Relevant bibliographies by topics / Silica microspheres

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers
  6. Reports

Academic literature on the topic 'Silica microspheres'

Author: Grafiati
Published: 4 June 2021
Last updated: 5 February 2022

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Journal articles on the topic "Silica microspheres"

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Zhou, Sen, Xu Jian Li, Yong Juan Shi, and Chun Jie Yan. "Preparation of Monodisperse Functional Polystyrene/Silica Microsphere Composite via Suspension Polymerization Method." Applied Mechanics and Materials 470 (December 2013): 66–69. http://dx.doi.org/10.4028/www.scientific.net/amm.470.66.

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The monodisperse functional Polystyrene/Silica (PS/silica) microsphere has been successfully prepared via suspension polymerization followed by the modified silica composite phenylethylene method. The FTIR, SEM, EDS and BEI were used to characterize the structure and composition of monodisperse functional PS/Silica microspheres. The results indicated that the dosage of silica modifier affect the compatibility of the modified silica and phenyl ethylene. The several modified silica would synergistically impact on the morphology and performance of products corresponding to distinguish formation mechanisms. The thermal stability and compressive strength performance had been improved compared with polystyrene (PS).The weight loss of PS/Silica microspheres were less than polystyrene (PS) which weightlessness ratio is 96.92 wt %. The compressive strength of PS/Silica microspheres was almost two times as many as pure PS microspheres. The formation mechanism of monodisperse functional PS/Silica microsphere was developed ahead according to the results of FTIR, SEM, EDS and BEI under various polymerization conditions.
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Chimonides, G. F., J. M. Behrendt, E. Chundoo, C. Bland, A. V. Hine, A. Devitt, D. A. Nagel, and A. J. Sutherland. "Cellular uptake of ribonuclease A-functionalised core–shell silica microspheres." J. Mater. Chem. B 2, no. 42 (2014): 7307–15. http://dx.doi.org/10.1039/c4tb01130a.

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Protein transduction: core–shell microspheres have been synthesised and coupled to ribonuclease A. Cellular uptake of these microspheres causes significantly reduced levels of intracellular RNA and reduced cell viability demonstrating that core–shell microsphere-mediated delivery of active enzymes into cells is effective.
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Ma, Guang Hui, Fa Ai Zhang, and Chang Sheng Gu. "Preparation of Polymer Microspheres Using Silane Coupling Agent Modified Nano-SiO2 as Single Stabilizer." Advanced Materials Research 341-342 (September 2011): 247–51. http://dx.doi.org/10.4028/www.scientific.net/amr.341-342.247.

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This paper demonstrates that silica nanoparticles were modified by the four silane coupling agents (KH-151, KH-550, KH-560, KH-570) firstly, then polystyrene/silica (PS/SiO2) composite microsphere with PS core and silica nanoparticles shell were prepared by Pickering emulsion polymerization. The characterization of optical microscope (OM), scanning electron microscope (SEM), and thermogravimetic analysis ( TGA) illustrates that these microsphere are composed of PS and silica nanoparticles. Silica nanoparticles modified by the different silane coupling agents could form the stable PS/SiO2 microsphere over 70 °C, while the unmodified silica nanoparticles are difficult to form stable PS/SiO2 microspheres at the same temperature. The PS/KH-151-SiO2 microsphere exhibits the least average particle size, while the PS/KH-570-SiO2 microsphere produces the largest. Both SEM and TGA confirm that microsphere surface exists solid nanoparticles.
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Kim, Young, Dong Lee, Eun Jung, Jun Bae, Sang Lee, Hyeong Pyo, Kuk Kang, and Dong Lee. "Preparation and characterization of quercetin-loaded silica microspheres stabilized by combined multiple emulsion and sol-gel processes." Chemical Industry and Chemical Engineering Quarterly 21, no. 1-1 (2015): 85–94. http://dx.doi.org/10.2298/ciceq131002010k.

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Despite exhibiting a wide spectrum of cosmeceutical properties, flavonoids and related compounds have some limitations related to their stability and solubility in distilledwater. In this project, we prepared silica microspheres using a novel method that uses polyol-in-oil-in-water (P/O/W) emulsion and sol-gel methods as techniques for stabilizing quercetin. A stable microsphere suspension was successfully preparedusing a mixed solvent system comprising a polyol-phase medium for performing the sol-gel processing of tetraethyl orthosilicate (TEOS) as an inorganic precursor with outer water phase. The morphology of the microsphere was evaluated using a scanning electron microscope (SEM), which showed a characteristic spherical particle shape with a smooth surface. Furthermore, SEM/EDSanalysis of a representative microsphere demonstrated that the inner structure of the silica microspheres was filled with quercetin. The mean diameter of the microsphere was in the range 20.6-35.0 ?m, and the encapsulation efficiency ranged from 17.8% to 27.5%. The free and encapsulated quercetin samples were incubated in separateaqueous solutions at 25 and 42?C for 28 days. The residualcontent of the quercetin encapsulated by silica microspheres was 82% at 42?C. In contrast, that of the free quercetin stored at 42?C decreased to ~24%.
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li, Zuo Sheng, Yan Zhang, Yu Jian Liu, Jun Fang, and Wei Ling Luan. "Preparation and Characterization of W@SiO2 Shielding Composite Microsphere." Advanced Materials Research 1120-1121 (July 2015): 260–63. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.260.

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W@SiO2 shielding composite microspheres were prepared by Sol-gel method for the first time. The component and morphology were investigated by Fourier transform infrared (FT-IR) spectra, Transmission electron microscopy (TEM) and Energy dispersive X-ray spectroscopy (EDX). The results reveal that polyvinylpyrrolidone (PVP) was introduced to the surface of tungsten nanoparticle successfully, and tungsten nanoparticle had been coated with silica. The appropriate hydrolysis reaction time is 3h, core-shell structure W@SiO2 shielding composite microsphere can be synthesized and free silica decrease sharply. Core element and shell element of W@SiO2 shielding composite microspheres were proved to be tungsten and silica respectively.
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Fan, Huibo, Dawei Zhou, Li Fan, Yuanyan Wu, Hao Tao, and Junbin Gong. "Excitation of Multi-Beam Interference and Whispering-Gallery Mode in Silica Taper-Assisted Polymer Microspheres for Refractometric Sensing." Photonics 8, no. 4 (April 10, 2021): 117. http://dx.doi.org/10.3390/photonics8040117.

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We propose and numerically analyze a fiber-optic sensor based on a silica taper-assisted multiple polymer microspheres to realize high-sensitivity refractometric sensing due to the excitation of multi-beam interference and whispering-gallery modes (WGMs) in each microsphere. Up to 5 UV-cured adhesive microspheres are dripped in sequence on the 2 µm-diameter silica taper with the certain distances in between. Scattering and reflection of light in each microsphere enhance the multi-beam interference because of the emergence of high-order modes. Moreover, WGMs with certain resonant wavelengths are excited in the microspheres, further enhancing the transmission spectrum with high contrast and quality factor. Furthermore, irregular transmission spectrum corresponds to the large wavelength tuning range. Propagating light between the microspheres could be strongly affected by the environmental factor with the large transmission spectrum shift, therefore realizing the refractometric sensing with high sensitivity of 846 nm/RIU based on the taper-assisted 2-spheres sensor. Furthermore, another two microspheres are placed on both sides of 2-spheres sensor to form 4-spheres-loop sensor, re-collecting those large-angle scattering light with the enhancement of multi-beam interference and WGMs. Therefore, the sensitivity of 4-shperes-loop sensor is further improved to the maximum of 1296.3 nm/RIU.
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Liu, Lin, Wen Juan Guo, Zhao Dai, Ming Jing Li, and Jun Fu Wei. "Preparation of Marcoporous and Hollow Silica Microspheres with Raspberry-Like Organic Composite Particles as Templates." Applied Mechanics and Materials 372 (August 2013): 13–16. http://dx.doi.org/10.4028/www.scientific.net/amm.372.13.

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Marcoporous silica hollow microspheres were prepared by poly (acrylic acid)@poly (ethyleneglycol dimethacrylate-co-4-vinylpyridine) (PAA@P(EGDMA-co-VPy)) composite particles with raspberry-like structure as the template. P(EGDMA-co-VPy) and PAA microspheres were prepared by distillation precipitation polymerization respectively. The raspberry-like organic composite polymer particles were obtained through the self-assembly of PAA microspheres on P(EGDMA-co-VPy) microspheres. Then, Silica layer was coated on the composite particles with Stöber method in an alkaline environment. The marcoporous silica hollow microspheres were received after the calcination to remove the organic template. The diameter of the marcoporous silica hollow microspheres, hollow inner core and the pore size of silica layer was about 2.0 μm, 1.5 μm and 20-130 nm, respectively.
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Lin, Yi, Jinjia Xu, Bhosale Sanjana Sudhakar, Junjie Gu, and Ruoyu Hong. "Preparation of spherical aminopropyl-functionalized MCM-41 and its application in removal of Pb(II) ion from aqueous solution." Nanotechnology Reviews 8, no. 1 (November 26, 2019): 275–84. http://dx.doi.org/10.1515/ntrev-2019-0026.

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Abstract Mesoporous silica microspheres were prepared by the polymerization-induced colloid aggregation (PICA) and pseudomorphic synthesis methods. The prepared microspheres have high specific surface area and MCM-41 type structure. In the PICA process, acidic silica sol was utilized as silica source and the effect of molar ration (formaldehyde/urea) was investigated. Moreover, the influences of reaction time and temperature were also studied. The specific surface area of porous and mesoporous silica microspheres were 186.4 m2/g and 900.4 m2/g, respectively. The materials were characterized by SAXS, FTIR, SEM, TEM and nitrogen sorption measurements. The prepared silica microspheres were functionalized by (3-Aminopropyl)triethoxysilane and then used to remove the lead from aqueous solution. The result indicates that the grafted silica microspheres have rapid adsorption capacity and good reproducibility. The adsorption data was fitted well with the Langmuir isotherm model, and the maximum adsorption capacities for MCM-41 silica microspheres were 102.7 mg/g.
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Taksavasu, Tadsuda, Thomas Monecke, and T. Reynolds. "Textural Characteristics of Noncrystalline Silica in Sinters and Quartz Veins: Implications for the Formation of Bonanza Veins in Low-Sulfidation Epithermal Deposits." Minerals 8, no. 8 (August 2, 2018): 331. http://dx.doi.org/10.3390/min8080331.

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Silica sinters forming at the Wairakei geothermal power plant in New Zealand are composed of noncrystalline opal-A that deposited rapidly from cooling geothermal liquids flashed to atmosphere. The sinter is laminated with alternating layers of variably compacted silicified filamentous microbes encased by chains of fused silica microspheres. Microscopic inspection of bonanza quartz vein samples from the Buckskin National low-sulfidation epithermal precious metal deposit in Nevada showed that colloform bands in these veins exhibit relic microsphere textures similar to those observed in the silica sinters from the Wairakei power plant. The textural similarity suggests that the colloform bands were originally composed of noncrystalline opal-A that subsequently recrystallized to quartz. The colloform bands contain dendrites of electrum and naumannite that must have grown in a yielding matrix of silica microspheres deposited at the same time as the ore minerals, implying that the noncrystalline silica exhibited a gel-like behavior. Quartz bands having other textural characteristics in the crustiform veins lack ore minerals. This suggests that ore deposition and the formation of the colloform bands originally composed of compacted microspheres of noncrystalline silica are genetically linked and that ore deposition within the bonanza veins was only episodic. Supersaturation of silica and precious metals leading to the formation of the colloform bands may have occurred in response to transient flashing of the hydrothermal liquids. Flashing of geothermal liquids may thus represent a key mechanism in the formation of bonanza precious metal grades in low-sulfidation epithermal deposits.
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Cheng, Xiao Su, Ling Ke Zeng, Xiu Yan Li, Wen Yan Sheng, An Ze Shui, Ze Hao Liu, Ying Yuan Zhang, Yue Wang, and Yong Zhao Wang. "Preparation and Microstructure of Bauxite Ceramic Microsphere." Key Engineering Materials 336-338 (April 2007): 1124–26. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.1124.

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In this paper, microspheres were prepared by using Chinese bauxite as raw materials through centrifugal spray drying method. The microstructure and composition of ceramic microsphere were investigated by X-ray diffraction, scanning electron microscope and X-ray energy spectrum. The particle size was 10~100#m. The XRD analysis reveals that the main crystalline phase of the ceramic microsphere were α-Al2O3 and mullite (3Al2O3•2SiO2). The Al2O3 content (chemical composition) of the microspheres was little more than 70%, and the molar ratio of Al2O3/SiO2 was near to the molar ratio of alumina and silica of mullite.
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Dissertations / Theses on the topic "Silica microspheres"

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Kandas, Ishac Lamei Nagiub. "Silica Microspheres Functionalized with Self-assembled Nanomaterials." Diss., Virginia Tech, 2013. http://hdl.handle.net/10919/19232.

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A major limitation of silica-based high-Q microcavities is the lack of functionalities such as gain, plasmonic resonance, and second-order nonlinearity. Silica possesses third order nonlinearity but cannot produce second order nonlinearity, plasmonic resonances, or fluorescence emission. The key to overcome this deficiency is to develop versatile methods that can functionalize the surface of a silica microsphere with appropriate nanomaterials. The goal of this thesis is to present and characterize an electrostatic self-assembly based approach that can incorporate a large number of functional materials onto the surface of a silica resonator with nanoscale control. We consider several types of functional materials: polar ionic self-assembled multilayer (ISAM) films that possess second order nonlinearities, Au nanoparticles (NPs) that support plasmonic resonances, and fluorescent materials such as CdSe/ZnS core/shell QDs.
A major part of this thesis is to investigate the relationship between cavity Q factors and the amount of nanomaterials deposited onto the silica microspheres. In particular, we fabricate multiple functional microspheres with different ISAM film thickness and Au NPs density. We find that the Q factors of these microspheres are mainly limited by optical absorption in the case of the ISAM film, and a combination of optical absorption and scattering in the case of the Au NPs. By controlling the number of polymer layers or the NPs density, we can adjust the Q factors of these functional microspheres in the range of 106 to 107. An agreement between theoretical prediction and experimental data was obtained. The results may also be generalized to other functional materials including macromolecules, dyes, and non-spherical plasmonic NPs.
We also study the adsorption of Au NPs onto spherical silica surface from quiescent particle suspensions. The surfaces consist of microspheres fabricated from optical fibers and were coated with a polycation, enabling irreversible nanosphere adsorption. Our results fit well with theory, which predicts that particle adsorption rates depend strongly on surface geometry. This is particularly important for plasmonic sensors and other devices fabricated by depositing NPs from suspensions onto surfaces with non-trivial geometries.
We use two additional examples to illustrate the potential applications of this approach. First, we explored the possibility of achieving quasi-phase-matching (QPM) in a silica fiber taper coated with nonlinear polymers. Next, we carry out a preliminary investigation of lasing in a silica fiber coated with CdSe/ZnS core/shell quantum dots (QDs).

Ph. D.
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Hofmann, Matthias Colin. "Second Order Nonlinear Silica-Based Fibers and Microspheres." Thesis, Virginia Tech, 2009. http://hdl.handle.net/10919/76786.

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After decades of development, optical fiber technology has reached a high degree of sophistication and maturity, and currently serves as the backbone of today''s internet. Despite its technical versatility and capability, current silica fiber technology still has a significant flaw: since silica fibers only possess very weak second order nonlinearity, it has been impossible to develop a large number of important nonlinear optical devices and instruments, such as optical parametric amplifiers (OPA) and optical parametric oscillators (OPO). In this thesis,we show how to overcome this intrinsic limitation, and introduce second order nonlinearity into silica fiber devices.
Master of Science
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Ahmed, Adham Saleh. "Morphology control on porous monoliths and silica microspheres and applications in chromatography." Thesis, University of Liverpool, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.569199.

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Silica-based stationary phases have been under investigation since they were first produced, and studies still continue to try to improve their morphology and porosity. A handful of reliable and straightforward synthetic procedures are used routinely for their manufacture. The most widely applied procedures are variations of the modified Stober synthesis route that allow the manufacture of relatively monodisperse particles in the nanometer range, or the sol-gel route that produces larger porous microstructures. However, the controlled manufacture of silica stationary phase with the desired physical properties is still a challenge, and most of their preparation involves multi-step preparation, adding cost and time. This dissertation outlines work that introduces a set of new protocols that were developed for the preparation of silica with controlled morphology and porosity. Herein, silica microspheres with tuneable pore size and particle size distribution were synthesised using a modified Stober method. Hydrophilic polymers were introduced into the reaction system, which acted as stabilising agent. Further altering the reaction parameters resulted in the formation of silica microspheres with controlled surface morphology, beads-on-bead silica particles. The preparation conditions were extensively studied in order to understand the reason for such phenomena. The beads-on-beads particles exhibit chromatographic potential, especially for proteins separation. Moreover, porous silica microspheres were further used for the preparation of hierarchically porous silica monoliths by a controlled freezing approach. The macropore morphologies could be tuned with the addition of surfactants in the silica colloidal suspensions during the freezing process. The engineering of porosity and improvement on mechanical stability of the silica materials were achieved through a further soaking and sol-gel process. It was also possible to enhance the mechanical stability through thermal treatment of the materials. Directional freezing approach was also evaluated to direct the assembly of silica nanoparticles. The presence of water-soluble polymers resulted in better aligned features and acted as a gelling agent in the case of charged polymer. The monolith was successfully prepared inside a fused-silica capillary column and was investigated for chromatographic applications. Preformed emulsion-templated porous polyacrylamide beads and monolith were used as a scaffold for controlled growth of silica spheres on macroporous surface. A hierarchical hybrid structure was formed. The polymer scaffold could be removed to form porous silica spheres and macroporous structures. Further investigation was considered to control the porosity and the size of the forming microspheres. This study was further extended into the preparation of fluorescent silica spheres and composite materials. Furthermore, a simple and generic method was also developed for the preparation of gradient emulsion-templated structures. The gradient could be achieved with the aid of centrifugation mechanism. This method enabled the formation of dual gradient mesoporous and macroporous composites.
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Kong, Yupeng. "Modulation of like-charge attraction by lipid and protein functionalized silica microparticles." Thesis, University of Oregon, 2010. http://hdl.handle.net/1794/11436.

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xii, 138 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
Controlling colloidal interactions continues to receive a great deal of attention due both to basic scientific interests as well as industrial applications. However, many aspects of interactions between microparticles remain poorly understood, including the attraction observed between particles with the same kind of charge (like-charge attraction). This situation hinders progress in the generation of colloidal self-assembled structures. This thesis focuses on measurements of pair interactions of functionalized silica microspheres and the resulting insights into colloidal interactions. Silica microparticles were functionalized in two ways. For one method, each particle was coated with a lipid inlayer membrane. The charge density of the particle surface can thereby be easily tuned by controlling the type or amount of charged lipids. For the other method, the cholera toxin subunit B protein (CTB) was bound to lipid-functionalized microparticles. To measure pair interactions, we invented a line optical trap that enables nearly free one-dimensional Brownian motion of particles. Pair interaction energies of functionalized particles above the bottom of the experimental chamber can be extracted via a Boltzmann relationship. Both lipid-only and lipid-plus-protein functionalized microparticles show tunable, attractive pair interactions. For lipid-only coatings, the attraction becomes stronger by increasing the fraction of positively charged lipids. There is a linear relationship between pair potential and molar percentage of positively charged lipids. For lipid-plus-protein coatings, attractive potentials were weakened monotonically by binding more CTB. Decompositions of potential curves allow identification of directly charge-dependent and charge-independent contributions to colloidal like-charge attraction. Analysis shows that the correlations between attraction strength and range are opposite in these two sets of particles. Moreover, the correlations between particle-wall separation and attraction strength in lipid-only and lipid-plus-protein functionalized particles are also opposite. These comparisons show that like-charge attraction may result from more than one mechanism. Finally, we measured pair potential energies of lipid functionalized silica particles above a lipid functionalized glass chamber bottom, which exhibit a quadratic relationship between the attraction strength and the fraction of positively charged lipids. Compared with the situation of particle functionalization only, this relation indicates that confinement-induced like-charge attraction can be modulated by altering electrostatic properties of the confining wall.
Committee in charge: Dr. Stephen D. Kevan, Chair; Dr. Raghuveer Parthasarathy, Advisor; Dr. Hailin Wang; Dr. Miriam Deutsch; Dr. Marina G. Guenza
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Park, Young-Shin 1972. "Radiation pressure cooling of a silica optomechanical resonator." Thesis, University of Oregon, 2009. http://hdl.handle.net/1794/10559.

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xi, 125 p. : ill. (some col.) A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number.
This dissertation presents experimental and theoretical studies of radiation pressure cooling in silica optomechanical microresonators where whispering gallery modes (WGMs) are coupled to thermal mechanical vibrations. In an optomechanical system, circulating optical fields couple to mechanical vibrations via radiation pressure, inducing Stokes and anti-Stokes scattering of photons. In analogy to laser cooling of trapped ions, the mechanical motion can in principle be cooled to its ground state via the anti-Stokes process in the resolved-sideband limit, in which the cavity photon lifetime far exceeds the mechanical oscillation period. Our optomechanical system is a slightly deformed silica microsphere (with a diameter 25-30 μm ), featuring extremely high Q -factors for both optical ( Q o ∼ 10 8 ) and mechanical ( Q m ∼ 10 4 ) systems. Exploiting the unique property of directional evanescent escape in the deformed resonator, we have developed a free-space configuration for the excitation of WGMs and for the interferometric detection of mechanical displacement, for which the part of input laser that is not coupled into the microsphere serves as a local oscillator. Measurement sensitivity better than 5 × 10 -18 m /[Special characters omitted.] has been achieved. The three optically active mechanical modes observed in the displacement power spectrum are well described by finite element analysis. Both radiation pressure cooling and parametric instabilities have been observed in our experiments. The dependence of the mechanical resonator frequency and linewidth on the detuning as well as the intensity of the input laser show excellent agreement with theoretical calculations with no adjustable parameters. The free-space excitation technique has enabled us to combine resolved sideband cooling with cryogenic cooling. At a cryogenic temperature of 1.4 K, the sideband cooling leads to an effective temperature as low as 210 m K for a 110 MHz mechanical oscillator, corresponding to an average phonon occupation of 37, which is one of the three lowest phonon occupations achieved thus far for optomechanical systems. The cooling process is limited by ultrasonic attenuation in fused silica, which should diminish when bath temperature is further lowered, with a 3 He cryostat, to a few hundred millikelvin. Our experimental studies thus indicate that we are tantalizingly close to realizing the ground-state cooling for the exploration of quantum effects in an otherwise macroscopic mechanical system.
Committee in charge: Michael Raymer, Chairperson, Physics; Jens Noeckel, Member, Physics; Hailin Wang, Member, Physics; Paul Csonka, Member, Physics; Jeffrey Cina, Outside Member, Chemistry
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Knappett, Peter. "Evaluating the Effects of Grain Size and Divalent Cation Concentration on the Attenuation of Viruses and Microspheres through Crushed Silica Sand." Thesis, University of Waterloo, 2006. http://hdl.handle.net/10012/906.

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Over the last decade in North America, an increasing number of microbiological drinking water regulations have been used to manage groundwater resources that are potentially influenced by surface water. Regulations such as the Ontario Ministry of Environment Regulation 505, which requires at least a 60 day groundwater travel time between surface waters and drinking water wells, have been created with limited understanding of subsurface pathogen transport processes. Groundwater Under Direct Influence studies (GUDI or GWUDI in USA) are conducted to assess the need to treat well water at an extraction point. Currently, there is a lack of knowledge regarding factors that affect the transport of pathogens through porous media at the surface water-groundwater interface. Such information is required to supply sufficient quantities of drinking water in a cost effective and safe manner.

Factors that affect pathogen transport through porous media include: properties of the pathogen (i. e. surface charge, size, and morphology), properties of the granular media (i. e. mineralogy, size, texture, angularity) and properties of the water (i. e. pH, ionic strength and content, and natural organic matter). This study examines the effects of ionic strength, grain size and influent virus concentrations on pathogen transport in porous media. Fourteen column tests were conducted using the bacteriophage MS2 and 1. 5 µm microspheres; two commonly used non-pathogenic surrogates representative of human viruses and bacteria, respectively. Two size distributions of crushed silica sand, with median grain diameters of 0. 7 and 0. 34 mm, and two ionic strengths of 8 and 95 mmol/L were used. A 22 partial factorial design was used with a minimum of two replicates of each combination of the parameters.

The results show that complete breakthrough of both viruses and microspheres occurred in medium sand at low ionic strength. It was found that increasing ionic strength by Ca2+ addition precluded breakthrough of MS2 in both the medium and fine sands. This represents a greater than 8 log reduction in peak effluent concentration and essentially complete attenuation.

In fine sand, with low ionic strength water, a 5 log reduction in peak MS2 concentrations was observed. In the same sand at high ionic strength, no MS2 broke through the column, corresponding to a greater than 8 log removal. Since complete attenuation occurred in both grain sizes at high ionic strength, the effect of higher ionic strength in the fine sand was indistinguishable from the effect observed from raising the ionic strength in the medium sand.

In contrast to the viruses, microsphere transport was essentially unaffected by increasing ionic strength under the conditions investigated. A 1 log reduction in peak concentration was observed in the high ionic strength water in the medium sand. In spite of this, grain size had a profound effect on the attenuation of microspheres. There was no evidence of microsphere breakthrough in any of the fine sand columns at the low or high ionic strengths, yielding a greater than 5 log reduction in microsphere concentration associated with grain size alone. The effect of varying virus concentration was also investigated. It was found that varying the concentration of viruses between 105 and 107 pfu/ml had no discernable effect on their observed transport characteristics; normalised peak breakthrough concentration, percent attenuation and retardation relative to a bromide tracer.

Based on the results from this Thesis, in a riverbank filtration environment, there is reason to expect that, at comparable water qualities and in similar porous media, multiple logarithmic reductions of viruses and bacteria would occur over the much longer (than column length) flowpaths associated with RBF. There is also reason to expect this attenuation capability to vary based on riverbank grain size and water chemistry.
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Arraud, Nicolas. "Etude cinétique de la liaison élémentaire entre Annexine-A5 et membranes et mise au point d’un test de quantification des microparticules plasmatiques pro-coagulantes, par cytométrie en flux." Thesis, Bordeaux 1, 2011. http://www.theses.fr/2011BOR14459/document.

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L’Annexine A5 (AnxA5) est une protéine soluble se liant aux membranes contenant de la phosphatidylsérine (PS) en présence de calcium (Ca2+). Le rôle central joué par l’AnxA5 dans les processus de réparation membranaire a été récemment mis en évidence. L’AnxA5 possède une très forte affinité pour les membranes biologiques contenant de la PS, cependant son mode de liaison aux membranes n’est pas encore élucidé.La première partie de mon travail de thèse a concerné le développement d’une approche originale d’étude de la liaison de l’AnxA5 à des microsphères de silice fonctionnalisées par une bicouche lipidique (µPSiO2@SLB pour supported lipid bilayer), par cytométrie en flux (FCM). Cette approche m’a permis d’étudier la liaison à l’équilibre et en cinétique à très faible concentration en AnxA5, de l’ordre du picomolaire. Cette approche représente une des méthodes les plus sensibles d’étude de liaison à l’équilibre et la première permettant d’accéder aux constantes cinétiques d’interaction pour l’AnxA5. Cette étude m’a également permis de mettre au point une stratégie de dosage indirect de liposomes contenant de la PS avec une sensibilité de l’ordre du nanogramme de lipides par millilitre.La seconde partie de ma thèse a concerné l’étude de microparticules (MP), fragments de membranes cellulaires présents dans les fluides biologiques. Dans le plasma sanguin la majorité des MP sont d’origine plaquettaire et exposent de la PS. Il existe une corrélation entre la concentration en MP plasmatiques exposant de la PS et le développement de pathologies thrombotiques. La FCM est la méthode de référence dans l’étude des MP cependant leur détection est rendue difficile par leur petite taille. J’ai appliqué aux MP plasmatiques le test de dosage développé pour les liposomes. Les résultats obtenus sont prometteurs et permettent d’envisager le développement d’un test de dosage de l’ensemble des MP exposant de la PS
Annexin-A5 (AnxA5) is a soluble membrane binding protein that binds to phosphatidylserine (PS) containing membranes in a calcium dependent manner and plays a central role in cell membrane repair processes. AnxA5 has a remarkably high affinity for PS containing membranes, but its binding mechanism remains unclear.The first part of my PhD work was to develop a new method for studying AnxA5 binding using supported lipid bilayer functionalized silica microspheres (µPSiO2@SLB) and Flow Cytometry (FCM). This approach allowed me to describe in details both equilibrium and kinetics of AnxA5 binding at picomolar concentrations in AnxA5. This study is one of the most sensitive for equilibrium binding studies and the first allowing to measure binding kinetics constants for AnxA5. This study also led to the development of a new strategy for determination of liposome concentration with sensitivity in the range of one nanogram of lipid per milliliter. The second part of my work focused on microparticles (MP) that are cell membrane fragments found in biological fluids. In plasma, the vast majority of MP originates from platelets and expresses PS at their surface. There is a correlation between MP concentration in plasma and thrombotic risk. FCM is the “golden standard” of hæmatologic analysis but the majority of MPs are too small to be detected. I have applied the test developed with liposomes for the quantification of MP. The results are promising and allow foreseeing the development of a test able to give the absolute quantity of PS exposing MPs in plasma samples
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Pazos, Cecilia. "Préparation et propriétés de microsphères de silice monodispersées /." [S.l.] : [s.n.], 1991. http://library.epfl.ch/theses/?nr=961.

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TREUSSART, FRANCOIS-MICHEL. "Etude experimentale de l'effet laser dans des microspheres de silice dopees avec des ions neodyme." Paris 6, 1997. http://www.theses.fr/1997PA066733.

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Ce travail de these porte sur la mise en evidence de l'effet laser dans des microresonateurs optiques de tres haute surtension, bases sur les modes de galerie de microspheres de silice d'un diametre de 50 a 100 m. Ces modes resonnants correspondent a une propagation guidee par reflexion totale interne. La lumiere est ainsi confinee dans un anneau equatorial dont les dimensions transversales sont de l'ordre de la longueur d'onde, ce qui donne lieu a une forte exaltation du champ lumineux. Les pertes de ces modes guides sont extremement faibles. Ils offrent donc la combinaison remarquable d'une tres forte localisation du champ dans un tout petit volume et de tres longs temps de vie pour les photons. Ces proprietes en font des resonateurs de choix tant pour obtenir des effets d'optique non-lineaire a tres bas seuil que pour des experiences d'electrodynamique quantique en cavite. Ce memoire presente d'abord les proprietes de ces resonances et leur observation experimentale par spectroscopie laser. Le dedoublement de ces resonances par retrodiffusion interne est ensuite decrit et interprete par un modele d'oscillateurs couples, en bon accord avec les experiences. La realisation d'un microlaser avec des microbilles dopees au neodyme est ensuite presentee. Les tres bas seuils observes (200 nw) correspondent bien aux predictions theoriques obtenues par un modele semi-classique approprie. Pour renforcer les effets de cavite, ces experiences ont ete poursuivies en immergeant les microspheres dans l'helium superfluide. Le montage cryogenique mis au point nous permet de conserver des surtensions a 2 k de 10#9 et l'emission laser a pu etre observee, ouvrant la voie a la recherche d'un fonctionnement laser avec seulement quelques ions couples a quelques photons.
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COLLOT, LAURENT. "Etude theorique et experimentale des resonances de galerie de microspheres de silice : pieges a photons pour des experiences d'electrodynamique en cavite." Paris 6, 1994. http://www.theses.fr/1994PA066532.

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Ce travail de these porte sur l'etude des resonances de galerie de tres haute surtension observees sur des microspheres de silice d'un diametre voisin de 100m. Ces resonances correspondent a des modes de propagation du champ le long d'un anneau equatorial dont les dimensions transversales sont de l'ordre de la longueur d'onde. Les pertes de ces modes guides sont extremement faibles. Ils offrent donc une combinaison remarquable d'une tres forte localisation du champ dans un tout petit volume et de tres longs temps de vie pour les photons. Ces proprietes en font des resonateurs de choix tant pour de nombreuses applications pratiques que pour des experiences d'electrodynamiques quantique en cavite. Le memoire de these presente les proprietes de ces resonances, decrit leur observation experimentale par spectroscopie laser et analyse quelques perspectives ouvertes par ces etudes en physique appliquee et fondamentale. Les possibilites d'utiliser ces modes de galerie pour asservir en phase un laser a diode ou pour fabriquer des lasers microscopiques sont envisagees. Une experience de deflexion d'atomes froids dans l'onde evanescente associee a un mode de galerie est egalement etudiee. Une telle experience devrait permettre de mettre en evidence la nature discrete de l'intensite d'un champ lumineux constitue de quelques photons et realiser une mesure dispersive extremement sensible de tous petits champs optiques
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Books on the topic "Silica microspheres"

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Han, Jeannie. Polymer encapsulation of composite titanyl sulfate coated silica microspheres. 2001.

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Book chapters on the topic "Silica microspheres"

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Hay, Jennifer. "Compression Testing of Silica Microspheres with Synchronized SEM Video." In Conference Proceedings of the Society for Experimental Mechanics Series, 53–57. Cham: Springer International Publishing, 2016. http://dx.doi.org/10.1007/978-3-319-42028-8_7.

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Cacaina, D., Reeta Viitala, Mika Jokinen, Heimo O. Ylänen, Mikko Hupa, and S. Simon. "In Vitro Behavior of Yttrium Silica Sol-Gel Microspheres." In Bioceramics 17, 411–14. Stafa: Trans Tech Publications Ltd., 2005. http://dx.doi.org/10.4028/0-87849-961-x.411.

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Louh, Rong Fuh, and Eric Huang. "Electrophoretic Self-Assembly of Sol-Gel Derived Silica Microspheres." In Solid State Phenomena, 599–602. Stafa: Trans Tech Publications Ltd., 2007. http://dx.doi.org/10.4028/3-908451-31-0.599.

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Kaiser, Ch, M. Hanson, H. Giesche, J. Kinkel, and K. K. Unger. "Nonporous Silica Microspheres in the Micron and Submicron Size Range." In Fine Particles Science and Technology, 71–84. Dordrecht: Springer Netherlands, 1996. http://dx.doi.org/10.1007/978-94-009-0259-6_6.

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Bei, I., A. Tolstov, and A. Ishchenko. "Synthesis of Hollow Silica Microspheres with High-Developed Surface Area." In NATO Science for Peace and Security Series A: Chemistry and Biology, 215–19. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-94-007-2488-4_22.

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Devender and Ajay Dangi. "Titanium-Dioxide-Coated Silica Microspheres for High-Efficiency Dye-Sensitized Solar Cell." In Ceramic Transactions Series, 27–32. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2011. http://dx.doi.org/10.1002/9781118144527.ch3.

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Zhou, Limin, Hongbin Zou, Jieyun Jin, Zhirong Liu, and Taian Luo. "Preparation of phosphonic acid-functionalized silica magnetic microspheres for uranium(VI) adsorption from aqueous solutions." In Advances in Energy and Environment Research, 103–8. Taylor & Francis Group, 6000 Broken Sound Parkway NW, Suite 300, Boca Raton, FL 33487-2742: CRC Press, 2017. http://dx.doi.org/10.1201/9781315212876-22.

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Barnes, Jack A., Gianluca Gagliardi, and Hans-Peter Loock. "Cavity-Enhanced Spectroscopy on Silica Microsphere Resonators." In Springer Series in Optical Sciences, 351–83. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-40003-2_10.

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Kobayashi, Isao, Mitsutoshi Nakajima, Yuji Kikuchi, Kyoseok Chun, and Hiroyuki Fujita. "Micromachined Straight-Through Silicon MicroChannel Array for Monodispersed Microspheres." In Microreaction Technology, 41–48. Berlin, Heidelberg: Springer Berlin Heidelberg, 2001. http://dx.doi.org/10.1007/978-3-642-56763-6_4.

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Zeng, Yan. "Structuring of Nanoparticles Confined Between a Silica Microsphere and an Air Bubble." In Colloidal Dispersions Under Slit-Pore Confinement, 83–97. Berlin, Heidelberg: Springer Berlin Heidelberg, 2012. http://dx.doi.org/10.1007/978-3-642-34991-1_6.

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Conference papers on the topic "Silica microspheres"

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Albers, Dylan, and Mileva Radonjic. "Prevention of Alkali-Silica Reaction (ASR) in Light-Weight Wellbore Cement Comprising Silicate-Based Microspheres." In ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/omae2017-62015.

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Drilling through low pressure formations, either offshore or through depleted formations, requires the use of low density fluids to prevent lost circulation and as well as to properly place cement during cementing applications. Achieving these densities in cements can be done through foaming the cement, increasing water content, or through the addition of silica based microspheres. Each of these methods have individual limitations, and in the case of silica based microspheres, their specific fallback is a chemical instability with the microsphere itself reacting with the cement pore fluid. This chemical instability creates a hydrophilic gel that is expansive and creates fractures in the cement as it expands, which is more formally referred to as alkali-silica reactivity (ASR). Prevention of ASR involves the application of additives to the cement that acts as a sink for the alkalinity in which prevents the expansion of ASR. A specific application that this paper investigates for this prevention is the use of Lithium nitrate. This study looks at the effects of a high alkalinity environment onto the microspheres by visualizing the reactions that are occurring using Scanning Electron Microscopy (SEM), and confirming the presence of ASR when silica based microspheres encounter a high pH environment. Then cement samples were created to compare the effects lithium nitrate has on cements created with silica based microspheres. SEM and micro indentation was conducted on these samples, which showed that lithium nitrate prevents reactions, but after 28-day hydration a loss of mechanical properties is present.
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Ferreira, Marta S., José L. Santos, and Orlando Frazão. "New silica microspheres array sensor." In OFS2014 23rd International Conference on Optical Fiber Sensors, edited by José M. López-Higuera, Julian D. C. Jones, Manuel López-Amo, and José L. Santos. SPIE, 2014. http://dx.doi.org/10.1117/12.2059619.

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Alombert-Goget, Guillaume, Cristina Armellini, Simone Berneschi, Alessandro Chiasera, Franco Cosi, Gualtiero Nunzi Conti, Patrice Feron, et al. "Glass-ceramics coating of silica microspheres." In 2009 3rd ICTON Mediterranean Winter Conference (ICTON-MW 2009). IEEE, 2009. http://dx.doi.org/10.1109/ictonmw.2009.5385639.

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Jiang, Xuefeng, Mark Kuzyk, Thein Oo, and Hailin Wang. "Chip-based silica microspheres for cavity optomechanics." In CLEO: Science and Innovations. Washington, D.C.: OSA, 2015. http://dx.doi.org/10.1364/cleo_si.2015.sth4i.1.

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Kane, D. M., R. J. Chater, and D. S. McPhail. "Focussed ion beam milling of silica microspheres." In Devices (COMMAD). IEEE, 2010. http://dx.doi.org/10.1109/commad.2010.5699684.

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Lv, Hao, and Aimei Liu. "Fabrication and Optical Characterization of Silica Microspheres." In 2015 International Conference on Education, Management, Information and Medicine. Paris, France: Atlantis Press, 2015. http://dx.doi.org/10.2991/emim-15.2015.69.

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Ristic, Davor, Alessandro Chiasera, Enrico Moser, Patrice Feron, Gilles Cibiel, Mile Ivanda, Giancarlo C. Righini, and Maurizio Ferrari. "Whispering gallery modes in coated silica microspheres." In SPIE Photonics Europe. SPIE, 2012. http://dx.doi.org/10.1117/12.921620.

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Gomes, André D., Beatriz Silveira, Fatemeh Karami, Mohammad I. Zibaii, Hamid Latifi, Jan Dellith, Martin Becker, Manfred Rothhardt, Hartmut Bartelt, and Orlando Frazão. "Multi-path interferometer structures with cleaved silica microspheres." In Interferometry XIX, edited by Michael B. North Morris, Katherine Creath, Jan Burke, and Angela D. Davies. SPIE, 2018. http://dx.doi.org/10.1117/12.2319082.

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Webb, Karen E., Miro Erkintalo, Stéphane Coen, and Stuart G. Murdoch. "Cavity soliton frequency comb generation in silica microspheres." In Australian Conference on Optical Fibre Technology. Washington, D.C.: OSA, 2016. http://dx.doi.org/10.1364/acoft.2016.jw6a.4.

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Micko, Michaela K., Matthias Brendle, and Judith M. Dawes. "Direct opal fabrication from silver-coated silica microspheres." In 12th European Quantum Electronics Conference CLEO EUROPE/EQEC. IEEE, 2011. http://dx.doi.org/10.1109/cleoe.2011.5942855.

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Reports on the topic "Silica microspheres"

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Pascoguin, B. N., R. P. Lu, J. M. Kvavle, and A. D. Ramirez. Road to Silicon Microsphere Fabrication and Mode Coupling. Fort Belvoir, VA: Defense Technical Information Center, July 2014. http://dx.doi.org/10.21236/ada607718.

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Peacock, H. B. A feasibility study to determine blending characteristics and extrudability of aluminum and silicon carbide coated microspheres. Office of Scientific and Technical Information (OSTI), January 1988. http://dx.doi.org/10.2172/6755791.

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