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Sample records for nano silica morphology

  1. Action of colloidal silica films on different nano-composites

    NASA Astrophysics Data System (ADS)

    Abdalla, S.; Al-Marzouki, F.; Obaid, A.; Gamal, S.

    Nano-composite films have been the subject of extensive work to develop the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nano-particles size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that form an insulating film between conductive electrodes of a capacitor. This in turn affects the energy storage performance of the capacitor. In the present work, we have studied the dielectric properties of 4 high pure amorphous polymer films: polymethylmethacrylate (PMMA), polystyrene, polyimide and poly-4-vinylpyridine. Comparison between the dielectric properties of these polymers has revealed that the higher break down performance is a character of polyimide PI and PMMA. Also, our experimental data shows that adding colloidal silica to PMMA and PI leads to a net decrease in the dielectric properties compared to the pure polymer.

  2. Acrylic coatings exhibiting improved hardness, solvent resistance and glossiness by using silica nano-composites

    NASA Astrophysics Data System (ADS)

    Dashtizadeh, Ahmad; Abdouss, Majid; Mahdavi, Hossein; Khorassani, Manuchehr

    2011-01-01

    To prepare nano-composite emulsion acrylic resins with improved surface hardness and solvent resistance, nano-silica particles were treated with surfactants. The monomers of methyl methacrylate/butylacrylate were co-polymerized on the surface of dispersed silica particles. Several emulsions with different silica contents and copolymer mole fractions were prepared. Finally the emulsions were modified to water-based acrylic coatings and improved properties such as surface hardness, solvent resistance and glossiness were determined. The study of coatings was directed to find the improved resin by optimum surface properties. Size distribution and morphology of latexes were characterized by Fourier transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy and scanning electron microscopy. The glass transition temperature of nano-composites was measured and discussed its relation with silica contents, monomer mole fractions and improved properties of coatings. The optimum pendulum hardness of coatings was on 0.46 methyl methacrylate mole fraction and 120 g silica content. An increase in pendulum hardness of nano-composites with the addition of modified silica was observed. DLS and TEM studies indicate that silica particles were dispersed homogenously through the polymer matrix.

  3. Performance of concrete incorporating colloidal nano-silica

    NASA Astrophysics Data System (ADS)

    Zeidan, Mohamed Sabry

    Nanotechnology, as one of the most modern fields of science, has great market potential and economic impact. The need for research in the field of nanotechnology is continuously on the rise. During the last few decades, nanotechnology was developing rapidly into many fields of applied sciences, engineering and industrial applications, especially through studies of physics, chemistry, medicine and fundamental material science. These new developments may be attributed to the fact that material properties and performance can be significantly improved and controlled through nano-scale processes and nano-structures. This research program aims at 1) further understanding the behavior of cementitious materials when amended on the nano-scale level and 2) exploring the effect of this enhancement on the microstructure of cement matrix. This study may be considered as an important step towards better understanding the use of nano-silica in concrete. The main goal of the study is to investigate the effect of using colloidal nano-silica on properties of concrete, including mechanical properties, durability, transport properties, and microstructure. The experimental program that was conducted included a laboratory investigation of concrete mixtures in which nano-silica was added to cement or to a combination of cement and Class F fly ash. Various ratios of nano-silica were used in concrete mixtures to examine the extent and types of improvements that could be imparted to concrete. The conducted experimental program assessed these improvements in terms of reactivity, mechanical properties, and durability of the mixtures under investigation. Advanced testing techniques---including mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM)---were used to investigate the effect of nano-silica on the microstructure of the tested mixtures. In addition, the effect of nano-silica on the alkali-silica reaction (ASR) was examined using various techniques, including testing

  4. Modelling of nano-silica in cement paste

    NASA Astrophysics Data System (ADS)

    Rupasinghe, Madhuwanthi; Mendis, Priyan; Sofi, Massoud; Ngo, Tuan

    2013-08-01

    Recently published experimental evidence shows that nano-silica is a material that can be used to enhance the strength and durability characteristics of concrete. Engineered concrete at the nano-scale is achieved through the integration of nano-materials in suitable proportions and relevant mixing methods. Being a pozzolanic and reactive material along with nucleation effects and miniature particle size, nano-silica has been found to significantly improve the micro-structural characteristics of concrete making it denser and more uniform. The ongoing research work at the University of Melbourne is based on a novel modelling approach to further investigate the performance characteristics of nano-silica on cement paste at the micro-meter scale. The volumetric proportions of different phases present in concrete are computed considering hydration characteristics of cement and those of nanosilica. A Representative Volume Element (RVE) of the cement paste at micro scale is developed considering the hydrated gel as the matrix material while other phases present are integrated as randomly distributed spherical particles. Constitutive material models for these phases are assumed. The stress-strain relationship for the RVE is then generated using COMSOL Multiphysics software. The approach proposed in this paper is an initiation towards developing an acute and compressive model to predict the performance characteristics of nano-engineered concrete.

  5. Engineering the synthesis of silica-gold nano-urchin particles using continuous synthesis

    NASA Astrophysics Data System (ADS)

    Sebastian, Víctor; Lee, Seung-Kon; Jensen, Klavs F.

    2014-10-01

    Compared to freestanding nanoparticles, supported nanostructures typically show better mechanical stability as well as ease of handling. Unique shapes such as core-shells, raspberries and crescents have been developed on supported materials to gain improved chemical and optical properties along with versatility and tunability. We report the formation of hyper-branched gold structures on silica particles, silica-gold nano-urchin (SGNU) particles. Kinetic control of crystallization, fast mass transfer as well as a bumped surface morphology of the silica particles are important factors for the growth of gold branches on the silica support. Using a microfluidic platform, continuous synthesis of SGNUs is achieved with increased reaction rate (less than 12 min of residence time), better controllability and reproducibility than that obtained in batch synthesis. The hyper-branched gold structures display surface-enhanced Raman scattering (SERS).Compared to freestanding nanoparticles, supported nanostructures typically show better mechanical stability as well as ease of handling. Unique shapes such as core-shells, raspberries and crescents have been developed on supported materials to gain improved chemical and optical properties along with versatility and tunability. We report the formation of hyper-branched gold structures on silica particles, silica-gold nano-urchin (SGNU) particles. Kinetic control of crystallization, fast mass transfer as well as a bumped surface morphology of the silica particles are important factors for the growth of gold branches on the silica support. Using a microfluidic platform, continuous synthesis of SGNUs is achieved with increased reaction rate (less than 12 min of residence time), better controllability and reproducibility than that obtained in batch synthesis. The hyper-branched gold structures display surface-enhanced Raman scattering (SERS). Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04021j

  6. Effect of Silica Ratio on the Corrosion Behavior of Nano-silica Potassium Silicate Coatings on Aluminum Alloy 2024

    NASA Astrophysics Data System (ADS)

    Bahri, H.; Danaee, I.; Rashed, G. R.; Zaarei, D.

    2015-02-01

    Nano-silica modified potassium silicate conversion coating was deposited in different nano-silica/potassium silicate ratios on the surface of 2024 aluminum alloy. The corrosion behavior of coatings was studied by electrochemical impedance spectroscopy, current transient, potentiodynamic polarization, and surface techniques. The ratio of nano-silica/potassium silicate was optimized in order to obtain higher corrosion protection. The experimental results indicated that with increasing nano-silica/potassium silicate ratio, the corrosion resistance of aluminum increases. Furthermore, the pitting corrosion probability of potassium silicate conversion coating decreased with increasing silica ratio. This can be related to the size of nano-silica particles and the ability to fill the pores in potassium silicate coating and reinforce the created siloxane bridges.

  7. Comparison of dielectric properties of polydimethylsiloxane (PDMS) grafted polyacrylates/nano alumina and nano silica composites

    NASA Astrophysics Data System (ADS)

    Murudkar, Vrishali V.; Gaonkar, Amita A.; Deshpande, V. D.; Mhaske, S. T.

    2016-05-01

    Polydimethylsiloxane possess very poor mechanical properties. However, typically the initial modulus and durability of material is low and to improve this aspect a reinforcement phase is required. For the composite to be effective the filler must be with large aspect ratio i.e. with large surface area to volume ratio. Nano alumina (Al2O3) and nano silica (SiO2) are materials of choice for nanocomposite design. Grafted Polydimethylsiloxane (G-PDMS) and nano alumina and nano Silica composites have been prepared, by solvent casting method. FTIR study reveals that there is bonding overlap in G-PDMS/SiO2 nano composites. In dielectric study, it is observed that G-PDMS/SiO2 nano composites were more conducting in nature than G-PDMS/ Al2O3 nano composites. G-PDMS/ Al2O3 nano composites showed enhanced dielectric constant and less loss of energy than G-PDMS/SiO2 nano composites.

  8. Thick multilayered (silica/gold) dipole nano-antenna.

    PubMed

    Khaleque, Abdul; Mironov, Evgeny G; Liu, Liming; Hattori, Haroldo T

    2015-12-01

    Nano-antennas are the optical equivalent of antennas that are used to transmit and receive information at radio frequencies. These antennas have been used in different applications in photonics such as optical imaging, particle manipulation, bio-sensing, and improvement of the performance of solar cells. In this article we study composite nano-antennas made of alternating layers of silica and gold. We show that a 50% filling factor leads to a 2.0 times increase in the electric-field enhancement factor when compared with a pure-gold antenna. PMID:26836661

  9. Effect of catalyst concentration on size, morphology and optical properties of silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Arora, Ekta; Ritu, Kumar, Sacheen; Kumar, Dinesh

    2016-05-01

    Today, nanomaterials play a key role in various fields such as electronics, aerospace, pharmaceuticals and biomedical because of their unique physical, chemical and biological properties which are different from bulk materials. Nano sized silica particles have gained the prominent position in scientific research and have wide applications. The sol-gel method is the best method to synthesize silica nanoparticles because of its potential to produce monodispersed with narrow size distribution at mild conditions. The silica nanoparticles were obtained by hydrolysis of tetraethyl orthosilicate (TEOS) in ethanol act as solvent. The synthesized nanoparticles were characterized by Field Emission Scanning electron Microscope (FE-SEM), UV Spectrometer. The smallest size of silica particles is around 150nm examined by using FE-SEM. The optical properties and band structure was analyzed using UV-visible spectroscopy which is found to be increase by reducing the size of particles. Concentration effect of catalyst on the size, morphology and optical properties were analyzed.

  10. Pore morphology study of silica aerogels

    SciTech Connect

    Hua, D.W.; Anderson, J.; Haereid, S.; Smith, D.M.

    1994-12-31

    Silica aerogels have numerous properties which suggest applications such as ultra high efficiency thermal insulation. These properties relate directly to the aerogel`s pore size distribution. The micro and meso pore size ranges can be investigated by normal small angle x-ray scattering and possibly, nitrogen adsorption. However, the measurement of larger pores (> 250 {angstrom}) is more difficult. Due to their limited mechanical strength, mercury porosimetry and nitrogen condensation can disrupt the gel structure and electron microscopy provides only limited large scale structure information. The use of small angle light scattering techniques seems to have promise, the only hurdle is that aerogels exhibit significant multiple scattering. This can be avoided if one observes the gels in the wet stage since the structure of the aerogel should be very similar to the wet gel (as the result of supercritical drying). Thus, if one can match the refractive index, the morphology can be probed. The combination of certain alcoholic solvents fit this index matching criteria. Preliminary results for the gel network (micron range) and primary particle structure (manometer) are reported by using small angle light scattering and ultra-small angle x-ray scattering. The effects on structure over the length scale range of <1 nm to >5 {mu}m under different conditions (precursors, pH, etc.) are presented. The change in structure of an aerogel during isostatic compaction to 228 MPa (to simulate drying from wetting solvents) are also discussed.

  11. Conductive polyurethane composites containing polyaniline-coated nano-silica.

    PubMed

    Liu, Bo-Tau; Syu, Jhan-Rong; Wang, De-Hua

    2013-03-01

    In this study, we used 1.2-Aminopropyltriethoxysilane (APTS) as a coupling agent to synthesize silica-polyaniline (PANI) core-shell nanoparticles. The core-shell nanoparticles and PANI oligomers were reacted with isocyanates to prepare the conductive polyurethane (PU)-PANI-silica nanocomposites. The core-shell-nanoparticle structure shows significant enhancement on electrical properties of the conductive nanocomposites even though only 0.0755-wt.% PANI was coated on the nano-silica. The surface resistance of the nanocomposite containing 5 wt.% PANI can reduce to ~10(8) Ω/sq, lowering two orders in contrast to the nanocomposite without the core-shell structure. In comparison with the neat PU, tensile strength and elongation of the nanocomposite containing silica-PANI core-shell nanoparticles can increase 3.1 and 3.8 times, respectively. We suspect that the extraordinary enhancement of electrical and mechanical properties may result from the fact that contact probability among PANI moieties and chemical bonding between particles and PU matrix increase due to the PANI coated on the surface of silica. PMID:23261334

  12. The use of Reactive Ion Etching for obtaining “free” silica nano test tubes

    NASA Astrophysics Data System (ADS)

    Buyukserin, Fatih; Martin, Charles R.

    2010-10-01

    Silica nano test tubes are one-dimensional inorganic nanostructures with several biotechnological applications including biosensing, magnetic resonance imaging, and targeted cancer therapeutics. They are generally prepared by sol-gel deposition of silica to nanoporous alumina templates. Preparing samples composed of isolated free silica nano test tubes can be a challenging process due to the conformal coating of silica on the template. This causes the formation of a top-surface silica layer which laterally connects the nano test tubes. Herein, we detailed the use of Reactive Ion Etching to remove this top-surface silica layer which yields free silica nano test tubes with template dissolution. Compared with the mechanical polishing approach, Reactive Ion Etching treatment allows a fine manipulation ability of the surface material at the nanoscale level. When used excessively, Reactive Ion Etching causes an orifice closing phenomenon that may be employed to create novel one-dimensional nanocapsules.

  13. Species-specific polyamines from diatoms control silica morphology

    NASA Astrophysics Data System (ADS)

    Kröger, Nils; Deutzmann, Rainer; Bergsdorf, Christian; Sumper, Manfred

    2000-12-01

    Biomineralizing organisms use organic molecules to generate species-specific mineral patterns. Here, we describe the chemical structure of long-chain polyamines (up to 20 repeated units), which represent the main organic constituent of diatom biosilica. These substances are the longest polyamine chains found in nature and induce rapid silica precipitation from a silicic acid solution. Each diatom is equipped with a species-specific set of polyamines and silica-precipitating proteins, which are termed silaffins. Different morphologies of precipitating silica can be generated by polyamines of different chain lengths as well as by a synergistic action of long-chain polyamines and silaffins.

  14. Synthesis and biological response of casein-based silica nano-composite film for drug delivery system.

    PubMed

    Ma, Jianzhong; Xu, Qunna; Zhou, Jianhua; Zhang, Jing; Zhang, Limin; Tang, Huiru; Chen, Lihong

    2013-11-01

    Casein possesses many interesting properties that make it a good candidate for conventional and novel drug delivery systems. In this study, casein-based silica nano-composite was prepared via double in situ method, and the as-prepared latex particles were evaluated in terms of their morphology and size through transmission electron microscopy (TEM). The film morphology was investigated by scanning electron microscopy (SEM) and energy dispersive X-ray (EDX), and the mechanical property and response behavior of the films as a function of silica content were discussed. Ibuprofen was used as the model drug. The drug load and release properties were studied by solid-state nuclear magnetic resonance (solid-state NMR), Fourier transform infrared (FT-IR), SEM and in vitro test. The composite latex particle showed a stable core-shell structure, and the film exhibited a regular surface with even SiO2 distribution. The drug load efficiency of the composite films increased with adding silica because of the adsorption of the drugs on the silica. In an acidic release medium, the ibuprofen-loaded composite showed a slower drug release dependent on the silica content. These behaviors were most likely due to the reduced diffusion rate of the drug through the composite microsphere, which resulted from the interaction between the silica and the drug. PMID:23831671

  15. Use of polypropylene fibers coated with nano-silica particles into a cementitious mortar

    NASA Astrophysics Data System (ADS)

    Coppola, B.; Di Maio, L.; Scarfato, P.; Incarnato, L.

    2015-12-01

    Fiber reinforced cementitious composite (FRCC) materials have been widely used during last decades in order to overcome some of traditional cementitious materials issues: brittle behaviour, fire resistance, cover spalling, impact strength. For composite materials, fiber/matrix bond plays an important role because by increasing fiber/matrix interactions is possible to increase the behaviour of the entire material. In this study, in order to improve fiber to matrix adhesion, two chemical treatments of polypropylene fibers were investigated: alkaline hydrolysis and nano-silica sol-gel particles deposition. Treatmtents effect on fibers morphology and mechanical properties was investigated by scanning electron microscopy (SEM) and tensile tests. SEM investigations report the presence of spherical nano-silica particles on fiber surface, in the case of sol-gel process, while alkaline hydrolysis leads to an increase of fibers roughness. Both treatments have negligible influence on fibers mechanical properties confirming the possibility of their use in a cementitious mortar. Pullout tests were carried out considering three embedded length of fibers in mortar samples (10, 20 and 30 mm, respectively) showing an increase of pullout energy for treated fibers. The influence on fiber reinforced mortar mechanical properties was investigated by three-point flexural tests on prismatic specimens considering two fibers length (15 and 30 mm) and two fibers volume fractions (0.50 and 1.00 %). A general increase of flexural strength over the reference mix was achieved and an overall better behaviour is recognizable for mortars containing treated fibers.

  16. Use of polypropylene fibers coated with nano-silica particles into a cementitious mortar

    SciTech Connect

    Coppola, B. Di Maio, L.; Scarfato, P.; Incarnato, L.

    2015-12-17

    Fiber reinforced cementitious composite (FRCC) materials have been widely used during last decades in order to overcome some of traditional cementitious materials issues: brittle behaviour, fire resistance, cover spalling, impact strength. For composite materials, fiber/matrix bond plays an important role because by increasing fiber/matrix interactions is possible to increase the behaviour of the entire material. In this study, in order to improve fiber to matrix adhesion, two chemical treatments of polypropylene fibers were investigated: alkaline hydrolysis and nano-silica sol-gel particles deposition. Treatmtents effect on fibers morphology and mechanical properties was investigated by scanning electron microscopy (SEM) and tensile tests. SEM investigations report the presence of spherical nano-silica particles on fiber surface, in the case of sol-gel process, while alkaline hydrolysis leads to an increase of fibers roughness. Both treatments have negligible influence on fibers mechanical properties confirming the possibility of their use in a cementitious mortar. Pullout tests were carried out considering three embedded length of fibers in mortar samples (10, 20 and 30 mm, respectively) showing an increase of pullout energy for treated fibers. The influence on fiber reinforced mortar mechanical properties was investigated by three-point flexural tests on prismatic specimens considering two fibers length (15 and 30 mm) and two fibers volume fractions (0.50 and 1.00 %). A general increase of flexural strength over the reference mix was achieved and an overall better behaviour is recognizable for mortars containing treated fibers.

  17. Research on Water Based Coating Containing Nano-Silica for Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Zheng, Tianliang; Li, Di

    Due to magnesium's active chemical property, a novel environmental protective water based metallic coating was developed, which mainly contains metal flake, nano-silica, silicate and silane. The coating's properties were investigated by neutral salt spray test, micro-hardness testing, adhesion test and electrochemical technique etc. Meanwhile the coating surface and microstructure was observed by scanning electron microscopy (SEM). Furthermore, the effect of nano silica on the coating was also explored. Results showed that an excellent adhesive, heat-resisting, protective coating for AZ91D magnesium alloy could be achieved by this technique. It also indicated that nano silica could greatly improve the properties of coating. In the paper, mechanism of nano silica coating was also discussed.

  18. Development of construction materials using nano-silica and aggregates recycled from construction and demolition waste.

    PubMed

    Mukharjee, Bibhuti Bhusan; Barai, Sudhirkumar V

    2015-06-01

    The present work addresses the development of novel construction materials utilising commercial grade nano-silica and recycled aggregates retrieved from construction and demolition waste. For this, experimental work has been carried out to examine the influence of nano-silica and recycled aggregates on compressive strength, modulus of elasticity, water absorption, density and volume of voids of concrete. Fully natural and recycled aggregate concrete mixes are designed by replacing cement with three levels (0.75%, 1.5% and 3%) of nano-silica. The results of the present investigation depict that improvement in early days compressive strength is achieved with the incorporation of nano-silica in addition to the restoration of reduction in compressive strength of recycled aggregate concrete mixes caused owing to the replacement of natural aggregates by recycled aggregates. Moreover, the increase in water absorption and volume of voids with a reduction of bulk density was detected with the incorporation of recycled aggregates in place of natural aggregates. However, enhancement in density and reduction in water absorption and volume of voids of recycled aggregate concrete resulted from the addition of nano-silica. In addition, the results of the study reveal that nano-silica has no significant effect on elastic modulus of concrete. PMID:25986048

  19. Synthesis of ordered mesoporous silica and alumina with controlled macroscopic morphologies

    NASA Astrophysics Data System (ADS)

    Alsyouri, Hatem Mohammad Sadi

    The ability to synthesize nanostructured inorganic materials with controlled microstructural and morphological features will provide materials with unique characteristics in unprecedented ways. This thesis investigates the synthesis of porous silica and alumina materials with controlled microstructures and desirable shapes using novel approaches based on template-assisted synthesis and chemical vapor deposition (CVD) techniques. It primarily focuses on fabricating mesoporous materials with unique microstructures and different morphologies (particles and membranes) and exploring the potential of the particle morphology in a polymer reaction application. The template-assisted growth of mesoporous silica under acidic and quiescent conditions at an oil-water interface can generate mesostructured silica at the interface with fibrous, gyroidal, spherical, and film morphologies. Synthesis conditions can be used to alter the growth environment and control the product morphology. Fiber morphology is obtained at narrow range of experimental conditions due to slow and one-dimensional diffusion of silicon alkoxide through the interface. Variation in these conditions can alter the axial growth of silica and yield non-fibrous shapes. The fibers grow from their base attached to the interface and coalesce to form fibers with larger diameters. Gas transport in the mesoporous silica fibers is governed by combination of Knudsen and surface diffusion mechanisms. Surface diffusion contributes to 40% of the net flow reflecting a highly smooth pore surfaces. Real Knudsen and surface diffusivities are in the order of 10-3 and 10 -5 cm2/s respectively. The one-dimensional mesopores are 45 time longer than the macroscopic fiber length and align helically around the fiber axis, confirming the literature observations, with a pitch value of 1.05 micron. For preparation of mesoporous silica materials as membranes, a novel counter diffusion self assembly (CDSA) approach is demonstrated. This

  20. Vital roles of nano silica in synthetic based mud for high temperature drilling operation

    NASA Astrophysics Data System (ADS)

    Yusof, Muhammad Aslam Md; Hanafi, Nor Hazimastura

    2015-07-01

    At high temperature drilling, chemicals degradation occurs which reduce the effectiveness of the drilling fluid. There is a potential that by using nano sized particles which have thermal stability up to 2500°F to be used as a stabilizer to withstand the harsh condition. Therefore, this project aims to identify the performance of synthetic-based mud (SBM) with nano silica for high temperature drilling operation. A conventional SBM performance has been compared with additional percentages of nano silica. 20% and 40% of nano silica out of fluid loss weight has been added into the SBM and analyzed the rheological properties and other drilling fluid properties. The conventional SBM formulation has lost some amount of weighting material or solids in the mud and has been replaced by lighter and smaller size of nanoparticles. It has reduced the rheological properties of the mud but the gelation formed by nano silica material has given higher gel strength. Also, nano silica potentially plugs the porous media, resulted in lower filtration loss measurement and thinner mud cake ranged 20% to 50% respectively.

  1. Morphological characterization of silica obtained by calcination of methacrylic and epoxy - silica hybrid systems

    NASA Astrophysics Data System (ADS)

    Tescione, F.; Lionetto, F.; Corcione, C. Esposito; Buonocore, G. G.; Striani, R.; Lavorgna, M.; Frigione, M.

    2016-05-01

    The work is addressed to investigating the potentiality of calcination of organic-inorganic (O-I) hybrids as a feasible approach to produce silica particles, at mild temperature conditions and with tailored morphology. Two different innovative hybrid systems were obtained through sol-gel process with a siloxane content ranging from 6 to 26wt%. The two O-I hybrids differed for i) the organic matrix (methacrylic or epoxy), ii) its crosslinking mechanism (photopolymerization for methacrylic systems or thermal cold-cure for epoxy systems) and iii) the rate ratio between sol-gel and crosslinking reactions. Different characterization techniques were used to understand the effect of composition and curing method on the morphology of the silica obtained from O-I hybrids after calcination in air. The results confirm the morphology and properties of silica particles in terms of surface and porosity may be tailored over a wide range by varying the composition and nature of organic and inorganic precursors of hybrids.

  2. Probabilistic modeling of the flows and environmental risks of nano-silica.

    PubMed

    Wang, Yan; Kalinina, Anna; Sun, Tianyin; Nowack, Bernd

    2016-03-01

    Nano-silica, the engineered nanomaterial with one of the largest production volumes, has a wide range of applications in consumer products and industry. This study aimed to quantify the exposure of nano-silica to the environment and to assess its risk to surface waters. Concentrations were calculated for four environmental (air, soil, surface water, sediments) and two technical compartments (wastewater, solid waste) for the EU and Switzerland using probabilistic material flow modeling. The corresponding median concentration in surface water is predicted to be 0.12 μg/l in the EU (0.053-3.3 μg/l, 15/85% quantiles). The concentrations in sediments in the complete sedimentation scenario were found to be the largest among all environmental compartments, with a median annual increase of 0.43 mg/kg · y in the EU (0.19-12 mg/kg · y, 15/85% quantiles). Moreover, probabilistic species sensitivity distributions (PSSD) were computed and the risk of nano-silica in surface waters was quantified by comparing the predicted environmental concentration (PEC) with the predicted no-effect concentration (PNEC) distribution, which was derived from the cumulative PSSD. This assessment suggests that nano-silica currently poses no risk to aquatic organisms in surface waters. Further investigations are needed to assess the risk of nano-silica in other environmental compartments, which is currently not possible due to a lack of ecotoxicological data. PMID:26745294

  3. Controlling particle deposit morphologies in drying nano-particle laden sessile droplets using substrate oscillations.

    PubMed

    Sanyal, Apratim; Basu, Saptarshi; Chaudhuri, Swetaprovo

    2016-06-01

    Sessile water droplets containing nano-silica particles are allowed to evaporate in the presence of driven substrate oscillations at chosen frequencies. Different mode shapes are observed at different oscillation frequencies. As reference, the evaporation of the same droplets is also observed under stationary conditions i.e. in the absence of any oscillations. For all cases, the deposit structures formed by the agglomeration of the nano-silica particles have been imaged. It has been observed that for the stationary droplets and for droplets whose oscillations are initiated close to the resonance of the lowest allowable oscillation mode, the structures are similar having larger spread over height, while for higher frequencies the structures are dome-like with more uniform outer dimensions. The possible reasons behind these structures are investigated using experimental techniques such as high-speed imaging of droplet oscillations, internal flow visualization and SEM imaging. Understanding of the underlying mechanisms behind the formation of these striking features is required for these methods to be applicable in larger scale drying operations or micro-device applications. Altogether a novel methodology has been presented and investigated for manipulating the morphological features in evaporating nano-particle laden sessile droplets. PMID:27181754

  4. Morphological Control of Multifunctional Mesoporous Silica Nanomaterials for Catalysis Applications

    SciTech Connect

    Seong Huh

    2004-12-19

    I found an efficient method to control the morphology of the organically monofunctionalized mesoporous silica materials by introducing different types of organoalkoxysilanes in a base-catalyzed co-condensation reaction. The monofunctionalized materials exhibit different particle morphologies relative to the pure MCM-41 material. The concentration dependence of the morphology is a critical factor to determine the final particle shape. A proposed mechanism of the shape evolution is also offered. After understanding the role of organoalkoxysilanes in producing various well-shaped nanomaterials, I also obtained a series of bifunctional mesoporous silica materials with certain particle morphology. A series of bifunctional mesoporous silica nanospheres (MSNs) whose physicochemical properties was investigated via solid state NMR techniques and Cu{sup 2+} adsorption capacity tests, The ratio of two different organic groups inside of mesopores of these MSNs could be fine-tuned. These MSNs serve as a useful model system to study substrate selectivity in catalytic reactions and sorption phenomena. For example, the Cu{sup 2+} adsorption capacity of these materials was dictated by the chemical nature of the mesopores generated by the different organic functional groups. An investigation of the substrate selectivity of the bifunctionalized MSNs in a competitive nitroaldol reaction using an equimolar amount of two competing 4-nitrobenzaldehyde derivatives was performed. Shape-controlled bifunctional MSNs were employed as the catalysts. The properties of the MSNs were investigated using various spectroscopic methods and electron microscopy. The more hydrophobic the surface organic groups are, the higher the ratio of hydrophobic final product. This is the first example to demonstrate the selection of substrate using physicochemical nature of the mesopore surface other than the conventional shape selection in zeolite systems. I also created a cooperative dual catalyst system that is

  5. Morphological control of multifunctionalized mesoporous silica nanomaterials for catalysis applications

    NASA Astrophysics Data System (ADS)

    Huh, Seong

    I found an efficient method to control the morphology of the organically monofunctionalized mesoporous silica materials by introducing different types of organoalkoxysilanes in a base-catalyzed co-condensation reaction. The monofunctionalized materials exhibit different particle morphologies relative to the pure MCM-41 material. The concentration dependence of the morphology is a critical factor to determine the final particle shape. A proposed mechanism of the shape evolution is also offered. After understanding the role of organoalkoxysilanes in producing various well-shaped nanomaterials, I also obtained a series of bifunctional mesoporous silica materials with certain particle morphology. A series of bifunctional mesoporous silica nanospheres (MSNs) whose physicochemical properties was investigated via solid state NMR techniques and Cu 2+ adsorption capacity tests. The ratio of two different organic groups inside of mesopores of these MSNs could be fine-tuned. These MSNs serve as a useful model system to study substrate selectivity in catalytic reactions and sorption phenomena. For example, the Cu2+ adsorption capacity of these materials was dictated by the chemical nature of the mesopores generated by the different organic functional groups. An investigation of the substrate selectivity of the bifunctionalized MSNs in a competitive nitroaldol reaction using an equimolar amount of two competing 4-nitrobenzaldehyde derivatives was performed. Shape-controlled bifunctional MSNs were employed as the catalysts. The properties of the MSNs were investigated using various spectroscopic methods and electron microscopy. The more hydrophobic the surface organic groups are, the higher the ratio of hydrophobic final product. This is the first example to demonstrate the selection of substrate using physicochemical nature of the mesopore surface other than the conventional shape selection in zeolite systems. I also created a cooperative dual catalyst system that is capable of

  6. Self-Assembled Silica Nano-Composite Polymer Electrolytes: Synthesis, Rheology & Electrochemistry

    SciTech Connect

    Khan, Saad A.: Fedkiw Peter S.; Baker, Gregory L.

    2007-01-24

    The ultimate objectives of this research are to understand the principles underpinning nano-composite polymer electrolytes (CPEs) and facilitate development of novel CPEs that are low-cost, have high conductivities, large Li+ transference numbers, improved electrolyte-electrode interfacial stability, yield long cycle life, exhibit mechanical stability and are easily processable. Our approach is to use nanoparticulate silica fillers to formulate novel composite electrolytes consisting of surface-modified fumed silica nano-particles in polyethylene oxides (PEO) in the presence of lithium salts. We intend to design single-ion conducting silica nanoparticles which provide CPEs with high Li+ transference numbers. We also will develop low-Mw (molecular weight), high-Mw and crosslinked PEO electrolytes with tunable properties in terms of conductivity, transference number, interfacial stability, processability and mechanical strength

  7. Enhancement of impact strength of poly (methyl methacrylate) with surface fine-tuned nano-silica

    NASA Astrophysics Data System (ADS)

    Wen, Bin; Dong, Yixiao; Wu, Lili; Long, Chao; Zhang, Chaocan

    2015-07-01

    Highly dispersible nanoparticles in organic solvent always receive wide interests due to their compatibility with polymer materials. This paper reported a kind of isopropanol alcohol silica dispersion which obtained using a method of azeotropic distillation. The isopropanol alcohol dispersed silica (IPADS) were treated with coupling agents to fine-tune their surface properties. Polymethyl methacrylate (PMMA) was then used as a research object to test the compatibility between IPADS and polymer. UV-vis spectra indicate that IPADS would reach its high compatibility with PMMA if coupling with trimethoxypropylsilane (PTMS). Followed experiments on PMMA proved that the high compatibility can prominently enhance the impact strength about 30%. The results may provide reference both for nano-silica modification and better understanding of nano-enhanced materials.

  8. Controllable synthesis of hollow mesoporous silica spheres and application as support of nano-gold

    SciTech Connect

    Wang, Tao; Ma, Weihua Shangguan, Junnan; Jiang, Wei; Zhong, Qin

    2014-07-01

    Hollow silica spheres with mesoporous structure were synthesized by sol–gel/emulsion method. In the process, the surfactant, cetyltrimethylammonium bromide (CTAB) was used to stabilize the oil droplet and also used as structure direct agent. The diameter of the hollow silica spheres, ranging from 895 nm to 157 nm, can be controlled by changing the ratio of ethanol to water and the concentration of the surfactant as well. The shell thickness of the spheres decreased when the ratio of ethanol to water decreased. The proposed mechanism of the formation of silica spheres could elucidate the experimental results well. Furthermore, the resultant hollow mesoporous silica spheres were then employed as support of nano-gold which was used to catalyze the isomerization reaction of propylene oxide to produce allyl alcohol. - Graphical abstract: It is the schematic mechanism for the formation of hollow mesoporous silica spheres. - Highlights: • The formation mechanism of the hollow spheres is proposed. • The isomerization of propylene oxide can be catalyzed by the nano-gold/SiO{sub 2}. • The hollow silica spheres can be prepared controllably.

  9. Effect of nano-silica spheres template on CO2 capture of exchange resin-based nanoporous carbons.

    PubMed

    Meng, Long-Yue; Park, Soo-Jin

    2013-01-01

    In this work, a nanoporous carbon-based adsorbent with a higher specific surface area was directly prepared from polystyrene-based cation exchange resin (PCER) by carbonization of a mixture of nano-silica spheres. The silica/PCER composites were carbonized at 1173 K with different silica/PCER ratios. The effects of nano-silica spheres content on the pore structures of nanoporous carbons were investigated by N2 full isotherms. The CO2 capture capacity was measured by CO2 isothermal adsorption at 298 K and 1 bar. From the results, it was found that the nano-silica spheres/PCER ratio had a major influence on the CO2 capture capacity and the textural properties of the prepared nanoporous carbons. The specific surface area and total pore volume, as well as the pore size of the nanoporous carbons increased with increasing silica/PCER ratio. PMID:23646745

  10. Silica fertilization and nano-MnO₂ amendment on bacterial community composition in high arsenic paddy soils.

    PubMed

    Shao, Jihai; He, Yaxian; Zhang, Huiling; Chen, Anwei; Lei, Ming; Chen, Junfeng; Peng, Liang; Gu, Ji-Dong

    2016-03-01

    Silica fertilization and nano-MnO2 amendment are reported as useful approaches in lowering the accumulation of arsenic in rice grains, but the effects of silica fertilization or nano-MnO2 amendment on microbial community in the paddy soils containing high concentration of arsenic are still unknown. In order to elucidate this question, the structures and composition of microbial community in the paddy soils, in response to silica fertilization and nano-MnO2 amendment, were investigated using pyrosequencing technique. The results indicated that Proteobacteria, Chloroflexi, and Acidobacteria were the main dominating phyla in these paddy soils. A decrease in the relative abundance of Chloroflexi and Cyanobacteria, but an increase in the relative abundance of Acidobacteria was observed after silica fertilization and nano-MnO2 amendment. The changes of Acidobacteria, Chloroflexi, and Cyanobacteria were strongly correlated with pH and the concentration of bioavailable arsenic in the paddy soils. The α-diversity of bacteria in the paddy soils increased in response to silica fertilization at low amendment level, but decreased under silica or nano-MnO2 amendment at high amendment level. Results of β-diversity analysis indicated that the microbial communities in the control treatment shared more similarity with that of those received low level of nano-MnO2 amendment, and the two silica fertilization treatments also shared more similarity with each other. PMID:26563550

  11. Electrodeposition of macroporous nickel coating by employing nano-silica as template.

    PubMed

    Xu, Lijian; Chen, Baizhen; Du, Jingjing

    2012-09-01

    A novel method of preparing the macrporous nickel coating was described. The macrporous nickel coating was fabricated by employing nano-silica as the template. The effects of technological conditions and the concentration of the additives on the surface quality of coating were investigated, the nano-silica was characterized transmission electron microscopy (TEM) and laser particle size analyzer, and the macrporous nickel coating was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The experimental results showed that nano-silica particles were about 100 nm, the optimal technological conditions of electrodepositing nickel were that the cathode current density was 12 A/dm2, the temperature was 30 degrees C and the pH value was 2.0, the concentration of lauryl sodium sulfate was 0.15 g/L and the concentration of glucide was 3 g/L, the macrporous nickel coating was obtained when the adding nano-SiO2 content in the electroplating bath was 6 g/L and its structure was crystalline. PMID:23035461

  12. Tennis core strings of polyamide-6 modified by surface-capped nano-silica

    NASA Astrophysics Data System (ADS)

    Liu, Juan; Yi, Hongling; Lin, Heng; Zheng, Baicun

    2013-01-01

    A new method that modified silica nanoparticles were infused into PA6 is to produce tennis core string through a melt-extrusion process. The idea was to produce a highly strong and elastic tennis core string of PA6, utilizing the interactions between modified silica and polymer. The effects of surface-capped nano-silica on the strength and elongation of tennis core string were studied. It has been observed that with the infusion of silica nanoparticles modified by γ-glycidoxypropyltrimethoxysilane (GPS), the stress at breaking and E-modulus of tennis core string is enhanced by 46.24% and 15.17% comparing with neat PA6 with changeless elongation at breaking at a critical concentration. The source of this improvement has been traced to the produced strong covalent bond and hydrogen bond between epoxy groups and-COOH and-NH2 in polyamide. Besides, compared with kinds of others strings of previous research results, tennis core string added nano-silica modified by γ-glycidoxypropyltrimethoxysilane (GPS) has a strength at breaking at 352.43 MPa exceeding the natural gut string, the polyvinylidene fluoride (PVDF), Monofil string and integrated nylon string by 42.05%, 4.49% and 9.38%, respectively. Meanwhile, tennis core string of polyamide modified by surface-capped nanosilica (PGMNS) has a higher elastic ratio at 0.15 than the other four strings.

  13. Dielectric behavior of Silica/Poly(dimethylsiloxane) nanocomposites. nano size effects

    NASA Astrophysics Data System (ADS)

    Ibrahim, I. A. M.; Zikry, A. A. F.; Sharaf, M. A.; Mark, J. E.; Jacob, K.; Jasiuk, I. M.; Tannenbaumn, R.

    2012-09-01

    The enhancement of properties of elastomeric composite materials is very much dependent on the size and the surface modification of the reinforcing filler inclusions. It is well accepted that the reinforcement effects are primarily due to molecular interactions of the polymeric matrix and the filler inclusions and it involves both chemical and physical interactions. In the present study, we have incorporated silica nano fillers (Stober silica) into poly(dimethylsiloxane) (PDMS) elastomeric networks. The dielectric properties of the networks were investigated as a function of filler nano filler size, volume fraction, and surface treatment by hexamethyldisilazane. The broad-spectrum dielectric properties (in particular, the dielectric constant, the dielectric loss, and tan δ) were characterized. These properties were found to be dependent on the size of the nano inclusions; thus, the results clearly showed a nano size phenomenon that was a highlight of the present research. Certainly, that can be largely attributed to the high specific surface area of the nano fillers, which significantly leads to a pronounced increase in interfacial interactions. Also, and as would be expected, the dielectric properties of the polymeric networks filled with unmodified particles were different from those for the polymeric networks filled with surface-modified particles. Again, this is mainly attributed to changes in the surface properties. The expected dependence of properties of the nanocomposite networks on the nature of the filler and its concentration has thus been demonstrated.

  14. Dispersion Morphology of Poly(methyl acrylate)/Silica Nanocomposites

    SciTech Connect

    D Janes; J Moll; S Harton; C Durning

    2011-12-31

    Nearly monodisperse poly(methyl acrylate) (PMA) and spherical SiO{sub 2} nanoparticles (NP, d = 14 {+-} 4 nm) were co-cast from 2-butanone, a mutually good solvent and a displacer of adsorbed PMA from silica. The effects of NP content and post-casting sample history on the dispersion morphology were found by small-angle X-ray scattering supplemented by transmission electron microscopy. Analysis of the X-ray results show that cast and thermally annealed samples exhibited a nearly random particle dispersion. That the same samples, prior to annealing, were not well-dispersed is indicative of thermodynamic miscibility during thermal annealing over the range of NP loadings studied. A simple mean-field thermodynamic model suggests that miscibility results primarily from favorable polymer segment/NP surface interactions. The model also indicates, and experiments confirm, that subsequent exposure of the composites to the likely displacer ethyl acetate results in entropic destabilization and demixing into NP-rich and NP-lean phases.

  15. Morphology of the cross section of silica layer in rice husk.

    PubMed

    Byun, Sung Chun; Jung, In Ok; Kim, Moon Yong; So, Soo Jeong; Yoon, Chan; Kim, Chul; Lei, Guo; Han, Chong Soo

    2011-02-01

    The physical adsorption of nitrogen and gas flow experiments on the silica layer in rice husk indicated that an existence of nano meter sized through holes. In this study, the external shape of the holes on the cross section of the layer was investigated with a scanning electron microscope equipped with an energy dispersive spectrometer, an atomic force microscope and scanning tunneling microscope. In the energy dispersive mapping image, 2-5 micron thick silica layer under outer cellulose layer, silica nano particles in the middle cellulose layer and sub micron silica layer in inner cellulose layer were observed. The cross section of the layer showed 20 nm building units with approximately 100 nm convexities. The atomic force microscopic image also showed the approximately 100 nm convexities as well as a roughness of approximately 20 nm. When osmium was coated on the silica layer, the wells with 2 approximately 5 nm horizontal and approximately 2 nm vertical lengths were observed on the plate surface in scanning tunneling microscopic image. From the results, it was suggested that the holes in the rice husk silica layer are almost straight and not zigzag spaces originated from the simple packing of nano particles. PMID:21456176

  16. Molecular Dynamics Study on the Particle Dispersion Mechanism of Polyamide-imide/Silica Nano-composite Materials

    NASA Astrophysics Data System (ADS)

    Kikuchi, Hideyuki; Iwasaki, Tomio; Hanawa, Hidehito; Honda, Yuki

    We studied the particle dispersion mechanism of polyamide-imide/silica nano-composite material by using molecular-dynamics simulation technique based on Newtonian dynamics and quantum mechanics. In simulations, adhesive fracture energies at the interfaces between silica and solvents were calculated, and Brownian motions of silica particles were simulated to clarify dispersion properties. The simulation results showed that the colloidal state of silica was maintained by covering the silica surface with a new low hygroscopicity solvent and that the chemical structure of polymer contributed to the dispersion of silica. It is found that the results obtained from molecular dynamics agree well with those obtained by experiments, and that molecular-dynamics simulation technique will become very useful for the development of nano-composite materials in the future.

  17. Stability and geometry of silica nano-ribbons (SNRs): a first-principles study.

    PubMed

    Fang, C M; van Blaaderen, A; van Huis, M A

    2016-08-21

    Silica based materials are attractive because of their versatility and their unique structures and properties, which have led to numerous applications of silica in a range of fields. Recently, various low-dimensional silica materials have been synthesized experimentally. Here we present a first-principles study on the geometry and stability of novel low-dimensional silica nano-ribbons (SNRs) using density-functional theory (DFT) with van der Waals interactions (optB88-vdW). SNRs of various widths with different surface groups, and with the geometry of hexagonal rings and squares, were taken into consideration. An atomically flat ribbon with mixing squares and rings is also included. The calculations showed high stability for the single layer and bilayer silica ribbons, both containing hexagonal rings. The calculations also revealed a high flexibility of silica chains. The local structure and chemical bonding were carefully analyzed. Electronic band structure calculations showed an insulating nature of the SNRs with energy gaps of about 5.0 to 6.0 eV, which are determined by nonbonding and anti-bonding O 2p states. PMID:27436792

  18. Controlling the nano-bio interface to build collagen-silica self-assembled networks

    NASA Astrophysics Data System (ADS)

    Aimé, Carole; Mosser, Gervaise; Pembouong, Gaëlle; Bouteiller, Laurent; Coradin, Thibaud

    2012-10-01

    Bio-hybrid networks are designed based on the self-assembly of surface-engineered collagen-silica nanoparticles. Collagen triple helices can be confined on the surface of sulfonate-modified silica particles in a controlled manner. This gives rise to hybrid building blocks with well-defined diameters and surface potentials. Taking advantage of the self-assembling properties of collagen, collagen-silica networks are further built-up in solution. The structural and specific recognition properties of the collagen fibrils are well-preserved within the hybrid assembly. A combination of calorimetry, dynamic light scattering, zetametry and microscopy studies indicates that network formation occurs via a surface-mediated mechanism where pre-organization of the protein chains on the particle surface favors the fibrillogenesis process. These results enlighten the importance of the nano-bio interface on the formation and properties of self-assembled bionanocomposites.Bio-hybrid networks are designed based on the self-assembly of surface-engineered collagen-silica nanoparticles. Collagen triple helices can be confined on the surface of sulfonate-modified silica particles in a controlled manner. This gives rise to hybrid building blocks with well-defined diameters and surface potentials. Taking advantage of the self-assembling properties of collagen, collagen-silica networks are further built-up in solution. The structural and specific recognition properties of the collagen fibrils are well-preserved within the hybrid assembly. A combination of calorimetry, dynamic light scattering, zetametry and microscopy studies indicates that network formation occurs via a surface-mediated mechanism where pre-organization of the protein chains on the particle surface favors the fibrillogenesis process. These results enlighten the importance of the nano-bio interface on the formation and properties of self-assembled bionanocomposites. Electronic supplementary information (ESI) available: XPS

  19. Elastic behavior of silica/poly(dimethylsiloxane) nanocomposites: nano-size effects

    NASA Astrophysics Data System (ADS)

    Ibrahim, I. A. M.; Zikry, A. A. F.; Sharaf, M. A.; Mark, J. E.; Jacob, K.; Jasiuk, I. M.; Tannenbaumn, R.

    2012-09-01

    Elastomeric materials require the incorporation of reinforcing fillers in order to improve their mechanical properties. The enhancement of properties is very much dependent on the size and any surface modification of the reinforcing agent. It is widely accepted that the reinforcement effects are primarily due to molecular interactions of the polymeric matrix and the filler inclusions and it involves both chemical and physical interactions. Herein, we have incorporated silica nano fillers (Stober silica) into poly (dimethylsiloxane) (PDMS) elastomeric networks. The mechanical and swelling properties of the networks were investigated as a function of filler sizes (50, 130, and 170 nm), volume fraction of the filler inclusions, and surface treatment of the particles by were analyzed to give the Mooney-Rivlin constants 2C1 and 2C2. These properties were found to be dependent on the size of the nano inclusions. Thus, a nano size phenomenon had been discerned and was one of the highlights of this investigation. This phenomenon was largely attributed to the high specific surface area of the nano fillers used that leads to significant increase in the interfacial interactions. Also, and as would be expected, the properties of the polymeric networks filled with unmodified particles were different than those obtained for the polymeric networks filled with surface-modified particles. This has been primarily attributed to changes in the surface properties, and as would be expected, the elastic properties of the networks were thus shown to be strongly dependent on type and concentration.

  20. Synthesis and characterization of a multimode stationary phase: Congo red derivatized silica in nano-flow HPLC.

    PubMed

    Zhang, Yi; Zhang, Yan; Wang, Guan; Chen, Wujuan; He, Pingang; Wang, Qingjiang

    2016-02-01

    A novel Congo red (CR) derivatized silica stationary phase was prepared and packed into a fused silica capillary tube for nano-flow HPLC. A variety of analytes including poly-aromatic hydrocarbons, parabens, acids, sulfonamides, bases, and nucleosides were successfully separated using the CR. In comparison with commercial ODS columns, this new stationary phase has a different separation mechanism (hydrophobically-assisted ion-exchange), which was evident in the separation of benzoic acid derivatives and sulfonamides. The successful application of CR-bonded silica stationary phase in the HILIC and PALC modes demonstrates the effectiveness of this potential chromatographic material in nano flow HPLC. PMID:26646316

  1. Fabrication of electrospun silica-titania nanofibers with different silica content and evaluation of the morphology and osteoinductive properties.

    PubMed

    Wang, Xiaokun; Zhu, Jingxian; Yin, Ling; Liu, Shize; Zhang, Xin; Ao, Yingfang; Chen, Haifeng

    2012-12-01

    Ceramic-derived materials have shown enhanced osteogenic potential for bone tissue engineering applications. Silica is the major component of bioglass, and titania, the oxide complex of titanium, has been found to enhance osteoblast differentiation. In this study, three groups of sol-gel-derived silica-titania fibrous meshes with precursor ratios of Ti:Si = 7:3, 1:1, 3:7 were fabricated by electrospinning. The effects of silica content on the crystal phase and morphology of silica-titania hybrid nanofiber meshes were also analyzed by scanning electron microscopy, X-ray diffraction, and laser confocal microscopy. The osteogenic potential of the silica-titania meshes was evaluated by seeding mesenchymal stem cells (MSCs) on each mesh and determining cell number, osteodifferentiation markers, and osteopontin production over time. Our results show that cells proliferated throughout the mesh surfaces with similar morphology in all groups. Decreased cell proliferation was observed with the fiber meshes compared with glass controls, whereas cell differentiation toward osteoblast was enhanced on the mesh groups, especially on the Ti:Si = 7:3 group. These findings suggest that higher fiber diameter, degree of crystallization, and titania content of nanofibers can enhance osteodifferentiation of MSCs. PMID:22767362

  2. Critical review of the safety assessment of nano-structured silica additives in food.

    PubMed

    Winkler, Hans Christian; Suter, Mark; Naegeli, Hanspeter

    2016-01-01

    The development of nano-materials is viewed as one of the most important technological advances of the 21st century and new applications of nano-sized particles in the production, processing, packaging or storage of food are expected to emerge soon. This trend of growing commercialization of engineered nano-particles as part of modern diet will substantially increase oral exposure. Contrary to the proven benefits of nano-materials, however, possible adverse health effects have generally received less attention. This problem is very well illustrated by nano-structured synthetic amorphous silica (SAS), which is a common food additive since several decades although the relevant risk assessment has never been satisfactorily completed. A no observed adverse effect level of 2500 mg SAS particles/kg body weight per day was derived from the only available long-term administration study in rodents. However, extrapolation to a safe daily intake for humans is problematic due to limitations of this chronic animal study and knowledge gaps as to possible local intestinal effects of SAS particles, primarily on the gut-associated lymphoid system. This uncertainty is aggravated by digestion experiments indicating that dietary SAS particles preserve their nano-sized structure when reaching the intestinal lumen. An important aspect is whether food-borne particles like SAS alter the function of dendritic cells that, embedded in the intestinal mucosa, act as first-line sentinels of foreign materials. We conclude that nano-particles do not represent a completely new threat and that most potential risks can be assessed following procedures established for conventional chemical hazards. However, specific properties of food-borne nano-particles should be further examined and, for that purpose, in vitro tests with decision-making cells of the immune system are needed to complement existing in vivo studies. PMID:27287345

  3. Preparation of monodisperse polystyrene/silica core-shell nano-composite abrasive with controllable size and its chemical mechanical polishing performance on copper

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Wang, Haibo; Zhang, Zefang; Qin, Fei; Liu, Weili; Song, Zhitang

    2011-11-01

    Monodisperse silica-coated polystyrene (PS) nano-composite abrasives with controllable size were prepared via a two-step process. Monodisperse positively charged PS colloids were synthesized via polymerization of styrene by using a cationic initiator. In the subsequent coating process, silica formed shell on the surfaces of core PS particles via the ammonia-catalyzed hydrolysis and condensation of tetraethoxysilane. Neither centrifugation/water wash/redispersion cycle process nor surface modification or addition surfactant was needed in the whole process. The morphology of the abrasives was characterized by scanning electron microscope. Transmission electron microscope and energy dispersive X-ray analysis results indicated that silica layer was successfully coated onto the surfaces of PS particles. Composite abrasive has a core-shell structure and smooth surface. The chemical mechanical polishing performances of the composite abrasive and conventional colloidal silica abrasive on blanket copper wafers were investigated. The root mean square roughness decreases from 4.27 nm to 0.56 nm using composite abrasive. The PS/SiO2 core-shell composite abrasives exhibited little higher material removal rate than silica abrasives.

  4. Synthesis of nano-forsterite powder by making use of natural silica sand

    NASA Astrophysics Data System (ADS)

    Nurbaiti, Upik; Suud, Fikriyatul Azizah; Darminto, Triwikantoro, Zainuri, Mochamad; Pratapa, Suminar

    2016-02-01

    Nano-forsterite powder with natural silica sand and magnesium powder as the raw materials have been succesfully synthesized. The silica sand was purified followed by a coprecipitation process to obtain colloidal silica. The magnesium powder was dissolved in a chloric acid solution to obtain MgCl2 solution. The nanoforsterite powder was synthesised using a sol-gel method which included the mixing the colloidal silica and the MgCl2 solution with various aging and filtering processes. The samples were dried at 100 °C using a hot plate and then the dried powders were calcinated at 900 °C for 2 hours. The samples were characetised for their elements and phase compositions using X-ray Flourescence (XRF) and X-ray Diffraction (XRD) methods, respectively. The diffraction data were qualitatively analyzed using Match!2 software and quantitatively using Rietica software. The crystallite size was verified using Transmission Electron Microscopy (TEM). Results of XRD data analysis showed that the forsterite content reached up to 90.5% wt. The TEM average crystallite size was approximately 53(6) nm.

  5. Surface modification to produce hydrophobic nano-silica particles using sodium dodecyl sulfate as a modifier

    NASA Astrophysics Data System (ADS)

    Qiao, Bing; Liang, Yong; Wang, Ting-Jie; Jiang, Yanping

    2016-02-01

    Hydrophobic silica particles were prepared using the surfactant sodium dodecyl sulfate (SDS) as a modifier by a new route comprising three processes, namely, aqueous mixing, spray drying and thermal treatment. Since SDS dissolves in water, this route is free of an organic solvent and gave a perfect dispersion of SDS, that is, there was excellent contact between SDS and silica particles in the modification reaction. The hydrophobicity of the modified surface was verified by the contact angle of the nano-sized silica particles, which was 107°. The SDS grafting density reached 1.82 nm-2, which is near the highest value in the literature. The optimal parameters of the SDS/SiO2 ratio in the aqueous phase, process temperature and time of thermal treatment were determined to be 20%, 200 °C and 30 min, respectively. The grafting mechanism was studied by comparing the modification with that on same sized TiO2 particles, which indicated that the protons of the Brønsted acid sites on the surface of SiO2 reacted with SDS to give a carbocation which then formed a Si-O-C structure. This work showed that the hydrophilic surface of silica can be modified to be a hydrophobic surface by using a water soluble modifier SDS in a new modification route.

  6. Morphological and electronic properties of ultrathin crystalline silica epilayers on a Mo(112) substrate

    NASA Astrophysics Data System (ADS)

    Schroeder, T.; Giorgi, J. B.; Bäumer, M.; Freund, H.-J.

    2002-10-01

    Ultrathin crystalline silica layers grown on a Mo(112) substrate have been shown to be a useful silica model oxide support in surface science model catalyst studies. As the oxide support material plays an important role in the catalytic process, a multitechnique surface science study is presented to characterize the morphological and electronic properties of the heteroepitaxial system SiO2/Mo(112). The long-range order of the silica epilayer which grows commensurate with a c(2×2) surface unit mesh on the Mo(112) substrate is studied by low-energy electron diffraction (LEED). The defect structure of the silica epilayer is characterized in a spot profile analysis (SPA)-LEED study. Antiphase domain boundaries split the silica epilayer into an array of silica crystal grains whose average size and shape is determined. Aiming to prepare flat silica surfaces, the change in the surface roughness with progress in the film preparation is monitored in a combined SPA-LEED and scanning tunneling microscopy (STM) study and seen to influence also the Si-O stretching frequency in the infrared-reflection-absorption spectroscopy spectra. In STM images of the final silica film an average surface roughness of about 1 Å is detected. It is possible to visualize the silica film unit cell periodicity. A combined anger electron spectroscopy and ultraviolet photoelectron spectroscopy valence band study confirms the silica film stoichiometry and the growth of a 4:2 coordinated silica polymorph on the Mo(112) surface. These various surface science studies allow us to propose models for the growth and structure of the silica epilayer on the Mo(112) surface.

  7. Mesoporous Nano-Silica Serves as the Degradation Inhibitor in Polymer Dielectrics.

    PubMed

    Yang, Yang; Hu, Jun; He, Jinliang

    2016-01-01

    A new generation of nano-additives for robust high performance nanodielectrics is proposed. It is demonstrated for the first time that mesoporous material could act as "degradation inhibitor" for polymer dielectrics to sequestrate the electrical degradation products then restrain the electrical aging process especially under high temperature conditions, which is superior to the existing additives of nanodielectrics except further increasing the dielectric strength. Polyethylenimine (PEI) loaded nano-scaled mesoporous silica MCM-41 (nano-MS) is doped into the dielectric matrix to prepare the PP/MCM-41-PEI nanocomposites. PEI provides the amines to capture the electrical degradation products while the MCM-41 brackets afford large adsorption surface, bring down the activating temperature of the absorbent then enhance the absorptive capacity. The electrical aging tests confirm the contribution of the mesoporous structure to electrical aging resistance and FT-IR analysis of the electrical degraded regions demonstrates the chemical absorption especially under high temperature conditions. Take the experimental data as examples, extending the aging durability and dielectric strength of polymer dielectrics by 5 times and 16%, respectively, can have substantial commercial significance in energy storage, power electronics and power transmission areas. PMID:27338622

  8. Mesoporous Nano-Silica Serves as the Degradation Inhibitor in Polymer Dielectrics

    NASA Astrophysics Data System (ADS)

    Yang, Yang; Hu, Jun; He, Jinliang

    2016-06-01

    A new generation of nano-additives for robust high performance nanodielectrics is proposed. It is demonstrated for the first time that mesoporous material could act as “degradation inhibitor” for polymer dielectrics to sequestrate the electrical degradation products then restrain the electrical aging process especially under high temperature conditions, which is superior to the existing additives of nanodielectrics except further increasing the dielectric strength. Polyethylenimine (PEI) loaded nano-scaled mesoporous silica MCM-41 (nano-MS) is doped into the dielectric matrix to prepare the PP/MCM-41-PEI nanocomposites. PEI provides the amines to capture the electrical degradation products while the MCM-41 brackets afford large adsorption surface, bring down the activating temperature of the absorbent then enhance the absorptive capacity. The electrical aging tests confirm the contribution of the mesoporous structure to electrical aging resistance and FT-IR analysis of the electrical degraded regions demonstrates the chemical absorption especially under high temperature conditions. Take the experimental data as examples, extending the aging durability and dielectric strength of polymer dielectrics by 5 times and 16%, respectively, can have substantial commercial significance in energy storage, power electronics and power transmission areas.

  9. Mesoporous Nano-Silica Serves as the Degradation Inhibitor in Polymer Dielectrics

    PubMed Central

    Yang, Yang; Hu, Jun; He, Jinliang

    2016-01-01

    A new generation of nano-additives for robust high performance nanodielectrics is proposed. It is demonstrated for the first time that mesoporous material could act as “degradation inhibitor” for polymer dielectrics to sequestrate the electrical degradation products then restrain the electrical aging process especially under high temperature conditions, which is superior to the existing additives of nanodielectrics except further increasing the dielectric strength. Polyethylenimine (PEI) loaded nano-scaled mesoporous silica MCM-41 (nano-MS) is doped into the dielectric matrix to prepare the PP/MCM-41-PEI nanocomposites. PEI provides the amines to capture the electrical degradation products while the MCM-41 brackets afford large adsorption surface, bring down the activating temperature of the absorbent then enhance the absorptive capacity. The electrical aging tests confirm the contribution of the mesoporous structure to electrical aging resistance and FT-IR analysis of the electrical degraded regions demonstrates the chemical absorption especially under high temperature conditions. Take the experimental data as examples, extending the aging durability and dielectric strength of polymer dielectrics by 5 times and 16%, respectively, can have substantial commercial significance in energy storage, power electronics and power transmission areas. PMID:27338622

  10. Morphology and Optical Properties of Bare and Silica Coated Hybrid Silver Nanoparticles.

    PubMed

    Ghimire, Sushant; Lebek, Werner; Godehardt, Reinhold; Lee, Wan In; Adhikari, Rameshwar

    2016-05-01

    Owing to their wide applications in the field of optoelectronics, photonics, catalysis, and medicine; plasmonic metal nanoparticles are attaining considerable interest nowadays. The optical properties of these metal nanoparticles depend upon their size, shape, and surrounding medium. The present work studies the morphology and optical properties of bare silver nanoparticles and silica coated hybrid silver nanoparticles. Aqueous phase mediated synthesis and water-in-oil microemulsion mediated synthesis are two different wet chemical routes employed for nanosynthesis. Direct coating of silica is performed in water-in-oil microemulsion on pre-synthesized silver nanoparticles using tetraethyl orthosilicate as silica precursor. This study shows that using different wet chemical routes the size of the synthesized nanoparticles could be tuned. In addition, using reverse micelles as nanoreactors, the thickness of the silica shell around the core silver nanoparticles could be significantly controlled. Further, the optical properties of silver nanoparticles could be adjusted through the size and the surface coating. PMID:27483900

  11. Ultrasound assisted morphological control of mesoporous silica with improved lysozyme adsorption.

    PubMed

    Sun, Shumin; Wang, Shen; Wang, Peiyuan; Wu, Qiong; Fang, Shaoming

    2015-03-01

    The morphological control of mesoporous silica without any additives has attracted much attention. Discrete rod-like and string-of-beads like mesoporous SBA-15 can be achieved under ultrasound irradiation without changing the composition of synthesis system. The smaller particles of SBA-15 showed improved lysozyme immobilization capacity and higher adsorption rate over conventional rope-like SBA-15. PMID:25150609

  12. Morphology And Microstructure in Fused Silica Induced By High Fluence Ultraviolet 3omega (355 Nm) Laser Pulses

    SciTech Connect

    Wong, J.; Ferriera, J.L.; Lindsey, E.F.; Haupt, D.L.; Hutcheon, I.D.; Kinney, J.H.

    2007-08-08

    The morphology and microstructure induced in high quality fused silica by UV (355 nm) laser pulses at high fluence (10-45 J/cm{sup 2}) have been investigated using a suite of microscopic and spectroscopic tools. The laser beam has a near-Gaussian profile with a 1/e{sup 2} diameter of 0.98 mm at the sample plane and a pulse length FWHM (full width at half maximum) of 7.5 ns. The damage craters consist of a molten core region (thermal explosion), surrounded by a near concentric region of fractured material. The latter arises from propagation of lateral cracks induced by the laser-generated shock waves, which also compact the crater wall, {approx} 10 {micro}m thick and {approx} 20% higher in density. The size of the damage crater varies with laser fluence, number of pulses, and laser irradiation history. In the compaction layer, there is no detectable change in the Si/O stoichiometry to within {+-} 1.6% and no crystalline nano-particles of Si were observed. Micro- (1-10 {micro}m) and nano- (20-200 nm) cracks are found, however. A lower valence Si{sup 3+} species on the top 2-3 nm of the compaction layer is evident from the Si 2p XPS. The results are used to construct a physical model of the damage crater and to gain critical insight into laser damage process.

  13. Preparation of superhydrophobic and transparent micro-nano hybrid coatings from polymethylhydroxysiloxane and silica ormosil aerogels

    NASA Astrophysics Data System (ADS)

    Nagappan, Saravanan; Park, Jin Joo; Park, Sung Soo; Ha, Chang-Sik

    2014-12-01

    Superhydrophobic and transparent polymethylhydroxysiloxane (PMHOS)/silica ormosil aerogel hybrids were prepared successfully by mixing of PMHOS with various weight percentages of silica ormosil aerogels (as synthesized from methyltriethoxysilane (MTES) and methyltrimethoxysilane (MTMS) precursors) in separate seal perfume glass vials. The hybrids were spin coated on glass substrate at 1000 rpm for 60 seconds and used for further analysis. The surface morphology and chemical compositions of the hybrids were analyzed by high resolution scanning electron microscopy, high resolution transmission electron microscopy, atomic force spectroscopy, adsorption and desorption isotherm, and X-ray photoelectron spectroscopy. The transparency, thermal decomposition and static contact angle (SCA) of each sample were measured by UV-Visible spectrophotometer, TGA and drop shape analysis system, respectively. The spin coated substrates showed good superhydrophobic properties, thermal stability as well as transparency on the glass substrates.

  14. Amorphous Silica- and Carbon- rich nano-templated surfaces as model interstellar dust surfaces for laboratory astrochemistry

    NASA Astrophysics Data System (ADS)

    Pascual, Natalia; Dawes, Anita; González-Posada, Fernando; Thompson, Neil; Chakarov, Dinko; Mason, Nigel J.; Fraser, Helen Jane

    2015-08-01

    Experimental studies on surface astrochemistry are vital to our understanding of chemical evolution in the interstellar medium (ISM). Laboratory surface-astrochemists have recently begun to study chemical reactions on interstellar dust-grain mimics, ranging from graphite, HOPG and graphene (representative of PAHs or large C-grains in the ISM) to amorphous olivine (representative of silicate dust) and ablated meteoritic samples (representative of interplanetary dust). These pioneering experiments show that the nature of the surface fundamentally affects processes at the substrate surface, substrate-ice interface, and ice over-layer. What these experiments are still lacking is the ability to account for effects arising from the discrete nano-scale of ISM grains, which might include changes to electronic structure, optical properties and surface-kinetics in comparison to bulk materials. The question arises: to what extent are the chemical and optical properties of interstellar ices affected by the size, morphology and material of the underlying ISM dust?We have designed, fabricated and characterised a set of nano-structured surfaces, where nanoparticles, representative of ISM grains, are adhered to an underlying support substrate. Here we will show the nanoparticles that have been manufactured from fused-silica (FS), glassy carbon (GC) and amorphous-C (aC). Our optical characterisation data shows that the nanostructured surfaces have different absorption cross-sections and significant scattering in comparison to the support substrates, which has implications for the energetic processing of icy ISM dust. We have been able to study how water-ice growth differs on the nanoparticles in comparison to the “flat” substrates, indicating increased ice amorphicity when nanoparticles are present, and on C-rich surfaces, compared to Si-rich particles. These data will be discussed in the context of interstellar water-ice features.

  15. Mixed surfactants-directed the mesoporous silica materials with various morphologies and structures

    SciTech Connect

    Lin Huiming; Qu Fengyu; Wu Xiang; Xue Ming; Zhu Guangshan; Qiu Shilun

    2011-06-15

    A new mixed surfactants system using alkyl carboxylic acids and quaternized poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl] urea] (PEPU) as the co-template was used to synthesize mesoporous silica materials with various morphologies and structures, including flakes, regular spheres, nanoparticles, and tube-spheres. The cationic polymer connected the anionic surfactant micelle to the anionic polysilicate species to induce the synthesis of the mesoporous silica materials. The structure and property of the surfactant and the cationic polymer determined the formation of mesoporous silica, and also had a signification influence on the morphology and structure of the final materials. To further explore the possible formation mechanism of these mesoporous materials, zeta potential was utilized to evaluate the interaction between the anionic surfactant and the cationic co-template. In addition, the structure, morphology, and porosity of these materials were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N{sub 2} adsorption-desorption measurements. - Graphical abstract: A new mixed surfactants system using alkyl carboxylic acids and PEPU as the co-template was used to synthesize mesoporous silica materials with various morphologies and structures. Highlights: {yields}A new mixed surfactants system induced the mesoporous silica materials with various morphologies and structure. > It is a development of the type S{sup -}N{sup +}I{sup -} route of the mesoporous formation. > Zeta potential was utilized to evaluate the interaction between the anionic surfactant and the cationic co-template. > The property and amount of surfactant and polymer determined the formation of the mesoporous materials.

  16. Morphology controlling method for amorphous silica nanoparticles and jellyfish-like nanowires and their luminescence properties

    NASA Astrophysics Data System (ADS)

    Liu, Haitao; Huang, Zhaohui; Huang, Juntong; Xu, Song; Fang, Minghao; Liu, Yan-Gai; Wu, Xiaowen; Zhang, Shaowei

    2016-03-01

    Uniform silica nanoparticles and jellyfish-like nanowires were synthesized by a chemical vapour deposition method on Si substrates treated without and with Ni(NO3)2, using silicon powder as the source material. Composition and structural characterization using field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fourier-transform infrared spectroscopy showed that the as-prepared products were silica nanoparticles and nanowires which have amorphous structures. The form of nanoparticles should be related to gas-phase nucleation procedure. The growth of the nanowires was in accordance with vapour-liquid-solid mechanism, followed by Ostwald ripening to form the jellyfish-like morphology. Photoluminescence and cathodoluminescence measurements showed that the silica products excited by different light sources show different luminescence properties. The emission spectra of both silica nanoparticles and nanowires are due to the neutral oxygen vacancies (≡Si-Si≡). The as-synthesized silica with controlled morphology can find potential applications in future nanodevices with tailorable photoelectric properties.

  17. Morphology controlling method for amorphous silica nanoparticles and jellyfish-like nanowires and their luminescence properties.

    PubMed

    Liu, Haitao; Huang, Zhaohui; Huang, Juntong; Xu, Song; Fang, Minghao; Liu, Yan-Gai; Wu, Xiaowen; Zhang, Shaowei

    2016-01-01

    Uniform silica nanoparticles and jellyfish-like nanowires were synthesized by a chemical vapour deposition method on Si substrates treated without and with Ni(NO3)2, using silicon powder as the source material. Composition and structural characterization using field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fourier-transform infrared spectroscopy showed that the as-prepared products were silica nanoparticles and nanowires which have amorphous structures. The form of nanoparticles should be related to gas-phase nucleation procedure. The growth of the nanowires was in accordance with vapour-liquid-solid mechanism, followed by Ostwald ripening to form the jellyfish-like morphology. Photoluminescence and cathodoluminescence measurements showed that the silica products excited by different light sources show different luminescence properties. The emission spectra of both silica nanoparticles and nanowires are due to the neutral oxygen vacancies (≡Si-Si≡). The as-synthesized silica with controlled morphology can find potential applications in future nanodevices with tailorable photoelectric properties. PMID:26940294

  18. Morphology controlling method for amorphous silica nanoparticles and jellyfish-like nanowires and their luminescence properties

    PubMed Central

    Liu, Haitao; Huang, Zhaohui; Huang, Juntong; Xu, Song; Fang, Minghao; Liu, Yan-gai; Wu, Xiaowen; Zhang, Shaowei

    2016-01-01

    Uniform silica nanoparticles and jellyfish-like nanowires were synthesized by a chemical vapour deposition method on Si substrates treated without and with Ni(NO3)2, using silicon powder as the source material. Composition and structural characterization using field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fourier-transform infrared spectroscopy showed that the as-prepared products were silica nanoparticles and nanowires which have amorphous structures. The form of nanoparticles should be related to gas-phase nucleation procedure. The growth of the nanowires was in accordance with vapour-liquid-solid mechanism, followed by Ostwald ripening to form the jellyfish-like morphology. Photoluminescence and cathodoluminescence measurements showed that the silica products excited by different light sources show different luminescence properties. The emission spectra of both silica nanoparticles and nanowires are due to the neutral oxygen vacancies (≡Si-Si≡). The as-synthesized silica with controlled morphology can find potential applications in future nanodevices with tailorable photoelectric properties. PMID:26940294

  19. Concentration gradient induced morphology evolution of silica nanostructure growth on photoresist-derived carbon micropatterns

    PubMed Central

    2012-01-01

    The evolution of silica nanostructure morphology induced by local Si vapor source concentration gradient has been investigated by a smart design of experiments. Silica nanostructure or their assemblies with different morphologies are obtained on photoresist-derived three-dimensional carbon microelectrode array. At a temperature of 1,000°C, rope-, feather-, and octopus-like nanowire assemblies can be obtained along with the Si vapor source concentration gradient flow. While at 950°C, stringlike assemblies, bamboo-like nanostructures with large joints, and hollow structures with smaller sizes can be obtained along with the Si vapor source concentration gradient flow. Both vapor–liquid-solid and vapor-quasiliquid-solid growth mechanisms have been applied to explain the diverse morphologies involving branching, connecting, and batch growth behaviors. The present approach offers a potential method for precise design and controlled synthesis of nanostructures with different features. PMID:22938090

  20. Concentration gradient induced morphology evolution of silica nanostructure growth on photoresist-derived carbon micropatterns

    NASA Astrophysics Data System (ADS)

    Liu, Dan; Shi, Tielin; Xi, Shuang; Lai, Wuxing; Liu, Shiyuan; Li, Xiaoping; Tang, Zirong

    2012-09-01

    The evolution of silica nanostructure morphology induced by local Si vapor source concentration gradient has been investigated by a smart design of experiments. Silica nanostructure or their assemblies with different morphologies are obtained on photoresist-derived three-dimensional carbon microelectrode array. At a temperature of 1,000°C, rope-, feather-, and octopus-like nanowire assemblies can be obtained along with the Si vapor source concentration gradient flow. While at 950°C, stringlike assemblies, bamboo-like nanostructures with large joints, and hollow structures with smaller sizes can be obtained along with the Si vapor source concentration gradient flow. Both vapor-liquid-solid and vapor-quasiliquid-solid growth mechanisms have been applied to explain the diverse morphologies involving branching, connecting, and batch growth behaviors. The present approach offers a potential method for precise design and controlled synthesis of nanostructures with different features.

  1. Further Insight into the Definite Morphology and Formation Mechanism of Mesoporous Silica KCC-1.

    PubMed

    Febriyanti, E; Suendo, V; Mukti, R R; Prasetyo, A; Arifin, A F; Akbar, M A; Triwahyono, S; Marsih, I N; Ismunandar

    2016-06-14

    The unique three-dimensional pore structure of KCC-1 has attracted significant attention and has proven to be different compared to other conventional mesoporous silica such as the MCM-41 family, SBA-15, or even MSN nanoparticles. In this research, we carefully examine the morphology of KCC-1 to define more appropriate nomenclature. We also propose a formation mechanism of KCC-1 based on our experimental evidence. Herein, the KCC-1 morphology was interpreted mainly on the basis of compiling all observation and information taken from SEM and TEM images. Further analysis on TEM images was carried out. The gray value intensity profile was derived from TEM images in order to determine the specific pattern of this unique morphology that is found to be clearly different from that of other types of porous spherical-like morphologies. On the basis of these results, the KCC-1 morphology would be more appropriately reclassified as bicontinuous concentric lamellar morphology. Some physical characteristics such as the origin of emulsion, electrical conductivity, and the local structure of water molecules in the KCC-1 emulsion were disclosed to reveal the formation mechanism of KCC-1. The origin of the KCC-1 emulsion was characterized by the observation of the Tyndall effect, conductometry to determine the critical micelle concentration, and Raman spectroscopy. In addition, the morphological evolution study during KCC-1 synthesis completes the portrait of the formation of mesoporous silica KCC-1. PMID:27120557

  2. Biodegradation of 2,4-dinitrophenol with laccase immobilized on nano-porous silica beads

    PubMed Central

    2013-01-01

    Many organic hazardous pollutants, including 2,4-dinitrophenol (2,4-DNP), which are water soluble, toxic, and not easily biodegradable make concerns for environmental pollution worldwide. In the present study, degradation of nitrophenols-contained effluents by using laccase immobilized on the nano-porous silica beads was evaluated. 2,4-DNP was selected as the main constituent of industrial effluents containing nitrophenols. The performance of the system was characterized as a function of pH, contact time, temperature, pollutant, and mediator concentrations. The laccase-silica beads were employed in a mixed-batch reactor to determine the degradation efficiency after 12 h of enzyme treatment. The obtained data showed that the immobilized laccase degraded more than 90% of 2,4-DNP within 12 h treatment. The immobilization process improved the activity and sustainability of laccase for degradation of the pollutant. Temperatures more than 50°C reduced the enzyme activity to about 60%. However, pH and the mediator concentration could not affect the enzyme activity. The degradation kinetic was in accordance with a Michaelis–Menten equation with Vmax and Km obtained as 0.25–0.38 μmoles/min and 0.13–0.017 mM, respectively. The stability of the immobilized enzyme was maintained for more than 85% of its initial activity after 30 days. Based on the results, it can be concluded that high resistibility and reusability of immobilized laccase on CPC-silica beads make it considerable choice for wastewater treatment. PMID:23547870

  3. Dehydration of Glycerin to Acrolein Over Heteropolyacid Nano-Catalysts Supported on Silica-Alumina.

    PubMed

    Kang, Tae Hun; Choi, Jung Ho; Choi, Jun Seon; Song, In Kyu

    2015-10-01

    A series of H3PW12O40 nano-catalysts supported on silica-alumina (XH3PW12O40/SA (X = 10, 15, 20, 25, and 30)) with different H3PW12O40 content (X, wt%) were prepared, and they were applied to the dehydration of glycerin to acrolein. The effect of H3PW12O40 content on the physicochemical properties and catalytic activities of XH3PW12O40/SA nano-catalysts was investigated. Surface area and pore volume of XH3PW12O40/SA catalysts decreased with increasing H3PW12O40 content. Formation of H3PW12O40 aggregates was observed in the catalysts with high H3PW12O40 loading. Brønsted acidity of the catalysts showed a volcano-shaped trend with respect to H3PW12O40 content. It was revealed that yield for acrolein increased with increasing Brønsted acidity of XH3PW12O40/SA catalysts. Brønsted acidity of XH3PW12O40/SA catalysts served as a crucial factor determining the catalytic performance in the dehydration of glycerin. Among the catalysts tested, 25H3PW12O40/SA catalyst with the largest Brønsted acidity showed the best catalytic performance. PMID:26726511

  4. Development of mechano-responsive polymeric scaffolds using functionalized silica nano-fillers for the control of cellular functions.

    PubMed

    Griffin, Michelle; Nayyer, Leila; Butler, Peter E; Palgrave, Robert G; Seifalian, Alexander M; Kalaskar, Deepak M

    2016-08-01

    We demonstrate an efficient method to produce mechano-responsive polymeric scaffolds which can alter cellular functions using two different functionalized (OH and NH2) silica nano-fillers. Fumed silica-hydroxyl and fumed silica-amine nano-fillers were mixed with a biocompatible polymer (POSS-PCU) at various wt% to produce scaffolds. XPS and mechanical testing demonstrate that bulk mechanical properties are modified without changing the scaffold's surface chemistry. Mechanical testing showed significant change in bulk properties of POSS-PCU scaffolds with an addition of silica nanofillers as low as 1% (P<0.01). Scaffolds modified with NH2 silica showed significantly higher bulk mechanical properties compared to the one modified with the OH group. Enhanced cell adhesion, proliferation and collagen production over 14days were observed on scaffolds with higher bulk mechanical properties (NH2) compared to those with lower ones (unmodified and OH modified) (P<0.05) during in vitro analysis. This study provides an effective method of manufacturing mechano-responsive polymeric scaffolds, which can help to customize cellular responses for biomaterial applications. PMID:27013128

  5. Comparison of Nanoparticle Exposures Between Fumed and Sol-gel Nano-silica Manufacturing Facilities

    PubMed Central

    OH, Sewan; KIM, Boowook; KIM, Hyunwook

    2014-01-01

    Silica nanoparticles (SNPs) are widely used all around the world and it is necessary to evaluate appropriate risk management measures. An initial step in this process is to assess worker exposures in their current situation. The objective of this study was to compare concentrations and morphologic characteristics of fumed (FS) and sol-gel silica nanoparticles (SS) in two manufacturing facilities. The number concentration (NC) and particle size were measured by a real-time instrument. Airborne nanoparticles were subsequently analyzed using a TEM/EDS. SNPs were discharged into the air only during the packing process, which was the last manufacturing step in both the manufacturing facilities studied. In the FS packing process, the geometric mean (GM) NC in the personal samples was 57,000 particles/cm3. The geometric mean diameter (GMD) measured by the SMPS was 64 nm. Due to the high-temperature formation process, the particles exhibited a sintering coagulation. In the SS packing process that includes a manual jet mill operation, the GM NC was calculated to be 72,000 particles/cm3 with an assumption of 1,000,000 particles/cm3 when the upper limit is exceeded (5% of total measure). The particles from SS process had a spherical-shaped morphology with GMD measured by SMPS of 94 nm. PMID:24583511

  6. Additive-induced morphological tuning of self-assembled silica-barium carbonate crystal aggregates

    NASA Astrophysics Data System (ADS)

    Kellermeier, Matthias; Glaab, Fabian; Carnerup, Anna M.; Drechsler, Markus; Gossler, Benjamin; Hyde, Stephen T.; Kunz, Werner

    2009-04-01

    Crystallisation of barium carbonate from alkaline silica solutions results in the formation of extraordinary micron-scale architectures exhibiting non-crystallographic curved shapes, such as helical filaments and worm-like braids. These so-called "silica biomorphs" consist of a textured assembly of uniform elongated witherite nanocrystallites, which is occasionally sheathed by a skin of amorphous silica. Although great efforts have been devoted to clarifying the physical origin of these fascinating materials, to date little is known about the processes underlying the observed self-organisation. Herein, we describe the effect of two selected additives, a cationic surfactant and a cationic polymer, on the morphology of the forming crystal aggregates, and relate changes to experiments conducted in the absence of additives. Minor amounts of both substances are shown to exert a significant influence on the growth process, leading to the formation of predominantly flower-like spherulitic aggregates. The observed effects are discussed in terms of feasible morphogenesis pathways. Based on the assumption of a template membrane steering biomorph formation, it is proposed that the two additives are capable of performing specific bridging functions promoting the aggregation of colloidal silica which constitutes the membrane. Morphological changes are tentatively ascribed to varying colloid coordination effecting distinct membrane curvatures.

  7. Structure and morphology evolution of silica-modified pseudoboehmite aerogels during heat treatment

    NASA Astrophysics Data System (ADS)

    Pakharukova, V. P.; Shalygin, A. S.; Gerasimov, E. Yu.; Tsybulya, S. V.; Martyanov, O. N.

    2016-01-01

    Silica-modified pseudoboehmite aerogels (0, 10, 20 at% of Si) were prepared by sol-gel method followed by supercritical drying. The phase transformations, changes in structure and morphology upon calcination were thoroughly investigated by advanced X-Ray diffraction (XRD) techniques and high-resolution transmission electron microscopy (HRTEM). Obtained pseudoboehmite samples had specific nanostructure: ultrathin two-dimensional (2D) crystallites were loosely packed. The silica dopant drastically enhanced the crystallite anisotropy. Thus, the aerogel with Al:Si atomic ratio of 9:1 consisted of the pseudoboehmite nanosheets with thickness of one unit cell (average dimensions of 14.0×1.2×14.5 nm). The specific nanostructure caused remarkable features of experimental XRD patterns, including anisotropic peak broadening and appearance of forbidden reflection. Direct simulation of XRD patterns with using the Debye Scattering Equation allowed the size and morphology of pseudoboehmite crystallites to be determined. The silica addition strongly delayed formation of γ-alumina and further phase transformations upon calcinaton. Thermal stability of alumina was suggested to be affected by the particle morphology inherited from the pseudoboehmite precursor.

  8. Mixed surfactants-directed the mesoporous silica materials with various morphologies and structures

    NASA Astrophysics Data System (ADS)

    Lin, Huiming; Qu, Fengyu; Wu, Xiang; Xue, Ming; Zhu, Guangshan; Qiu, Shilun

    2011-06-01

    A new mixed surfactants system using alkyl carboxylic acids and quaternized poly[bis(2-chloroethyl)ether-alt-1,3-bis[3-(dimethylamino)propyl] urea] (PEPU) as the co-template was used to synthesize mesoporous silica materials with various morphologies and structures, including flakes, regular spheres, nanoparticles, and tube-spheres. The cationic polymer connected the anionic surfactant micelle to the anionic polysilicate species to induce the synthesis of the mesoporous silica materials. The structure and property of the surfactant and the cationic polymer determined the formation of mesoporous silica, and also had a signification influence on the morphology and structure of the final materials. To further explore the possible formation mechanism of these mesoporous materials, zeta potential was utilized to evaluate the interaction between the anionic surfactant and the cationic co-template. In addition, the structure, morphology, and porosity of these materials were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N 2 adsorption-desorption measurements.

  9. Effect of polyvinylpyrrolidone on mesoporous silica morphology and esterification of lauric acid with 1-butanol catalyzed by immobilized enzyme

    SciTech Connect

    Zhang, Jinyu; Zhou, Guowei Jiang, Bin; Zhao, Minnan; Zhang, Yan

    2014-05-01

    Mesoporous silica materials with a range of morphology evolution, i.e., from curved rod-shaped mesoporous silica to straight rod-shaped mesoporous silica, were successfully prepared using polyvinylpyrrolidone (PVP) and triblock copolymer as dual template. The effects of PVP molecular weight and concentration on mesoporous silica structure parameters were studied. Results showed that surface area and pore volume continuously decreased with increased PVP molecular weight. Mesoporous silica prepared with PVP K30 also possessed larger pore diameter, interplanar spacing (d{sub 100}), and cell parameter (a{sub 0}) than that prepared with PVP K15 and PVP K90. In addition, with increased PVP concentration, d{sub 100} and a{sub 0} continuously decreased. The mechanism of morphology evolution caused by the change in PVP concentration was investigated. The conversion rate of lauric acid with 1-butanol catalyzed by immobilized Porcine pancreatic lipase (PPL) was also evaluated. Results showed that PPL immobilized on amino-functionalized straight rod-shaped mesoporous silica maintained 50% of its esterification conversion rate even after five cycles of use with a maximum conversion rate was about 90.15%. - Graphical abstract: Curved rod-shaped mesoporous silica can be obtained at low and the highest PVP concentration, while straight rod-shaped mesoporous silica can be obtained at higher PVP concentration. - Highlights: • Mesoporous silica with morphology evolution from CRMS to SRMS were prepared. • Effects of PVP molecular weight and concentration on silica morphology were studied. • A possible mechanism for the formation of morphology evolution SiO{sub 2} was proposed. • Esterification of lauric acid with 1-butanol catalyzed by immobilized PPL.

  10. Correlation between interfacial interactions and mechanical properties of PA-6 doped with surface-capped nano-silica

    NASA Astrophysics Data System (ADS)

    Li, Deliang; Liu, Qing; Yu, Laigui; Li, Xiaohong; Zhang, Zhijun

    2009-06-01

    The polyamide-6 pellets were mixed with nano-SiO 2 particles surface-capped by 3-aminopropyltriethoxysilane (APS) via a melt blending route. PA-6 composites doped with surface-capped nano-SiO 2 (designated as PAMNS, where AMNS refers to APS surface-capped nano-SiO 2). AMNS and the silica samples (designated as EAMNS) extracted by acid etching from various PAMNS samples containing different concentration of amino functional groups on surface-capped nano-silica surfaces were characterized by means of Fourier transformation infrared spectrometry (FTIR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA). This aims at revealing the interfacial interaction between AMNS and PA-6 matrix and its effect on the mechanical properties of the filled PA-6 composites. The chemical features and microstructures of the PAMNS composites were analyzed by means of FTIR and transmission electron microscopy (TEM), respectively, while their mechanical properties were evaluated using standardized test rigs. Results demonstrate that the surface-modified nano-SiO 2 particles were uniformly dispersed in PA-6 matrix. The residue silica extracted from various PAMNS samples showed characteristic FTIR absorbance peak of PA-6 and had larger weight losses than AMNS, implying that the polymeric matrix was chemically bonded with the nanofiller particles. The interfacial interactions are closely related to the concentration of functional groups in AMNS, and there might exist a critical concentration at which the strongest interfacial interactions could be reached. Beyond the critical concentration of the functional groups in AMNS, the mechanical properties of the filled PA-6 composites tended to decrease to some extent.

  11. Reducing Logistics Footprints and Replenishment Demands: Nano-engineered Silica Aerogels a Proven Method for Water Treatment

    SciTech Connect

    Daily, W; Coleman, S; Love, A; Reynolds, J; O'Brien, K; Gammon, S

    2004-09-22

    Rapid deployment and the use of objective force aggressively reduce logistic footprints and replenishment demands. Maneuver Sustainment requires that Future Combat Systems be equipped with water systems that are lightweight, have small footprints, and are highly adaptable to a variety of environments. Technologies employed in these settings must be able to meet these demands. Lawrence Livermore National Laboratory has designed and previously field tested nano-engineered materials for the treatment of water. These materials have been either based on silica aerogel materials or consist of composites of these aerogels with granular activated carbon (GAC). Recent tests have proven successful for the removal of contaminants including uranium, hexavalent chromium, and arsenic. Silica aerogels were evaluated for their ability to purify water that had been spiked with the nerve agent VX (O-ethyl S-(2-diisopropylaminoethyl) methylphosphonothiolate). These results demonstrated that silica aerogels were able to remove the VX from the supply water and were nearly 30 times more adsorbent than GAC. This performance could result in REDUCING CHANGEOUT FREQUENCY BY A FACTOR OF 30 or DECREASING the VOLUME of adsorbent BY A FACTOR OF 30; thereby significantly reducing logistic footprints and replenishment demands. The use of the nano-engineered Silica Aerogel/GAC composites would provide a water purification technology that meets the needs of Future Combat Systems.

  12. Linking CO2 Sorption Performance to Polymer Morphology in Aminopolymer/Silica Composites through Neutron Scattering.

    PubMed

    Holewinski, Adam; Sakwa-Novak, Miles A; Jones, Christopher W

    2015-09-16

    Composites of poly(ethylenimine) (PEI) and mesoporous silica are effective, reversible adsorbents for CO2, both from flue gas and in direct air-capture applications. The morphology of the PEI within the silica can strongly impact the overall carbon capture efficiency and rate of saturation. Here, we directly probe the spatial distribution of the supported polymer through small-angle neutron scattering (SANS). Combined with textural characterization from physisorption analysis, the data indicate that PEI first forms a thin conformal coating on the pore walls, but all additional polymer aggregates into plug(s) that grow along the pore axis. This model is consistent with observed trends in amine-efficiency (CO2/N binding ratio) and pore size distributions, and points to a trade-off between achieving high chemical accessibility of the amine binding sites, which are inaccessible when they strongly interact with the silica, and high accessibility for mass transport, which can be hampered by diffusion through PEI plugs. We illustrate this design principle by demonstrating higher CO2 capacity and uptake rate for PEI supported in a hydrophobically modified silica, which exhibits repulsive interactions with the PEI, freeing up binding sites. PMID:26308183

  13. Morphology evolution of fused silica surface during ion beam figuring of high-slope optical components.

    PubMed

    Liao, Wenlin; Dai, Yifan; Xie, Xuhui; Zhou, Lin

    2013-06-01

    Ultra-precision and ultra-smooth surfaces are vitally important for some high performance optical systems. Ion beam figuring (IBF) is a well-established, highly deterministic method for the final precision figuring of extremely high quality optical surfaces, whereas ion sputtering induced smoothing, or roughening for nanoscale surface morphology, strongly depends on the processing conditions. Usually, an improper machining method would arouse the production of nanoscale patterns leading to the coarsening of the optical surface. In this paper, the morphology evolution mechanism on a fused silica surface during IBF of high-slope optical components has been investigated by means of atomic force microscopy. Figuring experiments are implemented on two convex spherical surfaces by using different IBF methods. Both of their surface errors are rapidly reduced to 1.2 nm root mean square (RMS) after removing similar deep material, but their surfaces are characterized with obviously different nanoscale morphologies. The experimental results indicate that the ion incidence angle dominates the microscopic morphology during the IBF process. At near-normal incidence, fused silica achieves an ultra-smooth surface with an RMS roughness value R(q) down to 0.1 nm, whereas nanoscale ripple patterns are observed at a large incidence angle with an R(q) value increasing to more than 0.9 nm. Additionally, the difference of incidence angles on various machined areas would influence the uniformity of surface quality, resulting from the interplay between the smoothing and roughening effects induced by ion sputtering. PMID:23736325

  14. Morphology and structure of particles produced by femtosecond laser ablation of fused silica

    NASA Astrophysics Data System (ADS)

    Sharma, S. P.; Oliveira, V.; Vilar, Rui

    2016-04-01

    The aim of the present work was to study the morphology and structure of the nanoparticles produced by femtosecond laser ablation of fused silica. Ultrashort laser pulses of 1030 nm wavelength and 550 fs duration were tightly focused by a high numerical aperture microscope objective at the surface of fused silica samples while scanning the sample in relation to the stationary laser beam. Laser tracks were created with pulse energies in the range 5-100 μJ, resulting in ablation debris of different morphologies. The debris were examined by scanning and transmission electron microscopy for their morphology and crystal structure in relation to the incident laser pulse energy. Ejected particles with sizes ranging from a few nanometers to a few microns were found. Their morphologies can be broadly classified into three categories: very fine round nanoparticles with diameters lower than 20 nm, nanoparticles with intermediate sizes between 50 and 200 nm, and big irregular particles with typical size between 0.5 and 1.5 μm. The fine nanoparticles of the first category are predominantly observed at higher pulse energies and tend to aggregate to form web-like and arborescent-like structures. The nanoparticles with intermediate sizes are observed for all pulse energies used and may appear isolated or aggregated in clusters. Finally, the larger irregular particles of the third category are observed for all energies and appear normally isolated.

  15. Resolving the morphology of niobium carbonitride nano-precipitates in steel using atom probe tomography.

    PubMed

    Breen, Andrew J; Xie, Kelvin Y; Moody, Michael P; Gault, Baptiste; Yen, Hung-Wei; Wong, Christopher C; Cairney, Julie M; Ringer, Simon P

    2014-08-01

    Atom probe is a powerful technique for studying the composition of nano-precipitates, but their morphology within the reconstructed data is distorted due to the so-called local magnification effect. A new technique has been developed to mitigate this limitation by characterizing the distribution of the surrounding matrix atoms, rather than those contained within the nano-precipitates themselves. A comprehensive chemical analysis enables further information on size and chemistry to be obtained. The method enables new insight into the morphology and chemistry of niobium carbonitride nano-precipitates within ferrite for a series of Nb-microalloyed ultra-thin cast strip steels. The results are supported by complementary high-resolution transmission electron microscopy. PMID:25410602

  16. Incorporating Nano-silica as a Binder to Improve Corrosion Resistance of High Alumina Refractory Castables

    NASA Astrophysics Data System (ADS)

    Ramezani, Abbas; Mohebi, Mohammad Masoud; Souri, Alireza

    2013-04-01

    In this study, four types of castables as calcium-aluminate cement (CAC)-bonded and nano-silica (NS)-bonded castables based on tabular-alumina and bauxite aggregates were prepared to investigate the replacement of the calcium-aluminate cement by NS. All samples were allowed to dry at 110 °C then fired at 800 and 1200 °C. Bulk density and apparent porosity of samples were measured. The molten aluminum static corrosion test (cup test) results showed that NS-bonded specimens had higher resistance to corrosion compared to CAC-bonded samples (based on the measured average aluminum penetration depth into the refractory texture). However no penetration was observed in bauxite NS-bonded samples. The results were consistent with dynamic corrosion test in aluminum melt carried out at 800 °C for 100 h. The small pore size in NS-bonded castables was found to be the main cause for high corrosion resistance as micro-pores prevented the melt to penetrate into the refractory.

  17. Transport of nano zero-valent iron supported by mesoporous silica microspheres in porous media.

    PubMed

    Yang, Zhangmei; Qiu, Xinhong; Fang, Zhanqiang; Pokeung, Tsang

    2015-01-01

    Effective in situ remediation of groundwater requires the successful delivery of reactive iron particles through sand. However, the agglomeration of nano zero-valent iron (NZVI) particles limits the migration distance, which inhibits their usefulness. In the study described herein, NZVI supported by mesoporous silica microspheres covered with FeOOH (SiO2@FeOOH@Fe) was synthesized, and its mobility was demonstrated on the basis of transport in porous media. Degradation of decabromodiphenyl ether (BDE209) was more efficient by SiO2@FeOOH@Fe than by 'bare' NZVI. Breakthrough curves and mass recovery showed the mobility of SiO2@FeOOH@Fe in granular media was better than that of bare NZVI. It increased greatly in the presence of natural organic matter (NOM) and decreased when high Ca2+ and Mg2+ concentrations were encountered. Analysis of the transport data on the basis of filtration theory showed diffusion to be the main mechanism for particle removal in silicon sand. Increasing the NOM may decrease agglomeration of the grains of sand, which has a positive effect on the mobility of SiO2@FeOOH@Fe. Presumably, increasing the concentrations of Ca2+ and Mg2+ compresses the diffuse double layer of SiO2@FeOOH@Fe, resulting in a reduction of mobility. PMID:26067499

  18. Kinetically-controlled template-free synthesis of hollow silica micro-/nanostructures with unusual morphologies

    NASA Astrophysics Data System (ADS)

    Zhang, An-Qi; Li, Hui-Jun; Qian, Dong-Jin; Chen, Meng

    2014-04-01

    We report a kinetically-controlled template-free room-temperature production of hollow silica materials with various novel morphologies, including tubes, crutches, ribbons, bundles and bells. The obtained products, which grew in a well-controlled manner, were monodispersed in shape and size. The role of ammonia, sodium citrate, polyvinylpyrrolidone, chloroauric acid and NaCl in shape control is discussed in detail. The oriented growth of these micro-/nanostructures directed by reverse micelles followed a solution-solution-solid (SSS) mechanism, similar to the classic vapor-liquid-solid mechanism. The evolution processes of silica rods, tubes, crutches, bundles and bells were recorded using transmission electron microscopy to prove the SSS mechanism.

  19. Synthesis of silica supported titania nanocomposite in controllable phase content and morphology

    NASA Astrophysics Data System (ADS)

    Lim, Yew Von; Fan, Haiming; Shen, Zexiang; Kang, Chiang Huen; Feng, Yuanping; Wang, Shijie

    2009-05-01

    The silica supported titania nanocomposite thin films with controllable particle size and phase content were successfully prepared by a convenient post annealing approach involving in solid-solid interfacial reaction. The effects of growth conditions, such as the annealing temperature and silicon concentration on the particle size and phase content, were systematically studied by using Atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD), and X-ray spectroscopy (XPS). The results indicate that the silicon concentration is a dominant factor in the morphology, crystallization and phase transformation of these nanocomposites. A mechanism for the high temperature phase transformation is also proposed based on the migration of the oxygen vacancies.

  20. Structure and Morphology Study of Cobalt Oxide Doped Silica Nanocomposite Films

    NASA Astrophysics Data System (ADS)

    Drasovean, Romana; Monteiro, Regina; Cherif, Mourad

    2010-01-01

    Cobalt oxide doped silica films were synthesized by a dip-coating technique. Initial compounds were cobalt acetate Co(CH3COO)2ṡ4H2O and tetraethoxysilane Si(OC2H5)4. The chemical composition was studied by X-ray diffraction and UV-Vis spectroscopy. The morphology analyses were carried out by means of atomic force microscopy. The average diameter of cobalt oxide dispersed particles increases with the molar ratio Co:Si and with the aging time of the initial colloidal solution.

  1. Chromium doped nano-phase separated yttria-alumina-silica glass based optical fiber preform: fabrication and characterization

    NASA Astrophysics Data System (ADS)

    Dutta, Debjit; Dhar, Anirban; Das, Shyamal; Bysakh, Sandip; Kir'yanov, Alexandar; Paul, Mukul Chandra

    2015-06-01

    Transition metal (TM) doping in silica core optical fiber is one of the research area which has been studied for long time and Chromium (Cr) doping specially attracts a lot of research interest due to their broad emission band covering U, C and L band with many potential application such as saturable absorber or broadband amplifier etc. This paper present fabrication of Cr doped nano-phase separated silica fiber within yttria-alumina-silica core glass through conventional Modified Chemical Vapor Deposition (MCVD) process coupled with solution doping technique along with different material and optical characterization. For the first time scanning electron microscope (SEM) / energy dispersive X-ray (EDX) analysis of porous soot sample and final preform has been utilized to investigate incorporation mechanism of Crions with special emphasis on Cr-species evaporation at different stages of fabrication. We also report that optimized annealing condition of our fabricated preform exhibited enhanced fluorescence emission and a broad band within 550- 800 nm wavelength region under pumping at 532 nm wavelength due to nano-phase restructuration.

  2. Thermal decomposition behaviors and kinetic properties of 1,8-naphthalic anhydride loaded dense nano-silica hybrids

    NASA Astrophysics Data System (ADS)

    Wang, Jinpeng; Sun, Jihong; Wang, Feng; Ren, Bo

    2013-06-01

    A certain amount of (3-aminopropyl)triethoxysilane (APTES) and various capacity of 1,8-naphthalic anhydride (NA) were employed to modify and then graft onto the surface of the dense nano-silica spheres (DNSS) via a post-grafting method, and thereby, a novel luminescent density nano-silica hybrid materials have been successfully synthesized. Meanwhile, the structures and properties of obtained hybrid DNSS were characterized by XRD, TEM, N2 sorption, FT-IR, and TG analysis. Furthermore, the thermal stability of before and after modification were demonstrated by using both Kissinger methods and Ozawa-Flynn-Wall methods. Particularly, the thermal decomposition behaviors of amino-modified groups and NA-grafted organic molecules were emphasized based on the TG and DTG analysis and then the related mechanism was put forward according to Coats and Redfern methods. Finally, as a comparison, the obtained results and the proposed decomposition mechanism of hybrid DNSS with non-pores were discussed with that of mesopores silicas in details.

  3. In vitro comet and micronucleus assays do not predict morphological transforming effects of silica particles in Syrian Hamster Embryo cells.

    PubMed

    Darne, Christian; Coulais, Catherine; Terzetti, Francine; Fontana, Caroline; Binet, Stéphane; Gaté, Laurent; Guichard, Yves

    2016-01-15

    Crystalline silica particles and asbestos have both been classified as carcinogenic by the International Agency for Research on Cancer (IARC). However, because of the limited data available, amorphous silica was not classifiable. In vitro, the carcinogenic potential of natural crystalline and amorphous silica particles has been revealed by the Syrian Hamster Embryo (SHE) cell transformation assay. On the other hand, the genotoxic potential of those substances has not been investigated in SHE cells. And yet, genotoxicity assays are commonly used for hazard evaluation and they are often used as in vitro assays of reference to predict a possible carcinogenic potential. The main objective of this study was to compare the genotoxic potential and the carcinogenic potential of different crystalline and amorphous silica particles in SHE cells. Three silica samples of different crystallinity were used: natural amorphous silica, partially crystallized silica and quartz silica particles. Their genotoxicity were tested through the in vitro micronucleus assay and the comet assay in SHE, and their carcinogenic potential through the SHE transformation assay. In addition, silica samples were also tested with the same genotoxicity assays in V79 hamster-lung cells, a common in vitro model for particle exposure. Results obtained in the micronucleus and the comet assays show that none of the silica was capable of inducing genotoxic effects in SHE cells and only the amorphous silica induced genotoxic effects in V79 cells. However in the SHE cell transformation assays, the partially crystallized and quartz silica were able to induce morphological cell transformation. Together, these data suggest that, in vitro, the short-term genotoxic assays alone are not sufficient to predict the hazard and the carcinogenic potential of this type of particles; SHE transformation assay appears a more reliable tool for this purpose and should be included in the "in vitro battery assays" for hazard

  4. Biocompatible mesoporous silica nanoparticles with different morphologies for animal cell membrane penetration

    SciTech Connect

    Trewyn, B.; Nieweg, J.; Zhao, Y,; Lin, V.

    2007-11-24

    Two MCM-41 type, fluorescein-labeled mesoporous silica nanomaterials (MSNs) consisting of spherical and tube-shaped particles were synthesized and characterized. Both materials have hexagonally arranged mesopores with high surface area (>950 m{sup 2}/g) and a narrow distribution of pore diameters. The cellular uptake efficiency and kinetics of both MSNs were measured in a cancer cell line (CHO) and a noncancerous cell line (fibroblasts) by flow cytometry and fluorescence confocal microscopy. The correlation between the particle morphology and aggregation of MSNs to the effectiveness of cellular uptake was investigated. We envision that our study on the morphology dependent endocytosis of MSNs would lead to future developments of efficient transmembrane nanodevices for intracellular sensing and gene/drug delivery.

  5. Uptake of silica covered Quantum Dots into living cells: Long term vitality and morphology study on hyaluronic acid biomaterials.

    PubMed

    D'Amico, Michele; Fiorica, Calogero; Palumbo, Fabio Salvatore; Militello, Valeria; Leone, Maurizio; Dubertret, Benoit; Pitarresi, Giovanna; Giammona, Gaetano

    2016-10-01

    Quantum Dots (QDs) are promising very bright and stable fluorescent probes for optical studies in the biological field but water solubility and possible metal bio-contamination need to be addressed. In this work, a simple silica-QD hybrid system is prepared and the uptake in bovine chondrocytes living cells without any functionalization of the external protective silica shield is demonstrated. Moreover, long term treated cells vitality (up to 14days) and the transfer of silica-QDs to the next cell generations are here reported. Confocal fluorescence microscopy was also used to determine the morphology of the so labelled cells and the relative silica-QDs distribution. Finally, we employ silica-QD stained chondrocytes to characterize, as proof of concept, hydrogels obtained from an amphiphilic derivative of hyaluronic acid (HA-EDA-C18) functionalized with different amounts of the RGD peptide. PMID:27287118

  6. Laser-induced damage morphology in fused silica at 1064 nm in the nanosecond regime

    NASA Astrophysics Data System (ADS)

    Chambonneau, Maxime; Diaz, Romain; Duchateau, Guillaume; Grua, Pierre; Natoli, Jean-Yves; Rullier, Jean-Luc; Lamaignère, Laurent

    2014-10-01

    The morphology of laser-induced damage sites at the exit surface of fused silica is tightly correlated to the mode composition of the nanosecond laser pulses at 1064 nm. In the single longitudinal mode (SLM) configuration, a molten and fractured central zone is surrounded by a funnel-shaped surface modification. Ring patterns surround the damage sites when these are initiated by multiple longitudinal modes (MLM) laser pulses. In this last mode configuration, the pulses temporal profiles as well as the damage ring patterns differ from pulse to pulse. The appearance chronology of the rings is found to be closely related to the temporal shape of the laser pulses. This supports that the damage morphology originates from the coupling of a laser-supported detonation wave propagating in air with an ablation mechanism in silica. In our experiments, the propagation speed of the detonation wave reaches about 20 km/s and scales as the cube root of the laser intensity, in good agreement with theory.

  7. Non-contact analysis of the adsorptive ink capacity of nano silica pigments on a printing coating base.

    PubMed

    Jiang, Bo; Huang, Yu Dong

    2014-01-01

    Near infrared spectra combined with partial least squares were proposed as a means of non-contact analysis of the adsorptive ink capacity of recording coating materials in ink jet printing. First, the recording coating materials were prepared based on nano silica pigments. 80 samples of the recording coating materials were selected to develop the calibration of adsorptive ink capacity against ink adsorption (g/m2). The model developed predicted samples in the validation set with r2  = 0.80 and SEP = 1.108, analytical results showed that near infrared spectra had significant potential for the adsorption of ink capacity on the recording coating. The influence of factors such as recording coating thickness, mass ratio silica: binder-polyvinyl alcohol and the solution concentration on the adsorptive ink capacity were studied. With the help of the near infrared spectra, the adsorptive ink capacity of a recording coating material can be rapidly controlled. PMID:25329464

  8. Non-Contact Analysis of the Adsorptive Ink Capacity of Nano Silica Pigments on a Printing Coating Base

    PubMed Central

    Jiang, Bo; Huang, Yu Dong

    2014-01-01

    Near infrared spectra combined with partial least squares were proposed as a means of non-contact analysis of the adsorptive ink capacity of recording coating materials in ink jet printing. First, the recording coating materials were prepared based on nano silica pigments. 80 samples of the recording coating materials were selected to develop the calibration of adsorptive ink capacity against ink adsorption (g/m2). The model developed predicted samples in the validation set with r2  = 0.80 and SEP  = 1.108, analytical results showed that near infrared spectra had significant potential for the adsorption of ink capacity on the recording coating. The influence of factors such as recording coating thickness, mass ratio silica: binder-polyvinyl alcohol and the solution concentration on the adsorptive ink capacity were studied. With the help of the near infrared spectra, the adsorptive ink capacity of a recording coating material can be rapidly controlled. PMID:25329464

  9. Glutaraldehyde-chitosan and poly (vinyl alcohol) blends, and fluorescence of their nano-silica composite films.

    PubMed

    Hu, Huawen; Xin, John H; Hu, Hong; Chan, Allan; He, Liang

    2013-01-01

    In this study, a commercial chitosan cross-linked with glutaraldehyde (GA-chitosan) having the autofluorescent property was effectively blended with a poly (vinyl alcohol) (PVA) matrix, in the formation of a transparent and fluorescent blend film. The fluorescent efficiency of the film was enhanced with red-shifted emission band by increasing the concentrations of the GA-chitosan and decreasing the PVA crystallinity. It was found that the incorporation of silica nanoparticles could further decrease the PVA crystallinity, enhance the fluorescent efficiency, and largely redshift the emission band, as compared with the neat GA-chitosan-PVA blend film. This fluorescent property could be finely tuned by careful doping of the silica nanoparticles and change of the PVA crystallinity. These phenomena could be reasonably explained by high extent of isolation of the fluorophores, increase of the stiffness of the fluorescent conjugated planar structure, and further decrease of the PVA crystallinity. In addition, the introduction of the nano-silica could improve the water and heat resistances of the GA-chitosan-PVA based silica nanocomposites. PMID:23044137

  10. Covalent Immobilization and Characterization of a Novel Pullulanase from Fontibacillus sp. Strain DSHK 107 onto Florisil® and Nano-silica for Pullulan Hydrolysis.

    PubMed

    Alagöz, Dilek; Yildirim, Deniz; Güvenmez, Hatice Korkmaz; Sihay, Damla; Tükel, S Seyhan

    2016-08-01

    A novel pullulanase partially purified from Fontibacillus sp. was covalently immobilized on Florisil® and nano-silica through both glutaraldehyde and (3-glycidyloxypropyl)trimethoxysilane spacer arms. The pullulanase immobilized on Florisil® and nano-silica through glutaraldehyde spacer arm showed 85 and 190 % activity of its free form, respectively, whereas no activity was observed when it was immobilized on the same supports through (3-glycidyloxypropyl)trimethoxysilane spacer arm. The maximum working pHs of both the immobilized pullulanases on Florisil® and nano-silica through glutaraldehyde spacer arm were determined as 5.0; however, the maximum working pH of the free pullulanase was pH 6.0. The maximum temperatures of all the pullulanase preparations were determined as 35 °C. The apparent K m values were 1.49, 1.54, and 0.59 mg/mL pullunan, respectively, for the free and immobilized pullulanases on Florisil® and nano-silica. The corresponding apparent V max values were 0.59, 1.53, and 1.57 U mg prot.(-1) min.(-1). Thermal stability of pullulanases immobilized on Florisil® and nano-silica was enhanced 6.5- and 15.6-folds, respectively at 35 °C and 6.6- and 16.0-folds, respectively, at 50 °C. The pullulanases immobilized on Florisil® and nano-silica protected 71 and 90 % of their initial activities after 10 reuses. PMID:27033091

  11. Preparation, characterization and luminescent properties of dense nano-silica hybrids loaded with 1,8-naphthalic anhydride.

    PubMed

    Wang, Jinpeng; Sun, Jihong; Li, Yuzhen; Wang, Feng

    2014-03-01

    Novel luminescent dense nano-silica hybrid materials (DNSS) modified with different amounts of (3-aminopropyl)triethoxysilane (APTES) and 1,8-naphthalic anhydride (NA) were successfully synthesized via two steps combined with post-grafting methods. Powder X-ray diffraction (XRD), N2-sorption analysis, Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), thermogravimetric analysis (TGA), photoluminescence (PL) spectroscopy and elemental analysis, as well as time-resolved decays were employed to characterize the resultant hybrid materials. The results revealed that luminescent organic molecules had been successfully loaded onto the amine-modified surface of nano-silica spheres. In addition, their fluorescence intensity and characteristic peak of emission spectra changed with increasing amount of APTES and NA additive. In particular, the characteristic peak showed a red shift from 390 to 450 nm, however, this was inconsistent with results calculated on the basis of the elemental analysis data, most probably because of the dispersion behaviors of NA molecules from the aggregating to the monolayer state. These observations demonstrated the existence of a quantum confinement effectiveness of NA-DNSS samples, and therefore a possible mechanism was put forward. PMID:23765586

  12. Effect of polyvinylpyrrolidone on mesoporous silica morphology and esterification of lauric acid with 1-butanol catalyzed by immobilized enzyme

    NASA Astrophysics Data System (ADS)

    Zhang, Jinyu; Zhou, Guowei; Jiang, Bin; Zhao, Minnan; Zhang, Yan

    2014-05-01

    Mesoporous silica materials with a range of morphology evolution, i.e., from curved rod-shaped mesoporous silica to straight rod-shaped mesoporous silica, were successfully prepared using polyvinylpyrrolidone (PVP) and triblock copolymer as dual template. The effects of PVP molecular weight and concentration on mesoporous silica structure parameters were studied. Results showed that surface area and pore volume continuously decreased with increased PVP molecular weight. Mesoporous silica prepared with PVP K30 also possessed larger pore diameter, interplanar spacing (d100), and cell parameter (a0) than that prepared with PVP K15 and PVP K90. In addition, with increased PVP concentration, d100 and a0 continuously decreased. The mechanism of morphology evolution caused by the change in PVP concentration was investigated. The conversion rate of lauric acid with 1-butanol catalyzed by immobilized Porcine pancreatic lipase (PPL) was also evaluated. Results showed that PPL immobilized on amino-functionalized straight rod-shaped mesoporous silica maintained 50% of its esterification conversion rate even after five cycles of use with a maximum conversion rate was about 90.15%.

  13. Nano rough micron patterned titanium for directing osteoblast morphology and adhesion

    PubMed Central

    Puckett, Sabrina; Pareta, Rajesh; Webster, Thomas J

    2008-01-01

    Previous studies have demonstrated greater functions of osteoblasts (bone-forming cells) on nanophase compared with conventional metals. Nanophase metals possess a biologically inspired nanostructured surface that mimics the dimensions of constituent components in bone, including collagen and hydroxyapatite. Not only do these components possess dimensions on the nanoscale, they are aligned in a parallel manner creating a defined orientation in bone. To date, research has yet to evaluate the effect that organized nanosurface features can have on the interaction of osteoblasts with material surfaces. Therefore, to determine if surface orientation of features can mediate osteoblast adhesion and morphology, this study investigated osteoblast function on patterned titanium substrates containing alternating regions of micron rough and nano rough surfaces prepared by novel electron beam evaporation techniques. This study was also interested in determining whether or not the size of the patterned regions had an effect on osteoblast behavior and alignment. Results indicated early controlled osteoblast alignment on these patterned materials as well as greater osteoblast adhesion on the nano rough regions of these patterned substrates. Interestingly, decreasing the width of the nano rough regions (from 80 μm to 22 μm) on these patterned substrates resulted in a decreased number of osteoblasts adhering to these areas. Changes in the width of the nano rough regions also resulted in changes in osteoblast morphology, thus, suggesting there is an optimal pattern dimension that osteoblasts prefer. In summary, results of this study provided evidence that aligned nanophase metal features on the surface of titanium improved early osteoblast functions (morphology and adhesion) promising for their long term functions, criteria necessary to improve orthopedic implant efficacy. PMID:18686782

  14. Effect of morphology and solvent on two-photon absorption of nano zinc oxide

    SciTech Connect

    Kavitha, M.K.; Haripadmam, P.C.; Gopinath, Pramod; Krishnan, Bindu; John, Honey

    2013-05-15

    Highlights: ► ZnO nanospheres and triangular structures synthesis by novel precipitation technique. ► The effect of precursor concentration on the size and shape of nano ZnO. ► Open aperture Z-scan measurements of the ZnO nanoparticle dispersions. ► Nanospheres exhibit higher two photon absorption coefficient than triangular nanostructures. ► Nanospheres dispersed in water exhibit higher two photon absorption coefficient than its dispersion in 2-propanol. - Abstract: In this paper, we report the effect of morphology and solvent on the two-photon absorption of nano zinc oxide. Zinc oxide nanoparticles in two different morphologies like nanospheres and triangular nanostructures are synthesized by novel precipitation technique and their two-photon absorption coefficient is measured using open aperture Z-scan technique. Experimental results show that the zinc oxide nanospheres exhibit higher two-photon absorption coefficient than the zinc oxide triangular nanostructures. The zinc oxide nanospheres dispersed in water exhibit higher two-photon absorption coefficient than that of its dispersion in 2-propanol. The zinc oxide nanospheres dispersed in water shows a decrease in two-photon absorption coefficient with an increase in on-axis irradiance. The result confirms the dependence of shape and solvent on the two-photon absorption of nano zinc oxide.

  15. The influence of molybdenum disulfide nanoplatelets on the dispersion of nano silica in natural rubber composites

    NASA Astrophysics Data System (ADS)

    Weng, Peijin; Wei, Qiuyan; Tang, Zhenghai; Lin, Tengfei; Guo, Baochun

    2015-12-01

    The dispersion of nanofiller in polymer composites is critical in governing the ultimate performances. Present study aimed to improve the dispersion of silica in elastomeric materials based on natural rubber (NR) composites using the nanoplatelets of molybdenum disulfide (MoS2), a graphene-like layered inorganic. NR latex was co-coagulated with MoS2 suspension to form NR/MoS2 compounds (1∼5 phr). Then silica (30 phr) was incorporated into NR/MoS2 compounds, followed by curing with sulfur, to obtained NR/MoS2/silica composites. The dispersion state of silica in the composites was examined by TEM and the effects of MoS2 on the performance of the composites were investigated. It was found that a small amount of MoS2 nanoplatelets significantly improved the silica dispersion. Consequently, the static and dynamic mechanical properties of the crosslinked natural rubber materials were greatly enhanced. The improved dispersion of silica is associated with charge transfer interaction, giving rise to electrostatic repulsion among silica.

  16. Syntheses and characterization of AgI nano-structures by ultrasonic method: Different morphologies under different conditions.

    PubMed

    Abbasi, Amir Reza; Morsali, Ali

    2010-03-01

    Nano-structures of AgI have been prepared by reaction between AgNO(3) and KI under ultrasound irradiation. Some of parameters such as effect of stirring, temperature, sonicating time in growth and morphology of the nano-structures have been studied. The sizes distributions depend slighter on reaction conditions. But, morphology of nano-structure depends strongly on reaction parameters. With change of solvent concentration and sonicating time, nanoparticles structures changed to nanowires. An increasing of temperature results in an increasing of solubility. As a result, nuclei with small sizes become unstable and dissolve back into the solution. Attendance or non-attendance of stirring is another parameter that effects on morphology of nano-structures. In some conditions, non-attendance of stirring led to nanowires structure and in the other conditions, nanoparticles structures were prepared. The samples were characterized with powder X-ray diffraction (XRD), scanning electron microscopy (SEM). PMID:19959390

  17. Morphological Analysis of Physically Reconstructed Silica Monoliths with Submicrometer Macropores: Effect of Decreasing Domain Size on Structural Homogeneity.

    PubMed

    Stoeckel, Daniela; Kübel, Christian; Loeh, Marc O; Smarsly, Bernd M; Tallarek, Ulrich

    2015-07-01

    Silica monoliths are increasingly used as fixed-bed supports in separation and catalysis because their bimodal pore space architecture combines excellent mass transport properties with a large surface area. To optimize their performance, a quantitative relationship between morphology and transport characteristics has to be established, and synthesis conditions that lead to a desired morphology optimized for a targeted application must be identified. However, the effects of specific synthesis parameters on the structural properties of silica monoliths are still poorly understood. An important question is how far the macropore and domain size can be reduced without compromising the structural homogeneity. We address this question with quantitative morphological data derived for a set of eight macroporous-mesoporous silica monoliths with an average macropore size (d(macro)) of between 3.7 and 0.1 μm, prepared following an established route involving the sol-gel transition and phase separation. The macropore space of the silica monolith samples is reconstructed using focused ion beam scanning electron microscopy followed by a quantitative assessment of geometrical and topological properties based on chord length distributions (CLDs) and branch-node analysis of the pore network, respectively. We observe a significant increase in structural heterogeneity, indicated by a decrease in the parameter k derived from fitting a k-gamma function to the CLDs, when d(macro) reaches the submicrometer range. The compromised structural homogeneity of silica monoliths with submicrometer macropores could possibly originate from early structural freezing during the competitive processes of sol-gel transition and phase separation. It is therefore questionable if the common approach of reducing the morphological features of silica monoliths into the submicrometer regime by changing the point of sol-gel transition can be successful. Alternative strategies and a better understanding of the

  18. Cetuximab-modified mesoporous silica nano-medicine specifically targets EGFR-mutant lung cancer and overcomes drug resistance.

    PubMed

    Wang, Yuetong; Huang, Hsin-Yi; Yang, Liu; Zhang, Zhanxia; Ji, Hongbin

    2016-01-01

    Drug resistance to tyrosine kinase inhibitor (TKI) is the main obstacle for efficient treatment of epidermal growth factor receptor (EGFR)-mutant lung cancer patients. Here we design a cetuximab-capped mesoporous silica nanoparticle (MP-SiO2 NP) as the drug carrier to specifically target EGFR-mutant lung cancer cells and efficiently release loaded drugs including doxorubicin and gefitinib. This innovative nano-medicine can specifically target lung cancer cells with high EGFR expression rather than those with low EGFR level. Treatment of a gefitinib-resistant cell line derived from PC9 cell (PC9-DR) with the gefitinib-loaded cetuximab-capped MP-SiO2 NP showed a significant inhibition of cell growth. Moreover, this nano-medicine successfully suppressed the progression of PC9-DR xenograft tumors. This tumor suppression was due to the endocytosis of large amount of nano-medicine and the effective gefitinib release induced by high glutathione (GSH) level in PC9-DR cells. Collectively, our study provides a novel approach to overcome EGFR-TKI resistance using cetuximab modified MP-SiO2 NP, which holds strong potential for effective management of EGFR-mutant lung cancer. PMID:27151505

  19. Cetuximab-modified mesoporous silica nano-medicine specifically targets EGFR-mutant lung cancer and overcomes drug resistance

    PubMed Central

    Wang, Yuetong; Huang, Hsin-Yi; Yang, Liu; Zhang, Zhanxia; Ji, Hongbin

    2016-01-01

    Drug resistance to tyrosine kinase inhibitor (TKI) is the main obstacle for efficient treatment of epidermal growth factor receptor (EGFR)-mutant lung cancer patients. Here we design a cetuximab-capped mesoporous silica nanoparticle (MP-SiO2 NP) as the drug carrier to specifically target EGFR-mutant lung cancer cells and efficiently release loaded drugs including doxorubicin and gefitinib. This innovative nano-medicine can specifically target lung cancer cells with high EGFR expression rather than those with low EGFR level. Treatment of a gefitinib-resistant cell line derived from PC9 cell (PC9-DR) with the gefitinib-loaded cetuximab-capped MP-SiO2 NP showed a significant inhibition of cell growth. Moreover, this nano-medicine successfully suppressed the progression of PC9-DR xenograft tumors. This tumor suppression was due to the endocytosis of large amount of nano-medicine and the effective gefitinib release induced by high glutathione (GSH) level in PC9-DR cells. Collectively, our study provides a novel approach to overcome EGFR-TKI resistance using cetuximab modified MP-SiO2 NP, which holds strong potential for effective management of EGFR-mutant lung cancer. PMID:27151505

  20. Preparation of silica nanospheres and porous polymer membranes with controlled morphologies via nanophase separation

    PubMed Central

    2012-01-01

    We successfully synthesized two different structures, silica nanospheres and porous polymer membranes, via nanophase separation, based on a sol–gel process. Silica sol, which was in situ polymerized from tetraorthosilicate, was used as a precursor. Subsequently, it was mixed with a polymer that was used as a matrix component. It was observed that nanophase separation occurred after the mixing of polymer with silica sol and subsequent evaporation of solvents, resulting in organizing various structures, from random network silica structures to silica spheres. In particular, silica nanospheres were produced by manipulating the mixing ratio of polymer to silica sol. The size of silica beads was gradually changed from micro- to nanoscale, depending on the polymer content. At the same time, porous polymer membranes were generated by removing the silica component with hydrofluoric acid. Furthermore, porous carbon membranes were produced using carbon source polymer through the carbonization process. PMID:22873570

  1. Refractive index detection range adjustable liquid-core fiber optic sensor based on surface plasmon resonance and a nano-porous silica coating

    NASA Astrophysics Data System (ADS)

    Chen, Yuzhi; Li, Xuejin; Zhou, Huasheng; Hong, Xueming; Geng, Youfu

    2016-09-01

    A liquid-core fiber optic surface plasmon resonance sensor with an adjustable nano-porous silica coating is first presented in this paper. By adjusting the refractive index of the nano-porous silica coating, the sensor can be used in different refractive index detection ranges. A low refractive index interval of 1.33–1.34 and a high refractive index interval of 1.42–1.44 are taken as examples to be investigated. Results show that our sensor works well in these two intervals by using appropriate nano-porous silica coatings. The highest sensitivities of the low and high refractive index intervals are obtained to be 5840 nm/RIU and 5120 nm/RIU, respectively. In addition, the sensing performances and the working wavelengths can be adjusted to meet different working requirements by changing the refractive index of the nano-porous silica coating. We also take the single mode incidence cases to explain the effects of different single incident light modes on the sensing performances.

  2. Morphologies of laser-induced damage in hafnia-silica multilayer mirror and polarizer coatings

    SciTech Connect

    Genin, F.Y.; Stolz, C.J.

    1996-08-01

    Hafnium-silica multilayer mirrors and polarizers were deposited by e-beam evaporation onto BK7 glass substrates. The mirrors and polarizers were coated for operation at 1053 nm at 45{degree} and at Brewster`s angle (56{degree}), respectively. They were tested with a single 3-ns laser pulse. Morphology of the laser-induced damage was characterized by optical and scanning electron microscopy. Four distinct damage morphologies were found: pits, flatbottom pits, scalds, and delaminates. The pits and flat bottom pits (<30{mu}m dia) were detected at lower fluences (as low as 5 J/cm{sup 2}). The pits seemed to result from ejection of nodular defects by causing local enhancement of the electric field. Scalds and delaminates could be observed at higher fluences (above 13 J/cm{sup 2}) and seemed to result from the formation of plasmas on the surface. These damage types often originated at pits and were less than 300 {mu}m diameter; their size increased almost linearly with fluence. Finally, effects of the damage on the beam (reflectivity degradation and phase modulations) were measured.

  3. Assessment of angiogenesis in osseointegration of a silica-collagen biomaterial using 3D-nano-CT.

    PubMed

    Alt, Volker; Kögelmaier, Daniela Vera; Lips, Katrin S; Witt, Vera; Pacholke, Sabine; Heiss, Christian; Kampschulte, Marian; Heinemann, Sascha; Hanke, Thomas; Thormann, Ulrich; Schnettler, Reinhard; Langheinrich, Alexander C

    2011-10-01

    Bony integration of biomaterials is a complex process in which angiogenesis plays a crucial role. We evaluated micro- and nano-CT imaging to demonstrate and quantify neovascularization in bony integration of a biomaterial and to give an image based estimation for the needed resolution for imaging angiogenesis in an animal model of femora defect healing. In 8 rats 5mm full-size defects were created at the left femur that was filled with silica-collagen bone substitute material and internally fixed with plate osteosynthesis. After 6 weeks the femora were infused in situ with Microfil, harvested and scanned for micro-CT (9 μm)(3) and nano-CT (3 μm)(3) imaging. Using those 3D images, the newly formed blood vessels in the area of the biomaterial were assessed and the total vascular volume fraction, the volume of the bone substitute material and the volume of the bone defect were quantitatively characterized. Results were complemented by histology. Differences were statistically assessed using (ANOVA). High-resolution nano-CT demonstrated new blood vessel formation surrounding the biomaterial in all animals at capillary level. Immunohistochemistry confirmed the newly formed blood vessels surrounding the bone substitute material. The mean vascular volume fraction (VVF) around the implant was calculated to be 3.01 ± 0.4%. The VVF was inversely correlated with the volume of the bone substitute material (r=0.8) but not with the dimension of the fracture zone (r=0.3). Nano-CT imaging is feasible for quantitative analysis of angiogenesis during bony integration of biomaterials and a promising tool in this context for the future. PMID:21723963

  4. The effect of ultrasonication on the size and morphology of iron oxide - chitosan nano and microparticles

    SciTech Connect

    Akın, Deniz; Yakar, Arzu; Gündüz, Ufuk

    2013-12-16

    The aim of this study is to synthesize magnetic Fe{sub 3}O{sub 4}-chitosan nano and microparticles (Fe{sub 3}O{sub 4}-CPs) by suspension cross-linking and ionic gelation methods and investigate the effect of ultrasonication on the size, morphology and magnetic properties. The synthesized particles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS) and vibrating sample magnetometry (VSM). The results showed that the ultrasonication decreased the mean particle diameter and enhanced magnetic properties of Fe{sub 3}O{sub 4}-CPs due to the Fe{sub 3}O{sub 4} content.

  5. Nano-silica fabricated with silver nanoparticles: antifouling adsorbent for efficient dye removal, effective water disinfection and biofouling control

    NASA Astrophysics Data System (ADS)

    Das, Sujoy K.; Khan, Md. Motiar R.; Parandhaman, T.; Laffir, Fathima; Guha, Arun K.; Sekaran, G.; Mandal, Asit Baran

    2013-05-01

    A nano-silica-AgNPs composite material is proposed as a novel antifouling adsorbent for cost-effective and ecofriendly water purification. Fabrication of well-dispersed AgNPs on the nano-silica surface, designated as NSAgNP, has been achieved through protein mediated reduction of silver ions at ambient temperature for development of sustainable nanotechnology. The coated proteins on AgNPs led to the formation of stable NSAgNP and protected the AgNPs from oxidation and other ions commonly present in water. The NSAgNP exhibited excellent dye adsorption capacity both in single and multicomponent systems, and demonstrated satisfactory tolerance against variations in pH and dye concentration. The adsorption mainly occurred through electrostatic interaction, though π-π interaction and pore diffusion also contributed to the process. Moreover, the NSAgNP showed long-term antibacterial activity against both planktonic cells and biofilms of Gram-negative Escherichia coli and Pseudomonas aeruginosa. The antibacterial activity of AgNPs retarded the initial attachment of bacteria on NSAgNP and thus significantly improved the antifouling properties of the nanomaterial, which further inhibited biofilm formation. Scanning electron and fluorescence microscopic studies revealed that cell death occurred due to irreversible damage of the cell membrane upon electrostatic interaction of positively charged NSAgNP with the negatively charged bacterial cell membrane. The high adsorption capacity, reusability, good tolerance, removal of multicomponent dyes and E. coli from the simulated contaminated water and antifouling properties of NSAgNP will provide new opportunities to develop cost-effective and ecofriendly water purification processes.A nano-silica-AgNPs composite material is proposed as a novel antifouling adsorbent for cost-effective and ecofriendly water purification. Fabrication of well-dispersed AgNPs on the nano-silica surface, designated as NSAgNP, has been achieved through

  6. Nano-silica fabricated with silver nanoparticles: antifouling adsorbent for efficient dye removal, effective water disinfection and biofouling control.

    PubMed

    Das, Sujoy K; Khan, Md Motiar R; Parandhaman, T; Laffir, Fathima; Guha, Arun K; Sekaran, G; Mandal, Asit Baran

    2013-06-21

    A nano-silica-AgNPs composite material is proposed as a novel antifouling adsorbent for cost-effective and ecofriendly water purification. Fabrication of well-dispersed AgNPs on the nano-silica surface, designated as NSAgNP, has been achieved through protein mediated reduction of silver ions at ambient temperature for development of sustainable nanotechnology. The coated proteins on AgNPs led to the formation of stable NSAgNP and protected the AgNPs from oxidation and other ions commonly present in water. The NSAgNP exhibited excellent dye adsorption capacity both in single and multicomponent systems, and demonstrated satisfactory tolerance against variations in pH and dye concentration. The adsorption mainly occurred through electrostatic interaction, though π-π interaction and pore diffusion also contributed to the process. Moreover, the NSAgNP showed long-term antibacterial activity against both planktonic cells and biofilms of Gram-negative Escherichia coli and Pseudomonas aeruginosa. The antibacterial activity of AgNPs retarded the initial attachment of bacteria on NSAgNP and thus significantly improved the antifouling properties of the nanomaterial, which further inhibited biofilm formation. Scanning electron and fluorescence microscopic studies revealed that cell death occurred due to irreversible damage of the cell membrane upon electrostatic interaction of positively charged NSAgNP with the negatively charged bacterial cell membrane. The high adsorption capacity, reusability, good tolerance, removal of multicomponent dyes and E. coli from the simulated contaminated water and antifouling properties of NSAgNP will provide new opportunities to develop cost-effective and ecofriendly water purification processes. PMID:23680871

  7. Effects of Nano-CeO₂ with Different Nanocrystal Morphologies on Cytotoxicity in HepG2 Cells.

    PubMed

    Wang, Lili; Ai, Wenchao; Zhai, Yanwu; Li, Haishan; Zhou, Kebin; Chen, Huiming

    2015-09-01

    Cerium oxide nanoparticles (nano-CeO₂) have been reported to cause damage and apoptosis in human primary hepatocytes. Here, we compared the toxicity of three types of nano-CeO₂ with different nanocrystal morphologies (cube-, octahedron-, and rod-like crystals) in human hepatocellular carcinoma cells (HepG2). The cells were treated with the nano-CeO₂ at various concentrations (6.25, 12.5, 25, 50, 100 μg/mL). The crystal structure, size and morphology of nano-CeO₂ were investigated by X-ray diffractometry and transmission electron microscopy. The specific surface area was detected using the Brunauer, Emmet and Teller method. The cellular morphological and internal structure were observed by microscopy; apoptotic alterations were measured using flow cytometry; nuclear DNA, mitochondrial membrane potential (MMP), reactive oxygen species (ROS) and glutathione (GSH) in HepG2 cells were measured using high content screening technology. The scavenging ability of hydroxyl free radicals and the redox properties of the nano-CeO₂ were measured by square-wave voltammetry and temperature-programmed-reduction methods. All three types of nano-CeO₂ entered the HepG2 cells, localized in the lysosome and cytoplasm, altered cellular shape, and caused cytotoxicity. The nano-CeO₂ with smaller specific surface areas induced more apoptosis, caused an increase in MMP, ROS and GSH, and lowered the cell's ability to scavenge hydroxyl free radicals and antioxidants. In this work, our data demonstrated that compared with cube-like and octahedron-like nano-CeO₂, the rod-like nano-CeO₂ has lowest toxicity to HepG2 cells owing to its larger specific surface areas. PMID:26404340

  8. Facile fabrication of nano-structured silica hybrid film with superhydrophobicity by one-step VAFS approach

    NASA Astrophysics Data System (ADS)

    Jia, Yi; Yue, Renliang; Liu, Gang; Yang, Jie; Ni, Yong; Wu, Xiaofeng; Chen, Yunfa

    2013-01-01

    Here we report a novel one-step vapor-fed aerosol flame synthesis (VAFS) method to attain silica hybrid film with superhydrophobicity on normal glass and other engineering material substrates using hexamethyldisiloxane (HMDSO) as precursor. The deposited nano-structured silica films represent excellent superhydrophobicity with contact angle larger than 150° and sliding angle below 5°, without any surface modification or other post treatments. SEM photographs proved that flame-made SiO2 nanoparticles formed dual-scale surface roughness on the substrates. It was confirmed by FTIR and XPS that the in situ formed organic fragments on the particle surface as species like (CH3)xSiO2-x/2 (x = 1, 2, 3) which progressively lowered the surface energy of fabricated films. Thus, these combined dual-scale roughness and lowered surface energy cooperatively produced superhydrophobic films. IR camera had been used to monitor the real-time flame temperature. It is found that the inert dilution gas inflow played a critical role in attaining superhydrophobicity due to its cooling and anti-oxidation effect. This method is facile and scalable for diverse substrates, without any requirement of complex equipments and multiple processing steps. It may contribute to the industrial fabrication of superhydrophobic films.

  9. A fluorescence ratiometric nano-pH sensor based on dual-fluorophore-doped silica nanoparticles

    NASA Astrophysics Data System (ADS)

    Gao, Feng; Tang, Lijuan; Dai, Lu; Wang, Lun

    2007-06-01

    We have synthesized dual-fluorophore-doped core-shell silica nanoparticles used as ratiometric pH sensor. The nanoparticles were prepared with a reverse microemulsion technique by simultaneously encapsulating two different fluorophores, the pH-sensitive dye fluorescein as a pH indicator and the pH-insensitive dye phenosafranine as an internal reference for fluorescence ratiometric measurement, into silica shell. The nanoparticles prevent the fluorescence dyes leaching from the silica matrix when immersed inside water. The hydrophilic silica shells were made by hydrolysing and polymerizing tetraethoxysilane (TEOS) in water-in-oil microemulsion. The fluorescence intensity ratio of the two dyes varied linearly as a function of pH in the range from 4.0 to 8.0. The sensor was also applied to measure pH of real water samples. The results are in good agreements with that using the conventional glass electrode method. The as-prepared fluorescent nanoparticles showed rapid response, excellent stability and high reproducibility as pH sensors.

  10. Outset of the Morphology of Nanostructured Silica Particles during Nucleation Followed by Ultrasmall-Angle X-ray Scattering.

    PubMed

    Schmitt, Julien; Kjellman, Tomas; Kwaśniewski, Paweł; Meneau, Florian; Pedersen, Jan Skov; Edler, Karen J; Rennie, Adrian R; Alfredsson, Viveka; Impéror-Clerc, Marianne

    2016-05-24

    Nucleation and growth of SBA-15 silica nanostructured particles with well-defined morphologies has been followed with time by small-angle X-ray scattering (SAXS) and ultrasmall-angle X-ray scattering (USAXS), using synchrotron radiation. Three different morphologies have been compared: platelets, toroids, and rods. SEM observations of the particles confirm that two key physical parameters control the morphology: the temperature and the stirring of the solution. USAXS curves demonstrate that primary particles with a defined shape are present very early in the reaction mixture, immediately after a very fast nucleation step. This nucleation step is detected at 10 min (56 °C) or 15 min (50 °C) after the addition of the silica precursor. The main finding is that the USAXS signal is different for each type of morphology, and we demonstrate that the difference is related to the shape of the particles, showing characteristic form factors for the different morphologies (platelet, toroid, and rod). Moreover, the size of the mesocrystal domains is correlated directly with the particle dimensions and shape. When stirred, aggregation between primary particles is detected even after 12 min (56 °C). The platelet morphology is promoted by constant stirring of the solution, through an oriented aggregation step between primary particles. In contrast, toroids and rods are only stabilized under static conditions. However, for toroids, aggregation is detected almost immediately after nucleation. PMID:27148887

  11. A new high-throughput method utilizing porous silica-based nano-composites for the determination of partition coefficients of drug candidates.

    PubMed

    Yu, Chih H; Tam, Kin; Tsang, Shik C

    2011-09-01

    We show that highly porous silica-based nanoparticles prepared via micro-emulsion and sol-gel techniques are stable colloids in aqueous solution. By incorporating a magnetic core into the porous silica nano-composite, it is found that the material can be rapidly separated (precipitated) upon exposure to an external magnetic field. Alternatively, the porous silica nanoparticles without magnetic cores can be equally separated from solution by applying a high-speed centrifugation. Using these silica-based nanostructures a new high-throughput method for the determination of partition coefficient for water/n-octanol is hereby described. First, a tiny quantity of n-octanol phase is pre-absorbed in the porous silica nano-composite colloids, which allows an establishment of interface at nano-scale between the adsorbed n-octanol with the bulk aqueous phase. Organic compounds added to the mixture can therefore undergo a rapid partition between the two phases. The concentration of drug compound in the supernatant in a small vial can be determined by UV-visible absorption spectroscopy. With the adaptation of a robotic liquid handler, a high-throughput technology for the determination of partition coefficients of drug candidates can be employed for drug screening in the industry based on these nano-separation skills. The experimental results clearly suggest that this new method can provide partition coefficient values of potential drug candidates comparable to the conventional shake-flask method but requires much shorter analytical time and lesser quantity of chemicals. PMID:21780284

  12. Silica xerogel-chitosan nano-hybrids for use as drug eluting bone replacement.

    PubMed

    Lee, Eun-Jung; Jun, Shin-Hee; Kim, Hyoun-Ee; Kim, Hae-Won; Koh, Young-Hag; Jang, Jun-Hyeog

    2010-01-01

    Silica xerogel-chitosan hybrids containing vancomycin were fabricated by the sol-gel process at room temperature and their potential as a drug eluting bone replacement was evaluated in terms of their mechanical properties and drug release behaviors. Regardless of the content of chitosan, all of the prepared hybrids had a uniform mesoporous structure, which would allow the effectual loading of vancomycin. As the content of chitosan was increased, the strength, strain to failure, and work of fracture of the hybrids were significantly enhanced, while the elastic modulus was decreased. These changes in the mechanical properties were mainly attributed to the mitigation of the brittleness of the silica xerogel through its hybridization with the flexible chitosan phase. In addition, the initial burst-effect was remarkably reduced by increasing the content of chitosan. The hybrids with more than 30% chitosan could release the vancomycin for an extended period of time in a controlled manner. PMID:19657594

  13. EPR in functional structures based on doped (nano, meso)-porous silica and titanium dioxide

    NASA Astrophysics Data System (ADS)

    Kassiba, A.; Makowska-Janusik, M.; Mehdi, A.

    2011-04-01

    EPR investigations are performed on mesoporous silica (SBA15) functionalized by Nickel-cyclam complexes (1,4,8,11-tetraazacyclotetradecane groups chelating nickel ions) and on mesoporous titanium dioxide with nitrogen doping. For functionalized silica, the magnetic behaviour of organometallic groups, their mutual interactions and dispersion in the host matrices are compared with respect to the doping rates and the synthesis procedures. The relaxation processes were analyzed from the thermal evolution of the paramagnetic spin susceptibilities and EPR line-widths. Particularly, some samples show the formation of clusters where phonon assisted one dimensional (1D) ferromagnetic ordering occurs below 45 K. For the mesoporous TiO2, systematic EPR investigations were performed on two main classes of materials with regard to the porosity degrees. The EPR experiments point out the efficiency of EPR method to probe the degree of functionalization of mesoporous silica or the nitrogen doping achievement in TiO2, and in general to give a valuable feedback to improve the synthesis routes of smart materials.

  14. Alendronate decorated nano hydroxyapatite in mesoporous silica: Cytotoxicity and osteogenic properties

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Liu, Weiqiang; She, Zhending; Wu, Hongkai; Shi, Xuetao

    2011-09-01

    Mesoporous silica is a promising drug delivery vehicle due to its large surface area and order porous structure. Hydroxyapatite-modified mesoporous silica materials (MSH) have been developed, and the cytotoxicity of MSH and unmodified mesoporous silica (HMS) has also been studied in this work. The results indicated that MSH exhibited lower cytotoxicity than HMS. The drug release property of MSH was also investigated in this paper. Alendronate (AL) was laden into MSH and HMS, respectively. MSH exhibited long release period lasting over 30 days with a weak burst release in the first 5 days; however, the AL release period of HMS was just 5 days with a remarkable burst release. In addition, the osteogenic commitment induced in human marrow mesenchymal stem cells (MSCs) by MSH-alendronate (MSH-AL) was also investigated, and the osteogenesis of MSCs was evaluated by alkaline phosphatase (ALP) assay. The osteogenesis of MSCs induced by MSH-AL is comparable to that induced by the osteogenic medium. Taken together, MSH can be severed as potential bone repair materials with lower cytotoxicity.

  15. Well-defined inorganic/organic nanocomposite by nano silica core-poly(methyl methacrylate/butylacrylate/trifluoroethyl methacrylate) shell.

    PubMed

    Chang, Gang; He, Ling; Zheng, Wei; Pan, Aizhao; Liu, Jing; Li, Yingjun; Cao, Ruijun

    2013-04-15

    The novel inorganic/organic core-shell SiO2/P(MMA/BA/3FMA) nanocomposite for coating application is synthesized in this paper by seed emulsion polymerization, in which the inorganic phase is composed of nano-SiO2 modified by vinyl-trimethoxysilane (VMS) or γ-methacryloxy propyl trimethoxylsilane (MPMS), and the organic phase is made of terpolymer by 2,2,2-trifluoroethyl methacrylate (3FMA), methyl methacrylate (MMA), and n-butyl acrylate (BA). The chemical structure of SiO2/P(MMA/BA/3FMA) is characterized by FTIR. The effect of surfactant polyvinylpyrrolidone (PVP), sodium dodecyl sulfate (SDS)/octyl phenyl polyoxyethylene ether (TX-10), sodium dodecyl benzene sulfonate (SDBS)/TX-10 and sodium hexametaphosphate (SHMP) on the grafting ratio (GR) of VMS and MPMS, the dispersion of nano-SiO2 particles and the film properties of SiO2/P(MMA/BA/3FMA) are investigated by TGA, DLS, TEM, SEM, and XPS. The morphology variation and the particle size distributions of SiO2/P(MMA/BA/3FMA) with the content of surfactant and P(MMA/BA/3FMA) are characterized. It is found that MPMS is more effective than VMS in improving GR and the dispersion of nano-SiO2 particles. The surfactants are favor of gaining the higher GR in the multilayer grafted nano-SiO2, especially SDS/TX-10 for 17.6% GR. The morphology of SiO2/P(MMA/BA/3FMA) is controlled by the amount of SDS/TX-10 and P(MMA/BA/3FMA) as the core-shell particles, the stacked pomegranate seed with multicore and the multicore-single shell structure when w(MMA)/w(BA)/w(3FMA)=1.3/1/1. Among the different surfactants, SDBS/TX-10 and PVP could give the monodispersing nano-SiO2 in the terpolymer matrix of the films, but SDS/TX-10 and SDBS/TX-10 could perform the fluorine-rich surface. PMID:23403111

  16. C18 silica packed capillary columns with monolithic frits prepared with UV light emitting diode: usefulness in nano-liquid chromatography and capillary electrochromatography.

    PubMed

    D'Orazio, Giovanni; Fanali, Salvatore

    2012-04-01

    In this paper the potential of fused silica capillaries packed with RP18 silica particles entrapped with monolithic frits using both nano-liquid chromatography (nano-LC) and capillary electrochromatography (CEC) was investigated. Frits were prepared after removing a short part of the polyimide layer on the capillary wall and irradiating the polymerization mixture with an UV-light emitter diode (LED) at 370 nm. The capillary, was rotated during the polymerization procedure in order to obtain a homogeneous monolith. The distance of the LED from the capillary and the exposure time to UV light were studied in order to obtain frits with good porosity and high robustness. A mixture containing five alkylbenzenes was selected as sample and analyzed by both nano-LC and CEC. The standard mixture was baseline separated with good efficiency in the range 78,000-93,000 and 99,000-113,000 plates/m in nano-LC and CEC, respectively. The columns resulted to be very robust and the prepared monolithic frits allowed working with backpressure as high as 400 bar (nano-LC). In addition high voltages were applied in CEC (25-30 kV) without bubbles formation in absence of pressure assistance during runs. PMID:22189300

  17. Investigation of nuclear nano-morphology marker as a biomarker for cancer risk assessment using a mouse model

    NASA Astrophysics Data System (ADS)

    Bista, Rajan K.; Uttam, Shikhar; Hartman, Douglas J.; Qiu, Wei; Yu, Jian; Zhang, Lin; Brand, Randall E.; Liu, Yang

    2012-06-01

    The development of accurate and clinically applicable tools to assess cancer risk is essential to define candidates to undergo screening for early-stage cancers at a curable stage or provide a novel method to monitor chemoprevention treatments. With the use of our recently developed optical technology--spatial-domain low-coherence quantitative phase microscopy (SL-QPM), we have derived a novel optical biomarker characterized by structure-derived optical path length (OPL) properties from the cell nucleus on the standard histology and cytology specimens, which quantifies the nano-structural alterations within the cell nucleus at the nanoscale sensitivity, referred to as nano-morphology marker. The aim of this study is to evaluate the feasibility of the nuclear nano-morphology marker from histologically normal cells, extracted directly from the standard histology specimens, to detect early-stage carcinogenesis, assess cancer risk, and monitor the effect of chemopreventive treatment. We used a well-established mouse model of spontaneous carcinogenesis--ApcMin mice, which develop multiple intestinal adenomas (Min) due to a germline mutation in the adenomatous polyposis coli (Apc) gene. We found that the nuclear nano-morphology marker quantified by OPL detects the development of carcinogenesis from histologically normal intestinal epithelial cells, even at an early pre-adenomatous stage (six weeks). It also exhibits a good temporal correlation with the small intestine that parallels the development of carcinogenesis and cancer risk. To further assess its ability to monitor the efficacy of chemopreventive agents, we used an established chemopreventive agent, sulindac. The nuclear nano-morphology marker is reversed toward normal after a prolonged treatment. Therefore, our proof-of-concept study establishes the feasibility of the SL-QPM derived nuclear nano-morphology marker OPL as a promising, simple and clinically applicable biomarker for cancer risk assessment and

  18. Study of blend composition of nano silica under the influence of neutron flux

    NASA Astrophysics Data System (ADS)

    Huseynov, Elchin; Garibov, Adil; Mehdiyeva, Ravan

    2014-08-01

    Nano SiO2 compound with 160 m2/g specific surface area and 20 nm sizes has been irradiated continuously with neutron flux up to 20 hours in various periods in TRIGA Mark II type research reactor. The initial activities of different type radionuclides defined in the result of eight day activity analysis changes between wide range of 1,5 kBq- 1,5GBq. In the result of activity analysis carried out after the irradiation, the element content of 0,5% mixture existing in nano SiO2 compound has been defined with radionuclides of relevant element. It has been defined percentage amounts of elements in blend composition according to the performed activities.

  19. Nano-Structured Mesoporous Silica Wires with Intra-Wire Lamellae via Evaporation-Induced Self-Assembly in Space-Confined Channels

    SciTech Connect

    Hu, Michael Z.; Shi, Donglu; Blom, Douglas Allen

    2014-04-06

    Evaporation-induced self-assembly (EISA) of silica sol-gel ethanol-water solution mixtures with block-copolymer were studied inside uniform micro/nano channels. Nano-structured mesoporous silica wires, with various intra-wire self-assembly structures including lamellae, were prepared via EISA process but in space-confined channels with the diameter ranging from 50 nm to 200 nm. Membranes made of anodized aluminum oxide (AAO) and track-etched polycarbonate (EPC) were utilized as the arrays of space-confined channels (i.e., 50, 100, and 200-nm EPC and 200-nm AAO) for infiltration and drying of mixture solutions; these substrate membranes were submerged in mixture solutions consisting of a silica precursor, a structure-directing agent, ethanol, and water. After the substrate channels were filled with the solution under vacuum impregnation, the membrane was removed from the solution and dried in air. The silica precursor used was tetra-ethyl othosilicate (TEOS), and the structure-directing agent employed was triblock copolymer Pluronic-123 (P123). It was found that the formation of the mesoporous nanostructures in silica wires within uniform channels were significantly affected by the synthesis conditions including (1) pre-assemble TEOS aging time, (2) the evaporation rate during the vacuum impregnation, and (3) the air-dry temperature. The obtained intra-wire structures, including 2D-hexagonal rods and lamellae, were studied by scanning transmission electron microscopy (STEM). A steric hindrance effect seems to explain well the observed polymer-silica mesophase formation tailored by TEOS aging time. The evaporation effect, air-drying effect, and AAO-vs-EPC substrate effect on the mesoporous structure of the formed silica wires were also presented and discussed.

  20. Effect of nano-sized oxide particles on thermal and electrical properties of epoxy silica composites

    NASA Astrophysics Data System (ADS)

    Lee, Sang Heon; Choi, Yong

    2014-12-01

    Polymer matrix composites were fabricated using a modified injection molding technique in which nano-sized silicon oxides, titanium oxides, and aluminium oxides were contained. Nano-sized oxides were uniformly distributed in the composites produced by modified injection molding combining vacuum degassing and curing at a moderate temperature. The thermal decomposition and evaporation of the epoxy resin matrix depended on the composition of the composites. The relative permittivity of the nano-sized silicon carbide-epoxy composites increased from 5.16 to 5.37 by adding 2.0 wt % titanium oxide. The addition of titanium oxide of up to 2.0 wt % had little influence on the permittivity. The addition of 2.0 wt % of titanium oxide to epoxy resin showed the maximum thermal properties. Both the thermal conductivity and thermal diffusivity of the silicon oxide-epoxy composites tended to increase with titanium oxide content. The maximum thermal conductivity was observed in the composites with 2.0 wt % titanium oxide.

  1. Development of early diagenetic silica and quartz morphologies — Examples from the Siri Canyon, Danish North Sea

    NASA Astrophysics Data System (ADS)

    Weibel, Rikke; Friis, Henrik; Kazerouni, Afsoon Moatari; Svendsen, Johan B.; Stokkendal, Jesper; Poulsen, Mette Lise K.

    2010-07-01

    The Siri Canyon has proved to be a perfect area for investigating various morphologies of diagenetic silica in sandstones. The development in silica morphologies can be observed from very shallow (˜ 1700 m) to increased burial depth (˜ 3000 m) and increased proximity to the Central Graben (distance from 0 to 65 km). Hydrocarbons and pore fluids, now found in the Siri Fairway, have (at least partly) originated from the Central Graben. The Siri Canyon is a submarine canyon system eroded into the uppermost chalk deposits and filled with Palaeogene hemipelagic and turbiditic marls and mudstones interbedded with sandstone units deposited from sandy mass-flows and sandy turbidites, which originated on the Stavanger Platform. Several hydrocarbon exploration and production wells have been drilled in the Siri Canyon, seven of which are included in this study (Nini-3, Nini-1, NA-2P, Sofie-1, Siri-4, Celilie-1A and Augusta-1). The reservoir sandstones in these wells all contain authigenic silica of various morphologies identified with a combination of traditional optical microscopy and scanning electron microscopy. The silica morphologies in some places are classic and well-documented in the literature, whereas others, at least to our knowledge, have never previously been described. Some of the silica morphologies presented here show gradual transition from one to another, and others are stand-alone forms without clear relationships to other forms. The silica morphologies can be expressed in the following way: Opal rims; characteristic of the initial phase of the silica diagenesis in most sandstone units in the Siri Canyon. Thick opal rims characterise the sandstone parts adjacent to the mudstone units in the Stine segment of the Siri Field. Microquartz (quartz crystals with a size of 1-5 µm); seen as coatings on the opal rims, both ordered and random. Cavity overgrowth; found as quartz outgrowths in circular and angular cavities formed by dissolution of early authigenic

  2. Controlled deposition of functionalized silica coated zinc oxide nano-assemblies at the air/water interface for blood cancer detection.

    PubMed

    Pandey, Chandra Mouli; Dewan, Srishti; Chawla, Seema; Yadav, Birendra Kumar; Sumana, Gajjala; Malhotra, Bansi Dhar

    2016-09-21

    We report results of the studies relating to controlled deposition of the amino-functionalized silica-coated zinc oxide (Am-Si@ZnO) nano-assemblies onto an indium tin oxide (ITO) coated glass substrate using Langmuir-Blodgett (LB) technique. The monolayers have been deposited by transferring the spread solution of Am-Si@ZnO stearic acid prepared in chloroform at the air-water interface, at optimized pressure (16 mN/m), concentration (10 mg/ml) and temperature (23 °C). The high-resolution transmission electron microscopic studies of the Am-Si@ZnO nanocomposite reveal that the nanoparticles have a microscopic structure comprising of hexagonal assemblies of ZnO with typical dimensions of 30 nm. The surface morphology of the LB multilayer observed by scanning electron microscopy shows uniform surface of the Am-Si@ZnO film in the nanometer range (<80 nm). These electrodes have been utilized for chronic myelogenous leukemia (CML) detection by covalently immobilizing the amino-terminated oligonucleotide probe sequence via glutaraldehyde as a crosslinker. The response studies of these fabricated electrodes carried out using electrochemical impedance spectroscopy show that this Am-Si@ZnO LB film based nucleic acid sensor exhibits a linear response to complementary DNA (10(-6)-10(-16) M) with a detection limit of 1 × 10(-16) M. This fabricated platform is validated with clinical samples of CML positive patients and the results demonstrate its immense potential for clinical diagnosis. PMID:27590542

  3. MicroSPE-nanoLC-ESI-MS/MS Using 10-μm-i.d. Silica-Based Monolithic Columns for Proteomics

    SciTech Connect

    Luo, Quanzhou; Page, Jason S.; Tang, Keqi; Smith, Richard D.

    2007-01-01

    Silica-based monolithic narrow bore capillary columns (25 cm x 10 µm i.d.) with an integrated nanoESI emitter has been developed to provide high quality and robust microSPE-nanoLC-ESI-MS analyses. The integrated nanoESI emitter adds no dead volume to the LC separation, allowing stable electrospray performance to be obtained at flow rates of ~10 nL/min. In an initial application we identified 5510 unique peptides covering 1443 distinct Shewanella oneidensis proteins from a 300 ng tryptic digest sample in a single 4-h LC-MS/MS analysis using a linear ion trap MS (LTQ). We found the use of an integrated monolithic ESI emitter provided enhanced resistance to clogging and good run-to-run reproducibility.

  4. Effect of Ammonia Concentration on Silica Spheres Morphology and Solution Hydroxyl Concentration in Stober Process.

    PubMed

    Zeng, Dejun; Zhang, Haihong; Wang, Bo; Sang, Kezheng; Yang, Jianfeng

    2015-09-01

    Ammonia was used as catalyst to synthesize spherical silica particles by Stober process. More details about the effect of ammonia concentration on the silica powders were investigated. With increase of ammonia concentration from 0.05 to 1.75 mol/L, it was found that particle size increased from 0.068 to 0.91 μm and number density of silica particles decreased rapidly from 9242.40 x 10(10) to 4.62 x 10(10)/mL. Besides, the ratio of standard deviation and the particle size decreased with the increase of ammonia concentration. These results were well consistent with prediction of aggregation model. It was proved that ammonia resulted in persistently high pH values of solutions, which were vital to form large silica spheres. In the formation process of silica spheres, solution hydroxyl concentration was reduced, which might be attributed to transfer of negative charge in hydroxyl groups to silica spheres. PMID:26716345

  5. Nano-Crystalline Diamond Films with Pineapple-Like Morphology Grown by the DC Arcjet vapor Deposition Method

    NASA Astrophysics Data System (ADS)

    Li, Bin; Zhang, Qin-Jian; Shi, Yan-Chao; Li, Jia-Jun; Li, Hong; Lu, Fan-Xiu; Chen, Guang-Chao

    2014-08-01

    A nano-crystlline diamond film is grown by the dc arcjet chemical vapor deposition method. The film is characterized by scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), x-ray diffraction (XRD) and Raman spectra, respectively. The nanocrystalline grains are averagely with 80 nm in the size measured by XRD, and further proven by Raman and HRTEM. The observed novel morphology of the growth surface, pineapple-like morphology, is constructed by cubo-octahedral growth zones with a smooth faceted top surface and coarse side surfaces. The as-grown film possesses (100) dominant surface containing a little amorphous sp2 component, which is far different from the nano-crystalline film with the usual cauliflower-like morphology.

  6. Morphologies and wetting properties of copper film with 3D porous micro-nano hierarchical structure prepared by electrochemical deposition

    NASA Astrophysics Data System (ADS)

    Wang, Hongbin; Wang, Ning; Hang, Tao; Li, Ming

    2016-05-01

    Three-dimensional porous micro-nano hierarchical structure Cu films were prepared by electrochemical deposition with the Hydrogen bubble dynamic template. The morphologies of the deposited films characterized by Scanning Electronic Microscopy (SEM) exhibit a porous micro-nano hierarchical structure, which consists of three levels in different size scales, namely the honeycomb-like microstructure, the dendritic substructure and the nano particles. Besides, the factors which influenced the microscopic morphology were studied, including the deposition time and the additive Ethylene diamine. By measuring the water contact angle, the porous copper films were found to be super-hydrophobic. The maximum of the contact angles could reach as high as 162.1°. An empirical correlation between morphologies and wetting properties was revealed for the first time. The pore diameter increased simultaneously with the deposition time while the contact angle decreased. The mechanism was illustrated by two classical models. Such super-hydrophobic three-dimensional hierarchical micro-nano structure is expected to have practical application in industry.

  7. A new perspective of ablative pulsed laser propulsion: study on different morphologies of nano-structured ZnO

    NASA Astrophysics Data System (ADS)

    Ahmad, Muhammad Raza; Jamil, Yasir; Saeed, Humaima; Hussain, Tousif

    2015-05-01

    We report for the first time a new application of four different morphologies including nano-noodles of zinc oxide as a laser ablation micro-thruster. Nano-noodles represent a unique class of materials in which the electrons are confined near the surface owing to the majority of the near surface atoms. The synthesized samples of ZnO were of single phase, having a wurtzite hexagonal structure. Three different morphologies, viz. initial (nanoparticles), intermediate (nano-noodles) and final (complete nano-noodles) of zinc oxide were ablated using a Nd : YAG laser operating at 1064 nm for the measurement of propulsion parameters. The momentum coupling coefficient (Cm) and the specific impulse (Isp) were evaluated using the non-contact optical triangulation method. It has been observed that the morphology of the material affects the laser ablation propulsion (LAP) parameters. For each sample, the laser fluence for the optimum coupling coefficient owing to the plasma shielding effect has also been found. The synthesized nanostructured zinc oxide samples have been found useful as efficient laser propellants that can be used in a variety of applications due to diversity in their momentum coupling coefficient and specific impulse values.

  8. Effect of nano-alumina concentration on the mechanical, rheological, barrier and morphological properties of guar gum.

    PubMed

    Savvashe, Prashant; Kadam, Pravin; Mhaske, Shashank

    2016-04-01

    In this work, nano-alumina was utilized as a reinforcing agent for guar gum, with an aim to improve its performance properties; especially, mechanical and barrier i.e. water vapor transmission rate (WVTR). Films were prepared by the process of solution casting. Concentration of nano-alumina was varied as 0, 1, 3, 5 and 7 parts per hundred parts of resin (phr) in guar gum. The prepared pristine and guar gum/alumina nano-composite films were characterized for mechanical, puncture, x-ray diffraction, barrier, rheological and morphological properties. Tensile strength, Young's modulus, puncture strength, viscosity and crystallinity increased; whereas, WVTR, elongation at break (%) and damping factor decreased with increased concentration of nano-alumina in guar gum. However, optimized improvement in the performance properties were determined for 5 phr nano-alumina loaded guar gum polymer matrix, attributed to its better dispersion and interaction into the guar gum polymer chains due to the hydrophilic nature of both the materials. Above 5 phr concentration nano-alumina started forming aggregates, as evident from scanning electron microscopy. PMID:27413221

  9. Self-cleaning behavior in polyurethane/silica coatings via formation of a hierarchical packed morphology of nanoparticles

    NASA Astrophysics Data System (ADS)

    Hejazi, Iman; Mir Mohamad Sadeghi, Gity; Seyfi, Javad; Jafari, Seyed-Hassan; Khonakdar, Hossein Ali

    2016-04-01

    In the current research, a hierarchical morphology comprising of packed assembly of nanoparticles was induced in thermoplastic polyurethane (TPU)/silica nanocomposite coatings in order to achieve self-cleaning behavior. Moderately hydrophilic behavior of TPU hinders its transforming to a superhydrophobic material. In the presented method, a very thin layer of silica nanoparticles is applied to the surface of TPU sheets under elevated temperature and pressure. As temperature and pressure of the process remain unchanged, processing time was considered as a main variable. Based on scanning electron microscopy and confocal microscopy results, it was found that at a certain processing time, nanoparticles can form an utterly packed morphology leading to a self-cleaning behavior. Once the process was prolonged, TPU macromolecules found the chance to migrate onto the coating's top layer due to the enhanced mobility of chains at high temperature. This observation was further proved by X-ray photoelectron spectroscopy analysis and cross-sectional morphology. The presented method has promising potentials in transforming intrinsically hydrophilic polymers into superhydrophobic materials with self-cleaning behavior.

  10. Bioresponsive carbon nano-gated multifunctional mesoporous silica for cancer theranostics.

    PubMed

    Prasad, Rajendra; Aiyer, Sandhya; Chauhan, Deepak S; Srivastava, Rohit; Selvaraj, Kaliaperumal

    2016-02-28

    Designing bioresponsive nanocarriers for controlled and efficient intracellular drug release for cancer therapy is a major thrust area in nanomedicine. With recent recognition by the US FDA as a safe material for human trials, mesoporous silica nanoparticles (MSNPs) are being extensively explored as promising theranostic agents. Green fluorescent carbon quantum dots (CQDs), though known as possible alternatives for their more toxic and relatively less efficient predecessors, are less known as gate keepers for drug release control. We report for the first time an efficient bioresponse of CQDs when judiciously designed using glutathione cleavable (redox responsive) disulphide bonds. When the anticancer drug doxorubicin loaded MSNPs are capped with these CQDs, they display promising drug release control on exposure to a mimicked intracellular cancer environment. Their dual functionality is well established with good control on preventing the premature release and exceptional bio-imaging of HeLa cancer cells. Fluorescence images prove selective targeting of HeLa cells by overexpression of folate receptors from the surface functionalised folic acid ligand. Extensive characterisation using XRD, TEM, BET analysis, drug loading tests, drug release kinetics, MTT assay and fluoroscence cell imaging helps in understanding the multifunctionalities of the successful design, extending its scope with exciting prospects towards non-invasive targeted drug delivery and bio-imaging for effective cancer diagnosis and treatment. PMID:26753966

  11. Spontaneous gradual accumulation of hexagonally-aligned nano-silica on gold nanoparticles embedded in stabilized zirconia: a pathway from catalytic to NH3-sensing performance

    NASA Astrophysics Data System (ADS)

    Plashnitsa, Vladimir V.; Elumalai, Perumal; Fujio, Yuki; Kawaguchi, Toshikazu; Miura, Norio

    2011-05-01

    The present study highlights the influence of nano-impurities on the catalytic/sensing performance of nano-structured Au sensing-electrodes (SEs) housed in a quartz reactor and operated at high temperature over a long period of time. The planar sensor, made from a nano-structured Au-SE on a polished-polycrystalline (pp) yttria-stabilized zirconia (YSZ) substrate exhibited initially negligible electromotive force (emf) response to each of the examined gases (CO, CH4, C3H8, C3H6, NOx and NH3; 400 ppm each) at 700 °C in the presence of 5 vol.% oxygen and 5 vol.% water vapor. Such a poor emf response was attributed to the excellent gas-phase oxidation/reduction ability of Au nanoparticles embedded in the YSZ substrate at high temperature. The response of the planar sensor made up of nano-structured Au-SE was monitored for about 75 days at 700 °C. As a result of this long-term monitoring, we detected the appearance of highly sensitive and selective NH3 gas-sensing properties after 45-75 days of sensor operation. Detailed observation of the morphology and composition of the as-fabricated nano-structured Au-SE after 75 days operation at 700 °C revealed the gradual accumulation of hexagonally-aligned SiO2 nano-impurities on the surface of the Au nanoparticles. The NH3 sensing mechanism of the YSZ-based sensor using the spontaneously-formed composite (nano-Au + nano-SiO2)-SE is therefore proposed to be based on a strong acid-base interaction between gaseous NH3 and SiO2 nano-impurities, followed by spillover of adsorbed NH3 towards the nano-Au/pp-YSZ interface.

  12. Bioresponsive carbon nano-gated multifunctional mesoporous silica for cancer theranostics

    NASA Astrophysics Data System (ADS)

    Prasad, Rajendra; Aiyer, Sandhya; Chauhan, Deepak S.; Srivastava, Rohit; Selvaraj, Kaliaperumal

    2016-02-01

    Designing bioresponsive nanocarriers for controlled and efficient intracellular drug release for cancer therapy is a major thrust area in nanomedicine. With recent recognition by the US FDA as a safe material for human trials, mesoporous silica nanoparticles (MSNPs) are being extensively explored as promising theranostic agents. Green fluorescent carbon quantum dots (CQDs), though known as possible alternatives for their more toxic and relatively less efficient predecessors, are less known as gate keepers for drug release control. We report for the first time an efficient bioresponse of CQDs when judiciously designed using glutathione cleavable (redox responsive) disulphide bonds. When the anticancer drug doxorubicin loaded MSNPs are capped with these CQDs, they display promising drug release control on exposure to a mimicked intracellular cancer environment. Their dual functionality is well established with good control on preventing the premature release and exceptional bio-imaging of HeLa cancer cells. Fluorescence images prove selective targeting of HeLa cells by overexpression of folate receptors from the surface functionalised folic acid ligand. Extensive characterisation using XRD, TEM, BET analysis, drug loading tests, drug release kinetics, MTT assay and fluoroscence cell imaging helps in understanding the multifunctionalities of the successful design, extending its scope with exciting prospects towards non-invasive targeted drug delivery and bio-imaging for effective cancer diagnosis and treatment.Designing bioresponsive nanocarriers for controlled and efficient intracellular drug release for cancer therapy is a major thrust area in nanomedicine. With recent recognition by the US FDA as a safe material for human trials, mesoporous silica nanoparticles (MSNPs) are being extensively explored as promising theranostic agents. Green fluorescent carbon quantum dots (CQDs), though known as possible alternatives for their more toxic and relatively less efficient

  13. Effects of electrolytes and surfactants on the morphology and stability of advanced silver nano-materials

    SciTech Connect

    Obaid, Abdullah Yousif; AL-Thabaiti, Shaeel Ahmed; El-Mossalamy, E.H.; Hussain, Javed Ijaz; Khan, Zaheer

    2013-03-15

    Highlights: ► Stoichiometric ratio of S{sub 2}O{sub 3}{sup 2−} and Ag{sup +} ions are responsible to the formation of prefect transparent yellow colored silver sol. ► Higher S{sub 2}O{sub 3}{sup 2−} concentrations has damping effect. ► Head group of the surfactants and nature of the electrolytes have significant effect on the stability of silver nanoparticles. - Abstract: The impact of electrolytes, stabilizing and/or capping agents on morphology of colloidal silver nano-materials (AgNPs) has been studied spectroscopically. Sodium thiosulfate acts as reducing-, stabilizing- and damping-agents. Stoichiometric ratios of S{sub 2}O{sub 3}{sup 2−} and Ag{sup +} ions were responsible to the formation stable and prefect transparent dark yellow colored AgNPs. The S{sub 2}O{sub 3}{sup 2−}-stabilized AgNPs were significantly more stable in inorganic electrolytes (NaNO{sub 3}, Na{sub 2}SO{sub 4}, Na{sub 2}CO{sub 3} and KBr). S{sub 2}O{sub 3}{sup 2−} is adsorbed more strongly than the used other anions. The addition of cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulfate (SDS) has significant effects on the absorbance of S{sub 2}O{sub 3}{sup 2−}-stabilized AgNPs which can be rationalized in terms of electrostatic attraction and repulsion between the adsorbed S{sub 2}O{sub 3}{sup 2−} ions on to the surface of AgNPs and cationic and/or anionic head groups of used surfactants, respectively. Transmission electron microscopy images suggest that AgNPs are polydispersed, spherical and exhibiting an interesting irregular morphology.

  14. Electrical and morphological properties of magnetocaloric nano ZnNi ferrite

    NASA Astrophysics Data System (ADS)

    Hemeda, O. M.; Mostafa, Nasser Y.; Abd Elkader, Omar H.; Hemeda, D. M.; Tawfik, A.; Mostafa, M.

    2015-11-01

    A series of Zn1-xNixFe2O4 nano ferrite (with x=0, 0.2, 0.4, 0.6, 0.8, and 1) compositions were synthesized using the combustion technique. The powder samples were characterized by XRD. The X-ray analysis showed that the samples were single phase spinel cubic structure. The AC resistivity decreases by increasing the frequency from 1 kHz to 10 kHz. As the frequency of the applied field increases the hopping of charge carrier also increase, thereby decreasing the resistivity. A shift in dielectric maximum is observed toward higher temperature with increasing the Ni content from 536 K to 560 K at 1 kHz. The HRTEM (high resolution TEM) images of four compositions have lattice spacing which confirms the crystalline nature of the samples. The surface morphology SEM of the sample consists of some grains with relatively homogenies distribution with an average size varying from 0.85 to 0.92 μm. The values for entropy change in this work are still small but are significally higher than the values that have been reported for iron oxide nanoparticle. The magnetic entropy change was calculated from measurements of M (H, T) where H is the magnetic field and T is the temperature. The maximum value of entropy change (∆S) obtained near Curie temperature which makes these material candidates for magnetocaloric applications.

  15. A simple and efficient frit preparation method for one-end tapered-fused silica-packed capillary columns in nano-LC-ESI MS.

    PubMed

    Tan, Feng; Chen, Shuo; Zhang, Yangjun; Cai, Yun; Qian, Xiaohong

    2010-04-01

    A novel frit preparation method for one-end tapered-fused silica-packed capillary columns in nano-LC-ESI MS was developed. A hollow-fused silica capillary column with a tapered tip as nano-spray emitter was filled with 5 microm C(18) beads, and then a sintered frit about 0.25 mm in length was prepared at the tip by butane flame. A stainless steel protection tube with 0.5 mm id was used to control the length of the frit and to protect the packed C(18) beads behind the sintered frit during the sintering. C(18) sintered frits were evaluated by BSA tryptic digests with nano-LC-LTQ. The sintered frits did not produce post-column band broadening due to very small volume (about 0.2 nL) and did not produce adsorption to sample. The sintered frit columns had good separation reproducibility and separation performance compared with self-assembled particles frit columns and commercial columns. PMID:20162556

  16. Effects of the size of nano-copper catalysts and reaction temperature on the morphology of carbon fibers

    SciTech Connect

    Zhang Qian; Yu Liyan; Cui Zuolin

    2008-03-04

    In this study, carbon fibers with different morphologies, including coiled carbon nanofibers and straight carbon fibers, were obtained by the chemical vapor deposition using a Cu-catalytic pyrolysis of acetylene at 250 deg. C. The influences of nano-copper catalyst particle size and the reaction temperature on the morphology of carbon fibers were investigated. Under the same reaction condition, coiled carbon nanofibers generally were synthesized using nano-copper catalyst with smaller particles size, and bigger copper particles are apt to produce straight carbon fibers. With decreasing of reaction temperature to 200 deg. C, straight carbon fibers were obtained, instead of coiled carbon nanofibers at 250 deg. C. The product was characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD)

  17. Effect of hydroxyapatite nano-particles on morphology, rheology and thermal behavior of poly(caprolactone)/chitosan blends.

    PubMed

    Ghorbani, Fereshte Mohammad; Kaffashi, Babak; Shokrollahi, Parvin; Akhlaghi, Shahin; Hedenqvist, Mikael S

    2016-02-01

    The effect of hydroxyapatite nano-particles (nHA) on morphology, and rheological and thermal properties of PCL/chitosan blends was investigated. The tendency of nHA to reside in the submicron-dispersed chitosan phase is determined using SEM and AFM images. The presence of electrostatic interaction between amide sites of chitosan and ionic groups on the nHA surface was proved by FTIR. It is shown that the chitosan phase is thermodynamically more favorable for the nano-particles to reside than the PCL phase. Lack of implementation of Cox-Merz theory for this system shows that the polymer-nano-particle network is destructed by the flow. Results from dynamic rheological measurements and Zener fractional model show that the presence of nHA increases the shear moduli and relaxation time of the PCL/chitosan blends. DSC measurements showed that nHA nano-particles are responsible for the increase in melting and crystallization characteristics of the PCL/chitosan blends. Based on thermogravimetric analysis, the PCL/chitosan/nHA nano-composites exhibited a greater thermal stability compared to the nHA-free blends. PMID:26652456

  18. Adsorption and desorption characteristics of DNA onto the surface of amino functional mesoporous silica with various particle morphologies.

    PubMed

    Hikosaka, Ryouichi; Nagata, Fukue; Tomita, Masahiro; Kato, Katsuya

    2016-04-01

    Recently, deoxyribonucleic acid (DNA) adsorption on solid materials has been reported for applications such as genetic diagnosis of diseases, gene delivery, and biosensors. Mesoporous silica (MPS) is an excellent carrier because of its high surface area and large pore volume. Functionalization of the MPS surface can be controlled by silane coupling reagents, and the MPS particle morphology can be easily changed by the synthetic conditions. In this study, to evaluate the ability of DNA adsorption on MPS, the MPS surface was functionalized using four reagents, 3-aminopropyltriethoxysilane (-NH2), N-(2-aminoethyl)-3-aminopropyltriethoxysilane (-2ENH2), N-(6-aminohexyl)aminopropyltrimethoxysilane (-2HNH2), and (3-trimethoxysilylpropyl)diethylenetriamine (-3NH2), each having a different number of amino groups and alkyl chain lengths. Moreover, we prepared three types of MPSs with different particle morphologies: sheet-type structure (MPS sheet), spherical MPS (MCM-41s), and nonporous spherical silica. A high adsorption capacity was observed in MPS sheets with -2HNH2 (sheet-2HNH2) and -3NH2 (sheet-3NH2), as well as MCM-41s with -3NH2 (41s-3NH2). The adsorption and desorption rates of DNA on these three MPSs were then examined and the best results were obtained with 41s-3NH2. These results demonstrate that the amino functionalized MPS materials are useful DNA adsorbents. PMID:26764114

  19. Effects of hierarchical micro/nano-topographies on the morphology, proliferation and differentiation of osteoblast-like cells.

    PubMed

    Huang, Qianli; Elkhooly, Tarek A; Liu, Xujie; Zhang, Ranran; Yang, Xing; Shen, Zhijian; Feng, Qingling

    2016-09-01

    Coating the surfaces of titanium-based implants with appropriate hierarchical micro/nano-topographies resembling the structure of natural bone significantly enhances their biological performance. However, the relationship between nanostructures surfaces and their effects on modulating cellular response is not clearly understood. Moreover, it is not clear whether the surface chemistry or topography is the main factor on modulating cellular behavior, because the commonly used surface modification techniques for titanium-based implants simultaneously modify surface topography and chemistry. The aim of this study is to investigate osteoblast-like cell adhesion, proliferation and differentiation on hierarchical micro/nano-topographies with similar surface chemistry but different nano-scale features. Micro-arc oxidation and post hydrothermal treatment were employed to fabricate micro/nano-topographies on titanium. According to the morphological features, they were classified as microcrater (micro-topography), nanoplate (hierarchical topography with nanoplates) and nanoleaf (hierarchical topography with nanoleaves). The response of osteoblast like cells (SaOS-2) was studied on each surface after sputtering with a thin layer of gold (Au) to minimize the influence of surface chemistry. The morphological evaluation after histochemical staining revealed that the adherent cells were polygonal-shaped on microcrater surface, roundish on nanoplate surface and elongated on nanoleaf surface. Additionally, compared to microcrater surface, nanoplate surface slowed down cell proliferation and exhibited no enhancement on cell differentiation. However, nanoleaf surface supported cell proliferation and promoted cell differentiation. The results indicate that tuning morphological features of nanostructures on micro-topography can serve as a promising strategy to specifically modulate cellular response, such as cell morphology, proliferation, differentiation and mineralization. PMID

  20. Effect of content of chiral selector and pore size of core-shell type silica support on the performance of amylose tris(3,5-dimethylphenylcarbamate)-based chiral stationary phases in nano-liquid chromatography and capillary electrochromatography.

    PubMed

    Rocchi, Silvia; Fanali, Salvatore; Farkas, Tivadar; Chankvetadze, Bezhan

    2014-10-10

    In this study the separation performance of various chiral stationary phases (CSPs) made of polysaccharide-based chiral selectors coated onto superficially porous (core-shell or fused-core) silica supports were evaluated. The CSPs obtained by coating of various amounts of chiral selector (1-5%) onto supports of various pore size (100 and 300 Å) were studied. Their evaluation was pursued in both chiral nano-liquid chromatography (nano-LC) and chiral capillary electrochromatography (CEC). Among the goals of this study was to re-examine our previous unexpected finding of better performance of superficially porous CSP under CEC conditions compared to nano-LC conditions for a new set of chiral compounds, as well as to study the effect of varying the chiral selector content and nominal pore size of supporting silica on the performance of core-shell silica-based polysaccharide-type CSPs. Based on the results of this study it can be seen that CSPs based on superficially porous silica can successfully be used for the separation of enantiomers in both nano-LC and CEC mode. Only a slight advantage of CEC over nano-LC mode was observed in this study from the viewpoint of plate numbers, especially at higher mobile phase flow rates. It must also be noted that the optimal theoretical plate height is still too high and further optimization of superficially porous CSPs is necessary for both nano-LC and CEC applications. PMID:24908153

  1. Fabrication of Functional Nano-objects through RAFT Dispersion Polymerization and Influences of Morphology on Drug Delivery.

    PubMed

    Qiu, Liang; Xu, Chao-Ran; Zhong, Feng; Hong, Chun-Yan; Pan, Cai-Yuan

    2016-07-20

    To study the influence of self-assembled morphologies on drug delivery, four different nano-objects, spheres, nanorods, nanowires, and vesicles having aldehdye-based polymer as core, were successfully prepared via alcoholic RAFT dispersion polymerization of p-(methacryloxyethoxy)benzaldehyde (MAEBA) using poly((N,N'-dimethylamino)ethyl methacrylate) (PDMAEMA) as a macro chain transfer agent (macro-CTA) for the first time. The morphologies and sizes of the four nano-objects were characterized by TEM and DLS, and the spheres with average diameter (D) of 70 nm, the nanorods with D of 19 nm and length of 140 nm, and the vesicles with D of 137 nm were used in the subsequent cellular internalization, in vitro release, and intracellular release of the drug. The anticancer drug doxorubicin (DOX) was conjugated onto the core polymers of nano-objects through condensation reaction between aldehyde groups of the PMAEBA with primary amine groups in the DOX. Because the aromatic imine is stable under neutral conditions, but is decomposed in a weakly acidic solution, in vitro release of the DOX from the DOX-loaded nano-objects was investigated in the different acidic solutions. All of the block copolymer nano-objects show very low cytotoxicity to HeLa cells up to the concentration of 1.2 mg/mL, but the DOX-loaded nano-objects reveal different cell viability and their IC50s increase as the following order: nanorods-DOX < vesicles-DOX < spheres-DOX. The IC50 of nanowires-DOX is the biggest among the four nano-objects owing to their too large size to be internalized. Endocytosis tests demonstrate that the internalization of vesicles-DOX by the HeLa cells is faster than that of the nanorods-DOX, and the spheres-DOX are the slowest to internalize among the studied nano-objects. Relatively more nanorods localized in the acidic organelles of the HeLa cells lead to faster intracellular release of the DOX, so the IC50 of nanorods is lower than that of the vesicles-DOX. PMID:27399846

  2. Enhanced luminescence and degradation resistance in Tb modified Yttrium Borate core-nano silica shell phosphor under UV and VUV excitation

    NASA Astrophysics Data System (ADS)

    Chawla, Santa; Ravishanker; Khan, A. F.; Yadav, Ashish; Chander, H.; Shanker, V.

    2011-06-01

    Composition variation in optimized solid state reaction conditions has been done to achieve intense green emission in YTb xBO 3 phosphor under UV and VUV (147 nm resonant Xe*, 172 nm Xe 2* excimer band) excitation. Inert interface layer created by fabricating a shell of silica nanoparticles over individual phosphor grain protected the phosphor surface from deterioration and oxidation of luminescent ion (Tb 3+) thus completely arresting phosphor degradation. At optimum Tb content of 20 mol%, integrated photoluminescence intensity of developed YTb xBO 3 phosphor is four times higher than commercial green YBT. With short decay time of 4 ms, YTb xBO 3 core-nano silica shell green emitting phosphor has great application potential in PDP panel and phosphor coated Xe lamps.

  3. Mesoporous silica nanoparticles with controllable morphology prepared from oil-in-water emulsions.

    PubMed

    Gustafsson, Hanna; Isaksson, Simon; Altskär, Annika; Holmberg, Krister

    2016-04-01

    Mesoporous silica nanoparticles are an important class of materials with a wide range of applications. This paper presents a simple protocol for synthesis of particles as small as 40nm and with a pore size that can be as large as 9nm. Reaction conditions including type of surfactant, type of catalyst and presence of organic polymer were investigated in order to optimize the synthesis. An important aim of the work was to understand the mechanism behind the formation of these unusual structures and an explanation based on silica condensation in the small aqueous microemulsion droplets that are present inside the drops of an oil-in-water emulsion is put forward. PMID:26803604

  4. Combined exposure to nano-silica and lead induced potentiation of oxidative stress and DNA damage in human lung epithelial cells.

    PubMed

    Lu, Chun-Feng; Yuan, Xiao-Yan; Li, Li-Zhong; Zhou, Wei; Zhao, Jun; Wang, Yi-Mei; Peng, Shuang-Qing

    2015-12-01

    Growing evidence has confirmed that exposure to ambient particulate matters (PM) is associated with increased morbidity and mortality of cardiovascular and pulmonary diseases. Ambient PM is a complex mixture of particles and air pollutants. Harmful effects of PM are specifically associated with ultrafine particles (UFPs) that can adsorb high concentrations of toxic air pollutants and are easily inhaled into the lungs. However, combined effects of UFPs and air pollutants on human health remain unclear. In the present study, we elucidated the combined toxicity of silica nanoparticles (nano-SiO2), a typical UFP, and lead acetate (Pb), a typical air pollutant. Lung adenocarcinoma A549 cells were exposed to nano-SiO2 and Pb alone or their combination, and their combined toxicity was investigated by focusing on cellular oxidative stress and DNA damage. Factorial analyses were performed to determine the potential interactions between nano-SiO2 and Pb. Our results showed that exposure of A549 cells to a modest cytotoxic concentration of Pb alone induced oxidative stress, as evidenced by elevated reactive oxygen species generation and lipid peroxidation, and reduced glutathione content and superoxide dismutase and glutathione peroxidase activities. In addition, exposure of A549 cells to Pb alone induced DNA damage, as evaluated by alkaline comet assay. Exposure of A549 cells to non-cytotoxic concentration of nano-SiO2 did not induce cellular oxidative stress and DNA damage. However, exposure to the combination of nano-SiO2 and Pb potentiated oxidative stress and DNA damage in A549 cells. Factorial analyses indicated that the potentiation of combined toxicity of nano-SiO2 and Pb was induced by additive or synergistic interactions. PMID:26432026

  5. The Effect of HF/NH4F Etching on the Morphology of Surface Fractures on Fused Silica

    SciTech Connect

    Wong, L; Suratwala, T; Feit, M D; Miller, P E; Steele, R A

    2008-04-03

    The effects of HF/NH{sub 4}F, wet chemical etching on the morphology of individual surface fractures (indentations, scratches) and of an ensemble of surface fractures (ground surfaces) on fused silica glass has been characterized. For the individual surface fractures, a series of static or dynamic (sliding) Vickers and Brinnell indenters were used to create radial, lateral, Hertzian cone and trailing indentation fractures on a set of polished fused silica substrates which were subsequently etched. After short etch times, the visibility of both surface and subsurface cracks is significantly enhanced when observed by optical microscopy. This is attributed to the removal of the polishing-induced Bielby layer and the increased width of the cracks following etching allowing for greater optical scatter at the fracture interface. The removal of material during etching was found to be isotropic except in areas where the etchant has difficulty penetrating or in areas that exhibit significant plastic deformation/densification. Isolated fractures continue to etch, but will never be completely removed since the bottom and top of the crack both etch at the same rate. The etching behavior of ensembles of closely spaced cracks, such as those produced during grinding, has also been characterized. This was done using a second set of fused silica samples that were ground using either fixed or loose abrasives. The resulting samples were etched and both the etch rate and the morphology of the surfaces were monitored as a function of time. Etching results in the formation of a series of open cracks or cusps, each corresponding to the individual fractures originally on the surface of the substrate. During extended etching, the individual cusps coalesce with one another, providing a means of reducing the depth of subsurface damage and the peak-to-valley roughness. In addition, the material removal rate of the ground surfaces was found to scale with the surface area of the cracks as a

  6. Cellulose-silica/gold nanomaterials for electronic applications.

    PubMed

    Kim, Gwang-Hoon; Ramesh, Sivalingam; Kim, Joo-Hyung; Jung, Dongsoo; Kim, Heung Soo

    2014-10-01

    Cellulose and one dimensional nano-material composite has been investigated for various industrial applications due to their optical, mechanical and electrical properties. In present investigation, cellulose/silica and silica-gold hybrid biomaterials were prepared by sol-gel covalent cross-linking process. The tetraethoxysiliane (TEOS) and gold precursors and γ-aminopropyltriethoxysilane (γ-APTES) as coupling agent were used for sol-gel cross-linking process. The chemical and morphological properties of cellulose/silica and cellulose/silica-gold nano-materials via covalent cross-linking hybrids were confirmed by FTIR, XRD, SEM, and TEM analysis. In the sol-gel process, the inorganic particles were dispersed in the cellulose host matrix at the nanometer scale, bonding to the cellulose through the covalent bonds. PMID:25942815

  7. Influence of vacuum on nanosecond laser-induced surface damage morphology in fused silica at 1064 nm

    NASA Astrophysics Data System (ADS)

    Diaz, R.; Chambonneau, M.; Grua, P.; Rullier, J.-L.; Natoli, J.-Y.; Lamaignère, L.

    2016-01-01

    The influence of vacuum on nanosecond laser-induced damage at the exit surface of fused silica components is investigated at 1064 nm. In the present study, as previously observed in air, ring patterns surrounding laser-induced damage sites are systematically observed on a plane surface when initiated by multiple longitudinal modes laser pulses. Compared to air, the printed pattern is clearly more concentrated. The obtained correlation between the damage morphology and the temporal structure of the pulses suggests a laser-driven ablation mechanism resulting in a thorough imprint of energy deposit. The ablation process is assumed to be subsequent to an activation of the surface by hot electrons related to the diffusive expansion of a plasma formed from silica. This interpretation is strongly reinforced with additional experiments performed on an optical grating in vacuum on which damage sites do not show any ring pattern. Qualitatively, in vacuum, the intensity-dependent ring appearance speed V ∝ I1/2 is shown to be different than in air where V ∝ I1/3. This demonstrates that the mechanisms of formation of ring patterns are different in vacuum than in air. Moreover, the mechanism responsible of the propagation of the activation front in vacuum is shown to be outdone when experiments are performed in air.

  8. Morphologies of Phenytoin Crystals at Silica Model Surfaces: Vapor Annealing versus Drop Casting

    PubMed Central

    2014-01-01

    The controlled preparation of different crystal morphologies with varying preferential orientation with respect to the substrate is of crucial importance in many fields of applications. In this work, the controlled preparation of different phenytoin morphologies and the dependency of the preferential orientation of those crystallites is related with the preparation method (solvent annealing vs drop casting), as well as the physical–chemical interaction with the solvents in use. While solvent annealing induces the formation of particular structures that are partially dewetted, the drop casting technique from various solvent results in the formation of needle-like and elongated structures, with each having a distinct morphology. The morphologies are explained via the Hansen solubility parameters and correlated with the solvent vapor pressures. X-ray diffraction experiments reveal preferential orientations with respect to the solid substrate and indicate the surface-mediated stabilization of an unknown polymorph of phenytoin with an elongated unit cell in the b-axis. PMID:24966892

  9. Use of a Novel Sub-2 µm Silica Hydride Vancomycin Stationary Phase in Nano-Liquid Chromatography. II. Separation of Derivatized Amino Acid Enantiomers.

    PubMed

    Rocchi, Silvia; Fanali, Chiara; Fanali, Salvatore

    2015-11-01

    A novel vancomycin silica hydride stationary phase was synthesized and the particles of 1.8 µm were packed into fused silica capillaries of 75 µm internal diameter (I.D.). The chiral stationary phase (CSP) was tested for the separation of some derivatized amino acid enantiomers by using nano-liquid chromatography (nano-LC). Some experimental parameters such as the type and the content of organic modifier, the pH, and the concentration of the buffer added to the mobile phase were modified and the effect on enantioselectivity, retention time, and enantioresolution factor was studied. The separation of selected dansyl amino acids (Dns-AAs), e.g., Asp, Glu, Leu, and Phe in their enantiomers was initially achieved utilizing a mobile phase containing 85% (v/v) methanol (MeOH) and formate buffer measuring the enantioresolution factor and enantioselectivity in the range 1.74-4.17 and 1.39-1.59, respectively. Better results were obtained employing a more polar organic solvent as acetonitrile (ACN) in the mobile phase. Optimum results (Rs 1.41-6.09 and α 1.28-2.36) were obtained using a mobile phase containing formate buffer pH 2.5/water/MeOH/ACN 6:19:12.5:62.5 (v/v/v/v) in isocratic elution mode at flow rate of 130 nL/min. PMID:26335144

  10. Immobilized β-cyclodextrin-based silica vs polymer monoliths for chiral nano liquid chromatographic separation of racemates.

    PubMed

    Ghanem, Ashraf; Ahmed, Marwa; Ishii, Hideaki; Ikegami, Tohru

    2015-01-01

    The enantioselectivity of immobilized β-cyclodextrin phenyl carbamate-based silica monolithic capillary columns was compared to our previously described polymer counterpart. 2,3,6-Tris(phenylcarbamoyl)-β-cyclodextrin-6-methacrylate was used as a functional monomer for the preparation of β-cyclodextrin (β-CD)-based silica and polymer monoliths. The silica monoliths were prepared via the sol-gel technique in fused silica capillary followed by modification of the bare silica monoliths with an anchor group prior to polymerization with β-CD methacrylate using either 2,2'-azobis(isobutyronitrile) or benzoylperoxide as radical initiators. On the other hand, the polymer monoliths were prepared via the copolymerization of β-CD methacrylate and ethylene glycol dimethacrylate in different ratios in situ in fused silica capillary. The prepared silica/polymer monoliths were investigated for the chiral separation of different classes of pharmaceuticals namely; α- and β-blockers, anti-inflammatory drugs, antifungal drugs, dopamine antagonists, norepinephrine-dopamine reuptake inhibitors, catecholamines, sedative hypnotics, diuretics, antihistaminics, anticancer drugs and antiarrhythmic drugs. Baseline separation was achieved for alprenolol, bufuralol, carbuterol, cizolertine, desmethylcizolertine, eticlopride, ifosfamide, 1-indanol, propranolol, tebuconazole, tertatolol and o-methoxymandelic acid under reversed phase conditions using mobile phase composed of methanol and water. The silica-based monoliths showed a comparative enantioselectivity to the polymer monoliths. PMID:25476312

  11. The Evaluation of Surface Morphology Using Flexure Guided Nano-Positioning System and Ultra-Precision Lathe

    NASA Astrophysics Data System (ADS)

    Kwak, Nam-Su; Kim, Jae-Yeol

    In this study, piezoelectric actuator, Flexure guide, Power transmission element and control method and considered for Nano-positioning system apparatus. The main objectives of this thesis were to develop the 3-axis Ultra-precision stages which enable the 3-axis control by the manipulation of the piezoelectric actuator and to enhance the precision of the Ultra-Precision CNC lathe which is responsible for the ductile mode machining of the hardened-brittle material where the machining is based on the single crystal diamond. Ultra-precision CNC lathe is used for machining and motion error of the machine are compensated by using 3-axis Ultra-precision stage. Through the simulation and experiments on ultra-precision positioning, stability and priority on Nano-positioning system with 3-axis ultra-precision stage and control algorithm are secured by using NI Labview. And after applying the system, is to analyze the surface morphology of the mold steel (SKD61)

  12. Effect of morphology of dispersed nano-CeO2 on far infrared emission property of natural tourmaline.

    PubMed

    Zhu, Dongbin; Xu, Anping; Liang, Jinsheng

    2011-11-01

    Dispersed nano-CeO2 successfully grew on the surface of natural tourmaline powders by a precipitation method. The results of Fourier transform infrared spectroscopy (FTIR) showed that CeO2 (111) nanospots could apparently enhance the far infrared emission property of tourmaline in relation to CeO2 nanoparticles. This is the first report regarding the effect of the morphology of nano-CeO2 on the far infrared emission property of natural tourmaline. The results of the characterization by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) showed that CeO2 (111) nanospots have much more chemisorbed oxygen than CeO2 nanoparticles, which is beneficial to the unit cell volume shrinkage of tourmaline, thus increasing its far infrared emissivity. PMID:22413254

  13. Surface analysis and anti-graffiti behavior of a weathered polyurethane-based coating embedded with hydrophobic nano silica

    NASA Astrophysics Data System (ADS)

    Rabea, A. Mohammad; Mohseni, M.; Mirabedini, S. M.; Tabatabaei, M. Hashemi

    2012-03-01

    In this study, a permanent anti-graffiti polyurethane coating was prepared using concomitant loading of an OH-functional silicone modified polyacrylate additive ranging from 2 to 15 mol% and hydrophobic silica nanoparticles from 1 to 5 wt%. UV-visible spectroscopy, contact angle measurement and dynamic mechanical thermal analysis (DMTA) analysis were conducted on selected samples to study the weathering performance of samples containing various amounts of silica nanoparticles before and after accelerated weathering conditions. The results showed that higher amounts of additive had inferior effects on the anti-graffiti performance of the coating samples after exposure. However, silica nanoparticles could positively affect the anti-graffiti performance against ageing cycles. This improvement was attributed to lower degradation of samples containing silica nanoparticles and barrier property of nanoparticles against graffiti penetration. The presence of silica nanoparticles did not have any significant effect on the surface free energy of the samples prior and after ageing.

  14. Synthesis and Characterization of Ordered Mesoporous Silica with Controlled Macroscopic Morphology for Membrane Applications

    NASA Astrophysics Data System (ADS)

    Stohlman, Olive R.

    2011-12-01

    Ordered mesoporous materials have tunable pore sizes between 2 and 50 nm and are characterized by ordered pore structures and high surface areas (~1000 m2/g). This makes them particularly favorable for a number of membrane applications such as protein separation, polymer extrusion, nanowire fabrication and membrane reactors. These membranes can be fabricated as top-layers on macroporous supports or as embedded membranes in a dense matrix. The first part of the work deals with the hydrothermal synthesis and water-vapor/oxygen separation properties of supported MCM-48 and a new Al-MCM-48 type membrane for potential use in air conditioning systems. Knudsen-type permeation is observed in these membranes. The combined effect of capillary condensation and the aluminosilicate matrix resulted in the highest separation factor (142) in Al-MCM-48 membranes, with a water vapor permeance of 6x10 -8mol/m2·Pa·s. The second part focuses on synthesis of embedded mesoporous silica membranes with helically ordered pores by a novel Counter Diffusion Self-Assembly (CDSA) method. This method is an extension of the interfacial synthesis method for fiber synthesis using tetrabutylorthosilicate (TBOS) and cetyltrimethylammonium bromide (CTAB) as the silica source and surfactant respectively. The initial part of this study determined the effect of TBOS height and humidity on fiber formation. From this study, the range of TBOS heights for best microscopic and macroscopic ordering were established. Next, the CDSA method was used to successfully synthesize membranes, which were characterized to have good support plugging and an ordered pore structure. Factors that influence membrane synthesis and plug microstructure were determined. SEM studies revealed the presence of gaps between the plugs and support pores, which occur due to shrinking of the plug on drying. Development of a novel liquid deposition method to seal these defects constituted the last part of this work. Post sealing, excess

  15. Silica Supported Ceria Nanoparticles: A Hybrid Nanostructure To Increase Stability And Surface Reactivity Of Nano-crystalline Ceria

    SciTech Connect

    Munusamy, Prabhakaran; Sanghavi, Shail P.; Varga, Tamas; Thevuthasan, Suntharampillai

    2014-01-21

    The mixed oxidation state (3+/4+) of ceria nanoparticles of smaller sizes make them attractive materials for their catalytic antioxidant biological properties. However the unmodified smaller ceria nanoparticles are limited in their use due to particles agglomeration and reduced surface chemical reactivity in the solutions used to disperse the nanoparticles. This work describes an effort to stabilize small ceria nanoparticles, retaining their desired activity, on a larger stable silica support. The ceria nanoparticles attached to silica was synthesized by a solution synthesis technique in which the surface functional groups of silica nanoparticles were found to be essential for the formation of smaller ceria nanoparticles. The surface chemical and vibrational spectroscopy analysis revealed cerium–silicate (Ce-O-Si) covalent bond linkage between silica and cerium oxide nanoparticles. The colloidal properties (agglomerate particle size and suspension stability) of ceria attached to silica was significantly improved due to inherent physico-chemical characteristics of silica against random collision and gravitation settling as opposed to unmodified ceria nanoparticles in solution. The bio-catalytic activity of ceria nanoparticles in the 3+ oxidation state was not found to be limited by attachment to the silica support as measured by free radical scavenging activity in different biological media conditions.

  16. Morphological and cytohistochemical evaluation of renal effects of cadmium-doped silica nanoparticles given intratracheally to rat

    NASA Astrophysics Data System (ADS)

    Coccini, T.; Roda, E.; Barni, S.; Manzo, L.

    2013-04-01

    Renal morphological parameters were determined in rats intratracheally instilled with model cadmium-containing silica nanoparticles (Cd-SiNPs, 1mg/rat), also exploring whether their potential modifications would be associated with toxicogenomic changes. Cd-SiNP effects, evaluated 7 and 30 days post-exposure, were assessed by (i) histopathology (Haematoxylin/Eosin Staining), (ii) characterization of apoptotic features by TUNEL staining. Data were compared with those obtained by CdCl2 (400μg/rat), SiNPs (600μg/rat), 0.1 ml saline. Area-specific cell apoptosis was observed in all treatment groups: cortex and inner medulla were the most affected regions. Apoptotic changes were apparent at 7 days post-exposure in both areas, and were still observable in inner medulla 30 days after treatment. Increase in apoptotic frequency was more pronounced in Cd-SiNP-treated animals compared to either CdCl2 or SiNPs. Histological findings showed comparable alterations in the renal glomerular (cortex) architecture occurring in all treatment groups at both time-points considered. The glomeruli appeared often collapsed, showing condensed, packed mesangial and endothelial cells. Oedematous haemorrhagic glomeruli were also observed in Cd-SiNPs-treated animals. Bare SiNPs caused morphological and apoptotic changes without modifying the renal gene expression profile. These findings support the concept that multiple assays and an integrated testing strategy should be recommended to characterize toxicological responses to nanoparticles in mammalian systems.

  17. Silica-coated upconversion lanthanide nanoparticles: The effect of crystal design on morphology, structure and optical properties

    PubMed Central

    Kostiv, Uliana; Šlouf, Miroslav; Macková, Hana; Zhigunov, Alexander; Engstová, Hana; Smolková, Katarína; Ježek, Petr

    2015-01-01

    Summary NaYF4:Yb3+/Er3+ nanoparticles were synthesized by thermal decomposition of lanthanide trifluoroacetates using oleylamine (OM) as both solvent and surface binding ligand. The effect of reaction temperature and time on the properties of the particles was investigated. The nanoparticles were characterized by transmission electron microscopy (TEM), electron diffraction (ED), energy dispersive spectroscopy (EDX), dynamic light scattering (DLS), thermogravimetric analysis (TGA), elemental analysis and X-ray diffraction (XRD) to determine morphology, size, polydispersity, crystal structure and elemental composition of the nanocrystals. TEM microscopy revealed that the morphology of the nanoparticles could be fine-tuned by modifying of the synthetic conditions. A cubic-to-hexagonal phase transition of the NaYF4:Yb3+/Er3+ nanoparticles at temperatures above 300 °C was confirmed by both ED and XRD. Upconversion luminescence under excitation at 980 nm was observed in the luminescence spectra of OM–NaYF4:Yb3+/Er3+ nanoparticles. Finally, the OM–NaYF4:Yb3+/Er3+ nanoparticles were coated with a silica shell to enable further functionalization and increase biocompatibility and stability in aqueous media, preventing particle aggregation. PMID:26734520

  18. 'Nano' Morphology and Element Signatures of Early Life on Earth: A New Tool for Assessing Biogenicity

    NASA Technical Reports Server (NTRS)

    Oehler, D. Z.; Mostefaoui, S.; Meibom, A.; Selo, M.; McKay, D. S.; Robert, F.

    2006-01-01

    The relatively young technology of NanoSIMS is unlocking an exciting new level of information from organic matter in ancient sediments. We are using this technique to characterize Proterozoic organic material that is clearly biogenic as a guide for interpreting controversial organic structures in either terrestrial or extraterrestrial samples. NanoSIMS is secondary ion mass spectrometry for trace element and isotope analysis at sub-micron resolution. In 2005, Robert et al. [1] combined NanoSIMS element maps with optical microscopic imagery in an effort to develop a new method for assessing biogenicity of Precambrian structures. The ability of NanoSIMS to map simultaneously the distribution of organic elements with a 50 nm spatial resolution provides new biologic markers that could help define the timing of life s development on Earth. The current study corroborates the work of Robert et al. and builds on their study by using NanoSIMS to map C, N (as CN), S, Si and O of both excellently preserved microfossils and less well preserved, non-descript organics in Proterozoic chert from the ca. 0.8 Ga Bitter Springs Formation of Australia.

  19. Mechanical and morphological properties of polypropylene/nano α-Al2O3 composites.

    PubMed

    Mirjalili, F; Chuah, L; Salahi, E

    2014-01-01

    A nanocomposite containing polypropylene (PP) and nano α-Al2O3 particles was prepared using a Haake internal mixer. Mechanical tests, such as tensile and flexural tests, showed that mechanical properties of the composite were enhanced by addition of nano α-Al2O3 particles and dispersant agent to the polymer. Tensile strength was approximately ∼ 16% higher than pure PP by increasing the nano α-Al2O3 loading from 1 to 4 wt% into the PP matrix. The results of flexural analysis indicated that the maximum values of flexural strength and flexural modulus for nanocomposite without dispersant were 50.5 and 1954 MPa and for nanocomposite with dispersant were 55.88 MPa and 2818 MPa, respectively. However, higher concentration of nano α-Al2O3 loading resulted in reduction of those mechanical properties that could be due to agglomeration of nano α-Al2O3 particles. Transmission and scanning electron microscopic observations of the nanocomposites also showed that fracture surface became rougher by increasing the content of filler loading from 1 to 4% wt. PMID:24688421

  20. Mechanical and Morphological Properties of Polypropylene/Nano α-Al2O3 Composites

    PubMed Central

    Mirjalili, F.; Chuah, L.; Salahi, E.

    2014-01-01

    A nanocomposite containing polypropylene (PP) and nano α-Al2O3 particles was prepared using a Haake internal mixer. Mechanical tests, such as tensile and flexural tests, showed that mechanical properties of the composite were enhanced by addition of nano α-Al2O3 particles and dispersant agent to the polymer. Tensile strength was approximately ∼16% higher than pure PP by increasing the nano α-Al2O3 loading from 1 to 4 wt% into the PP matrix. The results of flexural analysis indicated that the maximum values of flexural strength and flexural modulus for nanocomposite without dispersant were 50.5 and 1954 MPa and for nanocomposite with dispersant were 55.88 MPa and 2818 MPa, respectively. However, higher concentration of nano α-Al2O3 loading resulted in reduction of those mechanical properties that could be due to agglomeration of nano α-Al2O3 particles. Transmission and scanning electron microscopic observations of the nanocomposites also showed that fracture surface became rougher by increasing the content of filler loading from 1 to 4% wt. PMID:24688421

  1. Synthesis of silver nanoparticles deposited on silica by γ-irradiation and preparation of PE/Ag nano compound masterbatches

    NASA Astrophysics Data System (ADS)

    Nguyen, Thi Kim Lan; Trinh Nguyen, Thuy Ai; Phu Dang, Van; Duy Nguyen, Ngoc; Le, Anh Quoc; Hien Nguyen, Quoc

    2013-12-01

    Silver nanoparticles (AgNPs) deposited on silica were synthesized by gamma Co-60 irradiation of Ag+ dispersion in silica/ethanol/water mixture (9/80/20:w/v/v). The reduction of Ag+ is occurred by hydrated electron (e-aq) and hydrogen atom (H•) generated during radiolysis of ethanol/water. The conversion doses (Ag+ → Ag0) were determined by UV-Vis spectroscopy. The synthesized AgNPs/silica were characterized by transmission electron microscopy (TEM) and x-ray diffraction (XRD), which showed the size of AgNPs to be in the range of 5-40 nm for Ag+ concentrations from 5 to 20 mM. Masterbatches of PE/AgNPs/silica compound with silver content from 250 to 1000 mg kg-1 were also prepared. These masterbatches can be suitably used for various applications such as antimicrobial food containers and packing films, etc.

  2. Preparation of cellulose acetate nano-biocomposites using acidified gelatin-montmorillonite as nanofiller: Morphology and thermal properties

    NASA Astrophysics Data System (ADS)

    Ferfera-Harrar, Hafida; Dairi, Nassima

    2012-07-01

    Nano-biocomposites, based on natural polymer as matrix and layered silicates as inorganic nano-fillers, represent an emerging group of hybrid materials. Their advance has strong promise in designing eco-friendlynanocomposites with enhanced properties (mechanical, barrier, thermal…), at low filler levels, of great interest forseveral applications. Thus, this current contribution focuses on the development of Eco-friendly nanocomposites filmsbased on cellulose acetate (CA) and a novel organoclay, prepared from sodium montmorillonite and acidified gelatin asbio-modifier (MMT-AGe), using solution casting process. The effect of clay loading on morphology and properties ofbiomaterials was studied. The nano-hybrids materials elaborated at different clay content were characterized by Fourier Transform Infrared Spectroscopy (FTIR). The clay dispersion was investigated by X-Ray Diffraction (XRD). It wassuggested the formation of disordered intercalated structures or partially exfoliated/intercalated ones, with small claytactoïds remaining. Tg and Tm values, evaluated using Differential Scanning Calorimeter analysis (DSC), were slightlyaffected with addition of clay compared to neat CA, while significant improvement in thermal stability, was observed bymeans of thermogravimetric analysis (TGA), being the highest at 5 wt % clay loading. The unique properties of thesenano-biocomposites may result from the interactions developed between the groups of CA and bio-modified MMT.

  3. An investigation on morphology and mechanical properties of HDPE/nanoclay/nanoCaCO3 ternary nanocomposites

    NASA Astrophysics Data System (ADS)

    Garmabi, Hamid; Tabari, Seyed Emad Alavi; Javadi, Azizeh; Behrouzi, Hormoz; Hosseini, Gholamabbas

    2016-03-01

    Ternary Nanocomposites of high-density polyethylene (HDPE) containing two types of nano particles, a layered organoclay (Closite 15A) and a spherical nano Calcium Carbonate (CaCO3), with various compositions were prepared using melt mixing. Maleic anhydride grafted polyethylene (MA-g-PE) was used to enhance the dispersion of nanofillers and better interface adhesion. Three different levels of nanoclay (1, 3, 5 wt. %), CaCO3 (6, 8, 10 wt. %) and MA-g-PE (3, 6, 9 wt. %) were used. The mixing was done in two steps: First a concentrated masterbatch of nanoparticles in HPDE and MA-g-PE was prepared using an internal mixer and then melt-mixing of nanocomposites was done in a lab scale co-rotating twin screw extruder. The morphology of samples was studied using Scanning Electron Microscopy (SEM) and mechanical properties were evaluated using tensile and impact tests. According to the SEM micrographs, nanofillers were well dispersed in the HDPE matrix and XRD patterns showed the intercalation of nanoclay layers too. Generally using the layered nanoclay can enhance the tensile modulus while the use of spherical nano CaCO3 results into improved toughness. It was found that co-incorporation of these two types of nanofillers, leads to improve the stiffness and minimize the reduction of impact strength, simultaneously.

  4. Characterization of the Morphology and Rapid Expansion of Swellable Organically Modified Silica

    NASA Astrophysics Data System (ADS)

    Christman, Lilianna E.; Logue, Amanda; Edmiston, Paul L.; Lehman, Susan Y.

    2011-03-01

    Swellable organically modified silica (SOMS) is a novel sol-gel derived material.~ SOMS is hydrophobic and selectively absorbs non-polar liquids and immediately swells 5 to 6 times upon absorption.~ SOMS can be used to remove organic contaminants from water; the contaminant can then be recovered and the SOMS reused.~ We have investigated the SOMS swelling behavior of neat organic liquids usng macroscopic measurements of the force exerted during expansion and through atomic force microscopy (AFM) of the surface. ~A powdered SOMS sample was placed in a cylinder with an adjustable piston.~ Solvent percolated into the cylinder and the piston gradually moved to allow expansion while measuring the force using a load cell.~ During expansion the SOMS exerted forces up to 150 N per gram of material.~ AFM shows the surface of the SOMS is textured with cauliflower-like features.~ In unswollen SOMS, these globules have length scales of a few hundred nanometers, while for SOMS swollen in a solvent the features expand to several micrometers.

  5. Silica-Supported Titania-Zirconia Nanocomposites: Structural and Morphological Characteristics in Different Media

    NASA Astrophysics Data System (ADS)

    Sulym, Iryna; Goncharuk, Olena; Sternik, Dariusz; Skwarek, Ewa; Derylo-Marczewska, Anna; Janusz, Wladyslaw; Gun'ko, Vladimir M.

    2016-02-01

    A series of TiO2-ZrO2/SiO2 nanocomposites were synthesized using a liquid-phase method and characterized by various techniques, namely, nitrogen adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, high-resolution transmission electron microscopy, and photon correlation spectroscopy (PCS). It was revealed that the component ratio and calcination temperature affect the phase composition of nanocomposites. Composites TiZrSi1 (TiO2:ZrO2:SiO2 = 3:10:87) and TiZrSi2 (10:10:80) calcined at 1100 °C demonstrate the presence of t-ZrO2 crystallites in TiZrSi1 and ZrTiO4 phase in TiZrSi2. The samples calcined at 550 °C were amorphous as it was found from XRD data. According to the Raman spectra, the bands specific for anatase are observed in TiZrSi2. According to XPS data, Zr and Ti are in the highest oxidation state (+4). Textural analysis shows that initial silica is mainly meso/macroporous, but composites are mainly macroporous. The particle size distributions in aqueous media showed a tendency of increasing particle size with increasing TiO2 content in the composites.

  6. Silica-Supported Titania-Zirconia Nanocomposites: Structural and Morphological Characteristics in Different Media.

    PubMed

    Sulym, Iryna; Goncharuk, Olena; Sternik, Dariusz; Skwarek, Ewa; Derylo-Marczewska, Anna; Janusz, Wladyslaw; Gun'ko, Vladimir M

    2016-12-01

    A series of TiO2-ZrO2/SiO2 nanocomposites were synthesized using a liquid-phase method and characterized by various techniques, namely, nitrogen adsorption-desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, high-resolution transmission electron microscopy, and photon correlation spectroscopy (PCS). It was revealed that the component ratio and calcination temperature affect the phase composition of nanocomposites. Composites TiZrSi1 (TiO2:ZrO2:SiO2 = 3:10:87) and TiZrSi2 (10:10:80) calcined at 1100 °С demonstrate the presence of t-ZrO2 crystallites in TiZrSi1 and ZrTiO4 phase in TiZrSi2. The samples calcined at 550 °С were amorphous as it was found from XRD data. According to the Raman spectra, the bands specific for anatase are observed in TiZrSi2. According to XPS data, Zr and Ti are in the highest oxidation state (+4). Textural analysis shows that initial silica is mainly meso/macroporous, but composites are mainly macroporous. The particle size distributions in aqueous media showed a tendency of increasing particle size with increasing TiO2 content in the composites. PMID:26924815

  7. Silica and Iron Oxide Minerals in Acidic Hydrothermal Alteration Products at Volcanic Fumaroles - Crystallinity of Cristobalite and Morphology of Hematite

    NASA Astrophysics Data System (ADS)

    Isobe, H.; Korenaga, Y.

    2010-12-01

    Cristobalite is a common alteration product occured in highly acidic hydrothermal environment around fumaroles in geothermal/volcanic areas. In the terrestrial environment, iron mineral species and morphology in the alteration products relate to temperature, acidity and redox conditions of surface or subsurface fluids. These silica and iron minerals show various textures and crystallographic characteristics depending on geochemical conditions. Severe acidic hydrothermal alteration of the pyroxene-amphibole andesite occurs at Garan-dake volcano, Oita, Japan. We carried out petrologic observation and powder XRD analysis of the hydrothermal alteration products with various color, composition and textures. XRD analysis revealed that the alteration degree is represented by abundance of cristobalite. Intermediately altered layers are characterized by various occurrence of alunite, pyrite, kaolinite, goethite and hematite. Detailed powder XRD analysis show that the primary diffraction peak of cristobalite composed with two or three phases with different d-spacing and FWHM by peak profile fitting analysis. Most samples contain well-crystallized, shorter d-spacing and narrow FWHM cristobalite and less-crystallized, longer d-spacing and wide FWHM cristobalite with various ratio. Samples with silica phases resembled to agate, and reddish samples with spheroidal hematite of several micron meters in diameter contain the least-cryatallized, largest d-spacing and very wide FWHM cristobalite phase in addition to the well and low-crystallized phases. The granular hematite grains show quite similar texture with hydrothermal alteration experimental products of iron-rich basalt with sulfuric acid solution possible hydrothermal alteration in the Martian volcano. Occurence of poorly crystalline cristobalite and fine grained spheroidal hematite may have essential constraint to understand acidic hydrotermal alteration processes in the volcanic provinces on the terrestrial planets.

  8. Synthesis, morphology and antifungal activity of nano-particulated amphotericin-B, ketoconazole and thymoquinone against Candida albicans yeasts and Candida biofilm.

    PubMed

    Randhawa, Mohammad A; Gondal, Mohammed A; Al-Zahrani, Al-Hosain J; Rashid, Siddique G; Ali, Ashraf

    2015-01-01

    In the current study, nano-particulated drugs-Amphotericin-B, Ketoconazole and Thymoquinone (an active ingredient of Nigella sativa)-were prepared using the ball milling technique, and their particle sizes were examined by transmission electron microscopy (TEM) and using a particle size analyzer. The grain sizes of the prepared compounds were found in between 5 to 20 nm, and exhibited quasi-spherical morphology. The antifungal activity of each nano-particulated drug was investigated in vitro against Candida albicans yeasts and Candida biofilm, and compared with their micro-structured conventional forms. Nano-sized drugs were found to be two to four times more effective in disinfecting both the Candida yeasts and Candida biofilm. The study is a first of its kind as nano-forms of drugs have not been studied against Candida and Candida biofilm before. Further investigations are required for the determination of the clinical significance of the nano-formulation of antifungal substances. PMID:25560257

  9. One Polymorph and Various Morphologies of Phenytoin at a Silica Surface Due to Preparation Kinetics

    PubMed Central

    2014-01-01

    The preparation of solid crystalline films at surfaces is of great interest in a variety of fields. Within this work the preparation of pharmaceutically relevant thin films containing the active pharmaceutical ingredient phenytoin is demonstrated. The preparation techniques applied include drop casting, spin coating, and vacuum deposition. For the solution processed samples a decisive impact of the solution concentration and the applied film fabrication technique is observed; particular films form for all samples but with their extensions along different crystallographic directions strongly altered. Vacuum deposition of phenytoin reveals amorphous films, which over time crystallize into needle-like or particular-type structures whereby a nominal thickness of 50 nm is required to achieve a fully closed layer. Independent of all preparation techniques, the resulting polymorph is the same for each sample as confirmed by specular X-ray diffraction scans. Thus, morphologies observed via optical and atomic force microscope techniques are therefore a result of the preparation technique. This shows that the different time scales for which crystallization is obtained is the driving force for the various morphologies in phenytoin thin films rather than the presence of another polymorph forming. PMID:25593545

  10. The influence of nano silica particles on gamma-irradiation ageing of elastomers based on chlorosulphonated polyethylene and acrylonitrile butadiene rubber

    NASA Astrophysics Data System (ADS)

    Marković, G.; Marinović-Cincović, M.; Tanasić, Lj.; Jovanović, V.; Samaržija-Jovanović, S.; Vukić, N.; Budinski-Simendić, J.

    2011-12-01

    The goal of this work was to study gamma irradiation ageing of rubber blends based on acrylonitrile butadiene rubber (NBR) and chlorosulphonated polyethylene rubber (CSM) reinforced by silica nano particles. The NBR/CSM compounds (50: 50, w/w) filled with different content of filler (0-100 phr) were crosslinked by sulfur. The vulcanization characteristics were assessed using the rheometer with an oscillating disk. The vulcanizates were prepared in a hydraulic press. The obtained materials were exposed to the different irradiation doses (100, 200, 300 and 400 kGy). The mechanical properties (hardness, modulus at 100% elongation, tensile strength and elongation at break) and swelling numbers were assessed before and after gamma irradiation ageing.

  11. Photoinduced charge generation rates in soluble P3HT : PCBM nano-aggregates predict the solvent-dependent film morphology

    NASA Astrophysics Data System (ADS)

    Roy, Palas; Jha, Ajay; Dasgupta, Jyotishman

    2016-01-01

    The device efficiency of bulk heterojunction (BHJ) solar cells is critically dependent on the nano-morphology of the solution-processed polymer : fullerene blend. Active control on blend morphology can only emanate from a detailed understanding of solution structures during the film casting process. Here we use photoinduced charge transfer (CT) rates to probe the effective length scale of the pre-formed solution structures and their energy disorder arising from a mixture of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) in three different organic solvents. The observed solvent-dependent ultrafast biphasic rise of the transient polaron state in solution along with changes detected in the C&z.dbd;C stretching frequency of bound PCBM provides direct evidence for film-like P3HT : PCBM interfaces in solution. Using the diffusive component of the charge transfer rate, we deduce ~3-times larger functional nano-domain size in toluene than in chlorobenzene thereby correctly predicting the relative polymer nanofiber widths observed in annealed films. We thus provide first experimental evidence for the postulated polymer : fullerene : solvent ternary phase that seeds the eventual morphology in spin-cast films. Our work motivates the design of new chemical additives to tune the grain size of the evolving polymer : fullerene domains within the solution phase.The device efficiency of bulk heterojunction (BHJ) solar cells is critically dependent on the nano-morphology of the solution-processed polymer : fullerene blend. Active control on blend morphology can only emanate from a detailed understanding of solution structures during the film casting process. Here we use photoinduced charge transfer (CT) rates to probe the effective length scale of the pre-formed solution structures and their energy disorder arising from a mixture of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) in three

  12. Organization of research team for nano-associated safety assessment in effort to study nanotoxicology of zinc oxide and silica nanoparticles.

    PubMed

    Kim, Yu-Ri; Park, Sung Ha; Lee, Jong-Kwon; Jeong, Jayoung; Kim, Ja Hei; Meang, Eun-Ho; Yoon, Tae Hyun; Lim, Seok Tae; Oh, Jae-Min; An, Seong Soo A; Kim, Meyoung-Kon

    2014-01-01

    Currently, products made with nanomaterials are used widely, especially in biology, bio-technologies, and medical areas. However, limited investigations on potential toxicities of nanomaterials are available. Hence, diverse and systemic toxicological data with new methods for nanomaterials are needed. In order to investigate the nanotoxicology of nanoparticles (NPs), the Research Team for Nano-Associated Safety Assessment (RT-NASA) was organized in three parts and launched. Each part focused on different contents of research directions: investigators in part I were responsible for the efficient management and international cooperation on nano-safety studies; investigators in part II performed the toxicity evaluations on target organs such as assessment of genotoxicity, immunotoxicity, or skin penetration; and investigators in part III evaluated the toxicokinetics of NPs with newly developed techniques for toxicokinetic analyses and methods for estimating nanotoxicity. The RT-NASA study was carried out in six steps: need assessment, physicochemical property, toxicity evaluation, toxicokinetics, peer review, and risk communication. During the need assessment step, consumer responses were analyzed based on sex, age, education level, and household income. Different sizes of zinc oxide and silica NPs were purchased and coated with citrate, L-serine, and L-arginine in order to modify surface charges (eight different NPs), and each of the NPs were characterized by various techniques, for example, zeta potentials, scanning electron microscopy, and transmission electron microscopy. Evaluation of the "no observed adverse effect level" and systemic toxicities of all NPs were performed by thorough evaluation steps and the toxicokinetics step, which included in vivo studies with zinc oxide and silica NPs. A peer review committee was organized to evaluate and verify the reliability of toxicity tests, and the risk communication step was also needed to convey the current findings

  13. Organization of research team for nano-associated safety assessment in effort to study nanotoxicology of zinc oxide and silica nanoparticles

    PubMed Central

    Kim, Yu-Ri; Park, Sung Ha; Lee, Jong-Kwon; Jeong, Jayoung; Kim, Ja Hei; Meang, Eun-Ho; Yoon, Tae Hyun; Lim, Seok Tae; Oh, Jae-Min; An, Seong Soo A; Kim, Meyoung-Kon

    2014-01-01

    Currently, products made with nanomaterials are used widely, especially in biology, bio-technologies, and medical areas. However, limited investigations on potential toxicities of nanomaterials are available. Hence, diverse and systemic toxicological data with new methods for nanomaterials are needed. In order to investigate the nanotoxicology of nanoparticles (NPs), the Research Team for Nano-Associated Safety Assessment (RT-NASA) was organized in three parts and launched. Each part focused on different contents of research directions: investigators in part I were responsible for the efficient management and international cooperation on nano-safety studies; investigators in part II performed the toxicity evaluations on target organs such as assessment of genotoxicity, immunotoxicity, or skin penetration; and investigators in part III evaluated the toxicokinetics of NPs with newly developed techniques for toxicokinetic analyses and methods for estimating nanotoxicity. The RT-NASA study was carried out in six steps: need assessment, physicochemical property, toxicity evaluation, toxicokinetics, peer review, and risk communication. During the need assessment step, consumer responses were analyzed based on sex, age, education level, and household income. Different sizes of zinc oxide and silica NPs were purchased and coated with citrate, L-serine, and L-arginine in order to modify surface charges (eight different NPs), and each of the NPs were characterized by various techniques, for example, zeta potentials, scanning electron microscopy, and transmission electron microscopy. Evaluation of the “no observed adverse effect level” and systemic toxicities of all NPs were performed by thorough evaluation steps and the toxicokinetics step, which included in vivo studies with zinc oxide and silica NPs. A peer review committee was organized to evaluate and verify the reliability of toxicity tests, and the risk communication step was also needed to convey the current

  14. Modeling the influence of particle morphology on the fracture behavior of silica sand using a 3D discrete element method

    NASA Astrophysics Data System (ADS)

    Cil, Mehmet B.; Alshibli, Khalid A.

    2015-02-01

    The constitutive behavior and deformation characteristics of uncemented granular materials are to a large extent derived from the fabric or geometry of the particle structure and the interparticle friction resulting from normal forces acting on particles or groups of particles. Granular materials consist of discrete particles with a fabric (microstructure) that changes under loading. Synchrotron micro-computed tomography (SMT) has emerged as a powerful non-destructive 3D scanning technique to study geomaterials. In this paper, SMT was used to acquire in situ scans of the oedometry test of a column of three silica sand particles. The sand is known as ASTM 20-30 Ottawa sand, and has a grain size between US sieves #20 (0.841 mm) and #30 (0.595 mm). The characteristics and evolution of particle fracture in sand were examined using SMT images, and a 3D discrete element method (DEM) was used to model the fracture behavior of sand particles. It adopts the bonded particle model to generate a crushable agglomerate that consists of a large number of small spherical sub-particles. The agglomerate shape matches the 3D physical shape of the tested sand particles by mapping the particle morphology from the SMT images. The paper investigates and discusses the influence of agglomerate packing (i.e., the number and size distribution of spherical sub-particles that constitute the agglomerate) and agglomerate shape on the fracture behavior of crushable particles.

  15. Sintering Effects on Morphology, Thermal Stability and Surface Area of Sol-Gel Derived Nano-Hydroxyapatite Powder

    NASA Astrophysics Data System (ADS)

    Kapoor, Seema; Batra, Uma; Kohli, Suchita

    2011-12-01

    Hydroxyapatite (HAP) ceramics have been recognized as substitute materials for bone and teeth in orthopedic and dentistry field due to their chemical and biological similarity to human hard tissue. The nanosized and nanocrystalline forms of HAP have great potential to revolutionize the hard tissue-engineering field, starting from bone repair and augmentation to controlled drug delivery systems. This paper reports the synthesis of biomimetic nano-hydroxyapatite (HAP) by sol-gel method using calcium nitrate tetrahydrate (CNT) and potassium dihydrogen phosphate (KDP) as calcium and phosphorus precursors, respectively to obtain a desired Ca/P ratio of 1.67. Deionized water was used as a diluting media for HAP sol preparation and ammonia was used to adjust the pH to 11. After aging, the HAP gel was dried at 55 °C and sintered to different temperatures (200 °C, 400 °C, 600 °C, 800 °C, 1000 °C and 1200 °C). The dried and sintered powders were characterized for phase composition using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The particle size and morphology was studied using transmission electron microscopy (TEM). The thermal behavior of the dried HAP nanopowder was studied in the temperature range of 55 °C to 1000 °C using thermal gravimetric analyser (TGA). The BET surface area of absorbance was determined by Nitrogen adsorption using Brunauer-Emmett-Teller (BET) method. The presence of characteristic peaks of the phosphate and OH groups in FTIR spectrums confirmed the formation of pure HAP in dried as well as sintered powders. XRD results also confirmed the formation of stoichiometric nano-HAP. Sintering revealed that with increase in temperature, both the crystallinity and crystallite size of nano-HAP particles increased. The synthesized nano-HAP powder was found to be stable upto 1000 °C without any additional phase other than HAP, whereas peak of β-TCP (tricalcium phosphate) was observed at 1200 °C. Photomicrograph of

  16. Sintering Effects on Morphology, Thermal Stability and Surface Area of Sol-Gel Derived Nano-Hydroxyapatite Powder

    SciTech Connect

    Kapoor, Seema; Batra, Uma; Kohli, Suchita

    2011-12-12

    Hydroxyapatite (HAP) ceramics have been recognized as substitute materials for bone and teeth in orthopedic and dentistry field due to their chemical and biological similarity to human hard tissue. The nanosized and nanocrystalline forms of HAP have great potential to revolutionize the hard tissue-engineering field, starting from bone repair and augmentation to controlled drug delivery systems. This paper reports the synthesis of biomimetic nano-hydroxyapatite (HAP) by sol-gel method using calcium nitrate tetrahydrate (CNT) and potassium dihydrogen phosphate (KDP) as calcium and phosphorus precursors, respectively to obtain a desired Ca/P ratio of 1.67. Deionized water was used as a diluting media for HAP sol preparation and ammonia was used to adjust the pH to 11. After aging, the HAP gel was dried at 55 deg. C and sintered to different temperatures (200 deg. C, 400 deg. C, 600 deg. C, 800 deg. C, 1000 deg. C and 1200 deg. C). The dried and sintered powders were characterized for phase composition using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). The particle size and morphology was studied using transmission electron microscopy (TEM). The thermal behavior of the dried HAP nanopowder was studied in the temperature range of 55 deg. C to 1000 deg. C using thermal gravimetric analyser (TGA). The BET surface area of absorbance was determined by Nitrogen adsorption using Brunauer-Emmett-Teller (BET) method. The presence of characteristic peaks of the phosphate and OH groups in FTIR spectrums confirmed the formation of pure HAP in dried as well as sintered powders. XRD results also confirmed the formation of stoichiometric nano-HAP. Sintering revealed that with increase in temperature, both the crystallinity and crystallite size of nano-HAP particles increased. The synthesized nano-HAP powder was found to be stable upto 1000 deg. C without any additional phase other than HAP, whereas peak of {beta}-TCP (tricalcium phosphate) was observed

  17. Processing, morphology, and water uptake of Nafion/ex situ Stöber silica nanocomposite membranes as a function of particle size.

    PubMed

    Muriithi, Beatrice; Loy, Douglas A

    2012-12-01

    Because of the bicontinuous phase structure of Nafion with small hydrophilic channels, formation of composites with silica colloids to improve thermal stability, hydration, and proton conductivity should be influenced by size and surface functionality of the colloids. To test this hypothesis, we prepared batches of silica particles between 20 and 400 nm in diameter with narrow polydispersities using a modified Stöber procedure. Some particles were subsequently surface-modified using mercaptopropyltriethoxysilane. Enough particles were mixed with Nafion in alcohols to achieve 5 wt % silica in the final membranes, which were made by casting and drying. Membrane top and bottom surface and cross-section morphologies were examined with AFM and SEM to determine how the particles were dispersed. We discovered that casting the membranes from dispersions with viscosities less than 65 cPs led to larger particles floating to the top surface of the membrane where they were easily dislodged from the dry membrane. Membranes cast from more viscous solutions exhibited homogeneous distributions of particles. Water uptake was over 60% higher in nanocomposites with unmodified silica particles than for Nafion and about 15% higher than for Nafion with in situ generated silica particles, but showed no trend in water uptake correlating with particle size. Surface silated particles of all sizes appeared to have reduced water uptake relative to Nafion alone. PMID:23138476

  18. Synthesis of nano Cu2O on cotton: morphological, physical, biological and optical sensing characterizations.

    PubMed

    Sedighi, Ali; Montazer, Majid; Samadi, Nasrin

    2014-09-22

    In this paper, Cu2O nanoparticles were in situ synthesized on cotton fabric through a new simple and cost-effective chemical reduction method using copper sulfate, sodium hydroxide and ammonia. Cotton fabric participates as a reducing agent in reduction of copper sulfate and facilitates synthesis of cuprous oxide in nano-scale as a stabilizer. The produced cotton/nano Cu2O composite were characterized by X-ray diffraction, scanning electron microscopy and Energy-dispersive X-ray spectroscopy. Interaction of Cu2O with cotton fabric in addition to alteration of cotton functional groups were studied by Fourier transforms infrared spectroscopy. The intermediate solution, copper-amine complex, was analyzed by ultraviolet-visible spectroscopy. The mechanical properties of the cotton/nano Cu2O composite were studied using Instron indicated a higher tensile strain. The antibacterial activity of the fabric samples showed considerable behavior against S. aureus and E. coli. Further, the treated fabric became highly hydrophobic and sensed ammonia and hydrogen peroxide chromatically. PMID:24906783

  19. Double layer approach to create durable superhydrophobicity on cotton fabric using nano silica and auxiliary non fluorinated materials

    NASA Astrophysics Data System (ADS)

    Manatunga, Danushika Charyangi; de Silva, Rohini M.; de Silva, K. M. Nalin

    2016-01-01

    Creation of differential superhydrophobicity by applying different non-fluorinated hydrophobization agents on a cotton fabric roughened with silica nanoparticles was studied. Cotton fabric surface has been functionalized with silica nanoparticles and further hydrophobized with different hydrophobic agents such as hexadecyltrimethoxy silane (HDTMS), stearic acid (SA), triethoxyoctyl silane (OTES) and hybrid mixtures of HDTMS/SA and HDTMS/OTES. The cotton fabrics before and after the treatment were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM) and thermogravimetric analysis (TGA). The wetting behavior of cotton samples was investigated by water contact angle (WCA) measurement, water uptake, water repellency and soil repellency testing. The treated fabrics exhibited excellent water repellency and high water contact angles (WCA). When the mixture of two hydrophobization agents such as HDTMS/OTES and HDTMS/SA is used, the water contact angle has increased (145°-160°) compared to systems containing HDTMS, OTES, SA alone (130°-140°). It was also noted that this fabricated double layer (silica + hydrophobization agent) was robust even after applying harsh washing conditions and there is an excellent anti-soiling effect observed over different stains. Therefore superhydrophobic cotton surfaces with high WCA and soil repellency could be obtained with silica and mixture of hydrophobization agents which are cost effective and environmentally friendly when compared with the fluorosilane treatment.

  20. A convenient sol-gel approach to the preparation of nano-porous silica coatings with very low refractive indices.

    PubMed

    Zhang, Yulu; Zhao, Chaoxia; Wang, Pingmei; Ye, Longqiang; Luo, Jianhui; Jiang, Bo

    2014-11-18

    Silica coatings with refractive indices as low as 1.10 were prepared via a one-step base-catalysed sol-gel process using methyltriethoxysilane and tetraethoxysilane as co-precursors. No expensive equipment was required and the method did not require etching or high-temperature calcination. PMID:25253239

  1. Cellular complexity captured in durable silica biocomposites

    PubMed Central

    Kaehr, Bryan; Townson, Jason L.; Kalinich, Robin M.; Awad, Yasmine H.; Swartzentruber, B. S.; Dunphy, Darren R.; Brinker, C. Jeffrey

    2012-01-01

    Tissue-derived cultured cells exhibit a remarkable range of morphological features in vitro, depending on phenotypic expression and environmental interactions. Translation of these cellular architectures into inorganic materials would provide routes to generate hierarchical nanomaterials with stabilized structures and functions. Here, we describe the fabrication of cell/silica composites (CSCs) and their conversion to silica replicas using mammalian cells as scaffolds to direct complex structure formation. Under mildly acidic solution conditions, silica deposition is restricted to the molecularly crowded cellular template. Inter- and intracellular heterogeneity from the nano- to macroscale is captured and dimensionally preserved in CSCs following drying and subjection to extreme temperatures allowing, for instance, size and shape preserving pyrolysis of cellular architectures to form conductive carbon replicas. The structural and behavioral malleability of the starting material (cultured cells) provides opportunities to develop robust and economical biocomposites with programmed structures and functions. PMID:23045634

  2. Detection of high-silica lava flows and lava morphology at the Alarcon Rise, Gulf of California, Mexico using automated classification of the morphological-compositional relationship in AUV multibeam bathymetry and sonar backscatter

    NASA Astrophysics Data System (ADS)

    Maschmeyer, C.; White, S. M.; Dreyer, B. M.; Clague, D. A.

    2015-12-01

    An automated compositional classification by adaptive neuro-fuzzy inference system (ANFIS) was developed to study volcanic processes that create high-silica lava at oceanic ridges. The objective of this research is to determine the existence of a relationship between lava morphology and composition. Researchers from the Monterey Bay Aquarium Research Institute (MBARI) recorded morphologic observations and collected samples for geochemical analysis during ROV dives at the Alarcon Rise in 2012 and 2015. The Alarcon Rise is a unique spreading ridge environment where composition ranges from basaltic to rhyolitic, making it an ideal location to examine the compositional-morphologic relationship of lava flows. Preliminary interpretation of field data indicates that high-silica lavas are typically associated with 3-5 m, blocky pillows at the heavily faulted north end of the Alarcon. Visual analysis of multibeam bathymetry and side-scan sonar backscatter from MBARI AUV D. Allen B. and gridded at 1 m suggests that lava flow morphology (pillow, lobate, sheet) can be distinguished by seafloor roughness. Bathymetric products used by ANFIS to quantify the morphologic-compositional relationship were slope, aspect, and bathymetric position index (BPI, a measure of local height relative to the adjacent terrain). Sonar backscatter intensity is influenced by surface roughness and previously used to distinguish lava morphology. Gray-level co-occurrence matrices (GLCM) were applied to backscatter to create edge-detection filters that recognized faults and fissures. Input data are slope, aspect, bathymetric value, BPI at 100 m scale, BPI at 500 m scale, backscatter intensity, and the first principle component of backscatter GLCM. After lava morphology was classified on the Alarcon Rise map, another classification was completed to detect locations of high-silica lava. Application of an expert classifier like ANFIS to distinguish lava composition may become an important tool in oceanic

  3. In vitro osteoblast-like cell proliferation on nano-hydroxyapatite coatings with different morphologies on a titanium-niobium shape memory alloy.

    PubMed

    Xiong, Jianyu; Li, Yuncang; Hodgson, Peter D; Wen, Cui'e

    2010-12-01

    The morphology of nanomaterials significantly affects their physical, chemical, and biological properties. In the present study, nano-hydroxyapatite coatings with different morphologies were produced on the surface of a titanium-niobium shape memory alloy via a hydrothermal process. The effect of the nano-hydroxyapatite coatings on the in vitro proliferation of SaOS-2 osteoblast-like cells was investigated. Factors including crystallinity, surface micro-roughness, and surface energy of the nano-hydroxyapatite coatings were discussed. Results show that in vitro proliferation of the osteoblast-like cells was significantly enhanced on the nano-hydroxyapatite-coated titanium-niobium alloy compared to the titanium-niobium alloy without coating. The cell numbers on the nano-hydroxyapatite-coated titanium-niobium alloy changed consistently with the surface energy of the hydroxyapatite coatings. This study suggests that surface energy as a characteristic parameter influencing the in vitro proliferation of osteoblast-like cells was predominant over the crystallinity and surface micro-roughness of the nano-hydroxyapatite coatings. PMID:20725978

  4. Structural, morphological and optical properties of PEDOT:PSS/QDs nano-composite films prepared by spin-casting

    NASA Astrophysics Data System (ADS)

    Najeeb, Mansoor Ani; Abdullah, Shahino Mah; Aziz, Fakhra; Ahmad, Zubair; Rafique, Saqib; Wageh, S.; Al-Ghamdi, Ahmed A.; Sulaiman, Khaulah; Touati, Farid; Shakoor, R. A.; Al-Thani, N. J.

    2016-09-01

    This paper describes the structural, morphological and optical properties of the nano-composite of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and quantum dots (QDs). The ZnSe and CdSe QDs have been synthesized, with the aid of Mercaptoacetic acid (MAA), by a colloidal method with an average size of ~5 to 7 nm. QDs have been embedded in PEDOT:PSS using a simple solution processing approach and has been deposited as thin films by spin coating technique. The QDs embedded PEDOT:PSS enhances the light absorption spectra of samples, prominently in terms of absorption intensity which may consequently improve sensitivity of the optoelectronic devices.

  5. Comparative investigation of CuFe2O4 nano and microstructures for structural, morphological, optical and magnetic properties

    NASA Astrophysics Data System (ADS)

    Raja, G.; Gopinath, S.; Raj, R. Azhagu; Shukla, Arun K.; Alhoshan, Mansour S.; Sivakumar, K.

    2016-09-01

    CuFe2O4 nanocrystals were synthesized by the sol-gel method (SGM) and microwave method (MM) by using sucrose as a fuel. The structural, morphological, optical and magnetic properties of the products were determined and characterized in detail by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), photoluminescence (PL) spectroscopy and vibrating sample magnetometer (VSM). The XRD results confirmed the formation of cubic phase CuFe2O4. The formation of CuFe2O4 nano and microstructures were confirmed by HR-SEM. Photoluminescence emissions were determined by PL spectra, respectively. The relatively high saturation magnetization (78.22 emu/g) of CuFe2O4-MM shows that it is ferromagnetic and low saturation magnetization (35.98 emu/g) of CuFe2O4O-SGM confirms the super paramagnetic behavior.

  6. Comparison of the morphology of alkali–silica gel formed in limestones in concrete affected by the so-called alkali–carbonate reaction (ACR) and alkali–silica reaction (ASR)

    SciTech Connect

    Grattan-Bellew, P.E.; Chan, Gordon

    2013-05-15

    The morphology of alkali–silica gel formed in dolomitic limestone affected by the so-called alkali–carbonate reaction (ACR) is compared to that formed in a siliceous limestone affected by alkali–silica reaction (ASR). The particle of dolomitic limestone was extracted from the experimental sidewalk in Kingston, Ontario, Canada that was badly cracked due to ACR. The siliceous limestone particle was extracted from a core taken from a highway structure in Quebec, affected by ASR. Both cores exhibited marked reaction rims around limestone particles. The aggregate particles were polished and given a light gold coating in preparation for examination in a scanning electron microscope. The gel in the ACR aggregate formed stringers between the calcite crystals in the matrix of the rock, whereas gel in ASR concrete formed a thick layer on top of the calcite crystals, that are of the same size as in the ACR aggregate.

  7. Fabrication of silica nanostructures with a microwave assisted direct patterning process.

    PubMed

    Shin, Ju-Hyeon; Go, Bit-Na; Choi, Je-Hong; Kim, Jin-Seoung; Jung, Gun-Young; Kim, Heetae; Lee, Heon

    2014-06-01

    Silica nanostructures were fabricated on glass substrate using a microwave assisted direct patterning (MADP) process, which is a variety of soft lithography. During the MADP process using polydimethylsiloxane (PDMS), mold and microwave heating are performed simultaneously. Blanket thin film and micro- to nano-sized structures, including moth-eye patterns of SiO2, which consisted of coalesced silica nanoparticles, were formed on glass substrates from SiO2 nano-particle dispersed solutions with varied microwave heating time. Optical properties and surface morphologies of micro-sized hemisphere, nano-sized pillar, moth-eye and 50 nm sized line/space silica patterns were measured using UV-vis and a scanning electron microscope. X-ray diffraction analysis of SiO2 thin films with and without microwave heating was also carried out. PMID:24833169

  8. Fabrication of silica nanostructures with a microwave assisted direct patterning process

    NASA Astrophysics Data System (ADS)

    Shin, Ju-Hyeon; Go, Bit-Na; Choi, Je-Hong; Kim, Jin-Seoung; Jung, Gun-Young; Kim, Heetae; Lee, Heon

    2014-06-01

    Silica nanostructures were fabricated on glass substrate using a microwave assisted direct patterning (MADP) process, which is a variety of soft lithography. During the MADP process using polydimethylsiloxane (PDMS), mold and microwave heating are performed simultaneously. Blanket thin film and micro- to nano-sized structures, including moth-eye patterns of SiO2, which consisted of coalesced silica nanoparticles, were formed on glass substrates from SiO2 nano-particle dispersed solutions with varied microwave heating time. Optical properties and surface morphologies of micro-sized hemisphere, nano-sized pillar, moth-eye and 50 nm sized line/space silica patterns were measured using UV-vis and a scanning electron microscope. X-ray diffraction analysis of SiO2 thin films with and without microwave heating was also carried out.

  9. Nano-Crystal Formation and Growth from High-Fluence Ion Implantation of Au, Ag or Cu in Silica

    NASA Astrophysics Data System (ADS)

    Ila, D.; Baglin, J. E. E.; Zimmerman, R. L.

    The linear and non-linear optical properties of silica may be tailored by the introduction of a random distribution of nanocrystallites of an immiscible metal within a near-surface region. The size, size distribution, and spatial distribution of these crystallites must be controllable in order to optimize the functional properties for device applications. In this paper, we present a novel fabrication technique that offers such control. Energetic metal ions are implanted in silica at room temperature. Subsequent heat treatment leads to diffusion of the implanted atoms, nucleation and growth of metal crystallites, and Ostwald ripening of the resulting clusters. We have observed the kinetics and effective activation energies describing the multiple processes involved, for the cases of Au, Ag or Cu implanted at MeV energies, at various fluences, and then annealed at fixed temperatures in the range 500 °C-1000 °C. Effective activation energies found for nanocrystal nucleation and growth at temperatures below 800 °C (e.g. 64 meV for Ag) are replaced above this temperature range by much higher activation energies (e.g. 400 meV for Ag). We may attribute this to the depletion of un-attached mobile metal atoms (so that ripening of clusters will be limited by energy barriers for escape of such mobile atoms from small crystallites), and/or the annealing of implant-caused stress in the silica structure at high temperatures, that creates new channels for thermal diffusion of metal atoms within the silica host.

  10. Adsorbate-driven morphological changes on Cu(111) nano-pits

    DOE PAGESBeta

    Mudiyanselage, K.; Xu, F.; Hoffmann, F. M.; Hrbek, J.; Waluyo, I.; Boscoboinik, J. A.; Stacchiola, D. J.

    2014-12-09

    Adsorbate-driven morphological changes of pitted-Cu(111) surfaces have been investigated following the adsorption and desorption of CO and H. The morphology of the pitted-Cu(111) surfaces, prepared by Ar+ sputtering, exposed a few atomic layers deep nested hexagonal pits of diameters from 8 to 38 nm with steep step bundles. The roughness of pitted-Cu(111) surfaces can be healed by heating to 450-500 K in vacuum. Adsorption of CO on the pitted-Cu(111) surface leads to two infrared peaks at 2089-2090 and 2101-2105 cm-1 for CO adsorbed on under-coordinated sites in addition to the peak at 2071 cm-1 for CO adsorbed on atop sitesmore » of the close-packed Cu(111) surface. CO adsorbed on under-coordinated sites is thermally more stable than that of atop Cu(111) sites. Annealing of the CO-covered surface from 100 to 300 K leads to minor changes of the surface morphology. In contrast, annealing of a H covered surface to 300 K creates a smooth Cu(111) surface as deduced from infrared data of adsorbed CO and scanning tunnelling microscopy (STM) imaging. The observation of significant adsorbate-driven morphological changes with H is attributed to its stronger modification of the Cu(111) surface by the formation of a sub-surface hydride with a hexagonal structure, which relaxes into the healed Cu(111) surface upon hydrogen desorption. These morphological changes occur ~150 K below the temperature required for healing of the pitted-Cu(111) surface by annealing in vacuum. In contrast, the adsorption of CO, which only interacts with the top-most Cu layer and desorbs by 160 K, does not significantly change the morphology of the pitted-Cu(111) surface.« less

  11. Adsorbate-driven morphological changes on Cu(111) nano-pits

    SciTech Connect

    Mudiyanselage, K.; Xu, F.; Hoffmann, F. M.; Hrbek, J.; Waluyo, I.; Boscoboinik, J. A.; Stacchiola, D. J.

    2014-12-09

    Adsorbate-driven morphological changes of pitted-Cu(111) surfaces have been investigated following the adsorption and desorption of CO and H. The morphology of the pitted-Cu(111) surfaces, prepared by Ar+ sputtering, exposed a few atomic layers deep nested hexagonal pits of diameters from 8 to 38 nm with steep step bundles. The roughness of pitted-Cu(111) surfaces can be healed by heating to 450-500 K in vacuum. Adsorption of CO on the pitted-Cu(111) surface leads to two infrared peaks at 2089-2090 and 2101-2105 cm-1 for CO adsorbed on under-coordinated sites in addition to the peak at 2071 cm-1 for CO adsorbed on atop sites of the close-packed Cu(111) surface. CO adsorbed on under-coordinated sites is thermally more stable than that of atop Cu(111) sites. Annealing of the CO-covered surface from 100 to 300 K leads to minor changes of the surface morphology. In contrast, annealing of a H covered surface to 300 K creates a smooth Cu(111) surface as deduced from infrared data of adsorbed CO and scanning tunnelling microscopy (STM) imaging. The observation of significant adsorbate-driven morphological changes with H is attributed to its stronger modification of the Cu(111) surface by the formation of a sub-surface hydride with a hexagonal structure, which relaxes into the healed Cu(111) surface upon hydrogen desorption. These morphological changes occur ~150 K below the temperature required for healing of the pitted-Cu(111) surface by annealing in vacuum. In contrast, the adsorption of CO, which only interacts with the top-most Cu layer and desorbs by 160 K, does not significantly change the morphology of the pitted-Cu(111) surface.

  12. Structural, morphological, magnetic and dielectric characterization of nano-phased antimony doped manganese zinc ferrites

    NASA Astrophysics Data System (ADS)

    Sridhar, Ch. S. L. N.; Lakshmi, Ch. S.; Govindraj, G.; Bangarraju, S.; Satyanarayana, L.; Potukuchi, D. M.

    2016-05-01

    Nano-phased doped Mn-Zn ferrites, viz., Mn0.5-x/2Zn0.5-x/2SbXFe2O4 for x=0 to 0.3 (in steps of 0.05) prepared by hydrothermal method are characterized by X-ray diffraction, Infrared and scanning electron microscopy. XRD and SEM infer the growth of nano-crystalline cubic and hematite (α-Fe2O3) phase structures. IR reveals the ferrite phase abundance and metal ion replacement with dopant. Decreasing trend of lattice constant with dopant reflects the preferential replacement of Fe3+ions by Sb5+ion. Doping is found to cause for the decrease (i.e., 46-14 nm) of grain size. An overall trend of decreasing saturation magnetization is observed with doping. Low magnetization is attributed to the diamagnetic nature of dopant, abundance of hematite (α-Fe2O3) phase, non-stoichiometry and low temperature (800 °C) sintering conditions. Increasing Yafet-Kittel angle reflects surface spin canting to pronounce lower Ms. Lower coercivity is observed for x≤0.1, while a large Hc results for higher concentrations. High ac resistivity (~106 ohm-cm) and low dielectric loss factor (tan δ~10-2-10-3) are witnessed. Resistivity is explained on the base of a transformation in the Metal Cation-to-Oxide anion bond configuration and blockade of conductivity path. Retarded hopping (between adjacent B-sites) of carriers across the grain boundaries is addressed. Relatively higher resistivity and low dielectric loss in Sbdoped Mn-Zn ferrite systems pronounce their utility in high frequency applications.

  13. Synthesis of polymer nano-brushes by self-seeding method and study of various morphologies by AFM

    NASA Astrophysics Data System (ADS)

    Agbolaghi, S.; Abbaspoor, S.; Abbasi, F.

    2016-11-01

    Polymer brushes due to their high sensitivity to environmental changes are the best and newest means for developing the responsive materials. Polymer nano-brushes consisting various surface morphologies and uniformly distributed amorphous grafted chains were synthesized via single-crystal growth procedure. Poly(ethylene glycol)- b-polystyrene (PEG- b-PS) and poly(ethylene glycol)- b-poly(methyl methacrylate) (PEG- b-PMMA) block copolymers were prepared by atom transfer radical polymerization (ATRP). On the basis of various height differences, phase regions were detectable through atomic force microscopy (AFM NanoscopeIII). The novelty of this work is developing and characterizing the random and intermediate single-co-crystals. Besides, some other sorts of brush-covered single crystals like homo-brush and matrix-dispersed mixed-brushes were involved just for comparing the distinct morphologies. The intermediate (neither matrix-dispersed nor random) single-co-crystals were detectable through their thickness fluctuations in AFM height profiles. On the contrary, the random single-co-crystals were verified through comparing with their corresponding homopolymer and homo-brush single crystals. The growth fronts of (120), (240), (200) and (040) were detected by electron diffraction of transmission electron microscope.

  14. Development and characterization of silica and titania based nano structured materials for the removal of indoor and outdoor air pollutants

    NASA Astrophysics Data System (ADS)

    Peiris, Thelge Manindu Nirasha

    Solar energy driven catalytic systems have gained popularity in environmental remediation recently. Various photocatalytic systems have been reported in this regard and most of the photocatalysts are based on well-known semiconducting material, Titanium Dioxide, while some are based on other materials such as Silicon Dioxide and various Zeolites. However, in titania based photocatalysts, titania is actively involved in the catalytic mechanism by absorbing light and generating exitons. Because of this vast popularity of titania in the field of photocatalysis it is believed that photocatalysis mainly occurs via non-localized mechanisms and semiconductors are extremely important. Even though it is still rare, photocatalysis could be localized and possible without use of a semiconductor as well. Thus, to support localized photocatalytic systems, and to compare the activity to titania based systems, degradation of organic air pollutants by nanostructured silica, titania and mixed silica titania systems were studied. New materials were prepared using two different approaches, precipitation technique (xerogel) and aerogel preparation technique. The prepared xerogel samples were doped with both metal (silver) and non-metals (carbon and sulfur) and aerogel samples were loaded with Chromium, Cobalt and Vanadium separately, in order to achieve visible light photocatalytic activity. Characterization studies of the materials were carried out using Nova BET analysis, DR UV-vis spectrometry, powder X-ray diffraction, X-ray photoelectron Spectroscopy, FT-IR spectroscopy, Transmission Electron Microscopy, etc. Kinetics of the catalytic activities was studied using a Shimadzu GCMS-QP 5000 instrument using a closed glass reactor. All the experiments were carried out in gaseous phase using acetaldehyde as the model pollutant. Kinetic results suggest that chromium doped silica systems are good UV and visible light active photocatalysts. This is a good example for a localized

  15. Aggregate morphology of nano-TiO2: role of primary particle size, solution chemistry, and organic matter.

    PubMed

    Chowdhury, Indranil; Walker, Sharon L; Mylon, Steven E

    2013-01-01

    A systematic investigation was conducted to understand the role of aquatic conditions on the aggregate morphology of nano-TiO2, and the subsequent impact on their fate in the environment. In this study, three distinctly sized TiO2 nanoparticles (6, 13, and 23 nm) that had been synthesized with flame spray pyrolysis were employed. Nanoparticle aggregate morphology was measured using static light scattering (SLS) over a wide range of solution chemistry, and in the presence of natural organic matter (NOM). Results showed that primary nanoparticle size can significantly affect the fractal dimension of stable aggregates. A linear relationship was observed between surface areas of primary nanoparticles and fractal dimension indicating that smaller primary nanoparticles can form more compact aggregate in the aquatic environment. The pH, ionic strength, and ion valence also influenced the aggregate morphology of TNPs. Increased pH resulted a decrease in fractal dimension, whereas higher ionic strength resulted increased fractal dimension particularly for monovalent ions. When NOM was present, aggregate fractal dimension was also affected, which was also notably dependent on solution chemistry. Fractal dimension of aggregate increase for 6 nm system in the presence of NOM, whereas a drop in fractal dimension was observed for 13 nm and 23 nm aggregates. This effect was most profound for aggregates comprised of the smallest primary particles suggesting that interactions of NOM with smaller primary nanoparticles are more significant than those with larger ones. The findings from this study will be helpful for the prediction of nanoparticle aggregate fate in the aquatic environment. PMID:24592445

  16. Ultra-high density aligned Carbon-nanotube with controled nano-morphology for supercapacitors

    NASA Astrophysics Data System (ADS)

    Ghaffari, Mehdi; Zhao, Ran; Liu, Yang; Zhou, Yue; Cheng, Jiping; Guzman de Villoria, Roberto; Wardle, B. L.; Zhang, Q. M.

    2012-02-01

    Recent advances in fabricating controlled-morphology vertically aligned carbon nanotubes (VA-CNTs) with ultrahigh volume fractioncreate unique opportunities for developing unconventional supercapacitors with ultra-high energy density, power density, and long charge/discharge cycle life.Continuous paths through inter-VA-CNT channels allow fast ion transport, and high electrical conduction of the aligned CNTs in the composite electrodes lead to fast discharge speed. We investigate the charge-discharge characteristics of VA-CNTs with >20 vol% of CNT and ionic liquids as electrolytes. By employing both the electric and electromechanical spectroscopes, as well as nanostructured materials characterization, the ion transport and storage behaviors in porous electrodes are studied. The results suggest pathways for optimizing the electrode morphology in supercapacitorsusing ultra-high volume fraction VA-CNTs to further enhance performance.

  17. Maxillary sinus floor augmentation using a nano-crystalline hydroxyapatite silica gel: case series and 3-month preliminary histological results.

    PubMed

    Canullo, Luigi; Dellavia, Claudia; Heinemann, Friedhelm

    2012-03-20

    The aim of this case series is to histologically examine a new hydroxyapatite in sinus lift procedure after 3 months. Ten 2-stage sinus lifts were performed in 10 healthy patients having initial bone height of 1-2mm and bone width of 5mm, asking for a fixed implant-supported rehabilitation. After graft material augmentation, a rough-surfaced mini-implant was inserted to maintain stability of the sinus widow. A bioptical core containing a mini-implant was retrieved 3 months after maxillary sinus augmentation with NanoBone(®) and processed for undecalcified histology. From the histomorphometric analysis, NanoBone(®) residuals accounted for the 38.26% ± 8.07% of the bioptical volume, marrow spaces for the 29.23% ± 5.18% and bone for the 32.51% ± 4.96% (new bone: 20.64% ± 2.96%, native bone: 11.87% ± 3.27%). Well-mineralized regenerated bone with lamellar parallel-fibred structure and Haversian systems surrounded the residual NanoBone(®) particles. The measured bone-to-implant contact amounted to 26.02% ± 5.46%. No connective tissue was observed at the implant boundary surface. In conclusion, the tested material showed good histological outcomes also 3 months after surgery. In such critical conditions, the use of a rough-surfaced mini-implant showed BIC values supposed to be effective also in case of functional loading. Although longer follow-up and a wider patient size are needed, these preliminary results encourage further research on this biomaterial for implant load also under early stage and critical conditions. PMID:21640571

  18. Profoundly improving flow properties of a cohesive cellulose powder by surface coating with nano-silica through comilling.

    PubMed

    Chattoraj, Sayantan; Shi, Limin; Sun, Changquan Calvin

    2011-11-01

    Poor flow properties hinder the easy handling of powders during industrial-scale processing. In this work, we show that powder flow can be substantially improved by reducing the cohesion of powders by coating them with nanosized guest particles. We further show that comilling is an efficient process for nanocoating. We have systematically investigated the effects of total number of comilling cycles (10-70 cycles) and silica loading (0-1.0 wt %) on the flow behavior of a highly cohesive and poorly flowing grade of microcrystalline cellulose powder (Avicel PH105). Optimum flow enhancement has been achieved with 1.0 wt % silica loading at 40 comilling cycles. The flow properties of nanocoated Avicel PH105 are comparable to those of Avicel PH102, which exhibits adequate flowability for processing on a high-speed tablet press. Comilling is fast and suitable for continuous processing. It shows potential for addressing industrial powder handling problems caused by poor powder flow properties. PMID:21698602

  19. The Effect of Novel Synthetic Methods and Parameters Control on Morphology of Nano-alumina Particles.

    PubMed

    Xie, Yadian; Kocaefe, Duygu; Kocaefe, Yasar; Cheng, Johnathan; Liu, Wei

    2016-12-01

    Alumina is an inorganic material, which is widely used in ceramics, catalysts, catalyst supports, ion exchange and other fields. The micromorphology of alumina determines its application in high tech and value-added industry and its development prospects. This paper gives an overview of the liquid phase synthetic method of alumina preparation, combined with the mechanism of its action. The present work focuses on the effects of various factors such as concentration, temperature, pH, additives, reaction system and methods of calcination on the morphology of alumina during its preparation. PMID:27206644

  20. The Effect of Novel Synthetic Methods and Parameters Control on Morphology of Nano-alumina Particles

    NASA Astrophysics Data System (ADS)

    Xie, Yadian; Kocaefe, Duygu; Kocaefe, Yasar; Cheng, Johnathan; Liu, Wei

    2016-05-01

    Alumina is an inorganic material, which is widely used in ceramics, catalysts, catalyst supports, ion exchange and other fields. The micromorphology of alumina determines its application in high tech and value-added industry and its development prospects. This paper gives an overview of the liquid phase synthetic method of alumina preparation, combined with the mechanism of its action. The present work focuses on the effects of various factors such as concentration, temperature, pH, additives, reaction system and methods of calcination on the morphology of alumina during its preparation.

  1. From nano to micro: topographical scale and its impact on cell adhesion, morphology and contact guidance

    NASA Astrophysics Data System (ADS)

    Nguyen, Anh Tuan; Sathe, Sharvari R.; Yim, Evelyn K. F.

    2016-05-01

    Topography, among other physical factors such as substrate stiffness and extracellular forces, is known to have a great influence on cell behaviours. Optimization of topographical features, in particular topographical dimensions ranging from nanoscale to microscale, is the key strategy to obtain the best cellular performance for various applications in tissue engineering and regenerative medicine. In this review, we provide a comprehensive survey on the significance of sizes of topography and their impacts on cell adhesion, morphology and alignment, and neurite guidance. Also recent works mimicking the hierarchical structure of natural extracellular matrix by combining both nanoscale and microscale topographies are highlighted.

  2. From nano to micro: topographical scale and its impact on cell adhesion, morphology and contact guidance.

    PubMed

    Nguyen, Anh Tuan; Sathe, Sharvari R; Yim, Evelyn K F

    2016-05-11

    Topography, among other physical factors such as substrate stiffness and extracellular forces, is known to have a great influence on cell behaviours. Optimization of topographical features, in particular topographical dimensions ranging from nanoscale to microscale, is the key strategy to obtain the best cellular performance for various applications in tissue engineering and regenerative medicine. In this review, we provide a comprehensive survey on the significance of sizes of topography and their impacts on cell adhesion, morphology and alignment, and neurite guidance. Also recent works mimicking the hierarchical structure of natural extracellular matrix by combining both nanoscale and microscale topographies are highlighted. PMID:27066850

  3. Peptide-Decorated Gold Nanoparticles as Functional Nano-Capping Agent of Mesoporous Silica Container for Targeting Drug Delivery.

    PubMed

    Chen, Ganchao; Xie, Yusheng; Peltier, Raoul; Lei, Haipeng; Wang, Ping; Chen, Jun; Hu, Yi; Wang, Feng; Yao, Xi; Sun, Hongyan

    2016-05-11

    A stimuli-responsive drug delivery system (DDS) with bioactive surface is constructed by end-capping mesoporous silica nanoparticles (MSNs) with functional peptide-coated gold nanoparticles (GNPs). MSNs are first functionalized with acid-labile α-amide-β-carboxyl groups to carry negative charges, and then capped with positively charged GNPs that are decorated with oligo-lysine-containing peptide. The resulting hybrid delivery system exhibits endo/lysosomal pH triggered drug release, and the incorporation of RGD peptide facilitates targeting delivery to αvβ3 integrin overexpressing cancer cells. The system can serve as a platform for preparing diversified multifunctional nanocomposites using various functional inorganic nanoparticles and bioactive peptides. PMID:27102225

  4. Morphological properties of Al-doped ZnO nano/microstructures

    NASA Astrophysics Data System (ADS)

    Kim, Kyung Ho; Umakoshi, Tomoyuki; Abe, Yoshio; Kawamura, Midori; Kiba, Takayuki

    2016-03-01

    We discussed the morphological properties of Al-doped zinc oxide (Al-ZnO) microrods grown on a ZnO seed layer and precipitation particles and compared them with undoped ZnO samples. The ZnO nanorods grown on a ZnO seed layer were dense and perpendicular to the surface of the substrate, i.e., fluorine-doped tin oxide (FTO). In contrast the Al-ZnO grew as larger microrods, and the rods were sparsely and obliquely arranged. Precipitation particles synthesized in the ZnO solution through homogeneous nucleation had flower-like structures assembled from the rods and individual rods with lengths of several micrometers. Al-ZnO precipitation particles consisted of rods with length of several micrometers and hexagonal nanoplates. Fourier transform infrared (FTIR) analysis results showed that the rods and precipitation particles had the good chemical properties of ZnO. Both size and morphology of the rods could be effectively controlled by adding aluminum nitrate (Al(NO3)3) as dopant in the ZnO rod solution.

  5. Morphology of Nano and Micro Fiber Structures in Ultrafine Particles Filtration

    SciTech Connect

    Kimmer, Dusan; Vincent, Ivo; Fenyk, Jan; Petras, David; Zatloukal, Martin; Sambaer, Wannes; Zdimal, Vladimir

    2011-07-15

    Selected procedures permitting to prepare homogeneous nanofibre structures of the desired morphology by employing a suitable combination of variables during the electrospinning process are presented. A comparison (at the same pressure drop) was made of filtration capabilities of planar polyurethane nanostructures formed exclusively by nanofibres, space polycarbonate nanostructures having bead spacers, structures formed by a combination of polymethyl methacrylate micro- and nanofibres and polypropylene meltblown microstructures, through which ultrafine particles of ammonium sulphate 20-400 nm in size were filtered. The structures studied were described using a new digital image analysis technique based on black and white images obtained by scanning electron microscopy. More voluminous structures modified with distance microspheres and having a greater thickness and mass per square area of the material, i.e. structures possessing better mechanical properties, demanded so much in nanostructures, enable preparation of filters having approximately the same free volume fraction as flat nanofibre filters but an increased effective fibre surface area, changed pore size morphology and, consequently, a higher filter quality.

  6. Simultaneous Determination of Se and Te in Ores by HG-AFS After Online Preconcentration with Nano-TiO2 Immobilized on Silica Gel.

    PubMed

    Zhou, Jing-rong; Deng, Dong-yan; Huang, Ke; Tian, Yun-fei; Hou, Xian-deng

    2015-09-01

    A simple, sensitive and interference-free method was established for simultaneous determination of trace selenium and tellurium in ore samples by HG-AFS, by using nano-TiO2 immobilized on a silica gel packed microcolumn for online preconcentration. Selenium and tellurium were selectively adsorbed to the microcolumn in acidic condition and then completely eluted with 2% (m/v) NaOH solution. The experimental conditions for hydride generation, adsorption, elution and potential interference were investigated in detail. Under the optimum conditions, the detection limits of selenium and tellurium by the proposed method with 180 s sampling time were 4.0 and 3.6 ng · L(-1), with sensitivity enhancement of 20- and 13-fold compared to conventional hydride generation method, respectively. The relative standard deviation (RSD, n=5) of this method for 1 μg · L(-1) Se(IV) and Te(IV) were 0.7% and 2.3%, respectively. This method was applied to determination of selenium and tellurium in several ore samples. PMID:26669138

  7. Bimodal porous silica microspheres decorated with polydopamine nano-particles for the adsorption of methylene blue in fixed-bed columns.

    PubMed

    Ataei-Germi, Taher; Nematollahzadeh, Ali

    2016-05-15

    Bimodal meso/macro-porous silica microspheres (MSM) were synthesized by a modified sol-emulsion-gel method and then the surface was coated with polydopamine (PDA) nano-particles of 39nm in size. Focusing on the encouraging properties of the synthesized adsorbent, such as high specific surface area (612.3m(2)g(-1), because of mesopores), fast mass transfer (0.9-2.67×10(-3)mLmin(-1)mg, because of macropores), and abundant "adhesive" functional groups of PDA, it was used for the removal of methylene blue (MB) from aqueous solution in a fixed-bed column. The effect of different parameters such as pH, initial concentration, and flow rate was studied. The results revealed that an appropriate sorption condition is an alkaline solution of MB (e.g., pH 10) at low flow rate (less than 5mLmin(-1)). Furthermore, the compatibility of the experimental data with mathematical models such as Thomas and Adams-Bohart was investigated. Both of the models showed a good agreement with the experimental data (R(2)=0.9954-0.9994), and could be applied for the prediction of the column properties and breakthrough curves. Regeneration of the column was performed by using HCl solution with a concentration of 0.1M as an eluent. PMID:26943002

  8. Effects of silica nanoparticles on copper nanowire dispersions in aqueous PVA solutions

    NASA Astrophysics Data System (ADS)

    Lee, Seung Hak; Song, Hyeong Yong; Hyun, Kyu

    2016-05-01

    In this study, the effects of adding silica nanoparticles to PVA/CuNW suspensions were investigated rheologically, in particular, by small and large amplitude oscillatory shear (SAOS and LAOS) test. Interesting, the SAOS test showed the complex viscosities of CuNW/silica based PVA matrix were smaller than those of PVA/CuNW without silica. These phenomena show that nano-sized silica affects the dispersion of CuNW in aqueous PVA, which suggests small particles can prevent CuNW aggregation. Nonlinearity (third relative intensity ≡ I 3/1) was calculated from LAOS test results using Fourier Transform rheology (FT-rheology) and nonlinear linear viscoelastic ratio (NLR) value was calculated using the nonlinear parameter Q and complex modulus G*. Nonlinearity ( I 3/1) results showed more CuNW aggregation in PVA/CuNW without silica than in PVA/CuNW with silica. NLR (= [ Q 0( ϕ)/ Q 0(0)]/[ G*( ϕ)/ G*(0)]) results revealed an optimum concentration ratio of silica to CuNW to achieve a well-dispersed state. Degree of dispersion was assessed through the simple optical method. SAOS and LAOS test, and dried film morphologies showed nano-sized silica can improve CuNW dispersion in aqueous PVA solutions.

  9. The filler-rubber interface in styrene butadiene nanocomposites with anisotropic silica particles: morphology and dynamic properties.

    PubMed

    Tadiello, L; D'Arienzo, M; Di Credico, B; Hanel, T; Matejka, L; Mauri, M; Morazzoni, F; Simonutti, R; Spirkova, M; Scotti, R

    2015-05-28

    Silica-styrene butadiene rubber (SBR) nanocomposites were prepared by using shape-controlled spherical and rod-like silica nanoparticles (NPs) with different aspect ratios (AR = 1-5), obtained by a sol-gel route assisted by a structure directing agent. The nanocomposites were used as models to study the influence of the particle shape on the formation of nanoscale immobilized rubber at the silica-rubber interface and its effect on the dynamic-mechanical behavior. TEM and AFM tapping mode analyses of nanocomposites demonstrated that the silica particles are surrounded by a rubber layer immobilized at the particle surface. The spherical filler showed small contact zones between neighboring particles in contact with thin rubber layers, while anisotropic particles (AR > 2) formed domains of rods preferentially aligned along the main axis. A detailed analysis of the polymer chain mobility by different time domain nuclear magnetic resonance (TD-NMR) techniques evidenced a population of rigid rubber chains surrounding particles, whose amount increases with the particle anisotropy, even in the absence of significant differences in terms of chemical crosslinking. Dynamic measurements demonstrate that rod-like particles induce stronger reinforcement of rubber, increasing with the AR. This was related to the self-alignment of the anisotropic silica particles in domains able to immobilize rubber. PMID:25899456

  10. Morphology-controlled synthesis of Ag{sub 3}PO{sub 4} nano/microcrystals and their antibacterial properties

    SciTech Connect

    Wu, Aiping; Tian, Chungui; Chang, Wei; Hong, Yu; Zhang, Qi; Qu, Yang; Fu, Honggang

    2013-09-01

    Graphical abstract: The Ag{sub 3}PO{sub 4} with rhombic dodecahedral, spherical and small size particles were controllable fabricated just by changing the types of the solvent. The materials possess good antibacterial properties toward different kinds of bacteria. - Highlights: • The Ag{sub 3}PO{sub 4} with three morphologies were controllable fabricated. • The Ag{sub 3}PO{sub 4} as-prepared possess obvious antibacterial properties in the dark. • The antibacterial ability of Ag{sub 3}PO{sub 4} could be greatly improved under the visible light irradiation. - Abstract: We reported the controllable fabrication of Ag{sub 3}PO{sub 4} nano/microcrystals through a simple solution-based precipitation reaction. The samples were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy and infrared spectroscopy. The results indicated that the Ag{sub 3}PO{sub 4} crystals with three different morphology, including the rhombic dodecahedron of 500 nm, the sphere of 100 nm and the particles with small-size of 20 nm, could be obtained in the solvents of water, ethylene glycol (EG) and dimethyl sulfoxide (DMSO). The antibacterial assay showed that all samples possess obvious antibacterial properties. In addition, the Ag{sub 3}PO{sub 4} with small size of 20 nm showed better activity due to their high specific surface areas. Notably, we have found that the antibacterial ability of Ag{sub 3}PO{sub 4} could be greatly improved under the visible light irradiation, which are superior to that in the dark and commercial streptomycin.

  11. Morphological Characterisation of Unstained and Intact Tissue Micro-architecture by X-ray Computed Micro- and Nano-Tomography

    NASA Astrophysics Data System (ADS)

    Walton, Lucy A.; Bradley, Robert S.; Withers, Philip J.; Newton, Victoria L.; Watson, Rachel E. B.; Austin, Clare; Sherratt, Michael J.

    2015-05-01

    Characterisation and quantification of tissue structures is limited by sectioning-induced artefacts and by the difficulties of visualising and segmenting 3D volumes. Here we demonstrate that, even in the absence of X-ray contrast agents, X-ray computed microtomography (microCT) and nanotomography (nanoCT) can circumvent these problems by rapidly resolving compositionally discrete 3D tissue regions (such as the collagen-rich adventitia and elastin-rich lamellae in intact rat arteries) which in turn can be segmented due to their different X-ray opacities and morphologies. We then establish, using X-ray tomograms of both unpressurised and pressurised arteries that intra-luminal pressure not only increases lumen cross-sectional area and straightens medial elastic lamellae but also induces profound remodelling of the adventitial layer. Finally we apply microCT to another human organ (skin) to visualise the cell-rich epidermis and extracellular matrix-rich dermis and to show that conventional histological and immunohistochemical staining protocols are compatible with prior X-ray exposure. As a consequence we suggest that microCT could be combined with optical microscopy to characterise the 3D structure and composition of archival paraffin embedded biological materials and of mechanically stressed dynamic tissues such as the heart, lungs and tendons.

  12. Morphological Characterisation of Unstained and Intact Tissue Micro-architecture by X-ray Computed Micro- and Nano-Tomography.

    PubMed

    Walton, Lucy A; Bradley, Robert S; Withers, Philip J; Newton, Victoria L; Watson, Rachel E B; Austin, Clare; Sherratt, Michael J

    2015-01-01

    Characterisation and quantification of tissue structures is limited by sectioning-induced artefacts and by the difficulties of visualising and segmenting 3D volumes. Here we demonstrate that, even in the absence of X-ray contrast agents, X-ray computed microtomography (microCT) and nanotomography (nanoCT) can circumvent these problems by rapidly resolving compositionally discrete 3D tissue regions (such as the collagen-rich adventitia and elastin-rich lamellae in intact rat arteries) which in turn can be segmented due to their different X-ray opacities and morphologies. We then establish, using X-ray tomograms of both unpressurised and pressurised arteries that intra-luminal pressure not only increases lumen cross-sectional area and straightens medial elastic lamellae but also induces profound remodelling of the adventitial layer. Finally we apply microCT to another human organ (skin) to visualise the cell-rich epidermis and extracellular matrix-rich dermis and to show that conventional histological and immunohistochemical staining protocols are compatible with prior X-ray exposure. As a consequence we suggest that microCT could be combined with optical microscopy to characterise the 3D structure and composition of archival paraffin embedded biological materials and of mechanically stressed dynamic tissues such as the heart, lungs and tendons. PMID:25975937

  13. Sintering effects on structure, morphology, and electrical properties of sol-gel synthesized, nano-crystalline erbium oxide

    NASA Astrophysics Data System (ADS)

    Bakhsh, Allah; Maqsood, Asghari

    2012-12-01

    The nano-crystalline erbium oxide powder was synthesized through the sol-gel technique. The effect of sintering temperature from 250°C to 1400°C on structure, morphology, and electrical properties was studied. The results were compared with the microcrystalline erbium oxide purchased from the market. The synthesized erbium oxide showed fiber like nanostructures. Dielectric properties at different sintering temperatures were measured in the frequency range 100 Hz to 5MHz. The synthesized erbium oxide had the highest dielectric constant at 650°C. The behavior of the dissipation factor tan δ for sol-gel synthesized material was distinct from that of the purchased material; it was higher at low frequencies and then decreased with the increase in frequency. The synthesized material sintered at different temperatures exhibited a similar sort of frequency-dependent response for permittivity (ɛ) and resistivity ( ρ). This was in accordance with Koop's theory of dielectrics. For the microcrystalline material, frequency dependence of permittivity and resistivity was not uniform. The results showed that sol-gel synthesized erbium oxide could be a good candidate for high-k applications.

  14. Morphological Characterisation of Unstained and Intact Tissue Micro-architecture by X-ray Computed Micro- and Nano-Tomography

    PubMed Central

    Walton, Lucy A.; Bradley, Robert S.; Withers, Philip J.; Newton, Victoria L.; Watson, Rachel E. B.; Austin, Clare; Sherratt, Michael J.

    2015-01-01

    Characterisation and quantification of tissue structures is limited by sectioning-induced artefacts and by the difficulties of visualising and segmenting 3D volumes. Here we demonstrate that, even in the absence of X-ray contrast agents, X-ray computed microtomography (microCT) and nanotomography (nanoCT) can circumvent these problems by rapidly resolving compositionally discrete 3D tissue regions (such as the collagen-rich adventitia and elastin-rich lamellae in intact rat arteries) which in turn can be segmented due to their different X-ray opacities and morphologies. We then establish, using X-ray tomograms of both unpressurised and pressurised arteries that intra-luminal pressure not only increases lumen cross-sectional area and straightens medial elastic lamellae but also induces profound remodelling of the adventitial layer. Finally we apply microCT to another human organ (skin) to visualise the cell-rich epidermis and extracellular matrix-rich dermis and to show that conventional histological and immunohistochemical staining protocols are compatible with prior X-ray exposure. As a consequence we suggest that microCT could be combined with optical microscopy to characterise the 3D structure and composition of archival paraffin embedded biological materials and of mechanically stressed dynamic tissues such as the heart, lungs and tendons. PMID:25975937

  15. Plasma enhanced chemical vapour deposition of silica onto Ti: Analysis of surface chemistry, morphology and functional hydroxyl groups

    PubMed Central

    Szili, Endre J.; Kumar, Sunil; Smart, Roger St. C.; Lowe, Rachel; Saiz, Eduardo; Voelcker, Nicolas H.

    2009-01-01

    Previously, we have developed and characterised a procedure for the deposition of thin silica films by a plasma enhanced chemical vapour deposition (PECVD) procedure using tetraethoxysilane (TEOS) as the main precursor. We have used the silica coatings for improving the corrosion resistance of metals and for enhancing the bioactivity of biomedical metallic implants. Recently, we have been fine-tuning the PECVD method for producing high quality and reproducible PECVD-silica (PECVD-Si) coatings on metals, primarily for biomaterial applications. In order to understand the interaction of the PECVD-Si coatings with biological species (such as proteins and cells), it is important to first analyse the properties of the silica films deposited using the optimised parameters. Therefore, this current investigation was carried out to analyse the characteristic features of PECVD-Si deposited on Ti substrates (PECVD-Si-Ti). We determined that the PECVD-Si coatings on Ti were conformal to the substrate surface, strongly adhered to the underlying substrate and were resistant to delamination. The PECVD-Si surface was composed of stoichiometric SiO2, showed a low carbon content (below 10 at.%) and was very hydrophilic (contact angle <10°). Finally, we also showed that the PECVD-Si coatings contain functional hydroxyl groups. PMID:19809536

  16. Morphology and porosity characteristics control of SBA-16 mesoporous silica. Effect of the triblock surfactant Pluronic F127 degradation during the synthesis

    NASA Astrophysics Data System (ADS)

    Mesa, Monica; Sierra, Ligia; Patarin, Joël; Guth, Jean-Louis

    2005-08-01

    The use of a reaction mixture, characterized by high dilution (H 2O/TEOS = 495), low to medium acid concentration (0.4-1.6 M HCl) and the presence of a cosurfactant (CTMABr), allows the synthesis of micron-sized particles of SBA-16 type mesoporous silica with different morphologies and structural characteristics. With a F127/TEOS molar ratio around 0.005 and a temperature between 70 °C and 95 °C, perfect rhombododecahedra (∅ 2-8 μm) are obtained. High acid concentration (1.6 M HCl) and/or temperature higher than 100 °C produce a smoothening of the edges and lead to the formation of spherical particles. This morphology is also favoured by low F127/TEOS molar ratios and corresponds to a disordered mesoporous structure. At a temperature of 40 °C or lower, the gel-like particles with poorly organized mesostructure are difficult to transform into well-organized materials. High F127/TEOS molar ratios lead to the same result. These different behaviours can be rationalized taking into account the strength of the interactions between the surfactant and the silica species which depends on the conformation of the hydrophilic poly-ethylene-oxide chains. Temperature and acid concentration are the main parameters to modify the conformation. But these two parameters are also responsible of the degradation of the Pluronic F127.

  17. A multifunctional role of trialkylbenzenes for the preparation of aqueous colloidal mesostructured/mesoporous silica nanoparticles with controlled pore size, particle diameter, and morphology

    NASA Astrophysics Data System (ADS)

    Yamada, Hironori; Ujiie, Hiroto; Urata, Chihiro; Yamamoto, Eisuke; Yamauchi, Yusuke; Kuroda, Kazuyuki

    2015-11-01

    Both the pore size and particle diameter of aqueous colloidal mesostructured/mesoporous silica nanoparticles (CMSS/CMPS) derived from tetrapropoxysilane were effectively and easily controlled by the addition of trialkylbenzenes (TAB). Aqueous highly dispersed CMPS with large pores were successfully obtained through removal of surfactants and TAB by a dialysis process. The pore size (from 4 nm to 8 nm) and particle diameter (from 50 nm to 380 nm) were more effectively enlarged by the addition of 1,3,5-triisopropylbenzene (TIPB) than 1,3,5-trimethylbenzene (TMB), and the enlargement did not cause the variation of the mesostructure and particle morphology. The larger molecular size and higher hydrophobicity of TIPB than TMB induce the incorporation of TIPB into micelles without the structural change. When TMB was used as TAB, the pore size of CMSS was also enlarged while the mesostructure and particle morphology were varied. Interestingly, when tetramethoxysilane and TIPB were used, CMSS with a very small particle diameter (20 nm) with concave surfaces and large mesopores were obtained, which may strongly be related to the initial nucleation of CMSS. A judicious choice of TAB and Si sources is quite important to control the mesostructure, size of mesopores, particle diameter, and morphology.Both the pore size and particle diameter of aqueous colloidal mesostructured/mesoporous silica nanoparticles (CMSS/CMPS) derived from tetrapropoxysilane were effectively and easily controlled by the addition of trialkylbenzenes (TAB). Aqueous highly dispersed CMPS with large pores were successfully obtained through removal of surfactants and TAB by a dialysis process. The pore size (from 4 nm to 8 nm) and particle diameter (from 50 nm to 380 nm) were more effectively enlarged by the addition of 1,3,5-triisopropylbenzene (TIPB) than 1,3,5-trimethylbenzene (TMB), and the enlargement did not cause the variation of the mesostructure and particle morphology. The larger molecular size

  18. Optical, structural and morphological studies of (ZnO) nano-rod thin films for biosensor applications using sol gel technique

    NASA Astrophysics Data System (ADS)

    Wahab, H. A.; Salama, A. A.; El-Saeid, A. A.; Nur, O.; Willander, M.; Battisha, I. K.

    Uniformly distributed ZnO nano-rods (NRs) with diameters in nano-scale have been successfully grown in two stages; the first at annealing temperature (250-300 °C) for seed layer preparation on glass substrate by using sol gel technique and the second at low temperature (90-95 °C) by aqueous chemical growth (ACG) method. The same prepared thin film samples were grown on the surface of silver wire (0.25 mm in diameters) to produce electrochemical nano-sensors. The structure and the morphology of the prepared samples will be evaluated using XRD, Scanning electron microscope SEM. The absorption coefficient (α) and the band gap (Eg) for ZnO NRs thin films were determined. (α) was decreased by increasing the annealing temperature due to the increase of the surface roughness caused by higher temperature, where the creation of surface roughness gives rise to multi-reflections which, capture the reflected radiation and enhance the absorptivity. We are presenting an iron ion (Fe3+) potentiometric sensor based on functionalized ZnO nano-rods with selective iono-phore (18 crown 6). Zinc oxide nanorods (NRs) thin films with a diameter of about 68 up to 94 nm were grown on silver wire and gold coated glass.

  19. 3D Non-destructive morphological analysis of a solid oxide fuel cell anode using full-field X-ray nano-tomography

    NASA Astrophysics Data System (ADS)

    Karen Chen-Wiegart, Yu-chen; Cronin, J. Scott; Yuan, Qingxi; Yakal-Kremski, Kyle J.; Barnett, Scott A.; Wang, Jun

    2012-11-01

    An accurate 3D morphological analysis is critically needed to study the process-structure-property relationship in many application fields such as battery electrodes, fuel cells and porous materials for sensing and actuating. Here we present the application of a newly developed full field X-ray nano-scale transmission microscopy (TXM) imaging for a non-destructive, comprehensive 3D morphology analysis of a porous Ni-YSZ solid oxide fuel cell anode. A unique combination of improved 3D resolution and large analyzed volume (˜3600 μm3) yields structural data with excellent statistical accuracy. 3D morphological parameters quantified include phase volume fractions, surface and interfacial area densities, phase size distribution, directional connectivity, tortuosity, and electrochemically active triple phase boundary density. A prediction of electrochemical anode polarization resistance based on this microstructural data yielded good agreement with a measured anode resistance via electrochemical impedance spectroscopy. The Mclachlan model is used to estimate the anode electrical conductivity.

  20. Nanoscale plasticity in silica glass

    SciTech Connect

    Glosli, J.N.; Boercker, D.B.; Tesar, A.; Belak, J.

    1993-10-01

    Mechanisms of nano-scale plasticity and damage initiation in silica glass is examined using molecular dynamics simulation. Computer experiments are carried out by indenting a sharp diamond-like tool, containing 4496 atoms, into a silica slab consisting of 12288 atoms. Both elastic and plastic deformation of silica is observed during nanoindentation simulation; this transition occurs at an indentation of 1.25 nm, and the calculated hardness (15GPa for 1.5 nm indentation) agrees with experiment.

  1. Synthesis of manganese incorporated hierarchical mesoporous silica nanosphere with fibrous morphology by facile one-pot approach for efficient catalytic ozonation.

    PubMed

    Afzal, Shahzad; Quan, Xie; Chen, Shuo; Wang, Jing; Muhammad, Dost

    2016-11-15

    Manganese incorporated fibrous silica nanosphere (MnOx-0.013/KCC-1) was synthesized by one step hydrothermal method for the first time and its catalytic activity for ozonation of oxalic acid was studied. For comparison, manganese loaded MCM-41 (MnOx-0.013/MCM-41) was prepared by impregnation method. Various characterizations showed that the morphological, structural and textural properties of MnOx-0.013/KCC-1 were well preserved. Ozonation and catalytic ozonation by MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41 led to 4, 85 and 60% reduction in TOC respectively. Furthermore, 0.05 and 1.2mgL(-1) leaching of Mn was detected from MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41, which are approximately 2.0 and 42.0% of the total Mn present in MnOx-0.013/KCC-1 and MnOx-0.013/MCM-41 respectively. The high catalytic activity was attributed to the generation of hydroxyl radical. Surface hydroxyl groups investigated by using phosphates and ATR-FTIR were believed to be the active sites. Our proposed method of synthesis can be generalized for the synthesis of other metal oxides incorporated fibrous silica for environmental catalysis and other catalytic reactions. PMID:27434734

  2. Growth, Morphology, and Electrical Characterization of Polyaniline-ZnO Nano-composite Langmuir-Blodgett Thin Films

    NASA Astrophysics Data System (ADS)

    Bhullar, Gurpreet Kaur; Kaur, Ramneek; Raina, K. K.

    2015-10-01

    Polyaniline (PANi)-zinc oxide (ZnO) nano-composites were prepared by chemical polymerization of aniline doped with ZnO nanoparticles. Surface pressure-area ( π-A) isotherms for the PANi-ZnO nano-composite revealed phase transformations of the monolayer during compression. Langmuir-Blodgett (LB) films of PANi and PANi-ZnO nano-composite were characterized by use of UV-visible (UV-Vis) and Fourier-transform infrared spectroscopy, atomic force microscopy, and conductive atomic force microscopy (C-AFM). Local current-voltage ( I- V) characteristics revealed the current range for PANi-ZnO nano-composite LB films was larger than that for PANi LB films. Conductive data images were recorded to investigate charge-transport current inhomogeneities in the LB films.

  3. Photoinduced charge generation rates in soluble P3HT : PCBM nano-aggregates predict the solvent-dependent film morphology.

    PubMed

    Roy, Palas; Jha, Ajay; Dasgupta, Jyotishman

    2016-02-01

    The device efficiency of bulk heterojunction (BHJ) solar cells is critically dependent on the nano-morphology of the solution-processed polymer : fullerene blend. Active control on blend morphology can only emanate from a detailed understanding of solution structures during the film casting process. Here we use photoinduced charge transfer (CT) rates to probe the effective length scale of the pre-formed solution structures and their energy disorder arising from a mixture of poly(3-hexylthiophene-2,5-diyl) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) in three different organic solvents. The observed solvent-dependent ultrafast biphasic rise of the transient polaron state in solution along with changes detected in the C=C stretching frequency of bound PCBM provides direct evidence for film-like P3HT : PCBM interfaces in solution. Using the diffusive component of the charge transfer rate, we deduce ∼3-times larger functional nano-domain size in toluene than in chlorobenzene thereby correctly predicting the relative polymer nanofiber widths observed in annealed films. We thus provide first experimental evidence for the postulated polymer : fullerene : solvent ternary phase that seeds the eventual morphology in spin-cast films. Our work motivates the design of new chemical additives to tune the grain size of the evolving polymer : fullerene domains within the solution phase. PMID:26763690

  4. Surface modification of nano-silica on the ligament advanced reinforcement system for accelerated bone formation: primary human osteoblasts testing in vitro and animal testing in vivo

    NASA Astrophysics Data System (ADS)

    Li, Mengmeng; Wang, Shiwen; Jiang, Jia; Sun, Jiashu; Li, Yuzhuo; Huang, Deyong; Long, Yun-Ze; Zheng, Wenfu; Chen, Shiyi; Jiang, Xingyu

    2015-04-01

    The Ligament Advanced Reinforcement System (LARS) has been considered as a promising graft for ligament reconstruction. To improve its biocompatibility and effectiveness on new bone formation, we modified the surface of a polyethylene terephthalate (PET) ligament with nanoscale silica using atom transfer radical polymerization (ATRP) and silica polymerization. The modified ligament is tested by both in vitro and in vivo experiments. Human osteoblast testing in vitro exhibits an ~21% higher value in cell viability for silica-modified grafts compared with original grafts. Animal testing in vivo shows that there is new formed bone in the case of a nanoscale silica-coated ligament. These results demonstrate that our approach for nanoscale silica surface modification on LARS could be potentially applied for ligament reconstruction.The Ligament Advanced Reinforcement System (LARS) has been considered as a promising graft for ligament reconstruction. To improve its biocompatibility and effectiveness on new bone formation, we modified the surface of a polyethylene terephthalate (PET) ligament with nanoscale silica using atom transfer radical polymerization (ATRP) and silica polymerization. The modified ligament is tested by both in vitro and in vivo experiments. Human osteoblast testing in vitro exhibits an ~21% higher value in cell viability for silica-modified grafts compared with original grafts. Animal testing in vivo shows that there is new formed bone in the case of a nanoscale silica-coated ligament. These results demonstrate that our approach for nanoscale silica surface modification on LARS could be potentially applied for ligament reconstruction. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr01439e

  5. Core-shell-structured silica/polyacrylate particles prepared by Pickering emulsion: influence of the nucleation model on particle interfacial organization and emulsion stability

    PubMed Central

    2014-01-01

    This work reports a new evidence of the versatility of silica sol as a stabilizer for Pickering emulsions. The organization of silica particles at the oil-water interface is a function of the nucleation model. The present results show that nucleation model, together with monomer hydrophobicity, can be used as a trigger to modify the packing density of silica particles at the oil-water interface: Less hydrophobic methylmethacrylate, more wettable with silica particles, favors the formation of core-shell-structured composite when the composite particles are prepared by miniemulsion polymerization in which monomers are fed in batch (droplet nucleation). By contrast, hydrophobic butylacrylate promotes the encapsulating efficiency of silica when monomers are fed dropwise (homogeneous nucleation). The morphologies of polyacrylate-nano-SiO2 composites prepared from different feed ratio of methylmethacrylate/butylacrylate (with different hydrophobicity) and by different feed processes are characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. The results from SEM and TEM show that the morphologies of the as-prepared polyacrylate/nano-SiO2 composite can be a core-shell structure or a bare acrylic sphere. The stability of resulting emulsions composed of these composite particles is strongly dependent on the surface coverage of silica particles. The emulsion stability is improved by densely silica-packed composite particles. PMID:25313299

  6. The structure, morphology, and the metal-enhanced fluorescence of nano-Ag/ZnO core-shell structure

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Ding, Yanli; Peng, Xiang; Zhou, Mingtao; Liang, Xiaoyan; Min, Jiahua; Wang, Linjun; Shi, Weimin

    2015-06-01

    Nano-polyc rystalline silver (Ag) particles with the diameter of 60 nm were synthesized by the reducing agent sodium citrate. An amorphous zinc oxide (ZnO) shell layer was then coated on the surface of silver particles using wet chemical method. The Ag/ZnO core-shell structure was characterized by scanning electron microscope, transmission electron microscopy, ultraviolet-visible spectroscopy and fluorescence (FL) measurement. The results showed that nano-Ag/ZnO core-shell particles with an average diameter of ~100 nm were prepared successfully, and the FL intensity of Rhodamine 6G (R6G) mixed with Ag/ZnO nanoparticle was 53 % greater than that of the same amount of R6G without any nanoparticles, which may be related to the effect of surface plasmon resonance.

  7. The structure, morphology, and the metal-enhanced fluorescence of nano-Ag/ZnO core-shell structure

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Ding, Yanli; Peng, Xiang; Zhou, Mingtao; Liang, Xiaoyan; Min, Jiahua; Wang, Linjun; Shi, Weimin

    2014-09-01

    Nano-polyc rystalline silver (Ag) particles with the diameter of 60 nm were synthesized by the reducing agent sodium citrate. An amorphous zinc oxide (ZnO) shell layer was then coated on the surface of silver particles using wet chemical method. The Ag/ZnO core-shell structure was characterized by scanning electron microscope, transmission electron microscopy, ultraviolet-visible spectroscopy and fluorescence (FL) measurement. The results showed that nano-Ag/ZnO core-shell particles with an average diameter of ~100 nm were prepared successfully, and the FL intensity of Rhodamine 6G (R6G) mixed with Ag/ZnO nanoparticle was 53 % greater than that of the same amount of R6G without any nanoparticles, which may be related to the effect of surface plasmon resonance.

  8. SIZE AND DENSITY ESTIMATION FROM IMPACT TRACK MORPHOLOGY IN SILICA AEROGEL: APPLICATION TO DUST FROM COMET 81P/WILD 2

    SciTech Connect

    Niimi, Rei; Tsuchiyama, Akira; Kadono, Toshihiko; Okudaira, Kyoko; Hasegawa, Sunao; Tabata, Makoto; Watanabe, Takayuki; Yagishita, Masahito; Machii, Nagisa; Nakamura, Akiko M.; Uesugi, Kentaro; Takeuchi, Akihisa; Nakano, Tsukasa

    2012-01-01

    A large number of cometary dust particles were captured with low-density silica aerogel during the NASA Stardust mission. The dust particles penetrated into the aerogel and formed various track shapes. To estimate the properties of the dust particles, such as density and size, based on the morphology of the tracks, we carried out systematic experiments testing impacts into low-density aerogel at 6 km s{sup -1} using projectiles of various sizes and densities. We found that the maximum track diameter and the ratio of the track length to the maximum track diameter in aerogel are good indicators of projectile size and density, respectively. Based on these results, we estimated the size and density of individual dust particles from comet 81P/Wild 2. The average density of the 'fluffy' dust particles and the bulk density of all dust particles were obtained as 0.35 {+-} 0.07 and 0.49 {+-} 0.18 g cm{sup -3}, respectively. These statistical data provided the content of monolithic and coarse grains in the Stardust particles, {approx}30 wt%. Combining this result with some mid-infrared observational data, we found that the content of crystalline silicates is {approx}50 wt% or more of non-volatile material.

  9. Morphology Controllable Synthesis of ScF3:Er3+, Yb3+ Nano/Sub-Microncrystals by Hydrothermal/Solvothermal Process.

    PubMed

    Han, Lili; Li, Hua; Ci, Zhipeng; Wang, Yuhua

    2016-04-01

    In this paper, red phosphors Yb3+-Er3+ co-doped ScF3 nano/microcrystals were successfully prepared by a facile hydrothermal/solvothermal route using the sodium dodecyl benzene sulfonate (SDBS) as the surfactant. The structure, morphologies and up-conversion (UC) photoluminescence properties of the as-prepared products were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectra, respectively. The SEM images show that the obtained samples are the uniform cubic and cuboid crystals. With the increase of the surfactant SDBS or the change in the solvent types, the sample change their size from nanometer to submicron. Upon the 980 nm laser diode excitation, the ScF3:Era+, Yb3+ nanocrystals exhibit red emission which can be assigned to the characteristic 4F9/2/4I15/2 transition of Er3+. In order to understand the emission mechanisms of ScF3:ErS+, Yb3+ nanocrystals, the dependence of UC luminescence intensity on the 980 nm excitation power was measured, suggesting that the UC phenomenon results from a two-photon process. Meanwhile, the emission intensities of the YbS+-Er3+ codoped ScF3 nano/sub-micro crystals with different solution composition show an obvious change under the 980 nm laser excitation. Therefore, the phosphors Yb3+-Er3+ co-doped ScF3 possibly have a potential application in the biological applications. PMID:27451694

  10. Gas-phase supersaturation effects on morphology properties of ZnO nano and microstructures grown by PVT

    NASA Astrophysics Data System (ADS)

    Montenegro, D. N.; Martínez Tomas, M. C.; Muñoz Sanjosé, V.; Sallet, V.

    2016-02-01

    A systematic study of the morphology evolution of ZnO nanostructures grown by physical vapour transport was carried out. The evolution of the shape with the growth time is shown to depend on the different gas-phase supersaturation and temperature conditions encountered in the crystallization zone of the tube furnace. The observed morphology transitions are discussed, and a growth model for ZnO nanostructures is given.

  11. STEM characterization on silica nanowires with new mesopore structures by space-confined self-assembly within nano-scale channels

    SciTech Connect

    Lai, Peng; Hu, Michael Z.; Shi, Donglu; Blom, Douglas Allen

    2008-01-01

    Critical channel diameters were found (below which space confinement takes effect, leading to more uniform and ordered mesopore structures) in the study of evaporation-induced coassembly of triblock-copolymer (P123) and silica molecular precursors (TEOS, tetraethyl orthosilicate) by employing channels in anodized aluminum oxide (AAO, 13 200 nm channel diameter) and in track-etched polycarbonate (EPC, 10 80 nm channel diameter) and for the first time we have observed a new mesopore structure (i.e., packed hollow spheres) in silica nanowires formed in AAO channels with diameters from 30 to 80 nm.

  12. Microwave-assisted combustion synthesis of nano iron oxide/iron-coated activated carbon, anthracite, cellulose fiber, and silica, with arsenic adsorption studies

    EPA Science Inventory

    Combustion synthesis of iron oxide/iron coated carbons such as activated carbon, anthracite, cellulose fiber and silica is described. The reactions were carried out in alumina crucibles using a Panasonic kitchen microwave with inverter technology, and the reaction process was com...

  13. Characterization of polymer-silica nanocomposite particles with core-shell morphologies using Monte Carlo simulations and small angle X-ray scattering.

    PubMed

    Balmer, Jennifer A; Mykhaylyk, Oleksandr O; Schmid, Andreas; Armes, Steven P; Fairclough, J Patrick A; Ryan, Anthony J

    2011-07-01

    A two-population model based on standard small-angle X-ray scattering (SAXS) equations is verified for the analysis of core-shell structures comprising spherical colloidal particles with particulate shells. First, Monte Carlo simulations of core-shell structures are performed to demonstrate the applicability of the model. Three possible shell packings are considered: ordered silica shells due to either charge-dependent repulsive or size-dependent Lennard-Jones interactions or randomly arranged silica particles. In most cases, the two-population model produces an excellent fit to calculated SAXS patterns for the simulated core-shell structures, together with a good correlation between the fitting parameters and structural parameters used for the simulation. The limits of application are discussed, and then, this two-population model is applied to the analysis of well-defined core-shell vinyl polymer/silica nanocomposite particles, where the shell comprises a monolayer of spherical silica nanoparticles. Comprehensive SAXS analysis of a series of poly(styrene-co-n-butyl acrylate)/silica colloidal nanocomposite particles (prepared by the in situ emulsion copolymerization of styrene and n-butyl acrylate in the presence of a glycerol-functionalized silica sol) allows the overall core-shell particle diameter, the copolymer latex core diameter and polydispersity, the mean silica shell thickness, the mean silica diameter and polydispersity, the volume fractions of the two components, the silica packing density, and the silica shell structure to be obtained. These experimental SAXS results are consistent with electron microscopy, dynamic light scattering, thermogravimetry, helium pycnometry, and BET surface area studies. The high electron density contrast between the (co)polymer and the silica components, together with the relatively low polydispersity of these core-shell nanocomposite particles, makes SAXS ideally suited for the characterization of this system. Moreover

  14. In-situ synthesis of Au nano particles of co-existing morphologies in liquid crystalline matrix

    SciTech Connect

    Dan, Kaustabh Datta, Alokmay

    2015-06-24

    The present study describes the in-situ synthesis of Au nano particles (Au-NP) in the room temperature nematic liquid crystalline (LC) substance MBBA (N-4 methoxybenzylidene 4 butylaniline) without any external reducing or stabilizing agents. UV-Visible absorption and fluorescence spectroscopy clearly show formation of Au-NP within the LC matrix through the plasmon resonance peak for the NPs and EDAX measurements confirm this formation. Transmission electron Microscopy shows co-existence of spherical and prismatic NPs. FTIR spectroscopy shows a considerable shift in the C=N stretch band pointing to the location of the growth centre of the NPs. Polarization microscopy data indicates a definite phase ordering and texture transformation from Nematic to highly ordered smectic mesophase.

  15. In-situ synthesis of Au nano particles of co-existing morphologies in liquid crystalline matrix

    NASA Astrophysics Data System (ADS)

    Dan, Kaustabh; Datta, Alokmay

    2015-06-01

    The present study describes the in-situ synthesis of Au nano particles (Au-NP) in the room temperature nematic liquid crystalline (LC) substance MBBA (N-4 methoxybenzylidene 4 butylaniline) without any external reducing or stabilizing agents. UV-Visible absorption and fluorescence spectroscopy clearly show formation of Au-NP within the LC matrix through the plasmon resonance peak for the NPs and EDAX measurements confirm this formation. Transmission electron Microscopy shows co-existence of spherical and prismatic NPs. FTIR spectroscopy shows a considerable shift in the C=N stretch band pointing to the location of the growth centre of the NPs. Polarization microscopy data indicates a definite phase ordering and texture transformation from Nematic to highly ordered smectic mesophase.

  16. Nanoporous TiO2 nanoparticle assemblies with mesoscale morphologies: nano-cabbage versus sea-anemone.

    PubMed

    Darbandi, Masih; Gebre, Tesfaye; Mitchell, Lucas; Erwin, William; Bardhan, Rizia; Levan, M Douglas; Mochena, Mogus D; Dickerson, James H

    2014-06-01

    We report the novel synthesis of nanoporous TiO2 nanoparticle ensembles with unique mesoscale morphologies. Constituent nanoparticles evolved into multifaceted assemblies, exhibiting excellent crystallinity and enhanced photocatalytic activity compared with commercial TiO2. Such materials could be exploited for applications, like organic pollutant degradation. PMID:24760418

  17. The effects of pulse electrodeposition parameters on morphology, hardness and wear behavior of nano-structure Cr-WC composite coatings

    NASA Astrophysics Data System (ADS)

    Rezaei-Sameti, M.; Nadali, S.; Rajabi, J.; Rakhshi, M.

    2012-08-01

    Electrodeposition of nano-structured Cr-WC had been carried out from a trivalent chromium bath using a square shaped pulse current. The average size of WC particles was 70 nm. The effect of pulse electroplating parameters such as current density and duty cycle on the amount of incorporated WC particles and morphology of the coatings was investigated. The structure and morphology of the coatings were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. In addition, the hardness and tribological behavior of the coatings were investigated by micro hardness and pin on disk methods, respectively. The results showed that with decreasing duty cycle, the volume percentage, hardness and wear resistance of coating increased. Also, by increasing the current density up to 15 A/dm2, the both of volume percentage and hardness will increase. An increase in current density up to 20 A/dm2, had an inverse results. Finally the optimum wear resistance was achieved at the current density of 8 A/dm2, duty cycle of 50%.

  18. Nanoporous TiO2 nanoparticle assemblies with mesoscale morphologies: nano-cabbage versus sea-anemone

    NASA Astrophysics Data System (ADS)

    Darbandi, Masih; Gebre, Tesfaye; Mitchell, Lucas; Erwin, William; Bardhan, Rizia; Levan, M. Douglas; Mochena, Mogus D.; Dickerson, James H.

    2014-05-01

    We report the novel synthesis of nanoporous TiO2 nanoparticle ensembles with unique mesoscale morphologies. Constituent nanoparticles evolved into multifaceted assemblies, exhibiting excellent crystallinity and enhanced photocatalytic activity compared with commercial TiO2. Such materials could be exploited for applications, like organic pollutant degradation.We report the novel synthesis of nanoporous TiO2 nanoparticle ensembles with unique mesoscale morphologies. Constituent nanoparticles evolved into multifaceted assemblies, exhibiting excellent crystallinity and enhanced photocatalytic activity compared with commercial TiO2. Such materials could be exploited for applications, like organic pollutant degradation. Electronic supplementary information (ESI) available: Synthesis and characterization procedures, TEM/XRD of samples prepared at different temperature and water content, table of nitrogen adsorption-desorption values of different samples. See DOI: 10.1039/c3nr06154j

  19. Nano-morphology induced additional surface plasmon resonance enhancement of SERS sensitivity in Ag/GaN nanowall network

    NASA Astrophysics Data System (ADS)

    Sharvani, S.; Upadhayaya, Kishor; Kumari, Gayatri; Narayana, Chandrabhas; Shivaprasad, S. M.

    2015-11-01

    The GaN nanowall network, formed by opening the screw dislocations by kinetically controlled MBE growth, possesses a large surface and high conductivity. Sharp apexed nanowalls show higher surface electron concentration in the band-tail states, in comparison to blunt apexed nanowalls. Uncapped silver nanoparticles are vapor deposited on the blunt and sharp GaN nanowall networks to study the morphological dependence of band-edge plasmon-coupling. Surface enhanced Raman spectroscopy studies performed with a rhodamine 6G analyte on these two configurations clearly show that the sharp nanowall morphology with smaller Ag nanoparticles shows higher enhancement of the Raman signal. A very large enhancement factor of 2.8 × 107 and a very low limit of detection of 10-10 M is observed, which is attributed to the surface plasmon resonance owing to the high surface electron concentration on the GaN nanowall in addition to that of the Ag nanoparticles. The significantly higher sensitivity with same-sized Ag nanoparticles confirms the unconventional role of morphology-dependent surface charge carrier concentration of GaN nanowalls in the enhancement of Raman signals.

  20. Nano-morphology induced additional surface plasmon resonance enhancement of SERS sensitivity in Ag/GaN nanowall network.

    PubMed

    Sharvani, S; Upadhayaya, Kishor; Kumari, Gayatri; Narayana, Chandrabhas; Shivaprasad, S M

    2015-11-20

    The GaN nanowall network, formed by opening the screw dislocations by kinetically controlled MBE growth, possesses a large surface and high conductivity. Sharp apexed nanowalls show higher surface electron concentration in the band-tail states, in comparison to blunt apexed nanowalls. Uncapped silver nanoparticles are vapor deposited on the blunt and sharp GaN nanowall networks to study the morphological dependence of band-edge plasmon-coupling. Surface enhanced Raman spectroscopy studies performed with a rhodamine 6G analyte on these two configurations clearly show that the sharp nanowall morphology with smaller Ag nanoparticles shows higher enhancement of the Raman signal. A very large enhancement factor of 2.8 × 10(7) and a very low limit of detection of 10(-10) M is observed, which is attributed to the surface plasmon resonance owing to the high surface electron concentration on the GaN nanowall in addition to that of the Ag nanoparticles. The significantly higher sensitivity with same-sized Ag nanoparticles confirms the unconventional role of morphology-dependent surface charge carrier concentration of GaN nanowalls in the enhancement of Raman signals. PMID:26502004

  1. Cellulose-silica aerogels.

    PubMed

    Demilecamps, Arnaud; Beauger, Christian; Hildenbrand, Claudia; Rigacci, Arnaud; Budtova, Tatiana

    2015-05-20

    Aerogels based on interpenetrated cellulose-silica networks were prepared and characterised. Wet coagulated cellulose was impregnated with silica phase, polyethoxydisiloxane, using two methods: (i) molecular diffusion and (ii) forced flow induced by pressure difference. The latter allowed an enormous decrease in the impregnation times, by almost three orders of magnitude, for a sample with the same geometry. In both cases, nanostructured silica gel was in situ formed inside cellulose matrix. Nitrogen adsorption analysis revealed an almost threefold increase in pores specific surface area, from cellulose aerogel alone to organic-inorganic composite. Morphology, thermal conductivity and mechanical properties under uniaxial compression were investigated. Thermal conductivity of composite aerogels was lower than that of cellulose aerogel due to the formation of superinsulating mesoporous silica inside cellulose pores. Furthermore, composite aerogels were stiffer than each of reference aerogels. PMID:25817671

  2. Inducing an Order–Order Morphological Transition via Chemical Degradation of Amphiphilic Diblock Copolymer Nano-Objects

    PubMed Central

    2016-01-01

    The disulfide-based cyclic monomer, 3-methylidene-1,9-dioxa-5,12,13-trithiacyclopentadecane-2,8-dione (MTC), is statistically copolymerized with 2-hydroxypropyl methacrylate to form a range of diblock copolymer nano-objects via reversible addition–fragmentation chain transfer (RAFT) polymerization. Poly(glycerol monomethacrylate) (PGMA) is employed as the hydrophilic stabilizer block in this aqueous polymerization-induced self-assembly (PISA) formulation, which affords pure spheres, worms or vesicles depending on the target degree of polymerization for the core-forming block. When relatively low levels (<1 mol %) of MTC are incorporated, high monomer conversions (>99%) are achieved and high blocking efficiencies are observed, as judged by 1H NMR spectroscopy and gel permeation chromatography (GPC), respectively. However, the side reactions that are known to occur when cyclic allylic sulfides such as MTC are statistically copolymerized with methacrylic comonomers lead to relatively broad molecular weight distributions. Nevertheless, the worm-like nanoparticles obtained via PISA can be successfully transformed into spherical nanoparticles by addition of excess tris(2-carboxyethyl)phosphine (TCEP) at pH 8–9. Surprisingly, DLS and TEM studies indicate that the time scale needed for this order–order transition is significantly longer than that required for cleavage of the disulfide bonds located in the worm cores indicated by GPC analysis. This reductive degradation pathway may enable the use of these chemically degradable nanoparticles in biomedical applications, such as drug delivery systems and responsive biomaterials. PMID:27228898

  3. Inducing an Order-Order Morphological Transition via Chemical Degradation of Amphiphilic Diblock Copolymer Nano-Objects.

    PubMed

    Ratcliffe, Liam P D; Couchon, Claudie; Armes, Steven P; Paulusse, Jos M J

    2016-06-13

    The disulfide-based cyclic monomer, 3-methylidene-1,9-dioxa-5,12,13-trithiacyclopentadecane-2,8-dione (MTC), is statistically copolymerized with 2-hydroxypropyl methacrylate to form a range of diblock copolymer nano-objects via reversible addition-fragmentation chain transfer (RAFT) polymerization. Poly(glycerol monomethacrylate) (PGMA) is employed as the hydrophilic stabilizer block in this aqueous polymerization-induced self-assembly (PISA) formulation, which affords pure spheres, worms or vesicles depending on the target degree of polymerization for the core-forming block. When relatively low levels (<1 mol %) of MTC are incorporated, high monomer conversions (>99%) are achieved and high blocking efficiencies are observed, as judged by (1)H NMR spectroscopy and gel permeation chromatography (GPC), respectively. However, the side reactions that are known to occur when cyclic allylic sulfides such as MTC are statistically copolymerized with methacrylic comonomers lead to relatively broad molecular weight distributions. Nevertheless, the worm-like nanoparticles obtained via PISA can be successfully transformed into spherical nanoparticles by addition of excess tris(2-carboxyethyl)phosphine (TCEP) at pH 8-9. Surprisingly, DLS and TEM studies indicate that the time scale needed for this order-order transition is significantly longer than that required for cleavage of the disulfide bonds located in the worm cores indicated by GPC analysis. This reductive degradation pathway may enable the use of these chemically degradable nanoparticles in biomedical applications, such as drug delivery systems and responsive biomaterials. PMID:27228898

  4. Multiscale Micro-Nano Nested Structures: Engineered Surface Morphology for Efficient Light Escaping in Organic Light-Emitting Diodes.

    PubMed

    Zhou, Lei; Dong, Xiaoxuan; Zhou, Yun; Su, Wenming; Chen, Xiaolian; Zhu, Yufu; Shen, Su

    2015-12-01

    Various micro-to-nanometer scale structures are extremely attractive for light escaping in organic light-emitting diodes. To develop and optimize such structures, an innovative approach was demonstrated for the first time to fabricate multiscale micro-nano nested structures by photolithography with a well-designed mask pattern followed by a controllable thermal reflow process. The experimental and theoretical characterizations verify that these unique nested structures hold the capability of light concentration, noticeable low haze, and efficient antireflection. As a proof-of-concept, the incorporation of this pattern onto the glass substrate efficiently facilitates light escaping from the device, resulting in current efficiency 1.60 times and external quantum efficiency 1.63 times that of a control flat device, respectively. Moreover, compared to a hexagonally arranged microlens array and quasi-random biomimetic moth eye nanostructures, the nested structures proposed here can magically tune the spatial emission profile to comply with the Lambertian radiation pattern. Hence, this novel structure is expected to be of great potential in related ubiquitous optoelectronic applications and provide scientific inspiration to other novel multiscale micro-nanostructure research. PMID:26575428

  5. Solvent induced rapid modulation of micro/nano structures of metal carboxylates coordination polymers: mechanism and morphology dependent magnetism

    PubMed Central

    Liu, Kun; Shen, Zhu-Rui; Li, Yue; Han, Song-De; Hu, Tong-Liang; Zhang, Da-Shuai; Bu, Xian-He; Ruan, Wen-Juan

    2014-01-01

    Rational modulation of morphology is very important for functional coordination polymers (CPs) micro/nanostructures, and new strategies are still desired to achieve this challenging target. Herein, organic solvents have been established as the capping agents for rapid modulating the growth of metal-carboxylates CPs in organic solvent/water mixtures at ambient conditions. Co-3,5-pyridinedicarboxylate (pydc) CPs was studied here as the example. During the reaction, the organic solvents exhibited three types of modulation effect: anisotropic growth, anisotropic growth/formation of new crystalline phase and the formation of new crystalline phase solely, which was due to the variation of their binding ability with metal cations. The following study revealed that the binding ability was critically affected by their functional groups and molecular size. Moreover, their modulation effect could be finely tuned by changing volume ratios of solvent mixtures. Furthermore, they could be applied for modulating other metal-carboxylates CPs: Co-1,3,5-benzenetricarboxylic (BTC), Zn-pydc and Eu-pydc etc. Additionally, the as-prepared Co-pydc CPs showed a fascinating morphology-dependent antiferromagnetic behavior. PMID:25113225

  6. Silica Fillers for elastomer Reinforement

    SciTech Connect

    Kohls, D.J.; Schaefer, D.W.

    2009-08-26

    This article summarizes recent work on the structure of precipitated silica used in the reinforcement of elastomers. Silica has a unique morphology, consisting of multiple structural levels that can be controlled through processing. The ability to control and characterize the multiple structures of precipitated silica is an example of morphological engineering for reinforcement applications. In this summary of some recent research efforts using precipitated silica, small-angle scattering techniques are described and their usefulness for determining the morphology of silica in terms of primary particles, aggregates, and agglomerates are discussed. The structure of several different precipitated silica powders is shown as well as the mechanical properties of elastomers reinforced with these silica particles. The study of the mechanical properties of filled elastomer systems is a challenging and exciting topic for both fundamental science and industrial application. It is known that the addition of hard particulates to a soft elastomer matrix results in properties that do not follow a straightforward rule of mixtures. Research efforts in this area have shown that the properties of filled elastomers are influenced by the nature of both the filler and the matrix, as well as the interactions between them. Several articles have reviewed the influence of fillers like silica and carbon black on the reinforcement of elastomers. In general, the structure-property relationships developed for filled elastomers have evolved into the following major areas: Filler structure, hydrodynamic reinforcement, and interactions between fillers and elastomers.

  7. Silica Fillers for elastomer Reinforement

    SciTech Connect

    Kohls, D.J.; Schaefer, D.W.

    2012-09-10

    This article summarizes recent work on the structure of precipitated silica used in the reinforcement of elastomers. Silica has a unique morphology, consisting of multiple structural levels that can be controlled through processing. The ability to control and characterize the multiple structures of precipitated silica is an example of morphological engineering for reinforcement applications. In this summary of some recent research efforts using precipitated silica, small-angle scattering techniques are described and their usefulness for determining the morphology of silica in terms of primary particles, aggregates, and agglomerates are discussed. The structure of several different precipitated silica powders is shown as well as the mechanical properties of elastomers reinforced with these silica particles. The study of the mechanical properties of filled elastomer systems is a challenging and exciting topic for both fundamental science and industrial application. It is known that the addition of hard particulates to a soft elastomer matrix results in properties that do not follow a straightforward rule of mixtures. Research efforts in this area have shown that the properties of filled elastomers are influenced by the nature of both the filler and the matrix, as well as the interactions between them. Several articles have reviewed the influence of fillers like silica and carbon black on the reinforcement of elastomers. In general, the structure-property relationships developed for filled elastomers have evolved into the following major areas: Filler structure, hydrodynamic reinforcement, and interactions between fillers and elastomers.

  8. In-situ growth of porous alumino-silicates and fabrication of nano-porous membranes

    NASA Astrophysics Data System (ADS)

    Kodumuri, Pradeep

    2009-12-01

    Feasibility of depositing continuous films of nano-porous alumino-silicates, primarily zeolites and MCM-41, on metallic and non-metallic substrates was examined with an aim to develop membranes for separation of gaseous mixtures and also for application as hydrogen storage material. Mesoporous silica was deposited in-side the pores of these nano-porous disks with an aim to develop membranes for selective separations. Our study involves supported zeolite film growth on substrates using in-situ hydrothermal synthesis. Faujasite, Silicalite and Mesoporous silica have been grown on various metallic and non-metallic supports. Metallic substrates used for film growth included anodized titanium, sodium hydroxide treated Titanium, Anodized aluminum, and sintered copper. A non-metallic substrate used was nano-porous aluminum oxide. Zeolite film growth was characterized using Scanning Electron Microscope (AMRAY 1820) and High Resolution Transmission electron microscope. Silicalite was found to grow uniformly on all the substrates to form a uniform and closely packed film. Faujasite tends to grow in the form of individual particles which do not inter-grow like silicalite to form a continuous film. Mesoporous silica was found to grow uniformly on anodized aluminum compared to growth on sintered copper and anodized titanium. Mesoporous silica growth on AnodiscRTM was found to cover more than half the surface of the substrate. Commercially obtained AnodiscRTM was found to have cylindrical channels of the pore branching into each other and since we needed pore channels of uniform dimension for Mesoporous silica growth, we have fabricated nano-porous alumina with uniform pore channels. Nano-porous alumina membranes containing uniform distribution of through thickness cylindrical pore channels were fabricated using anodization of aluminum disks. Free-standing nano-porous alumina membranes were used as templates for electro-deposition in order to fabricate nickel and palladium nano

  9. Seeded Growth of Highly Luminescent CdSe/CdS Nano-Heterostructures with Rod and Tetrapod Morphologies

    SciTech Connect

    Talapin, Dmitri; Talapin, Dmitri V.; Nelson, James H.; Shevchenko, Elena V.; Aloni, Shaul; Sadtler, Bryce; Alivisatos, A. Paul

    2007-08-09

    We have demonstrated that seeded growth of nanocrystals offers a convenient way to design nanoheterostructures with complex shapes and morphologies by changing the crystalline structure of the seed. By using Use nanocrystals with wurtzite and zinc blende structure as seeds for growth of US nanorods, we synthesized CdSe/CdS heterostructure nanorods and nanotetrapods, respectively. Both of these structures showed excellent luminescentproperties, combining high photoluminescence efficiency (similar to 80 and similar to 50percent for nanorods and nanotetrapods, correspondingly), giant extinction coefficients (similar to 2 x 10(7) and similar to 1.5 x 10(8) M-1 cm (-1) at 350 nm for nanorods and nanotetrapods, correspondingly), and efficient energy transfer from the US arms into the emitting CdSe Core.

  10. Grafting of [(64)Cu]-TPPF20 porphyrin complex on Functionalized nano-porous MCM-41 silica as a potential cancer imaging agent.

    PubMed

    Fazaeli, Yousef; Feizi, Shahzad; Jalilian, Amir R; Hejrani, Ali

    2016-06-01

    Mesoporous silica, MCM-41, functionalized with 3-aminopropyltriethoxysilane (APTES) was investigated as a potential drug delivery system, using [(64)Cu]-5, 10, 15, 20-tetrakis penta fluorophenyl porphyrin complex. [(64)Cu]-TPPF20 complex was grafted on functionalized MCM-41. The product was characterized by paper chromatography, FTIR spectroscopy, low angle X-ray diffraction, CHN and TGA/DTA analyses and atomic force microscopy. The biological evaluations of the grafted complex, [(64)Cu]-TPPF20@NH2-MCM-41, were done in Fibrosarcoma tumor-bearing Sprague-Dawley rats using scarification studies and Sopha DST-XL Dual-Head SPECT system. The actual loading amount of aminopropyl groups was found about 1.6mmol per gram of final silica. The specific activity of the final compound was found to be 3Ci/g. Amine functionalized MCM-41 was found to be a good platform for theranostic radiopharmaceuticals such as copper-64 complexes. Considering the accumulation of the tracer in tumor cells, fast wash-out from normal tissues, the short half-life copper-64 and less imposed radiation doses to patients, [(64)Cu]-TPPF20@NH2-MCM-41 can potentially be a suitable candidate for tumor imaging applications and future PET studies. PMID:26974487