Academic literature on the topic 'High-dispersed silica'
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Journal articles on the topic "High-dispersed silica"
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Chernyshenko, T. M. "ACTION OF HIGH-DISPERSED SILICA." Biotechnologia Acta 6, no. 1 (2013): 81–85. http://dx.doi.org/10.15407/biotech6.01.081.
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Turov, V. V. "HYDRATION FEATURES OF COMPOSITE SYSTEMS BASED ON HIGH-DISPERSED SILICA AND SUCROSE IN DIFFERENT MEDIA." Biotechnologia Acta 10, no. 5 (October 2017): 51–62. http://dx.doi.org/10.15407/biotech10.05.051.
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Zhu, Gui Ru, Li Wang, Duo Wang, and Cong Jie Gao. "Synthesis of Highly Mono-Dispersed Mesoporous Silica Spheres." Advanced Materials Research 148-149 (October 2010): 967–73. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.967.
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Mono-dispersed mesoporous silica spheres with highly ordered hexagonal regularity were synthesized by hydrothermal method with tetraethoxysilane (TEOS) as silica source, cetyltrimethylammonium chloride (C16TAC) as template, methanol as co-solvent, and sodium hydroxide as alkali source. The influence of the C16TAC concentration, TEOS concentration, methanol/water ratio and the synthesis temperature on morphology and mesostructure of the prepared silica particles were investigated in detail. The results showed that the synthesized mono-dispersed spherical silica particles have ordered hexagonal mesoporous structure, high specific surface area and uniform pore size distribution.
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Bittner, M., and M. Kreuzer. "Silica Dispersed Nematics and Cholesterics for Bistable High Resolution Displays." Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals 282, no. 1 (May 1996): 373–86. http://dx.doi.org/10.1080/10587259608037591.
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Yoo, Jeseung, Yongbeom Kim, Suyong Kwon, Joohyun Lee, and Young-Soo Seo. "Surge-Resistant Nanocomposite Enameled Wire Using Silica Nanoparticles with Binary Chemical Compositions on the Surface." Journal of Nanomaterials 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/231672.
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We developed polyesterimide (PEI) nanocomposite enameled wires using surface-modified silica nanoparticles with binary chemical compositions on the surface. The modification was done using silanes assisted by ultrasound, which facilitated high density modification. Two different trimethoxysilanes were chosen for the modification on the basis of resemblance of chemical compositions on the silica surface to PEI varnish. The surface-modified silica was well dispersed in PEI varnish, which was confirmed by optical observation and viscosity measurement. The glass transition temperature of the silica-PEI nanocomposite increased with the silica content. The silica-dispersed PEI varnish was then used for enameled wire fabrication. The silica-PEI nanocomposite enameled wire exhibited a much longer lifetime compared to that of neat PEI enameled wire in partial discharge conditions.
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Cai, Weiping, Ye Zhang, and Lide Zhang. "Synthesis and luminescence of the nanosized Ce-doped silica particles dispersed within the pores of mesoporous silica host." Journal of Materials Research 14, no. 5 (May 1999): 1922–27. http://dx.doi.org/10.1557/jmr.1999.0258.
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Nanosized Ce-doped silica particles (without and with Al addition) dispersed within pores of mesoporous silica host were synthesized by soaking and sol-gel technique. It was found that the dispersed phosphor particles are mainly located within the pores that are less than 4 nm in diameter. There exist two luminescence peaks at about 350 and 700 nm, respectively, for this phosphor in the dispersed or aggregated state. For the dispersed system, the luminescence intensities of both peaks are more than 14 times higher than those of the aggregated one, the shoulders on the lower sides of the luminescence peaks disappear, and no effect of Al addition on the luminescence occurs which is in contrast to the aggregated system. This is mainly attributed to the high dispersity of nanosized phosphor particles in the host and the effective avoidance of a clustering of Ce3+ ions.
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Rasselet, Damien, Monica Francesca Pucci, Anne-Sophie Caro-Bretelle, José-Marie Lopez-Cuesta, and Aurélie Taguet. "Peculiar Morphologies Obtained for 80/20 PLA/PA11 Blend with Small Amounts of Fumed Silica." Nanomaterials 11, no. 7 (June 29, 2021): 1721. http://dx.doi.org/10.3390/nano11071721.
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This work highlights the possibility of obtaining peculiar morphologies by adding fumed silica into 80/20 polylactic acid/polyamide11 (PLA/PA11) blends. Two kinds of fumed silica (A200 and trimethoxyoctylsilane modified R805 fumed silica) were dispersed (by twin-screw extrusion, TSE) at a weight amount of 5% in neat PLA, neat PA11 and a 80/20 PLA/PA11 blend. Thermal Gravimetric Analysis (TGA) was used to verify this 5 wt % amount. Oscillatory shear rheology tests were conducted on all the formulations: (1) on neat polymer nanocomposites (PLASi5, PLASiR5, PA11Si5, PA11SiR5); and (2) on polymer blend nanocomposites (PLA80Si5 and PLA80SiR5). Scanning Electron Microscope (SEM), Scanning Transmission Electron Microscope (STEM), Atomic Force Microscopy (AFM) characterizations and laser granulometry were conducted. Microscopic analysis performed on polymer blend nanocomposites evidenced a localization of A200 silica in the PA11 dispersed phase and R805 silica at the PLA/PA11 interface. Frequency sweep tests on neat polymer nanocomposites revealed a pronounced gel-like behavior for PLASi5 and PA11SiR5, evidencing a high dispersion of A200 in PLA and R805 in PA11. A yield behavior was also evidenced for both PLA80Si5 and PLA80SiR5 blends. For the blend nanocomposites, PA11 dispersed phases were elongated in the presence of A200 silica and a quasi-co-continuous morphology was observed for PLA80Si5, whereas PLA80SiR5 exhibits bridges of silica nanoparticles between the PA11 dispersed phases.
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Xiang, Minglin, and Juan Zou. "Highly Dispersed α-MoC1-x in Porous Silica for CO Hydrogenation." Journal of Catalysts 2013 (October 24, 2013): 1–7. http://dx.doi.org/10.1155/2013/725970.
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A facile method has been developed to prepare highly dispersed α-MoC1-x in porous silica. By utilizing C atoms in methyl modified silica supports, α-MoC1-x/SiO2 was obtained via insitu carburization. The obtained samples exhibited high activity for CO hydrogenation.
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Yang, Mengnan, Zhaoli Yan, Tiantian Li, Bing Liu, Qiangshan Jing, and Peng Liu. "Role of microporous Janus silica nanosheets in the assembly of ultra-small Ag nanoparticles with high catalytic activity." Dalton Transactions 50, no. 1 (2021): 208–16. http://dx.doi.org/10.1039/d0dt03702h.
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Negatively charged surface hydroxyls and micropores of Janus silica nanosheets play a particular role in the highly efficient and dispersed assembly of ultra-small Ag nanoparticles with high catalytic activity.
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Wang, Bin, Jian-Feng Chen, and Yi Zhang. "Synthesis of highly dispersed cobalt catalyst for hydroformylation of 1-hexene." RSC Advances 5, no. 29 (2015): 22300–22304. http://dx.doi.org/10.1039/c4ra17035k.
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A highly dispersed Co–Ru/SiO2(EG) catalyst, prepared by surface modification of a silica support, exhibited significantly high activity and yield of oxygenates in 1-hexene hydroformylation.
Dissertations / Theses on the topic "High-dispersed silica"
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Каташов, Степан Олександрович. "Сорбція пробіотичних культур ентеросорбентами на основі високодисперсного кремнезему." Master's thesis, КПІ ім. Ігоря Сікорського, 2019. https://ela.kpi.ua/handle/123456789/39676.
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Магістерська дисертація: с., 22 рис., 17 табл., 81 посилання.
Важливим фактором ефективності пробіотикотерапії є виживаність клітин у шлунково-кишковому тракті та їх інтеграція в біоплівку кишечника. Тому набуло актуальності створення комбінованих препаратів з іммобілізованими культурами. Метою цієї роботи було дослідження впливу сорбції пробіотичних культур на гідро- та ксерогелі препарату «Ентеросгель» та на препараті «Силлард П». Об’єкт досліджень: комплекс сорбент-пробіотик. Предмет досліджень: виживаність пробіотичних культур після сорбції на ентеросорбентах на основі високодисперсного кремнезему. Методи досліджень: мікробіологічні.
Показано та візуалізовано сорбцію пробіотичних культур на гідро- та ксерогелі препарату «Ентеросгель» та на препараті «Силлард П»; спостерігали кращу сорбцію культури на вологому препараті, що пояснюється гідрофобністю сухого препарату.
Визначено, що іммобілізація на ентеросгелі спричиняла меншу загибель клітин, ніж на високодисперсному сухому порошку Силлард П. Встановлено, що виживаність іммобілізованих і не іммобілізованих зразків Lactobacillus plantarum після зберігання в протягом 30 діб у холодильнику за температури +4 оС зменшилась на 22 - 32 %. Ліофільне висушування призводило до зменшення виживаності на 2 порядки.
Визначено раціональні співвідношення «сорбент-суспендована культура» після сорбції: від 0,1 г/см3 до 0,15 г/см3 суспензії культури для сухого та для вологого ентеросгелю.
Встановлено позитивний вплив додавання висушеної бактеріальної целюлози на виживаність клітин, сорбованих та несорбованих на ентеросгелі, на 20-30 %, що потребує подальших досліджень.
Розроблено стартап-проект препарату «Ентероплантарум».The master’s thesis: 80 pages, 22 pictures, 17 tables, 81 references. The work is devoted to sorption of probiotic cultures by enterosorbents based on fine silica. Topicality: Probiotics, prebiotics and synbiotics are used to correct intestinal microbiocenosis. An important factor in the effectiveness of probiotic therapy is the survival of cells in the gastrointestinal tract and their integration into the gut biofilm. Therefore, the creation of combination preparations with immobilized cultures became relevant. The purpose of this study was to investigate the effect of sorption of probiotic cultures on the hydro- and xerogels of Enterosgel and Sillard P. In this work, the sorption of probiotic cultures on the hydro- and xerogels of the Enterosgel preparation and the Sillard P preparation is shown and visualized; Better sorption of the culture on the wet preparation was observed, which is explained by the hydrophobicity of the dry xerogel. It was determined that immobilization on enterosgel caused less cell death than on the highly dispersed dry powder Sillard P. It was found that the survival of immobilized and non-immobilized Lactobacillus plantarum specimens after storage for 30 days in a refrigerator at +4 C was reduced by22-32%. Freeze drying resulted in a 2-fold decrease in survival. The rational ratios of "sorbent-suspended culture" after sorption were determined: from 0.1 g / cm3 to 0.15 g / cm3 of the culture suspension for dry and wet enterosgel. The positive effect of the addition of dried bacterial cellulose on the survival of cells adsorbed and unorbed on enterosgel was found to be 20-30%, which needs further research. Start-up project of Enteroplantarum dietary supplement production developed
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chen, Yung-ji, and 陳永基. "Preparation and Characterization of Nano-Dispersed Silica Sol Solution with High Solids Content." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/uts6jr.
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碩士國立臺灣科技大學
化學工程系
100
Abstract The objective of this study is to preparing and characterizing the homogeneous aqueous of silica sol with nanoparticles. It used sodium silicate solution (water glass) as the starting monomer with the solvent of ultrapure water to proceed ion-exchange reaction by strongly acidic cation exchange resin (Amberlite® IR120), then obtained the stably nano-dispersed silica sol solution. This study also investigated such as the amount of the initiator, heat process, the pH of the aqueous silica sol, the ratio of SiO2 to Na2O and the presence of inhibitor (TMA hydroxide) and coupling agent (A187) with different variables to influence such as the particle size and distribution of aqueous silica sol, silica solid content and the stability of the long period. And then find out the best optimal process when add into coupling agent achieving efficiency. Therefore, we can derive the tendency and extent of the condensed process from these factors. The final result showed the pH value and the ratio of SiO2 to Na2O of silica sol that in the most stable range was 8 to 10.5 and 30 to 70, as well as pH approach to 8 that acquire the maximum value of the ratio of SiO2 to Na2O and the zeta potential on the particles to constitute the stability and dispersion. The silica sol solution could be further via concentrated method to obtain the higher elevations of silica solid content that achieved at 35 % to 40% as the maximum and the particle size with less than 50 nm.
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Liao, Ke-Lun, and 廖克綸. "Preparation and Characterization of Nano-Dispersed Silica Sol Solution with High Solids Content by Ion-Exchange Method." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/29831651408782661759.
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碩士國立臺灣科技大學
化學工程系
99
The objective of this study is to preparing and characterizing the homogeneous aqueous of silica sol with nanoparticles. It used sodium silicate solution (water glass) as the starting monomer with the solvent of ultrapure water to proceed ion-exchange reaction by strongly acidic cation exchange resin (Amberlite® IR120), then obtained the stably nano-dispersed silica sol solution. This study also investigated such as the amount of the initiator, the pH of the aqueous silica sol, the ratio of SiO2 to Na2O and the presence of inhibitor (TMA hydroxide) with different variables to influence such as the particle size and distribution of aqueous silica sol, silica solid content and the stability of the long period. Therefore, we can derive the tendency and extent of the condensed process from these factors. In addition, the manner of resin regenerate procedure was involved in this thesis to deal with the used cation exchange resin to be renewed availability then applied that to manufacture the aqueous silica sol in nanoscale. Furthermore, the difference about the basic property of the silica sol regenerate solution such as the particle size and distribution, pH value and silica solid content, etc., that between the precursory samples was discussed and authenticated the results of the identification whether that conform to the expectative theory. The final result showed the pH value and the ratio of SiO2 to Na2O of silica sol that in the most stable range was 8 to 10.5 and 30 to 70, as well as pH approach to 8 that acquire the maximum value of the ratio of SiO2 to Na2O and the zeta potential on the particles to constitute the stability and dispersion. The silica sol solution could be further via concentrated method to obtain the higher elevations of silica solid content that achieved to 35 % as the maximum and the particle size with less than 50 nm.
Book chapters on the topic "High-dispersed silica"
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Wada, Masashi, Kazumi Kashiwagi, Satoshi Kitaoka, and Yoshio Fuwa. "Tribological Characteristics of Carbon Nano-Fiber Dispersed Silicon Nitride Based Composites in High-Temperature Fuel." In SiAlONs and Non-oxides, 239–40. Stafa: Trans Tech Publications Ltd., 2008. http://dx.doi.org/10.4028/3-908454-00-x.239.
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Cavosie, Aaron J., and Luigi Folco. "Shock-twinned zircon in ejecta from the 45-m-diameter Kamil crater in southern Egypt." In Large Meteorite Impacts and Planetary Evolution VI. Geological Society of America, 2021. http://dx.doi.org/10.1130/2021.2550(17).
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ABSTRACT With an age of less than ~5000 yr and a diameter of 45 m, Kamil crater in Egypt is one of the youngest and smallest terrestrial impact craters known to date. Abundant evidence of shock-deformed sandstone has been reported from Kamil crater, including shatter cones, vesicular impact glass, high-pressure polymorphs of silica and car bon, planar deformation features (PDFs) and planar fractures (PFs) in quartz, dissociated zircon, melt veins, and intergranular melt, giving rise to a range of estimated shock pressures from ~20 to ~60 GPa. Here, we investigated shocked zircon from Kamil crater through characterization of microstructures in a centimeter-sized clast of shocked nonporous sandstone ejecta, previously described as containing quartz grains with PDFs and PFs, coesite, stishovite, diamond, and lechatelierite. Orientation analysis by electron backscatter diffraction (EBSD) showed that the quartz arenite consists of damaged detrital quartz grains surrounded by a matrix of either comminuted quartz or intergranular melt. Individual quartz grains are pervasively fractured (abundant PFs and PDFs); apparent isotropic crushing resulted in uniformly and highly dispersed orientation clusters on pole figures. Zircon grains are not abundant; however, four of 19 grains analyzed by EBSD contained {112} deformation twin lamellae, with individual lamellae ranging in length from 1 to 2 µm. Lengths of twin lamellae in Kamil zircon grains are anomalously short compared to those report-ed in shocked zircon from other impact structures, where individual lamellae are tens of micrometers long. Previous empirical studies have suggested that {112} twin lamellae in zircon form at ~20 GPa in non-porous target rocks, a finding supported by their coexistence, in some impactites, with high-pressure phases such as reidite. The only available experimental constraint, by diamond anvil cell, found {112} twins in zircon powder quenched at 20 GPa. The presence of coesite, stishovite, lechatelierite, and shocked quartz with PDFs in the studied sample is consistent with empirically derived pressure estimates of ~20 GPa for {112} twin formation in zircon in the ejecta sample from Kamil crater. Kamil thus represents the smallest and youngest impact structure where shock-twinned zircon has been reported. Given the apparent efficiency of {112} twin formation (21% of grains), shock-twinned zircon is here shown to provide a robust and readily identifiable record of shock deformation in a relatively common mineral at one of the smallest known terrestrial impact craters.
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Taber, Douglass F. "Best Synthetic Methods: Reduction." In Organic Synthesis. Oxford University Press, 2013. http://dx.doi.org/10.1093/oso/9780199965724.003.0008.
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Heshmatollah Alinezhad of Mazandaran University, Iran. developed (Tetrahedron Lett. 2009, 50, 659) the reagent 3, a white powder that is stable for many months, as a hydride donor for the reductive amination of aldehydes and ketones. Jean-Marc Campagne of the Institut Charles Gephardt Montpellier established (Synlett 2009, 276) a simple microwave protocol for reducing aldehydes and ketones to the corresponding hydrocarbons that looks general enough to become the method of choice for this important transformation. Joanne E. Harvey of Victoria University of Wellington, in the course of a total synthesis of Aigialomycind D, observed (J. Org. Chem. 2009, 74, 2271) that despite the high reactivity of the monosubstituted alkene of 7, the conjugated alkene could be selectively reduced. Brian S. Bodnar of SiGNa Chemistry described (J. Org. Chem. 2009, 74, 2598) a simple procedure for the reduction of an ester such as 9 to the alcohol 10, using Na dispersed on silica gel. Takao Ikariya of the Tokyo Institute of Technology designed (Angew. Chem. Int. Ed. 2009, 48, 1324) a Ru complex for the hydrogenation of N-acylsulfonamides and N-acylcarbamates such as 11 to the corresponding alcohol, 12. Remarkably, Hideo Nagashima of Kyushu University demonstrated (Chem. Commun. 2009, 1574) that even in the presence of the ester, the amide of 13 could be selectively reduced to the enamine 14. The enamine could be hydrolyzed to the aldehyde or reduced to the amine, but it is also an activated intermediate, for instance, for Michael addition to ethyl acrylate or methyl vinyl ketone. Diimide (HN=NH) is a useful reagent for selective reduction, as illustrated by the conversion of 15 to 17 . David R. Carbery of the University of Bath devised (J. Org. Chem. 2009, 74, 3186) a convenient procedure for the in situ generation of diimide from 16 and hydrazine hydrate. The reductive cleavage of tertiary nitriles to the corresponding hydrocarbon under dissolving metal conditions has been known for some time (J. Org. Chem. 1996, 61, 4219). Reduction of secondary nitriles required more forcing conditions, with K metal and crown ether (Tetrahedron Lett. 1985, 26, 6103).
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Anton Okhai, Timothy, Azeez O. Idris, Usisipho Feleni, and Lukas W. Snyman. "Nanomaterial-Enhanced Receptor Technology for Silicon On-Chip Biosensing Application." In Biosensor - Current and Novel Strategies for Biosensing [Working Title]. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.94249.
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Nanomaterials integration in biosensors designs are known to enhance sensing and signaling capabilities by exhibiting remarkably high surface area enhancement and intrinsic reactivity owing to their distinctive optical, chemical, electrical and catalytic properties. We present the synthesis and characterization of silver nanoparticles (AgNPs), and their immobilization on a silicon on-chip biosensor platform to enhance sensing capability for prostate specific antigen (PSA) - cancer biomarkers. Several techniques, including UV-Visible (UV-Vis) absorption spectrum, Fourier transforms infrared spectroscopy (FTIR), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM) and field emission scanning electron microscopy (FESEM) were used for characterizing the AgNPs. The biochemical sensor consists of AgNPs immobilized on the receptor layer of a silicon avalanche mode light emitting device (Si AM LED) which enables on-chip optical detection biological analytes. A bio-interaction layer etched from the chip interacts with the evanescent field of a micro dimensioned waveguide. An array of detectors below the receptor cavity selectively monitor reflected light in the UV, visible, infrared and far infrared wavelength regions. AgNPs used as an immobilization layer in the receptor layer enhances selective absorption analytes, causing a change in detection signal as a function of propagation wavelength as light is dispersed. The analytes could range from gases to cancer biomarkers like prostate specific antigen.
Conference papers on the topic "High-dispersed silica"
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Shin, Donghyun, Byeongnam Jo, Hyun-eun Kwak, and Debjyoti Banerjee. "Investigation of High Temperature Nanofluids for Solar Thermal Power Conversion and Storage Applications." In 2010 14th International Heat Transfer Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/ihtc14-23296.
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The aim of this study is to investigate the enhancement of thermal properties of various high temperature nanofluids for solar thermal energy storage application. In concentrating solar power (CSP) systems, the thermo-physical properties of the heat transfer fluids (HTF) and the thermal energy storage (TES) materials are key to enhancing the overall system efficiency. Molten salts, such as alkali nitrates, alkali carbonates, or eutectics are considered as alternatives to conventional HTF to extend the capabilities of CSP. However, there is limited usage of molten salt eutectics as the HTF material, since the heat capacity of the molten salts are lower than that of conventional HTF. Nanofluid is a mixture of a solvent and nanoparticles. Well dispersed nanoparticles can be used to enhance thermo-physical properties of HTF. In this study, silica (SiO2) and alumina (Al2O3) nanoparticles as well as carbon nanotubes (CNT) were dispersed into a molten salt and a commercially available HTF. The specific heat capacity of the nanofluids were measured and applicability of such nanofluid materials for solar thermal storage applications were explored. Measurements performed using the carbonate eutectics and commercial HTF that are doped with inorganic and organic nano-particles show specific heat capacity enhancements exceeding 5–20% at concentrations of 0.05% to 2.0% by weight. Dimensional analyses and computer simulations were performed to predict the enhancement of thermal properties of the nanofluids. The computational studies were performed using Molecular Dynamics (MD) simulations.
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Gavrielatos, Ilias, Ramin Dabirian, Ram S. Mohan, and Ovadia Shoham. "Separation Kinetics of Oil/Water Emulsions Stabilized by Nanoparticles." In ASME 2017 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/fedsm2017-69112.
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A state-of-the-art, Portable Dispersion Characterization Rig (P-DCR) is used to investigate the effect of nanoparticles on oil-water emulsion formation and stabilization. Mineral oil and distilled water are used as the test fluids and separation profiles are obtained from the experiments using a sophisticated software. Spherical silica nanoparticles of average primary particle size of 20 nm were selected as the emulsifying agent, since silica is commonly found in the produced fluids. Nanoparticles of different wettabilities were used to investigate their effect on separation kinetics of solid stabilized emulsions in terms of solid particle concentration, wettability, initial dispersion phase, water-cut, and shearing time. In one series of experiments the emulsions were prepared with intermediate-wet nanoparticles. Both simple water-in-oil (W/O), as well as multiple oil-in-water-in-oil (O/W/O) emulsions were observed. Faster separation occurred when the particles were initially dispersed in oil. Increased nanoparticle concentration, as well as shearing time typically resulted in slower emulsion separation rates. Another series of experiments was performed with hydrophobic and hydrophilic nanoparticles. Very fast separation rates were observed when using hydrophilic silica nanoparticles and 25% water-cut regardless of solid concentration. However, when the water-cut was increased to 50% and 75% very stable emulsions were produced. Emulsions prepared using hydrophobic particles were the most stable across all water-cuts. For the case of 25% water-cut, no water coalescence was observed for a wide range of oil-wet nanoparticle concentrations. Oil creaming was promoted as the concentration of solids decreased, and the emulsions remained oil continuous and highly resistant to water coalescence even for very low solid concentration (100 ppm), resulting in a dispersed phase volume fraction as high as 93%. The effect of nanoparticles on the properties of pure fluids, namely, density, viscosity and surface/interfacial tension is also reported. The main findings of the study include the following: Nanoparticles, even at low concentrations, can significantly decrease separation rates of oil and water emulsions. The Portable Dispersion Characterization Rig (P-DCR) is recommended as an effective way to measure emulsion stability in the field.
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Titinchi, Salam J. J., Waheed Saban, Leslie Petrik, and Hanna S. Abbo. "Synthesis, Characterization and Physiochemical Properties of Platinum Supported on Mesoporous Carbon." In ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology collocated with ASME 2011 5th International Conference on Energy Sustainability. ASMEDC, 2011. http://dx.doi.org/10.1115/fuelcell2011-54670.
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Ordered mesoporous carbon (OMC) has been prepared by impregnating the pores of the silica template (SBA-15) with liquid petroleum gas (LPG) or sucrose. The desired support (OMC) was obtained after dissolution with NaOH. Platinum nanoparticles were dispersed on ordered mesoporous carbons using Chemical Vapour Deposition (CVD) method and Pt(acac)2 as metal source. The resulting ordered mesoporous carbon possess a large surface area with high microporosity, and a controlled pore size distribution, High-quality carbon replicas of SBA-15 show an X-ray diffraction peak at low angle, which indicates that the structural periodicity of the (111) planes has been maintained. Their pore volume and specific surface area are high and the pore volume is almost entirely microporous. The synthesized Pt/OMC was characterized by powder X-Ray diffraction, HR-TEM, HR-SEM, EDS, thermogravimetric analysis, and nitrogen adsorption. The performance of Pt catalyst supported OMC was evaluated by electrochemical studies, which shows almost similar activity to the commercial catalyst.
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Gupta, Amit, Xuan Wu, and Ranganathan Kumar. "Possible Mechanisms for Thermal Conductivity Enhancement in Nanofluids." In ASME 4th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2006. http://dx.doi.org/10.1115/icnmm2006-96220.
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This study discusses the merits of various physical mechanisms that are responsible for enhancing the heat transfer in nanofluids. Experimental studies have cemented the claim that ‘seeding’ liquids with nanoparticles can increase the thermal conductivity of the nanofluid by up to 40% for metallic and oxide nanoparticles dispersed in a base liquid. Experiments have also shown that the rise in conductivity of the nanofluid is highly dependent on the size and concentration of the nanoparticles. On the theoretical side, traditional models like Maxwell or Hamilton-Crosser models cannot explain this unusually high heat transfer. Several mechanisms have been postulated in the literature such as Brownian motion, thermal diffusion in nanoparticles and thermal interaction of nanoparticles with the surrounding fluid, the formation of an ordered liquid layer on the surface of the nanoparticle and microconvection. This study concentrates on 3 possible mechanisms: Brownian dynamics, microconvection and lattice vibration of nanoparticles in the fluid. By considering two nanofluids, copper particles dispersed in ethylene glycol, and silica in water, it is determined that translational Brownian motion of the nanoparticles, presence of an interparticle potential and the microconvection heat transfer are mechanisms that play only a smaller role in the enhancement of thermal conductivity. On the other hand, the lattice vibrations, determined by molecular dynamics simulations show a great deal of promise in increasing the thermal conductivity by as much as 23%. In a simplistic sense, the lattice vibration can be regarded as a means to simulate the phononic transport from solid to liquid at the interface.
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Yang, Hongjoo, and Debjyoti Banerjee. "Study of Specific Heat Capacity Enhancement of Molten Salt Nanomaterials for Solar Thermal Energy Storage (TES)." 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/mnhmt2012-75338.
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The overall thermal efficiency of solar power plants is highly sensitive to the operating characteristics of the Thermal Energy Storage (TES) devices. Enhancing the operating temperature of TES is imperative for enhancing the thermal efficacy of solar power plants. However, material property limitations for high temperature operation severely limit the choice of materials for TES. Molten salts and their eutectics are promising candidates for high temperature operation of TES. To enhance the thermal and operational efficiency of TES, the thermo-physical properties such as the specific heat capacity and thermal conductivity of the materials need to be maximized. The specific heat capacity (Cp) of molten salt is relatively smaller than other conventional TES materials. Recent studies have shown that addition of nanoparticles to molten salts can significantly enhance their specific heat capacity. Several transport and energy storage mechanisms have been proposed to account for these enhancements. Primarily, the layering of solvent molecules due to inter-molecular forces (due to competition between adhesive and cohesive forces) is observed at solid-liquid interface, leading to the formation of a more dense or “compressed layer” of solvent molecules on the dispersed nanoparticles. The formation and existence of the compressed layer has been demonstrated experimentally and from numerical predictions (e.g., Molecular Dynamics/ MD models). To verify the enhancement of specific heat capacity of molten salt nanofluids, the influence of compressed layer has been explored in this study. This implies that for the same amount (or concentration) of nanoparticle, the ratio of surface/volume of the individual nanoparticles can change significantly depending on the nanoparticles size and shape — which in turn can affect the mass fraction of the compressed layer formed on the surface of the nanoparticles. In this study, the specific heat capacity of the molten salt nanomaterials was investigated for: (a) silica nanoparticles in eutectic mixture of alkali chloride salt eutectics, and (b) silica nanoparticles in an eutectic mixture of alkali carbonate salts eutectics. The effect of the particle size distribution was considered in this study and it was observed that smaller nanoparticles contribute a larger proportion to the observed specific heat capacity enhancements. The size of distribution of the nanoparticles in the molten salt mixture/ nanomaterial (nanocomposites and nanofluids) was measured by using Scanning Electron Microscopy (SEM), and subsequently the actual number of nanoparticles (as a function of size) that were dispersed in molten salt fluid was calculated. The specific heat capacity of molten salt nanomaterial was calculated using a classical mixing model and by accounting for the contribution from the compressed layer in the mixture.
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Wu, Xuan, Ranganathan Kumar, and Parveen Sachdeva. "Calculation of Thermal Conductivity in Nanofluids From Atomic-Scale Simulations." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-80849.
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Nanofluids that consist of nanometer sized particles and fibers dispersed in base liquids have shown the potential to enhance the heat transfer performance. Although three features of nanofluids including anomalously high thermal conductivities at very low nanoparticle concentrations, strongly temperature dependent thermal conductivity and significant increases in critical heat flux have been studied widely, and layering of liquid molecules at the particle-liquid interface, ballistic nature of heat transport in nanoparticles, and nanoparticle clustering are considered as the possible causations responsible for such kind of heat transfer enhancement, few research work from atomic-scale has been done to verify or explain those fascinating features of nanofluids. In this paper, a molecular dynamic model, which incorporates the atomic interactions for silica by BKS potential with a SPC/E model for water, has been established. To ensure the authenticity of our model, the position of each atom in the nanoparticle is derived by the crystallographic method. The interfacial interactions between the nanoparticle and water are simplified as the sum of interaction between many ions. Due to the electrostatic interaction, the ions on the nanoparticle’s surface can attract a certain number of water molecules, therefore, the effect of interaction between the nanoparticle and water on heat transfer enhancement in nanofluids is studied. By using Green-Kubo equations which set a bridge between thermal conductivity and time autocorrelation function of the heat current, a model which may derive thermal conductivity of dilute nanofluids that consist of silica nanoparticles and pure water is built. Several simulation results have been provided which can reveal the possible mechanism of heat enhancement in nanofluids.
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Matsuda, Keisuke, Yusuke Ozawa, and Takayuki Saito. "Newly Developed Two-Tip Optical-Fiber Probe for Accurate Measurement of High-Speed Micro-Droplets: Simultaneous Measurement of Their Velocities and Diameters." In 17th International Conference on Nuclear Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/icone17-75358.
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Optical fiber probing is very useful and reliable for bubbles/droplets measurement particularly in the gas-liquid two-phase flows that have dense dispersed phase and are impossible to be measured via usual visualization techniques. For the practical purpose of small- or medium-size bubbles/droplets measurement, one of the authors successfully developed a Four-Tip Optical-fiber Probe (F-TOP) and reported their excellent performance in industrial uses. Recently, particular demands for measuring properties of micro bubbles/droplets have increased in researches on multi-phase flows. However, no one succeeded in simultaneously measuring diameters and velocities of high-speed micro-droplets (velocity > 50 m/s; 50 μm < diameter < 500 μm). We made a challenge of measuring such tiny droplets via newly developed optical fiber probe equipped with two tips (Two-Tip Optical-fiber Probe: T-TOP). We have succeeded in this difficult measurement with it. Each optical fiber probe composing the T-TOP is made of a silica optical fiber (125 μm in external diameter, 50 μm in core diameter, 37.5 μm in clad thickness). The optical fiber was fine-drawn using a micro pipette puller, and this yielded a sub-μm-scale tip. The interval of the fiber axes and the gap of the tips were arranged depending on the droplets diameter range. In this paper, we demonstrate the performance of the T-TOP. First, we confirm its practicality in industrial use. The strength of the T-TOP is confirmed by exposure test of high-velocity and high-temperature steam flows. Second, we consider the influence of the flow on the measurement of T-TOP; the optical noise due to probe vibration by the high-velocity gas flow around the T-TOP is considered. Next, we confirm its performance using an orifice-type nozzle (300 μm < droplets diameter < 500 μm; droplets velocities < 40 m/s). We confirm the performance of the T-TOP; the results of T-TOP are compared with those of the visualization of the droplets by using an ultra-high-speed video camera. At the same time, we consider the process of droplet contact with the T-TOP via visualization of ultra-high-speed video camera.
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Hatchell, Daniel, Wen Song, and Hugh Daigle. "Effect of Inter-Particle Van Der Waals Attraction on the Stability of Pickering Emulsions in Brine." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/206112-ms.
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Abstract Pickering emulsions are stabilized by solid particles that occupy the fluid-fluid interface, physically preventing coalescence. Their stability in brine, where interparticle electrostatic repulsion is negligible and van der Waals (vdW) attraction dominates, makes them attractive for applications in porous media. Recent studies postulate that inter-droplet particle networks assemble in brine and aid Pickering emulsion stability to coalescence. This work experimentally assesses the effect of increasing interparticle vdW attraction on particle network strength and emulsion stability. We grafted 6 nm, 12 nm, and 20 nm silica nanoparticles with varying densities of polyethylene glycol (PEG) to prevent aggregation and dispersed them in either brine or deionized water (DI). We characterized the PEG-coated nanoparticles with thermogravimetric analysis and dynamic light scattering to determine PEG grafting density, diameter, and zeta potential. To generate oil-in-water emulsions, we sonicated dispersions of variable nanoparticle concentration and decane in equal volumes. We imaged the emulsions with microscopy and centrifuged them for 15 minutes at 5000 g of acceleration, using the volume of decane released after centrifugation as a measurement of emulsion coalescence to the applied force. Nanoparticle characterization confirmed successful grafting of PEG to the silica surface. We compared trends in emulsion stability as a function of salinity and particle diameter to changes in the relevant interparticle forces described by extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Analysis of microscopy images showed an increase in emulsion droplet diameter with decreasing nanoparticle concentration, salinity, and increasing nanoparticle diameter. Through centrifugation we observed that lower PEG grafting densities tended to produce more stable emulsions, suggesting that particles with high grafting densities and consequently high steric repulsion tended to repel and prevent formation of strong particle networks. Emulsions generated in DI coalesced more easily, indicating that electrostatic repulsion dominated relative to vdW attraction and that particle networks did not form. In brine, where electrostatic forces were screened out by counterions, the emulsions better resisted coalescence, consistent with the formation of a particle network. The strength of the network was inferred from the difference in emulsion stability to coalescence in DI and in brine. We measured a greater brine-DI stability difference of 3.7× for the larger 20 nm PEG-coated nanoparticles, compared with 3.3× and 2.2× for the 12 nm and 6 nm PEG-coated particles, respectively, further supporting the role of particle networks on emulsion stability.
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Yegin, Cengiz, Cenk Temizel, and Mustafa Akbulut. "Solvent-Loaded Microspheres for Permeability Enhancement in Heavy Crude Oil Reservoirs." In SPE Annual Technical Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/205991-ms.
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ABSTRACT With their abundancy and high-quality, it is predicted that fossil fuels will remain as the main resource that will meet the global energy demand in the several upcoming decades. Developments in hydrocarbon recovery technologies, both from conventional and unconventional reservoirs, have substantially contributed to the overall production levels in recent years. However, recovery factors obtained by using the current methods are still considered to be insufficient, and the companies have been looking for new materials and methods to enhance the efficiency and amount of recovery. One of the major issues related to low recovery factors is low permeability of reservoirs. Existence of blockages in pore throats and high level of heterogeneity lowers the mobility of hydrocarbons. In this study, we discuss development of an innovative material to be used as an additive in reservoir injection fluids to remove pore blockages in order to enhance the recovery levels. This additive material is made of pressure-sensitive microspheres loaded with solvents, which can (i) easily disperse in the injection fluid and travel to the low-permeability regions, (ii) break under pressure and confinement to release solvents, and (iii) remove blockages by targeting surroundings, especially asphalt-based particles and grains. This approach relies on the breakage of microcapsules in the confined region and release of the solvents to target blockages in porous media. In other words, the developed microspheres improve permeability of reservoirs as a result of pressure- and confinement-dependent breakage and release of solvents. Preparation of these microspheres was achieved by the encapsulation of solvent (toluene) emulsions in silica-based solid shells. Structure and stability of the solvent-loaded microspheres were examined using a variety of analytical techniques including UV-vis spectroscopy, optical microscopy, scanning electron microscope (SEM) and dynamic light scattering (DLS). It was found that the prepared microspheres possessed smooth surfaces with shell thicknesses in the range of 100-150 nm. Additionally, sand column tests were performed to evaluate the recovery potential of injection fluids in presence of solvent-loaded microspheres. It was shown that the use of solvent encapsulated in microspheres doubled the recovery factor of heavy oil compared to that of free solvent dispersed in the injection fluid. Such enhancement in the recovery factor was related to the release of solvents in localized areas, i.e., confined regions, as a consequence of breakage of microspheres. This novel approach of delivering solvents to low-permeability regions provides a significant driving force to eliminate pore blockages to facilitate mobilization of hydrocarbons trapped in confined spaces.
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Chinnakurli Suryanarayana, Ramesh, Saleem Khan, Praveennath G. Koppad, and Zulfiqar Khan. "Tribological Behaviour of Hot Extruded Al6061-Si3N4 Composite." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64459.
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Silicon nitride (Si3N4) possesses excellent hot hardness, wear resistance coupled with good corrosion resistance. Further, it possesses high anti friction properties making it an ideal reinforcement in developing high quality light weight, metal matrix composites for tribological applications. Silicon nitride has been successfully dispersed in aluminum alloy matrices. Their tribological properties with the beneficial effect of silicon nitride in enhancing the wear resistance of metal matrix composite have been reported by several researchers. Most of the researchers have focused on development of silicon nitride reinforced aluminum composite by powder metallurgy and casting route. However, meager information is available as regards the secondary processing of these composites in particular hot extrusion. Several researchers have reported an improved tribological behaviour in composites after extrusion. Hot extrusion of light weight metal matrix composites is very challenging. In the light of the above, this paper discusses the tribological behaviour of hot extruded Al6061 aluminum composites, which were initially developed by stir casting technique. Nickel coated silicon nitride particles were dispersed in Al6061 alloy using stir casting process. The cast composites were extruded at an extrusion ratio of 1:10 adopting a temperature of 550°C. The hot extruded composite (6Wt% Si3N4) and the matrix alloy were subjected to metallographic studies, microhardness and friction and wear tests using a pin on disc machine. Friction and wear test were carried out at loads ranging from 10 to 60 N at a sliding velocity of 0.314m/s. The worn surfaces and wear debris analysis have been carried out to understand the mechanism of wear in the developed hot extruded composites. The developed hot extruded composites exhibited lower coefficient of friction and wear rates when compared with matrix alloy.
Reports on the topic "High-dispersed silica"
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Asenath-Smith, Emily, Ross Lieblappen, Susan Taylor, Reed Winter, Terry Melendy, Robert Moser, and Robert Haehnel. Observation of crack arrest in ice by high aspect ratio particles during uniaxial compression. Engineer Research and Development Center (U.S.), February 2022. http://dx.doi.org/10.21079/11681/43145.
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In nature, ice frequently contains dissolved solutes or entrapped particles, which modify the microstructure and mechanical properties of ice. Seeking to understand the effect of particle shape and geometry on the mechanical properties of ice, we performed experiments on ice containing 15 wt% silica spheres or rods. Unique to this work was the use of 3-D microstructural imaging in a -10ºC cold room during compressive loading of the sample. The silica particles were present in the ice microstructure as randomly dispersed aggregates within grains and at grain boundaries. While cracks originated in particle-free regions in both sphere- and rod-containing samples, the propagation of cracks was quite different in each type of sample. Cracks propagated uninhibited through aggregates of spherical particles but were observed to arrest at and propagate around aggregates of rods. These results imply that spherical particles do not inhibit grain boundary sliding or increase viscous drag. On the other hand, silica rods were found to span grains, thereby pinning together the microstructure of ice during loading. These results provide insights into mechanisms that can be leveraged to strengthen ice.