Journal articles: 'High-dispersed silica'

1

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.

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Ren, Zhiming, Fei Zhang, Liwen Yue, Xuan Li, Yu Tao, Ge Zhang, Kai Wu, Cong Wang, and Baoshan Li. "Nickel nanoparticles highly dispersed in silica pillared clay as an efficient catalyst for chlorobenzene dechlorination." RSC Advances 5, no. 65 (2015): 52658–66. http://dx.doi.org/10.1039/c5ra05926g.

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A series of highly dispersed nickel nanoparticles (with a uniform size of 4.7 nm) between the lamellae of silica pillared clay was synthesized, which exhibit high catalytic performance for the hydrodechlorination of chlorobenzene.

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Ikuhara, Yumi H., Hiroshi Mori, Tomohiro Saito, and Yuji Iwamoto. "High-Temperature Hydrogen Adsorption Properties of Precursor-Derived Nickel Nanoparticle-Dispersed Amorphous Silica." Journal of the American Ceramic Society 90, no. 2 (February 2007): 546–52. http://dx.doi.org/10.1111/j.1551-2916.2006.01434.x.

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13

Tertykh, Valentin A. "Some peculiarities of the surface chemical modification of the high-dispersed silica fillers." Macromolecular Symposia 108, no. 1 (May 1996): 55–61. http://dx.doi.org/10.1002/masy.19961080106.

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Jankowska, Aleksandra, Andrzej Kowalczyk, Małgorzata Rutkowska, Włodzimierz Mozgawa, Barbara Gil, and Lucjan Chmielarz. "Silica and silica–titania intercalated MCM-36 modified with iron as catalysts for selective reduction of nitrogen oxides – the role of associated reactions." Catalysis Science & Technology 10, no. 23 (2020): 7940–54. http://dx.doi.org/10.1039/d0cy01415j.

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Fe-MCM-36 zeolites are effective catalysts for high-temperature NH₃-SCR – their activity is related to effective NO to NO₂ oxidation over Fe₂O₃ species, while high N₂-selectivity is attributed to dispersed Fe-species active in N₂O decomposition.

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Dorigato, A., LE Govaert, and A. Pegoretti. "Lifetime assessment of high-density polyethylene–silica nanocomposites." Nanomaterials and Nanotechnology 9 (January 1, 2019): 184798041984998. http://dx.doi.org/10.1177/1847980419849984.

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In this work, the effect of fumed silica on the long-term resistance of high-density polyethylene was investigated. Different amounts of functionalized fumed silica nanoparticles were dispersed in a high-density polyethylene matrix by melt compounding, and compression molded specimens were tested under tensile mode in the quasi-static ramp and creep conditions. In particular, tensile tests at different speeds and temperatures and the subsequent application of the modified Ree–Eyring model allowed the determination of an analytical expression correlating the strain rate with the yield stress and the testing temperature. It was demonstrated that the introduction of fumed silica led to a significant drop in the deformation rate, especially at elevated filler amounts. Creep tests showed that the nanofiller addition led to a progressive reduction of the critical deformation values. The application of this engineering approach evidenced how nanosilica introduction led to a systematic increase of the time-to-failure values, and good accordance between theoretical prediction and experimental measurements was found.

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Chang, Dong Sook, Yong Jae Kwon, Chang Sung Lim, Jong Won Yoon, and Kwang Bo Shim. "Fabrication of Uniformly Nano-Sized Macroporous Silica Structure Using Templates." Key Engineering Materials 317-318 (August 2006): 729–32. http://dx.doi.org/10.4028/www.scientific.net/kem.317-318.729.

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Uniformly nano-sized macroporous silica consisting of well-defined pore sizes were successfully fabricated. A modified sol-gel process, using mono-dispersed polystyrene(PS) spheres as templates, was employed for configuring three-dimensionally ordered macroporous structure. The nano-sized macroporous silica structure was formed when the templates were removed by the calcination at high temperature. The pH value affected uniformly stacked order in the PS/silica matrix due to the PS being uniformly coated by silica film at appropriate pH value. Also this pH value affected the iso-electrics points between the PS and silica particles surface charges. The heating temperatures and the reaction times were considered to conform the microstructural morphology, the thermal deposition of organic components, the matrix wall thickness and densification behavior. Three-dimensionally assembled porous silica consists of uniform-sized pores of 200nm and high specific surface area of 163 m2/g.

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17

Tanahashi, H., S. Osanai, M. Shigekuni, K. Murakami, Y. Ikeda, and S. Kohjiya. "Reinforcement of Acrylonitrile—Butadiene Rubber by Silica Generated in situ." Rubber Chemistry and Technology 71, no. 1 (March 1, 1998): 38–52. http://dx.doi.org/10.5254/1.3538470.

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Abstract In situ silica reinforcement was applied to the acrylonitrile—butadiene rubber (NBR) vulcanizates. The amount of in situ silica introduced in the NBR vulcanizates was limited due to the high polarity of NBR. The presence of γ-mercaptopropyltrimethoxysilane (γ-MPS) in the NBR vulcanizate increased the conversion of TEOS in the sol-gel reaction and resulted in the higher amount of in situ silica, compared to the system without γ-MPS. The obtained silica was very fine and dispersed very homogeneously. In situ sol-gel reaction of TEOS in the NBR vulcanizates mixed with a conventional silica (VN-3) was also carried out. The reinforcement efficiency in this system increased with the increase of the amount of mechanically mixed conventional silica. Interestingly, the hysteresis loss decreased by the in situ filling of silica.

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18

Park, Ji Chan, Jae In Kwon, Shin Wook Kang, Dong Hyun Chun, Heon Jung, Ho-Tae Lee, and Jung-Il Yang. "Highly productive cobalt nanoparticles supported on mesocellular silica foam for the Fischer–Tropsch reaction." New Journal of Chemistry 40, no. 11 (2016): 9586–92. http://dx.doi.org/10.1039/c6nj00544f.

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19

González, E. M., M. I. Montero, F. Cebollada, C. de Julián, J. L. Vicent, and J. M. González. "Magnetic properties of Ni nanoparticles dispersed in silica prepared by high-energy ball milling." Europhysics Letters (EPL) 42, no. 1 (April 1, 1998): 91–96. http://dx.doi.org/10.1209/epl/i1998-00557-x.

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Kaneko, Katsumi, and Katsuya Inouye. "Adsorption Activity of NO on Iron Oxide-Dispersed Porous Materials." Adsorption Science & Technology 5, no. 3 (September 1988): 239–50. http://dx.doi.org/10.1177/026361748800500306.

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Iron oxide-dispersed activated carbon fibers (ACF), granular activated carbons, zeolites, and silica gels have been prepared in order to develop good adsorbents for NO. The adsorption isotherms of NO on these samples have been measured at 303 K over an NO pressure range up to 80 kPa. The iron oxide-dispersed ACF samples (α- and β-ACF), obtained under the synthetic conditions employed for the preparation of α-FeOOH and β-FeOOH respectively, show very high adsorption activity for NO; their adsorption rates and capacities are much greater than those for untreated activated carbons, zeolites and silica gels. Furthermore, α- and β-ACF are effective in adsorbing NO from a 5 ppm NO/N2 gas mixture, reducing the concentration from 5 ppm to less than 1 ppm at 303 K after just one circulation with a flow velocity of 200 ml/min.

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Wang, Yan-qing, Yu Guo, Rong-xin Cui, Zhong-ming Wang, and You-liang Wu. "Preparation and mechanical properties of nano-silica/UPR polymer composite." Science and Engineering of Composite Materials 21, no. 4 (September 1, 2014): 471–77. http://dx.doi.org/10.1515/secm-2013-0051.

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AbstractThis article mainly aims at experiments used for modifying unsaturated polyester resin (UPR), and trying to enhance the strengthening and toughening performance of nano-silica/UPR polymer composite in order to improve its integrated mechanical properties and to expand its field of application. Experiments were initially used to get high dispersibility nano-silica powder by adding silane coupling agent KH570 as a dispersant into commonly and commercially available nano-silica powder. Then, high dispersibility nano-silica powder was added as a filling with different mass fraction ratios into UPR and nano-silica/UPR polymer composite samples were fabricated. Infrared spectroscopy analysis, X-ray diffraction analysis, and scanning electron microscopy (SEM) analysis were conducted for high dispersibility nano-silica powder. Mechanical properties test and SEM observation of fracture morphology were investigated for nano-silica/UPR polymer composite samples. The results revealed that adding silane coupling agent KH570 with a mass fraction ratio 3% into nano-silica powder made nano-silica best dispersed after the modification reaction at a temperature of 80°C for 2 h. When the high dispersibility nano-silica powder was added into UPR with a mass fraction ratio 1.5%, the impact strength of nano-silica/UPR polymer composite improved greatly by 9.6%. However, when the high dispersibility nano-silica powder was added into UPR with a mass fraction ratio 2%, the tensile strength, bending strength and extension rate of nano-silica/UPR polymer composite improved greatly by 152%, 102%, and 167%, respectively.

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Kamal, Mazlina Mustafa, and Dayang Habibah Abang Asmawi. "Influence of Mixing Procedure on Properties of Silica Filled Epoxidised Natural Rubber Compounds." Advanced Materials Research 1024 (August 2014): 175–78. http://dx.doi.org/10.4028/www.scientific.net/amr.1024.175.

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Since the introduction of the so-called Green Tyre concept, in the early 90ies, the use of silica as reinforcing fillers has spread and grown worldwide. The general advantages of silica as reinforcing filler over carbon black filler are better rolling resistance by achieving at least equal wet traction while tread wear should not be adversely affected. One way to obtain both low rolling resistance and high wet traction is indeed, to use precipitated silica together with solution polymers in tyre treads. The benefits of reinforcement by silane coupled silicas, in certain blends of solution styrene –butadiene rubber (SBR) and butadiene rubber (BR), were recognized by major tyre manufacturer. However, the use of silica compounds entails considerable disadvantages in terms of raw material costs and processability (before vulcanization). These difficulties include higher compound Mooney Viscosity (ML1+4) that increases upon storage, short scorch time and environmental problems related to alcohol evolution. The high viscosity and poor processability in silica filled rubber compounds are believed to be associated with silica reaggregation (self aggregation) after rubber compounding. The study has been made of the effect of increased mixing stage and dispersion agent in rubber on uncured properties of the Silica Filled Epoxidised Natural Rubber Compounds. In this experiment, two orders of mixing were considered (1) Two Stages Mixing and (2) Three Stages Mixing. Results showed that filler dispersion, Mooney Viscosity and Payne Effect was influenced by the degree of mixing. The incorporation of dispersion agents in the compounds also resultant in the similar manner. It is believed that the dispersion agent could coat the silica surfaces as they are being broken down during the mixing and then stabilize the dispersed structure by stearically preventing silica reagglomeration.

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Li, Y., M. Hariharaputhiran, and S. V. Babu. "Chemical–mechanical polishing of copper and tantalum with silica abrasives." Journal of Materials Research 16, no. 4 (April 2001): 1066–73. http://dx.doi.org/10.1557/jmr.2001.0148.

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Chemical mechanical polishing of copper and tantalum was performed using fumed amorphous silica abrasive particles dispersed in H2O2, Fe(NO3)3, and glycine solutions. Results showed that in DI water silica did not polish Cu but Ta had a relatively high polish rate. Cu polish rate decreased with increasing particle concentration in Fe(NO3)3-based slurries due to the adsorption of Fe3+ on the silica surface. Addition of H2O2 enhanced Cu polish rate but reduced Ta polish rate. The specific surface area of the particles played an important role in the removal of Ta and Cu, presumably due to some chemical bonding between the materials being polished and the silica particles.

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Chen, Lijuan, Xiaohui Guo, Yuanfang Luo, Zhixin Jia, Yongjun Chen, and Demin Jia. "Inorganic and Organic Hybrid Nanoparticles as Multifunctional Crosslinkers for Rubber Vulcanization with High-Filler Rubber Interaction." Polymers 10, no. 10 (October 12, 2018): 1138. http://dx.doi.org/10.3390/polym10101138.

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Improving the interfacial interaction between rubber and silica nanoparticles, and simultaneously reducing free sulfur and preventing migration and volatilization of a rubber vulcanizing agent, commercial sulfur compound aliphatic ether polysulfide (VA-7) was chemically attached to the silica surface to obtain a functionalized nanoparticle (silica-s-VA7). Functional nanoparticles can not only effectively crosslink rubber without sulfur as a novel vulcanizator, but are also evenly dispersed in the rubber matrix and improve the dispersion of the remaining pristine silica as an interfacial compatibilizer. In addition, the thicker immobilized polymer layer and prominent crosslinking density of SBR nanocomposites simultaneously demonstrate that the novel vulcanizing agent silica-s-VA7 gives rise to significant improvement on the rubber–filler interfacial adhesion on account of the covalent linkages of organic and inorganic interfaces between elastomer and nanofillers. We envisage that this strategy may provide a new avenue to implement high-efficiency design for a multifunctional rubber-vulcanizing agent through an organic and inorganic hybridization mechanism.

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Partch, Richard E., Yuming Xie, S. T. Oyama, and Egon Matijević. "Preparation and properties of uniform coated colloidal particles. VIII. Titanium nitride on silica." Journal of Materials Research 8, no. 8 (August 1993): 2014–18. http://dx.doi.org/10.1557/jmr.1993.2014.

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Spherical silica particles, dispersed in ethanol/water solutions, were first coated with titania by hydrolysis of added titanium isopropoxide. The coating thickness could be readily adjusted by the ratio of titanium alkoxide concentration to the amount of silica. The coated cores prepared as above were then treated with ammonia in a temperature-programmed reaction to produce a shell of titanium nitride. After nitridation, the powders of the high specific surface area showed electrical conductivity, which depended on the thickness of the coatings.

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Shishkanova, V. N., M. V. Ivanko, and Andrey Yu Kozlov. "Cullet-Filled Concrete." Materials Science Forum 992 (May 2020): 73–78. http://dx.doi.org/10.4028/www.scientific.net/msf.992.73.

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The paper considers how cullet of different particle-size distribution affects the concrete strength. Experiments have proven that large-particle cullet (1.25 cm or larger) could be used as an aggregate; the concrete strength will be on par with those of ordinary natural/crushed sand concrete. The paper proves the feasibility of injecting highly dispersed silica fume in combination with effective polycarboxylate-based superplasticizers in cullet-based concrete mixtures. Highly dispersed silica fume will positively affect the strength characteristics of concrete, as silica fume in cement rock reacts with Са (ОН)2, which is released upon the hydration of the clinker minerals С3S and С2S; the reaction produces very strong compounds. Concretes containing up to 30% silica fume in combination with a superplasticizer will feature very high early strength. Use of strong aggregates with a 30% cullet content can produce strong concretes; after steamed, a concrete containing silica fume and polycarboxylate-based superplasticizer will reach 90% of the graded strength. Cement-rock microstructure studies show that the polymer component of the STACHEMENT 2280 superplasticizer will gradually transcend from the glass grains to the cement rock. The interface between the polymer-coated glass grains and the cement rock is blurred and barely present. This strengthens the glass-rock adhesion and improves the concrete strength. This is why cullet is recommended for use in the production of curb stones.

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Luz, Ignacio, Mustapha Soukri, and Marty Lail. "Flying MOFs: polyamine-containing fluidized MOF/SiO2 hybrid materials for CO2 capture from post-combustion flue gas." Chemical Science 9, no. 20 (2018): 4589–99. http://dx.doi.org/10.1039/c7sc05372j.

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Solid-state synthesis ensures a high loading and well dispersed growth of a large collection of metal–organic framework (MOF) nanostructures within a series of commercially available mesoporous silica allowing to render MOFs into fluidized solid sorbents for CO₂ capture from post-combustion flue gas in a fluidized-bed reactor.

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Wan, Wei, Jian Yang, Yong Bao Feng, and Tai Qiu. "Mechanically Strong and Hierarchical Porous Silica Ceramics via Gelcasting-Lyophilization." Key Engineering Materials 697 (July 2016): 414–18. http://dx.doi.org/10.4028/www.scientific.net/kem.697.414.

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Highly porous silica ceramics were prepared by in-situ gelation of an aqueous suspension with well dispersed silica particles and N’N-dimethylacrylamide (DMAA) monomer, followed by lyophilization and pressureless sintering. The gelcasting process was imparted by polymerization of DMAA. The silica raw materials used in this experiment are the dusts collected from the exhaust fumes of silicon industry. The as-obtained porous silica ceramics had three-dimensional and hierarchical pore structure and the porosity ranged from 75 to 88 % as the sintering temperature varied from 850 to 1050 °C. In addition, the porous silica ceramics appeared to have strong mechanical strength. Compressive strength of the porous silica ceramics was as high as 3.2 MPa even when the porosity was nearly 80%. The gelcasting-lyophilization method was proved to be a novel and promising route for the preparation of highly porous and mechanically strong materials.

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Yang, Jie, Hongwei Zhang, Meihua Yu, Irene Emmanuelawati, Jin Zou, Zhiguo Yuan, and Chengzhong Yu. "High-Content, Well-Dispersed γ-Fe2O3Nanoparticles Encapsulated in Macroporous Silica with Superior Arsenic Removal Performance." Advanced Functional Materials 24, no. 10 (October 1, 2013): 1354–63. http://dx.doi.org/10.1002/adfm.201302561.

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Sun, Mingzhe, Aamir Hanif, Tianqi Wang, Chao Yang, Daniel C. W. Tsang, and Jin Shang. "Chrysanthemum flower like silica with highly dispersed Cu nanoparticles as a high-performance NO2 adsorbent." Journal of Hazardous Materials 418 (September 2021): 126400. http://dx.doi.org/10.1016/j.jhazmat.2021.126400.

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Dvorsky, Richard, Ladislav Svoboda, Jiří Bednář, Pavel Mančík, Dalibor Matýsek, and Marketa Pomiklová. "Deposition of Sorption and Photocatalytic Material on Nanofibers and Fabric by Controlled Sublimation." Materials Science Forum 936 (October 2018): 63–67. http://dx.doi.org/10.4028/www.scientific.net/msf.936.63.

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This paper presents a new method of deposition of photocatalytic sorbent on nanofibers. This deposition uses controlled sublimation of water molecules from the vacuum-gel that is patent-protected. Silica gel nanostructures are precipitated by heterogeneous nucleation on the surface of nanofibres from an aqueous suspension of silicate nanoparticles and semiconductor carbon nitride (C3N4) or graphene nanosheets. After rapid solidification of gel (at least 104K/s), the nanofibers coated with the silica gel dispersion C3N4, or graphene are subjected to controlled sublimation at – 41 °C. This technology produced a nanofibrous material, which is stably coated with a highly porous silicate sorbent including dispersed photocatalytic nanoparticles. This textile material has a total sorption surface area of the order of hundreds m2/g. Unlike conventional sorbents, it is capable due to dispersed photocatalytic nanoparticles to regenerate sorption capacity by the absorption of visible light. The results of the preliminary research confirmed the high application potential of new controlled sublimation technology in the production of regenerable photocatalytic sorption fabrics.

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Ren, Yanyan, Le Yang, Liuding Wang, Hui Xing, and Hongjing Wu. "Microwave Absorption Properties of Fe-Doped Ordered Mesoporous Carbon (CMK-3)/Silica Matrix Nanocomposites with Magnetic Multi-Resonance Mechanisms." Nano 10, no. 08 (November 23, 2015): 1550110. http://dx.doi.org/10.1142/s1793292015501106.

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Low-density Fe-doped ordered mesoporous carbon (CMK-3)-silica (SBA-15) nanocomposites with different Fe contents have been prepared by a catalytic carbonization procedure followed by high-temperature calcination in N2. From field emission-scanning electron microscope (FE-SEM) and high resolution-transmission electron microscope (HR-TEM) images, it can be concluded that CMK-3 particles are dispersed homogeneously into a silica matrix and form a novel, special and interesting composite nanostructure. The metal species ([Formula: see text]18[Formula: see text]nm) are dispersed on the surface of frameworks during the catalytic carbonization procedure and endow a magnetic property to the carbon–silica nanocomposites. The optimal reflection loss (RL) calculated from the measured permittivity and permeability is [Formula: see text]19[Formula: see text]dB at 17.2[Formula: see text]GHz for an absorber thickness of 2.00[Formula: see text]mm. Moreover, the electromagnetic (EM) wave absorption less than [Formula: see text]10[Formula: see text]dB is found to exceed 5.76[Formula: see text]GHz as the layer thickness is 2.37 mm. The permittivity dispersion behaviors have been explained based on the Cole–Cole model and the conductivity contribution model. A new simple empirical model was also supposed to find the fitted curves of the multi-resonance imaginary permeability spectra of the composites. The EM wave can hardly be reflected on the absorber surface because of a better match between dielectric loss and magnetic loss, which originates from the combination of dielectric carbon–silica and magnetic Fe species.

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Salimian, S., A. Zadhoush, and A. Mohammadi. "A review on new mesostructured composite materials: Part II. Characterization and properties of polymer–mesoporous silica nanocomposite." Journal of Reinforced Plastics and Composites 37, no. 11 (March 26, 2018): 738–69. http://dx.doi.org/10.1177/0731684418760205.

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Hybrid inorganic–organic materials are promising systems for a variety of applications due to their extraordinary properties with intricate composite architectures composed of nanoscale inorganic moieties with organic polymers synergistically intertwined to provide both useful functionality and mechanical integrity. These materials have a high potential for future applications and therefore attract considerable interest in polymer science research during the last years. Among the various explored inorganic nanostructures, the mesoporous silica has been considered as a fascinating material to construct novel ordered and well-dispersed nanocomposites due to their high surface areas, periodic and size-controllable pore channels. This review is written with the intention to give an overview of the characterization and material properties of polymer–mesoporous silica nanocomposites. Among polymer–mesoporous silica composites, various categories including polyaniline, polypyrrole, polystyrene, polypropylene, polyethylene, epoxy, rubber, and acrylate polymer were discussed in detail.

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Rentería-Tapia, Víctor, Jorge A. García-Macedo, and Guadalupe Valverde-Aguilar. "Stability of Gold Nanoparticles in Sol - Gel Silica Films." Journal of Nano Research 3 (October 2008): 115–22. http://dx.doi.org/10.4028/www.scientific.net/jnanor.3.115.

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Sol-gel silica films containing gold ions were prepared with and without citric acid (capping agent). Heat treatment of these films in hydrogen atmosphere (reducing agent) leads to the formation of gold nanoparticles. The experimental optical spectra of the gold nanoparticles prepared with citric acid revealed a surface plasmon resonance band located at 585 nm. Transmission electronic microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) measurements revealed the formation of prolate gold nanoparticles (6.4 nm of average diameter) and aggregates dispersed in silica matrix. On the other hand, gold nanoparticles in sol-gel silica films prepared without citric acid exhibited a splitting in surface plasmon resonance band for the prolate gold nanoparticles with an average size <12 nm. On further annealing the samples in oxygen atmosphere, the gold nanoparticles prepared with citric acid exhibited high stability in contrast to the samples prepared without citric acid. This stability probably depends on the formation of a microporous structure of silica produced by the citric acid. The optical properties of the metallic nanoparticles were modeled using Gans theory.

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Савченко and D. Savchenko. "Investigation of Genotoxicity and Cytotoxicity of Nanocomposite Highly Dispersed Silica with Silver Nanoparticles." Journal of New Medical Technologies 20, no. 4 (December 20, 2013): 44–47. http://dx.doi.org/10.12737/2725.

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Provision of high efficiency and quality of drugs developed on the basis of nanotechnology is possible only under the requirements for the development, research, production and introduction of new pharmacological agents. Determination of genotoxicity and cytotoxicity is the first stage of toxicological studies of newly synthetized substances, the aim of which is to determine the ability to induce primary DNA and cell cultures damages. Such studies provide information about primary toxic effects of substances and constitute a basis for confirming the safety of new drugs. Considering a constant need for the introduction of new antimicrobial agents for treatment of intestinal infections, it is expedient to develop combinative drugs which will have better efficacy and safety. Significant scientific and practical interest has study of drugs based on nanosilver, which is active against antibiotic-resistant microorganisms. By the Department of Pharmacology and Clinical Pharmacology of Bogomoletz National Medical University and Chuiko Institute of Surface Chemistry NAS of Ukraine was specifically designed and synthesized nanocomposite highly dispersed silica with silver nanoparticles, which is considered as a promising drug with a complex of antibacterial and sorption-detoxication properties. The purpose of this work is to study the cytotoxicity and genotoxicity of nanocomposite highly dispersed silica with silver nanoparticles. The degree of DNA damage by nanocomposite was studied by alkaline gel electrophoresis of isolated cell test culture CHO-Kl. Investigation of cytotoxicity was carried out on passaged eukaryotic cell culture of human epidermoid carcinoma larynx (Hep-2). It is shown that nanocomposite highly dispersed silica with silver nanoparticles does not have genotoxic properties, and its cytotoxicity disappears at concentrations below 0,007%.

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Wang, Guang Hai, Yue Zhang, and Yu Feng Chen. "Silica Coatings Pigmented with Core-Shell Particles for High-Temperature Radiation Heat Shields." Key Engineering Materials 512-515 (June 2012): 1074–77. http://dx.doi.org/10.4028/www.scientific.net/kem.512-515.1074.

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Hollow glass micro-beads uniformly coated by a shell of titania with thickness of 50 to 300 nm, were fabricated by wet chemical methods. The pigments were dispersed in silica coatings，then the pigmented coatings were deposited on quartz substrates by sol-gel spin-coating method with a thickness of about 80 µm. SEM, TEM and FT-IR techniques were used to characterize the microstructure and properties of the coatings. FT-IR indicated average infrared transmittance of coatings containing the core-shell particles was significantly lower than that of coatings containing no functional particles or containing hollow glass micro-beads, when the volume fraction of core-shell particles was just 5%. In view of its low infrared transmittance, pigmented silica coatings may find applications in high-temperature heat-insulating materials for reducing radiation heat transfer.

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Zhao, Xinyu, Gaobo Yu, Jiacheng Li, Yuhong Feng, Lei Zhang, Yang Peng, Yiyuan Tang, and Longzheng Wang. "Eco-Friendly Pickering Emulsion Stabilized by Silica Nanoparticles Dispersed with High-Molecular-Weight Amphiphilic Alginate Derivatives." ACS Sustainable Chemistry & Engineering 6, no. 3 (January 17, 2018): 4105–14. http://dx.doi.org/10.1021/acssuschemeng.7b04508.

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Yang, Mengmeng, Ting Chen, Lingchong Wang, Lihua Chen, Junsong Li, and Liuqing Di. "High dispersed phyto-phospholipid complex/TPGS 1000 with mesoporous silica to enhance oral bioavailability of tanshinol." Colloids and Surfaces B: Biointerfaces 170 (October 2018): 187–93. http://dx.doi.org/10.1016/j.colsurfb.2018.06.013.

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Chee, Kai Ling, Noor Asmawati Mohd Zabidi, and Mohan Sinnathambi Chandra. "Synthesis of Cobalt Nano Particles on Silica Support Using the Strong Electrostatic Adsorption (SEA) Method." Defect and Diffusion Forum 312-315 (April 2011): 370–75. http://dx.doi.org/10.4028/www.scientific.net/ddf.312-315.370.

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Supported cobalt is one of the common catalysts used in Fischer-Tropsch synthesis (FTS). Strong electrostatic adsorption (SEA) was employed to synthesize cobalt nano particles supported on silica. Cobalt nitrate was used as the catalyst precursor and non-porous silica spheres, which were synthesized using the modified Stöber method, were used as a catalyst support. Point of zero charge (PZC) for silica was determined using equilibrium pH at high oxide loading (EpHL) method. The optimum pH was determined by measuring cobalt uptake versus pH. High cobalt uptake at basic pH and low cobalt uptake at acidic pH indicates electrostatic interaction between the cobalt complexes in the precursor solution and the hydroxyl group on the support’s surface. Catalysts prepared at optimum pH were characterized using TPR, XPS and TEM. TPR shows reduction peak at high temperature (587°C) indicating strong interaction between cobalt and silica support. XPS shows presence of Co2+ species on the surface. TEM images of the Co/SiO2 at 5 wt% and 10 wt% cobalt loadings show fairly well-dispersed cobalt oxide nano particles on the spherical silica support with narrow particle size distribution. The findings suggest that SEA was deemed a suitable method to prepare supported cobalt catalysts.

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Park, Juwoon, Kyuchul Shin, Jong-Won Lee, Huen Lee, and Yutaek Seo. "In situ Raman and 13C NMR spectroscopic analysis of gas hydrates formed in confined water: application to natural gas capture." Canadian Journal of Chemistry 93, no. 9 (September 2015): 1035–42. http://dx.doi.org/10.1139/cjc-2014-0536.

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This study investigates the formation characteristics of gas hydrate from bulk water as well as dispersed water in silica gel and dry water particles when they are exposed to natural gas. The inclusion process of methane, ethane, and propane molecules in hydrate cages were observed with in situ Raman spectroscopy, and the resulting cage occupancies were estimated from 13C NMR spectra. A high-pressure autoclave was used to monitor the formation process to determine hydrate onset time, initial growth rate, and conversion ratio. The obtained data from Raman spectra and gas consumption profiles suggested that hydrate formed within less than 20 min when the temperature is sufficiently lower than the hydrate equilibrium condition at a given pressure. Methane molecules started to occupy the small cages of structure II, but about 6 min later ethane and propane were also included in hydrate cages. 13C NMR spectroscopy confirms that only 23% of large cages of structure II are occupied by methane molecules when hydrate formed from dispersed water in silica gel, which was much less than 68% from dry water. These results suggest that the dispersion of water in silica gel and dry water would enhance the formation process by increasing gas-to-water ratio, although the composition of hydrate phase may vary depending on the formation condition. However the formation of hydrate in silica gel and dry water still provide an effective option to capture the natural gas without using complex rotating machineries.

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Perez, A., M. Treilleux, T. Capra, and D. L. Griscom. "Precipitation phenomena in high-dose iron-implanted silica and annealing behavior." Journal of Materials Research 2, no. 6 (December 1987): 910–17. http://dx.doi.org/10.1557/jmr.1987.0910.

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The effects of high-dose iron implantation into high-purity fused silica have been investigated by conversion-electron Mössbauer spectroscopy, transmission electron microscopy, Rutherford backscattering, and optical spectroscopy. In addition to isolated Fe2+ ions, samples subjected to doses of 4⊠1016 and 6 ⊠ 1016 ions cm−2 were found to contain homogeneously dispersed, equidimensional, crystalline particles ⋍2 nm, similar to Fe3O4. Precipitated spherical particles of metallic α-Fe⋍4 nm were observed in samples receiving a dose of ⋍ 1017 ions cm−2; as the dose was raised to 2.5 ⊠ 1017 ions cm−2 the mean size of these particles reached ⋍ 30 nm. Annealing in air to 800°C resulted in the growth of acicular grains of α-Fe2O3 ⋍ 20–300 nm. The optical spectra of the implanted layers are compared with the predictions of small particle theory.

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Akhtar, US, MK Hossain, MS Miran, and MYA Mollah. "Synthesis and characterization of porous silica and polyaniline-porous silica composite materials with high surface area." Bangladesh Journal of Scientific and Industrial Research 49, no. 1 (May 8, 2014): 1–8. http://dx.doi.org/10.3329/bjsir.v49i1.18847.

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Porous silica materials were synthesized from tetraethyl orthosilicate (TEOS) using Pluronic P123 (non-ionic triblock copolymer, EO20PO70O20) as template under acidic conditions which was then used to prepare polyaniline (PAni) and porous silica composites (PAnisilica) at a fixed molar ratio. These materials were characterized by nitrogen adsorption-desorption isotherm measured by Barrett-Joyner- Halenda (BJH) method and pore size distribution from desorption branch and surface area measured by the Brunauer-Emmett-Teller (BET) method, scanning electron microscopy (SEM), transmission electron microscopy (TEM), TEM-energy dispersive X-ray (EDX) and Fourier transform infrared (FT-IR) spectroscopy. The composite maintains its structure even after the polymerization and the polymer is dispersed on the inorganic matrix. The rod-like porous silica was about 1?m to 1.5 ?m long and on an average the diameter was in the range of 300- 500 nm. The SEM and TEM images show well ordered 2d hexagonal pore, high specific surface area (850 m2g-1) and uniform pore size of ca. 6.5 nm in diameter. After incorporation of PAni inside the silica pore, framework of porous silica did not collapse and the surface area of the composite was as high as 434 m2g-1 which was 5.5 time higher than our previous report of 78.3 m2g-1. Due to shrinkage of the framework during the incorporation of aniline inside the silica, the pore diameter slightly increase to 7.5 nm but still showing Type IV isotherm and typical hysteresis loop H1 implying a uniform cylindrical pore geometry. DOI: http://dx.doi.org/10.3329/bjsir.v49i1.18847 Bangladesh J. Sci. Ind. Res. 49(1), 1-8, 2014

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Wells, Vivienne, Asim Riaz, Qiming Sun, Xian Li, Ning Yan, Chi-Hwa Wang, and Wojciech Lipiński. "Mesoporous silica-encaged ultrafine ceria–nickel hydroxide nanocatalysts for solar thermochemical dry methane reforming." Applied Physics Letters 120, no. 14 (April 4, 2022): 143905. http://dx.doi.org/10.1063/5.0082365.

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Reforming of methane to produce synthesis gas for the Fischer–Tropsch process provides an alternative to fossil fuels. Silica-encaged ceria–nickel hydroxide catalysts were produced by an in situ synthesis method to obtain ultrafine bimetallic species dispersed evenly within the mesoporous silica matrix. Dry reforming and reduction-oxidation cycling was undertaken with the materials. Catalysts with high content of nickel showed good activity during dry reforming, with conversions rates close to equilibrium in equimolar conditions. Insignificant deactivation of the catalysts was observed over 5 h and 50 h of reaction at 900 °C. Syngas production via reduction–oxidation cycling was shown to be insignificant as compared to continuous catalytic reforming.

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Bok, Goseong, Gayoung Lim, Mingi Kwak, and Youngmin Kim. "Super-Toughened Fumed-Silica-Reinforced Thiol-Epoxy Composites Containing Epoxide-Terminated Polydimethylsiloxanes." International Journal of Molecular Sciences 22, no. 15 (July 28, 2021): 8097. http://dx.doi.org/10.3390/ijms22158097.

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In response to the demand for high-performance materials, epoxy thermosetting and its composites are widely used in various industries. However, their poor toughness, resulting from the high crosslinking density of the epoxy network, must be improved to expand their application to the manufacturing of flexible products. In this study, ductile epoxy thermosetting was produced using thiol compounds with functionalities of 2 and 3 as curing agents. The mechanical properties of the epoxy were further enhanced by incorporating fumed silica into it. To increase the filler dispersion, epoxide-terminated polydimethylsiloxane was synthesized and used as a composite component. Thanks to the polysiloxane–silica interaction, the nanosilica was uniformly dispersed in the epoxy composites, and their mechanical properties improved with increasing fumed silica content up to 5 phr (parts per hundred parts of epoxy resin). The toughness and impact strength of the composite containing 5 phr nanosilica were 517 (±13) MJ/m3 and 69.8 (±1.3) KJ/m2, respectively.

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Ikuhara, Yumi H., Tomohiro Saito, Yukichi Sasaki, Seiji Takahashi, and Tsukasa Hirayama. "Determination of reversible hydrogen adsorption site in Ni-nanoparticle-dispersed amorphous silica for hydrogenseparation at high temperature." Journal of Materials Research 25, no. 10 (October 2010): 2008–14. http://dx.doi.org/10.1557/jmr.2010.0254.

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The reversible hydrogen adsorption site in Ni-nanoparticle-dispersed amorphous silica (Si-O) was identified by analyzing the hydrogen adsorption behavior and the microstructure. The total amount of reversibly adsorbed hydrogen was evaluated from the total surface area of Ni and the Ni concentration in the composite. The total surface area of the Ni nanoparticles in each sample powder was calculated from the mean particle size of the Ni nanoparticles in the Si-O matrix using dark field images taken by transmission electron microscopy and high-angle annular dark-field images by scanning transmission electron microscopy. The estimated amount of reversibly adsorbed hydrogen was highly consistent with that obtained experimentally by hydrogen adsorption analysis, which suggested that reversible hydrogen adsorption occurred at the Ni/Si-O interface.

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Fu, Xin. "Polyethylenimine-Silica Mesoporous Hybrid: A Novel Adsorbent for CO2 Capture." Advanced Composites Letters 21, no. 2 (March 2012): 096369351202100. http://dx.doi.org/10.1177/096369351202100201.

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A facile pathway has been developed to synthesize polyethylenimine-modified mesoporous hybrid materials with highly efficient CO2 capturer. It is the special feature of this pathway that there are no surfactants introduced and the amine guest can be dispersed within the channels of the silica materials during the hydrolysis and polycondensation process. The obtained materials exhibit high specific surface areas, high porosity and high CO2 uptake. The amount of polyethylenimine (PEI) has important effect on the surface area, pore size and CO2 adsorption capacity of the adsorbents. For the sample containing 50 wt% PEI, the adsorbent exhibits a high adsorption capacity of 186.6 mg/g-PEI, and in situ FTIR show that CO2 is sorbed on amine sites through the formation of alkylammonium carbamates. The adsorbed CO2 could be desorbed completely from the sample at 150 °C. Moreover, the adsorbents show a stable cyclic adsorption-desorption performance.

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Yun, Kyong Ku, Jong Beom Kim, Chang Seok Song, Mohammad Shakhawat Hossain, and Seungyeon Han. "Rheological Behavior of High-Performance Shotcrete Mixtures Containing Colloidal Silica and Silica Fume Using the Bingham Model." Materials 15, no. 2 (January 6, 2022): 428. http://dx.doi.org/10.3390/ma15020428.

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There have been numerous studies on shotcrete based on strength and durability. However, few studies have been conducted on rheological characteristics, which are very important parameters for evaluating the pumpability and shootability of shotcrete. In those studies, silica fume has been generally used as a mineral admixture to simultaneously enhance the strength, durability, pumpability, and shootability of shotcrete. Silica fume is well-known to significantly increase the viscosity of a mixture and to prevent material sliding at the receiving surface when used in shotcrete mixtures. However, the use of silica fume in shotcrete increases the possibility of plastic shrinkage cracking owing to its very high fineness, and further, silica fume increases the cost of manufacturing the shotcrete mixture because of its cost and handling. Colloidal silica is a new material in which nano-silica is dispersed in water, and it could solve the above-mentioned problems. The purpose of this research is to develop high-performance shotcrete with appropriate levels of strength and workability as well as use colloidal silica for normal structures without a tunnel structure. Thereafter, the workability of shotcrete with colloidal silica (2, 3, and 4%) was evaluated with a particle size of 10 nm and silica fume replacement (4 and 7%) of cement. In this study, an air-entraining agent for producing high-performance shotcrete was also used. The rheological properties of fresh shotcrete mixtures were estimated using an ICAR rheometer and the measured rheological parameters such as flow resistance and torque viscosity were correlated with the workability and shootability. More appropriate results will be focusing on the Bingham model properties such that the main focus here is to compare all data using the Bingham model and its performance. The pumpability, shootability, and build-up thickness characteristics were also evaluated for the performance of the shotcrete. This research mainly focuses on the Bingham model for absolute value because it creates an exact linear line in a graphical analysis, which provides more appropriate results for measuring the shotcrete performance rather than ICAR rheometer relative data.

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Fu, Lipei, Jiahui Zhu, Weiqiu Huang, Jie Fang, Xianhang Sun, Xinya Wang, and Kaili Liao. "Preparation of Nano-Porous Carbon-Silica Composites and Its Adsorption Capacity to Volatile Organic Compounds." Processes 8, no. 3 (March 23, 2020): 372. http://dx.doi.org/10.3390/pr8030372.

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Carbon-silica composites with nanoporous structures were synthesized for the adsorption of volatile organic compounds (VOCs), taking tetraethyl orthosilicate (TEOS) as the silicon source and activated carbon powder as the carbon source. The preparation conditions were as follows: the pH of the reaction system was 5.5, the hydrophobic modification time was 50 h, and the dosage of activated carbon was 2 wt%. Infrared spectrum analysis showed that the activated carbon was dispersed in the pores of aerogel to form the carbon-silica composites material. The static adsorption experiments, dynamic adsorption-desorption experiments, and regeneration experiments show that the prepared carbon-silica composites have microporous and mesoporous structures, the adsorption capacity for n-hexane is better than that of conventional hydrophobic silica gel, and the desorption performance is better than that of activated carbon. It still has a high retention rate of adsorption capacity after multiple adsorption-desorption cycles. The prepared carbon-silica composites material has good industrial application prospects in oil vapor recovery, providing a new alternative for solving organic waste gas pollution.

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Liu, Kaikai, Yuanyuan Shang, Liu Yang, and Aihua Du. "Silica/GO hybrids reinforced NR: Better interface interaction and dynamic behavior." Journal of Elastomers & Plastics 52, no. 7 (September 24, 2019): 575–92. http://dx.doi.org/10.1177/0095244319877671.

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With silica firstly modified by 3-aminopropyl-triethoxysilane (APES), graphene oxide (GO) was prepared by modified Hummer’s method. APES-silica/GO (AsGO) hybrids were fabricated through hydrogen bond to reduce the polarity of silica and GO and increase the compatibility between natural rubber (NR) and AsGO. Subsequently, AsGO was incorporated into NR latex. The interaction between GO and silica in AsGO was characterized by X-ray diffraction, Raman, and Zeta potential. It was confirmed by transmission electron microscopy that the silica was uniformly dispersed on the surface of the GO. The filler–rubber interfacial interaction was thoroughly investigated. The amount of constrained region was quantified through differential scanning calorimetry results, and it showed that the high volume fraction of constrained region is responsible for the strong interfacial interaction. Besides, the mechanical performance, dynamic property, and electrical and thermal conductivity of NR-AsG x were studied. The results showed that the overall performance of NR-AsG x has an optimum value when the GO loading is 1.5 phr, which is due to the good filler dispersion and strong interface interaction.

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Kim, Tae-Gon, Young Woon Kim, Jong Soon Kim, and Byungwoo Park. "Silver-nanoparticle dispersion from the consolidation of Ag-attached silica colloid." Journal of Materials Research 19, no. 5 (May 2004): 1400–1407. http://dx.doi.org/10.1557/jmr.2004.0187.

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Silver nanoparticles dispersed in a silica matrix were made by the consolidation of a Ag-attached silica colloid, which was synthesized via the electrolysis of a pure Ag electrode, the reduction of Ag+ ions by H2, and the nucleation and growth of Ag particles on the silica nanoparticles in water. This simple process produced Ag/silica nanocomposites with a high concentration and narrow size distribution of nanoparticles, which was confirmed by transmission electron microscopy and x-ray diffraction. As estimated by Raman and photoluminescence measurements, the quantity of broken oxygen bonds was increased with increasing Ag concentration due to the intervention of Ag ions as structural modifiers in the silica network structure. Ag ions in the matrix are probably a residue of the Ag+ ions that could not be reduced by H2 during the electrolysis/reduction reaction. The optical-absorption spectra and the HCl-soaking test suggested that a chemical-interface damping effect, which was caused by electron transfer from the metal particles to the oxide matrix, dominates the optical-absorption properties in this system.

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Journal articles on the topic 'High-dispersed silica'

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