Academic literature on the topic 'NANO PHASE CHANGE'

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Journal articles on the topic "NANO PHASE CHANGE"

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Long, Jian You. "Study on Phase-Change Temperature and Latent Heat of Organic Phase-Change Nano-Fluid." Advanced Materials Research 152-153 (October 2010): 1591–94. http://dx.doi.org/10.4028/www.scientific.net/amr.152-153.1591.

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Nano-aluminum, which has high thermal conductivity and good compatibility, was added into paraffin to improve its thermal conductivity. Surface modified technology was adopted and dispersant was used to prepare uniform and stable organic phase-change nano-fluid of paraffin and nano-aluminum. Experiments were conducted to test the phase-change temperature and latent heat of the prepared organic phase-change nano-fluid. Results show that the addition of nano-aluminum has no effect on phase-change temperature, but it changes phase-change latent heat of the prepared organic phase-change nano-fluid. Reduced degree of the latent heat is nearly proportional to the quantity of the added nano-aluminum.
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Chu, Cheng Hung, Ming Lun Tseng, Chiun Da Shiue, Shuan Wei Chen, Hai-Pang Chiang, Masud Mansuripur, and Din Ping Tsai. "Fabrication of phase-change Ge_2Sb_2Te_5 nano-rings." Optics Express 19, no. 13 (June 15, 2011): 12652. http://dx.doi.org/10.1364/oe.19.012652.

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Sinha-Ray, S., R. P. Sahu, and A. L. Yarin. "Nano-encapsulated smart tunable phase change materials." Soft Matter 7, no. 19 (2011): 8823. http://dx.doi.org/10.1039/c1sm05973d.

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Pereira, José, Ana Moita, and António Moreira. "An Overview of the Nano-Enhanced Phase Change Materials for Energy Harvesting and Conversion." Molecules 28, no. 15 (July 30, 2023): 5763. http://dx.doi.org/10.3390/molecules28155763.

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This review offers a critical survey of the published studies concerning nano-enhanced phase change materials to be applied in energy harvesting and conversion. Also, the main thermophysical characteristics of nano-enhanced phase change materials are discussed in detail. In addition, we carried out an analysis of the thermophysical properties of these types of materials as well as of some specific characteristics like the phase change duration and the phase change temperature. Moreover, the fundamental improving techniques for the phase change materials for solar thermal applications are described in detail, including the use of nano-enhanced phase change materials, foam skeleton-reinforced phase change materials, phase change materials with extended surfaces, and the inclusion of high-thermal-conductivity nanoparticles in nano-enhanced phase change materials, among others. Those improvement techniques can increase the thermal conductivity of the systems by up to 100%. Furthermore, it is also reported that the exploration of phase change materials enhances the overall efficiency of solar thermal energy storage systems and photovoltaic-nano-enhanced phase change materials systems. Finally, the main limitations and guidelines for future research in the field of nano-enhanced phase change materials are summarized.
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Long, Jian You. "Study on Thermal Conductivity of Organic Phase-Change Nano-Fluid." Advanced Materials Research 152-153 (October 2010): 1579–82. http://dx.doi.org/10.4028/www.scientific.net/amr.152-153.1579.

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Nano-aluminum, which has high thermal conductivity and good compatibility, was added into paraffin to improve its thermal conductivity. Surface modified technology was adopted and dispersant was used to prepare uniform and stable organic phase-change nano-fluid of paraffin and nano-aluminum. Transient plane source method was used to test the thermal conductivity of the prepared organic phase-change nano-fluid. Results showed that the addition of nano-aluminum largely improved the thermal conductivity of paraffin. After the formula of Lu and Lin was modified, a calculation model for thermal conductivity of the organic phase-change nano-fluid was deduced. And experimental results showed that the results of calculation agreed that of experiment very well.
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Kersting, Benedikt, and Martin Salinga. "Exploiting nanoscale effects in phase change memories." Faraday Discussions 213 (2019): 357–70. http://dx.doi.org/10.1039/c8fd00119g.

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Shi, L. P., and T. C. Chong. "Nanophase Change for Data Storage Applications." Journal of Nanoscience and Nanotechnology 7, no. 1 (January 1, 2007): 65–93. http://dx.doi.org/10.1166/jnn.2007.18007.

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Phase change materials are widely used for date storage. The most widespread and important applications are rewritable optical disc and Phase Change Random Access Memory (PCRAM), which utilizes the light and electric induced phase change respectively. For decades, miniaturization has been the major driving force to increase the density. Now the working unit area of the current data storage media is in the order of nano-scale. On the nano-scale, extreme dimensional and nano-structural constraints and the large proportion of interfaces will cause the deviation of the phase change behavior from that of bulk. Hence an in-depth understanding of nanophase change and the related issues has become more and more important. Nanophase change can be defined as: phase change at the scale within nano range of 100 nm, which is size-dependent, interface-dominated and surrounding materials related. Nanophase change can be classified into two groups, thin film related and structure related. Film thickness and clapping materials are key factors for thin film type, while structure shape, size and surrounding materials are critical parameters for structure type. In this paper, the recent development of nanophase change is reviewed, including crystallization of small element at nano size, thickness dependence of crystallization, effect of clapping layer on the phase change of phase change thin film and so on. The applications of nanophase change technology on data storage is introduced, including optical recording such as super lattice like optical disc, initialization free disc, near field, super-RENS, dual layer, multi level, probe storage, and PCRAM including, superlattice-like structure, side edge structure, and line type structure. Future key research issues of nanophase change are also discussed.
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Teng, Tun Ping, Bo Gu Lin, and Yun Yu Yeh. "Characterization of Heat Storage by Nanocomposite-Enhanced Phase Change Materials." Advanced Materials Research 287-290 (July 2011): 1448–55. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.1448.

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This study involved a two-step method of adding multi-walled carbon nanotube (MWCNTs) and alumina (Al2O3) nanoparticles to paraffin wax, forming nanocomposite-enhanced phase change materials (NEPCMs). The NEPCMs in a phase change experiment were influenced by the concentrations of the nano-materials and the heating temperature of water. The objective of this paper is to investigate the optimal parameters of added nano-materials. The experimental results show that the phase change temperature of the paraffin wax slightly increases after adding the nano-materials to the paraffin wax. In addition, the nano-materials in the paraffin wax will reduce the temperature difference between test samples and heating water, indicating that adding the nano-materials can effectively reduce the thermal resistance of the experimental samples and improve the efficiency of thermal energy storage.
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Irwan, M. A. M., C. S. Nor Azwadi, Y. Asako, and J. Ghaderian. "Review on numerical simulations for nano-enhanced phase change material (NEPCM) phase change process." Journal of Thermal Analysis and Calorimetry 141, no. 2 (November 21, 2019): 669–84. http://dx.doi.org/10.1007/s10973-019-09038-2.

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Rao, Feng, Kun Ren, Yifeng Gu, Zhitang Song, Liangcai Wu, Xilin Zhou, Bo Liu, Songlin Feng, and Bomy Chen. "Nano composite Si2Sb2Te film for phase change memory." Thin Solid Films 519, no. 16 (June 2011): 5684–88. http://dx.doi.org/10.1016/j.tsf.2011.03.015.

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Dissertations / Theses on the topic "NANO PHASE CHANGE"

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Huang, Yaoting. "Fundamental studies on nano-composite phase change materials (PCM) for cold storage applications." Thesis, University of Birmingham, 2019. http://etheses.bham.ac.uk//id/eprint/8844/.

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This thesis studies the thermophysical properties and the phase change behaviour of EG-water and Salt-water based PCMs for cold storage applications, and investigates the role of adding MCNT on the thermophysical properties and the phase change processes. First, the structure of MCNT clusters is linked to the rheological behaviour of the nanofluids by fitting the experimental viscosity data to the modified K-D model. Second, the MCNT cluster information is used to predict thermal conductivity. The effective thermal conductivity of nanofluids not only relies on the particle concentration, but also depends on the particle cluster structure. The specific heat of MCNT nanofluids is decreasing proportionally with the concentration of MCNT. The supercooling degree of EG-water and salt-water based samples can be reduced by adding MCNT particles. The crystallization process of salt-water basefluid and nanofluid was observed and recorded under an optical microscope with cooling stage. Adding MCNT can promote the crystal growth rate.
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Xing, Keqiang. "Numerical Investigation on the Heat Transfer Enhancement Using Micro/Nano Phase-Change Particulate Flow." FIU Digital Commons, 2007. http://digitalcommons.fiu.edu/etd/28.

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The introduction of phase change material fluid and nanofluid in micro-channel heat sink design can significantly increase the cooling capacity of the heat sink because of the unique features of these two kinds of fluids. To better assist the design of a high performance micro-channel heat sink using phase change fluid and nanofluid, the heat transfer enhancement mechanism behind the flow with such fluids must be completely understood. A detailed parametric study is conducted to further investigate the heat transfer enhancement of the phase change material particle suspension flow, by using the two-phase non-thermal-equilibrium model developed by Hao and Tao (2004). The parametric study is conducted under normal conditions with Reynolds numbers of Re=600-900 and phase change material particle concentrations ¡Ü0.25 , as well as extreme conditions of very low Reynolds numbers (Re < 50) and high phase change material particle concentration (0.5-0.7) slurry flow. By using the two newly-defined parameters, named effectiveness factor and performance index, respectively, it is found that there exists an optimal relation between the channel design parameters, particle volume fraction, Reynolds number, and the wall heat flux. The influence of the particle volume fraction, particle size, and the particle viscosity, to the phase change material suspension flow, are investigated and discussed. The model was validated by available experimental data. The conclusions will assist designers in making their decisions that relate to the design or selection of a micro-pump suitable for micro or mini scale heat transfer devices. To understand the heat transfer enhancement mechanism of the nanofluid flow from the particle level, the lattice Boltzmann method is used because of its mesoscopic feature and its many numerical advantages. By using a two-component lattice Boltzmann model, the heat transfer enhancement of the nanofluid is analyzed, through incorporating the different forces acting on the nanoparticles to the two-component lattice Boltzmann model. It is found that the nanofluid has better heat transfer enhancement at low Reynolds numbers, and the Brownian motion effect of the nanoparticles will be weakened by the increase of flow speed.
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Hernandez, Gerardo Rodriguez. "Study of mixed mode electro-optical operations of Ge2Sb2Te5." Thesis, University of Oxford, 2017. https://ora.ox.ac.uk/objects/uuid:5bb8c1f5-2f4b-4eb0-a61a-3978af04211f.

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Chalcogenide based Phase Change Materials are currently of great technological interest in the growing field of optoelectronics. Ge2Sb2Te5 (GST) is the most widely studied phase change material, and it has been commercially used in both optical and electronic data storage applications, due to its ability to switch between two different atomic configurations, at high speed and with low power consumption, as well as its high optical and electrical contrast between amorphous and crystalline states. Despite its well-known optical and electrical properties, the operation in combination of optical and electrical domains has not yet been fully investigated. This work studies the operation of GST nano-devices exposed to a combination of optical and electrical stimuli or mixed mode by asking, is it possible to electrically measure an optically induced phase change, or vice versa? If so, how do the optical and electrical responses relate to each other, and is it possible to operate GST with a combination of optical and electrical signals? What are the technical constraints that need to be considered in order to fabricate GST devices that could be operated either optically or electrically? In order to answer these questions, experiments that characterized the optical and electrical responses of GST based nano-devices were performed. It was found that different crystallization mechanisms may have influence in the response, and that the thermal and optical design characteristics of the device play a key role in its operation. Finally a proof of principle, of an opto-electonic memory device that can be read electrically, reset optically and write electrically, is presented. This opens up possibilities for the development of new opto-eloectronic applications such as non-volatile interfaces between future photonics and electronics, high speed optical communication detectors, high speed cameras, artificial retinas and many more.
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Zhang, Guanhua. "Fabrication, characterization and thermo-physical properties of micro- and nano- scaled phase change materials for thermal energy storage." Thesis, University of Warwick, 2013. http://wrap.warwick.ac.uk/57041/.

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Latent heat storage is one of the most efficient ways of storing thermal energy. Organic phase change materials are latent heat storage materials and they have been widely used as suitable materials for thermal energy storage applications due to their high latent heat and small temperature difference between storing and releasing heat. In this thesis, micro- and nano- scaled phase change materials were fabricated for thermal energy storage. A novel microencapsulated phase change material slurry (MPCS) was introduced by dispersing microencapsulated phase change materials (MEPCMs) into water with an amount of surfactants and its thermal and rheological properties were also investigated. The results showed that MPCS fabricated in the current research are suitable for potential application as heat transfer media in the thermal energy storage. A new methodology was proposed to investigate the heat transfer characteristics of MPCSs. Experiments were carried out in laminar, transition and turbulent flow for MPCSs in a circular tube under constant heat flux, respectively. The experimental results demonstrated that in comparison to water as a heat transfer fluid at the same flow rate, the heat transfer of 10 wt. % MPCS could be enhanced by 10 % in transition flow condition while the PCM particles were in solid/liquid state, and the heat transfer of 5 wt. % MPCS could be enhanced by 21.9 % and 19.2 % in turbulent flow condition while the PCMs are in solid and solid/liquid states, respectively. Nevertheless, the heat transfer enhancement depends on the combination factors, including concentration of the slurry and flow rate of the slurry. A novel heat transfer fluid containing microencapsulated phase change material and multi-walled carbon nanotubes was prepared. The results showed that addition of MWCNTs to microencapsulated phase change material slurry can effectively improve the thermal conductivity of suspensions and it is also found that a blend of 10 wt. % MEPCM and 1 wt. % MWCNTs suspension can achieve the best thermal performance and stability among other blends in the experiment. A novel nanocapsule containing n-octadecane with an average 50 nm thick shell of poly (ethyl methacrylate) (PEMA), and with a core/shell weight ratio of 80/20 was synthesized by direct miniemulsion method. The results showed that PEMA/octadecane nanocapsule had good thermo-physical properties and had much higher encapsulation ratio (89.5%) and encapsulation efficiency (88.9%). For the first time, a novel PCM nanoparticle suspension (nano-PCS) was synthesized by direct miniemulsion method for thermal energy system application. It was found that the nano-PCSs had good thermo-physical properties and durability. All nano-PCSs presented narrow size distribution and stable particles. In comparison to the convectional PCM emulsion and MPCS, the nano-PCS tends to be more stable and is much easier and cheaper to fabricate in terms of the method and materials used, however, the heat transfer characteristics of the nano-PCS require further experimental investigation
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Wang, Yuan. "Liquid-vapour phase change and multiphase flow heat transfer in single micro-channels using pure liquids and nano-fluids." Thesis, University of Edinburgh, 2011. http://hdl.handle.net/1842/5752.

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Heat management in high thermal-density systems such as CPU chips, nuclear reactors and compact heat exchangers is confronting rising challenges due to ever more miniaturized and intensified processes. While searching for heat transfer enhancement, micro-channel flow boiling and the usage of high thermal potential fluids such as nanofluids are found to be efficient heat removal approaches. However, the limited understanding of micro-scale multiphase flows impedes wider applications of these techniques. In this thesis work, liquid-vapour phase change and multiphase flow heat transfer in micro-channels were experimentally investigated. Included are studies on the single phase friction, vapour dynamics, liquid meniscus evaporation, two-phase flow instabilities and heat transfer. An experimental system was built. Rectangular microchannels with different hydraulic diameters (571 μm, 762 μm and 1454 μm) and crosssectional aspect ratios were selected. Transparent heating was utilised by coating the micro-channels with a layer of tantalum on the outer surfaces. FC-72, n-pentane, ethanol, and ethanol-based Al2O3 nanofluids were used as working fluids. Pressures and temperatures at micro-channel inlet and outlet were acquired. Simultaneous visualisation and thermographic profiles were monitored. Single phase friction of pure liquids and nanofluids mostly showed good agreement with the conventional theory. The discrepancies were associated with hydrodynamic developing flow and the early transition to turbulent flow, but nanoparticle concentration showed minor impact. After boiling incipient, the single vapour bubble growth and flow regimes were investigated, exploring the influences of flow and thermal conditions as well as the micro-channel geometry on vapour dynamics. In addition, liquid meniscus evaporation as the main heat transfer approach at thin liquid films in micro-channels was studied particularly. Nanoparticles largely enhanced meniscus stability. Besides, flow instabilities were analyzed based on the pressure drop and channel surface temperature fluctuations as well as the synchronous visualization results. Moreover, study on flow boiling heat transfer was undertaken, the corresponding heat transfer characteristics were presented and the heat transfer mechanisms were elucidated. Furthermore, ten existing heat transfer correlations were assessed. A modified heat transfer correlation for high aspect ratio micro-channel flow boiling was proposed. The crucial role of liquid property and microchannel aspect-ratio on flow boiling heat transfer was highlighted.
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John, Jimmy. "VO2 nanostructures for dynamically tunable nanophotonic devices." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI044.

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L'information est devenue le bien le plus précieux au monde. Ce mouvement vers la nouvelle ère de l'information a été propulsé par la capacité à transmettre l'information plus rapidement, à la vitesse de la lumière. Il est donc apparu nécessaire de mener des recherches plus poussées pour contrôler plus efficacement les supports d'information. Avec les progrès réalisés dans ce secteur, la plupart des technologies actuelles de contrôle de la lumière se heurtent à certains obstacles tels que la taille et la consommation d'énergie et sont conçues pour être passives ou sont limitées technologiquement pour être moins actives (technologie Si-back). Même si rien ne voyage plus vite que la lumière, la vitesse réelle à laquelle les informations peuvent être transportées par la lumière est la vitesse à laquelle nous pouvons la moduler ou la contrôler. Ma tâche dans cette thèse visait à étudier le potentiel du VO2, un matériau à changement de phase, pour la nano-photonique, avec un accent particulier sur la façon de contourner les inconvénients du matériau et de concevoir et démontrer des dispositifs intégrés efficaces pour une manipulation efficace de la lumière à la fois dans les télécommunications et le spectre visible. En outre, nous démontrons expérimentalement que les résonances multipolaires supportées par les nanocristaux de VO2 (NC) peuvent être réglées et commutées dynamiquement en exploitant la propriété de changement de phase du VO2. Et ainsi atteindre l'objectif d'adaptation de la propriété intrinsèque basée sur le formalisme de Mie en réduisant les dimensions des structures de VO2 comparables à la longueur d'onde de fonctionnement, créant un champ d'application pour un métamatériau accordable défini par l'utilisateur
Information has become the most valuable commodity in the world. This drive to the new information age has been propelled by the ability to transmit information faster, at the speed of light. This erupted the need for finer researches on controlling the information carriers more efficiently. With the advancement in this sector, majority of the current technology for controlling the light, face certain roadblocks like size, power consumption and are built to be passive or are restrained technologically to be less active (Si- backed technology). Even though nothing travels faster than light, the real speed at which information can be carried by light is the speed at which we can modulate or control it. My task in this thesis aimed at investigating the potential of VO2, a phase change material, for nano-photonics, with a specific emphasis on how to circumvent the drawbacks of the material and to design and demonstrate efficient integrated devices for efficient manipulation of light both in telecommunication and visible spectrum. In addition to that we experimentally demonstrate the multipolar resonances supported by VO2 nanocrystals (NCs) can be dynamically tuned and switched leveraging phase change property of VO2. And thus achieving the target tailoring of intrinsic property based on Mie formalism by reducing the dimensions of VO2 structures comparable to the wavelength of operation, creating a scope for user defined tunable metamaterial
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Ray, Kamal Kanti. "Characterization of phase state, morphological, mechanical and electrical properties of nano- and macro-dimensional materials." Diss., University of Iowa, 2019. https://ir.uiowa.edu/etd/7017.

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The importance of studying the physico-chemical properties of nano-dimensional materials has gained significant attention in the fields of semiconductors, pharmaceuticals, materials science, and atmospheric chemistry owing to the differences in physical properties between macro- and nano-dimensional solids. Nonetheless, direct studies of physical properties of materials at nanoscale is limited in part due to their inherent size constraints and experimental limitations. However, development of atomic force microscopy (AFM) led to the implementation of methods to characterize a wide range of physical properties, including – but not limited to – mechanical properties, electrical properties, viscoelastic properties, and surface tension. Herein, the dissertation focuses on AFM-based method development for characterization of atmospheric particles as well as understanding the relationship between structure and physical properties of organic solids at both macro- and nano-dimensions. In the atmospheric chemistry realm, the combined aerosol effect on the climate and environment has significant uncertainty in part due to lack of direct characterization of their physico-chemical properties. The difficulty in assessing the physical and chemical properties arises due to the presence of diversified aerosol sources, which in turn influences the size, morphology, phase states and chemical compositions. Sea spray aerosols (SSAs) are the second-largest source of aerosols in the atmosphere. Studying SSAs – especially in submicrometer-dimensions – requires high-resolution microscopy techniques such as AFM. AFM can be used for imaging of individual aerosols, quantifying organic volume fraction for core-shell morphologies, measuring water uptake, quantifying surface tension of individual droplets, and measuring mechanical and viscoelastic properties of materials. Herein, we employed AFM-based morphology and force spectroscopy studies to correlate the 3D morphology, phase state, and viscoelastic properties of selected single-component chemical systems found in sea spray aerosol (SSA). We established a quantitative framework toward differentiation of the solid, semisolid and liquid phase states of individual particles by utilizing both relative indentation depth (RID) and viscoelastic response distance (VRD) data obtained from the force−distance plots. Moreover, we established a semi-quantitative and quick phase assessment by measuring the aspect ratio (AR) that refers the extent of particle spreading as a result of impaction. Overall, the established AFM-based quantitative and semi-quantitative phase identification method can be utilized to assess the phases of aerosols irrespective of chemical identity. Next, we investigated the factors that may control the electrical and mechanical properties of pharmaceutical and organic semiconducting materials in nano- and macro-dimensions. Understanding the structure-property relationship of materials, especially in the nano-dimension, is necessary for proper drug design and development of organic semiconducting materials. In this context, cocrystals provide a means to modulate the physico-chemical properties of organic solids. For example, the modulation of the mechanical properties is important in the pharmaceutical industry for improving the tabletability. The mechanical properties may be affected by packing arrangement, interaction strength and type, and atomic and chemical composition. Herein, we report the influence of alkane and alkene functional groups on the mechanical properties of organic solids based on salicylic acid (SA). The approach affords both isostructural and polymorphic solids. The isostructural alkane functional solid exhibits a two-fold larger Young’s modulus (YM) compared to the cocrystal with the alkene, where the YM refers to the stiffness of the material. Here, the higher YM values are attributed to the presence of a bifurcated weak C-H···O interactions involving the alkane and neighboring SA molecules. On the other hand, in the case of alkene polymorphisms, molecular packing with column arrangement shows higher YM values compared to the herringbone arrangements. Thus, functional groups and crystal arrangements influence the stiffness of the solid organic cocrystals. Moreover, we report the modulation of mechanical properties of salicylic acid (SA) through cocrystallization by variation of propane and butane functionality with bipyridine coformers. We show that the variation of propane and butane functionality in bipyridine coformer with salicylic acid leads to synthesis of cocrystal and salt-cocrystal, respectively. The AFM nanoindentation study revealed that the Young’s modulus values follow the order salicylic acid < cocrystal << salt-cocrystal. The highest Young’s modulus values of the salt-cocrystal, among the studied systems, are attributed to the presence of strong N+–H···O– and O–H···O– interactions. On the other hand, higher Young’s modulus values of the propane-based cocrystal compared to the macro-dimensional salicylic acid are attributed to the stronger O–H ···N hydrogen bonding. Thus, homologous alkane functional groups can influence the mechanical properties of the organic solid crystals. Additionally, in situ solid-solid polymorphic phase transformation and nucleation of a metastable and elusive polymorph of SA cocrystals in combination with 4,4’-bipyridine were studied. Understanding the solid-solid phase transformations and nucleation mechanisms are important for proper control over the parameters associated with the synthesis of targeted crystalline solids with desired crystal structure. Using in situ powder X-ray diffraction (PXRD) and terahertz time domain spectroscopy (THz-TDS) data we showed that the Form II polymorph transforms to Form I over time. AFM imaging and nanoindentation techniques were utilized to follow and quantify in real-time the solid-solid polymorphic transformation of the metastable Form II to the thermodynamically stable Form I on a single crystal basis. AFM in situ single crystal data revealed that the metastable Form II has a rod-shaped morphology and relatively high elasticity (Young’s modulus), which transforms to prism-shaped nanocrystals of much smaller sizes with significantly reduced elasticity. The AFM imaging reveals that the single crystals on the order of 80-150 nm to undergo catastrophic changes in morphology that are consistent with cracking and popping owing to a release of mechanical stress during the transformation. The nucleation mechanism for the polymorphic transformation is not spatially localized and occurs over the entire crystal surface. The higher mechanical properties of the metastable Form II is due to the presence of the additional interlayer C-H···O interactions. Furthermore, we have studied the electrical properties of boron-based cocrystals. More specifically, cocrystallization of a nonconductive 2,4-difluorophenylboronic ester catechol adduct of a 4,4’-bipyridine (BEA) host with two aromatic semiconducting guests (pyrene and tetrathiafulvalene) generated conductive cocrystals with variable charge carrier mobilities. Charge carrier mobilities of the cocrystals with either pyrene or tetrathiafulvalene were measured using conducting probe AFM (CP-AFM). The incorporation of π-rich aromatic guests through face-to-face and edge-to-face π-contacts results in electrically conductive cocrystals. The cocrystal with tetrathiafulvalene as a guest shows approximately 7 times higher charge carrier mobility than the cocrystal with pyrene. Overall, the current dissertation demonstrates the AFM-based method development and applications towards materials characterization to measure the morphological, electrical, mechanical, and phase-states at both nano- and macro-dimensions. The high spatial precision of the methods developed enables us to better understand the controlling factors for materials design and processing across nano- and macro-dimensions.
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Fay, Aurélien. "Couplage variable entre un qubit de charge et un qubit de phase." Phd thesis, Université Joseph Fourier (Grenoble), 2008. http://tel.archives-ouvertes.fr/tel-00310131.

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Nous avons étudié la dynamique quantique d'un circuit supraconducteur constitué d'un SQUID dc couplé à un transistor à paires de Cooper fortement asymétrique (ACPT). Le SQUID dc est un qubit de phase contrôlé par un courant de polarisation et un champ magnétique. L'ACPT est un qubit de charge contrôlé par un courant de polarisation, un champ magnétique et une tension de la grille.

Nous avons mesuré par spectroscopie micro-onde les premiers niveaux d'énergie du circuit couplé en fonction des paramètres de contrôle. Les mesures des états quantiques des qubits de charge et de phase sont réalisées par une mesure d'échappement du SQUID dc avec une impulsion de flux nanoseconde appliquée dans celui-ci. La mesure de l'ACPT utilise un nouveau processus quantique : l'état excité de l'ACPT est transféré adiabatiquement vers l'état excité du SQUID durant l'impulsion de flux.

Notre circuit permet de manipuler indépendamment chaque qubit tout comme il permet d'intriquer les états quantiques des deux circuits. Nous avons observé des anti-croisements des niveaux d'énergie des deux qubits lorsqu'ils sont mis en résonance. Le couplage a été mesuré sur une large gamme de fréquence, pouvant varier de 60 MHz à 1.1 GHz. Nous avons réussi à obtenir un couplage variable entre le qubit de charge et le qubit de phase. Nous avons analysé théoriquement la dynamique quantique de notre circuit. Cette analyse a permis de bien expliquer le couplage variable mesuré par une combinaison entre un couplage Josephson et un couplage capacitif entre les deux qubits.
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Guen, Eloise. "Microscopie thermique à sonde locale : Etalonnages, protocoles de mesure et applications quantitatives sur des matériaux nanostructurés." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI003.

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La microscopie thermique à sonde locale (SThM) est une technique qui permet de caractériser les propriétés thermiques de nanomatériaux et de mieux comprendre les transferts thermiques existants aux échelles sub-micrométriques. Pour correctement interpréter les mesures, les paramètres influençant le transfert thermique entre la pointe-sonde SThM et l’échantillon sont étudiés. Trois sondes résistives de SThM, se différenciant notamment par leur rayon de courbure micro ou nanométrique, sont tout d’abord caractérisées, et une méthodologie systématique de mesure en régime continu est proposée. Il est observé que la zone de sensibilité à la conductivité thermique des matériaux massifs plans est limitée à quelques W.m-1.K-1 pour toutes les pointes. Pour les matériaux les plus conducteurs, la mesure SThM est dominée par la résistance thermique de contact. Le transfert thermique par le (les) nanocontact(s) solide-solide entre la pointe et l’échantillon est dû à un transport conductif à la fois diffusif et balistique dans l’échantillon. Il est mis en évidence que la rugosité de surface impacte fortement la mesure SThM, diminuant le transfert thermique par le contact de plus de 50 % dans certains cas. Ces travaux sont mis à profit pour des caractérisations de nanomatériaux. La détermination de la conductivité thermique de couches minces de SiO2 sur substrat de silicium indique que les épaisseurs de quelques nanomètres jusqu’à 1 µm sont détectées par certaines pointes. La mesure de températures de changement de phase par microscopie SThM est également étudiée à l’aide d’un étalonnage sur des polymères massifs. L’application de cet étalonnage pour la caractérisation de couches minces de polymère confirme l’influence du substrat et de l’épaisseur de la couche sur la température déterminée par la pointe SThM. Ces travaux démontrent que la microscopie thermique permet d’obtenir des mesures quantitatives
Scanning thermal microscopy (SThM) is a technique that allows characterizing the thermal properties of nanomaterials and helps understanding heat transfer at submicron scales. To interpret the measurements, parameters influencing heat transfer between the probe and the sample are studied. Firstly, three resistive SThM probes, differing in particular by their micro and nanometric radii of curvature, are analyzed and a systematic methodology for the measurements is proposed. It is put forward that the sensitive zone to thermal conductivity of bulk planar materials is limited to few W.m-1.K-1 for the three probes. For the more conductive materials, SThM measurements are dominated by interfacial thermal resistance. Heat transfer at the solid-solid nanocontact between the probe and the sample can be both ballistic and diffusive. It is further demonstrated that surface roughness strongly impacts SThM measurements, decreasing heat transfer at the contact by more than 50 % in some cases. This work is used for characterizations of nanomaterials. The determination of the thermal conductivity of SiO2 thin film on silicon substrate indicates that thicknesses of a few nanometers up to 1 µm are detected by certain probes. Phase transition temperature measurement by SThM is also studied, using a calibration with bulk polymers. The application of this calibration for the characterization of polymer thin films demonstrates the influence of the substrate and the thin film thickness on the temperature determined by SThM. These results demonstrate that scanning thermal microscopy allows obtaining quantitative measurements
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Maaza, Malik. "Latent and thermal energy storage enhancement of silver nanowires-nitrate molten salt for concentrated solar power." University of Western Cape, 2020. http://hdl.handle.net/11394/8038.

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>Magister Scientiae - MSc
Phase change material (PCM) through latent heat of molten salt, is a convincing way for thermal energy storage in CSP applications due to its high volume density. Molten salt, with (60% NaNO3 and 40% KNO3) has been used extensively for energy storage however; the low thermal conductivity and specific heat have limited its large implementation in solar applications. For that, molten salt with the additive of silver nanowires (AgNWs) was synthesized and characterized. This research project aims to investigate the thermophysical properties enhancement of nanosalt (Mixture of molten salt and silver nanowires). The results obtained showed that by simply adjusting the temperature, Silver nanowires with high aspect ratio have been synthesized through the enhanced PVP polyol process method. SEM results revealed a network of silver nanowires and TEM results confirmed the presence of silver nanowires with an average diameter of 129 nm and 16 μm in length.
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Book chapters on the topic "NANO PHASE CHANGE"

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Wu, Liangcai, and Zhitang Song. "Phase Change Materials for Memory Application." In Advanced Nano Deposition Methods, 267–84. Weinheim, Germany: Wiley-VCH Verlag GmbH & Co. KGaA, 2016. http://dx.doi.org/10.1002/9783527696406.ch14.

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Papade, C. V., and A. B. Kanase-Patil. "Nano-Mixed Phase Change Material for Solar Cooker Application." In Engineering Optimization: Methods and Applications, 165–75. Singapore: Springer Nature Singapore, 2022. http://dx.doi.org/10.1007/978-981-19-4502-1_8.

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Kannan, K. Gopi, R. Kamatchi, and D. Dsilva Winfred Rufuss. "Potential Applications of Nano-Enhanced Phase Change Material Composites." In Composite and Composite Coatings, 233–42. New York: CRC Press, 2022. http://dx.doi.org/10.1201/9781003109723-13.

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Valance, S., M. Coref, J. Réthoré, and R. de Borsf. "Solid Phase Change Observation Using Digital Image Correlation." In Experimental Analysis of Nano and Engineering Materials and Structures, 465–66. Dordrecht: Springer Netherlands, 2007. http://dx.doi.org/10.1007/978-1-4020-6239-1_231.

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Sundararajan, Swati, and Asit B. Samui. "Smart Nano-Enhanced Organic Phase Change Materials for Thermal Energy Storage Applications." In Advanced Polymeric Systems, 3–29. New York: River Publishers, 2022. http://dx.doi.org/10.1201/9781003337058-2.

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Athikesavan, Muthu Manokar, Fausto Pedro García Márquez, Mohamed Thalib Mohamed Rafeek, and Ravishankar Sathyamurthy. "Annual Yield, Energy and Economic Analysis of Tubular Solar Stills with Phase Change Material and Nano-enhanced Phase Change Material." In Proceedings of the Fifteenth International Conference on Management Science and Engineering Management, 463–72. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-79206-0_35.

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Hayat, Muhammad Aamer, and Yong Chen. "A Brief Review on Nano Phase Change Material-Based Polymer Encapsulation for Thermal Energy Storage Systems." In Springer Proceedings in Energy, 19–26. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-63916-7_3.

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AbstractIn recent years, considerable attention has been given to phase change materials (PCMs) that is suggested as a possible medium for thermal energy storage. PCM encapsulation technology is an efficient method of enhancing thermal conductivity and solving problems of corrosion and leakage during a charging process. Moreover, nanoencapsulation of phase change materials with polymer has several benefits as a thermal energy storage media, such as small-scale, high heat transfer efficiency and large specific surface area. However, the lower thermal conductivity (TC) of PCMs hinders the thermal efficiency of the polymer based nano-capsules. This review covers the effect of polymer encapsulation on PCMs while concentrating on providing solutions related to improving the thermal efficiency of system.
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Bora, Neetu, Jaspreet Singh Aulakh, and Deepika P. Joshi. "Thermal Properties of Nano-SiO2/Paraffin Composite Phase Change Material for Thermal Energy Storage." In Green Energy and Technology, 367–74. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-2279-6_31.

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Varadaraj, Praveen Kumar, Sandeep D., Ravi Kiran N., Balaji Padya, and P. K. Jain. "Xylitol Based Phase Change Material with Graphene Nano Platelets as Fillers for Thermal Energy Management." In Learning and Analytics in Intelligent Systems, 551–58. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-24314-2_66.

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Soni, Vikram, and Arvind Kumar. "Behavior of Nano-enhanced Phase Change Material in a Spherical Thermal Battery During Unrestricted Melting." In Advances in Energy Research, Vol. 1, 309–19. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-2666-4_31.

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Conference papers on the topic "NANO PHASE CHANGE"

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Shi, L. P., T. C. Chong, X. Q. Wei, R. Zhao, W. J. Wang, H. X. Yang, H. K. Lee, et al. "Investigation of Nano-Phase Change for Phase Change Random Access Memory." In 2006 7th Annual Non-Volatile Memory Technology Symposium. IEEE, 2006. http://dx.doi.org/10.1109/nvmt.2006.378881.

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Zeng, Xie, Haifeng Hu, Yongkang Gao, Dengxin Ji, Nan Zhang, Haomin Song, Kai Liu, and Qiaoqiang Gan. "Phase change dispersion of plasmonic nano-objects." In CLEO: Applications and Technology. Washington, D.C.: OSA, 2015. http://dx.doi.org/10.1364/cleo_at.2015.jtu5a.76.

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Baris, Oksen T., and Sanjiv Sinha. "Nano-Structured Phase Change Materials and Their Calorimetry." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11799.

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Phase change materials (PCMs) store thermal energy through a phase transition. Extending the use of PCMs to transient thermal management of electronic handheld devices requires storage capacity beyond 195 kJ/m3, typical limit of a paraffin. Nano-structures can potentially increase the material choice for PCMs. Melting behavior and heat of fusion are empirically known to be altered in nano-structures. In this paper, we present thermodynamic modeling to show that confinement can lead to an enhancement in the heat of fusion of soft matter. We present material concepts that can serve as such enhanced PCMs. We also discuss modifying existing calorimetry techniques to measure the heat capacity of nanometer scale thin films of soft matter. Design and sensitivity details of nano-calorimeter are presented to analyze phase change phenomenon in ultra-thin polymer films.
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Burrow, Joshua A., Md Shah Alam, Evan M. Smith, Riad Yahiaoui, Ryan Laing, Piyush J. Shah, Thomas Searles, et al. "Reconfigurable chiral phase change nanomaterials." In CLEO: Science and Innovations. Washington, D.C.: Optica Publishing Group, 2023. http://dx.doi.org/10.1364/cleo_si.2023.sm3h.6.

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Shi, Luping. "Nano Phase Change for Data Storage and Beyond." In Joint International Symposium on Optical Memory and Optical Data Storage. Washington, D.C.: OSA, 2011. http://dx.doi.org/10.1364/isom_ods.2011.otub4.

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Zeng, Xie, Haifeng Hu, Yongkang Gao, Dengxin Ji, Nan Zhang, Haomin Song, Kai Liu, and Qiaoqiang Gan. "Revealing dispersive phase change in plasmonic nano-objects." In Frontiers in Optics. Washington, D.C.: OSA, 2015. http://dx.doi.org/10.1364/fio.2015.fm3b.5.

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Kawabata, Ken-ichi, Rei Asami, Takashi Azuma, Hideki Yoshikawa, and Shin-ichiro Umemura. "Cavitation assisted HIFU with phase-change nano droplet." In 2008 IEEE Ultrasonics Symposium (IUS). IEEE, 2008. http://dx.doi.org/10.1109/ultsym.2008.0187.

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Miao, X. S., B. J. Zeng, Z. Li, and W. L. Zhou. "Nanopatterning by phase change nanolithography." In 2012 7th IEEE International Conference on Nano/Micro Engineered and Molecular Systems (NEMS). IEEE, 2012. http://dx.doi.org/10.1109/nems.2012.6196708.

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Li, Yiming, Chih-Hong Hwang, Yi-Ting Kuo, and Hui-Wen Cheng. "Structure Effect of Cylindrical-Shaped GeSbTe Alloy on Phase Transition in Phase Change Memory." In 2008 8th IEEE Conference on Nanotechnology (NANO). IEEE, 2008. http://dx.doi.org/10.1109/nano.2008.109.

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Colburn, Shane, Alan Zhan, Sanchit Deshmukh, Jason Myers, Jesse Frantz, Eric Pop, and Arka Majumdar. "Metasurfaces Based on Nano-Patterned Phase-Change Memory Materials." In CLEO: Science and Innovations. Washington, D.C.: OSA, 2017. http://dx.doi.org/10.1364/cleo_si.2017.sm3n.6.

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Reports on the topic "NANO PHASE CHANGE"

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Wicker, Louise, and Nissim Garti. Entrapment and controlled release of nutraceuticals from double emulsions stabilized by pectin-protein hybrids. United States Department of Agriculture, October 2004. http://dx.doi.org/10.32747/2004.7695864.bard.

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Original Objectives Specific objectives are to: (1) modify charge and hydrophobicity of pectins to improve emulsion stabilizing properties (2) develop emulsions that can be sterically stabilized using modified pectins and/or pectin/protein hybrids (3) obtain submicronal inner emulsion droplets (10-50 nanometers) with small and monodispersed double emulsion (1-2 μm) droplets with long-term stability (possibly by emulsified microemulsions) and (4) trigger and control the release at will. Background Methodology for encapsulation and controlled release of selected addenda, e.g. drugs, vitamins, phytochemicals, flavors, is of major impact in the food industries. Stable double emulsions with desired solubilization and release properties of selected addenda are formed using charge modified pectin or pectin-protein hybrids. Major conclusions, solutions, achievements * We developed methodology to isolate PME isozymes and prepared modified pectins in sufficient quantity to characterize, form single and double emulsions and test stability. *Amino acid sequence of PME isozymes was estimated and will facilitate cloning of PME for commercial application * The contribution of total charge and distribution of charge of modified pectin was determined *Soluble complexes or modified pectins and whey isolates are formed * Stable W/O/W double emulsions were formed that did not cream, had small particle size * Inner phase of double emulsions are nano-sized and stable. These new structures were termed emulsified microemulsions (EME) * Release of bioactives were controlled between a few days to months depending on layering on droplets by hybrids * Commercial testing by Israeli company of stability and release of Vitamin C showed good chemical stability Implications Resolved the major stability limitation of W/O/W emulsions. Resolved the questions regarding citrus PMEs and tailored pilot scale modification of pectins.
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