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Adaptive Shape Ripening and Interparticle Bridging of L-Arginine-Stabilized Silica Nanoparticles During Evaporative Colloidal Crystal Assembly
摘要： During evaporative self-assembly of colloidal crystal films, spherical L-arginine-stabilized silica colloids adapt to different close-packed geometries by faceting and forming bridge connections with their nearest neighbors. We systematically studied the morphological changes of 37 and 138 nm diameter colloids during evaporative assembly and compared them to 65 nm St?ber silica colloids prepared without L-arginine. Colloidal crystal films were grown from particles that had been dialyzed against water or L-arginine, and tetraethylorthosilicate (TEOS) and/or L-arginine were added to solutions during colloidal film growth. Solid-state 29Si NMR spectra showed the presence of L-arginine and incompletely condensed silica in colloids grown from silica seeds in L-arginine solutions. These colloids were especially susceptible to chemical ripening during the colloidal assembly process, adopting faceted shapes that reflected the packing symmetry of the colloidal crystal films. The addition of L-arginine and TEOS accelerated these shape changes by catalyzing the hydrolysis and olation of silica, and by adding a source of silica to the solution, respectively. This chemistry provides a route to single-component and binary colloidal crystals composed of non-spherical silica building blocks.
关键词： evaporative self-assembly,colloids,silica nanoparticles,colloidal crystal,L-arginine
更新于2025-09-23 15:23:52
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Preparation of Spherical Silica with Controllable Size
摘要： The spherical silica particles were prepared by sol-gel method with TEOS as precursor, ethanol as solvent in the presence of ammonia. The effects of reaction temperature and the amount of ammonia and TEOS on the size and morphology of silica particles were investigated. The hydrolysis temperature , alkali and TEOS content does not affect the morphology of silica, the silica particles were spherical; With the increase of hydrolysis temperature, particle size of silica showed first increased and then decreased, when the hydrolysis temperature is 30 oC, the silica particle size up to 0.6 μm, when the hydrolysis temperature is 60 oC, the silica particle size is 0.15 μm; With the increase of the content of alkali, silica particle size showed first increased and then decreased, when the alkali content is 20 ml, the silica particle size up to 0.6 μm and when the alkali content is 10 ml, the silica particle size is 0.2 μm; With the increase of TEOS dosage, the amount of spherical silica increased and the particle size of silica spherical particles first increased and then decreased.
关键词： spherical,TEOS,silica
更新于2025-09-23 15:23:52
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Silica aerogel membranes fabricated using removable nitrocellulose scaffolds
摘要： Two different methods were developed to generate silica-based aerogel membranes using nitrocellulose scaffolds. The first method involved incorporating fibers of nitrocellulose (NC) into the sol prior to gelation. NC fibers were either removed using a solvent during aging or calcining after aerogel formation to produce reticulated micron-sized channels in the aerogels. In the second method, an NC lacquer was mixed with the sol, and the mixture separated into a NC-rich phase and a sol-rich phase. The NC phase was subsequently removed from the aerogel using a solvent, creating aerogels with interconnected porosity. Aerogels were prepared from tetraethyloxysilane (TEOS) as a precursor and methyltriethoxysilane (MTES) as a co-precursor. Replacing TEOS with 25 vol% MTES increased the mechanical stability, allowing for greater ease of handling. Additionally, the more open network of the MTES gels led to higher helium gas permeability than that for the pure TEOS gels.
关键词： Silica membrane,Interconnected porosity,Nitrocellulose template,Cellulose nitrate,Silica aerogel
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE 21st International Multi-Topic Conference (INMIC) - Karachi, Pakistan (2018.11.1-2018.11.2)] 2018 IEEE 21st International Multi-Topic Conference (INMIC) - Silica Nano-Particulate Coating Having Self-Cleaning and Antireflective Properties for PV Modules
摘要： In this research, silica nanoparticles are coated over the solar PV module glass to acquire super hydrophilic, antireflective and highly transparent surface. Silane precursor mixed with air sprayed on the substrate by aerosol deposition method. Pressure difference between the plasma chamber and the substrate is tuned by the introduction of helium gas, which results in good control over layer thickness and refractive indices. Due to the porous nature and graded index of coated film, the transmittance of glass substrate is increased from 91% to 99.2%. Surface topology of coated film is studied by AFM shows excellent antifogging and super-hydrophilic nature attributed to roughness and nano-porosity of coated film. Moreover, the super-hydrophilic nature endows these coatings with self-cleaning properties, which further enhances the overall efficiency of solar PV modules.
关键词： Antireflective coatings,Super-hydrophilic,Silica nanoparticles,Thin films,solar PV,Aerosol deposition,Nano-porous
更新于2025-09-23 15:22:29
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Durability and purification performance of concrete impregnated with silicate and sprayed with photocatalytic TiO2
摘要： This paper proposes an integrated concrete surface treatment with surface enhancement via silicate impregnation and surface spraying with TiO2 (a photocatalyst). In this work, two types of silicate-based materials, sodium alumina silicate (SAS) and colloidal silica (COS) were used. Various tests were carried out to characterize the silicate properties and engineering performance of the impregnated concrete. In addition, the purification performance in concrete sprayed with TiO2 was investigated. Concrete impregnated with silicate and sprayed with TiO2 showed an improvement in the durability and mechanical performance because of the addition of the CSH gel and TiO2 barrier. After impregnation, the TiO2 applied by spraying retained good performance for the removal of acetaldehyde and methyl orange.
关键词： Sodium alumina silicate,Durability performance,Purification performance,Photocatalyst,Colloidal silica
更新于2025-09-23 15:22:29
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Graphene-SiO <sub/>2</sub> Interaction from Composites to Doping
摘要： An overview of the interaction between monolayer graphene and SiO2 dielectric substrate is reported focusing on the effect this latter has on doping and strain induced by thermal treatments in controlled atmosphere. The disentanglement of strain and doping is highlighted and the comparison with another dielectric substrate of Al2O3 evidences the critical role that the substrate has in the electronic properties of graphene. The reported results pave the way for microelectronic devices based on graphene on dielectrics and for Fermi level tuning in composites of graphene and nanoparticles.
关键词： doping,graphene,silica,strain
更新于2025-09-23 15:22:29
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Polydopamine-Coated Gold Core/Hollow Mesoporous Silica Shell Particles as a Nanoplatform for Multimode Imaging and Photothermal Therapy of Tumors
摘要： It is highly desirable to develop a new hybrid nanoplatform that integrates diagnosis and treatment elements for effective theranostics of tumors. Herein, we have skillfully designed a nanoplatform of polydopamine (PDA)-coated and perfluorohexane (PFH)-filled gold core/hollow mesoporous silica shell (Au@mSiO2-PFH-PDA, ASPP for short) particles for photoacoustic (PA)/ultrasound (US)/computed tomography (CT)/thermal imaging and photothermal therapy (PTT) of tumors. In this work, we first synthesized Au seed particles with a diameter of 15.8 nm using a sodium citrate reduction method, and coated Au seeds with polyvinylpyrrolidone for further growth of solid silica shell/mesoporous silica shell onto the Au seeds. After treatment via selective etching to remove solid silica shell, amination of surface of the particles, and filling of PFH into the internal cavity of the spheres with a diameter of 182.1 nm, PDA coating was performed to render the particles with an external shell thickness of 15.1 nm. The formed hybrid particles with a size of 212.2 nm are colloidally stable and exhibit good cytocompatibility, and display excellent PA/US/CT/thermal imaging property due to the co-presence of PDA, PFH, and Au nanoparticles. Furthermore, the PDA coating renders the platform with a photothermal conversion efficiency of 61.2%, enabling effective photothermal ablation of cancer cells in vitro and a xenografted 4T1 tumor model in vivo under irradiation with an 808 nm laser. More importantly, in the primary 4T1 tumor model, intratumoral injection of the ASPP and irradiation with an 808 nm laser can also completely inhibit the occurrence lung metastasis induced by the 4T1 tumor. The as-prepared hybrid nanoplatform may hold a great promise to be adopted for multimode imaging and PTT of tumors and inhibition of tumor metastasis.
关键词： Tumor metastasis inhibition,Multimode imaging,Photothermal therapy,Polydopamine NPs,Hollow mesoporous silica,Surface modification
更新于2025-09-23 15:22:29
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Microwave transmission performance of fused silica ceramics in microwave high-temperature heating
摘要： Compared with traditional heating methods, microwave heating is widely used in many industrial heating fields because of its advantages, such as material-selective heating, volumetric heating and high-efficiency heating. However, previous studies have shown that the heating mode depends on the transmission performance of refractory insulation materials. In this study, a commonly used refractory material (fused silica ceramics) for microwave heating was studied, according to the law of electromagnetic wave propagation in a single-layer plate, the power transmission coefficient (PTC) of the material at different thickness, temperature and frequency (915 MHz and 2360 MHz) was calculated and analysed, in order to design the refractory structure which has good microwave transmission performance in the whole microwave heating process. The results show that the transmission performance of fused silica ceramics fluctuates regularly with increasing thickness, and there are several microwave transmission peaks in the PTC patterns, the thicknesses corresponding to the transmission peaks at frequency 2360 MHz are in order 0.033 m, 0.065 m and 0.098 m; as the temperature increases, the position of the transmission peaks will shift to a smaller thickness, the transmission performance of fused silica ceramics decreases slightly with increasing temperature. Comparing the transmission performance of mullite, alumina (Al2O3) and fused silica ceramics, it was found that the fused silica ceramics have excellent transmission properties; especially it is at high temperature. The results of this study can provide guidance for the selection of refractory structure materials and sizes as well as the optimization of heating process parameters in high-temperature microwave heating.
关键词： A. Microwave heating,D. Transmission performance,B. Fused silica ceramic,C. High temperature wave transmitting material
更新于2025-09-23 15:22:29
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Fabrication, Modelling and Assessment of Hybrid 1-D Elastic Fabry Perot Microcavity for Mechanical Sensing Applications
摘要： 1-D multilayer dielectric films consisting of seven pairs of SiO2 and TiO2 alternating layers are deposited on a SiO2 substrate using the radio frequency sputtering technique. The thicknesses of the film layers are chosen to reflect the visible radiation around 650 nm. An elastic microcavity layer made of Polydimethylsiloxane was sandwiched between two Bragg reflectors. A fabrication process was then developed for elastic microcavity in order to tailor the thickness, establish the surface planarity and to increase reproducibility of the samples. Optical transmittance of the single Bragg reflector and the microcavity were both simulated and measured. A comparison between measurement data and Transfer Matrix Method calculations shows a favourable correlation. Furthermore, in order to assess the suitability of the microcavity as a force sensor, transmittance measurements were carried out as a function of the applied forces. The change in the elastic microcavity thickness due to applied forces resulted in cavity resonance peak shifts proportional to the applied forces.
关键词： Optical Characterization and Modelling,Silica and Titania,1D Elastic Photonic Crystal,Mechanical Sensor,RF sputtering,PDMS
更新于2025-09-23 15:22:29
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Modeling the Compressive Behavior of Anisotropic, Nanometer-Scale Structured Silica
摘要： Recently, large plastic deformations were observed during compression testing of biotemplated, anisotropic, and hierarchically structured silica monoliths. Based on the material’s nanometer-scale structuring, a dynamic model is devised in which parallel silica struts are compressed, and sheared in longitudinal direction. The resulting interfacial shear forces lead to successive plastic deformations during cyclic loading with incrementally increasing forces, matching observations by mechanical testing. The authors report on the physical parameter values obtained from fitting model curves to measured ones, their relation to prior structural observations, and their utility to tailor the intricate mechanical behavior of this novel material.
关键词： simulation,deformation,dynamic,fracture,nanoscale,silica,brittle
更新于2025-09-23 15:22:29