofluids with a different number of distinct nanoparticles. It was observed that the model’s average error was ~5.289% when compared with independent experimental data for hybrid nanofluids, which is lower than the average error of the best preexisting hybrid nanofluid model. Additionally, the effects of the operating temperature and nanoparticle concentration on the thermal conductivity and viscosity of nanofluids were investigated theoretically and experimentally. It was found that optimization of the operating conditions and characteristics of nanofluids is crucial to maximize the heat transfer coefficient in nanofluidics and microfluidics. Furthermore, the existing theoretical models to predict nanofluid thermal conductivity were discussed based on the main mechanisms of energy transfer, including Effective Medium Theory, Brownian motion, the nanolayer, aggregation, Molecular Dynamics simulations, and enhancement in hybrid nanofluids. The advantage and disadvantage of each model, as well as the level of accuracy of each model, were examined using independent experimental data.
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Ouyang, Wei, Jongyoon Han, and Wei Wang. "Nanofluidic crystals: nanofluidics in a close-packed nanoparticle array." Lab on a Chip 17, no. 18 (2017): 3006–25. http://dx.doi.org/10.1039/c7lc00588a.
Full textDissertations / Theses on the topic "Nanofluidlcs"
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Cabral, Francismara Pires. "Estudo da ebulição convectiva de nanofluidos no interior de microcanais." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/18/18147/tde-16092013-163829/.
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Este trabalho trata do estudo teórico do ebulição convectiva de nanofluidos em canais de diâmetro reduzido (denominados de microcanais). Ele aborda, primeiramente, uma análise da literatura sobre a ebulição convectiva de fluidos convencionais em microcanais, na qual são discutidos critérios para a transição entre macro e microcanais e os padrões de escoamentos observados em canais de reduzido diâmetro. Métodos para a previsão das propriedades de transporte de nanofluidos foram levantados da literatura e estudos experimentais da convecção forçada, da ebulição nucleada e da ebulição convectiva de nanofluidos foram discutidos. Um método para a previsão do coeficiente de transferência de calor de nanofluidos em microcanais durante a ebulição convectiva foi proposto baseado em modelos convencionais da literatura ajustados para nanofluidos. O ajuste dos modelos convencionais foi realizado através de análise regressiva de dados experimentais para ebulição nucleada e convecção forçada de nanofluidos levantados da literatura, e da análise crítica de adimensionais que capturassem a influência das nanopartículas no processo de transferência de calor. De maneira geral o método proposto neste estudo apresenta concordância razoável com dados experimentais independentes, referente ao acréscimo do coeficiente de transferência de calor com o incremento da concentração volumétrica de nanopartículas. No entanto, a escassez de estudos experimentais sobre a ebulição convectiva de nanofluidos, especialmente em microcanais, impossibilitou uma análise mais aprofundada do método proposto.The present work aims the theoretical study of convective boiling of nanofluids in small diameter channels (called microchannel). It discusses an analysis of the literature on convective boiling of conventional fluids in microchannels which presents criteria for the transition between conventional and microchannels and the flow patterns observed in small diameter channels. Methods for predicting the transport properties of nanofluids were compiled from the literature and experimental studies of forced convection, nucleate boiling and convective boiling of nanofluids were discussed. A method for predicting the heat transfer coefficient of nanofluids in microchannels during convective boiling was proposed based on conventional models from literature adjusted to nanofluids. The conventional models fitting was performed by regression analysis of experimental data for nucleate boiling and forced convection of nanofluids compiled from the literature and by critical analysis of dimensionless numbers which enable to capture the influence of nanoparticles on heat transfer process. In general the proposed method in this work presents reasonable agreement with independent experimental data regarding the increase in heat transfer coefficient with increasing nanoparticles volume fraction. However the scarcity of experimental studies on the convective boiling of nanofluids, especially in microchannels, precluded further analysis of the proposed method.
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Rueda, García Daniel. "Development of novel electroactive nanofluids for flow cells." Doctoral thesis, Universitat de Barcelona, 2020. http://hdl.handle.net/10803/670918.
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Flow cells are on their way to become a key player for electrical energy storage (EES) thanks to their suitability as load-levelling devices thus contributing to the development of smart grid and to offset the intermittency of renewable energy sources. Until recently flow cells have been limited to Redox Flow Batteries (RFB), where energy storage is given by the redox reactions of dissolved ions. Very recently, new types of “flowable” electrodes have been proposed making use of capacitive storage mechanism (Electrochemical Flow Capacitors or EFCs). Our group has been one of the pioneering labs in this type of novel flow cells based on electroactive nanofluids. The present thesis aimed at harnessing the activity of well-known electroactive species (quinones, graphene, polyoxometalates, LiFePO4) in novel electroactive nanofluids. An important part of our strategy has been the design of hybrid formulations and systems which could combine faradaic (redox) and capacitive (double-layer) storage mechanisms in order to improve the performance of the resulting flow cells.
We make an extended review and perspective of the electrochemical flow cell technology and their possible lines of evolution in the introduction of this thesis. With this we introduce the state of the art, the issues to solve and the different solutions proposed. Moreover, we also show our point of view and prospective for this technology and electrical energy storage in general.
In the chapter 4, the electrochemical fundamentals of quinones in lithium-organic electrolytes are studied. Quinones electrochemical mechanisms have been widely studied in aqueous media. In this work we study them in an organic electrolyte in an attempt to take advantage of the greater solubility and wider potential windows available in this media. We found and describe in detail several issues preventing the reversible functioning of quinones in Li+ organic electrolytes which in turn preclude their use in flow cells under those conditions.
Chapter 5 describes the synthesis, characterization and electrochemical performance of hybrid materials based on reduced graphene oxide (rGO) and polyoxometalates dispersed in an aqueous H2SO4 electrolyte in order to produce a nanofluid. These nanofluids feature low viscosity and show an ultrafast electrochemical
response. We demonstrated their functioning as energy storage fluids with full charge and discharge of all solid material dispersed.
In chapter 6 a new kind of rGO nanofluid is presented. Instead of using conventional surfactants, we dissolved an aromatic molecule able to stabilize rGO in an aqueous electrolyte. With this approach we achieved a great increase in the stability of the nanofluid. Furthermore, this new nanofluid also showed a great charge transfer capability, as demonstrated by its enabling of the redox activity of LiFePO4 nanoparticles. Thus, thanks to the presence of rGO in the nanofluid, electrons could reach the dispersed nanoparticles and thus be effectively and fully charged and discharged, something not possible in nanofluids containing only LiFePO4 nanoparticles.
Graphene synthesis has been also deeply studied as part of this thesis as is shown in the chapter 7. As a result, a new method for the production of graphene by electrochemical exfoliation of graphite has been developed and patented. The patent, a summary of the results obtained and the state of the art of the electrochemical exfoliation method of graphene are presented in this thesis as the last chapter describing research work carried out within the framework of this thesis.Las celdas de flujo van camino de convertirse en una pieza clave para el almacenamiento de energía eléctrica (EES) gracias a su idoneidad como dispositivos de nivelación de carga, contribuyendo así al desarrollo de una red inteligente que pueda compensar la intermitencia de las fuentes de energía renovables. Hasta hace poco, las celdas de flujo se habían limitado a las baterías de flujo redox (RFB), donde el almacenamiento de energía está dado por las reacciones redox de los iones disueltos. Muy recientemente, se han propuesto nuevos tipos de electrodos líquidos basados en un mecanismo de almacenamiento capacitivo (condensadores de flujo electroquímicos o EFC). Nuestro grupo ha sido uno de los laboratorios pioneros en este tipo de nuevas celdas de flujo basadas en nanofluidos electroactivos. La presente Tesis ha tenido como objetivo aprovechar la actividad de especies electroactivas bien conocidas (quinonas, grafeno, polioxometalatos, LiFePO4) en nuevos nanofluidos electroactivos. Una parte importante de nuestra estrategia ha sido el diseño de formulaciones y sistemas híbridos que pudieran combinar mecanismos de almacenamiento faradaico (redox) y capacitivo (doble capa) para mejorar el rendimiento de las celdas de flujo resultantes. En la introducción de esta tesis se ha realizado una revisión y perspectiva ampliadas de las tecnologías de celdas de flujo electroquímicas y sus posibles líneas de evolución. Con esto se presentan el estado del arte, los problemas a resolver y las diferentes soluciones propuestas para estas tecnologías. Además, también mostramos nuestro punto de vista y perspectivas para estas tecnologías y el almacenamiento de energía eléctrica en general. Por ello esta parte constituye la parte principal de la introducción y una parte fundamental de esta tesis para entender los objetivos, motivaciones y el trabajo realizado. En el capítulo 4 se estudiaron los fundamentos electroquímicos de las quinonas en electrolitos orgánicos con sal de litio. Los mecanismos electroquímicos de las quinonas se han descrito ampliamente en la bibliografía pero en medios acuosos. En este trabajo, los estudiamos en un electrolito orgánico en un intento de aprovechar la mayor solubilidad y las ventanas de potencial más amplias disponibles en este medio. Encontramos y describimos en detalle varios problemas que impiden el funcionamiento reversible de las quinonas en los electrolitos orgánicos con Li+ que, a su vez, impiden su uso en celdas de flujo en esas condiciones. En el capítulo 5 se describe la síntesis, caracterización y rendimiento electroquímico de materiales híbridos basados en óxido de grafeno reducido (rGO) y polioxometalatos dispersos en un electrolito acuoso (H2SO4) para producir un nanofluido. Estos nanofluidos presentan baja viscosidad y muestran una respuesta electroquímica ultrarrápida e hibrida, con contribución tanto capacitiva del rGO como faradaica de los polioxometalatos. Demostrando así su funcionamiento como fluidos de almacenamiento de energía con plena carga y descarga de todo el material sólido disperso. El sexto capítulo presenta un nuevo tipo de nanofluido basado en rGO. En lugar de usar tensioactivos convencionales como en el capítulo descrito anteriormente, disolvimos una molécula aromática capaz de estabilizar el rGO en un electrolito acuoso mediante interacciones de tipo π-π. Con este enfoque logramos un gran aumento en la estabilidad del nanofluido. Además, este nuevo nanofluido también mostró una gran capacidad de transferencia de carga, como lo demuestra el hecho de que permite que se produzca actividad redox de nanopartículas de LiFePO4 (sin recubrimento conductor) simplemente dispersas en el nanofluido. Por lo tanto, gracias a la presencia de rGO en el nanofluido, los electrones podrían alcanzar las nanopartículas dispersas y, por lo tanto, cargarse y descargarse de manera efectiva y completa, algo que no es posible en nanofluidos que contienen solo nanopartículas de LiFePO4. La síntesis de grafeno también se ha estudiado en profundidad en esta tesis tal y como se puede ver en el capítulo 7, dado que el objetivo final es producir materiales que se puedan usar en aplicaciones reales, asegurarse de que los materiales con los que se trabaja se pueden producir en cantidades grandes, mediante métodos escalables y elementos abundantes es también importante. Como resultado, se ha desarrollado y patentado un nuevo método para la producción de grafeno por exfoliación electroquímica de grafito. En esta tesis se presenta la patente, un resumen de los resultados obtenidos y el estado del arte del método de exfoliación electroquímica de grafeno. En esta tesis hemos demostrado el potencial de los nanofluidos en el almacenamiento de energía electroquímica. A partir de los resultados mostrados aquí, podemos inducir conclusiones generales importantes sobre los efectos extendidos de pequeñas cantidades de sólidos en todo el volumen del nanofluido. Hemos demostrado que las dispersiones estables de rGO en agua pueden transferir la carga a través de todo el volumen de nanofluidos, lo que hace que todo el nanofluido actúe como un electrodo supercondensador que almacena la carga a través de un mecanismo capacitivo. De hecho, el nanofluido acuoso rGO mostró una transferencia de carga extremadamente rápida, pudiendo realizar ciclos a 10V·s-1. Gracias a esta rápida transferencia de carga, pudimos cargar y descargar por completo nanopartículas activas redox dispersas de LiFePO4 y detectar claramente picos redox incluso a 25 mV·s-1. Además, al dopar el rGO con especies redox activas moleculares como los polioxometalatos, desarrollamos sistemas híbridos con potencia y capacidad mejoradas con respecto al nanofluido rGO puro. Finalmente, demostramos que los nanofluidos de rGO acuosos pueden mejorar su estabilidad al disolver una molécula aromática (DABA) capaz de estabilizar rGO mediante interacciones π-π manteniendo su buena conductividad eléctrica. Todo esto ha sido posible manteniendo la viscosidad de los nanofluidos desarrollados muy cerca de los disolventes originales, lo que facilitará su aplicación final en dispositivos de flujo real. Por otro lado, la baja concentración de nanopartículas de grafeno podría ser una desventaja para la aplicación de estos materiales en dispositivos de alta densidad de energía. Por lo tanto, aumentar la carga de nanopartículas electroactivas es un objetivo importante. En resumen, hemos diseñado y preparado nanofluidos basados en grafeno pero también en híbridos de grafeno. Hemos mostrado en esta descripción general cómo estos novedosos materiales de nanofluidos pueden presentar rendimientos sobresalientes incluso en el caso de sistemas muy diluidos. Hemos demostrado efectos no lineales, que conducen a propiedades notables con pequeñas cantidades de grafeno dispersas en los nanofluidos. Por lo tanto, nuestro trabajo subraya el sólido potencial de estos sistemas para el almacenamiento de energía.
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Rodríguez-Laguna, María del Rocío. "Heat transfer fluids: From fundamental aspects of graphene nanofluids at room temperature to molten salts formulations for solar-thermal conversion." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667803.
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Los fluidos de transferencia de calor, y en particular los nanofluidos, se pueden considerar un elemento esencial en diversos sectores industriales y su rendimiento es clave para una adecuada aplicación en tecnologías que van desde la gestión térmica y la refrigeración, a la generación de energía solar térmica y eléctrica mediante el uso de intercambiadores de calor. Estas industrias necesitan fluidos de transferencia de calor con un rango de temperatura del líquido más amplio y mejores prestaciones en la transferencia de calor que los fluidos convencionales. Todos los fluidos parecen beneficiarse de la dispersión de nanopartículas sólidas, tanto aquellos usados en aplicaciones de baja temperatura y temperatura ambiente, como aquellos que funden a más alta temperatura (p. ej. sales fundidas). La dispersión de nanopartículas conduce a la obtención de nanofluidos que con frecuencia presentan mejores conductividades térmicas y/o calores específicos en comparación con los fluidos base. Sin embargo hay algunas excepciones. En la bibliografía podemos encontrar resultados contradictorios acerca de la mejora de las propiedades térmicas en nanofluidos, lo cual hace que sea necesario un estudio de estos materiales en mayor profundidad. Por otra parte, la naturaleza líquida de estos materiales plantea un verdadero desafío, tanto desde el punto de vista experimental como en relación al marco conceptual.
El trabajo que se presenta en esta tesis ha abordado dos retos diferentes relacionados con los fluidos de transferencia de calor y los nanofluidos. En primer lugar, se llevó a cabo un estudio riguroso y sistemático de las propiedades térmicas, morfológicas, reológicas, de estabilidad, acústicas y vibracionales de nanofluidos de grafeno en disolventes orgánicos. Observamos un gran aumento de la conductividad térmica de hasta un 48% y un aumento del 18% en la capacidad calorífica de los nanofluidos de grafeno en N,N-dimetilacetamida (DMAc). También se observó una mejora significativa en los nanofluidos de grafeno en N,N-dimetilformamida (DMF) del orden del 25% y 12% para la conductividad térmica y la capacidad calorífica, respectivamente. El desplazamiento de varias bandas del espectro Raman de DMF y DMAc hacia altas frecuencias (máx. ~ 4 cm-1) al aumentar la concentración de grafeno, sugirió que éste tiene la capacidad de afectar a las moléculas de disolvente a larga distancia, en términos de energía vibracional. En paralelo, las simulaciones numéricas basadas en la teoría funcional de la densidad (DFT) y dinámica molecular (MD) mostraron una orientación paralela de DMF hacia el grafeno, favoreciendo la interacción π-π y contribuyendo a la modificación de los espectros de Raman. Además, se observó un orden local de las moléculas de DMF alrededor del grafeno, lo que sugiere que tanto este tipo especial de interacción como el orden local inducido pueden contribuir a la mejora de las propiedades térmicas del fluido. También se realizaron estudios similares en nanofluidos de grafeno disperso en 1-metil-2-pirrolidona, sin embargo, no se observó ninguna modificación de la conductividad térmica o de los espectros de Raman. Todas estas observaciones juntas sugieren que existe una correlación entre la modificación de los espectros vibracionales y el aumento de la conductividad térmica de los nanofluidos. En vista de los resultados, se discutieron y descartaron algunos de los mecanismos propuestos para explicar la mejora de la conductividad térmica en nanofluidos.
La segunda línea de investigación se centró en el desarrollo y caracterización de nuevas formulaciones de sales fundidas con baja temperatura de fusión y alta estabilidad térmica. Con este propósito, se sintetizaron dos nuevas formulaciones de seis componentes basadas en nitratos con una temperatura de fusión de 60-75 °C y una estabilidad térmica de aprox. 500 °C. Por otro lado, la complejidad de las muestras llevó a establecer una serie de métodos experimentales que se proponen para la detección del punto de fusión de estos materiales como una alternativa a la calorimetría convencional, estas técnicas son: espectroscopia Raman, técnica 3ω y transmisión óptica.Heat transfer fluids and nanofluids constitute an important element in the industry and their performance is key to the successful application in technologies that go from heat management and cooling to heat exchangers in thermal-solar energy and electricity generation. These industries demand heat transfer fluids with a wider liquid temperature range and better thermal performance than the conventional fluids. From low-temperature fluids to high-temperature molten salts, these fluids seem to benefit from the dispersion of solid nanoparticles, leading to nanofluids which frequently feature improved thermal conductivities and/or specific heats as compared with the bare fluids. However, there are some exceptions. Contradictory reports make it necessary to study these materials in greater depth than has been usual. Yet, the liquid nature of these materials poses a real challenge, both from the experimental point of view and from the conceptual framework. The work reported in this thesis has tackled two different challenges related to heat transfer fluids and nanofluids. In the first place, a careful and systematic study of thermal, morphological, rheological, stability, acoustic and vibrational properties of graphene-based nanofluids was carried out. We observed a huge increase of up to 48% in thermal conductivity and 18% in heat capacity of graphene-N,N-dimethylacetamide (DMAc) nanofluids. A significant enhancement was also observed in graphene-N,N-dimethylformamide (DMF) nanofluids of approximately 25% and 12% for thermal conductivity and heat capacity, respectively. The blue shift of several Raman bands (max. ~ 4 cm-1) with increasing graphene concentration in DMF and DMAc nanofluids suggested that graphene has the ability to affect solvent molecules at long-range, in terms of vibrational energy. In parallel, numerical simulations based on density functional theory (DFT) and molecular dynamics (MD) showed a parallel orientation of DMF towards graphene, favoring π–π stacking and contributing to the modification of the Raman spectra. Furthermore, a local order of DMF molecules around graphene was observed suggesting that both this special kind of interaction and the induced local order may contribute to the enhancement of the thermal properties of the fluid. Similar studies were also performed in graphene-N-methyl-2-pyrrolidinone nanofluids, however, no modification of the thermal conductivity or the Raman spectra was observed. All these observations together suggest that there is a correlation between the modification of the vibrational spectra and the increase in the thermal conductivity of the nanofluids. In light of these results, the mechanisms suggested in the literature to explain the enhancement of thermal conductivity in nanofluids were discussed and some of them were discarded. The second line of research focused on the development and characterization of novel molten salts formulations with low-melting temperature and high thermal stability. In this regard, two novel formulations of six components based on nitrates with a melting temperature of 60-75 °C and a thermal stability up to ~ 500 °C were synthesized. Moreover, the complexity of the samples led to establish a series of experimental methods which are proposed for the melting temperature detection of these materials as an alternative to conventional calorimetry. These methods are Raman spectroscopy, three-omega technique, and optical transmission.
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Meng, Huaiyu. "CMOS nanofluidics." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/120374.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 217-226).
Diagnostic tests are essential to medical practice. In vitro diagnostics is a market worth US$ 40-45 billion. Diagnostic tests are usually conducted in centralized laboratories, equipped with expensive instrumentation and staffed with trained personnel. An important part of clinical diagnosis involves protein and DNA sensing. Significant effort is made to make protein and DNA sensing more accessible and affordable, through micro and nano-technologies. However, typical commercial and academic devices for molecular sensing suffered needs for external equipment, high cost and large form factors. In this work, we propose a self-contained point-of-care platform based on complementary metal oxide semiconductor (CMOS). CMOS platform has the capability of pattern features at the scale of nanometers. Important electronic functions in bio-sensing, such as amplifiers, counters and drivers are routinely implemented in CMOS. With the introduction of photonic and nanofluidic functionalities in this thesis, a CMOS chip can potentially perform biomolecular sensing without the aid of external equipment, hence becoming true lab-on-chip devices. This thesis presents the methods developed to introduce nanofluidic and photonic devices in commercial CMOS chips. We first introduce a method to fabricate nanofluidic channels in CMOS by using the transistor gate polysilicon as a sacrificial layer. A nanochannel with critical dimension of 100nm and length of 200 [mu]m is fabricated. Actuation and separation of bio-molecules in the nanochannel with electrophoresis is demonstrated. We then incorporate avalanche photodiodes (APD) in CMOS. Additionally, a packaging method is introduced to work with CMOS chips with size of a few square millimeters. With components mentioned above, clinical applications, such as gene mapping for virus identification and protein separation for cancer diagnosis and monitoring, could potentially run on a chip without external equipment.
by Huaiyu Meng.
Ph. D.
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Blancafort, Jorquera Miquel. "Theoretical reaction and relaxation dynamics in superfluid helium nanodroplets." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668116.
Full textAbstract:
The study of superfluid helium has been carried out mainly by physicists. In recent years, taking advantage of the potentialities presented by superfluid helium nanodroplets (HeNDs) as inert matrices at very low temperatures (0.37 K), the chemical community became involved in its application to high-resolution spectroscopy. More recently (early 2000s), this community began to be involved in research using HeNDs to investigate chemical reactivity in this quantum solvent. As for the theoretical studies on the dynamics of physicochemical processes in HeNDs, they have been possible about five years ago and the number of theoretical dynamics studies, despite their interest, is very scarce. The main objective of this thesis is to contribute to the development of the research in this area.
To introduce the reader into the topic, Chapter 1 is divided into four sections: the first one describes the properties of helium, the second one considers the history of the discovery and research carried out on the superfluidity phenomenon, the third one outlines the properties of superfluid helium nanodroplets, and the last one gives an overview of the applications and fields of study implying HeNDs.
The theoretical and numerical methods used to describe superfluid liquid helium are detailed in Chapter 2. In the first section attention has been paid on the density functional theory (DFT) and its time dependent extension for real-time simulations (TDDFT). The second section describes the main density functionals used and the third section is aimed to present the numerical methods employed to perform the TDDFT calculations.
The following four chapters contain the original studies carried out in this thesis. The investigation of the capture process of a Ne atom by a HeND can be found in Chapter 3. Here, the atom is treated using classical mechanics and the influence of energy and angular momentum is examined for a wide set of initial conditions. The microscopic mechanism, energy and angular momentum exchanges and vortex formation have been extensively analysed. The present contribution corresponds to the first systematic analysis of the influence of angular momentum in the capture process and vortex formation.
Chapter 4 represents a natural evolution from Chapter 3 and describes the formation of a neon dimer or neon adduct inside a superfluid helium nanodroplet, treating both atoms classically. Analogously as in the previous chapter, angular momentum has also been taken into consideration and the mechanism, energy an angular momentum exchanges and vortex formation are analysed. These two chapters complement and extend two previous investigations of our group where the Ne atoms were treated using standard quantum mechanics at zero angular momentum. The contents of Chapter 4 correspond to the second theoretical investigation on bimolecular reaction dynamics in HeNDs.
The following two chapters use a full quantum hybrid approach to explore rotational and vibrational energy relaxation dynamics. Chapter 5 corresponds to the first theoretical study reported so far on the rotational energy relaxation dynamics of molecules in HeNDs. This process has been studied using several isotopes of the H2 molecule (fast rotors) and considering a set of initial excitations and nanodroplet sizes.
The last investigation (Chapter 6) is centred on the study of the vibrational energy relaxation in HeNDs. Thus, the influence of the energy gap between the vibrational levels, molecule-helium interaction energy and nanodroplet size on the vibrational relaxation dynamics has been analysed, taking as a reference the I2@(4He)100 doped nanodroplet which was recently studied in our group. To the best of our knowledge it is the first time that the influence of these key factors has been examined.
Finally, in Chapters 7 and 8 the main conclusions and a summary in Catalan are presented.Les nanogotes d’heli superfluid (HeNDs) són matrius inerts i nanoreactors ideals a baixa temperatura (0.37 K). Això ha atret l’atenció de químics doncs permeten realitzar espectroscopia d’altra resolució, estudiar la reactivitat i sintetitzar en condicions especials. L’estudi teòric de la dinàmica de processos en HeND ha estat possible tan sols fa cinc anys i, tot i el seu interès, n’hi ha molt pocs estudis. L’objectiu d’aquesta tesi és contribuir a la recerca en aquesta àrea. El Capítol 1 descriu les propietats de l’heli, la història de la superfluïdesa i les propietats i aplicacions de les HeNDs. La teoria del funcional de la densitat (DFT) i l’extensió de la mateixa depenent del temps (TDDFT), els principals funcionals per HeNDs i els mètodes numèrics es presenten al Capítol 2. Els següents capítols contenen els estudis originals d’aquesta tesi. En el Capítol 3 s’investiga la captura de Ne en una HeND on l’àtom es tracta clàssicament. El mecanisme, els intercanvis d’energia i moment angular i la formació de vòrtexs s’han analitzat àmpliament. Aquest és el primer anàlisi rigorós de la influència del moment angular en la captura i formació de vòrtexs. El Capítol 4 descriu la formació de Ne2/Ne-Ne en HeND tractant ambdós àtoms clàssicament. El mecanisme, bescanvis d’energia i moment angular i formació de vòrtexs també s’han estudiat. És el segon estudi sobre reaccions bimoleculars en HeNDs. Els Capítols 3 i 4 complementen i amplien dues investigacions del nostre grup on els àtoms es van tractar quànticament amb moment angular zero. En els propers dos capítols es consideren les relaxacions rotacional i vibracional utilitzant enfocs quàntics híbrids. El Capítol 5 correspon al primer estudi teòric de la relaxació rotacional de molècules en HeNDs, i s’han considerat varis isòtops de H2 i excitacions inicials i mides de nanogota. El Capítol 6 detalla la influència de la separació energètica vibracional, interacció molècula-heli i mida de nanogota en la relaxació vibracional en HeNDs, agafant com a referència el sistema I2@(4He)100. És el primer cop que s’examina l’efecte d’aquestes propietats clau. Els Capítols 7 i 8 presenten les principals conclusions i un resum en català, respectivament.
Las nanogotas de helio superfluido (HeNDs) son matrices inertes y nanoreactores ideales a baja temperatura (0.37 K). Esto ha atraído a los químicos pues posibilitan realizar espectroscopia de alta resolución, así como estudiar de la reactividad y síntesis en condiciones especiales. La dinámica teórica de procesos en HeND ha sido posible tan sólo hace cinco años y, a pesar de su interés, todavía hay muy pocos estudios. Esta tesis pretende contribuir a la investigación en esta área. El Capítulo 1 describe las propiedades del helio, la superfluidez y las propiedades y aplicaciones de las HeNDs. La teoría del funcional de la densidad (DFT) y su extensión dependiente del tiempo (TDDFT), los principales funcionales para HeNDs y los métodos numéricos se presentan en el Capítulo 2. Los siguientes capítulos contienen los estudios originales de esta tesis. En el Capítulo 3 se investiga la captura de Ne en una HeND donde el átomo se trata clásicamente. El mecanismo microscópico, intercambios de energía y momento angular y formación de vórtices se han analizado ampliamente. Este es el primer análisis detallado de la influencia del momento angular en la captura y la formación de vórtices. El Capítulo 4 describe la formación de Ne2/Ne-Ne en HeND tratando ambos átomos clásicamente. El mecanismo, intercambios de energía y momento angular y formación de vórtices también se han estudiado. Los Capítulos 3 y 4 complementan y amplían dos investigaciones de nuestro grupo donde los átomos se trataron cuánticamente con momento angular cero. En los dos capítulos siguientes se estudian las relajaciones rotacional y vibracional utilizando enfoques cuánticos híbridos. El Capítulo 5 corresponde al primer estudio teórico de la relajación rotacional de moléculas en HeNDs, y se han considerando varios isótopos de H2, excitaciones iniciales y tamaños de nanogota. El Capítulo 6 detalla la influencia de la separación energética, interacción molécula-helio y tamaño de nanogota en la relajación vibracional en HeND, habiéndose tomando como referencia el sistema I2@(4He)100. Es la primera vez que se examina el efecto de estas propiedades clave en la dinámica. Los Capítulos 7 y 8 presentan las principales conclusiones y un resumen en catalán, respectivamente.
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Hamze, Samah. "Graphene based nanofluids : development, characterization and application for heat and energy systems." Thesis, Rennes 1, 2020. http://www.theses.fr/2020REN1S010.
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Dans notre vie quotidienne, le transfert de la chaleur et de l’énergie constitue la base de nombreux processus industriels. L’épuisement progressif des énergies fossiles conduit à améliorer et optimiser les rendements de ces échanges par de nouveaux procédés. Pour cela, une idée d’améliorer la performance thermique des fluides dans les échangeurs de chaleur a été proposée pour réduire l’énergie consommée pour l’échange de chaleur. Cette idée est basée sur l’introduction des nanoparticules solides qui présentent des propriétés thermiques beaucoup plus importantes que les liquides caloporteurs dans ces derniers, en obtenant un nanofluide. Cette introduction a pour effet d’augmenter la conductivité thermique du fluide mais d’autre part provoque une augmentation défavorable de sa viscosité qui résulte en une augmentation de la puissance de pompage. Alors il faut faire un compromis entre la stabilité, la conductivité thermique et la viscosité des nanofluides. Dans cette étude, des nanofluides à base de graphène à quelques couches et un fluide commercial, Tyfocor® LS, ont été préparés dans la gamme de concentration massique 0,05-0,5% en utilisant trois surfactants différents. Une étude complète sur ces nanofluides est présentée, y compris la synthèse des feuillets de graphène, la préparation des nanofluides et l’étude de leur stabilité, ainsi que l’évaluation expérimentale de leurs propriétés thermophysiques en fonction de la concentration en graphène, du type de surfactant utilisé et de la température dans la gamme 283,15-323,15 K. Finalement, sur la base de ces résultats et par une approche qualitative, le potentiel applicatif des nanofluides dans des systèmes énergétiques est déterminé pour sélectionner le meilleur candidat. Les résultats ont montré une bonne amélioration de la performance thermique par rapport aux fluides de base dans la gamme de température testée et surtout le nanofluide de la série du surfactant Pluronic® P-123 de concentration massique 0,25%In our daily lives, the heat and energy transfer forms the basis of many industrial processes. The gradual depletion of fossil fuels leads to improving and optimizing the efficiency of these exchanges through new processes. To this end, the idea of improving the thermal performance of fluids in heat exchangers has been proposed forward to reduce the energy consumed for heat exchange. This idea is based on the introduction of solid nanoparticles, which have much greater thermal properties than heat-transfer fluids in the latter, obtaining a nanofluid. This introduction has the effect of increasing the thermal conductivity of the fluid but on the other hand causes an unfavorable increase in its viscosity, which results in an increase in pumping power. So a compromise has to be made between the stability, thermal conductivity and viscosity of nanofluids. In this study, few layer graphene based nanofluids and a commercial fluid, Tyfocor® LS, were prepared in the weight concentration range 0.05-0.5% using three different surfactants. A complete study on these nanofluids is presented, including the synthesis of the graphene sheets, the preparation of the nanofluids and the study of their stability, as well as the experimental evaluation of their thermo-physical properties as a function of the graphene concentration, the type of surfactant used and the temperature in the range 283.15-323.15 K. Finally, on the basis of these results and through a qualitative approach, the potential application of nanofluids in energy systems is determined in order to select the best candidate. The results showed a good improvement of the thermal performance compared to the base fluids in the tested temperature range and especially the nanofluid of the Pluronic® P-123 surfactant series with a mass concentration of 0.25%
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Gravelle, Simon. "Nanofluidics : a theoretical and numerical investigation of fluid transport in nanochannels." Thesis, Lyon 1, 2015. http://www.theses.fr/2015LYO10238.
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Cette thèse décrit diverses situations liées au transport fluidique aux nano-échelles. Le premier chapitre est une introduction à la nanofluidique qui contient une revue des longueurs caractéristiques, des forces et des phénomènes présents aux nano-échelles. Le deuxième chapitre est une étude de l'impact de la géométrie sur la perméabilité hydrodynamique d'un nanopore. Inspirée par la forme des aquaporines, cette étude suggère une optimisation possible pour des canaux biconiques. Le troisième chapitre est une étude du remplissage capillaire dans des canaux sub-nanométriques en carbone. Cette étude montre l'importance de la pression de disjonction induite par la structure du fluide sur le remplissage. Le quatrième chapitre est une étude d'une diode nanofluidique, un composant connu pour imiter le comportement d'une diode à semi-conducteur. On montre qu'un fort couplage entre l'eau et la dynamique des ions entraîne une rectification du flux d'eau à l'intérieur de la diode. Le cinquième et dernier chapitre est une étude de l'origine du bruit rose (1=f) communément observé lors des mesures de courant ionique dans les nanoporesThis thesis discusses various situations linked to transport at the nanoscale. The first chapter is an introduction to nanofluidics, containing a review of characteristic lengths, forces, or phenomena existing at the nanoscale. The second chapter is a study of the impact of geometry on the hydrodynamic permeability of a nanopore. This study, inspired by the shape of aquaporins, suggests a possible optimisation of permeability for bi-conical channels. The third chapter is a study of capillary filing inside subnanometric carbon channels which highlights the importance of the disjoining pressure induced by the fluid structuring inside the nanochannel. The fourth chapter is a study of nanofluidic diode, a component known to mimic the behaviour of semiconductor diode. The study highlights a strong coupling between water and ion dynamics which leads to a water flow rectification inside the diode. The fifth and last chapter is a study of the origin of commonly observed pink noise (1=f) in ionic current measurements through nanopores
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Moreira, Tiago Augusto. "Análise experimental da influência da adição de nanopartículas a água no coeficiente de transferência de calor para escoamentos monofásicos e ebulição convectiva em microcanais." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/18/18147/tde-10032017-091729/.
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Dissipadores de calor baseados em microcanais são apresentados como solução para a remoção de fluxos de calor elevados em espaços restritos, pois proporcionam elevados coeficientes de transferência de calor quando comparados a canais convencionais. Tais trocadores também proporcionam elevadas razões entre a área superficial em contato com o refrigerante por unidade de volume do dissipador. Além dos microcanais, a utilização de nanofluidos também se apresenta como tecnologia com potencial de incremento do coeficiente de transferência de calor. Os nanofluidos consistem na adição de nanopartículas a um fluido base visando alterar suas propriedades de transporte termodinâmicas. Neste contexto, o objetivo do presente estudo é avaliar o coeficiente de transferência de calor para escoamentos monofásicos e ebulição convectiva de nanofluidos aquosos no interior de microcanais. Para isto, foram realizados experimentos em canais com diâmetro de 1,1 mm e comprimento de 200 mm para água deionizada, nanofluidos de alumina com diâmetros de 20-30 e 40-80 nm, nanofluidos de dióxido de silício com diâmetros de 15 e 80 nm, e nanofluidos de cobre com diâmetro de 25 nm. Estas soluções foram ensaiadas para concentrações volumétricas de nanopartículas de 0,001, 0,01 e 0,1, velocidades mássicas de 200, 400 e 600 kg/m2s e fluxos de calor de 20 a 350 kW/m2. A análise dos resultados revelou que a adição de nanopartículas a água deionizada proporciona o incremento do número de Nusselt para escoamentos monofásicos, principalmente na região inicial do tubo. Concluiu-se que os efeitos da adição de nanopartículas a um fluido base no coeficiente de transferência de calor durante a ebulição convectiva estão relacionados ao recobrimento da superfície com uma camada porosa. A deposição de nanopartículas com diâmetro inferior a 30 nm resultou na redução do coeficiente de transferência de calor e das instabilidades térmicas do escoamento em relação a água deionizada. O coeficiente de transferência de calor e as instabilidades térmicas não apresentaram variações significativas da deposição de nanopartículas com diâmetro superior a 40 nm. Por meio da análise da textura das superfícies recobertas e do critério de nucleação proposto por Kandlikar et al. (1997) concluiu-se que tal comportamento encontra-se associado aos efeitos do acabamento superficial na densidade de cavidades de nucleação ativas.Microchannels based heat exchangers were introduced as a solution to high heat flux removal in restrict spaces due to their high heat transfer coefficients compared to heat exchangers based on conventional channels. The high ratio of surface are per volume is an additional advantage to microchannels in relation to conventional channels. Beside the microchannels technology, the nanofluids also present itself as a technique with potential to increase the heat transfer coefficient. Nanofluids consist of a solution containing nanoparticles dispersed in a base fluid with the goal to improve its thermodynamic and transport properties. In this context, the objective of the present study is to evaluate the heat transfer coefficient for single-phase flow and convective boiling of aqueous nanofluids inside microchannels. Experiments were performed for channels with internal diameter of 1.1mm and 200 mm long for DI-water, nanofluids containing alumina- (nanoparticles diameters of 20-30 and 40-80 nm), silicon dioxide (nanoparticles diameters of 15 and 80 nm), and copper (nanoparticles diameter of 25 nm). These solutions were evaluated for volumetric concentrations of 0.001, 0.01 and 0.1%, mass velocities of 200, 400 and 600 kg/m2s and heat fluxes from 20 to 350 kW/m2. The analysis of the results revealed that the addition of nanoparticles to DI-water causes an increment in the Nusselt number for single phase flows, especially at the inlet of the tube. The results for flow boiling indicated that the effects of adding nanoparticles to the base fluid are related to the deposition on the heating surface of a nanoparticles porous layer due to the boiling process. The deposition of nanoparticles smaller than 30 nm promoted a reduction of the heat transfer coefficient compared to DI-water on a clean surface, and thermal instabilities were minimized. For the deposition of nanoparticles larger than 40 nm these parameters did not presented significant variations in comparison to DI-water. A combined analysis of the surfaces finishing and the criterion of Kandlikar et al. (1997) for bubble nucleation revealed that such behaviors are correlated to the effects of the surface texture associated to the boiling process on the density of active nucleation cavities.
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Cunha, Alex Pereira da. "A method for measuring contact angle and influence of surface fluid parameters on the boiling heat transfer performance /." Ilha Solteira, 2019. http://hdl.handle.net/11449/183048.
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Orientador: Elaine Maria CardosoResumo: O avanço de novas tecnologias, associado à minimização dos custos de fabricação e instala-ção, constitui um grande desafio para a área de refrigeração, uma vez que a geração de calor tem aumentado gradativamente nos últimos anos. Assim, a busca de novos fluidos com pro-priedades térmicas superiores aos comumente usados tornou-se indispensável para melhorar a eficiência energética. Nas últimas décadas os nanofluidos - dispersões de partículas de escala nanométrica (1 a 100nm) em um fluido-base - têm atraído especial interesse não somente da comunidade acadêmica, mas também da indústria em áreas como: a microeletrônica, microflu-ídica, transporte, manufatura, assistência médica, entre outras. O melhor desempenho térmico e a vasta gama de aplicações fazem dos nanofluidos potenciais substitutos dos refrigerantes utilizados em diversos segmentos da engenharia. Dentro desse contexto, o presente trabalho teve como objetivos: o estudo teórico e experimental da influência das propriedades termofísi-cas e concentração de nanofluidos, bem como, das características geométricas da superfície aquecedora sobre o ângulo de contato e a molhabilidade. Também, atenção foi dada à prepa-ração e caracterização dos nanofluidos (Al2O3-água e Fe2O3-água), por meio da análise expe-rimental da condutividade térmica e da viscosidade dinâmica para diferentes concentrações; uma bancada experimental, para aquisição de imagens de gota séssil, foi construída a fim de viabilizar as análises de ângulo de conta... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The advance of new technologies, associated to the minimization of manufacturing and installation costs, presents a great challenge for the refrigeration area, since the heat generation has increased in recent years. Thus, the search for new fluids with thermal properties higher than those commonly used has become indispensable to improve energy efficiency. In recent decades, nanofluids-dispersions of nanometer-scale particles (1 to 100 nm) in a base fluid - have attracted special interest not only from the academic community but also from industry in areas such as microelectronics, microfluidics, transport, manufacturing, medical assistance, among others. In this context, the present work had the following goals: the theoretical and experimental study of the influence of thermophysical properties and nanofluid concentration, as well as the geometric characteristics of the heating surface on the contact angle and wetta-bility. Attention was also given to the preparation and characterization of nanofluids (Al2O3-water and Fe2O3-water) by the experimental analysis of thermal conductivity and dynamic viscosity for different concentrations; an experimental apparatus for the acquisition of sessile droplet images was designed in order to analyze the contact angle and wettability; and a computational routine was developed to obtain the drop profile and the surface-fluid interaction for the different nanofluids and surfaces used. Based on database, it was possible to evaluate the pre... (Complete abstract click electronic access below)
Doutor
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Mondragón, Cazorla Rosa. "Estudio de la cinética de secado de gotas de nanofluidos, y caracterización microestructural y mecánica de los gránulos obtenidos." Doctoral thesis, Universitat Jaume I, 2013. http://hdl.handle.net/10803/664050.
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El proceso de secado por atomización interviene en numerosas aplicaciones industriales. Un campo de especial interés, en el que se utiliza dicho proceso es la obtención de gránulos nanoestructurados obtenidos a partir de materias primas de tamaño nanométrico. En este trabajo se ha llevado a cabo un estudio del proceso de secado de gotas de nanofluidos, en un levitador acústico. El estudio se ha extendido al secado de gotas de suspensiones conteniendo mezclas de nanopartículas y micropartículas. Se ha analizado y modelado la influencia de las variables de interés en la cinética de secado, el empaquetamiento de las partículas en el interior del gránulo, su microestructura interna y su resistencia mecánica. Finalmente, los resultados obtenidos en el secado de gotas individuales en el levitador acústico han sido validados a escala de planta piloto mediante el secado por atomización de diferentes suspensiones.The spray drying process is present in numerous industrial applications. A field of special interest, in which said process is used, is the obtaining of nanostructured granules from nano-sized raw materials. In this work, a study of the drying process of nanofluid droplets has been carried out in an acoustic levitator. The study has been extended to the drying of suspension droplets containing mixtures of nanoparticles and microparticles. The influence of the variables of interest on the kinetics of drying, the packing of the particles inside the granule, its internal microstructure and its mechanical resistance has been analyzed and modeled. Finally, the results obtained in the drying of individual droplets in the acoustic levitator have been validated at pilot plant scale by spray drying of different suspensions.
Books on the topic "Nanofluidlcs"
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Abgrall, Patrick. Nanofluidics. Boston: Artech House, 2009.
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1970-, Nguyen Nam-Trung, ed. Nanofluidics. Boston: Artech House, 2009.
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Li, Zhigang. Nanofluidics. Boca Raton : Taylor & Francis, a CRC title, part of the Taylor &: CRC Press, 2018. http://dx.doi.org/10.1201/b22007.
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Michaelides, Efstathios E. Nanofluidics. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-05621-0.
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Edel, Joshua, Aleksandar Ivanov, and MinJun Kim, eds. Nanofluidics. Cambridge: Royal Society of Chemistry, 2016. http://dx.doi.org/10.1039/9781849735230.
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Edel, Joshua, and Andrew deMello, eds. Nanofluidics. Cambridge: Royal Society of Chemistry, 2008. http://dx.doi.org/10.1039/9781847558909.
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Kleinstreuer, Clement. Microfluidics and Nanofluidics. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118749890.
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Prabhu, K. Narayan, ed. Nanofluids. 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International, 2012. http://dx.doi.org/10.1520/stp1567-eb.
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Nanofluids. West Conshohocken, PA: ASTM International, 2012.
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Li, Dongqing. Electrokinetic Microfluidics and Nanofluidics. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-16131-5.
Full textBook chapters on the topic "Nanofluidlcs"
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Han, Jongyoon. "Nanofluidics." In Introduction to Nanoscale Science and Technology, 575–97. Boston, MA: Springer US, 2004. http://dx.doi.org/10.1007/1-4020-7757-2_24.
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Yoda, Minami, Jean-Luc Garden, Olivier Bourgeois, Aeraj Haque, Aloke Kumar, Hans Deyhle, Simone Hieber, et al. "Nanofluidics." In Encyclopedia of Nanotechnology, 1543. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-90-481-9751-4_100500.
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Harikrishnan, S., and A. D. Dhass. "Nanofluids." In Thermal Transport Characteristics of Phase Change Materials and Nanofluids, 119–24. Boca Raton: CRC Press, 2022. http://dx.doi.org/10.1201/9781003163633-8.
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Harikrishnan, S., A. D. Dhass, and Hafiz Muhammad Ali. "Nanofluids." In Thermal Performance of Nanofluids in Miniature Heat Sinks with Conduits, 1–28. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-7845-5_1.
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Phan, Vinh-Nguyen, Nam-Trung Nguyen, Chun Yang, and Patrick Abgrall. "Applications of Nanofluidics." In Encyclopedia of Nanotechnology, 1–8. Dordrecht: Springer Netherlands, 2015. http://dx.doi.org/10.1007/978-94-007-6178-0_143-2.
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Aliano, Antonio, Giancarlo Cicero, Hossein Nili, Nicolas G. Green, Pablo García-Sánchez, Antonio Ramos, Andreas Lenshof, et al. "Applications of Nanofluidics." In Encyclopedia of Nanotechnology, 121–27. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-90-481-9751-4_143.
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Li, Zhigang. "Introduction to nanofluidics." In Nanofluidics, 29–44. Boca Raton : Taylor & Francis, a CRC title, part of the Taylor &: CRC Press, 2018. http://dx.doi.org/10.1201/b22007-2.
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Kim, Daejoong, Kilsung Kwon, Deok Han Kim, and Longnan Li. "Nanofluidic RED." In SpringerBriefs in Applied Sciences and Technology, 43–44. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-0314-2_6.
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Yoda, Minami, Jean-Luc Garden, Olivier Bourgeois, Aeraj Haque, Aloke Kumar, Hans Deyhle, Simone Hieber, et al. "Nanofluidic Channels." In Encyclopedia of Nanotechnology, 1543. Dordrecht: Springer Netherlands, 2012. http://dx.doi.org/10.1007/978-90-481-9751-4_100499.
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Michaelides, Efstathios E. "Fundamentals of Nanoparticle Flow and Heat Transfer." In Nanofluidics, 1–45. Cham: Springer International Publishing, 2014. http://dx.doi.org/10.1007/978-3-319-05621-0_1.
Full textConference papers on the topic "Nanofluidlcs"
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Han, Jongyoon, and Harold G. Craighead. "From microfluidics to nanofluidics: DNA separation using nanofluidic entropic trap array device." In Micromachining and Microfabrication, edited by Carlos H. Mastrangelo and Holger Becker. SPIE, 2000. http://dx.doi.org/10.1117/12.395654.
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Karnik, Rohit, Kenneth Castelino, Chuanhua Duan, Rong Fan, Peidong Yang, and Arun Majumdar. "Nanofluidic Devices for Sensing and Flow Control." In ASME 4th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2006. http://dx.doi.org/10.1115/icnmm2006-96156.
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Nanofluidics is concerned with fluidic channels that are typically 1–100 nm in size. We have fabricated nanofluidic devices using both 1-D silica nanotubes and 2-D nanochannels to explore transport phenomena at the nanoscale. Here we review our work on 2-D nanochannels that provide confinement in one dimension. Our work mainly deals with two aspects of nanofluidics (a) effects related to electrostatic interactions and (b) effects related to biomolecule size. Surface charge plays an important role in nanofluidic channels, when the channel size is comparable to the Debye length. Using both electrical conductance measurements and fluorescence imaging, we studied the effects of surface charge in our nanofluidic devices, and demonstrated that the environment in nanochannels is governed by surface charge. We modified the nanochannel surface and showed that these modifications can be sensed by measuring ionic conductance of the nanochannels. Further, binding reactions involving biomolecules can be sensed at both low and high ionic concentrations. Our results showed that at low concentrations, conductance is governed by biomolecule charge, while at high concentrations it is governed by biomolecule size. Based on electrostatic effects in nanochannels, we also developed a nanofluidic transistor for flow control. This metal-oxide-solution field effect transistor was fabricated by patterning a metal gate electrode over nanochannels, similar to a MOSFET. Just as the gate voltage of a MOSFET controls carrier concentration in the semiconductor, we demonstrated that the gate voltage in a nanofluidic transistor controls the concentration of ions and biomolecules in the nanochannel, and hence controls their transport. Our fabrication process uses standard lithography, and is amenable to making networks of nanochannels. It suggests that rationally designed nanofluidic networks could be developed using this process for applications in sample preparation, sensing and switching. We are currently studying flow control and switching using field-effect, as well as ionic transport using patterned surface charge in nanofluidic devices.
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Wei, Jianjun, Hongjun Song, Sameer Singhal, Matthew Kofke, Madu Mendis, and David Waldeck. "An In-Plane Nanofluidic Nanoplasmonics-Based Platform for Biodetection." In ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/mnhmt2012-75206.
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This paper reports a new nanofluidic plasmonics-based sensing platform which can be readily integrated with microfluidics devices, and potentially enable an in-parallel transmission surface plasmon resonance (SPR), lab-on-chip sensing technology. The technology overcomes the current SPR size limitations through a combination of nanofluidics and nanoplasmonics in a rationally designed in-plane nanoslit array capable of concurrent plasmonic sensing and confined-flow for analyte delivery. This work is leveraged on our previous work of using nanoslit metal films for SPR sensing [1, 2], and the in-plane nanofluidic nanoplasmonic platform is different from recently reported nanohole-based nanofluidic plasmonics sensors [3, 4]. The work presented here includes an integrated device with nanofluidic nanoplasmonic arrays interfacing with microfluidic channels, and preliminary findings, from both theoretical and experimental fronts, of the device for bio-sensing.
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Mills, K. L., Dongeun Huh, Shuichi Takayama, and M. D. Thouless. "Adjustable Nanofluidic Channels by Tunnel Cracking of a Constrained Brittle Layer." In ASME 2008 6th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2008. http://dx.doi.org/10.1115/icnmm2008-62164.
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There is widespread and rapidly increasing interest in adopting nanofluidics as a strategy for developing new capabilities in various scientific areas. A fast, easy, and inexpensive method for creating nanochannels may address technical limitations associated with the limited availability of conventional nanofabrication technologies and contribute to expanding the application of nanofluidics to areas of biological or chemical interest. For example, there is considerable interest in the controlled confinement and manipulation of single polymeric or bio-molecules (e.g., DNA) for analysis. Motivated by this, we present here a cracking-based method for fabrication of adjustable nanofluidic channels.
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Scheibel, Olivia V., David Lanza, and Michael G. Schrlau. "Template-Based Synthesis of Integrated Carbon Micro- and Nanostructures." In ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/imece2017-71674.
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This work demonstrates the manufacturing process of micro- and nanofluidic devices consisting of independent, aligned carbon pipes with potential applications as micro- and nanoscale dispensing systems, electrodes, and tools with which to study fundamental micro- and nanofluidics. A low-cost, high-throughput chemical vapor deposition (CVD) process was utilized to deposit carbon within novel silica-based templates. This simple template-based manufacturing process allows the carbon devices to be integrated into millimeter scale silica-based templates without micro- or nanoassembly, facilitating commercialization. Furthermore, the carbon-based devices were designed to readily integrate into standard laboratory equipment, promoting broad utilization. Herein, a repeatable methodology for fabricating multifunctional, carbon-based micro- and nanofluidic devices as well as establishing relationships between parameters at each stage of fabrication and the final geometry, including diameter and wall thickness of the carbon structures, of the device is presented.
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O’Hanley, Harry, Jacopo Buongiorno, Thomas McKrell, and Lin-wen Hu. "Measurement and Model Correlation of Specific Heat Capacity of Water-Based Nanofluids With Silica, Alumina and Copper Oxide Nanoparticles." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-62054.
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Nanofluids are being considered for heat transfer applications. However, their thermo-physical properties are poorly known. Here we focus on nanofluid specific heat capacity. Currently, there exist two models to predict a nanofluid’s specific heat capacity as a function of nanoparticle concentration and material. Model I is a straight volume-weighted average; Model II is based on the assumption of thermal equilibrium between the particles and the surrounding fluid. These two models give significantly different predictions for a given system. Using differential scanning calorimetry, the specific heat capacities of water based silica, alumina, and copper oxide nanofluids were measured. Nanoparticle concentrations were varied between 5wt% and 50wt%. Test results were found to be in excellent agreement with Model II, while the predictions of Model I deviate very significantly from the data.
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Alfi, M., H. Nasrabadi, and D. Banerjee. "Confinement Effects on Phase Behavior of Hydrocarbon in Nanochannels." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-52845.
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Several researchers have recently studied the phase behavior of petroleum fluids in shale systems. There is a general agreement that the confined PVT properties in shale are substantially different from the corresponding bulk properties. These differences have significant impact on the prediction of well performance and ultimate recovery in shale reservoirs. Experimental measurements of fluid properties in shale rocks are currently not available. This has led to significant amount of uncertainty in phase behavior calculations for shale reservoirs. In this study, experimental validation of numerical predictions for phase behavior of various hydrocarbons confined in nanochannels was performed using a nanofluidics platform. The nanofluidics platform was designed, fabricated and tested at different temperatures. Design of the nanochannel is described in this paper. In this study, a nanochannel device (similar to Duan and Majumdar 2010) was designed, fabricated, packaged and tested. The reservoirs in the nanofluidic chip were filled with various hydrocarbon liquids (e.g. n-decane). The temperature was varied at a constant pressure, during which epifluorescence imaging was performed to measure the bubble nucleation temperature, i.e., the temperature corresponding to the formation of the first bubble of gas (i.e., to determine bubble-point pressure and temperature relationship).
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Taylor, Robert A., Patrick E. Phelan, Ronald J. Adrian, Todd Otanicar, and Ravi S. Prasher. "Experimental Results for Light-Induced Boiling in Water-Based Graphite Nanoparticle Suspensions." In ASME 2009 Heat Transfer Summer Conference collocated with the InterPACK09 and 3rd Energy Sustainability Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/ht2009-88176.
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One relatively simple subset of nanotechnology is nanofluids, obtained by the addition of nanoparticles to a conventional base fluid. The promise of nanofluids stems from the fact that at relatively small particle loading (typically <1% by volume) significant enhancement in thermal transport may be possible [1–3]. Since there are a wide variety of nanoparticle materials to choose from, nanofluidic systems can be tuned to fit a number of applications. This research focuses on direct thermal collection of light energy using highly absorptive nanofluids. Experimental tests are conducted using a 0.1% by volume graphite/water (30nm nominal particle diameter) nanofluid exposed to a 130 mW, 532 nm, continuous laser. A lens is placed between the laser and the fluid to achieve a high-energy flux (∼ 490 Wcm−2). Since initially over 99.9% of the light is absorbed in a path length of 0.1 mm, the irradiated portion of the base fluid collects enough energy to vaporize. Heuristic methods of analysis demonstrate this situation incorporates several interesting modes of heat transfer and fluid mechanics. These experiments also reveal the possibility for novel solar collectors in which the working fluid directly absorbs energy and undergoes phase change in a single step.
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Takayama, Shuichi, Yi-Chung Tung, and Bor-Han Chueh. "Biological Micro/Nanofluidics." In ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer. ASMEDC, 2008. http://dx.doi.org/10.1115/mnht2008-52087.
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Many biological studies, drug screening methods, and cellular therapies require culture and manipulation of living cells outside of their natural environment in the body. The gap between the cellular microenvironment in vivo and in vitro, however, poses challenges for obtaining physiologically relevant responses from cells used in basic biological studies or drug screens and for drawing out the maximum functional potential from cells used therapeutically. One of the reasons for this gap is because the fluidic environment of mammalian cells in vivo is microscale and dynamic whereas typical in vitro cultures are macroscopic and static. This presentation will give an overview of efforts in our laboratory to develop programmable microfluidic systems that enable spatio-temporal control of both the chemical and fluid mechanical environment of cells. The technologies and methods close the physiology gap to provide biological information otherwise unobtainable and to enhance cellular performance in therapeutic applications. Specific biomedical topics that will be discussed include subcellular signalling in normal and cancer cells, in vitro fertilization on a chip, studies of the effect of physiological and pathological fluid mechanical stresses on endothelial and epithelial cells, and microfluidic stem cell engineering. In the nanoscale regime, tunable nanochannels that can manipulate single DNA molecules will be discussed.
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Erickson, David, Teresa Emery, Troy Rockwood, Axel Scherer, and Demetri Psaltis. "Integration of Sub-Wavelength Nanofluidics With Photonic Crystals." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81715.
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“Optofluidics” represents the marriage of optics, optoelectronics and nanophotonics with fluidics. Such integration represents a new approach for dynamic manipulation of optical properties at length scales both greater than and smaller than the wavelength of light with applications ranging from reconfigurable photonic circuits to fluidically adaptable optics to high sensitivity bio-detection currently under development. The capabilities in terms of fluidic control, mixing, miniaturization and optical property tuning afforded by micro-, nano-fluidics combined with soft lithography based fabrication provides an ideal platform upon which to build such devices. Here we present our technique for integrating soft lithography based nanofluidics with e-beam lithography defined silicon-on-insulator photonic crystals. We demonstrate nanofluidic addressability of single, sub-wavelength, defects within the planar photonic crystal and the dynamic tuning of the guided mode. In this paper we focus on the fabrication, integration and experimental details of this work.
Reports on the topic "Nanofluidlcs"
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Pawel Keblinski. Fundamentals of Energy Transport in Nanofluids. Office of Scientific and Technical Information (OSTI), February 2007. http://dx.doi.org/10.2172/924115.
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Ramsey, J. Michael. Nanofluidic Structures for Electrokinetic-Based Hydraulic Pumps. Office of Scientific and Technical Information (OSTI), June 2004. http://dx.doi.org/10.2172/839258.
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Gourley, Paul Lee, Anthony Eugene McDonald, and Judy K. Hendricks. Nanofluidic devices for rapid detection of virus particles. Office of Scientific and Technical Information (OSTI), January 2005. http://dx.doi.org/10.2172/921716.
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Gharagozloo, Patricia E., and Kenneth E. Goodson. Characterization and modeling of thermal diffusion and aggregation in nanofluids. Office of Scientific and Technical Information (OSTI), May 2010. http://dx.doi.org/10.2172/993305.
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Jeyashekar, Nigil S. Scanning Electron Microscope Studies on Aggregation Characteristics of Alumina Nanofluids. Fort Belvoir, VA: Defense Technical Information Center, August 2013. http://dx.doi.org/10.21236/ada602578.
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Fornasiero, Francesco. Unraveling the physics of nanofluidic phenomena at the single-molecule level. Office of Scientific and Technical Information (OSTI), October 2015. http://dx.doi.org/10.2172/1240944.
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Cropek, Donald M., Paul W. Bohn :In-Hyoung, Jonathan Sweedler, Yi Lu, Carla Swearingen, and Daryl Wernette. Metal Ion Sensor with Catalytic DNA in a Nanofluidic Intelligent Processor. Fort Belvoir, VA: Defense Technical Information Center, February 2005. http://dx.doi.org/10.21236/ada631384.
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Taborek, Peter. Nanoscale Heat Transfer Due to Near Field Radiation and Nanofluidic Flows. Fort Belvoir, VA: Defense Technical Information Center, July 2015. http://dx.doi.org/10.21236/ada625941.
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Globus, Tatiana, Aaron Moyer, Jerome Ferrance, Igor Sizov, and Tatyana Khromova. Development of a Biosensor Nanofluidic Platform for Integration with Terahertz Spectroscopic System. Fort Belvoir, VA: Defense Technical Information Center, January 2013. http://dx.doi.org/10.21236/ada587044.
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Routbort, J., D. Singh, E. Timofeeva, W. Yu, and D. France. Developmemt, characterization, production, and demonstration of nanofluids for industrial cooling applications. Quarterly report #7. Office of Scientific and Technical Information (OSTI), July 2010. http://dx.doi.org/10.2172/983764.
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