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Sample records for silica film formulated

  1. Mesoporous silica formulation strategies for drug dissolution enhancement: a review.

    Science.gov (United States)

    McCarthy, Carol A; Ahern, Robert J; Dontireddy, Rakesh; Ryan, Katie B; Crean, Abina M

    2016-01-01

    Silica materials, in particular mesoporous silicas, have demonstrated excellent properties to enhance the oral bioavailability of poorly water-soluble drugs. Current research in this area is focused on investigating the kinetic profile of drug release from these carriers and manufacturing approaches to scale-up production for commercial manufacture. This review provides an overview of different methods utilized to load drugs onto mesoporous silica carriers. The influence of silica properties and silica pore architecture on drug loading and release are discussed. The kinetics of drug release from mesoporous silica systems is examined and the manufacturability and stability of these formulations are reviewed. Finally, the future prospects of mesoporous silica drug delivery systems are considered. Substantial progress has been made in the characterization and development of mesoporous drug delivery systems for drug dissolution enhancement. However, more research is required to fully understand the drug release kinetic profile from mesoporous silica materials. Incomplete drug release from the carrier and the possibility of drug re-adsorption onto the silica surface need to be investigated. Issues to be addressed include the manufacturability and regulation status of formulation approaches employing mesoporous silica to enhance drug dissolution. While more research is needed to support the move of this technology from the bench to a commercial medicinal product, it is a realistic prospect for the near future.

  2. Solvent free amorphisation for pediatric formulations (minitablets) using mesoporous silica

    DEFF Research Database (Denmark)

    Monsuur, Fred; Choudhari, Yogesh; Reddy, Upendra

    2016-01-01

    Introduction: Most silica based amorphisation strategies are using organic solvent loading methods. Towards pediatric formulations this is creating concerns. With this in mind the development of a dry amorphisation strategy was the focus of this study. The high internal surface area of mesoporous...... silica gel is densely crowded with silanol groups, which can provide hydrogen-bonding possibilities with a drug, potentially resulting in amorphisation. Purpose: Amorphous drugs provide an advantage in solubility; however, their low physical stability always remained concern. Additional there was a need...... to understand the mechanism and variables of dry amorphisation. Method: Ibuprofen (IBU) and Syloid® silica at different ratios were co-milled at variable milling times between 1 and 90 min. The interaction with; and amorphisation of IBU; on Syloid® silica was analyzed using SEM, FTIR, DSC and XRD. The co...

  3. Characterization of transparent silica films deposited on polymeric materials

    International Nuclear Information System (INIS)

    Teshima, K.; Sugimura, H.; Inoue, Y.; Takai, O.

    2002-01-01

    Silica films were synthesized by capacitively coupled RF PECVD using mixtures of organo-silane and oxygen as a source. The chemical bonding states and compositions of the films deposited were evaluated with FTIR and XPS. Film surfaces and cross-sections were observed by SEM. Oxygen transmission rates (OTR) of the films coated on polyethylene terephthalate (PET) substrates were measured by an isopiestic method. (Authors)

  4. Alternative secondary accelerator for silica-filled natural rubber formulations

    NARCIS (Netherlands)

    Kaewsakul, Wisut; Sahakaro, Kannika; Dierkes, Wilma K.; Noordermeer, Jacobus W.M.

    2013-01-01

    Dithiophosphate (DTP) displays a good efficiency towards improved overall properties of silica-reinforced natural rubber compounds, when it is used as secondary accelerator in a sulfenamide primary accelerated sulfur vulcanization system. Comparing DTP with diphenylguanidine (DPG), DTP is more

  5. Influence of Nano Silica on Alkyd Films

    DEFF Research Database (Denmark)

    Nikolic, Miroslav

    . The present work centers on the reinforcement of alkyd binders emulsified in water and used in exterior wood coatings with nano silica. Raman spectroscopy was used throughout the study to maintain the reproducibility of results as it was found that colloidal nano silica can increase or decrease the speed...... of alkyd curing affecting the tested mechanical properties. Hydrophilic, colloidal nano silica was seen to have limited effect in improving the mechanical properties due to problems in properly dispersing and attaining good surface interactions with the hydrophobic alkyd polymer. Efforts in increasing...... the interactions with the alkyd polymer while keeping the nano filler stable in the water phase did not show further improvements of mechanical properties. The best results in respect to mechanical properties, as measured under static and dynamic loading, were obtained with the use of hexamethyldisilazane treated...

  6. Densification of zirconia films by coevaporation with silica

    International Nuclear Information System (INIS)

    Feldman, A.; Farabaugh, E.N.

    1985-04-01

    Optical films of zirconia have been receiving considerable attention because of their potential use as the high-index layer in multilayer optical coatings for the ultraviolet portion of the spectrum. Several problems are associated with electron-beam deposited zirconia films, including index instability and index inhomogeneity. The index instability is caused by the adsorption and the desorption of water in the porous columnar structure of the zirconia films. Index inhomogeneity is due to the inhomogeneous structure in the films. Recent work has shown that the first several tens of nanometers of a film possess a cubic structure, whereas the outmost layers possess a monoclinic structure. One approach for producing bulk-like zirzonia films that is receiving considerable attention at present is ion-assisted electron-beam deposition. This is because the method has successfully produced zirconia films having bulk-like densities and refractive indices that show insignificant sensitivity to water adsorption. In this paper a similar effect is demonstrated when mixed zirconia:silica films are produced by coevaporation from independent electron-beam sources, and, in particular, it is shown that the admixture of a small amount of silica with the zirconia produces a film possessing a higher refractive index than a pure zirconia film

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

    Directory of Open Access Journals (Sweden)

    S. Abdalla

    Full Text Available 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. Keywords: Dielectric break down, Polymers, Nano-composite, Colloidal silica

  8. Colloidal silica films for high-capacity DNA arrays

    Science.gov (United States)

    Glazer, Marc Irving

    The human genome project has greatly expanded the amount of genetic information available to researchers, but before this vast new source of data can be fully utilized, techniques for rapid, large-scale analysis of DNA and RNA must continue to develop. DNA arrays have emerged as a powerful new technology for analyzing genomic samples in a highly parallel format. The detection sensitivity of these arrays is dependent on the quantity and density of immobilized probe molecules. We have investigated substrates with a porous, "three-dimensional" surface layer as a means of increasing the surface area available for the synthesis of oligonucleotide probes, thereby increasing the number of available probes and the amount of detectable bound target. Porous colloidal silica films were created by two techniques. In the first approach, films were deposited by spin-coating silica colloid suspensions onto flat glass substrates, with the pores being formed by the natural voids between the solid particles (typically 23nm pores, 35% porosity). In the second approach, latex particles were co-deposited with the silica and then pyrolyzed, creating films with larger pores (36 nm), higher porosity (65%), and higher surface area. For 0.3 mum films, enhancements of eight to ten-fold and 12- to 14-fold were achieved with the pure silica films and the films "templated" with polymer latex, respectively. In gene expression assays for up to 7,000 genes using complex biological samples, the high-capacity films provided enhanced signals and performed equivalently or better than planar glass on all other functional measures, confirming that colloidal silica films are a promising platform for high-capacity DNA arrays. We have also investigated the kinetics of hybridization on planar glass and high-capacity substrates. Adsorption on planar arrays is similar to ideal Langmuir-type adsorption, although with an "overshoot" at high solution concentration. Hybridization on high-capacity films is

  9. Atomic Structure Control of Silica Thin Films on Pt(111)

    KAUST Repository

    Crampton, Andrew S

    2015-05-27

    Metal oxide thin films grown on metal single crystals are commonly used to model heterogeneous catalyst supports. The structure and properties of thin silicon dioxide films grown on metal single crystals have only recently been thoroughly characterized and their spectral properties well established. We report the successful growth of a three- dimensional, vitreous silicon dioxide thin film on the Pt(111) surface and reproduce the closed bilayer structure previously reported. The confirmation of the three dimensional nature of the film is unequivocally shown by the infrared absorption band at 1252 cm−1. Temperature programmed desorption was used to show that this three-dimensional thin film covers the Pt(111) surface to such an extent that its application as a catalyst support for clusters/nanoparticles is possible. The growth of a three-dimensional film was seen to be directly correlated with the amount of oxygen present on the surface after the silicon evaporation process. This excess of oxygen is tentatively attributed to atomic oxygen being generated in the evaporator. The identification of atomic oxygen as a necessary building block for the formation of a three-dimensional thin film opens up new possibilities for thin film growth on metal supports, whereby simply changing the type of oxygen enables thin films with different atomic structures to be synthesized. This is a novel approach to tune the synthesis parameters of thin films to grow a specific structure and expands the options for modeling common amorphous silica supports under ultra high vacuum conditions.

  10. Furosemide Loaded Silica-Lipid Hybrid Microparticles: Formulation Development, in vitro and ex vivo Evaluation.

    Science.gov (United States)

    Sambaraj, Swapna; Ammula, Divya; Nagabandi, Vijaykumar

    2015-09-01

    The main objective of the current research work was to formulate and evaluate furosemide loaded silica lipid hybrid microparticles for improved oral delivery. A novel silica-lipid hybrid microparticulate system is used for enhancing the oral absorption of low solubility and low permeability of (BCS Class IV) drugs. Silica-lipid hybrid microparticles include the drug solubilising effect of dispersed lipids and stabilizing effect of hydrophilic silica particles to increase drug solubilisation, which leads to enhanced oral bioavailability. The slica lipid hybrid (SLH) microparticles were composed of poorly soluble drug (furosemide), dispersion of oil phase (Soya bean oil and miglyol) in lecithin (Phospholipoid 90H), non-ionic surfactant (Polysorbate 80) and adsorbent (Aerosol 380). Saturation solubility studies were performed in different oils and surfactants with increased concentration of drug revealed increased solubility of furosemide. In vitro dissolution studies conducted under simulated gastric medium revealed 2-4 fold increase in dissolution efficiencies for SLH microparticles compared to that of pure drug (furosemide) and marketed formulation Lasix®. Ex vivo studies showed enhanced lipid digestibility, which improved drug permeability. Solid-state characterization of SLH microparticles by X-ray powder diffraction and Fourier transform infrared spectroscopic analysis confirmed non-crystalline nature and more compatibility of furosemide in silica-lipid hybrid microparticles. It can be concluded that the role of lipids and hydrophilic silica based carrier highlighted in enhancing solubility and permeability, and hence the oral bioavailability of poorly soluble drugs.

  11. Liquid phase deposition of silica: Thin films, colloids and fullerenes

    Science.gov (United States)

    Whitsitt, Elizabeth A.

    Little research has been done to explore liquid phase deposition (LPD) of silica on non-planar substrates. This thesis proves that the seeded growth of silica colloids from fullerene and surfactant micelles is possible via LPD, as is the coating of individual single walled carbon nanotubes (SWNTs) and carbon fibers. Working on the premise that a molecular growth mechanism (versus colloidal/gel deposition) is valid for LPD, nanostructured substrates and specific chemical functional groups should act as "seeds," or templates, for silica growth. Seeded growth is confirmed by reactions of the growth solution with a range of surfactants and with materials with distinctive surface moieties. LPD promises lower production costs and environmental impact as compared to present methods of coating technology, because it is an inherently simple process, using low temperatures and inexpensive air-stable reactants. Silica is ubiquitous in materials science. Its applications range from thixotropic additives for paint to gate dielectrics in the semiconductor industry. Nano-structured coatings and thin films are integral in today's electronics industry and will become more vital as the size of electronics shrinks. With the incorporation of nanoparticles in future devices, the ability to deposit quality coatings with finely tuned properties becomes paramount. The methods developed herein have applications in fabricating insulators for use in the future molecular scale electronics industry. Additionally, these silica nanoparticles have applications as templates for use in photonics and fuel cell membrane production and lend strength and durability to composites.

  12. Reversible Surface Properties of Polybenzoxazine/Silica Nanocomposites Thin Films

    Directory of Open Access Journals (Sweden)

    Wei-Chen Su

    2013-01-01

    Full Text Available We report the reversible surface properties (hydrophilicity, hydrophobicity of a polybenzoxazine (PBZ thin film through simple application of alternating UV illumination and thermal treatment. The fraction of intermolecularly hydrogen bonded O–H⋯O=C units in the PBZ film increased after UV exposure, inducing a hydrophilic surface; the surface recovered its hydrophobicity after heating, due to greater O–H⋯N intramolecular hydrogen bonding. Taking advantage of these phenomena, we prepared a PBZ/silica nanocomposite coating through two simple steps; this material exhibited reversible transitions from superhydrophobicity to superhydrophilicity upon sequential UV irradiation and thermal treatment.

  13. Structure and mechanical properties of silica doped zirconia thin films

    Energy Technology Data Exchange (ETDEWEB)

    Uhlmann, Ina, E-mail: uhlmann@ceramics.tu-darmstadt.de [Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Hawelka, Dominik [Fraunhofer Institute for Laser Technology ILT, 52074 Aachen (Germany); Hildebrandt, Erwin [Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany); Pradella, Jens [Merck KGaA Darmstadt, 64293 Darmstadt (Germany); Rödel, Jürgen [Institute of Materials Science, Technische Universität Darmstadt, 64287 Darmstadt (Germany)

    2013-01-01

    Sol–gel based wear resistant coatings are presented as an alternative to existing vapor deposition coatings. The films consist of zirconia which has been doped with 8 wt.% silica. Crack-free single as well as multilayer coatings with thicknesses of 80 and 150 nm, respectively, could be produced after sintering at 1000 °C. The evolution of layer thickness, optical, chemical and mechanical properties during film annealing was investigated by ellipsometry, scanning electron microscopy, thermal gravimetric analysis, Fourier transform infrared spectroscopy, X-ray diffraction, nanoindentation and micro-abrasion. Micro-abrasion has been established as an easy and powerful tool to achieve first comparative abrasion data which could be correlated to hardness, Young's modulus and structure of the films. Above 600 °C a tetragonal, oxide coating with a Young's modulus ranging from 80 to 90 GPa, a hardness from 7 to 8 GPa and an increased abrasion resistance was obtained. The film density reached 4.64 g/cm{sup 3} with the mean refractive index n{sub 550} {sub nm} lying between 1.88 and 1.93. - Highlights: ► Sol–gel zirconia–8 wt.% silica coatings with hardness up to 8 GPa achieved ► Layer thickness as compared by ellipsometry and scanning electron microscopy ► Crack-free multilayer coatings produced up to 150 nm.

  14. Preparation of mesoporous silica films SBA-15 over different substrates

    International Nuclear Information System (INIS)

    Campos, V.O.; Sousa, E.M.B. de; Macedo, W.A.A.

    2010-01-01

    Mesoporous materials have been target of frequent interest due to its wide application possibilities, for example development of gas sensors, catalysis, molecules transportation, pharmaceuticals release, synthesis of auto-organized nanostructures, among others. The possibilities of application are enhanced when such materials are disposed in the form of thin and ultrathin films. In this work the preparation of mesoporous SBA-15 silica films is explored by means of the dipcoating technique of a sol-gel on different substrates (glass slides, stainless steel, copper), using the surfactant poly(ethylene glycol)-block-poly(propylene glycol)- block-poly(ethylene glycol), known as P123, a block copolymer. Synthesis parameters surfactant concentration, aging time and temperature were investigated. In this work we present the morphological and structural characterization of the prepared films, which were obtained using atomic force microscopy and x-ray fluorescence and diffraction. (author)

  15. Micropatterned Silica Films with Nanohydroxyapatite for Y-TZP Implants.

    Science.gov (United States)

    Miranda, R B P; Grenho, L; Carvalho, A; Fernandes, M H; Monteiro, F J; Cesar, P F

    2018-03-01

    This investigation aimed at developing micropatterned silica thin films (MSTFs) containing nanohydroxyapatite (nano-HA) microaggregates that were not completely covered by silica so that they could directly interact with the surrounding cells. The objectives were 1) to evaluate the effect of the presence of 2 films (MSTF with or without nano-HA addition) on the characteristic strength (σ 0 ) and Weibull modulus ( m) of a yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and 2) to evaluate the effect of these 2 films, as applied onto the Y-TZP surface, on the morphology, orientation, and proliferation of MG63 cells. Sol-gel process and soft lithography were used to apply the MSTF onto the Y-TZP specimens. Three experimental groups were produced: Y-TZP, Y-TZP + MSTF, and Y-TZP + MSTF + sprayed nano-HA. All surfaces were characterized by scanning electron microscopy and energy-dispersive X-ray spectroscopy and tested for 4-point flexural strength ( n = 30) in water at 37 °C. Weibull analysis was used to determine m and σ 0 (maximum likelihood method). In vitro biological behavior was performed with human osteoblast-like cells (MG63). Y-TZP was successfully coated with MSFT and MSFT + nano-HA. Scanning electron microscopy micrographs indicated that the microaggregates of nano-HA were not entirely covered by the silica. There was no statistically significant difference among the experimental groups for σ 0 and m. In the groups containing the films, the cells were elongated and aligned along the lines. The MSFT + nano-HA group showed significantly higher cell metabolic activity than that obtained for the Y-TZP group at day 7. This investigation was successful in producing an MSTF containing nano-HA microaggregates that remained exposed to the environment. The developed films did not jeopardize the structural reliability of a commercial Y-TZP, as confirmed by the Weibull statistics. The MG63 cells seeded over the films became elongated and aligned along the

  16. Formulation and characterization of date palm fibers mortar by addition of silica fume

    Science.gov (United States)

    Mokhtari, A.; Kriker, A.; Ouaggad, H.; Merad, N.

    2018-05-01

    This paper presents the results of experimental investigations of the formulated and characterization of date palm fibers mortar by addition of silica fume. The use of addition mineral is widely used in the production of cements through the world. The objective of this work is to bring our contribution to the recovery of local resources in the occurrence vegetable fibers of date palm to weak cost and from renewable source and integrate it in the filled of building. Date palm fiber are from Ouargla town in south of Algeria. Different mortar mixtures were prepared in which the cement was substitute by 10% of silica fume. The mechanical characteristics (compressive and flexural strength) of date palm fibers mortar by treatment of the matrix by the adding of silica fume were examined. The results obtained have shown that the mortar workability as well as the compressive and flexural strength decreases with increasing the silica fume replacement. The results showed that the use of silica fume enabled to evaluate the flexural strength. However, another treatment of fibers and matrix will be recommended for Improved the characteristics.

  17. Positron annihilation studies of mesoporous silica films using a slow positron beam

    International Nuclear Information System (INIS)

    He Chunqing; Muramatsu, Makoto; Ohdaira, Toshiyuki; Kinomura, Atsushi; Suzuki, Ryoichi; Ito, Kenji; Kabayashi, Yoshinori

    2006-01-01

    Positron annihilation lifetime spectra were measured for mesoporous silica films, which were synthesized using triblock copolymer (EO 106 PO 70 EO 106 ) as a structure-directing agent. Different positron lifetime spectra for the deposited and calcined films indicated the formation of meso-structure after calcination, which was confirmed by Fourier transform infrared (FTIR) spectra and field emission-scanning electron microscopy (FE-SEM) observation. Open porosity or pore interconnectivity of a silica film might be evaluated by a two-dimensional positron annihilation lifetime spectrum of an uncapped film. Pore sizes and their distributions in the silica films were found to be affected by thermal treatments

  18. Thermal and Mechanical Properties of Poly(butylene succinate Films Reinforced with Silica

    Directory of Open Access Journals (Sweden)

    Sangviroon Nanthaporn

    2015-01-01

    Full Text Available In recent year, bioplastics have become more popular resulting from the growing concerns on environmental issues and the rising fossil fuel price. However, their applications were limited by its mechanical and thermal properties. The aim of this research is thus to improve mechanical and thermal properties of PBS bioplastic films by reinforcing with silica. Due to the poor interfacial interaction between the PBS matrix and silica, glycidyl methacrylate grafted poly(butylene succinate (PBS-g-GMA was used as a compatibilizer in order to improve the interaction between bioplastic films and filler. PBS-g-GMA was prepared in a twin-screw extruder and analyzed by the FTIR spectrometer. PBS and silica were then mixed in a twin-screw extruder and processed into films by a chill-roll cast extruder. The effects of silica loading on thermal and mechanical properties of the prepared bioplastic films were investigated. It was found that the mechanical properties of PBS/silica composite films were improved when 1%wt of silica was added. However, the mechanical properties decreased with increasing silica loading due to the agglomeration of silica particles. The results also show that the silica/PBS films with PBS-g-GMA possessed improved mechanical properties over the films without the compatibilizer.

  19. Ageing-induced enhancement of open porosity of mesoporous silica films studied by positron annihilation spectroscopy

    International Nuclear Information System (INIS)

    He Chunqing; Muramatsu, Makoto; Oshima, Nagayasu; Ohdaira, Toshiyuki; Kinomura, Atsushi; Suzuki, Ryoichi

    2006-01-01

    We show that ageing of the silica sol in a closed vessel enhanced the open porosity of calcined mesoporous silica film studied by positron. Positron annihilation lifetime spectroscopy (PALS) based on a pulsed slow positron beam was used to estimate the mesopore size. 2-dimensional PALS (2D-PALS) and ortho-positronium time-of-flight (Ps-TOF) were used to evaluate the open porosity, interconnectivity and tortuosity of mesopores in the silica films. Results revealed that little change in pore size but significant enhancement of open porosity and/or pore interconnectivity occurred in the silica film deposited after the precursor solution aged for a relative longer time

  20. Influence of p H on optical properties of nano structure sol-gel-derived silica films

    International Nuclear Information System (INIS)

    Heshmatpuor, F.; Adelkhani, H.; Nahavandi, M.; Noorbakhsh Shourabadi, M.

    2006-01-01

    Sol-gel derived silica films were fabricated by dip-coating onto glass microscope substrates. Film properties such as transmission and surface morphology were monitored as function of dip speed and sol p H. Film transmission was increased with increasing of p H in visible range. The surface morphology of films were investigated with scanning electron microscopy.

  1. Tunable pores in mesoporous silica films studied using a pulsed slow positron beam

    International Nuclear Information System (INIS)

    He Chunqing; Muramatsu, Makoto; Ohdaira, Toshiyuki; Oshima, Nagayasu; Kinomura, Atsushi; Suzuki, Ryoichi; Kobayashi, Yoshinori

    2007-01-01

    Positron annihilation lifetime spectroscopy (PALS) based on a pulsed slow positron beam was applied to study mesoporous silica films, synthesized using amphiphilic PEO-PPO-PEO triblock copolymers as structure-directing agents. The pore size depends on the loading of different templates. Larger pores were formed in silica films templated by copolymers with higher molecular-weights. Using 2-dimensional PALS, open porosity of silica films was also found to be influenced by the molecular-weight as well as the ratio of hydrophobic PPO moiety of the templates

  2. Design of a superhydrophobic and superoleophilic film using cured fluoropolymer@silica hybrid

    International Nuclear Information System (INIS)

    Yang, Hao; Pi, Pihui; Yang, Zhuo-ru; Lu, Zhong; Chen, Rong

    2016-01-01

    Graphical abstract: - Highlights: • Cured fluoropolymer@silica hybrid was coated on stainless steel mesh. • The hybrid film showed superhydrophobicity and superoleophilicity by adjusting silica dosage. • The hybrid film exhibited good thermal stability and excellent oil/water separation efficiency. - Abstract: Recently, considerable efforts have been made on superhydrophobic–superoleophilic filter to satisfy the requirements of the applications to oil/water separation. In this work, we obtained a superhydrophobic and superoleophilic film by coating cured fluoropolymer@silica hybrid on stainless steel mesh. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric-differential scanning calorimetry (TG-DSC) were used to determine the chemical composition and thermal stability of the sample. The effect of silica nanoparticles (NPs) concentration on the surface property of the hybrid film was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle analyzer. The results indicate that silica NPs not only enhance the thermal stability, but also strengthen the hydrophobicity and oleophilicity of the film. When 20 wt% silica NPs was added into the thermosetting fluoropolymer, the hybrid film shows both superhydrophobicity and superoleophilicity owing to the large surface roughness factor (RMS) and porous structure. Moreover, the hybrid film could be used to separate water from different oils effectively. When the pore size of the mesh is less than 300 μm, the oil/water separation efficiency of the film reaches above 99%, which shows a great potential application to dehydrate fuel oils.

  3. Design of a superhydrophobic and superoleophilic film using cured fluoropolymer@silica hybrid

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Hao [Key Laboratory for Green Chemical Process of Ministry of Education and School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Xiongchu Street, Wuhan, 430073 (China); Pi, Pihui; Yang, Zhuo-ru [School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, 510640 (China); Lu, Zhong [Key Laboratory for Green Chemical Process of Ministry of Education and School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Xiongchu Street, Wuhan, 430073 (China); Chen, Rong, E-mail: rchenhku@hotmail.com [Key Laboratory for Green Chemical Process of Ministry of Education and School of Chemistry and Environmental Engineering, Wuhan Institute of Technology, Xiongchu Street, Wuhan, 430073 (China)

    2016-12-01

    Graphical abstract: - Highlights: • Cured fluoropolymer@silica hybrid was coated on stainless steel mesh. • The hybrid film showed superhydrophobicity and superoleophilicity by adjusting silica dosage. • The hybrid film exhibited good thermal stability and excellent oil/water separation efficiency. - Abstract: Recently, considerable efforts have been made on superhydrophobic–superoleophilic filter to satisfy the requirements of the applications to oil/water separation. In this work, we obtained a superhydrophobic and superoleophilic film by coating cured fluoropolymer@silica hybrid on stainless steel mesh. Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric-differential scanning calorimetry (TG-DSC) were used to determine the chemical composition and thermal stability of the sample. The effect of silica nanoparticles (NPs) concentration on the surface property of the hybrid film was analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and contact angle analyzer. The results indicate that silica NPs not only enhance the thermal stability, but also strengthen the hydrophobicity and oleophilicity of the film. When 20 wt% silica NPs was added into the thermosetting fluoropolymer, the hybrid film shows both superhydrophobicity and superoleophilicity owing to the large surface roughness factor (RMS) and porous structure. Moreover, the hybrid film could be used to separate water from different oils effectively. When the pore size of the mesh is less than 300 μm, the oil/water separation efficiency of the film reaches above 99%, which shows a great potential application to dehydrate fuel oils.

  4. Preparation and Characterization of Silica/Polyamide-imide Nanocomposite Thin Films

    Directory of Open Access Journals (Sweden)

    Hwang Jong-Sun

    2010-01-01

    Full Text Available Abstract The functional silica/polyamide-imide composite films were prepared via simple ultrasonic blending, after the silica nanoparticles were modified by cationic surfactant—cetyltrimethyl ammonium bromide (CTAB. The composite films were characterized by scanning electron microscope (SEM, thermo gravimetric analysis (TGA and thermomechanical analysis (TMA. CTAB-modified silica nanoparticles were well dispersed in the polyamide-imide matrix, and the amount of silica nanoparticles to PAI was investigated to be from 2 to 10 wt%. Especially, the coefficients of thermal expansion (CET continuously decreased with the amount of silica particles increasing. The high thermal stability and low coefficient of thermal expansion showed that the nanocomposite films can be widely used in the enamel wire industry.

  5. Physical Characteristics of Chitosan Based Film Modified With Silica and Polyethylene Glycol

    Directory of Open Access Journals (Sweden)

    F. Widhi Mahatmanti

    2014-07-01

    Full Text Available Recently, development of film materials is focused on finding the films with high chemical and physical stabilities. Organic based material such as chitosan produces films with low physical stability, and hence addition of inorganic materials necessary. In this research, the effect of silica and polyethylene glycol (PEG addition on the properties of chitosan based films has been investigated. Precursors used to produce films included chitosan with the deacetylation degree of 83% and sodium silicate solution as the silica source. A simple synthesis in a one-pot process was carried out by mixing 1%(w of chitosan solution in 2%(v/v acetate acid and sodium silicate solution (27% SiO2 in various composition ratios and casting the solution on a glass dish. The tensile strength and percentage of elongation decrease with increasing the silica content. The tensile strength tends to decline with addition of PEG, but the elongation percentage of the film increases. Hydrophilicity of the film decreases with the addition of silica and increases with the addition of PEG. The addition of silica and PEG does not change significantly the morphology of the film and functional groups indicating the domination of physical interaction among active sites in the film components.

  6. Gold Incorporated Mesoporous Silica Thin Film Model Surface as a Robust SERS and Catalytically Active Substrate

    Directory of Open Access Journals (Sweden)

    Anandakumari Chandrasekharan Sunil Sekhar

    2016-05-01

    Full Text Available Ultra-small gold nanoparticles incorporated in mesoporous silica thin films with accessible pore channels perpendicular to the substrate are prepared by a modified sol-gel method. The simple and easy spin coating technique is applied here to make homogeneous thin films. The surface characterization using FESEM shows crack-free films with a perpendicular pore arrangement. The applicability of these thin films as catalysts as well as a robust SERS active substrate for model catalysis study is tested. Compared to bare silica film our gold incorporated silica, GSM-23F gave an enhancement factor of 103 for RhB with a laser source 633 nm. The reduction reaction of p-nitrophenol with sodium borohydride from our thin films shows a decrease in peak intensity corresponding to –NO2 group as time proceeds, confirming the catalytic activity. Such model surfaces can potentially bridge the material gap between a real catalytic system and surface science studies.

  7. Improvement of RVNRL film properties by adding fumed silica and hydroxy apatite

    Directory of Open Access Journals (Sweden)

    Adul Thiangchanya

    2003-01-01

    Full Text Available The effect of adding fumed silica and hydroxy apatite to Radiation Vulcanized Natural Rubber Latex (RVNRL for improving tear strength, aging properties, degradability and water-soluble protein content of rubber films has been investigated. The addition of fumed silica and hydroxy apatite in RVNRL improves tear strength and aging properties of rubber films, whereas tensile strength and degradability of rubber films were unchanged during storage at room temperature. The water-soluble protein content in rubber films was reduced by immobilization of the fumed silica and hydroxy apatite and enhanced by addition of ZnO. This may reduce allergy problems of natural rubber latex products caused by water-soluble protein. The MST of the RVNRL with fumed silica and hydroxy apatite indicated that the latex must be used within two months after mixing because of its stability.

  8. A Robust Fiber Bragg Grating Hydrogen Gas Sensor Using Platinum-Supported Silica Catalyst Film

    OpenAIRE

    Marina Kurohiji; Seiji Ichiriyama; Naoki Yamasaku; Shinji Okazaki; Naoya Kasai; Yusuke Maru; Tadahito Mizutani

    2018-01-01

    A robust fiber Bragg grating (FBG) hydrogen gas sensor for reliable multipoint-leakage monitoring has been developed. The sensing mechanism is based on shifts of center wavelength of the reflection spectra due to temperature change caused by catalytic combustion heat. The sensitive film which consists of platinum-supported silica (Pt/SiO2) catalyst film was obtained using sol-gel method. The precursor solution was composed of hexachloroplatinic acid and commercially available silica precursor...

  9. Persistent superhydrophilicity of sol-gel derived nanoporous silica thin films

    International Nuclear Information System (INIS)

    Ganjoo, S; Azimirad, R; Akhavan, O; Moshfegh, A Z

    2009-01-01

    In this investigation, sol-gel synthesized nanoporous silica thin films, annealed at different temperatures, with long time superhydrophilic property have been studied. Two kinds of sol-gel silica thin films were fabricated by dip-coating of glass substrates in two different solutions; with low and high water. The transparent coated films were dried at 100 deg. C and then annealed in a temperature range of 200-500 deg. C. The average water contact angle of the silica films prepared with low water content and annealed at 300 deg. C measured about 5 deg. for a long time (6 months) without any UV irradiation. Instead, adding water into the sol resulted in silica films with an average water contact angle greater than 60 deg. Atomic force microscopic analysis revealed that the silica films prepared with low water had a rough surface (∼30 nm), while the films prepared with high water had a smoother surface (∼2 nm). Using x-ray photoelectron spectroscopy, we have shown that with a decrease in the surface water on the film, its hydrophilicity increases logarithmically.

  10. Silica frit formulation for low temperature co-fired ceramic tapes (LTCC)

    International Nuclear Information System (INIS)

    Nor Hayati Alias; Che Seman Mahmood

    2006-01-01

    Glassifier agents or so called fluxes could function to lower down the melting temperature of a ceramic material. Two types of silica based glass frits have been formulated to undergo vitrification at temperature lower than 1000 degree C. Frit A powder is composing of 11% Sodium Carbonate, 11% Calcium Oxide,15% Plumbum Oxide and 10% MgO while Frit B is composing of 12% Boron Oxide, 5% Ceria, 11% Sodium Carbonate and 2% Magnesium Oxide as glassifier agent in Silica powder. Two different ceramic slurries were made from a-alumina powder with addition of either Frit A or Frit B and also dispersant, binder and plasticizers, followed by casting into 0.04 mm thickness alumina green tapes. The tapes were then fired at temperature 1000 degree C to burn out plastic binder system and to vitrify the glass frits. Scanning Electron Microscopy (SEM)/EDX techniques were carried out to observe the changes in microstructure of the tape due to vitrication of glass frits. Comparisons were made with alumina green tapes without any glass frit component and with Commercial LTCC DuPont 951 tape. (Author)

  11. Hybrid thin films derived from UV-curable acrylate-modified waterborne polyurethane and monodispersed colloidal silica

    Directory of Open Access Journals (Sweden)

    C. H. Yang

    2012-01-01

    Full Text Available Hybrid thin films containing nano-sized inorganic domains were synthesized from UV-curable acrylate-modified waterborne polyurethane (WPU-AC and monodispersed colloidal silica with coupling agent. The coupling agent, 3-(trimethoxysilylpropyl methacrylate (MSMA, was bonded onto colloidal silica first, and then mixed with WPU-AC to form a precursor solution. This precursor was spin coated, dried and UV-cured to generate the hybrid films. The silica content in the hybrid thin films was varied from 0 to 30 wt%. Experimental results showed the aggregation of silica particles in the hybrid films. Thus, the silica domain in the hybrid films was varied from 30 to 50 nm by the different ratios of MSMAsilica to WPU-AC. The prepared hybrid films from the crosslinked WPU-AC/MSMA-silica showed much better thermal stability and mechanical properties than pure WPU-AC.

  12. Molecular-dynamics simulations of thin polyisoprene films confined between amorphous silica substrates

    International Nuclear Information System (INIS)

    Guseva, D. V.; Komarov, P. V.; Lyulin, Alexey V.

    2014-01-01

    Constant temperature–constant pressure (NpT) molecular-dynamics computer simulations have been carried out for the united-atom model of a non-crosslinked (1,4) cis-polyisoprene (PI) melt confined between two amorphous, fully coordinated silica surfaces. The Lennard-Jones 12-6 potential was implemented to describe the polymer–silica interactions. The thickness H of the produced PI–silica film has been varied in a wide range, 1 g g is the individual PI chain radius of gyration measured under the imposed confinement. After a thorough equilibration, the PI film stratified structure and polymer segmental dynamics have been studied. The chain structure in the middle of the films resembles that in a corresponding bulk, but the polymer-density profile shows a pronounced ordering of the polymer segments in the vicinity of silica surfaces; this ordering disappears toward the film middles. Tremendous slowing down of the polymer segmental dynamics has been observed in the film surface layers, with the segmental relaxation more than 150 times slower as compared to that in a PI bulk. This effect increases with decreasing the polymer-film thickness. The segmental relaxation in the PI film middles shows additional relaxation process which is absent in a PI bulk. Even though there are fast relaxation processes in the film middle, its overall relaxation is slower as compared to that in a bulk sample. The interpretation of the results in terms of polymer glassy bridges has been discussed

  13. Preparing hydrophobic nanocellulose-silica film by a facile one-pot method.

    Science.gov (United States)

    Le, Duy; Kongparakul, Suwadee; Samart, Chanatip; Phanthong, Patchiya; Karnjanakom, Surachai; Abudula, Abuliti; Guan, Guoqing

    2016-11-20

    Hydrophobic nanocellulose-silica film was successfully prepared by a facile one-pot method using tetraethoxysilane (TEOS) and dodecyl triethoxylsilane (DTES). Morphological characterization of the hydrophobic nanocellulose-silica (NC-SiO2-DTES) film showed well self-assembled DTES modified silica spherical nanoparticles with the particle sizes in the range of 88-126nm over the nanocellulose film. The hydrophobicity of the NC-SiO2-DTES film was achieved owing to the improvement of roughness of the nanocellulose film by coating dodecyl- terminated silica nanoparticles. An increase in DTES loading amount and reaction time increased the hydrophobicity of the film, and the optimum condition for NC-SiO2-DTES film preparation was achieved at DTES/TEOS molar ratio of 2.0 for 8h reaction time. Besides, the NC-SiO2-DTES film performed superoleophilic property with octane and hexadecane contact angles of 0°. It also showed an excellent hydrophobic property over all pH values ranged from 1 to 14. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Mesoporous silica films as catalyst support for microstructured reactors: preparation and characterization

    NARCIS (Netherlands)

    Muraza, O.; Kooyman, P.J.; Lafont, U.; Albouy, P.A.; Khimyak, T.; Rebrov, E.V.; Croon, de M.H.J.M.; Schouten, J.C.

    2008-01-01

    Mesoporous silica thin films with hexagonal and cubic mesostructure have been deposited by the evaporation induced self-assembly assisted sol–gel route on microchannels etched in a Pyrex® 7740 borosilicate glass substrate. Prior to the synthesis, a 50 nm TiO2 film has been deposited on the substrate

  15. Photochemical oxygen reduction by zinc phthalocyanine and silver/gold nanoparticle incorporated silica thin films

    Energy Technology Data Exchange (ETDEWEB)

    Pal, Manas; Ganesan, Vellaichamy, E-mail: velganesh@yahoo.com; Azad, Uday Pratap

    2012-12-15

    Silver or gold nanoparticles are synthesized using a borohydride reduction method and are anchored simultaneously into/onto the mercaptopropyl functionalized silica. Later, zinc phthalocyanine is adsorbed onto the above materials. Thin films of these materials are prepared by coating an aqueous colloidal suspension of the respective material onto glass plates. Visible light irradiation of these films in oxygen saturated, stirred aqueous solutions effectively reduces oxygen to hydrogen peroxide. The photocatalytic reduction of oxygen is explained on the basis of the semiconducting properties of the silica films. The back electron transfer reaction is largely prevented by means of a sacrificial electron donor, triethanolamine. - Highlights: Black-Right-Pointing-Pointer Zinc phthalocyanine adsorbed silica materials were prepared. Black-Right-Pointing-Pointer Thin films of these materials photocatalytically reduce oxygen. Black-Right-Pointing-Pointer The photocatalysis is explained based on semiconductor properties of the materials. Black-Right-Pointing-Pointer Metal nanoparticles increase the photocatalytic efficiency of the materials.

  16. Silica-Coated Liposomes for Insulin Delivery

    Directory of Open Access Journals (Sweden)

    Neelam Dwivedi

    2010-01-01

    Full Text Available Liposomes coated with silica were explored as protein delivery vehicles for their enhanced stability and improved encapsulation efficiency. Insulin was encapsulated within the fluidic phosphatidylcholine lipid vesicles by thin film hydration at pH 2.5, and layer of silica was formed above lipid bilayer by acid catalysis. The presence of silica coating and encapsulated insulin was identified using confocal and electron microscopy. The native state of insulin present in the formulation was evident from Confocal Micro-Raman spectroscopy. Silica coat enhances the stability of insulin-loaded delivery vehicles. In vivo study shows that these silica coated formulations were biologically active in reducing glucose levels.

  17. Sol-gel-derived mesoporous silica films with low dielectric constants

    Energy Technology Data Exchange (ETDEWEB)

    Seraji, S.; Wu, Yun; Forbess, M.; Limmer, S.J.; Chou, T.; Cao, Guozhong [Washington Univ., Seattle, WA (United States). Dept. of Materials Science and Engineering

    2000-11-16

    Mesoporous silica films with low dielectric constants and possibly closed pores have been achieved with a multiple step sol-gel processing technique. Crack-free films with approximately 50% porosity and 0.9 {mu}m thicknesses were obtained, a tape-test revealing good adhesion between films and substrates or metal electrodes. Dielectric constants remained virtually unchanged after aging at room temperature at 56% humidity over 6 days. (orig.)

  18. A simple three step method for selective placement of organic groups in mesoporous silica thin films

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, Esteban A. [Gerencia Química, Centro Atómico Constituyentes, Comisión Nacional de Energía Atómica, Av. Gral Paz 1499 (B1650KNA) San Martín, Buenos Aires (Argentina); Llave, Ezequiel de la; Williams, Federico J. [Departamento de Química Inorgánica, Analítica y Química Física and INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, C1428EHA Buenos Aires (Argentina); Soler-Illia, Galo J.A.A., E-mail: galo.soler.illia@gmail.com [Departamento de Química Inorgánica, Analítica y Química Física and INQUIMAE-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellón II, C1428EHA Buenos Aires (Argentina); Instituto de Nanosistemas, Universidad Nacional de General San Martín, 25 de Mayo y Francia (1650) San Martín, Buenos Aires (Argentina)

    2016-02-01

    Selective functionalization of mesoporous silica thin films was achieved using a three step method. The first step consists in an outer surface functionalization, followed by washing off the structuring agent (second step), leaving the inner surface of the pores free to be functionalized in the third step. This reproducible method permits to anchor a volatile silane group in the outer film surface, and a second type of silane group in the inner surface of the pores. As a concept test we modified the outer surface of a mesoporous silica film with trimethylsilane (–Si–(CH{sub 3}){sub 3}) groups and the inner pore surface with propylamino (–Si–(CH{sub 2}){sub 3}–NH{sub 2}) groups. The obtained silica films were characterized by Environmental Ellipsometric Porosimetry (EEP), EDS, XPS, contact angle and electron microscopy. The selectively functionalized silica (SF) shows an amount of surface amino functions 4.3 times lower than the one-step functionalized (OSF) silica samples. The method presented here can be extended to a combination of silane chlorides and alkoxides as functional groups, opening up a new route toward the synthesis of multifunctional mesoporous thin films with precisely localized organic functions. - Highlights: • Selective functionalization of mesoporous silica thin films was achieved using a three step method. • A volatile silane group is anchored by evaporation on the outer film surface. • A second silane is deposited in the inner surface of the pores by post-grafting. • Contact angle, EDS and XPS measurements show different proportions of amino groups on both surfaces. • This method can be extended to a combination of silane chlorides and alkoxides functional groups.

  19. Preparation and Properties of Nano Dy/TiO2 Films Supported on High Silica Fiber

    Directory of Open Access Journals (Sweden)

    HUANG Feng-ping

    2017-07-01

    Full Text Available In order to improve the photocatalytic degradation performance and stability of nano TiO2, Dy doped TiO2 supported on high silica glass fiber was prepared by microwave-sol method combined with dip-coating method. The samples were analyzed by XRD,SEM,PL,EDS,XPS and other equipments for phase composition of films,surface topography, surface elements and the stability of films. And the effects of pretreatment solution and coating method on the high-silica fiber film were investigated.In addition, the photocatalytic performance of the sample has been investigated by degrading methylene blue. The results show that the catalytic stability of Dy doping TiO2 nanofilms supported on high silica glass fiber can be improved and the degradation of methyl orange can reach 94% in 30min after 5 times of coating treatment.

  20. Formulation and Characterization of Acetaminophen Nanoparticles in Orally Disintegrating Films

    Science.gov (United States)

    AI-Nemrawi, Nusaiba K.

    The purpose of this study is to prepare acetaminophen loaded nanoparticles to be cast directly, while still in the emulsion form, into Orally Disintegrating Films (ODF). By casting the nanoparticles in the films, we expected to keep the particles in a stable form where the nanoparticles would be away from each other to prevent their aggregation. Once the films are applied on the buccal mucosa, they are supposed to dissolve within seconds, releasing the nanoparticles. Then the nanoparticles could be directly absorbed through the mucosa to the blood stream and deliver acetaminophen there. The oral cavity mucosa is one of the most attractive sites for systemic drug delivery due to its high permeability and blood supply. Furthermore, it is robust and shows short recovery times after stress or damage, and the drug bypasses first pass effect and avoids presystemic elimination in the GI tract. Nanoencapsulation increases drug efficacy, specificity, tolerability and therapeutic index. These Nanocapsules have several advantages in the protection of premature degradation and interaction with the biological environment, enhancement of absorption into a selected tissue, bioavailability, retention time and improvement of intracellular penetration. The most important characteristics of nanoparticles are their size, encapsulation efficiency (EE), zeta potential (surface charge), and the drug release profiles. Unfortunately, nanoparticles tend to precipitate or aggregate into larger particles within a short time after preparation or during storage. Some solutions for this problem were mentioned in literature including lyophilization and spray drying. These methods are usually expensive and give partial solutions that might have secondary problems; such as low re-dispersion efficacy of the lyophilized NPs. Furthermore, most of the formulations of NPs are invasive or topical. Few formulas are available to be given orally. Fast disintegrating films (ODFs) are rapidly gaining interest

  1. Molecular insight into nanoscale water films dewetting on modified silica surfaces.

    Science.gov (United States)

    Zhang, Jun; Li, Wen; Yan, Youguo; Wang, Yefei; Liu, Bing; Shen, Yue; Chen, Haixiang; Liu, Liang

    2015-01-07

    In this work, molecular dynamics simulations are adopted to investigate the microscopic dewetting mechanism of nanoscale water films on methylated silica surfaces. The simulation results show that the dewetting process is divided into two stages: the appearance of dry patches and the quick contraction of the water film. First, the appearance of dry patches is due to the fluctuation in the film thickness originating from capillary wave instability. Second, for the fast contraction of water film, the unsaturated electrostatic and hydrogen bond interactions among water molecules are the driving forces, which induce the quick contraction of the water film. Finally, the effect of film thickness on water films dewetting is studied. Research results suggest that upon increasing the water film thickness from 6 to 8 Å, the final dewetting patterns experience separate droplets and striation-shaped structures, respectively. But upon further increasing the water film thickness, the water film is stable and there are no dry patches. The microscopic dewetting behaviors of water films on methylated silica surfaces discussed here are helpful in understanding many phenomena in scientific and industrial processes better.

  2. Biodegradable Starch/Copolyesters Film Reinforced with Silica Nanoparticles: Preparation and Characterization

    Science.gov (United States)

    Lima, Roberta A.; Oliveira, Rene R.; Wataya, Célio H.; Moura, Esperidiana A. B.

    Biodegradable starch/copolyesters/silica nanocomposite films were prepared by melt extrusion, using a twin screw extruder machine and blown extrusion process. The influence of the silica nanoparticle addition on mechanical and thermal properties of nanocomposite films was investigated by tensile tests; X-rays diffraction (XRD), differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM) analysis and the correlation between properties was discussed. The results showed that incorporation of 2 % (wt %) of SiO2 nanoparticle in the blend matrix of PBAT/Starch, resulted in a gain of mechanical properties of blend.

  3. Atomic Structure Control of Silica Thin Films on Pt(111)

    KAUST Repository

    Crampton, Andrew S; Ridge, Claron J.; Rö tzer, Marian David; Zwaschka, Gregor; Braun, Thomas; D'Elia, Valerio; Basset, Jean-Marie; Schweinberger, Florian Frank; Gü nther, Sebastian; Heiz, Ueli

    2015-01-01

    Metal oxide thin films grown on metal single crystals are commonly used to model heterogeneous catalyst supports. The structure and properties of thin silicon dioxide films grown on metal single crystals have only recently been thoroughly

  4. High-coercivity FePt nanoparticle assemblies embedded in silica thin films

    International Nuclear Information System (INIS)

    Yan, Q; Purkayastha, A; Singh, A P; Li, H; Ramanath, G; Li, A; Ramanujan, R V

    2009-01-01

    The ability to process assemblies using thin film techniques in a scalable fashion would be a key to transmuting the assemblies into manufacturable devices. Here, we embed FePt nanoparticle assemblies into a silica thin film by sol-gel processing. Annealing the thin film composite at 650 deg. C transforms the chemically disordered fcc FePt phase into the fct phase, yielding magnetic coercivity values H c >630 mT. The positional order of the particles is retained due to the protection offered by the silica host. Such films with assemblies of high-coercivity magnetic particles are attractive for realizing new types of ultra-high-density data storage devices and magneto-composites.

  5. Secondary electron emission yield on poled silica based thick films

    DEFF Research Database (Denmark)

    Braga, D.; Poumellec, B.; Cannas, V.

    2004-01-01

    Studies on the distribution of the electric field produced by a thermal poling process in a layer of Ge-doped silica on silicon substrate, by using secondary electron emission yield (SEEY) measurements () are presented. Comparing 0 between poled and unpoled areas, the SEEY at the origin of electr...

  6. Low temperature mechanical dissipation of an ion-beam sputtered silica film

    International Nuclear Information System (INIS)

    Martin, I W; Craig, K; Bassiri, R; Hough, J; Robie, R; Rowan, S; Nawrodt, R; Schwarz, C; Harry, G; Penn, S; Reid, S

    2014-01-01

    Thermal noise arising from mechanical dissipation in oxide mirror coatings is an important limit to the sensitivity of future gravitational wave detectors, optical atomic clocks and other precision measurement systems. Here, we present measurements of the temperature dependence of the mechanical dissipation of an ion-beam sputtered silica film between 10 and 300 K. A dissipation peak was observed at 20 K and the low temperature dissipation was found to have significantly different characteristics than observed for bulk silica and silica films deposited by alternative techniques. These results are important for better understanding the underlying mechanisms of mechanical dissipation, and thus thermal noise, in the most commonly-used reflective coatings for precision measurements. (paper)

  7. Biomimetic Cationic Nanoparticles Based on Silica: Optimizing Bilayer Deposition from Lipid Films

    Directory of Open Access Journals (Sweden)

    Rodrigo T. Ribeiro

    2017-10-01

    Full Text Available The optimization of bilayer coverage on particles is important for a variety of biomedical applications, such as drug, vaccine, and genetic material delivery. This work aims at optimizing the deposition of cationic bilayers on silica over a range of experimental conditions for the intervening medium and two different assemblies for the cationic lipid, namely, lipid films or pre-formed lipid bilayer fragments. The lipid adsorption on silica in situ over a range of added lipid concentrations was determined from elemental analysis of carbon, hydrogen, and nitrogen and related to the colloidal stability, sizing, zeta potential, and polydispersity of the silica/lipid nanoparticles. Superior bilayer deposition took place from lipid films, whereas adsorption from pre-formed bilayer fragments yielded limiting adsorption below the levels expected for bilayer adsorption.

  8. Addition of silica nanoparticles to tailor the mechanical properties of nanofibrillated cellulose thin films.

    Science.gov (United States)

    Eita, Mohamed; Arwin, Hans; Granberg, Hjalmar; Wågberg, Lars

    2011-11-15

    Over the last decade, the use of nanocellulose in advanced technological applications has been promoted both due the excellent properties of this material in combination with its renewability. In this study, multilayered thin films composed of nanofibrillated cellulose (NFC), polyvinyl amine (PVAm) and silica nanoparticles were fabricated on polydimethylsiloxane (PDMS) using a layer-by-layer adsorption technique. The multilayer build-up was followed in situ by quartz crystal microbalance with dissipation, which indicated that the PVAm-SiO(2)-PVAm-NFC system adsorbs twice as much wet mass material compared to the PVAm-NFC system for the same number of bilayers. This is accompanied with a higher viscoelasticity for the PVAm-SiO(2)-PVAm-NFC system. Ellipsometry indicated a dry-state thickness of 2.2 and 3.4 nm per bilayer for the PVAm-NFC system and the PVAm-SiO(2)-PVAm-NFC system, respectively. Atomic force microscopy height images indicate that in both systems, a porous network structure is achieved. Young's modulus of these thin films was determined by the Strain-Induced Elastic Buckling Instability for Mechanical Measurements (SIEBIMM) technique. The Young's modulus of the PVAm/NFC films was doubled, from 1 to 2 GPa, upon incorporation of silica nanoparticles in the films. The introduction of the silica nanoparticles lowered the refractive index of the films, most probably due to an increased porosity of the films. Copyright © 2011 Elsevier Inc. All rights reserved.

  9. Defect prevention in silica thin films synthesized using AP-PECVD for flexible electronic encapsulation

    NARCIS (Netherlands)

    Elam, F.M.; Starostin, S.A.; Meshkova, A.S.; Van Der Velden-Schuermans, B.C.A.M.; Van De Sanden, M.C.M.; De Vries, H.W.

    2017-01-01

    Industrially and commercially relevant roll-to-roll atmospheric pressure-plasma enhanced chemical vapour deposition was used to synthesize smooth, 80 nm silica-like bilayer thin films comprising a dense 'barrier layer' and comparatively porous 'buffer layer' onto a flexible polyethylene 2,6

  10. Phosphorus-doped thin silica films characterized by magic-angle spinning nuclear magnetic resonance spectroscopy

    DEFF Research Database (Denmark)

    Jacobsen, H.J.; Skibsted, J.; Kristensen, Martin

    2001-01-01

    Magic-angle spinning nuclear magnetic resonance spectra of 31P and 29Si have been achieved for a thin silica film doped with only 1.8% 31P and deposited by plasma enhanced chemical vapor deposition on a pure silicon wafer. The observation of a symmetric 31P chemical shift tensor is consistent...

  11. Spin-on nanostructured silicon-silica film displaying room-temperature nanosecond lifetime photoluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Y.; Hatton, B.; Miguez, H.; Coombs, N.; Fournier-Bidoz, S.; Ozin, G.A. [Materials Chemistry Research Group, Department of Chemistry, Lash Miller Chemical Laboratories, University of Toronto, 80 St. George Street, Toronto, Ontario, M5S 3H6 (Canada); Grey, J.K.; Beaulac, R.; Reber, C. [Department of Chemistry, University of Montreal, Montreal, Quebec H3C 3J7 (Canada)

    2003-04-17

    A yellow transparent mesoporous silica film has been achieved by the incorporation of silicon nanoclusters into its channels. The resulting nanocomposite - fabricated using a combination of evaporation induced self- assembly and chemical vapor deposition - emits light brightly at visible wavelengths and has nanosecond radiative lifetimes at room temperature when excited by ultraviolet light (see Figure). (Abstract Copyright [2003], Wiley Periodicals, Inc.)

  12. Defect prevention in silica thin films synthesized using AP-PECVD for flexible electronic encapsulation

    NARCIS (Netherlands)

    Elam, F. M.; Starostin, S. A.; Meshkova, A. S.; van der Velden, B. C. A. M.; van de Sanden, M. C. M.; de Vries, H. W.

    2017-01-01

    Industrially and commercially relevant roll-to-roll atmospheric pressure-plasma enhanced chemical vapour deposition was used to synthesize smooth, 80 nm silica-like bilayer thin films comprising a dense ‘barrier layer’ and comparatively porous ‘buffer layer’ onto a flexible polyethylene 2,6

  13. Dielectric breakdown in silica-amorphous polymer nanocomposite films: the role of the polymer matrix.

    Science.gov (United States)

    Grabowski, Christopher A; Fillery, Scott P; Westing, Nicholas M; Chi, Changzai; Meth, Jeffrey S; Durstock, Michael F; Vaia, Richard A

    2013-06-26

    The ultimate energy storage performance of an electrostatic capacitor is determined by the dielectric characteristics of the material separating its conductive electrodes. Polymers are commonly employed due to their processability and high breakdown strength; however, demands for higher energy storage have encouraged investigations of ceramic-polymer composites. Maintaining dielectric strength, and thus minimizing flaw size and heterogeneities, has focused development toward nanocomposite (NC) films; but results lack consistency, potentially due to variations in polymer purity, nanoparticle surface treatments, nanoparticle size, and film morphology. To experimentally establish the dominant factors in broad structure-performance relationships, we compare the dielectric properties for four high-purity amorphous polymer films (polymethyl methacrylate, polystyrene, polyimide, and poly-4-vinylpyridine) incorporating uniformly dispersed silica colloids (up to 45% v/v). Factors known to contribute to premature breakdown-field exclusion and agglomeration-have been mitigated in this experiment to focus on what impact the polymer and polymer-nanoparticle interactions have on breakdown. Our findings indicate that adding colloidal silica to higher breakdown strength amorphous polymers (polymethyl methacrylate and polyimide) causes a reduction in dielectric strength as compared to the neat polymer. Alternatively, low breakdown strength amorphous polymers (poly-4-vinylpyridine and especially polystyrene) with comparable silica dispersion show similar or even improved breakdown strength for 7.5-15% v/v silica. At ∼15% v/v or greater silica content, all the polymer NC films exhibit breakdown at similar electric fields, implying that at these loadings failure becomes independent of polymer matrix and is dominated by silica.

  14. Hydrophobicity of silica thin films: The deconvolution and interpretation by Fourier-transform infrared spectroscopy

    Science.gov (United States)

    Saputra, Riza Eka; Astuti, Yayuk; Darmawan, Adi

    2018-06-01

    This work investigated the synthesis of dimethoxydimethylsilane:tetraethoxysilane (DMDMS:TEOS) silica thin films as well as the effect of DMDMS:TEOS molar ratios and calcination temperature on hydrophobic properties of silica thin films and its correlation with the FTIR spectra behaviour. The silica thin films were synthesized by sol-gel method using combination of DMDMS and TEOS as silica precursors, ethanol as solvent and ammonia as catalyst, with DMDMS and TEOS molar ratio of 10:90, 25:75, 50:50, 75:25 and 90:10. The results showed that DMDMS:TEOS molar ratio had significant impact on the hydrophobic properties of silica thin films coated on a glass surface. Furthermore, the correlation between water contact angle (WCA) and DMDMS:TEOS molar ratio was found to be in a parabolic shape. Concurrently, the maximum apex of the parabola obtained was observed on the DMDMS:TEOS molar ratio of 50:50 for all calcination temperature. It was clearly observed that the silica xerogel exhibiting notable change in relative peak intensities showed FTIR peak splitting of υasymmetric Si-O-Si. To uncover what happened at the FTIR peak, the deconvolution was conducted in Gaussian approach. It was established that the changes in the Gaussian peak component were related to DMDMS:TEOS molar ratios and the calcination temperature that allowed us to tailor the DMDMS:TEOS silica polymer structure model based on the peak intensity ratios. With the increase of DMDMS:TEOS molar ratio, the ratio of (cyclic Si-O-Si)/(linear Si-O-Si) decreased, whilst the ratio of (C-H)/(linear Si-O-Si) increased. Both ratios intersected at DMDMS:TEOS molar ratio of 50:50 with contribution factor ratio of 1:16 and 1:50 for silica xerogel calcined at 300 °C and 500 °C respectively. The importance of this research is the DMDMS:TEOS molar ratio plays an important role in determining the hydrophobic properties of thin films.

  15. Hydrophobicity of silica thin films: The deconvolution and interpretation by Fourier-transform infrared spectroscopy.

    Science.gov (United States)

    Saputra, Riza Eka; Astuti, Yayuk; Darmawan, Adi

    2018-03-14

    This work investigated the synthesis of dimethoxydimethylsilane:tetraethoxysilane (DMDMS:TEOS) silica thin films as well as the effect of DMDMS:TEOS molar ratios and calcination temperature on hydrophobic properties of silica thin films and its correlation with the FTIR spectra behaviour. The silica thin films were synthesized by sol-gel method using combination of DMDMS and TEOS as silica precursors, ethanol as solvent and ammonia as catalyst, with DMDMS and TEOS molar ratio of 10:90, 25:75, 50:50, 75:25 and 90:10. The results showed that DMDMS:TEOS molar ratio had significant impact on the hydrophobic properties of silica thin films coated on a glass surface. Furthermore, the correlation between water contact angle (WCA) and DMDMS:TEOS molar ratio was found to be in a parabolic shape. Concurrently, the maximum apex of the parabola obtained was observed on the DMDMS:TEOS molar ratio of 50:50 for all calcination temperature. It was clearly observed that the silica xerogel exhibiting notable change in relative peak intensities showed FTIR peak splitting of υ asymmetric Si-O-Si. To uncover what happened at the FTIR peak, the deconvolution was conducted in Gaussian approach. It was established that the changes in the Gaussian peak component were related to DMDMS:TEOS molar ratios and the calcination temperature that allowed us to tailor the DMDMS:TEOS silica polymer structure model based on the peak intensity ratios. With the increase of DMDMS:TEOS molar ratio, the ratio of (cyclic Si-O-Si)/(linear Si-O-Si) decreased, whilst the ratio of (C-H)/(linear Si-O-Si) increased. Both ratios intersected at DMDMS:TEOS molar ratio of 50:50 with contribution factor ratio of 1:16 and 1:50 for silica xerogel calcined at 300°C and 500°C respectively. The importance of this research is the DMDMS:TEOS molar ratio plays an important role in determining the hydrophobic properties of thin films. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Reaction kinetics for preparation of silica film with Stoeber method

    International Nuclear Information System (INIS)

    Shang Mengying; Jiang Xiaodong; Liu Miao; Luo Xuan; Tang Yongjian; Cao Linhong

    2013-01-01

    A new formula was proposed to investigate the relationship between reaction time and tetraethylorthosilicate (TEOS) conversion rate for preparation of silica sol with Stöber method, by studying the reaction kinetics of TEOS hydrolytic process. An appropriate conversion rate was then determined and used to calculate the theoretical optimal reaction time. Meanwhile, silica sols were prepared by sol-gel process using TEOS as precursor and ammonia as catalyst. It was found that the reaction time decreases with an increasing amount of ammonia and water. The values of experimental optimal reaction time were obtained, and agree with the theoretical results (the errors are within 5%), which shows good applicability of our formula. (authors)

  17. Quality by design approach for optimizing the formulation and physical properties of extemporaneously prepared orodispersible films

    NARCIS (Netherlands)

    Visser, J. Caroline; Dohmen, Willem M. C.; Hinrichs, Wouter L. J.; Breitkreutz, Joerg; Frijlink, Henderik W.; Woerdenbag, Herman J.

    2015-01-01

    The quality by design (QbD) approach was applied for optimizing the formulation of extemporaneously prepared orodispersible films (ODFs) using Design-Expert Software. The starting formulation was based on earlier experiments and contained the film forming agents hypromellose and carbomer 974P and

  18. Flexible, cathodoluminescent and free standing mesoporous silica films with entrapped quasi-2D perovskites

    Science.gov (United States)

    Vassilakopoulou, Anastasia; Papadatos, Dionysios; Koutselas, Ioannis

    2017-04-01

    The effective entrapment of hybrid organic-inorganic semiconductors (HOIS) into mesoporous polymer-silica hybrid matrices, formed as free standing flexible films, is presented for the first time. A blend of quasi-2D HOIS, simply synthesized by mixing two-dimensional (2D) and three dimensional (3D) HOIS, exhibiting strong photoluminescence, is embedded into porous silica matrices during the sol-gel synthesis, using tetraethylorthosilicate as precursor and Pluronic F-127 triblock copolymer as structure directing agent, under acidic conditions. The final nanostructure hybrid forms flexible, free standing films, presenting high cathodoluminescence and long stable excitonic luminescence, indicating the protective character of the hybrid matrix towards the entrapped perovskite. A significant result is that the photoluminescence of the entrapped HOIS is not affected even after films' prolonged exposure to water.

  19. Positron and positronium annihilation in silica-based thin films studied by a pulsed positron beam

    International Nuclear Information System (INIS)

    Suzuki, R.; Ohdaira, T.; Kobayashi, Y.; Ito, K.; Shioya, Y.; Ishimaru, T.

    2003-01-01

    Positron and positronium annihilation in silica-based thin films has been investigated by means of measurement techniques with a monoenergetic pulsed positron beam. The age-momentum correlation study revealed that positron annihilation in thermally grown SiO 2 is basically the same as that in bulk amorphous SiO 2 while o-Ps in the PECVD grown SiCOH film predominantly annihilate with electrons of C and H at the microvoid surfaces. We also discuss time-dependent three-gamma annihilation in porous low-k films by two-dimensional positron annihilation lifetime spectroscopy

  20. Hydrophobic and optical characteristics of graphene and graphene oxide films transferred onto functionalized silica particles deposited glass surface

    Science.gov (United States)

    Yilbas, B. S.; Ibrahim, A.; Ali, H.; Khaled, M.; Laoui, T.

    2018-06-01

    Hydrophobic and optical transmittance characteristics of the functionalized silica particles on the glass surface prior and after transfer of graphene and graphene oxide films on the surface are examined. Nano-size silica particles are synthesized and functionalized via chemical grafting and deposited onto a glass surface. Graphene film, grown on copper substrate, was transferred onto the functionalized silica particles surface through direct fishing method. Graphene oxide layer was deposited onto the functionalized silica particles surface via spin coating technique. Morphological, hydrophobic, and optical characteristics of the functionalized silica particles deposited surface prior and after graphene and graphene oxide films transfer are examined using the analytical tools. It is found that the functionalized silica particles are agglomerated at the surface forming packed structures with few micro/nano size pores. This arrangement gives rise to water droplet contact angle and contact angle hysteresis in the order of 163° and 2°, respectively, and remains almost uniform over the entire surface. Transferring graphene and depositing graphene oxide films over the functionalized silica particles surface lowers the water droplet contact angle slightly (157-160°) and increases the contact angle hysteresis (4°). The addition of the graphene and graphene oxide films onto the surface of the deposited functionalized silica particles improves the optical transmittance.

  1. Silica-Coated Liposomes for Insulin Delivery

    OpenAIRE

    Neelam Dwivedi; M. A. Arunagirinathan; Somesh Sharma; Jayesh Bellare

    2010-01-01

    Liposomes coated with silica were explored as protein delivery vehicles for their enhanced stability and improved encapsulation efficiency. Insulin was encapsulated within the fluidic phosphatidylcholine lipid vesicles by thin film hydration at pH 2.5, and layer of silica was formed above lipid bilayer by acid catalysis. The presence of silica coating and encapsulated insulin was identified using confocal and electron microscopy. The native state of insulin present in the formulation was evid...

  2. Incorporation of Nanohybrid Films of Silica into Recycled Polystyrene Matrix

    Directory of Open Access Journals (Sweden)

    Genoveva Hernández-Padrón

    2015-01-01

    Full Text Available An alternative for the reutilization of polystyrene waste containers consisting in creating a hybrid material made of SiO2 nanoparticles embedded in a matrix of recycled polystyrene (PSR has been developed. Recycled polystyrene functionalized (PSRF was used to influence the morphological and antifog properties by the sol-gel synthesis of nanohybrid silica. To this end, silica nanoparticles were produced from alkoxide precursors in the presence of recycled polystyrene. The functionalization of this polymeric matrix was with the purpose of uniting in situ carboxyl and silanol groups during the sol-gel process. In this way, opaque or transparent solid substrates can be obtained, with each of these endowed with optical conditions that depend on the amount of reactants employed to prepare each nanohybrid specimen. The nanohybrids were labelled as SiO2/PSR (HPSR and SiO2/PSRF (HPSRF and their properties were then compared to those of commercial polystyrene (PS. All the prepared samples were used for coating glass substrates. The hydrophobicity of the resultant coatings was determined through contact angle measurement. The nanohybrid materials were characterized by FT-IR and 1H-NMR techniques. Additionally, TGA and SEM were employed to determine their thermal and textural properties.

  3. High-quality substrate for fluorescence enhancement using agarose-coated silica opal film.

    Science.gov (United States)

    Xu, Ming; Li, Juan; Sun, Liguo; Zhao, Yuanjin; Xie, Zhuoying; Lv, Linli; Zhao, Xiangwei; Xiao, Pengfeng; Hu, Jing; Lv, Mei; Gu, Zhongze

    2010-08-01

    To improve the sensitivity of fluorescence detection in biochip, a new kind of substrates was developed by agarose coating on silica opal film. In this study, silica opal film was fabricated on glass substrate using the vertical deposition technique. It can provide stronger fluorescence signals and thus improve the detection sensitivity. After coating with agarose, the hybrid film could provide a 3D support for immobilizing sample. Comparing with agarose-coated glass substrate, the agarose-coated opal substrates could selectively enhance particular fluorescence signals with high sensitivity when the stop band of the silica opal film in the agarose-coated opal substrate overlapped the fluorescence emission wavelength. A DNA hybridization experiment demonstrated that fluorescence intensity of special type of agarose-coated opal substrates was about four times that of agarose-coated glass substrate. These results indicate that the optimized agarose-coated opal substrate can be used for improving the sensitivity of fluorescence detection with high quality and selectivity.

  4. Preparation of mesoporous silica thin films by photocalcination method and their adsorption abilities for various proteins

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Katsuya, E-mail: katsuya-kato@aist.go.jp [National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Nakamura, Hitomi [National Institute of Advanced Industrial Science and Technology (AIST), 2266-98 Anagahora, Shimoshidami, Moriyama-ku, Nagoya 463-8560 (Japan); Yamauchi, Yoshihiro; Nakanishi, Kazuma; Tomita, Masahiro [Department of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Kurimamachiya-cho, Tsu, Mie 514-8570 (Japan)

    2014-07-01

    Mesoporous silica (MPS) thin film biosensor platforms were established. MPS thin films were prepared from tetraethoxysilane (TEOS) via using sol–gel and spin-coating methods using a poly-(ethylene oxide)-block-poly-(propylene oxide)-block-poly-(ethylene oxide) triblock polymer, such as P123 ((EO){sub 20}(PO){sub 70}(EO){sub 20}) or F127 ((EO){sub 106}(PO){sub 70}(EO){sub 106}), as the structure-directing agent. The MPS thin film prepared using P123 as the mesoporous template and treated via vacuum ultraviolet (VUV) irradiation to remove the triblock copolymer had a more uniform pore array than that of the corresponding film prepared via thermal treatment. Protein adsorption and enzyme-linked immunosorbent assay (ELISA) on the synthesized MPS thin films were also investigated. VUV-irradiated MPS thin films adsorbed a smaller quantity of protein A than the thermally treated films; however, the human immunoglobulin G (IgG) binding efficiency was higher on the former. In addition, protein A–IgG specific binding on MPS thin films was achieved without using a blocking reagent; i.e., nonspecific adsorption was inhibited by the uniform pore arrays of the films. Furthermore, VUV-irradiated MPS thin films exhibited high sensitivity for ELISA testing, and cytochrome c adsorbed on the MPS thin films exhibited high catalytic activity and recyclability. These results suggest that MPS thin films are attractive platforms for the development of novel biosensors. - Highlights: • VUV-treated MPS thin films with removed polymer had uniform pore. • VUV-treated MPS thin films exhibited high sensitivity by ELISA. • Cytochrome c showed the catalytic activity and recyclability on synthesized films.

  5. Preparation of mesoporous silica thin films by photocalcination method and their adsorption abilities for various proteins

    International Nuclear Information System (INIS)

    Kato, Katsuya; Nakamura, Hitomi; Yamauchi, Yoshihiro; Nakanishi, Kazuma; Tomita, Masahiro

    2014-01-01

    Mesoporous silica (MPS) thin film biosensor platforms were established. MPS thin films were prepared from tetraethoxysilane (TEOS) via using sol–gel and spin-coating methods using a poly-(ethylene oxide)-block-poly-(propylene oxide)-block-poly-(ethylene oxide) triblock polymer, such as P123 ((EO) 20 (PO) 70 (EO) 20 ) or F127 ((EO) 106 (PO) 70 (EO) 106 ), as the structure-directing agent. The MPS thin film prepared using P123 as the mesoporous template and treated via vacuum ultraviolet (VUV) irradiation to remove the triblock copolymer had a more uniform pore array than that of the corresponding film prepared via thermal treatment. Protein adsorption and enzyme-linked immunosorbent assay (ELISA) on the synthesized MPS thin films were also investigated. VUV-irradiated MPS thin films adsorbed a smaller quantity of protein A than the thermally treated films; however, the human immunoglobulin G (IgG) binding efficiency was higher on the former. In addition, protein A–IgG specific binding on MPS thin films was achieved without using a blocking reagent; i.e., nonspecific adsorption was inhibited by the uniform pore arrays of the films. Furthermore, VUV-irradiated MPS thin films exhibited high sensitivity for ELISA testing, and cytochrome c adsorbed on the MPS thin films exhibited high catalytic activity and recyclability. These results suggest that MPS thin films are attractive platforms for the development of novel biosensors. - Highlights: • VUV-treated MPS thin films with removed polymer had uniform pore. • VUV-treated MPS thin films exhibited high sensitivity by ELISA. • Cytochrome c showed the catalytic activity and recyclability on synthesized films

  6. A Robust Fiber Bragg Grating Hydrogen Gas Sensor Using Platinum-Supported Silica Catalyst Film

    Directory of Open Access Journals (Sweden)

    Marina Kurohiji

    2018-01-01

    Full Text Available A robust fiber Bragg grating (FBG hydrogen gas sensor for reliable multipoint-leakage monitoring has been developed. The sensing mechanism is based on shifts of center wavelength of the reflection spectra due to temperature change caused by catalytic combustion heat. The sensitive film which consists of platinum-supported silica (Pt/SiO2 catalyst film was obtained using sol-gel method. The precursor solution was composed of hexachloroplatinic acid and commercially available silica precursor solution. The atom ratio of Si : Pt was fixed at 13 : 1. A small amount of this solution was dropped on the substrate and dried at room temperature. After that, the film was calcined at 500°C in air. These procedures were repeated and therefore thick hydrogen-sensitive films were obtained. The catalytic film obtained by 20-time coating on quartz glass substrate showed a temperature change 75 K upon exposure to 3 vol.% H2. For realizing robust sensor device, this catalytic film was deposited and FBG portion was directly fixed on titanium substrate. The sensor device showed good performances enough to detect hydrogen gas in the concentration range below lower explosion limit at room temperature. The enhancement of the sensitivity was attributed to not only catalytic combustion heat but also related thermal strain.

  7. Thickness controlled sol-gel silica films for plasmonic bio-sensing devices

    Energy Technology Data Exchange (ETDEWEB)

    Figus, Cristiana, E-mail: cristiana.figus@dsf.unica.it; Quochi, Francesco, E-mail: cristiana.figus@dsf.unica.it; Artizzu, Flavia, E-mail: cristiana.figus@dsf.unica.it; Saba, Michele, E-mail: cristiana.figus@dsf.unica.it; Marongiu, Daniela, E-mail: cristiana.figus@dsf.unica.it; Mura, Andrea; Bongiovanni, Giovanni [Dipartimento di Fisica - University of Cagliari, S.P. Km 0.7, I-09042 Monserrato (Canada) (Italy); Floris, Francesco; Marabelli, Franco; Patrini, Maddalena; Fornasari, Lucia [Dipartimento di Fisica - University of Pavia, Via Agostino Bassi 6, I-27100 Pavia (PV) (Italy); Pellacani, Paola; Valsesia, Andrea [Plasmore S.r.l. -Via Grazia Deledda 4, I-21020 Ranco (Vatican City State, Holy See) (Italy)

    2014-10-21

    Plasmonics has recently received considerable interest due to its potentiality in many fields as well as in nanobio-technology applications. In this regard, various strategies are required for modifying the surfaces of plasmonic nanostructures and to control their optical properties in view of interesting application such as bio-sensing, We report a simple method for depositing silica layers of controlled thickness on planar plasmonic structures. Tetraethoxysilane (TEOS) was used as silica precursor. The control of the silica layer thickness was obtained by optimizing the sol-gel method and dip-coating technique, in particular by properly tuning different parameters such as pH, solvent concentration, and withdrawal speed. The resulting films were characterized via atomic force microscopy (AFM), Fourier-transform (FT) spectroscopy, and spectroscopic ellipsometry (SE). Furthermore, by performing the analysis of surface plasmon resonances before and after the coating of the nanostructures, it was observed that the position of the resonance structures could be properly shifted by finely controlling the silica layer thickness. The effect of silica coating was assessed also in view of sensing applications, due to important advantages, such as surface protection of the plasmonic structure.

  8. Pore Structure Control of Ordered Mesoporous Silica Film Using Mixed Surfactants

    Directory of Open Access Journals (Sweden)

    Tae-Jung Ha

    2011-01-01

    Full Text Available Materials with nanosized and well-arranged pores have been researched actively in order to be applied to new technology fields. Especially, mesoporous material containing various pore structures is expected to have different pore structure. To form a mixed pore structure, ordered mesoporous silica films were prepared with a mixture of surfactant; Brij-76 and P-123 block copolymer. In mixed surfactant system, mixed pore structure was observed in the region of P-123/(Brij-76 + P-123 with about 50.0 wt.% while a single pore structure was observed in regions which have large difference in ratio between Brij-76 and P-123 through the X-ray diffraction analysis. Regardless of surfactant ratio, porosity was retained almost the same. It is expected that ordered mesoporous silica film with mixed pore structure can be one of the new materials which has distinctive properties.

  9. Evaluation of optical properties of the amorphous carbon film on fused silica

    International Nuclear Information System (INIS)

    Baydogan, Nilguen Dogan

    2004-01-01

    Deposition was done using a pulsed filtered cathodic arc with a graphite cathode. The carbon plasma is fully ionised and condenses on the substrate, forming diamond-like material but with amorphous structure. Optical properties of amorphous carbon films on fused-silica glass were investigated and the curves of optical density have a characteristic band at approximately 950 nm. Changes of the colourimetric quantities were evaluated and compared to uncoated fused silica glass. These changes were investigated as a function of the applied substrate bias voltage using the CIE and CIELAB colour systems. It is suggested that the mechanism of absorption is related to an allowed direct transition at the amorphous carbon films on fused silica glass. The optical energy gap of the amorphous carbon film depends on the bias voltage applied to the substrate holder. The optical colour parameters and optical band gap indicated that there is a relation between the dominant wavelength of the reflectance in the visible range and the wavelength of the optical band gap

  10. Structure and properties of low-n mesoporous silica films for optical applications

    International Nuclear Information System (INIS)

    Konjhodzic, Denan; Bretinger, Helmut; Marlow, Frank

    2006-01-01

    The properties and structure of the mesoporous silica films synthesized by dip-coating in evaporation-induced self-assembly are investigated. The nonionic triblock copolymer EO 2 PO 7 EO 2 has been used as a template in this modified sol-gel process. A strong dependence of the formed structure on the processing conditions, especially humidity, has been revealed allowing an appreciable structure tuning. Low humidity allows the reproducible synthesis of low refractive index films, which were used as optical waveguide supports. They are crack-free, transparent, thermally stable, very smooth, and have a thickness up to 1 μm. Under higher humidity conditions a novel sustained lamellar structure was synthesized, that remains stable upon calcination. The films were characterized by angle-dependent interferometry, small angle X-ray scattering (SAXS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). 2D photonic crystals made of different materials, such as polymers can be deposited onto these films

  11. Spray-drying nanocapsules in presence of colloidal silica as drying auxiliary agent: formulation and process variables optimization using experimental designs.

    Science.gov (United States)

    Tewa-Tagne, Patrice; Degobert, Ghania; Briançon, Stéphanie; Bordes, Claire; Gauvrit, Jean-Yves; Lanteri, Pierre; Fessi, Hatem

    2007-04-01

    Spray-drying process was used for the development of dried polymeric nanocapsules. The purpose of this research was to investigate the effects of formulation and process variables on the resulting powder characteristics in order to optimize them. Experimental designs were used in order to estimate the influence of formulation parameters (nanocapsules and silica concentrations) and process variables (inlet temperature, spray-flow air, feed flow rate and drying air flow rate) on spray-dried nanocapsules when using silica as drying auxiliary agent. The interactions among the formulation parameters and process variables were also studied. Responses analyzed for computing these effects and interactions were outlet temperature, moisture content, operation yield, particles size, and particulate density. Additional qualitative responses (particles morphology, powder behavior) were also considered. Nanocapsules and silica concentrations were the main factors influencing the yield, particulate density and particle size. In addition, they were concerned for the only significant interactions occurring among two different variables. None of the studied variables had major effect on the moisture content while the interaction between nanocapsules and silica in the feed was of first interest and determinant for both the qualitative and quantitative responses. The particles morphology depended on the feed formulation but was unaffected by the process conditions. This study demonstrated that drying nanocapsules using silica as auxiliary agent by spray drying process enables the obtaining of dried micronic particle size. The optimization of the process and the formulation variables resulted in a considerable improvement of product yield while minimizing the moisture content.

  12. Characterization of fluorinated silica thin films with ultra-low refractive index deposited at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi-Firouzjah, Marzieh [Semnan Science and Technology Park, 3614933578, Shahrood (Iran, Islamic Republic of); Shokri, Babak, E-mail: b-shokri@sbu.ac.ir [Laser & Plasma Research Institute, Shahid Beheshti University, G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of); Physics Department, Shahid Beheshti University, G.C., Evin, Tehran 1983963113 (Iran, Islamic Republic of)

    2015-02-27

    Structural and optical properties of low refractive index fluorinated silica (SiO{sub x}C{sub y}F{sub z}) films were investigated. The films were deposited on p-type silicon and polycarbonate substrates by radio frequency plasma enhanced chemical vapor deposition method at low temperatures. A mixture of tetraethoxysilane vapor, oxygen, and CF{sub 4} was used for deposition of the films. The influence of oxygen flow rate on the elemental compositions, chemical bonding states and surface roughness of the films was studied using energy dispersive X-ray analyzer, Fourier transform infrared spectroscopy in reflectance mode and atomic force microscopy, respectively. Effects of chemical bonds of the film matrix on optical properties and chemical stability were discussed. Energy dispersive spectroscopy showed high fluorine content in the SiO{sub x}C{sub y}F{sub z} film matrix which is in the range of 7.6–11.3%. It was concluded that in fluorine content lower than a certain limit, chemical stability of the film enhances, while higher contents of fluorine heighten moisture absorption followed by increasing refractive index. All of the deposited films were highly transparent. Finally, it was found that the refractive index of the SiO{sub x}C{sub y}F{sub z} film was continuously decreased with the increase of the O{sub 2} flow rate down to the minimum value of 1.16 ± 0.01 (at 632.8 nm) having the most ordered and nano-void structure and the least organic impurities. This sample also had the most chemical stability against moisture absorption. - Highlights: • Low deposition temperature and organic precursor led to higher film fluorination. • High fluorine and nanovoid structure led to drastic decrease in the refractive index. • Silica based thin film with ultralow refractive index of 1.16 was produced. • The produced ultralow-n film is highly stable against moisture absorption.

  13. A Thin Film Nanocomposite Membrane with MCM-41 Silica Nanoparticles for Brackish Water Purification

    Directory of Open Access Journals (Sweden)

    Mohammed Kadhom

    2016-12-01

    Full Text Available Thin film nanocomposite (TFN membranes containing MCM-41 silica nanoparticles (NPs were synthesized by the interfacial polymerization (IP process. An m-phenylenediamine (MPD aqueous solution and an organic phase with trimesoyl chloride (TMC dissolved in isooctane were used in the IP reaction, occurring on a nanoporous polysulfone (PSU support layer. Isooctane was introduced as the organic solvent for TMC in this work due to its intermediate boiling point. MCM-41 silica NPs were loaded in MPD and TMC solutions in separate experiments, in a concentration range from 0 to 0.04 wt %, and the membrane performance was assessed and compared based on salt rejection and water flux. The prepared membranes were characterized via scanning electron microscopy (SEM, transmission electron microscopy (TEM, contact angle measurement, and attenuated total reflection Fourier transform infrared (ATR FT-IR analysis. The results show that adding MCM-41 silica NPs into an MPD solution yields slightly improved and more stable results than adding them to a TMC solution. With 0.02% MCM-41 silica NPs in the MPD solution, the water flux was increased from 44.0 to 64.1 L/m2·h, while the rejection virtually remained the same at 95% (2000 ppm NaCl saline solution, 25 °C, 2068 kPa (300 psi.

  14. A Thin Film Nanocomposite Membrane with MCM-41 Silica Nanoparticles for Brackish Water Purification.

    Science.gov (United States)

    Kadhom, Mohammed; Yin, Jun; Deng, Baolin

    2016-12-06

    Thin film nanocomposite (TFN) membranes containing MCM-41 silica nanoparticles (NPs) were synthesized by the interfacial polymerization (IP) process. An m -phenylenediamine (MPD) aqueous solution and an organic phase with trimesoyl chloride (TMC) dissolved in isooctane were used in the IP reaction, occurring on a nanoporous polysulfone (PSU) support layer. Isooctane was introduced as the organic solvent for TMC in this work due to its intermediate boiling point. MCM-41 silica NPs were loaded in MPD and TMC solutions in separate experiments, in a concentration range from 0 to 0.04 wt %, and the membrane performance was assessed and compared based on salt rejection and water flux. The prepared membranes were characterized via scanning electron microscopy (SEM), transmission electron microscopy (TEM), contact angle measurement, and attenuated total reflection Fourier transform infrared (ATR FT-IR) analysis. The results show that adding MCM-41 silica NPs into an MPD solution yields slightly improved and more stable results than adding them to a TMC solution. With 0.02% MCM-41 silica NPs in the MPD solution, the water flux was increased from 44.0 to 64.1 L/m²·h, while the rejection virtually remained the same at 95% (2000 ppm NaCl saline solution, 25 °C, 2068 kPa (300 psi)).

  15. Formulation of chitosan-based ciprofloxacin and diclofenac film for ...

    African Journals Online (AJOL)

    Purpose: This study was designed to develop and evaluate chitosan films containing ciprofloxacin and diclofenac sodium for the topical treatment of periodontitis. Methods: Chitosan films containing ciprofloxacin alone and in combination with diclofenac sodium were prepared by solvent casting method. Some of the ...

  16. Development of pore interconnectivity/morphology in porous silica films investigated by cyclic voltammetry and slow positron annihilation spectroscopy

    International Nuclear Information System (INIS)

    Tang, Xiuqin; Xiong, Bangyun; Li, Qichao; Mao, Wenfeng; Xiao, Wei; Fang, Pengfei; He, Chunqing

    2015-01-01

    Highlights: •Porous silica films were studied by cyclic voltammetry and positron annihilation. •Highly interconnected pores were formed in the film fabricated with more CTAB. •Aligned nanochannels were observed in the porous flim prepared with 25 wt.% CTAB. •I − and Ps diffusion in the films was governed by pore interconnectivity/morphology. •Cyclic voltammetry is feasible to explore pore interconnectivity/morphology. -- Abstract: Cyclic voltammetry and positronium (Ps) 3γ-annihilation spectroscopy were applied to investigate pore interconnectivity/morphology of porous silica films fabricated with various loading of cetyltrimethyl ammonium bromide (CTAB). With increasing the ratio of CTAB up to 15 wt.%, the total charge Q, resulted from I − diffusion across the silica films, increased remarkably, indicative of formation of highly interconnected pores in the films prepared with more porogen. However, it decreased dramatically with further loading CTAB of 25 wt.%. Interestingly, 3γ-annihilation fraction I 3γ due to a triplet-state Ps (ortho-positronium, o-Ps) emission from the silica films showed a similar behavior as a function of CTAB loading. The abnormal decrement in Q and I 3γ in the film fabricated with 25 wt.% CTAB was well explained by formation of long nanochannels aligning parallel to the film surface. The results indicated that the total charge Q and Ps 3γ-annihilation fraction were closely associated with I − and Ps diffusion governed by the pore interconnectivity/morphology of the silica films, which made cyclic voltammetry possible to be a feasible tool to characterize pore interconnectivity/morphology of porous thin films

  17. Reinforcement of LENRA film by in-situ generated silica produced by sol gel process

    International Nuclear Information System (INIS)

    Mahathir Mohamed; Eda Yuhana Ariffin; Dahlan Mohd; Ibrahim Abdullah

    2008-08-01

    Liquid epoxidised natural rubber acrylate (LENRA) film was reinforced with silica-siloxane structures formed in-situ via sol gel process. Combination of these two components produces organic-inorganic composites. Tetraethylorthosilicate (TEOS) was used as precursor material for silica generation. Sol gel reaction was carried out at different concentrations of TEOS i.e. between 10 and 50 phr. Instrumental analysis was carried out by dynamic mechanical analysis (DMA), thermogravimetry analysis (TGA) and FTIR. It was found that miscibility between organic and inorganic components improved with the presence of silanol groups (Si-OH) and polar solvent i.e. THF, via hydrogen bonding formation between siloxane and LENRA. In this work, the effects of TEOS composition on mechanical properties and interaction that occurs between fillers and matrix have also been studied. It was observed that increasing the concentration of TEOS improved the scratch and stress properties of the film. Morphology study by the scanning electron microscopy (SEM) showed in-situ generated silica particles were homogenous and well dispersed at low concentrations of TEOS. (Author)

  18. Steady state and time resolved fluorescence studies of azadioxatriangulenium (ADOTA) fluorophore in silica and PVA thin films

    DEFF Research Database (Denmark)

    Chib, Rahul; Raut, Sangram; Shah, Sunil

    2015-01-01

    A cationic azadioxatriangulenium dye was entrapped in silica thin films obtained by the sol-gel process and in poly (vinyl) alcohol (PVA) thin films. Azadioxatriangulenium is a red emitting fluorophore with a long fluorescence lifetime of ∼20 ns. The fluorescent properties of azadioxatriangulenium...

  19. Quantum dots/silica/polymer nanocomposite films with high visible light transmission and UV shielding properties.

    Science.gov (United States)

    Mumin, Md Abdul; Xu, William Z; Charpentier, Paul A

    2015-08-07

    The dispersion of light-absorbing inorganic nanomaterials in transparent plastics such as poly(ethylene-co-vinyl acetate) (PEVA) is of enormous current interest in emerging solar materials, including photovoltaic (PV) modules and commercial greenhouse films. Nanocrystalline semiconductor or quantum dots (QDs) have the potential to absorb UV light and selectively emit visible light, which can control plant growth in greenhouses or enhance PV panel efficiencies. This work provides a new and simple approach for loading mesoporous silica-encapsulated QDs into PEVA. Highly luminescent CdS and CdS-ZnS core-shell QDs with 5 nm size were synthesized using a modified facile approach based on pyrolysis of the single-molecule precursors and capping the CdS QDs with a thin layer of ZnS. To make both the bare and core-shell structure QDs more resistant against photochemical reactions, a mesoporous silica layer was grown on the QDs through a reverse microemulsion technique based on hydrophobic interactions. By careful experimental tuning, this encapsulation technique enhanced the quantum yield (∼65%) and photostability compared to the bare QDs. Both the encapsulated bare and core-shell QDs were then melt-mixed with EVA pellets using a mini twin-screw extruder and pressed into thin films with controlled thickness. The results demonstrated for the first time that mesoporous silica not only enhanced the quantum yield and photostability of the QDs but also improved the compatibility and dispersibility of QDs throughout the PEVA films. The novel light selective films show high visible light transmission (∼90%) and decreased UV transmission (∼75%).

  20. Superhydrophobic transparent films from silica powder: Comparison of fabrication methods

    KAUST Repository

    Liu, Li-Der; Lin, Chao-Sung; Tikekar, Mukul; Chen, Ping-Hei

    2011-01-01

    The lotus leaf is known for its self-clean, superhydrophobic surface, which displays a hierarchical structure covered with a thin wax-like material. In this study, three fabrication techniques, using silicon dioxide particles to create surface roughness followed by a surface modification with a film of polydimethylsiloxane, were applied on a transparent glass substrate. The fabrication techniques differed mainly on the deposition of silicon dioxide particles, which included organic, inorganic, and physical methods. Each technique was used to coat three samples of varying particle load. The surface of each sample was evaluated with contact angle goniometer and optical spectrometer. Results confirmed the inverse relationships between contact angle and optical transmissivity independent of fabrication techniques. Microstructural morphologies also suggested the advantage of physical deposition over chemical methods. In summary, the direct sintering method proved outstanding for its contact angle vs transmissivity efficiency, and capable of generating a contact angle as high as 174°. © 2011 Elsevier B.V. All rights reserved.

  1. Superhydrophobic transparent films from silica powder: Comparison of fabrication methods

    KAUST Repository

    Liu, Li-Der

    2011-07-01

    The lotus leaf is known for its self-clean, superhydrophobic surface, which displays a hierarchical structure covered with a thin wax-like material. In this study, three fabrication techniques, using silicon dioxide particles to create surface roughness followed by a surface modification with a film of polydimethylsiloxane, were applied on a transparent glass substrate. The fabrication techniques differed mainly on the deposition of silicon dioxide particles, which included organic, inorganic, and physical methods. Each technique was used to coat three samples of varying particle load. The surface of each sample was evaluated with contact angle goniometer and optical spectrometer. Results confirmed the inverse relationships between contact angle and optical transmissivity independent of fabrication techniques. Microstructural morphologies also suggested the advantage of physical deposition over chemical methods. In summary, the direct sintering method proved outstanding for its contact angle vs transmissivity efficiency, and capable of generating a contact angle as high as 174°. © 2011 Elsevier B.V. All rights reserved.

  2. Dataset for acrylate/silica nanoparticles formulations and photocured composites: Viscosity, filler dispersion and bulk Poisson׳s ratio

    Directory of Open Access Journals (Sweden)

    Hubert Gojzewski

    2017-06-01

    Full Text Available UV-curable polymer composites are of importance in industry, biomedical applications, scientific fields, and daily life. Outstanding physical properties of polymer composites were achieved with nanoparticles as filler, primarily in enhancing mechanical strength or barrier properties. Structure-property relationships of the resulting nanocomposites are dictated by the polymer-filler molecular architecture, i.e. interactions between polymer matrix and filler, and high surface area to volume ratio of the filler particles. Among monomers, acrylates and methacrylates attracted wide attention due to their ease of polymerization and excellent physicochemical and mechanical properties of the derived polymers. We prepared and photopolymerized two series of formulations containing hydrophobized silica nanofiller (Aerosil R7200 dispersed in 2-hydroxyethyl acrylate (HEA or polyethylene glycol diacrylate (PEGDA monomers. We compared selected physical properties of the formulations, both before and after photocuring; specifically the viscosity of formulations and dispersion of the filler in the polymer matrices. Additionally, we estimated the bulk Poisson׳s ratio of the investigated nanocomposites. This article contains data related to the research article entitled “Nanoscale Young׳s modulus and surface morphology in photocurable polyacrylate/nanosilica composites” (Gojzewski et al., 2017 [1].

  3. Silica doped with lanthanum sol–gel thin films for corrosion protection

    International Nuclear Information System (INIS)

    Abuín, M.; Serrano, A.; Llopis, J.; García, M.A.; Carmona, N.

    2012-01-01

    We present here anticorrosive silica coatings doped with lanthanum ions for the protection of metallic surfaces as an alternative to chromate (VI)-based conversion coatings. The coatings were synthesized by the sol–gel method starting from silicon alkoxides and two different lanthanum precursors: La (III) acetate hydrate and La (III) isopropoxide. Artificial corrosion tests in acid and alkaline media showed their effectiveness for the corrosion protection of AA2024 aluminum alloy sheets for coating prepared with both precursors. The X-ray absorption Near Edge Structure and X-ray Absorption Fine Structure analysis of the coatings confirmed the key role of lanthanum in the structural properties of the coating determining its anticorrosive properties. - Highlights: ► Silica sol–gel films doped with lanthanum ions were synthesized. ► Films from lanthanum-acetate and La-alkoxide were prepared for comparison purposes. ► La-acetate is an affordable chemical reactive preferred for the industry. ► Films properties were explored by scanning electron microscopy and X-Ray absorption spectroscopy. ► An alternative to anticorrosive pre-treatments for metallic surfaces is suggested.

  4. Silica doped with lanthanum sol-gel thin films for corrosion protection

    Energy Technology Data Exchange (ETDEWEB)

    Abuin, M. [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain); Serrano, A. [Glass and Ceramic Institute, CSIC, C. Kelsen 5, 28049 Madrid (Spain); Llopis, J. [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain); Garcia, M.A. [Glass and Ceramic Institute, CSIC, C. Kelsen 5, 28049 Madrid (Spain); IMDEA Nanoscience, Fco. Tomas y Valiente 7, 28049 Madrid (Spain); Carmona, N., E-mail: n.carmona@fis.ucm.es [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain)

    2012-06-01

    We present here anticorrosive silica coatings doped with lanthanum ions for the protection of metallic surfaces as an alternative to chromate (VI)-based conversion coatings. The coatings were synthesized by the sol-gel method starting from silicon alkoxides and two different lanthanum precursors: La (III) acetate hydrate and La (III) isopropoxide. Artificial corrosion tests in acid and alkaline media showed their effectiveness for the corrosion protection of AA2024 aluminum alloy sheets for coating prepared with both precursors. The X-ray absorption Near Edge Structure and X-ray Absorption Fine Structure analysis of the coatings confirmed the key role of lanthanum in the structural properties of the coating determining its anticorrosive properties. - Highlights: Black-Right-Pointing-Pointer Silica sol-gel films doped with lanthanum ions were synthesized. Black-Right-Pointing-Pointer Films from lanthanum-acetate and La-alkoxide were prepared for comparison purposes. Black-Right-Pointing-Pointer La-acetate is an affordable chemical reactive preferred for the industry. Black-Right-Pointing-Pointer Films properties were explored by scanning electron microscopy and X-Ray absorption spectroscopy. Black-Right-Pointing-Pointer An alternative to anticorrosive pre-treatments for metallic surfaces is suggested.

  5. Optical and electrical properties of boron doped diamond thin conductive films deposited on fused silica glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Ficek, M.; Sobaszek, M.; Gnyba, M. [Department of Metrology and Optoelectronics, Gdansk University of Technology, 11/12G. Narutowicza St., 80-233 Gdansk (Poland); Ryl, J. [Department of Electrochemistry, Corrosion and Material Engineering, Gdansk University of Technology, 11/12 Narutowicza St., 80-233 Gdansk (Poland); Gołuński, Ł. [Department of Metrology and Optoelectronics, Gdansk University of Technology, 11/12G. Narutowicza St., 80-233 Gdansk (Poland); Smietana, M.; Jasiński, J. [Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, 75 Koszykowa St., 00-662 Warsaw (Poland); Caban, P. [Institute of Electronic Materials Technology, 133 Wolczynska St., 01-919 Warsaw (Poland); Bogdanowicz, R., E-mail: rbogdan@eti.pg.gda.pl [Department of Metrology and Optoelectronics, Gdansk University of Technology, 11/12G. Narutowicza St., 80-233 Gdansk (Poland); Materials and Process Simulation Center, California Institute of Technology, Pasadena, CA 91125 (United States)

    2016-11-30

    Highlights: • Growth of 60% of transmittance diamond films with resistivity as low as 48 Ω cm. • Two step seeding process of fused silica: plasma hydrogenation and wet seeding. • Nanodiamond seeding density of 2 × 10{sup 10} cm{sup −2} at fused silica substrates. • High refractive index (2.4 @550 nm) was achieved for BDD films deposited at 500 °C. - Abstract: This paper presents boron-doped diamond (BDD) film as a conductive coating for optical and electronic purposes. Seeding and growth processes of thin diamond films on fused silica have been investigated. Growth processes of thin diamond films on fused silica were investigated at various boron doping level and methane admixture. Two step pre-treatment procedure of fused silica substrate was applied to achieve high seeding density. First, the substrates undergo the hydrogen plasma treatment then spin-coating seeding using a dispersion consisting of detonation nanodiamond in dimethyl sulfoxide with polyvinyl alcohol was applied. Such an approach results in seeding density of 2 × 10{sup 10} cm{sup −2}. The scanning electron microscopy images showed homogenous, continuous and polycrystalline surface morphology with minimal grain size of 200 nm for highly boron doped films. The sp{sup 3}/sp{sup 2} ratio was calculated using Raman spectra deconvolution method. A high refractive index (range of 2.0–2.4 @550 nm) was achieved for BDD films deposited at 500 °C. The values of extinction coefficient were below 0.1 at λ = 550 nm, indicating low absorption of the film. The fabricated BDD thin films displayed resistivity below 48 Ohm cm and transmittance over 60% in the visible wavelength range.

  6. Preparation of silane-functionalized silica films via two-step dip coating sol–gel and evaluation of their superhydrophobic properties

    International Nuclear Information System (INIS)

    Ramezani, Maedeh; Vaezi, Mohammad Reza; Kazemzadeh, Asghar

    2014-01-01

    Highlights: • Superhydrophobic silica film was prepared by sol–gel process. • The surfaces exhibited superhydrophobicity with water contact angle greater than 150°. • AFM images showed the roughness increases with increasing the percentage of silylation agent. • Before and after modification, the particle size of silica was lower than 50 nm. - Graphical abstract: Schematic illustration of the surface modification of the silica nanoparticle by iso-OTMS on the glass substrate. - Abstract: In this paper, we study the two-step dip coating via a sol–gel process to prepare superhydrophobic silica films on the glass substrate. The water repellency of the silica films was controlled by surface silylation method using isooctyltrimethoxysilane (iso-OTMS) as a surface modifying agent. Silica alcosol was synthesized by keeping the molar ratio of ethyltriethoxysilane (ETES) precursor, ethanol (EtOH) solvent, water (H 2 O) was kept constant at 1:36:6.6 respectively, with 6 M NH 4 OH throughout the experiment and the percentages of hydrophobic agent in hexane bath was varied from 0 to 15 vol.%. The static water contact angle values of the silica films increased from 108° to 160° with an increase in the vol.% of iso-OTMS. At 15 vol%. of iso-OTMS, the silica film shows static water contact angle as high as 160°. The superhydrophobic silica films are thermally stable up to 440 °C and above this temperature, the silica films lose superhydrophobicity. By controlling the primer particle size of SiO 2 about 26 nm, leading to decrease the final size of silica nanoparticles after modification of nanoparticles by isooctyltrimethoxysilane about 42 nm. The films are transparent and have uniform size on the surface. The silica films have been characterized by atomic force microscopy (AFM), fourier transform infrared spectroscopy (FT-IR), transparency, contact angle measurement (CA), Zeta-potential, Thermal stability by TG–DTA analysis

  7. Solution-processable precursor route for fabricating ultrathin silica film for high performance and low voltage organic transistors

    Institute of Scientific and Technical Information of China (English)

    Shujing Guo; Liqiang Li; Zhongwu Wang; Zeyang Xu; Shuguang Wang; Kunjie Wu; Shufeng Chen; Zongbo Zhang; Caihong Xu; Wenfeng Qiu

    2017-01-01

    Silica is one of the most commonly used materials for dielectric layer in organic thin-film transistors due to its excellent stability,excellent electrical properties,mature preparation process,and good compatibility with organic semiconductors.However,most of conventional preparation methods for silica film are generally performed at high temperature and/or high vacuum.In this paper,we introduce a simple solution spin-coating method to fabricate silica thin film from precursor route,which possesses a low leakage current,high capacitance,and low surface roughness.The silica thin film can be produced in the condition of low temperature and atmospheric environment.To meet various demands,the thickness of film can be adjusted by means of preparation conditions such as the speed of spin-coating and the concentration of solution.The p-type and n-type organic field effect transistors fabricated by using this film as gate electrodes exhibit excellent electrical performance including low voltage and high performance.This method shows great potential for industrialization owing to its characteristic of low consumption and energy saving,time-saving and easy to operate.

  8. Organized mesoporous silica films as templates for the elaboration of organized nanoparticle networks

    International Nuclear Information System (INIS)

    Gacoin, T; Besson, S; Boilot, J P

    2006-01-01

    Tremendous work achieved in the last 20 years on nanoparticle synthesis has allowed us to study many new physical properties that are found in the nanometre size range. New developments are now expected when considering assemblies of nanoparticles such as 2D or 3D organized arrays. These systems are indeed expected to exhibit original physical properties resulting from particle-particle interactions. Studies in this field are clearly dependent on the elaboration of materials with controlled particle size, organization and interparticle distance. This paper presents a strategy of elaboration that is based on the use of organized mesoporous silica films as templates. These films are made by sol-gel polymerization around surfactant assemblies and further elimination of the surfactant. This provides porous matrices with a pore organization that is the almost perfect replica of the initial micellar structure. The use of such films for the elaboration of organized arrays of nanoparticles is detailed in the case of CdS and Ag particles. The formation of particles inside the pores is achieved through impregnation with precursors that are allowed to diffuse inside the pores. This leads to particles with a size and a spatial arrangement that is directly related to the initial pore structure of the films. This process opens a wide range of investigations due to the relative ease of fabrication over large surfaces and the numerous possibilities offered by the elaboration of porous films with different pore sizes and organizations

  9. Luminescent hybrid films obtained by covalent grafting of terbium complex to silica network

    International Nuclear Information System (INIS)

    Liu Fengyi; Fu Lianshe; Wang Jun; Liu Ze; Li Huanrong; Zhang Hongjie

    2002-01-01

    Luminescent hybrid thin films consisting of terbium complex covalently bonded to a silica-based network have been obtained in situ via a sol-gel approach. A new monomer, N-(4-benzoic acid-yl), N'-(propyltriethoxysilyl)urea (PABI), has been synthesized by grafting isocyanatopropyltriethoxysilane (ICPTES) to p-aminobenzoic acid and characterized by 1 H NMR, IR and MS. The monomer acts as a ligand for Tb 3+ ion and as a sol-gel precursor. Band emission from Tb 3+ ion due to an efficient ligand-to-metal energy transfer was observed by UV excitation. The decay curves of Tb 3+ in the hybrid films were measured. The energy difference between the triplet state energy of PABI and the 5 D 4 level of Tb 3+ ion falls in the exciting range to sensitize Tb 3+ ion fluorescence

  10. High drug load, stable, manufacturable and bioavailable fenofibrate formulations in mesoporous silica: a comparison of spray drying versus solvent impregnation methods.

    Science.gov (United States)

    Hong, Shiqi; Shen, Shoucang; Tan, David Cheng Thiam; Ng, Wai Kiong; Liu, Xueming; Chia, Leonard S O; Irwan, Anastasia W; Tan, Reginald; Nowak, Steven A; Marsh, Kennan; Gokhale, Rajeev

    2016-01-01

    Encapsulation of drugs in mesoporous silica using co-spray drying process has been recently explored as potential industrial method. However, the impact of spray drying on manufacturability, physiochemical stability and bioavailability in relation to conventional drug load processes are yet to be fully investigated. Using a 2(3) factorial design, this study aims to investigate the effect of drug-loading process (co-spray drying and solvent impregnation), mesoporous silica pore size (SBA-15, 6.5 nm and MCM-41, 2.5 nm) and percentage drug load (30% w/w and 50% w/w) on material properties, crystallinity, physicochemical stability, release profiles and bioavailability of fenofibrate (FEN) loaded into mesoporous silica. From the scanning electronic microscopy (SEM) images, powder X-ray diffraction and Differential scanning calorimetry measurements, it is indicated that the co-spray drying process was able to load up to 50% (w/w) FEN in amorphous form onto the mesoporous silica as compared to the 30% (w/w) for solvent impregnation. The in vitro dissolution rate of the co-spray dried formulations was also significantly (p = 0.044) better than solvent impregnated formulations at the same drug loading. Six-month accelerated stability test at 40 °C/75 RH in open dish indicated excellent physical and chemical stability of formulations prepared by both methods. The amorphous state of FEN and the enhanced dissolution profiles were well preserved, and very low levels of degradation were detected after storage. The dog data for the three selected co-spray-dried formulations revealed multiple fold increment in FEN bioavailability compared to the reference crystalline FEN. These results validate the viability of co-spray-dried mesoporous silica formulations with high amorphous drug load as potential drug delivery systems for poorly water soluble drugs.

  11. Stability of erbium and silver implanted in silica-titania sol-gel films

    International Nuclear Information System (INIS)

    Ramos, A.R.; Marques, C.; Alves, E.; Marques, A.C.; Almeida, R.M.

    2005-01-01

    We implanted silica-titania sol-gel films with 3 x 10 15 at./cm 2 , 180 keV Er + and 6 x 10 16 at./cm 2 , 140 keV Ag + ions. The energies were chosen so that the profiles of Ag and Er overlap. RBS and ERDA were used to study the behaviour of Ag, Er and H during the heat treatments used to density the films. Implantation causes H depletion at the film surface and an increase in H concentration just beneath the implanted Ag and Er profiles. The total H content decreases by 27% to 75% during implantation. During annealing the H content decreases, with an almost complete H loss after annealing for 35 min at 800 deg. C. The Ag profile remains stable up to 600 deg. C. Above 700 deg. C Ag becomes increasingly mobile. Annealing at 800 deg. C for 35 min results in a nearly constant Ag distribution in the film. The Er profile remains unchanged with heat treatment up to the maximum temperature used (800 deg. C)

  12. Polymer-Silica nanoparticles composite films as protective coatings for stone-based monuments

    Energy Technology Data Exchange (ETDEWEB)

    Manoudis, P [Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki (Greece); Papadopoulou, S [Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki (Greece); Karapanagiotis, I [' Ormylia' Art Diagnosis Centre, Ormylia, Chalkidiki, 63071 (Greece); Tsakalof, A [Medical Department, University of Thessaly, Larissa, 41222 (Greece); Zuburtikudis, I [Department of Industrial Design Engineering, TEI of Western Macedonia, Kozani, 50100 (Greece); Panayiotou, C [Department of Chemical Engineering, Aristotle University of Thessaloniki, 54124, Thessaloniki (Greece)

    2007-04-15

    The decrease of surface energy of mineral substrates similar to those used in many stone monuments of cultural heritage by the application of protective polymer coatings along with the simultaneous increase of their surface roughness can increase their ability to repel water substantially. In this work, the effect of artificially induced roughness on the water repellency of mineral substrates coated with protective polymer films was investigated. Natural marble samples or home made calcium carbonate blocks were tried as the mineral substrates. The roughness increase was achieved by mineral chemical etching or by creation of nanoscale binary composition film on the substrate surface. PMMA and PFPE were the polymers used, while different-sized silica nanoparticles were employed for the production of the nanocomposite films. Examination of the coated and uncoated surfaces with profilometry and AFM and measurements of water contact angles reveal a pronounced effect of the surface roughness on water repellency. Especially in the case of nanocomposite coatings, the surfaces become super-hydrophobic. This result indicates that the nanoscale binary composition film scheme, which is characterized by its simplicity and low cost, is a suitable candidate for the water protection of stone-based monuments on large scale.

  13. Polymer-Silica nanoparticles composite films as protective coatings for stone-based monuments

    International Nuclear Information System (INIS)

    Manoudis, P; Papadopoulou, S; Karapanagiotis, I; Tsakalof, A; Zuburtikudis, I; Panayiotou, C

    2007-01-01

    The decrease of surface energy of mineral substrates similar to those used in many stone monuments of cultural heritage by the application of protective polymer coatings along with the simultaneous increase of their surface roughness can increase their ability to repel water substantially. In this work, the effect of artificially induced roughness on the water repellency of mineral substrates coated with protective polymer films was investigated. Natural marble samples or home made calcium carbonate blocks were tried as the mineral substrates. The roughness increase was achieved by mineral chemical etching or by creation of nanoscale binary composition film on the substrate surface. PMMA and PFPE were the polymers used, while different-sized silica nanoparticles were employed for the production of the nanocomposite films. Examination of the coated and uncoated surfaces with profilometry and AFM and measurements of water contact angles reveal a pronounced effect of the surface roughness on water repellency. Especially in the case of nanocomposite coatings, the surfaces become super-hydrophobic. This result indicates that the nanoscale binary composition film scheme, which is characterized by its simplicity and low cost, is a suitable candidate for the water protection of stone-based monuments on large scale

  14. In situ crystallization of b-oriented MFI films on plane and curved substrates coated with a mesoporous silica layer

    KAUST Repository

    Deng, Zhiyong

    2013-05-01

    A simple and reproducible method is presented for preparing b-oriented MFI films on plane (disc) and curved (hollow fiber) supports by in situ hydrothermal synthesis. A mesoporous silica (sub-)layer was pre-coated on the supports by dip coating followed by a rapid thermal calcination step (973 K during 1 min) to reduce the number of grain boundaries while keeping the hydrophilic behavior of silica. The role of the silica sub-layer is not only to smoothen the substrate surface, but also to provide a silica source to promote the nucleation and growth of zeolite crystals via a heterogeneous nucleation mechanism (zeolitization), and adsorb zeolite moieties generated in the synthesis solution via a homogeneous nucleation mechanism. A monolayer of b-oriented MFI crystals was obtained on both supports after 3 h synthesis time with a moderate degree of twinning on the surface. © 2013 Elsevier Ltd.

  15. X-ray spectroscopy study of electronic structure of laser-irradiated Au nanoparticles in a silica film

    International Nuclear Information System (INIS)

    Jonnard, P.; Bercegol, H.; Lamaignere, L.; Morreeuw, J.-P.; Rullier, J.-L.; Cottancin, E.; Pellarin, M.

    2005-01-01

    The electronic structure of gold nanoparticles embedded in a silica film is studied, both before and after irradiation at 355 nm by a laser. The Au 5d occupied valence states are observed by x-ray emission spectroscopy. They show that before irradiation the gold atoms are in metallic states within the nanoparticles. After irradiation with a fluence of 0.5 J/cm 2 , it is found that gold valence states are close to those of a metal-poor gold silicide; thanks to a comparison of the experimental Au 5d states with the calculated ones for gold silicides using the density-functional theory. The formation of such a compound is driven by the diffusion of the gold atoms into the silica film upon the laser irradiation. At higher fluence, 1 J/cm 2 , we find a higher percentage of metallic gold that could be attributed to annealing in the silica matrix

  16. Preparation, characterization and ex vivo evaluation of an orally disintegrating film formulation containing pyrazinamide

    CSIR Research Space (South Africa)

    Adeleke, Oluwatoyin A

    2015-10-01

    Full Text Available Vivo Evaluation of an Orally Disintegrating Film Formulation Containing Pyrazinamide O. A. Adeleke 1, P-C. Tsai 2, B. B. Michniak-Kohn 2 1 Council for Scientific and Industrial Research, 2 Rutgers - The State University of New Jersey Purpose...

  17. Formulation and characterization of polymeric films containing combinations of antiretrovirals (ARVs) for HIV prevention.

    Science.gov (United States)

    Akil, Ayman; Agashe, Hrushikesh; Dezzutti, Charlene S; Moncla, Bernard J; Hillier, Sharon L; Devlin, Brid; Shi, Yuan; Uranker, Kevin; Rohan, Lisa Cencia

    2015-02-01

    To develop polymeric films containing dual combinations of anti-HIV drug candidate tenofovir, maraviroc and dapivirine for vaginal application as topical microbicides. A solvent casting method was used to manufacture the films. Solid phase solubility was used to identify potential polymers for use in the film formulation. Physical and chemical properties (such as water content, puncture strength and in vitro release) and product stability were determined. The bioactivity of the film products against HIV was assessed using the TZM-bl assay and a cervical explant model. Polymers identified from the solid phase solubility study maintained tenofovir and maraviroc in an amorphous state and prevented drug crystallization. Three combination film products were developed using cellulose polymers and polyvinyl alcohol. The residual water content in all films was 50% of film drug content within 30 min. Stability testing confirmed that the combination film products were stable for 12 months at ambient temperature and 6 months under stressed conditions. Antiviral activity was confirmed in TZM-bl and cervical explant models. Polymeric films can be used as a stable dosage form for the delivery of antiretroviral combinations as microbicides.

  18. Growth of ordered silver nanoparticles in silica film mesostructured with a triblock copolymer PEO-PPO-PEO

    International Nuclear Information System (INIS)

    Bois, L.; Chassagneux, F.; Parola, S.; Bessueille, F.; Battie, Y.; Destouches, N.; Boukenter, A.; Moncoffre, N.; Toulhoat, N.

    2009-01-01

    Elaboration of mesostructured silica films with a triblock copolymer polyethylene oxide-polypropylene oxide-polyethylene oxide, (PEO-PPO-PEO) and controlled growth of silver nanoparticles in the mesostructure are described. The films are characterized using UV-visible optical absorption spectroscopy, TEM, AFM, SEM, X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS). Organized arrays of spherical silver nanoparticles with diameter between 5 and 8 nm have been obtained by NaBH 4 reduction. The size and the repartition of silver nanoparticles are controlled by the film mesostructure. The localization of silver nanoparticles exclusively in the upper-side part of the silica-block copolymer film is evidenced by RBS experiment. On the other hand, by using a thermal method, 40 nm long silver sticks can be obtained, by diffusion and coalescence of spherical particles in the silica-block copolymer layer. In this case, migration of silver particles toward the glass substrate-film interface is shown by the RBS experiment. - Graphical abstract: Growth of silver nanoparticles in a mesostructured block copolymer F127-silica film is performed either by a chemical route involving NaBH 4 reduction or by a thermal method. An array of spherical silver nanoparticles with 10 nm diameter on the upper-side of the mesostructured film or silver sticks long of 40 nm with a preferential orientation are obtained according to the method used. a: TEM image of the Fag5SiNB sample illustrating the silver nanoparticles array obtained by the chemical process; b: HR-TEM image of the Fag20Sid2 sample illustrating the silver nanosticks obtained by the thermal process.

  19. Structural evolution of nanoporous silica thin films studied by positron annihilation spectroscopy and Fourier transform infrared spectroscopy

    International Nuclear Information System (INIS)

    Patel, N; Mariazzi, S; Toniutti, L; Checchetto, R; Miotello, A; Dire, S; Brusa, R S

    2007-01-01

    Three series of silica thin films with thicknesses in the 300 nm range were deposited by spin coating on Si substrates using different compositions of the sol precursors. Film samples were thermally treated in static air at temperatures ranging from 300 to 900 deg. C. The effect of sol precursors and thermal treatment temperature on the film porosity was analysed by Fourier transform infrared (FTIR) spectroscopy, depth profiling with positron annihilation spectroscopy (DP-PAS) and the analysis of the capacitance-voltage (C-V) characteristic. The maximum of the total porosity was found to occur at a temperature of 600 deg. C when removal of porogen and OH groups was completed. Film densification due to the collapsing of the pores was observed after drying at 900 deg. C. DP-PAS provides evidence that the increase in the total porosity is related to a progressive increase in the pore size. The increase in the pore size never gives rise to the onset of connected porosity. In the silica film samples prepared using a low acidity sol precursor, the pore size is always lower than 1 nm. By increasing the acid catalyst ratio in the sol, larger pores are formed. Pores with size larger than 2.3 nm can be obtained by adding porogen to the sol. In each series of silica film samples the shift of the antisymmetric Si-O-Si transversal optical (TO 3 ) mode upon thermal treatment correlates with a change of the pore size as evidenced by DP-PAS analysis. The pore microstructure of the three series of silica films is different at all the examined treatment temperatures and depends on the composition of the precursor sol

  20. Structural evolution of nanoporous silica thin films studied by positron annihilation spectroscopy and Fourier transform infrared spectroscopy

    Science.gov (United States)

    Patel, N.; Mariazzi, S.; Toniutti, L.; Checchetto, R.; Miotello, A.; Dirè, S.; Brusa, R. S.

    2007-09-01

    Three series of silica thin films with thicknesses in the 300 nm range were deposited by spin coating on Si substrates using different compositions of the sol precursors. Film samples were thermally treated in static air at temperatures ranging from 300 to 900 °C. The effect of sol precursors and thermal treatment temperature on the film porosity was analysed by Fourier transform infrared (FTIR) spectroscopy, depth profiling with positron annihilation spectroscopy (DP-PAS) and the analysis of the capacitance-voltage (C-V) characteristic. The maximum of the total porosity was found to occur at a temperature of 600 °C when removal of porogen and OH groups was completed. Film densification due to the collapsing of the pores was observed after drying at 900 °C. DP-PAS provides evidence that the increase in the total porosity is related to a progressive increase in the pore size. The increase in the pore size never gives rise to the onset of connected porosity. In the silica film samples prepared using a low acidity sol precursor, the pore size is always lower than 1 nm. By increasing the acid catalyst ratio in the sol, larger pores are formed. Pores with size larger than 2.3 nm can be obtained by adding porogen to the sol. In each series of silica film samples the shift of the antisymmetric Si-O-Si transversal optical (TO3) mode upon thermal treatment correlates with a change of the pore size as evidenced by DP-PAS analysis. The pore microstructure of the three series of silica films is different at all the examined treatment temperatures and depends on the composition of the precursor sol.

  1. Relaxation of excited surface states of thin Ge-implanted silica films probed by OSEE spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zatsepin, A.F., E-mail: a.f.zatsepin@urfu.ru [Ural Federal University, Mira Street 19, 620002 Ekaterinburg (Russian Federation); Buntov, E.A.; Mikhailovich, A.P.; Slesarev, A.I. [Ural Federal University, Mira Street 19, 620002 Ekaterinburg (Russian Federation); Schmidt, B. [Research Center Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, P.O. Box 510119, D-01314 Dresden (Germany); Czarnowski, A. von; Fitting, Hans-Joachim [Institute of Physics, University of Rostock, Universitätsplatz 3, D-18051 Rostock (Germany)

    2016-01-15

    As an example of thin silica films, 30 nm SiO{sub 2}–Si heterostructures implanted with Ge{sup +} ions (10{sup 16} cm{sup −2} fluence) and rapid thermally annealed (RTA) at 950 °C are studied by means of optically stimulated electron emission (OSEE) in the spectral region of optical transparency for bulk silica. Quartz glass samples were used as references. Experimental data revealed a strong dependence between electron emission spectral features and RTA annealing time. The spectral contributions of both surface band tail states and interband transitions were clearly distinguished. The application of emission Urbach rule as well as Kane and Pässler equations allowed to analyze the OSEE spectra at different optical excitation energy ranges and to retrieve the important microstructural and energy parameters. The observed correlations between parameter values of Urbach- and Kane-related models suggest the implantation-induced conversion of both the vibrational subsystem and energy band of surface and interface electronic states. - Highlights: • Peculiarities of electron emission from excited surface states of SiO{sub 2}:Ge structures are studied. • Spectral contributions of surface band tails and interband transitions are distinguished. • Urbach and Kane models allow to examine photo-thermal emission mechanism. • Surface energy gap and structural disorder parameters are determined.

  2. Preparation of novel film-forming armoured latexes using silica nanoparticles as a pickering emulsion stabiliser.

    Science.gov (United States)

    Shiraz, Hana; Peake, Simon J; Davey, Tim; Cameron, Neil R; Tabor, Rico F

    2018-05-15

    Film-forming polymer latex particles of diameter acrylate (BA) as co-monomers, potassium persulphate (KPS) as an initiator and a commercially available colloidal nano-silica (Ludox®-TM40). It was found that pH control before polymerisation using methacrylic acid (MAA) facilitated the formation of armoured latexes, and mechanistic features of this process are discussed. An alternative, more robust protocol was developed whereby addition of vinyltriethoxysilane (VTES) to control wettability resulted in latexes completely armoured in colloidal nano-silica. The latexes were characterised using SEM, cryo-TEM and AFM imaging techniques. The mechanism behind the adsorption was investigated through surface pressure and contact angle measurements to understand the factors that influence this irreversible adsorption. Results indicate that nanoparticle attachment (but intriguingly not latex size) is dependent on particle wettability, providing new insight into the formation of nanoparticle-armoured latexes, along with opportunities for further development of diversely functionalized inorganic/organic polymer composite particles. Copyright © 2018 Elsevier Inc. All rights reserved.

  3. Tailoring of the Nanotexture of Mesoporous Silica Films and their Functionalized Derivatives for Selectively Harvesting Low Molecular Weight Protein

    Science.gov (United States)

    Hu, Ye; Bouamrani, Ali; Tasciotti, Ennio; Li, Li; Liu, Xuewu; Ferrari, Mauro

    2010-01-01

    We present a fast, efficient and reliable system based on mesoporous silica chips to specifically fractionate and enrich the low molecular weight proteome. Mesoporous silica thin films with tunable features at the nanoscale were fabricated using the triblock copolymer template pathway. Using different templates and concentrations in the precursor solution, various pore size distributions, pore structures and connectivity were obtained and applied for selective recovery of low mass proteins. In combination with mass spectrometry and statistic analysis, we demonstrated the correlation between the nanophase characteristics of the mesoporous silica thin films and the specificity and efficacy of low mass proteome harvesting. In addition, to overcome the limitations of the pre-functionalization method in polymer selection, plasma ashing was used for the first time for the treatment of the mesoporous silica surface prior to chemical modification. Surface charge modifications by different functional groups resulted in a selective capture of the low molecular weight proteins from serum sample. In conclusion our study demonstrates that the ability to tune the physico-chemical properties of mesoporous silica surfaces, for a selective enrichment of the low molecular weight proteome from complex biological fluids, has the potential to promote proteomic biomarker discovery. PMID:20014864

  4. Large third-order optical nonlinearity in vertically oriented mesoporous silica thin films embedded with Ag nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Min; Liu, Qiming, E-mail: qmliu@whu.edu.cn [Wuhan University, Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology (China)

    2016-12-15

    Taking advantage of the channel confinement of mesoporous films to prevent the agglomeration of Ag nanoparticles to achieve large third-order optical nonlinearity in amorphous materials, Ag-loaded composite mesoporous silica film was prepared by the electrochemical deposition method on ITO substrate. Ag ions were firstly transported into the channels of mesoporous film by the diffusion and binding force of channels, which were reduced to nanoparticles by applying suitable voltage. The existence and uniform distribution of Ag nanoparticles ranging in 1–10 nm in the mesoporous silica thin films were exhibited by UV spectrophotometer, X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) measurements. The third-order optical nonlinearity induced by Ag nanoparticles was studied by the Z-scan technique. Due to the local field surface plasmon resonance, the maximum third-order nonlinear optical susceptibility of Ag-loaded composite mesoporous silica film is 1.53×10{sup −10} esu, which is 1000 times larger than that of the Ag-contained chalcogenide glasses which showed large nonlinearity in amorphous materials.

  5. Low molecular weight protein enrichment on mesoporous silica thin films for biomarker discovery.

    Science.gov (United States)

    Fan, Jia; Gallagher, James W; Wu, Hung-Jen; Landry, Matthew G; Sakamoto, Jason; Ferrari, Mauro; Hu, Ye

    2012-04-17

    The identification of circulating biomarkers holds great potential for non invasive approaches in early diagnosis and prognosis, as well as for the monitoring of therapeutic efficiency.(1-3) The circulating low molecular weight proteome (LMWP) composed of small proteins shed from tissues and cells or peptide fragments derived from the proteolytic degradation of larger proteins, has been associated with the pathological condition in patients and likely reflects the state of disease.(4,5) Despite these potential clinical applications, the use of Mass Spectrometry (MS) to profile the LMWP from biological fluids has proven to be very challenging due to the large dynamic range of protein and peptide concentrations in serum.(6) Without sample pre-treatment, some of the more highly abundant proteins obscure the detection of low-abundance species in serum/plasma. Current proteomic-based approaches, such as two-dimensional polyacrylamide gel-electrophoresis (2D-PAGE) and shotgun proteomics methods are labor-intensive, low throughput and offer limited suitability for clinical applications.(7-9) Therefore, a more effective strategy is needed to isolate LMWP from blood and allow the high throughput screening of clinical samples. Here, we present a fast, efficient and reliable multi-fractionation system based on mesoporous silica chips to specifically target and enrich LMWP.(10,11) Mesoporous silica (MPS) thin films with tunable features at the nanoscale were fabricated using the triblock copolymer template pathway. Using different polymer templates and polymer concentrations in the precursor solution, various pore size distributions, pore structures, connectivity and surface properties were determined and applied for selective recovery of low mass proteins. The selective parsing of the enriched peptides into different subclasses according to their physicochemical properties will enhance the efficiency of recovery and detection of low abundance species. In combination with mass

  6. Electrochemical and dissolution studies on coated film and magnetite pellet in PDCA and NTA based formulations

    International Nuclear Information System (INIS)

    Srinivasan, M.P.; Sumathi, S.; Rangarajan, S.; Narasimhan, S.V.

    2000-01-01

    In water cooled nuclear reactors magnetite often exists as both mobile particulate protective film on the inner surface of the PHT system. To determine the mechanism and kinetics of dissolution from a film coated on carbon steel (CS) and magnetite pellet electrochemical measurements were carried out in 2,6-pyridine dicarboxylic acid (PDCA) and nitrilo-triacetic acid (NTA) based formulations containing ascorbic acid (AA) and citric acid (CA) at 28 degC and 60 degC. The solution redox potential arises based on the release of relative amounts of Fe 2+ and Fe 3+ . Complexation, adsorption and reduction affect the concentration of these species in solutions. On coated specimen, the pore size and rate of formation via auto reduction contribute to the observed potential. In PDCA based formulation higher percentage of magnetite dissolution with lower base metal corrosion was observed as compared to that in NTA based formulation. The base metal aided dissolution due to the pores and microcracks in the film (Auto reduction) was observed for coated film. The dominant role of surface adsorption characteristics of PDCA, AA and CA were evident in magnetite pellet dissolution studies. (author)

  7. SBA-15 mesoporous silica free-standing thin films containing copper ions bounded via propyl phosphonate units - preparation and characterization

    Energy Technology Data Exchange (ETDEWEB)

    Laskowski, Lukasz, E-mail: lukasz.laskowski@kik.pcz.pl [Czestochowa University of Technology, Institute of Computational Intelligence, Unit of Microelectronics and Nanotechnology, Al. Armii Krajowej 36, 42–201 Czestochowa (Poland); Laskowska, Magdalena, E-mail: magdalena.laskowska@onet.pl [H. Niewodniczanski Institute of Nuclear Physics, Polish Academy of Sciences, 31-342 Krakow, ul. Radzikowskiego 152 (Poland); Jelonkiewicz, Jerzy, E-mail: jerzy.jelonkiewicz@kik.pcz.pl [Czestochowa University of Technology, Institute of Computational Intelligence, Unit of Microelectronics and Nanotechnology, Al. Armii Krajowej 36, 42–201 Czestochowa (Poland); Dulski, Mateusz, E-mail: mateusz.dulski@us.edu.pl [University of Silesia, Faculty of Computer Science and Materials Science, Institute of Materials Science, Silesian Center for Education and Interdisciplinary Research, ul. 75 Pułku Piechoty 1A, 41–500 Chorzów (Poland); Wojtyniak, Marcin, E-mail: marcin.wojtyniak@us.edu.pl [University of Silesia, Institute of Physics, Silesian Center for Education and Interdisciplinary Research, ul. 75 Pułku Piechoty 1A, 41–500 Chorzów (Poland); Fitta, Magdalena, E-mail: magdalena.fitta@ifj.edu.pl [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, 31–342 Krakow, ul. Radzikowskiego 152 (Poland); Balanda, Maria, E-mail: Maria.Balanda@ifj.edu.pl [H. Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, 31–342 Krakow, ul. Radzikowskiego 152 (Poland)

    2016-09-15

    The SBA-15 silica thin films containing copper ions anchored inside channels via propyl phosphonate groups are investigated. Such materials were prepared in the form of thin films, with hexagonally arranged pores, laying rectilinear to the substrate surface. However, in the case of our thin films, their free standing form allowed for additional research possibilities, that are not obtainable for typical thin films on a substrate. The structural properties of the samples were investigated by X-ray reflectometry, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The molecular structure was examined by Raman spectroscopy supported by numerical simulations. Magnetic measurements (SQUID magnetometry and EPR spectroscopy) showed weak antiferromagnetic interactions between active units inside silica channels. Consequently, the pores arrangement was determined and the process of copper ions anchoring by propyl phosphonate groups was verified in unambiguous way. Moreover, the type of interactions between magnetic atoms was determined. - Highlights: • Functionalized free-standing SBA-15 thin films were synthesized for a first time. • Thin films synthesis procedure was described in details. • Structural properties of the films were thoroughly investigated and presented. • Magnetic properties of the novel material was investigated and presented.

  8. Silica Vesicle Nanovaccine Formulations Stimulate Long-Term Immune Responses to the Bovine Viral Diarrhoea Virus E2 Protein.

    Directory of Open Access Journals (Sweden)

    Karishma T Mody

    Full Text Available Bovine Viral Diarrhoea Virus (BVDV is one of the most serious pathogen, which causes tremendous economic loss to the cattle industry worldwide, meriting the development of improved subunit vaccines. Structural glycoprotein E2 is reported to be a major immunogenic determinant of BVDV virion. We have developed a novel hollow silica vesicles (SV based platform to administer BVDV-1 Escherichia coli-expressed optimised E2 (oE2 antigen as a nanovaccine formulation. The SV-140 vesicles (diameter 50 nm, wall thickness 6 nm, perforated by pores of entrance size 16 nm and total pore volume of 0.934 cm3 g(-1 have proven to be ideal candidates to load oE2 antigen and generate immune response. The current study for the first time demonstrates the ability of freeze-dried (FD as well as non-FD oE2/SV140 nanovaccine formulation to induce long-term balanced antibody and cell mediated memory responses for at least 6 months with a shortened dosing regimen of two doses in small animal model. The in vivo ability of oE2 (100 μg/SV-140 (500 μg and FD oE2 (100 μg/SV-140 (500 μg to induce long-term immunity was compared to immunisation with oE2 (100 μg together with the conventional adjuvant Quil-A from the Quillaja saponira (10 μg in mice. The oE2/SV-140 as well as the FD oE2/SV-140 nanovaccine generated oE2-specific antibody and cell mediated responses for up to six months post the final second immunisation. Significantly, the cell-mediated responses were consistently high in mice immunised with oE2/SV-140 (1,500 SFU/million cells at the six-month time point. Histopathology studies showed no morphological changes at the site of injection or in the different organs harvested from the mice immunised with 500 μg SV-140 nanovaccine compared to the unimmunised control. The platform has the potential for developing single dose vaccines without the requirement of cold chain storage for veterinary and human applications.

  9. Comparison of Dapivirine Vaginal Gel and Film Formulation Pharmacokinetics and Pharmacodynamics (FAME 02B).

    Science.gov (United States)

    Robinson, Jennifer A; Marzinke, Mark A; Bakshi, Rahul P; Fuchs, Edward J; Radebaugh, Christine L; Aung, Wutyi; Spiegel, Hans M L; Coleman, Jenell S; Rohan, Lisa C; Hendrix, Craig W

    2017-04-01

    While preexposure prophylaxis with oral tenofovir/emtricitabine reduces HIV acquisition rates, poor adherence to and acceptability of vaginal gels and the potential for evolving drug resistance have led to development of vaginal film formulations and other antiretroviral drugs, respectively, including the non-nucleoside reverse transcriptase inhibitor dapivirine. In this two-arm crossover study of a novel fast-dissolving dapivirine film and a previously studied semisolid dapivirine gel, 10 healthy women received a single 1.25 mg vaginal dose of each study product; one withdrew after the first dose. Clinical, pharmacokinetic, and antiviral pharmacodynamic assessments (ex vivo HIV-BaL challenge of tissue explants) were performed over 168 h postdose. Six of ten participants experienced mild to moderate adverse effects, similar between products, with no severe adverse events or adverse events attributed to study products. There were no statistically significant differences in plasma, cervicovaginal fluid (CVF), or cervical tissue dapivirine concentrations between the gel and film (all p > .05). CVF dapivirine concentrations were 1.5 and 6 log 10 greater than tissue and plasma concentrations, respectively (p dapivirine film and gel performed similarly in terms of tolerability, pharmacokinetics, and antiviral effect. Dapivirine film may provide an alternative to pharmacokinetically comparable dapivirine gel formulations. Effectiveness remains to be tested.

  10. Physical and antibacterial properties of edible films formulated with apple skin polyphenols.

    Science.gov (United States)

    Du, W-X; Olsen, C W; Avena-Bustillos, R J; Friedman, M; McHugh, T H

    2011-03-01

    Fruit and vegetable skins have polyphenolic compounds, terpenes, and phenols with antimicrobial and antioxidant activity. These flavoring plant essential oil components are generally regarded as safe. Edible films made from fruits or vegetables containing apple skin polyphenols have the potential to be used commercially to protect food against contamination by pathogenic bacteria. The main objective of this study was to evaluate physical properties as well as antimicrobial activities against Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica of apple skin polyphenols at 0% to 10% (w/w) concentrations in apple puree film-forming solutions formulated into edible films. Commercial apple skin polyphenol powder had a water activity of 0.44 and high total soluble phenolic compounds and antioxidant capacity (995.3 mg chlorogenic acid/100 g and 14.4 mg Trolox/g, respectively). Antimicrobial activities of edible film containing apple skin polyphenols were determined by the overlay method. Apple edible film with apple skin polyphenols was highly effective against L. monocytogenes. The minimum concentration need to inactive L. monocytogenes was 1.5%. However, apple skin polyphenols did not show any antimicrobial effect against E. coli O157:H7 and S. enterica even at 10% level. The presence of apple skin polyphenols reduced water vapor permeability of films. Apple skin polyphenols increased elongation of films and darkened the color of films. The results of the present study show that apple skin polyphenols can be used to prepare apple-based antimicrobial edible films with good physical properties for food applications by direct contact.

  11. Formulation and Evaluation of Edible Film from Basil Leaves Extract (Ocimum americanum L. as Mouth Freshener

    Directory of Open Access Journals (Sweden)

    Fifi Harmely

    2015-02-01

    Full Text Available A research on formulation of edible film from basil leaves extract as mouth freshener has been done. The extract of basil leaves were used in various concentrations which are 2.5%, 5% and 7.5%. The products were evaluated for some parameters such as organoleptic, friability, drying shrinkage, pH, thickness, flavonoid contents and respondents preference. The results of evaluation showed that edible filmsfrom basil leaves extract meet requirements as required by Standard Nasional Indonesia (SNI and have such quality as product in the market. Statistical analysis using Kruskal Wallis test showed that respondents preferred for the F0 formulation in term of their appearance and taste while as mouth freshener, respondents preferred the F3 formulation.

  12. Quality by design approach for optimizing the formulation and physical properties of extemporaneously prepared orodispersible films.

    Science.gov (United States)

    Visser, J Carolina; Dohmen, Willem M C; Hinrichs, Wouter L J; Breitkreutz, Jörg; Frijlink, Henderik W; Woerdenbag, Herman J

    2015-05-15

    The quality by design (QbD) approach was applied for optimizing the formulation of extemporaneously prepared orodispersible films (ODFs) using Design-Expert® Software. The starting formulation was based on earlier experiments and contained the film forming agents hypromellose and carbomer 974P and the plasticizer glycerol (Visser et al., 2015). Trometamol and disodium EDTA were added to stabilize the solution. To optimize this formulation a quality target product profile was established in which critical quality attributes (CQAs) such as mechanical properties and disintegration time were defined and quantified. As critical process parameters (CPP) that were evaluated for their effect on the CQAs the percentage of hypromellose and the percentage of glycerol as well as the drying time were chosen. Response surface methodology (RMS) was used to evaluate the effects of the CPPs on the CQAs of the final product. The main factor affecting tensile strength and Young's modulus was the percentage of glycerol. Elongation at break was mainly influenced by the drying temperature. Disintegration time was found to be sensitive to the percentage of hypromellose. From the results a design space could be created. As long as the formulation and process variables remain within this design space, a product is obtained with desired characteristics and that meets all set quality requirements. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Formulation, development and characterization of mucoadhesive film for treatment of vaginal candidiasis.

    Science.gov (United States)

    Mishra, Renuka; Joshi, Priyanka; Mehta, Tejal

    2016-01-01

    The objective of the present investigation was formulation, optimization and characterization of mucoadhesive film of clotrimazole (CT) which is patient-convenient and provides an effective alternative for the treatment of vaginal candidiasis. CT is an antimycotic drug applied locally for the treatment of vaginal candidiasis. Mucoadhesive vaginal films were prepared by solvent casting technique using hydroxyl propylcellulose and sodium alginate as polymers. Propylene glycol and polyethylene glycol-400 were evaluated as plasticizers. The mucoadhesive vaginal films were evaluated for percentage elongation, tensile strength, folding endurance, drug content, in vitro disintegration time, in vitro dissolution study, swelling index, bioadhesive strength, and diffusion study. Among various permeation enhancers used, isopropyl myristate was found to be suitable. To evaluate the role of the concentration of permeation enhancer and concentration of polymers in the optimization of mucoadhesive vaginal film, 3(2) full factorial design was employed. Optimized batch showed in vitro disintegration time, 18 min; drug content, 99.83%; and tensile strength, 502.1 g/mm(2). In vitro diffusion study showed that 77% drug diffusion occurred in 6 h. This batch was further evaluated by scanning electron microscopy indicating uniformity of the film. In vitro Lactobacillus inhibition and in vitro antifungal activity of optimized batch showed an inhibitory effect against Candida albicans and no effect on Lactobacillus, which is a normal component of vaginal flora. Mucoadhesive vaginal film of CT is an effective dosage form for the treatment of vaginal candidiasis.

  14. Replication of butterfly wing and natural lotus leaf structures by nanoimprint on silica sol-gel films

    International Nuclear Information System (INIS)

    Saison, Tamar; Peroz, Christophe; Chauveau, Vanessa; Sondergard, Elin; Arribart, Herve; Berthier, Serge

    2008-01-01

    An original and low cost method for the fabrication of patterned surfaces bioinspired from butterfly wings and lotus leaves is presented. Silica-based sol-gel films are thermally imprinted from elastomeric molds to produce stable structures with superhydrophobicity values as high as 160 deg. water contact angle. The biomimetic surfaces are demonstrated to be tuned from superhydrophobic to superhydrophilic by annealing between 200 deg. C and 500 deg. C

  15. Replication of butterfly wing and natural lotus leaf structures by nanoimprint on silica sol-gel films

    Energy Technology Data Exchange (ETDEWEB)

    Saison, Tamar; Peroz, Christophe; Chauveau, Vanessa; Sondergard, Elin; Arribart, Herve [Unite mixte CNRS/Saint Gobain Saint Gobain Recherche, BP135, 93303 Aubervilliers (France); Berthier, Serge [Institut des Nanosciences de Paris, UMR 7588, CNRS, Universite Pierre et Marie Curie-Paris 6, 140 rue Lourmel, 75015 Paris (France)], E-mail: cperoz@lbl.gov

    2008-12-01

    An original and low cost method for the fabrication of patterned surfaces bioinspired from butterfly wings and lotus leaves is presented. Silica-based sol-gel films are thermally imprinted from elastomeric molds to produce stable structures with superhydrophobicity values as high as 160 deg. water contact angle. The biomimetic surfaces are demonstrated to be tuned from superhydrophobic to superhydrophilic by annealing between 200 deg. C and 500 deg. C.

  16. Casein Films: The Effects of Formulation, Environmental Conditions and the Addition of Citric Pectin on the Structure and Mechanical Properties

    Directory of Open Access Journals (Sweden)

    Laetitia M. Bonnaillie

    2014-07-01

    Full Text Available Thin casein films for food packaging applications reportedly possess good strength and low oxygen permeability, but low elasticity and high sensitivity to moisture. Modifying the films to target specific behaviors depending on environmental conditions can enable a variety of commercial applications for casein-based films. The mechanical properties of solvent-cast (15% solids calcium-caseinate/glycerol films (CaCas:Gly ratio of 3:1 were characterized as a function of processing and environmental conditions, including film thickness, solution formulation and ambient humidity (from 22% to 70% relative humidity (RH at ~20 °C. At constant RH, the elongation at break (EAB had a strong positive dependence on the film thickness. When RH increased, the tensile strength (TS and modulus (E decreased approximately linearly, while EAB increased. From 0.05% to 1% (w/w of citric pectin (CP was then incorporated into CaCas/Gly films following seven different formulations (mixing sequences, to alter the protein network and to evaluate the effects of CP on the tensile properties of CaCas/Gly/CP films. At constant film thickness and ~60% RH, the addition of 0.1% or 1.0% CP to the films considerably increased or decreased EAB, TS and E in different directions and to different extents, depending on the formulation, while optical micrographs also showed vastly differing network configurations, suggesting complex formulation- and stoichiometry-dependent casein-pectin interactions within the dried films. Depending on the desired film properties and utilization conditions, pectin may be a useful addition to casein film formulations for food packaging applications.

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

    Science.gov (United States)

    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.

  18. Effect of Addition of Colloidal Silica to Films of Polyimide, Polyvinylpyridine, Polystyrene, and Polymethylmethacrylate Nano-Composites

    Directory of Open Access Journals (Sweden)

    Soliman Abdalla

    2016-02-01

    Full Text Available Nano-composite films have been the subject of extensive work for developing the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nanoparticle size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that forms the insulating film between the 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 four highly pure amorphous polymer films: polymethyl methacrylate (PMMA, polystyrene, polyimide and poly-4-vinylpyridine. Comparison between the dielectric properties of these polymers has revealed that the higher breakdown 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.

  19. Mucoadhesive Hydrogel Films of Econazole Nitrate: Formulation and Optimization Using Factorial Design

    Directory of Open Access Journals (Sweden)

    Balaram Gajra

    2014-01-01

    Full Text Available The mucoadhesive hydrogel film was prepared and optimized for the purpose of local drug delivery to oral cavity for the treatment of oral Candidiasis. The mucoadhesive hydrogel film was prepared with the poly(vinyl alcohol by freeze/thaw crosslinking technique. 32 full factorial design was employed to optimize the formulation. Number of freeze/thaw cycles (4, 6, and 8 cycles and the concentration of the poly(vinyl alcohol (10, 15, and 20% were used as the independent variables whereas time required for 50% drug release, cumulative percent of drug release at 8th hour, and “k” of zero order equation were used as the dependent variables. The films were evaluated for mucoadhesive strength, in vitro residence time, swelling study, in vitro drug release, and effectiveness against Candida albicans. The concentration of poly(vinyl alcohol and the number of freeze/thaw cycles both decrease the drug release rate. Mucoadhesive hydrogel film with 15% poly(vinyl alcohol and 7 freeze/thaw cycles was optimized. The optimized batch exhibited the sustained release of drug and the antifungal studies revealed that the drug released from the film could inhibit the growth of Candida albicans for 12 hours.

  20. Form(ulating Mistrust in the State in the 1990s’ Slovak Live-Action Films

    Directory of Open Access Journals (Sweden)

    Dudková Jana

    2017-09-01

    Full Text Available The text deals with the ways in which Slovak live-action films made in the 1990s introduced the topic of mistrust in the State and in its institutions. Using specific examples, the text demonstrates that such mistrust was not primarily a critical attitude, but rather consisted of two basic forms of rejection. On the one hand, live-action films made for cinema often promoted the post-modern principle of a “relative” truth, presenting a lifestyle with minimal ties to the State, sometimes also formulating a mistrust in specific state institutions (the police, state-run artistic institutions, education system by means of irony. On the other hand, films made for state television frequently drew attention to corruption in state organisations and the fact it was usually being generally accepted as a status that did not need to be analysed. In both cases, the message of the 1990s was carried onto the next millennium, and can eventually be interpreted as a way of solidifying the discourse of mistrust that we perceive in contemporary Slovak film for cinemas and television.

  1. Submicrometric gratings fabrication from photosensitive organo-silica-hafnia thin films elaborated by sol-gel processing

    Energy Technology Data Exchange (ETDEWEB)

    Franc, Janyce [Universite de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France); Barnier, Vincent, E-mail: barnier@emse.fr [Ecole Nationale Superieure des Mines, SMS-EMSE, CNRS:UMR 5146, LCG, F-42023 Saint-Etienne (France); Vocanson, Francis, E-mail: francis.vocanson@univ-st-etienne.fr [Universite de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France); Gamet, Emilie; Lesage, Maryline [Universite de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France); Jamon, Damien [Universite de Lyon, F-42023 Saint-Etienne (France); Laboratoire Claude Chappe, Telecom Saint-Etienne, 42000 Saint-Etienne Cedex 2 (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France); Jourlin, Yves [Universite de Lyon, F-42023 Saint-Etienne (France); CNRS, UMR 5516, Laboratoire Hubert Curien, 42023 Saint-Etienne (France); Universite de Saint-Etienne, Jean-Monnet, F-42023 Saint-Etienne (France)

    2012-07-31

    The aim of this study is the elaboration of a high index sol-gel material in order to prepare submicrometric grating. The gratings were obtained after few seconds of UV exposure in one step using an organically modified silica-hafnia matrix. The chemical composition of thin films after UV and annealing treatments were studied using Fourier Transform Infrared Spectroscopy and X-Ray Photoelectron Spectroscopy. The study of optical properties revealed that the annealed films are transparent from 200 to 1000 nm and have a refractive index from 1.550 to 1.701 depending on the hafnium concentration. - Highlights: Black-Right-Pointing-Pointer Silica-hafnia matrix with high refractive index was prepared using sol-gel process. Black-Right-Pointing-Pointer Organic and inorganic networks formation of thin films was investigated. Black-Right-Pointing-Pointer Optical properties are influenced by annealing treatment and initial hafnium amount. Black-Right-Pointing-Pointer The use of high Si:Hf molar ratio can lead to a loss transmittance below 300 nm. Black-Right-Pointing-Pointer Submicrometric grating period can be prepared using a holographic method.

  2. Quality by Design approach for studying the impact of formulation and process variables on product quality of oral disintegrating films.

    Science.gov (United States)

    Mazumder, Sonal; Pavurala, Naresh; Manda, Prashanth; Xu, Xiaoming; Cruz, Celia N; Krishnaiah, Yellela S R

    2017-07-15

    The present investigation was carried out to understand the impact of formulation and process variables on the quality of oral disintegrating films (ODF) using Quality by Design (QbD) approach. Lamotrigine (LMT) was used as a model drug. Formulation variable was plasticizer to film former ratio and process variables were drying temperature, air flow rate in the drying chamber, drying time and wet coat thickness of the film. A Definitive Screening Design of Experiments (DoE) was used to identify and classify the critical formulation and process variables impacting critical quality attributes (CQA). A total of 14 laboratory-scale DoE formulations were prepared and evaluated for mechanical properties (%elongation at break, yield stress, Young's modulus, folding endurance) and other CQA (dry thickness, disintegration time, dissolution rate, moisture content, moisture uptake, drug assay and drug content uniformity). The main factors affecting mechanical properties were plasticizer to film former ratio and drying temperature. Dissolution rate was found to be sensitive to air flow rate during drying and plasticizer to film former ratio. Data were analyzed for elucidating interactions between different variables, rank ordering the critical materials attributes (CMA) and critical process parameters (CPP), and for providing a predictive model for the process. Results suggested that plasticizer to film former ratio and process controls on drying are critical to manufacture LMT ODF with the desired CQA. Published by Elsevier B.V.

  3. Ordered and disordered evolution of the pore mesostructure in hybrid silica anti-reflective films obtained by one-pot self-assembly method

    Energy Technology Data Exchange (ETDEWEB)

    Ghazzal, Mohamed N., E-mail: g_nawfel@yahoo.fr; Debecker, Damien P.; Gaigneaux, Eric M.

    2016-07-29

    Hybrid mesoporous silica films were prepared in acid-catalysed medium using a one-pot self-assembly method. A gradual content of methyl groups was introduced into the inorganic framework by co-condensation of tetraethyl orthosilicate and methyltriethoxysilane. To better understand how the ordered and disordered transition occurs in mesoporous hybrid organosilica sytem as function of the MTES molar ratio in the starting solution, textural, chemical and optical properties of the films were studied by transmission electronic microscopy (TEM), grazing-incident small angle X-ray scattering (GISAXS), transmission Fourier transformed infrared (FTIR) and UV–visible spectroscopy. Increasing the loading of the incorporated organic groups (up to 40% in the starting solution) led simultaneously to a disorganization of the pore mesostructure and a reduction in the pore diameter. Concomitantly, a disordered domain of the silica rings in the walls was observed, which created bond strains in the silica wall contributing also to the disorganization of the pore mesostructure. Furthermore, an optimal MTES content was identified in order to obtain antireflection coatings, exhibiting low reflection in the visible range. - Highlights: • Mesoporous hybrid silica films where prepared by one-pot co-condensation of MTES and TEOS. • Ordered and disordered mesostructures were studied as function as variable MTES molar ratio. • A rearrangement of the silica cyclic species occurred as the molar ratio of MTES increases. • Transmittance of the silica coatings is affected by the MTES molar ratio.

  4. Controlling pore morphology and properties of nanoporous silica films using the different architecture PS-b-P2VP as a template.

    Science.gov (United States)

    Yu, Yang-Yen; Chien, Wen-Chen; Chen, Shih-Ting

    2010-07-01

    Nanoporous silica films were prepared through the templating of amphiphilic block copolymer, poly(styrene-2-vinyl pyridine) (PS-b-P2VP), and monodispersed colloidal silica nanoparticles. The experimental and theoretical studies suggested that the intermolecular hydrogen bonding existes between the colloidal silica nanoparticles and PS-b-P2VP. The effects of the loading ratio and P2VP chain length on the morphology and properties of the prepared nanoporous silica films were investigated. TEM and AFM studies showed that the uniform pore size could be achieved and the pore size increased with increasing porogen loading. The refractive index and dielectric constant of the prepared nanoporous films decreased with an increase in PS-b-P2VP loading. On the other hand, the porosity increased with an increasing PS-b-P2VP loading. This study demonstrated a methodology to control pore morphology and properties of the nanoporous silica films through the templating of PS-b-P2VP.

  5. FORMULATION AND TECHNOLOGY DEVELOPMENT OF HERBAL PHENOLIC BIOPOLYMER-CONTAINING FILMS FOR BURN TREATMENT.

    Science.gov (United States)

    Gokadze, S; Barbakadze, V; Mulkijanyan, K; Bakuridze, A; Bakuridze, L

    2017-06-01

    Application of phytofilms based on biosolublepolymers is considered as a prospectivemethod for burn treatment . Herbal remedies contain biologically active substances, that are relatively less toxic, do not cause skin irritation or allergic reactions and, importantly, affectstrains of the microorganisms and viruses resistant to antibiotics and synthetic drugs. Nowadays, the advantages are given to such burn healing drugs, which along with high specific efficacy, have analgesic, anti-inflammatory and antimicrobial effects, and don't irritate the tissues. The mentioned peculiarities are characteristic for a new herbal phenolic biopolymer poly[3-(3,4-dihydroxyphenyl) glyceric acid](PDGA), isolated from the roots and stems of different comfrey species . The aim of the study was the development of the formulation and technology of biosoluble films for burn treatment on the basis of PDGA. The optimal content of phytofilm for burn healing was selected on the basis of the biopharmaceutical study results. The impact of the film-former on the quality, adhesion and moisture absorption of the phytofilmhas been studied. The optimal degree of the phytofilm moisture, determining its high adhesive properties,was established. The film prepared on the basis of sodium alginate, with 30.4% humidity, demonstrated the greatest adhesion strength. After investigation of the PDGA release it was found, that the hydrophilic bases such as: sodium carboxymethyl-cellulose (69.2%) andsodium alginate (78,65%) appeared to be optimal among the others. At the same time, taking into consideration the disadvantages of sodium carboxymethyl-cellulose (tautening effect on burnt surface, relatively low stability), a film based on sodium alginate has been chosen. The manufacturing technology for obtaining PDGA-containing phytofilm by casting is proposed. Theshelf-lifeofproposedPDGA-containingphytofilmis 2 years.

  6. Voltammetric Determination of Lead (II) and Cadmium (II) Using a Bismuth Film Electrode Modified with Mesoporous Silica Nanoparticles

    International Nuclear Information System (INIS)

    Yang, Die; Wang, Liang; Chen, Zuliang; Megharaj, Mallavarapu; Naidu, Ravi

    2014-01-01

    A new chemically modified glassy carbon electrode based on bismuth film coated mesoporous silica nanoparticles was developed and evaluated for reliable quantification of trace Pb 2+ and Cd 2+ by anodic stripping square wave voltammetry in natural water samples. Compared with conventional bismuth film electrodes or bismuth nanoparticles modified electrodes, this electrode exhibited significantly improved sensitivity and stability for Pb 2+ and Cd 2+ detection. The key experimental parameters related to the fabrication of the electrode and the voltammetric measurements were optimized on the basis of the stripping signals, where the peak currents increased linearly with the metal concentrations in a range of 2-150 μg L −1 with a detect limit of 0.2 μg L −1 for Pb 2+ , and 0.6 μg L −1 for Cd 2+ for 120s deposition. Good reproducibility was achieved on both single and equally prepared electrodes. In addition, scanning electron microscopy reveals that fibril-like bismuth structures were formed on silica nanoparticles, which could be responsible for the improved voltammetric performance due to the enhanced surface area. Finally, the developed electrode was applied to determine Pb 2+ and Cd 2+ in water samples, indicating that this electrode was sensitive, reliable and effective for the simultaneous determination of Pb 2+ and Cd 2+

  7. One-Pot Fabrication of Antireflective/Antibacterial Dual-Function Ag NP-Containing Mesoporous Silica Thin Films.

    Science.gov (United States)

    Wang, Kaikai; He, Junhui

    2018-04-04

    Thin films that integrate antireflective and antibacterial dual functions are not only scientifically interesting but also highly desired in many practical applications. Unfortunately, very few studies have been devoted to the preparation of thin films with both antireflective and antibacterial properties. In this study, mesoporous silica (MSiO 2 ) thin films with uniformly dispersed Ag nanoparticles (Ag NPs) were prepared through a one-pot process, which simultaneously shows high transmittance, excellent antibacterial activity, and mechanical robustness. The optimal thin-film-coated glass substrate demonstrates a maximum transmittance of 98.8% and an average transmittance of 97.1%, respectively, in the spectral range of 400-800 nm. The growth and multiplication of typical bacteria, Escherichia coli ( E. coli), were effectively inhibited on the coated glass. Pencil hardness test, tape adhesion test, and sponge washing test showed favorable mechanical robustness with 5H pencil hardness, 5A grade adhesion, and functional durability of the coating, which promises great potential for applications in various touch screens, windows for hygiene environments, and optical apparatuses for medical uses such as endoscope, and so on.

  8. Nanotexture Optimization by Oxygen Plasma of Mesoporous Silica Thin Film for Enrichment of Low Molecular Weight Peptides Captured from Human Serum

    Science.gov (United States)

    Hu, Ye; Peng, Yang; Brousseau, Louis; Bouamrani, Ali; Liu, Xuewu; Ferrari, Mauro

    2010-01-01

    This study investigated the optimization of mesoporous silica thin films by nanotexturing using oxygen plasma versus thermal oxidation. Calcination in oxygen plasma provides superior control over pore formation with regard to the pore surface and higher fidelity to the structure of the polymer template. The resulting porous film offers an ideal substrate for the selective partitioning of peptides from complex mixtures. The improved chemico-physical characteristics of porous thin films (pore size distribution, nanostructure, surface properties and pore connectivity) were systematically characterized with XRD, Ellipsometry, FTIR, TEM and N2 adsorption/desorption. The enrichment of low molecular weight proteins captured from human serum on mesoporous silica thin films fabricated by both methodologies were investigated by comparison of their MALDI-TOF MS profiles. This novel on-chip fractionation technology offers advantages in recovering the low molecular weight peptides from human serum, which has been recognized as an informative resource for early diagnosis of cancer and other diseases. PMID:21179395

  9. Sol-gel approach to the novel organic-inorganic hybrid composite films with ternary europium complex covalently bonded with silica matrix

    International Nuclear Information System (INIS)

    Dong Dewen; Yang Yongsheng; Jiang Bingzheng

    2006-01-01

    Novel organic-inorganic hybrid composite films with ternary lanthanide complex covalently bonded with silica matrix were prepared in situ via co-ordination of N-(3-propyltriethoxysilane)-4-carboxyphthalimide (TAT) and 1,10-phenanthroline (Phen) with europium ion (Eu 3+ ) during a sol-gel approach and characterized by the means of spectrofluorimeter, phosphorimeter and infrared spectrophotometer (FTIR). The resulting transparent films showed improved photophysical properties, i.e. increased luminescence intensity and longer luminescence lifetime, compared with the corresponding binary composite films without Phen. All the results revealed that the intense luminescence of the composite film was attributed to the efficient energy transfer from ligands, especially Phen, to chelated Eu 3+ and the reduced non-radiation through the rigid silica matrix and 'site isolation'

  10. Preparation and characterization of silica/fluorinated acrylate copolymers hybrid films and the investigation of their icephobicity

    International Nuclear Information System (INIS)

    Huang Yanfen; Hu Mingjie; Yi Shengping; Liu Xinghai; Li Houbin; Huang Chi; Luo Yunbai; Li Yan

    2012-01-01

    Inexpensive hydrophobic and icephobic coatings and films were obtained by a simple method. These coatings were prepared by mixing silica sol and fluorinated acrylate copolymers. There was a phase separation process in the film-forming which can provide the excellent performance. Small amount (about 2 wt.%) of fluorinated (methyl) acrylate was used in all of these coatings. The coatings were eco-friendly by using ethanol as the solvent system. Scanning electron microscopy, atomic force microscope, energy dispersive X-ray fluorescence spectrometer, water contact angle, thermal gravimetric analysis and tests of adhesion and hardness had been performed to characterize the morphological feature, chemical composition, hydrophobicity and icephobicity of the surface, thermal stability and mechanical properties of the coatings. The results showed that the films had good hydrophobicity, high thermal stability and excellent mechanical properties of adhesion strength and pencil hardness. Furthermore, by testing their properties of delaying water droplet from icing, it was found that ice formation was delayed for 90 min compared with the glass surface at − 5.6 °C. The hybrid coatings may be suitable for large-scale and practical application owing to its flexibility and simplicity. - Highlights: ► Coatings were prepared by mixing fluorinated acrylate copolymer and silica. ► Mechanical properties and anti-icing performance of the coatings were examined. ► Water contact angle increased with raising SiO 2 (sol)/monomers weight ratio. ► Ice formation was delayed for 90 min at − 5.6 °C.

  11. Successful implementation of the stepwise layer-by-layer growth of MOF thin films on confined surfaces: Mesoporous silica foam as a first case study

    KAUST Repository

    Shekhah, Osama; Fu, Lei; Sougrat, Rachid; Belmabkhout, Youssef; Cairns, Amy; Giannelis, Emmanuel P.; Eddaoudi, Mohamed

    2012-01-01

    Here we report the successful growth of highly crystalline homogeneous MOF thin films of HKUST-1 and ZIF-8 on mesoporous silica foam, by employing a layer-by-layer (LBL) method. The ability to control and direct the growth of MOF thin films on confined surfaces, using the stepwise LBL method, paves the way for new prospective applications of such hybrid systems. © 2012 The Royal Society of Chemistry.

  12. Organic-inorganic nanocomposite films made from polyurethane dispersions and colloidal silica particles

    Czech Academy of Sciences Publication Activity Database

    Serkis, Magdalena; Špírková, Milena; Kredatusová, Jana; Hodan, Jiří; Bureš, R.

    2016-01-01

    Roč. 23, č. 2 (2016), s. 157-173 ISSN 0927-6440 R&D Projects: GA ČR(CZ) GA13-06700S Institutional support: RVO:61389013 Keywords : polyurethane dispersion * colloidal silica * composites Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.083, year: 2016

  13. Preparation and characterization of bimetallic catalysts supported on mesoporous silica films

    NARCIS (Netherlands)

    Muraza, O.; Rebrov, E.V.; Khimyak, T.; Johnson, B.F.G.; Kooyman, P.J.; Lafont, U.; Albouy, P.A.; Croon, de M.H.J.M.; Schouten, J.C.

    2006-01-01

    Thin (300–1000 nm) mesoporous silica coatings with hexagonal and cubic mesostructure have been prepared on Pyrex® 7740 borosilicate glass substrates by the evaporation induced self assembly assisted sol-gel route. Prior to the synthesis, a 50 nm TiO2 layer has been deposited on the substate by

  14. Silica in situ enhanced PVA/chitosan biodegradable films for food packages.

    Science.gov (United States)

    Yu, Zhen; Li, Baoqiang; Chu, Jiayu; Zhang, Peifeng

    2018-03-15

    Non-degradable plastic food packages threaten the security of environment. The cost-effective and biodegradable polymer films with good mechanical properties and low permeability are very important for food packages. Among of biodegradable polymers, PVA/chitosan (CS) biodegradable films have attracted considerable attention because of feasible film forming ability. However, PVA/CS biodegradable films suffered from poor mechanical properties. To improve mechanical properties of PVA/CS biodegradable films, we developed SiO 2 in situ to enhance PVA/CS biodegradable films via hydrolysis of sodium metasilicate in presence of PVA and chitosan solution. The tensile strength of PVA/CS biodegradable films was improved 45% when 0.6 wt.% SiO 2 was incorporated into the films. Weight loss of PVA/CS biodegradable films was 60% after 30 days in the soil. The permeability of oxygen and moisture of PVA/CS biodegradable films was reduced by 25.6% and 10.2%, respectively. SiO 2 in situ enhanced PVA/CS biodegradable films possessed not only excellent mechanical properties, but also barrier of oxygen and water for food packages to extend the perseveration time. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Mechanical properties and antibiotic release characteristics of poly(methyl methacrylate)-based bone cement formulated with mesoporous silica nanoparticles.

    Science.gov (United States)

    Letchmanan, Kumaran; Shen, Shou-Cang; Ng, Wai Kiong; Kingshuk, Poddar; Shi, Zhilong; Wang, Wilson; Tan, Reginald B H

    2017-08-01

    The influence of mesoporous silica nanoparticles (MSNs) loaded with antibiotics on the mechanical properties of functional poly(methyl methacrylate)-(PMMA) based bone cements is investigated. The incorporation of MSNs to the bone cements (8.15wt%) shows no detrimental effects on the biomechanical properties of the freshly solidified bone cements. Importantly, there are no significant changes in the compression strength and bending modulus up to 6 months of aging in PBS buffer solution. The preserved mechanical properties of MSN-functionalized bone cements is attributed to the unchanged microstructures of the cements, as more than 96% of MSNs remains in the bone cement matrix to support the cement structures after 6 months of aging. In addition, the MSN-functionalized bone cements are able to increase the drug release of gentamicin (GTMC) significantly as compared with commercially available antibiotic-loaded bone cements. It can be attributed to the loaded nano-sized MSNs with uniform pore channels which build up an effective nano-network path enable the diffusion and extended release of GTMC. The combination of excellent mechanical properties and sustainable drug delivery efficiency demonstrates the potential applicability of MSN-functionalized PMMA bone cements for orthopedic surgery to prevent post-surgery infection. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Alkali passivation mechanism of sol-gel derived TiO2-SiO2 films coated on soda-lime-silica glass substrates

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, A; Matsuno, Y; Katayama, S; Tsuno, T [Nippon Steel Glass Co. Ltd., Tokyo (Japan); Toge, N; Minami, T [University of Osaka Prefecture, Osaka (Japan). College of Engineering

    1992-09-01

    TiO2-SiO2 films prepared by the sol-gel method serves as an effective alkali passivation layer on a soda-lime-silica glass substrate and the film is superior to a sol-gel derived pure SiO2 film from the view point of weathering resistance improvement. To clarify the reason, alkali passivation mechanism of sol-gel derived TiO2-SiO2 glass films with different TiO2 contents coated on a soda-lime-silica glass substrate was studied by SIMS (secondary ion mass spectroscopy) and XPS (X-ray photoelectron spectroscopy) analyses, and compared with the results of a sol-gel derived pure SiO2 film. As a result, the following conclusions were obtained: An increase in TiO2 content in the TiO2 SiO2 film increases the sodium concentration in the film, which was induced by sodium migration from the glass substrate during the heat-treatment. Because of the presence of sodium the TiO2 -SiO2 films serve not as a barrier but as an effective getter of alkali ions and thereby effectively improve the weathering resistance Of the glass substrate. 10 refs., 6 figs.

  17. Perhydropolysilazane-derived silica-polymethylmethacrylate hybrid thin films highly doped with spiropyran: Effects of polymethylmethacrylate on the hardness, chemical durability and photochromic properties

    International Nuclear Information System (INIS)

    Yamano, Akihiro; Kozuka, Hiromitsu

    2011-01-01

    Polymethylmethacrylate (PMMA)-perhydropolysilazane (PHPS) hybrid thin films doped with spiropyran were prepared by spin-coating, which were then converted into 0.26-1.7 μm thick, spiropyran-doped PMMA-silica hybrid films by exposure treatment over aqueous ammonia. The spiropyran/(spiropyran + PHPS + PMMA) mass ratio was fixed at a high value of 0.2 so that the films exhibit visual photochromic changes in color, while the PMMA/(PMMA + PHPS) mass ratio, r, was varied. The spiropyran molecules in the as-prepared films were in merocyanine (MC) and spiro (SP) forms, with and without an optical absorption at 500 nm, at low (r ≤ 0.2) and high (r ≥ 0.4) PMMA contents, respectively. When PMMA content r was increased from 0 to 0.2, the degree of the MC-to-SP conversion on vis light illumination was enhanced, while at higher r's the spiropyran molecules underwent photodegradation. When the silica film (r = 0) was soaked in xylene under vis light, the spiropyran molecules were almost totally leached out, while not on soaking in the dark. On the other hand, no leaching occurred for the film of r = 0.2 either in the presence or absence of vis light. These suggest that the introduction of PMMA is effective in improving the chemical durability of the films, while the silica film (r = 0) is an interesting material with a photoresponsive controlled-release ability. The pencil hardness of the films decreased with increasing PMMA content, but remained over 9H at r ≤ 0.4.

  18. Carbon film resistor electrode for amperometric determination of acetaminophen in pharmaceutical formulations.

    Science.gov (United States)

    Felix, Fabiana S; Brett, Christopher M A; Angnes, Lúcio

    2007-04-11

    Flow injection analysis (FIA) with amperometric detection was employed for acetaminophen quantification in pharmaceutical formulations using a carbon film resistor electrode. This sensor exhibited sharp and reproducible current peaks for acetaminophen without chemical modification of its surface. A wide linear working range (8.0x10(-7) to 5.0x10(-4) mol L(-1)) in phosphate buffer solution as well as high sensitivity (0.143 A mol(-1) L cm(-2)) and low submicromolar detection limit (1.36x10(-7) mol L(-1)) were achieved. The repeatability (R.S.D. for 10 successive injections of 5.0x10(-6) and 5.0x10(-5) mol L(-1) acetaminophen solutions) was 3.1 and 1.3%, respectively, without any memory effect between injections. The new procedure was applied to the analyses of commercial pharmaceutical products and the results were in good agreement with those obtained utilizing a spectrophotometric method. Consequently, this amperometric method has been shown to be very suitable for quality control analyses and other applications with similar requirements.

  19. Transcorneal permeation of diclofenac as a function of temperature from film formulation in presence of triethanolamine and benzalkonium chloride.

    Science.gov (United States)

    Mohapatra, Rajaram; Senapati, Sibananda; Sahoo, Chinmaya; Mallick, Subrata

    2014-11-01

    The objective of this report was to evaluate the transcorneal permeation of diclofenac potassium (DCP) as a function of temperature from hydroxypropyl methylcellulose (HPMC) matrix film containing triethanolamine (TEM) as plasticizer and benzalkonium chloride (BKC) as preservative. Activation energy (Ea), enthalpy (ΔH), entropy (ΔS) and free energy (ΔG) of permeation, diffusion and partition were evaluated to understand the underlying mechanism of permeation. Permeation improved with the presence of both the plasticizer and preservative compared to preservative alone. Further, increased amount of TEM in the film increased drug transport across the cornea. Decreased Ea value of the film supported the fact. Rise of temperature from 26 to 30, 34 and 40 °C increased permeation in all the films. Ocular residence of the film in vivo in the rabbit revealed that the film swelled by pronounced lachrymal fluid uptake and traces of hydrogel remained still at the end of 6 h of application. Absence of characteristic exothermic peak of the drug in the thermogram of film formulations indicated the molecular dispersion of drug in polymer matrix. Scanning electron microscopy indicated that the drug crystal size decreased with increasing concentration of TEM in presence of BKC due to effective wetting of drug particles by the polymer. Copyright © 2014 Elsevier B.V. All rights reserved.

  20. Optical Degradation of Colloidal Eu-Complex Embedded in Silica Glass Film Using Reprecipitation and Sol-Gel Methods.

    Science.gov (United States)

    Fukuda, Takeshi; Kurabayashi, Tomokazu; Yamaki, Tatsuki

    2016-04-01

    A reprecipitation method has been investigated for fabricating colloidal nanoparticles using Eu-complex. Herein, we investigated optical degradation characteristics of (1,10-phenanthroline)tris [4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionato]europium(III) colloidal nanoparticles, which were embedded into a silica glass film fabricated by a conventional sol-gel process. At first, we tried several types of good solvents for the reprecipitation method, and dimethyl sulfoxide (DMSO) is found to be a suitable solvent for realizing the small diameter and the high long-term stability against the ultraviolet irradiation even though the boing point of DMSO is higher than that of water used as a poor solvent. By optimizing the good solvent and the concentration of Eu-complex, the relative photoluminescence intensity of 0.96 was achieved even though the ultraviolet light was continuously irradiated for 90 min. In addition, the average diameter of 106 nm was achieved when DMSO was used as a good solvent, resulting in the high transmittance at a visible wavelength region. Therefore, we can achieve the transparent emissive thin film with a center wavelength of 612 nm, and the optical degradation was drastically reduced by forming nanoparticles.

  1. Synthesis and electrical characterization of low-temperature thermal-cured epoxy resin/functionalized silica hybrid-thin films for application as gate dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Na, Moonkyong, E-mail: nmk@keri.re.kr [HVDC Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of); System on Chip Chemical Process Research Center, Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, 790-784 (Korea, Republic of); Kang, Young Taec [Creative and Fundamental Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of); Department of Polymer Science and Engineering, Pusan National University, Busan, 609-735 (Korea, Republic of); Kim, Sang Cheol [HVDC Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of); Kim, Eun Dong [Creative and Fundamental Research Division, Korea Electrotechnology Research Institute, Changwon, 642-120 (Korea, Republic of)

    2013-07-31

    Thermal-cured hybrid materials were synthesized from homogenous hybrid sols of epoxy resins and organoalkoxysilane-functionalized silica. The chemical structures of raw materials and obtained hybrid materials were characterized using Fourier transform infrared spectroscopy. The thermal resistance of the hybrids was enhanced by hybridization. The interaction between epoxy matrix and the silica particles, which caused hydrogen bonding and van der Waals force was strengthened by organoalkoxysilane. The degradation temperature of the hybrids was improved by approximately 30 °C over that of the parent epoxy material. The hybrid materials were formed into uniformly coated thin films of about 50 nm-thick using a spin coater. An optimum mixing ratio was used to form smooth-surfaced hybrid films. The electrical property of the hybrid film was characterized, and the leakage current was found to be well below 10{sup −6} A cm{sup −2}. - Highlights: • Preparation of thermal-curable hybrid materials using epoxy resin and silica. • The thermal stability was enhanced through hybridization. • The insulation property of hybrid film was investigated as gate dielectrics.

  2. Zwitterionic, cationic, and anionic fluorinated chemicals in aqueous film forming foam formulations and groundwater from U.S. military bases by nonaqueous large-volume injection HPLC-MS/MS.

    Science.gov (United States)

    Backe, Will J; Day, Thomas C; Field, Jennifer A

    2013-05-21

    A new analytical method was developed to quantify 26 newly-identified and 21 legacy (e.g. perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and fluorotelomer sulfonates) per and polyfluorinated alkyl substances (PFAS) in groundwater and aqueous film forming foam (AFFF) formulations. Prior to analysis, AFFF formulations were diluted into methanol and PFAS in groundwater were micro liquid-liquid extracted. Methanolic dilutions of AFFF formulations and groundwater extracts were analyzed by large-volume injection (900 μL) high-performance liquid chromatography tandem mass spectrometry. Orthogonal chromatography was performed using cation exchange (silica) and anion exchange (propylamine) guard columns connected in series to a reverse-phase (C18) analytical column. Method detection limits for PFAS in groundwater ranged from 0.71 ng/L to 67 ng/L, and whole-method accuracy ranged from 96% to 106% for analytes for which matched authentic analytical standards were available. For analytes without authentic analytical standards, whole-method accuracy ranged from 78 % to 144 %, and whole-method precision was less than 15 % relative standard deviation for all analytes. A demonstration of the method on groundwater samples from five military bases revealed eight of the 26 newly-identified PFAS present at concentrations up to 6900 ng/L. The newly-identified PFAS represent a minor fraction of the fluorinated chemicals in groundwater relative to legacy PFAS. The profiles of PFAS in groundwater differ from those found in fluorotelomer- and electrofluorination-based AFFF formulations, which potentially indicates environmental transformation of PFAS.

  3. Ce+3-and Tb+3-luminescence in glasses. Ce+3-activated bulk silica and silica thin films. An α-particle detector based on a Ce+3-activated silica thin film. A Ce+3-Tb+3-energy transfer in a high melting point phosphate glass

    International Nuclear Information System (INIS)

    Heindl, R.; Loriers, J.; Sella, J.C.; Robert, A.

    1984-07-01

    While many Ce +3 -activated glasses of different type emit strongly under UV (253,7 nm) and β-ray excitation, only the commercial silicate glass NE 905 shows an useful emission when exposed to α-particles. Only phosphate glasses have give the green Tb +3 -emission, when doped by it, under UV and α and β radiation. Sputtered films of Ce +3 -activated silica have appropriate luminescence properties, adherence to the substrate and a perfect chemical resistance to hot nitric acid. An α-particle detector has been built which has permitted the quantitative detection of plutonium in the presence of other radiative ions

  4. A facile and efficient method of enzyme immobilization on silica particles via Michael acceptor film coatings: immobilized catalase in a plug flow reactor.

    Science.gov (United States)

    Bayramoglu, Gulay; Arica, M Yakup; Genc, Aysenur; Ozalp, V Cengiz; Ince, Ahmet; Bicak, Niyazi

    2016-06-01

    A novel method was developed for facile immobilization of enzymes on silica surfaces. Herein, we describe a single-step strategy for generating of reactive double bonds capable of Michael addition on the surfaces of silica particles. This method was based on reactive thin film generation on the surfaces by heating of impregnated self-curable polymer, alpha-morpholine substituted poly(vinyl methyl ketone) p(VMK). The generated double bonds were demonstrated to be an efficient way for rapid incorporation of enzymes via Michael addition. Catalase was used as model enzyme in order to test the effect of immobilization methodology by the reactive film surface through Michael addition reaction. Finally, a plug flow type immobilized enzyme reactor was employed to estimate decomposition rate of hydrogen peroxide. The highly stable enzyme reactor could operate continuously for 120 h at 30 °C with only a loss of about 36 % of its initial activity.

  5. Pharmacokinetics and bioavailability study of two ondansetron oral soluble film formulations in fasting healthy male Chinese volunteers

    Directory of Open Access Journals (Sweden)

    Zhu YB

    2015-08-01

    Full Text Available Yubing Zhu,1 Qian Zhang,1 Jianjun Zou,2 Meng Wan,1 Zheng Zhao,1 Junrong Zhu1 1Department of Pharmacy, 2Laboratory of Clinical Pharmacology, Nanjing First Hospital, Nanjing Medical University, Nanjing, Jiangsu, People’s Republic of China Background: Ondansetron oral soluble film is designed to be applied on top of the tongue without requiring water to aid dissolution or swallowing, which is especially fitting for nausea and vomiting patients.Purpose: This study was conducted to compare the bioavailability of two 8 mg ondansetron oral soluble film formulations.Patients and methods: This randomized, open-label, two-period crossover study was performed under fasting conditions. A total of ten eligible subjects were randomly assigned at a 1:1 ratio to receive a single 8 mg dose of the test and reference ondansetron oral soluble film formulations, followed by a 1-week washout period and administration of the alternate formulation. The concentrations of ondansetron were assayed using an liquid chromatograph-mass spectrometer/mass spectrometer (LC-MS/MS method. For analysis of pharmacokinetic properties, including the peak concentration of Tmax (Cmax, AUC from time 0 (baseline to t hours (AUC0–t, and AUC from baseline to infinity (AUC0–∞, blood samples were obtained at intervals over the 24-hour period after studying drug administration. Tolerability was assessed by monitoring vital signs and laboratory tests (hematology, blood biochemistry, hepatic function, and urinalysis and by questioning subjects about adverse events.Results: The mean (standard derivation [SD] relative bioavailability was 96.5 (23.7%. The 90% confidence intervals (CIs for the log-transformed ratios of Cmax and AUC0–t were 84.71%–103.28% and 91.38%–108.60%, respectively (P>0.05. Similar results were found for the data without log-transformation. No statistically significant differences were found based on analysis of variance. No significant adverse events occurred

  6. Diffusion structural analysis study of titania films deposited by sol-gel technique on silica glass

    Czech Academy of Sciences Publication Activity Database

    Balek, V.; Mitsuhashi, T.; Bountseva, I.M.; Haneda, H.; Málek, Z.; Šubrt, Jan

    2003-01-01

    Roč. 26, 1-3 (2003), s. 185-189 ISSN 0928-0707. [International Workshop on Glasses, Ceramics, Hybrids and Nanocomposites from Gels /11./. Abano Terme, 16.09.2001-21.09.2001] Institutional research plan: CEZ:AV0Z4032918 Keywords : titania film * diffusion structural analysis * sol-gel Subject RIV: CA - Inorganic Chemistry Impact factor: 1.546, year: 2003

  7. Photoluminescence of Se-related oxygen deficient center in ion-implanted silica films

    International Nuclear Information System (INIS)

    Zatsepin, A.F.; Buntov, E.A.; Pustovarov, V.A.; Fitting, H.-J.

    2013-01-01

    The results of low-temperature time-resolved photoluminescence (PL) investigation of thin SiO 2 films implanted with Se + ions are presented. The films demonstrate an intensive PL band in the violet spectral region, which is attributed to the triplet luminescence of a new variant of selenium-related oxygen deficient center (ODC). The main peculiarity of the defect energy structure is the inefficient direct optical excitation. Comparison with spectral characteristics of isoelectronic Si-, Ge- and SnODCs show that the difference in electronic properties of the new center is related to ion size factor. It was established that the dominating triplet PL excitation under VUV light irradiation is related to the energy transfer from SiO 2 excitons. A possible model of Se-related ODC is considered. -- Highlights: • The low-temperature photoluminescence of thin SiO 2 films implanted with Se + ions was studied. • The 3.4 eV PL band was attributed to triplet luminescence of Se-related ODC. • The peculiarity of SeODC electronic properties is related to ion size factor. • The dominating VUV excitation of triplet PL is related to energy transfer from SiO 2 excitons. • A possible model of Se-related ODC is considered

  8. Molecular Structure and Dynamics in Thin Water Films at the Silica and Graphite Surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Argyris, Dr. Dimitrios [University of Oklahoma; Tummala, Dr. Naga Rajesh [University of Oklahoma; StrioloDr., A [Vanderbilt University; Cole, David R [ORNL

    2008-01-01

    The structure and dynamic properties of interfacial water at the graphite and silica solid surfaces were investigated using molecular dynamics simulations. The effect of surface properties on the characteristics of interfacial water was quantified by computing density profiles, radial distribution functions, surface density distributions, orientation order parameters, and residence and reorientation correlation functions. In brief, our results show that the surface roughness, chemical heterogeneity, and surface heterogeneous charge distribution affect the structural and dynamic properties of the interfacial water molecules, as well as their rate of exchange with bulk water. Most importantly, our results indicate the formation of two distinct water layers at the SiO2 surface covered by a large density of hydroxyl groups. Further analysis of the data suggests a highly confined first layer where the water molecules assume preferential hydrogen-down orientation and a second layer whose behavior and characteristics are highly dependent on those of the first layer through a well-organized hydrogen bond network. The results suggest that water-water interactions, in particular hydrogen bonds, may be largely responsible for macroscopic interfacial properties such as adsorption and contact angle.

  9. Oral fast-dissolving films containing lutein nanocrystals for improved bioavailability: formulation development, in vitro and in vivo evaluation.

    Science.gov (United States)

    Liu, Chen; Chang, Daoxiao; Zhang, Xinhui; Sui, Hong; Kong, Yindi; Zhu, Rongyue; Wang, Wenping

    2017-11-01

    Lutein is widely used as diet supplement for prevention of age-related macular degeneration. However, the application and efficacy of lutein in food and nutritional products has been hampered due to its poor solubility and low oral bioavailability. This study aimed to develop and evaluate the formulation of oral fast-dissolving film (OFDF) containing lutein nanocrystals for enhanced bioavailability and compliance. Lutein nanocrystals were prepared by anti-solvent precipitation method and then encapsulated into the films by solvent casting method. The formulation of OFDF was optimized by Box-Behnken Design (BBD) as follows: HPMC 2.05% (w/v), PEG 400 1.03% (w/v), Cremophor EL 0.43% (w/v). The obtained films exhibited uniform thickness of 35.64 ± 1.64 μm and drug content of 0.230 ± 0.003 mg/cm 2 and disintegrated rapidly in 29 ± 8 s. The nanocrystal-loaded films with reconstituted particle size of 377.9 nm showed better folding endurance and faster release rate in vitro than the conventional OFDFs with raw lutein. The microscope images, thermograms, and diffractograms indicated that lutein nanocrystals were highly dispersed into the films. After administrated to SD rats, t max was decreased from 3 h for oral solution formulation to less than 0.8 h for OFDF formulations, and C max increased from 150 ng/mL for solution to 350 ng/mL for conventional OFDF or 830 ng/mL for nanocrystal OFDF. The AUC 0-24h of conventional or nanocrystal OFDF was 1.37 or 2.08-fold higher than that of the oral solution, respectively. These results suggested that drug nanocrystal-loaded OFDF can be applied as a promising approach for enhanced bioavailability of poor soluble drugs like lutein.

  10. Metal Oxide Thin Films Grafted on Silica Gel Surfaces: Recent Advances on the Analytical Application of these Materials

    Directory of Open Access Journals (Sweden)

    Gushikem Yoshitaka

    2001-01-01

    Full Text Available In the highly dispersed MxOy monolayer film on a porous SiO2 surface, denoted as SiO2/MxOy, the Si-O-M covalent bond formed on the SiO2 surface restricts the mobility of the attached oxide resulting in coordinatively unsaturated metal oxides (LAS in addition to the Brønsted acid sites (BAS. The BAS arise from the MOH and SiOH groups, the latter due to the unreacted silanol groups. As the attached oxides are strongly immobilized on the surface, they are also thermally very stable. The amphoteric character of most of the attached oxides allows the immobilization of various chemical species, acid or bases, resulting in a wide application of these surface modified materials. In this work many of the recent applications of these MxOy coated silica surfaces are described, such as selective adsorbents, in preconcentration processes, as new packing material for use in HPLC, support for immobilization of enzymes, amperometric electrodes, sensors and biosensors

  11. The effect of formulation additives on the properties of films prepared ...

    African Journals Online (AJOL)

    Method: Films were prepared by solvent casting method using Terminalia, xanthan gums and hydroxylpropy lmethylcellulose (HPMC). Terminlia was also combined with xanthan, HPMC at different ratios using propylene glycol and glycerol as plaasticizers. The films were characterized using adherence, folding endurance ...

  12. Fabrication of transparent superhydrophobic silica-based film on a glass substrate

    Science.gov (United States)

    Wang, Shing-Dar; Luo, Shih-Shiang

    2012-05-01

    Tetraethoxysilane (TEOS) was hydrolyzed in an acidic environment and then reacted with hexamethyldisilazane (HMDS) to obtain a superhydrophobic transparent film on a glass substrate. The molar ratios of water and ethanol to TEOS, the pH value of the acidic (or basic) water that is used to hydrolyze TEOS, the heat treatment conditions and other factors were investigated systematically to optimize the transmission through, and the contact angle of water on the film. HMDS (total amount of HMDS/TEOS = 2) was divided into 20 parts, which were added into the sol successively to prevent the sudden production of a large quantity of NH3 in a small area of the sol. The optical and hydrophobic properties of the sol gel continued to change after it had been prepared. The conditions that TEOS was hydrolyzed with acidic water at pH 1.2 at 70 °C and the sol gel was aged at 20 °C for 48 h realized transmission of 90.9% and a water contact angle of 154.3°. No additional surface chemistry modification was needed.

  13. Nanoencapsulation of Rose-Hip Oil Prevents Oil Oxidation and Allows Obtainment of Gel and Film Topical Formulations.

    Science.gov (United States)

    Contri, Renata V; Kulkamp-Guerreiro, Irene C; da Silva, Sheila Janine; Frank, Luiza A; Pohlmann, Adriana R; Guterres, Silvia S

    2016-08-01

    The rose-hip oil holds skin regenerating properties with applications in the dermatological and cosmetic area. Its nanoencapsulation might favor the oil stability and its incorporation into hydrophilic formulations, besides increasing the contact with the skin and prolonging its effect. The aim of the present investigation was to develop suitable rose-hip-oil-loaded nanocapsules, to verify the nanocapsule effect on the UV-induced oxidation of the oil and to obtain topical formulations by the incorporation of the nanocapsules into chitosan gel and film. The rose-hip oil (500 or 600 μL), polymer (Eudragit RS100®, 100 or 200 mg), and acetone (50 or 100 mL) contents were separately varied aiming to obtain an adequate size distribution. The results led to a combination of the factors acetone and oil. The developed formulation showed average diameter of 158 ± 6 nm with low polydispersity, pH of 5.8 ± 0.9, zeta potential of +9.8 ± 1.5 mV, rose-hip oil content of 54 ± 1 μL/mL and tendency to reversible creaming. No differences were observed in the nanocapsules properties after storage. The nanoencapsulation of rose-hip oil decreased the UVA and UVC oxidation of the oil. The chitosan gel and film containing rose-hip-oil-loaded nanocapsules showed suitable properties for cutaneous use. In conclusion, it was possible to successfully obtain rose-hip-oil-loaded nanocapsules and to confirm the nanocapsules effect in protecting the oil from the UV rays. The chitosan gel and film were considered interesting alternatives for incorporating the nanoencapsulated rose-hip oil, combining the advantages of the nanoparticles to the advantages of chitosan.

  14. Formulation and In Vitro Characterization of Thiolated Buccoadhesive Film of Fluconazole.

    Science.gov (United States)

    Naz, Kiran; Shahnaz, Gul; Ahmed, Naveed; Qureshi, Naveeda Akhtar; Sarwar, Hafiz Shoaib; Imran, Muhammad; Khan, Gul Majid

    2017-05-01

    The present work is focused on the development of thiolated film for fluconazole buccal delivery. To this end, unmodified polymers chitosan and sodium carboxymethylcellulose (NaCMC) backbone was covalently modified by thioglycolic acid (TGA) and cysteine, respectively. The thiolated buccoadhesive film was evaluated in terms of thickness, weight uniformity, water-uptake capacity, drug content, and release patterns. Moreover, mucoadhesion profile was investigated on buccal mucosa. The resulting chitosan-TGA and NaCMC-cysteine conjugates displayed 171 ± 13 and 380 ± 19 μmol thiol groups per gram of polymer (mean ± SD; n = 3), respectively. The water binding capacity of the thiolated film was significantly ∼2-fold higher (p thiolated film displayed 5.8-fold higher mucoadhesive properties compared with corresponding film. Controlled release of drugs from film was observed over 8 h. The transport of fluconazole across excised buccal mucosa was enhanced up to 17-fold in comparison with fluconazole applied in buffer. Based on these findings, thiolated film seems to be promising for fluconazole buccal delivery.

  15. Formulation of Novel Layered Sodium Carboxymethylcellulose Film Wound Dressings with Ibuprofen for Alleviating Wound Pain

    Directory of Open Access Journals (Sweden)

    Lenka Vinklárková

    2015-01-01

    Full Text Available Effective assessment and management of wound pain can facilitate both improvements in healing rates and overall quality of life. From a pharmacological perspective, topical application of nonsteroidal anti-inflammatory drugs in the form of film wound dressings may be a good choice. Thus, the aim of this work was to develop novel layered film wound dressings containing ibuprofen based on partially substituted fibrous sodium carboxymethylcellulose (nonwoven textile Hcel NaT. To this end, an innovative solvent casting method using a sequential coating technique has been applied. The concentration of ibuprofen which was incorporated as an acetone solution or as a suspension in a sodium carboxymethylcellulose dispersion was 0.5 mg/cm2 and 1.0 mg/cm2 of film. Results showed that developed films had adequate mechanical and swelling properties and an advantageous acidic surface pH for wound application. An in vitro drug release study implied that layered films retained the drug for a longer period of time and thus could minimize the frequency of changing the dressing. Films with suspended ibuprofen demonstrated higher drug content uniformity and superior in vitro drug release characteristics in comparison with ibuprofen incorporation as an acetone solution. Prepared films could be potential wound dressings for the effective treatment of wound pain in low exuding wounds.

  16. Formulation and Characterization of Cu Doped ZnO Thick Films as LPG Gas Sensor

    Directory of Open Access Journals (Sweden)

    A. V. PATIL

    2010-12-01

    Full Text Available Thick films of pure and various concentrations (1 wt. %, 3 wt. %, 5 wt. %, 7 wt. % and 10 wt. % of Cu-doped ZnO were prepared on alumina substrates using a screen printing technique. These films were fired at a temperature of 700ºC for two hours in an air atmosphere. Morphological, compositional and structural properties of the samples were obtained using the scanning electron microscopy (SEM, Energy dispersive spectroscopy (EDAX and X-ray diffraction techniques respectively. The LPG gas sensing properties of these thick films were investigated at different operating temperatures and LPG gas concentrations. The surface resistance of thick films decreases when exposed to LPG gas. The Cu doped films show significant sensitivity to LPG gas than pure ZnO film. 5 wt. % Cu-doped ZnO film was found to be more sensitive (87.3 % to LPG gas exposed at 300 oC than other doping concentrations with fast response and recovery time.

  17. Formulation of Novel Layered Sodium Carboxymethylcellulose Film Wound Dressings with Ibuprofen for Alleviating Wound Pain

    Science.gov (United States)

    Vinklárková, Lenka; Vetchý, David; Bernatonienė, Jurga

    2015-01-01

    Effective assessment and management of wound pain can facilitate both improvements in healing rates and overall quality of life. From a pharmacological perspective, topical application of nonsteroidal anti-inflammatory drugs in the form of film wound dressings may be a good choice. Thus, the aim of this work was to develop novel layered film wound dressings containing ibuprofen based on partially substituted fibrous sodium carboxymethylcellulose (nonwoven textile Hcel NaT). To this end, an innovative solvent casting method using a sequential coating technique has been applied. The concentration of ibuprofen which was incorporated as an acetone solution or as a suspension in a sodium carboxymethylcellulose dispersion was 0.5 mg/cm2 and 1.0 mg/cm2 of film. Results showed that developed films had adequate mechanical and swelling properties and an advantageous acidic surface pH for wound application. An in vitro drug release study implied that layered films retained the drug for a longer period of time and thus could minimize the frequency of changing the dressing. Films with suspended ibuprofen demonstrated higher drug content uniformity and superior in vitro drug release characteristics in comparison with ibuprofen incorporation as an acetone solution. Prepared films could be potential wound dressings for the effective treatment of wound pain in low exuding wounds. PMID:26090454

  18. Novel Nano-Liposome Formulation for Dry Eyes with Components Similar to the Preocular Tear Film

    Directory of Open Access Journals (Sweden)

    Marta Vicario-de-la-Torre

    2018-04-01

    Full Text Available Dry eye is commonly treated with artificial tears; however, developing artificial tears similar to natural tears is difficult due to the complex nature of tears. We characterized and evaluated a novel artificial tear formulation with components similar to the lipid and aqueous constituents of natural tears. Nano-liposomes, composed in part of phosphatidylcholine, were dispersed in an aqueous solution of bioadhesive sodium hyaluronate. Liposome size, zeta potential, and physicochemical properties of the fresh and stored (4 °C liposomal formulation were analyzed. In vitro tolerance was tested using human corneal and conjunctival cell lines by exposures of 15 min to 4 h. The tolerance of the liposomal formulation was evaluated in animals (rabbits. The average liposome size was 186.3 ± 7.0 nm, and the zeta potential was negative. The osmolarity of the formulation was 198.6 ± 1.7 mOsm, with a surface tension of 36.5 ± 0.4 mN/m and viscosity of 3.05 ± 0.02 mPa·s. Viability values in the human corneal and conjunctival cell lines were always >80%, even after liposomal formulation storage for 8 weeks. Discomfort and clinical signs after instillation in rabbit eyes were absent. The new formulation, based on phosphatidylcholine-liposomes dispersed in sodium hyaluronate has suitable components and characteristics, including high in vitro cell viability and good in vivo tolerance, to serve as a tear substitute.

  19. Effect of nano silica based modifying agent for hydrophobic coating application

    International Nuclear Information System (INIS)

    Nurul Huda Mudri; Nik Ghazali Nik Salleh; Mek Zah Salleh

    2016-01-01

    Hydrophobic coatings find wide application in industry due to their unique features such as water repellent and self-cleaning properties. In this study, modifying agent was synthesized by way of nano silica particles dispersion in polydimethyl siloxane with addition of surfactant, catalyst and stabilizer using high speed distemper. The modifying agent was added into coating formulation and cured under UV exposure. Scanning Electron Microscopy image of the film found that the nano silica particles were distributed well on substrate. Contact angle measurement gave the highest reading of 116 degree for 20 % wt of the modifying agent. The optical properties of the film were evaluated via transmission and haze test. (author)

  20. Magnetic and in vitro heating properties of implants formed in situ from injectable formulations and containing superparamagnetic iron oxide nanoparticles (SPIONs) embedded in silica microparticles for magnetically induced local hyperthermia

    International Nuclear Information System (INIS)

    Le Renard, Pol-Edern; Lortz, Rolf; Senatore, Carmine; Rapin, Jean-Philippe; Buchegger, Franz; Petri-Fink, Alke; Hofmann, Heinrich; Doelker, Eric; Jordan, Olivier

    2011-01-01

    The biological and therapeutic responses to hyperthermia, when it is envisaged as an anti-tumor treatment modality, are complex and variable. Heat delivery plays a critical role and is counteracted by more or less efficient body cooling, which is largely mediated by blood flow. In the case of magnetically mediated modality, the delivery of the magnetic particles, most often superparamagnetic iron oxide nanoparticles (SPIONs), is also critically involved. We focus here on the magnetic characterization of two injectable formulations able to gel in situ and entrap silica microparticles embedding SPIONs. These formulations have previously shown suitable syringeability and intratumoral distribution in vivo. The first formulation is based on alginate, and the second on a poly(ethylene-co-vinyl alcohol) (EVAL). Here we investigated the magnetic properties and heating capacities in an alternating magnetic field (141 kHz, 12 mT) for implants with increasing concentrations of magnetic microparticles. We found that the magnetic properties of the magnetic microparticles were preserved using the formulation and in the wet implant at 37 o C, as in vivo. Using two orthogonal methods, a common SLP (20 W g -1 ) was found after weighting by magnetic microparticle fraction, suggesting that both formulations are able to properly carry the magnetic microparticles in situ while preserving their magnetic properties and heating capacities. - Research highlights: → Magnetic formulations that form implants on injection into tissues are proposed for hyperthermia. → Superparamagnetic properties of the SPION-silica composite microparticles are preserved in the wet implants. → Heat-dissipating properties (SLP of 20 W/g of implant) support in vivo use.

  1. Influence of different formulations and granulation techniques on dissolution of folic acid in film coated tablets

    Directory of Open Access Journals (Sweden)

    Ljiljana Krsteska

    2011-07-01

    Full Text Available The vitamin folic acid has received considerable attention because of it′s role in decreasing risk of neural tube birth defects, and it′s potential role in reducing risks of cardiovascular and psychiatric diseases. We evaluated compositions of 5 different formulations in terms of meeting the USP standard for dissolution and disintegration .However all the examined formulations had met the disintegration test but only 3 formulations had met the dissolution requirements to release 75 % of the active ingredient in 45 minutes. The maximum value of dissolution of 97.52 % in S5 composition was achieved by combination of certain excipients (combination of hydrophilic and hydrophobic filler and suitable wetting agent and wet high shear mixing granulation technique, resulting with optimize release of the active substance.

  2. Orodispersible films in individualized pharmacotherapy : The development of a formulation for pharmacy preparations

    NARCIS (Netherlands)

    Visser, Caroline; Woerdenbag, Herman J.; Crediet, Stefan; Gerrits, Edwin; Lesschen, Marjan A.; Hinrichs, Wouter L.J.; Breitkreutz, Jörg; Frijlink, Henderik W.

    2015-01-01

    Orodispersible films (ODFs) are promising drug delivery systems for customized small scale pharmacy preparations. The aim of the present study was to develop a versatile casting solution suitable for the extemporaneous production of ODFs to which active pharmaceutical ingredients (APIs) can be

  3. Encapsulation of dye molecules into mesoporous polymer resin and mesoporous polymer-silica films by an evaporation-induced self-assembly method

    Energy Technology Data Exchange (ETDEWEB)

    Chi Yue; Li Nan; Tu Jinchun; Zhang Yujie [School of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, Changchun 130012 (China); Li Xiaotian, E-mail: xiaotianli@jlu.edu.c [School of Material Science and Engineering, Key Laboratory of Automobile Materials of Ministry of Education, Jilin University, Changchun 130012 (China); Shao Changlu, E-mail: clshao@nenu.edu.c [Center for Advanced Optoelectronic Functional Materials Research, Northeast Normal University, Changchun 130024 (China)

    2010-03-15

    Polymer resin and polymer-silica films with highly ordered mesostructure have been used as host materials to encapsulate DCM (4-(dicyanomethylene) -2-methyl-6-(4-dimethylaminostyryl)-4h-pyran), a kind of fluorescent dye, through evaporation-induced self-assembly method (EISA). After encapsulation, the composites show significant blue-shift in photoluminescence (PL) spectra. Particularly, by changing the excitation wavelength, the samples show different emission bands. These phenomena are related to the mesostructure and the positions of DCM molecules in the host.

  4. In situ crystallization of b-oriented MFI films on plane and curved substrates coated with a mesoporous silica layer

    KAUST Repository

    Deng, Zhiyong; Pera-Titus, Marc

    2013-01-01

    a silica source to promote the nucleation and growth of zeolite crystals via a heterogeneous nucleation mechanism (zeolitization), and adsorb zeolite moieties generated in the synthesis solution via a homogeneous nucleation mechanism. A monolayer

  5. Influences of surface charge, size, and concentration of colloidal nanoparticles on fabrication of self-organized porous silica in film and particle forms.

    Science.gov (United States)

    Nandiyanto, Asep Bayu Dani; Suhendi, Asep; Arutanti, Osi; Ogi, Takashi; Okuyama, Kikuo

    2013-05-28

    Studies on preparation of porous material have attracted tremendous attention because existence of pores can provide material with excellent performances. However, current preparation reports described successful production of porous material with only partial information on charges, interactions, sizes, and compositions of the template and host materials. In this report, influences of self-assembly parameters (i.e., surface charge, size, and concentration of colloidal nanoparticles) on self-organized porous material fabrication were investigated. Silica nanoparticles (as a host material) and polystyrene (PS) spheres (as a template) were combined to produce self-assembly porous materials in film and particle forms. The experimental results showed that the porous structure and pore size were controllable and strongly depended on the self-assembly parameters. Materials containing highly ordered pores were effectively created only when process parameters fall within appropriate conditions (i.e., PS surface charge ≤ -30 mV; silica-to-PS size ratio ≤0.078; and silica-to-PS mass ratio of about 0.50). The investigation of the self-assembly parameter landscape was also completed using geometric considerations. Because optimization of these parameters provides significant information in regard to practical uses, results of this report could be relevant to other functional properties.

  6. Formulation and Characterization of Fast-Dissolving Sublingual Film of Iloperidone Using Box-Behnken Design for Enhancement of Oral Bioavailability.

    Science.gov (United States)

    Londhe, Vaishali; Shirsat, Rucha

    2018-04-01

    Iloperidone is a second-generation antipsychotic drug which is used for the treatment of schizophrenia and has very low aqueous solubility and bioavailability. This drug also undergoes first-pass metabolism. The aim of this work is to formulate fast-dissolving sublingual films of iloperidone to improve its bioavailability. Sublingual films were prepared by solvent casting method. Hydroxypropyl methyl cellulose E5, propylene glycol 400, and transcutol HP were optimized using Box-Behnken three-level statistical design on the basis of disintegration time and folding endurance of films. Iloperidone:hydroxypropyl-β-cyclodextrin kneaded complex was used in films instead of plain drug due to its low solubility. Optimized film was further evaluated for drug content, pH, dissolution studies, ex vivo permeation studies, and pharmacokinetic studies in rats. The optimized film disintegrated within 30 s. The in vitro dissolution of the film showed 80.3 ± 3.4% drug dissolved within first 5 min. In ex vivo permeation studies using sublingual tissue, flux achieved within first 15 min by film was around 117.1 ± 0.35 (mcg/cm 2 /h) which was ten times more than that of plain drug. This formulation showed excellent uniformity. AUC and C max of film were significantly higher (p films was 148% when compared to the plain drug. Thus, this study showed optimized fast-dissolving sublingual film to improve permeation and bioavailability of iloperidone. Fast-dissolving films will be customer-friendly approach for geadiatric schizophrenic patients.

  7. Physiologically-based pharmacokinetic model of vaginally administered dapivirine ring and film formulations.

    Science.gov (United States)

    Kay, Katherine; Shah, Dhaval K; Rohan, Lisa; Bies, Robert

    2018-05-01

    A physiologically-based pharmacokinetic (PBPK) model of the vaginal space was developed with the aim of predicting concentrations in the vaginal and cervical space. These predictions can be used to optimize the probability of success of vaginally administered dapivirine (DPV) for HIV prevention. We focus on vaginal delivery using either a ring or film. A PBPK model describing the physiological structure of the vaginal tissue and fluid was defined mathematically and implemented in MATLAB. Literature reviews provided estimates for relevant physiological and physiochemical parameters. Drug concentration-time profiles were simulated in luminal fluids, vaginal tissue and plasma after administration of ring or film. Patient data were extracted from published clinical trials and used to test model predictions. The DPV ring simulations tested the two dosing regimens and predicted PK profiles and area under the curve of luminal fluids (29 079 and 33 067 mg h l -1 in groups A and B, respectively) and plasma (0.177 and 0.211 mg h l -1 ) closely matched those reported (within one standard deviation). While the DPV film study reported drug concentration at only one time point per patient, our simulated profiles pass through reported concentration range. HIV is a major public health issue and vaginal microbicides have the potential to provide a crucial, female-controlled option for protection. The PBPK model successfully simulated realistic representations of drug PK. It provides a reliable, inexpensive and accessible platform where potential effectiveness of new compounds and the robustness of treatment modalities for pre-exposure prophylaxis can be evaluated. © 2018 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.

  8. Fumed silica. Fumed silica

    Energy Technology Data Exchange (ETDEWEB)

    Sukawa, T.; Shirono, H. (Nippon Aerosil Co. Ltd., Tokyo (Japan))

    1991-10-18

    The fumed silica is explained in particulate superfineness, high purity, high dispersiveness and other remarkable characteristics, and wide application. The fumed silica, being presently produced, is 7 to 40nm in average primary particulate diameter and 50 to 380m{sup 2}/g in specific surface area. On the surface, there coexist hydrophilic silanol group (Si-OH) and hydrophobic siloxane group (Si-O-Si). There are many characteristics, mutually different between the fumed silica, made hydrophobic by the surface treatment, and untreated hydrophilic silica. The treated silica, if added to the liquid product, serves as agent to heighten the viscosity, prevent the sedimentation and disperse the particles. The highest effect is given to heighten the viscosity in a region of 4 to 9 in pH in water and alcohol. As filling agent to strengthen the elastomer and polymer, and powder product, it gives an effect to prevent the consolidation and improve the fluidity. As for its other applications, utilization is made of particulate superfineness, high purity, thermal insulation properties and adsorption characteristics. 2 to 3 patents are published for it as raw material of quartz glass. 38 refs., 16 figs., 4 tabs.

  9. Bioequivalence of 2 Formulations of Sildenafil Oral Soluble Film 100 mg and Sildenafil Citrate (Viagra) 100 mg Oral Tablets in Healthy Male Volunteers.

    Science.gov (United States)

    Dadey, Eric

    Sildenafil citrate tablets (VIAGRA; Pfizer Inc) have been used since 1998 as an oral therapy for the treatment of erectile dysfunction. However, in some cases, patients may have difficulty in swallowing tablets, and the need to use water to aid in the oral administration of the tablets has the potential to interrupt the sexual encounter, reduce spontaneity, and therefore decrease the quality of the experience. Two oral soluble film (OSF) formulations of sildenafil were developed using MonoSol Rx's proprietary PharmFilm technology. Both films were formulated to dissolve rapidly on the tongue, thereby releasing the drug into the oral cavity, whereupon it is swallowed without the use of water. From a patient perspective, it is anticipated that the film formulations of sildenafil citrate will provide a more compliant and discreet dosage form. The purpose of this clinical study was to compare the bioequivalence of the 2 sildenafil OSF 100 mg formulations (MonoSol Rx, LLC) with the sildenafil citrate 100 mg tablets. The design was a single-dose, randomized, open-label, 3-period, 6-sequence, 3-treatment, single-center, crossover study conducted in 18 healthy, nonsmoking male volunteers under fasting conditions, with each treatment period separated by a 7-day washout period. Plasma sildenafil concentrations were measured predose and then periodically to 24 hours after dosing. The 90% confidence intervals for plasma sildenafil AUC0-t, AUC0-∞, and Cmax for both sildenafil OSF formulations as compared with sildenafil citrate tablets were all within the 80%-125% range, indicating bioequivalence of both film formulations to sildenafil citrate tablets. Overall, the demonstrated bioequivalence coupled with the performance advantages of an OSF dosage form (ie, rapid dissolution in the mouth, can be taken without water, and can be dosed discreetly) suggest that the sildenafil OSF may provide an attractive alternative to sildenafil citrate oral tablets.

  10. Physical and antibacterial properties of açaí edible films formulated with thyme essential oil and apple skin polyphenols.

    Science.gov (United States)

    Espitia, Paula J P; Avena-Bustillos, Roberto J; Du, Wen-Xian; Chiou, Bor-Sen; Williams, Tina G; Wood, Delilah; McHugh, Tara H; Soares, Nilda F F

    2014-05-01

    Thyme essential oil (TEO) and apple skin polyphenols (ASP) are natural compounds considered as generally recognized as safe by FDA, with biological effects against bacteria and fungi. This work aimed to evaluate physical and antimicrobial properties of açaí edible films formulated with TEO and ASP at 3% and 6% (w/w) individually or combined at 3% (w/w) each. Physical properties studied include mechanical resistance, water vapor permeability (WVP), color, and thermal resistance. Antimicrobial activity against Listeria monocytogenes was determined using the overlay diffusion test. Addition of ASP resulted in improved mechanical properties. TEO at 6% (w/w) resulted in increased elongation. ASP films had significant higher WVP than control film. ASP films were lighter and had more red color than other films. Incorporation of ASP resulted in improved film thermal stability, whereas TEO caused rapid thermal decomposition. Presence of clusters was observed on the surface of films. Addition of ASP resulted in a smoother surface, whereas addition of TEO led to the formation of crater-like pits on the film surface. Açaí edible film incorporated with 6% (w/w) TEO presented the highest antimicrobial activity. However, both antimicrobials are necessary in the açaí films in order to obtain edible films with suitable physical-mechanical properties. The results of the present study showed that TEO and ASP can be used to prepare açaí edible films with adequate physical-mechanical properties and antimicrobial activity for food applications by direct contact. Developed açaí edible films presented antimicrobial activity against L. monocytogenes and good physical-mechanical properties, showing the potential use of açaí edible films in food preservation. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

  11. Fabrication Flexible and Luminescent Nanofibrillated Cellulose Films with Modified SrAl2O4: Eu, Dy Phosphors via Nanoscale Silica and Aminosilane

    Directory of Open Access Journals (Sweden)

    Longfei Zhang

    2018-05-01

    Full Text Available Flexible 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO-oxidized nanofibrillated cellulose (ONFC films with long afterglow luminescence containing modified SrAl2O4: Eu2+, Dy3+ (SAOED phosphors were fabricated by a template method. Tetraethyl orthosilicate (TEOS and (3-aminopropyl trimethoxy-silane (APTMS were employed cooperatively to improve the water resistance and compatibility of the SAOED particles in the ONFC suspension. The structure and morphology after modification evidenced the formation of a superior SiO2 layer and coarse amino-compounds on the surface of the phosphors. Homogeneous dispersions containing ONFC and the modified phosphors were prepared and the interface of composite films containing the amino-modified particles showed a more closely packed structure and had less voids at the interface between the cellulose and luminescent particles than that of silica-modified phosphors. The emission spectra for luminescent films showed a slight blue shift (3.2 nm at around 512 nm. Such flexible films with good luminescence, thermal resistance, and mechanical properties can find applications in fields like luminous flexible equipment, night indication, and portable logo or labels.

  12. Patternable Poly(chloro-p-xylylene Film with Tunable Surface Wettability Prepared by Temperature and Humidity Treatment on a Polydimethylsiloxane/Silica Coating

    Directory of Open Access Journals (Sweden)

    Yonglian Yu

    2018-03-01

    Full Text Available Poly(chloro-p-xylylene (PPXC film has a water contact angle (WCA of only about 84°. It is necessary to improve its hydrophobicity to prevent liquid water droplets from corroding or electrically shorting metallic circuits of semiconductor devices, sensors, microelectronics, and so on. Herein, we reported a facile approach to improve its surface hydrophobicity by varying surface pattern structures under different temperature and relative humidity (RH conditions on a thermal curable polydimethylsiloxane (PDMS and hydrophobic silica (SiO2 nanoparticle coating. Three distinct large-scale surface patterns were obtained mainly depending on the contents of SiO2 nanoparticles. The regularity of patterns was mainly controlled by the temperature and RH conditions. By changing the pattern structures, the surface wettability of PPXC film could be improved and its WCA was increased from 84° to 168°, displaying a superhydrophobic state. Meanwhile, it could be observed that water droplets on PPXC film with superhydrophobicity were transited from a “Wenzel” state to a “Cassie” state. The PPXC film with different surface patterns of 200 μm × 200 μm and the improved surface hydrophobicity showed wide application potentials in self-cleaning, electronic engineering, micro-contact printing, cell biology, and tissue engineering.

  13. Liquid Phase Deposition of Silica on the Hexagonally Close-Packed Monolayer of Silica Spheres

    Directory of Open Access Journals (Sweden)

    Seo Young Yoon

    2013-01-01

    Full Text Available Liquid phase deposition is a method used for the nonelectrochemical production of polycrystalline ceramic films at low temperatures, most commonly silicon dioxide films. Herein, we report that silica spheres are organized in a hexagonal close-packed array using a patterned substrate. On this monolayer of silica spheres, we could fabricate new nanostructures in which deposition and etching compete through a modified LPD reaction. In the early stage, silica spheres began to undergo etching, and then, silica bridges between the silica spheres appeared by the local deposition reaction. Finally, the silica spheres and bridges disappeared completely. We propose the mechanism for the formation of nanostructure.

  14. Effects of tablet formulation and subsequent film coating on the supersaturated dissolution behavior of amorphous solid dispersions.

    Science.gov (United States)

    Sakai, Toshiro; Hirai, Daiki; Kimura, Shin-Ichiro; Iwao, Yasunori; Itai, Shigeru

    2018-04-05

    The effects of tablet preparation and subsequent film coating with amorphous solid dispersion (ASD) particles that were composed of a drug with poor water solubility and hydrophilic polymers were investigated. ASD particles were prepared with a drug and vinylpyrrolidone-vinyl acetate copolymer (PVPVA) or polyvinylpyrrolidone (PVP) at a weight ratio of 1:1 or 1:2 using a melt extrusion technique. Tablets were prepared by conventional direct compression followed by pan coating. A mathematical model based on the Noyes-Whitney equation assuming that stable crystals precipitated at the changeable surface area of the solid-liquid interface used to estimate drug dissolution kinetics in a non-sink dissolution condition. All the ASD particles showed a maximum dissolution concentration approximately ten times higher than that of the crystalline drug. The ASD particles with PVPVA showed higher precipitation rate with lower polymer ratio, while PVP did not precipitate within 960 min regardless of the polymer ratio, suggesting the ASD particles of 1:1 drug:PVPVA (ASD-1) were the most unstable among the ASD particles considered. The dissolution of a core tablet with ASD-1 showed less supersaturation and a much higher precipitation rate than those of ASD-1 particles. However, a film-coated tablet or core tablet with a trace amount of hydroxypropylmethylcellulose (HPMC) showed a similar dissolution profile to that of the ASD-1 particles, indicating HPMC had a remarkable precipitation inhibition effect. Overall, these results suggest that tablet preparation with ASD may adversely affect the maintenance of supersaturation; however, this effect can be mitigated by adding an appropriate precipitation inhibitor to the formulation. Copyright © 2018 Elsevier B.V. All rights reserved.

  15. Assembly of crosslinked oxo-cyanoruthenate and zirconium oxide bilayers: Application in electrocatalytic films based on organically modified silica with templated pores

    International Nuclear Information System (INIS)

    Rutkowska, Iwona A.; Sek, Jakub P.; Mehdi, B. Layla; Kulesza, Pawel J.; Cox, James A.

    2014-01-01

    Electrochemical deposition of crosslinked oxo-cyanoruthenate, Ru-O/CN-O, from a mixture of RuCl 3 and K 4 Ru(CN) 6 is known to yield a film on glassy carbon that promotes oxidations by a combination of electron and oxygen transfer. Layer-by-layer (LbL) deposition of this species at a film formed by cycling of the electrode potential in a ZrO 2 solution systematically increases the number of catalytically active sites of the Ru-O/CN-O on the electrode. The evaluation of the electrocatalytic activity was by cyclic voltammetric oxidation of cysteine at pH 2. Plots of the anodic peak current vs. the square root of scan rate were indicative of linear diffusion control of this oxidation, even in the absence of ZrO 2 , but the slopes of these linear plots increased with bilayer number, n, of (ZrO 2 | Ru-O/CN-O) n . The latter observation is hypothesized to be due to an increased number of active sites for a given geometric electrode area, but proof requires further study. To optimize utilization of the catalyst and to provide a size-exclusion characteristic to the electrode, the study was extended to LbL deposition of the composite in 50-nm pores of an organically modified silica film deposited by electrochemically assisted sol-gel processing using surface-bound poly(styrene sulfonate) nanospheres as a templating agent

  16. Effect of Addition of Colloidal Silica to Films of Polyimide, Polyvinylpyridine, Polystyrene, and Polymethylmethacrylate Nano-Composites

    OpenAIRE

    Abdalla, Soliman; Al-Marzouki, Fahad; Obaid, Abdullah; Gamal, Salah

    2016-01-01

    Nano-composite films have been the subject of extensive work for developing the energy-storage efficiency of electrostatic capacitors. Factors such as polymer purity, nanoparticle size, and film morphology drastically affect the electrostatic efficiency of the dielectric material that forms the insulating film between the 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...

  17. On the formation mechanisms of the diffuse atmospheric pressure dielectric barrier discharge in CVD processes of thin silica-like films

    International Nuclear Information System (INIS)

    Starostin, S A; Premkumar, P Antony; Creatore, M; Van Veldhuizen, E M; Van de Sanden, M C M; De Vries, H; Paffen, R M J

    2009-01-01

    Pathways of formation and temporal evolution of the diffuse dielectric barrier discharge at atmospheric pressure were experimentally studied in this work by means of optical (fast imaging camera) and electrical diagnostics. The chosen model system is relevant for applications of plasma-enhanced chemical vapor deposition of thin silica-like film on the polymeric substrate, from cost-efficient gas mixtures of Ar/N 2 /O 2 /hexamethyldisiloxane. It was found that the discharge can gradually experience the phases of homogeneous low current Townsend-like mode, local Townsend to glow transition and expanding high current density (∼0.7 A cm -2 ) glow-like mode. While the glow-like current spot occupies momentarily only a small part of the electrode area, its expanding behavior provides uniform treatment of the whole substrate surface. Alternatively, it was observed that a visually uniform discharge can be formed by the numerous microdischarges overlapping over the large electrode area.

  18. The introduction of buprenorphine-naloxone film in opioid substitution therapy in Australia: Uptake and issues arising from changing buprenorphine formulations.

    Science.gov (United States)

    Larance, Briony; Dietze, Paul; Ali, Robert; Lintzeris, Nicholas; White, Nancy; Jenkinson, Rebecca; Degenhardt, Louisa

    2015-11-01

    Buprenorphine-naloxone (BNX) film for opioid dependence treatment was introduced in Australia in 2011. A key difference in State policy approaches saw transfer from BNX tablets to BNX film mandated in South Australia (SA) with New South Wales (NSW) and Victoria (VIC) having less stringent policies. This study examined (i) how initiations and transfers were implemented, (ii) the profile and predictors of adverse effects as self-reported by BNX film clients, and (iii) dosing issues. Survey of 334 buprenorphine (BPN), BNX tablet and BNX film clients and semi-structured interviews with 39 key experts (KEs) in 2012. Comparisons are made between clients interviewed in SA versus NSW and VIC combined. Among the 180 current BNX film clients, 23% started treatment on BNX film, 18% requested a transfer to BNX film and 59% (n = 106) reported their clinic/prescriber recommended transfer to BNX film. Among clients who were offered but refused a transfer to BNX film (n = 66), the most common reason was 'I am happy with my current treatment and do not see a reason to change' (53%). Some opioid substitution therapy clients and KE viewed transfers as 'forced' (i.e. no choice of buprenorphine formulation). Multivariable regression showed residing in SA (vs. NSW/VIC) and a shorter length of current treatment episode were associated with more BNX film-attributed adverse effects but clinic/prescriber-recommended transfer was not. The introduction of BNX film in Australia varied across States. A perception of restricted choice in medication may have undermined initial acceptance in SA. © 2015 Australasian Professional Society on Alcohol and other Drugs.

  19. Fabrication of Mesoporous Silica/Alumina Hybrid Membrane Film Nanocomposites using Template Sol-Gel Synthesis of Amphiphilic Triphenylene

    Science.gov (United States)

    Lintang, H. O.; Jalani, M. A.; Yuliati, L.; Salleh, M. M.

    2017-05-01

    Herein we reported that by introducing a one-dimensional (1D) substrate with a porous structure such as anodic aluminum oxide (AAO) membrane, mesoporous silica/alumina hybrid nanocomposites were successfully fabricated by using amphiphilic triphenylene (TPC10TEG) as a template in sol-gel synthesis (TPC10TEG/silicahex). For the optical study of the nanocomposites, TPC10TEG/silicahex showed absorption peak at 264 nm due to the ordered and long-range π-π stacking of the disc-like aromatic triphenylene core. Moreover, the hexagonal arrangement of TPC10TEG/silicahex was proven based on their diffraction peaks of d 100 and d 200 at 2θ = 2.52° and 5.04° and images of transmission electron microscopy (TEM), respectively. For fabrication of mesoporous silica/alumina hybrid membrane, TPC10TEG/silicahex was drop-casted onto AAO membrane for penetration into the porous structure via gravity. X-ray diffraction (XRD) analysis on the resulted hybrid nanocomposites showed that the diffraction peaks of d 100 and d 200 of TPC10TEG/silicahex were still preserved, indicating that the hexagonal arrangements of mesoporous silica were maintained even on AAO substrate. The morphology study on the hybrid nanocomposites using TEM, scanning electron microscope (SEM) and field emission scanning electron microscope (FE-SEM) showed the successful filling of most AAO channels with the TPC10TEG/silicahex nanocomposites.

  20. Evidence of coexistence of micro and nanoporosity of organo-silica polymeric films deposited on silicon by plasma deposition

    International Nuclear Information System (INIS)

    Purohit, Viswas; Mielczarski, Ela; Mielczarski, Jerzy A.; Akesso, Laurent

    2013-01-01

    A range of hybrid, SiOCH films were deposited on silicon substrates within a radio frequency plasma reactor using hexamethyldisiloxane (HMDSO) as a precursor. The plasma polymerized films were deposited at various HMDSO/argon/oxygen ratios. The composition and structure, at microscopic and nanoscopic levels, of the deposited films were determined by external reflection and transmission Fourier Transform Infrared (FTIR) spectroscopy as well as by X-Ray Photoelectron Spectroscopy (XPS). The content of carbon and oxygen in films were found to be inversely proportional to each other. XPS results showed that the outermost surface of the deposited films are nanoporous and coexist with microporosity which was revealed by electron microscopy. The structure of deposited coatings is anisotropic as was documented by polarized external reflection FTIR spectroscopy. Several correlations between the film chemical composition, surface structure, and macroscopic properties of the films such as: hydrophobicity and hydrophilicity were established. - Highlights: • Hybrid organo-polymer silicon films deposited by RF plasma on silicon substrates. • FTIR and XPS reveal porosity by interpreting bonding between Si and –O. • Quantification of nano and microporosity are identified with bonding of Si with –O

  1. Evidence of coexistence of micro and nanoporosity of organo-silica polymeric films deposited on silicon by plasma deposition

    Energy Technology Data Exchange (ETDEWEB)

    Purohit, Viswas, E-mail: vishwas.purohit@gmail.com [Laboratoire Environnment et Mineralurgie, UMR 7569 CNRS, INPL-ENSG, BP.40, 54501 Vandoeuvre-les-Nancy (France); Mielczarski, Ela; Mielczarski, Jerzy A. [Laboratoire Environnment et Mineralurgie, UMR 7569 CNRS, INPL-ENSG, BP.40, 54501 Vandoeuvre-les-Nancy (France); Akesso, Laurent [Teer Coatings Ltd., Droitwich, Worcestershire WR9 9AS (United Kingdom)

    2013-09-16

    A range of hybrid, SiOCH films were deposited on silicon substrates within a radio frequency plasma reactor using hexamethyldisiloxane (HMDSO) as a precursor. The plasma polymerized films were deposited at various HMDSO/argon/oxygen ratios. The composition and structure, at microscopic and nanoscopic levels, of the deposited films were determined by external reflection and transmission Fourier Transform Infrared (FTIR) spectroscopy as well as by X-Ray Photoelectron Spectroscopy (XPS). The content of carbon and oxygen in films were found to be inversely proportional to each other. XPS results showed that the outermost surface of the deposited films are nanoporous and coexist with microporosity which was revealed by electron microscopy. The structure of deposited coatings is anisotropic as was documented by polarized external reflection FTIR spectroscopy. Several correlations between the film chemical composition, surface structure, and macroscopic properties of the films such as: hydrophobicity and hydrophilicity were established. - Highlights: • Hybrid organo-polymer silicon films deposited by RF plasma on silicon substrates. • FTIR and XPS reveal porosity by interpreting bonding between Si and –O. • Quantification of nano and microporosity are identified with bonding of Si with –O.

  2. Formulation and in vitro and in vivo evaluation of film-coated montelukast sodium tablets using Opadry® yellow 20A82938 on an industrial scale

    Directory of Open Access Journals (Sweden)

    Zaid AN

    2013-02-01

    Full Text Available Abdel Naser Zaid,1 Salam Natur,2 Aiman Qaddumi,2 Abeer Abu Ghoush11Department of Pharmacy, Faculty of Medicine and Health Sciences, An-Najah National University, Nablus, Palestine; 2Pharmacare PLC, Ramallah, PalestinePurpose: The aim of this study was to formulate stable film-coated montelukast sodium (MS tablets using Opadry® yellow 20A82938 (Montikast® tablets and to evaluate their in vitro and in vivo release profile.Methods: MS core tablets were manufactured using a direct compression method. Opadry yellow 20A82938 aqueous coating dispersion was used as the film-coating material. Dissolution of the film-coated tablets was tested in 900 mL of 0.5% sodium lauryl sulfate solution and the bioequivalence of the tablets was tested by comparing them with a reference formulation – Singulair® tablets. In vitro–in vivo correlation was evaluated. The stability of the obtained film-coated tablets was evaluated according to International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use guidelines.Results: The efficiency of the film coating was determined by subjecting the coated tablets to gastric pH and drug release was analyzed using high-performance liquid chromatography. The coated tablets had no obvious defects. MS release met the study criterion of not less than 80% dissolved after 30 minutes in 0.5% sodium lauryl sulfate solution. Statistical comparison of the main pharmacokinetic parameters clearly indicated no significant difference between test and reference in any of the calculated pharmacokinetic parameters. Level A correlation between in vitro drug release and in vivo absorption was found to be satisfactory.Conclusion: These findings suggest that aqueous film coating with Opadry yellow 20A82938 is an easy, reproducible, and economical approach for preparing stable MS film-coated tablets without affecting the drug-release characteristics.Keywords: coating, stability, aqueous

  3. Nanostructured antistatic and antireflective thin films made of indium tin oxide and silica over-coat layer

    Science.gov (United States)

    Cho, Young-Sang; Hong, Jeong-Jin; Yang, Seung-Man; Choi, Chul-Jin

    2010-08-01

    Stable dispersion of colloidal indium tin oxide nanoparticles was prepared by using indium tin oxide nanopowder, organic solvent, and suitable dispersants through attrition process. Various comminution parameters during the attrition step were studied to optimize the process for the stable dispersion of indium tin oxide sol. The transparent and conductive films were fabricated on glass substrate using the indium tin oxide sol by spin coating process. To obtain antireflective function, partially hydrolyzed alkyl silicate was deposited as over-coat layer on the pre-fabricated indium tin oxide film by spin coating technique. This double-layered structure of the nanostructured film was characterized by measuring the surface resistance and reflectance spectrum in the visible wavelength region. The final film structure was enough to satisfy the TCO regulations for EMI shielding purposes.

  4. Mechanism of Solder Joint Cracks in Anisotropic Conductive Films Bonding and Solutions: Delaying Hot-Bar Lift-Up Time and Adding Silica Fillers

    Directory of Open Access Journals (Sweden)

    Shuye Zhang

    2018-01-01

    Full Text Available Micron sizes solder metallurgical joints have been applied in a thin film application of anisotropic conductive film and benefited three general advantages, such as lower joint resistance, higher power handling capability, and reliability, when compared with pressure based contact of metal conductor balls. Recently, flex-on-board interconnection has become more and more popular for mobile electronic applications. However, crack formation of the solder joint crack was occurred at low temperature curable acrylic polymer resins after bonding processes. In this study, the mechanism of SnBi58 solder joint crack at low temperature curable acrylic adhesive was investigated. In addition, SnBi58 solder joint cracks can be significantly removed by increasing the storage modulus of adhesives instead of coefficient of thermal expansion. The first approach of reducing the amount of polymer rebound can be achieved by using an ultrasonic bonding method to maintain a bonding pressure on the SnBi58 solder joints cooling to room temperature. The second approach is to increase storage modulus of adhesives by adding silica filler into acrylic polymer resins to prevent the solder joint from cracking. Finally, excellent acrylic based SnBi58 solder joints reliability were obtained after 1000 cycles thermal cycling test.

  5. A proton-exchange membrane prepared by the radiation grafting of styrene and silica into polytetrafluoroethylene films

    Science.gov (United States)

    Yu, Hongyan; Shi, Jianheng; Zeng, Xinmiao; Bao, Mao; Zhao, Xinqing

    2009-07-01

    A polytetrafluoroethylene (PTFE) based organic-inorganic hybrid proton-exchange membrane was prepared from simultaneous radiation grafting of styrene (St) into porous PTFE membrane with the in situ sol-gel reaction of tetraethoxysilane (TEOS) followed by sulfonation in fuming sulfonic acid. The effect of radiation on the sol-gel reaction was studied. The results show that radiation promotes the sol-gel reaction with the help of St at room temperature. Incorporated silica gel helps to produce higher degree of grafting (DOG). SEM analysis was conducted to confirm that the inorganic silicon oxide was introduced to produce hybrid membrane in this work. The proton conductivity of membrane evaluated using electrochemical impedance spectroscopy is much higher (14.3×10 -2 S cm -1) than that of Nafion ® 117 at temperature of 80 °C with acceptable water uptake 51 wt%.

  6. Formulation and Characterization of Cr2O3 Doped ZnO Thick Films as H2S Gas Sensor

    Directory of Open Access Journals (Sweden)

    A. V. PATIL

    2009-09-01

    Full Text Available Cr2O3 doped ZnO thick films have been prepared by screen printing technique and firing process. These films were characterized by X-ray diffraction (XRD, Scanning electron microscopy (SEM, and EDX. H2S gas sensing properties of these films were investigated at different operating temperatures and different H2S concentrations. The 7 wt. % Cr2O3 doped ZnO thick films exhibits excellent H2S gas sensing properties with maximum sensitivity of 99.12 % at 300 oC in air atmosphere with fast response and recovery time.

  7. Casein films: effects of formulation, environmental conditions, and addition of citric pectin on the structure and mechanical properties

    Science.gov (United States)

    Thin casein films for food packaging applications reportedly possess good strength and low oxygen permeability, but low water-resistance and elasticity. Modifying and customizing the mechanical properties of the films to target specific behaviors depending on environmental conditions would enable a...

  8. Silica sacrificial layer-assisted in-plane incorporation of Au nanoparticles into mesoporous titania thin films through different reduction methods.

    Science.gov (United States)

    Liang, Chih-Peng; Yamauchi, Yusuke; Liu, Chia-Hung; Wu, Kevin C-W

    2013-06-28

    This study focuses on the incorporation of gold nanoparticles (Au NPs) into our previously synthesized mesoporous titania thin films consisting of titania nanopillars and inverse mesospace (C. W. Wu, T. Ohsuna, M. Kuwabara and K. Kuroda, J. Am. Chem. Soc., 2006, 128, 4544-4545, denoted as MTTFs). Recently, mesoporous titania materials doped with noble metals such as gold have attracted considerable attention because noble metals can enhance the efficiency of mesoporous titania-based devices. In this research, we attempted to use four different reduction methods (i.e., thermal treatment, photo irradiation, liquid immersion, and vapor contacting) to introduce gold nanoparticles (Au NPs) into MTTFs. The synthesized Au@MTTFs were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). We further systematically investigated the formation mechanism of gold nanoparticles on the external and internal surfaces of the MTTFs. With the assistance of a silica sacrificial layer, well-dispersed Au NPs with sizes of 4.1 nm were obtained inside the MTTF by photo irradiation. The synthesized Au@MTTF materials show great potential in various photo-electronic and photo-catalytic applications.

  9. On the formation mechanisms of the diffuse atmospheric pressure dielectric barrier discharge in CVD processes of thin silica-like films

    Energy Technology Data Exchange (ETDEWEB)

    Starostin, S A; Premkumar, P Antony [Materials Innovation Institute (M2i), Mekelweg 2, 2600 GA Delft, The Netherland (Netherlands); Creatore, M; Van Veldhuizen, E M; Van de Sanden, M C M [Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); De Vries, H; Paffen, R M J [FUJIFILM Manufacturing Europe B.V, PO Box 90156, Tilburg (Netherlands)

    2009-11-15

    Pathways of formation and temporal evolution of the diffuse dielectric barrier discharge at atmospheric pressure were experimentally studied in this work by means of optical (fast imaging camera) and electrical diagnostics. The chosen model system is relevant for applications of plasma-enhanced chemical vapor deposition of thin silica-like film on the polymeric substrate, from cost-efficient gas mixtures of Ar/N{sub 2}/O{sub 2}/hexamethyldisiloxane. It was found that the discharge can gradually experience the phases of homogeneous low current Townsend-like mode, local Townsend to glow transition and expanding high current density ({approx}0.7 A cm{sup -2}) glow-like mode. While the glow-like current spot occupies momentarily only a small part of the electrode area, its expanding behavior provides uniform treatment of the whole substrate surface. Alternatively, it was observed that a visually uniform discharge can be formed by the numerous microdischarges overlapping over the large electrode area.

  10. Subnanopore filling during water vapor adsorption on microporous silica thin films as seen by low-energy positron annihilation

    Science.gov (United States)

    Ito, Kenji; Yoshimoto, Shigeru; O'Rourke, Brian E.; Oshima, Nagayasu; Kumagai, Kazuhiro

    2018-02-01

    Positron annihilation lifetime spectroscopy (PALS) using a low-energy positron microbeam extracted into air was applied to elucidating molecular-level pore structures formed in silicon-oxide-backboned microporous thin films under controlled humidity conditions; as a result, a direct observation of the interstitial spaces in the micropores filled with water molecules was achieved. It was demonstrated that PALS using a microbeam extracted into air in combination with water vapor adsorption is a powerful tool for the in-situ elucidation of both open and closed subnanoscaled pores of functional thin materials under practical conditions.

  11. Silica Nephropathy

    Directory of Open Access Journals (Sweden)

    N Ghahramani

    2010-06-01

    Full Text Available Occupational exposure to heavy metals, organic solvents and silica is associated with a variety of renal manifestations. Improved understanding of occupational renal disease provides insight into environmental renal disease, improving knowledge of disease pathogenesis. Silica (SiO2 is an abundant mineral found in sand, rock, and soil. Workers exposed to silica include sandblasters, miners, quarry workers, masons, ceramic workers and glass manufacturers. New cases of silicosis per year have been estimated in the US to be 3600–7300. Exposure to silica has been associated with tubulointerstitial disease, immune-mediated multisystem disease, chronic kidney disease and end-stage renal disease. A rare syndrome of painful, nodular skin lesions has been described in dialysis patients with excessive levels of silicon. Balkan endemic nephropathy is postulated to be due to chronic intoxication with drinking water polluted by silicates released during soil erosion. The mechanism of silica nephrotoxicity is thought to be through direct nephrotoxicity, as well as silica-induced autoimmune diseases such as scleroderma and systemic lupus erythematosus. The renal histopathology varies from focal to crescentic and necrotizing glomerulonephritis with aneurysm formation suggestive of polyarteritis nodosa. The treatment for silica nephrotoxicity is non-specific and depends on the mechanism and stage of the disease. It is quite clear that further research is needed, particularly to elucidate the pathogenesis of silica nephropathy. Considering the importance of diagnosing exposure-related renal disease at early stages, it is imperative to obtain a thorough occupational history in all patients with renal disease, with particular emphasis on exposure to silica, heavy metals, and solvents.

  12. Using non-feature films to teach diversity, cultural competence, and the DSM-IV-TR outline for cultural formulation.

    Science.gov (United States)

    Lim, Russell F; Diamond, Ronald J; Chang, Jacquelyn B; Primm, Annelle B; Lu, Francis G

    2008-01-01

    Feature films have been used for teaching in psychiatry for many years to demonstrate diagnoses, but the use of documentary and instructional films in resident and staff cultural competence training have not been extensively written about in the medical and psychological literature. This article will describe the films that have been used by the authors and suggest methods for their use in cultural competence and diversity training. A literature search was done using MEDLINE and PsychINFO and the authors were asked to describe their teaching methods. One article was found detailing the use of videotapes as a stimulus but not for cultural competence education, and two articles were found documenting the use of The Color of Fear as a stimulus for the discussion of racism. However, many educators use these films all across the country for the purpose of opening discussion about racism. Documentary, instructional, and public service announcements can be useful in teaching culturally competent assessment and treatment.

  13. Formulation and in vitro/in vivo evaluation of chitosan-based film forming gel containing ketoprofen.

    Science.gov (United States)

    Oh, Dong-Won; Kang, Ji-Hyun; Lee, Hyo-Jung; Han, Sang-Duk; Kang, Min-Hyung; Kwon, Yie-Hyuk; Jun, Joon-Ho; Kim, Dong-Wook; Rhee, Yun-Seok; Kim, Ju-Young; Park, Eun-Seok; Park, Chung-Woong

    2017-11-01

    The film forming gel, adhered to skin surfaces upon application and formed a film, has an advantage onto skin to provide protection and continuous drug release to the application site. This study aimed to prepare a chitosan-based film forming gel containing ketoprofen (CbFG) and to evaluate the CbFG and film from CbFG (CbFG-film). CbFG were prepared with chitosan, lactic acid and various skin permeation enhancers. The physicochemical characteristics were evaluated by texture analysis, viscometry, SEM, DSC, XRD and FT-IR. To identify the mechanism of skin permeation, in vitro skin permeation study was conducted with a Franz diffusion cell and excised SD-rat and hairless mouse dorsal skin. In vivo efficacy assessment in mono-iodoacetate (MIA)-induced rheumatoid arthritis animal model was also conducted. CbFG was successfully prepared and, after applying CbFG to the excised rat dorsal skin, the CbFG-film was also formed well. The physicochemical characteristics of CbFG and CbFG-film could be explained by the grafting of oleic acid onto chitosan in the absence of catalysts. In addition, CbFG containing oleic acid had a higher skin permeation rate in comparison with any other candidate enhancers. The in vivo efficacy study also confirmed significant anti-inflammatory and analgesic effects. Consequently, we report the successful preparation of chitosan-based film forming gel containing ketoprofen with excellent mechanical properties, skin permeation and anti-inflammatory and analgesic effects.

  14. Changes induced by UV radiation in the presence of sodium benzoate in films formulated with polyvinyl alcohol and carboxymethyl cellulose

    Energy Technology Data Exchange (ETDEWEB)

    Villarruel, S. [Faculty of Exact Sciences, UNLP (Argentina); Giannuzzi, L.; Rivero, S. [Center for Research and Development in Food Cryotechnology (CCT-CONICET La Plata), 47 and 116 (Argentina); Pinotti, A., E-mail: acaimpronta@hotmail.com [Center for Research and Development in Food Cryotechnology (CCT-CONICET La Plata), 47 and 116 (Argentina); Faculty of Engineering, UNLP, La Plata 1900 (Argentina)

    2015-11-01

    This work was focused on: i) developing single and blend films based on carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVOH) studying their properties, ii) analyzing the interactions between CMC and PVOH and their modifications UV-induced in the presence of sodium benzoate (SB), and iii) evaluating the antimicrobial capacity of blend films containing SB with and without UV treatment. Once the blend films with SB were exposed to UV radiation, they exhibited lower moisture content as well as a greater elongation at break and rougher surfaces compared to those without treatment. Considering oxygen barrier properties, the low values obtained would allow their application as packaging with selective oxygen permeability. Moreover, the characteristics of the amorphous phase of the matrix prevailed with a rearrangement of the structure of the polymer chain, causing a decrease of the crystallinity degree. These results were supported by X-rays and DSC analysis. FT-IR spectra reflected some degree of polymer–polymer interaction at a molecular level in the amorphous regions. The incorporation of sodium benzoate combined with UV treatment in blend films was positive from the microbial point of view because of the growth inhibition of a wide spectrum of microorganisms. From a physicochemical perspective, the UV treatment of films also changed their morphology rendering them more insoluble in water, turning the functionalized blend films into a potential material to be applied as food packaging. - Highlights: • CMC:PVOH blend films were developed with the addition of sodium benzoate (SB). • Exposition to UV radiation was carried out with sodium benzoate as photoinitiator. • Blend films were exposed to UV radiation to modify their surface morphology. • Low O{sub 2} permeability of UV treated blends allow them to be used as selective packaging. • Efficacy of SB as an antimicrobial agent was examined with and without UV radiation.

  15. Changes induced by UV radiation in the presence of sodium benzoate in films formulated with polyvinyl alcohol and carboxymethyl cellulose

    International Nuclear Information System (INIS)

    Villarruel, S.; Giannuzzi, L.; Rivero, S.; Pinotti, A.

    2015-01-01

    This work was focused on: i) developing single and blend films based on carboxymethyl cellulose (CMC) and polyvinyl alcohol (PVOH) studying their properties, ii) analyzing the interactions between CMC and PVOH and their modifications UV-induced in the presence of sodium benzoate (SB), and iii) evaluating the antimicrobial capacity of blend films containing SB with and without UV treatment. Once the blend films with SB were exposed to UV radiation, they exhibited lower moisture content as well as a greater elongation at break and rougher surfaces compared to those without treatment. Considering oxygen barrier properties, the low values obtained would allow their application as packaging with selective oxygen permeability. Moreover, the characteristics of the amorphous phase of the matrix prevailed with a rearrangement of the structure of the polymer chain, causing a decrease of the crystallinity degree. These results were supported by X-rays and DSC analysis. FT-IR spectra reflected some degree of polymer–polymer interaction at a molecular level in the amorphous regions. The incorporation of sodium benzoate combined with UV treatment in blend films was positive from the microbial point of view because of the growth inhibition of a wide spectrum of microorganisms. From a physicochemical perspective, the UV treatment of films also changed their morphology rendering them more insoluble in water, turning the functionalized blend films into a potential material to be applied as food packaging. - Highlights: • CMC:PVOH blend films were developed with the addition of sodium benzoate (SB). • Exposition to UV radiation was carried out with sodium benzoate as photoinitiator. • Blend films were exposed to UV radiation to modify their surface morphology. • Low O 2 permeability of UV treated blends allow them to be used as selective packaging. • Efficacy of SB as an antimicrobial agent was examined with and without UV radiation

  16. Formulation and optimization of a novel oral fast dissolving film containing drug nanoparticles by Box-Behnken design-response surface methodology.

    Science.gov (United States)

    Shen, Chengying; Shen, Baode; Xu, He; Bai, Jinxia; Dai, Ling; Lv, Qingyuan; Han, Jin; Yuan, Hailong

    2014-05-01

    The purpose of this study was to design and optimize a novel drug nanoparticles-loaded oral fast dissolving film (NP-OFDF) using Box-Behnken design-response surface methodology. Drug nanosuspensions produced from high pressure homogenization were transformed into oral fast dissolving film containing drug nanoparticles by casting methods. Herpetrione (HPE), a novel and potent antiviral agent with poor water solubility that was extracted from Herpetospermum caudigerum, was studied as the model drug. The formulations of oral fast dissolving film containing HPE nanoparticles (HPE-NP-OFDF) were optimized by employing Box-Behnken design-response surface methodology and then systematically characterized. The optimized HPE-NP-OFDF was disintegrated in water within 20 s with reconstituted nanosuspensions particle size of 299.31 nm. Scanning electron microscopy (SEM) images showed that well-dispersed HPE nanoparticles with slight adhesion to each other were exposed on the surface of film or embedded in film. The X-ray diffractogram (XRD) analysis suggested that HPE in the HPE-NP-OFDF was in the amorphous state. In-vitro release study, approximate 77.23% of HPE was released from the HPE-NP-OFDF within 5 min, which was more than eight times compared with that of HPE raw materials (9.57%). The optimized HPE-NP-OFDF exhibits much faster drug release rates compared to HPE raw material, which indicated that this novel NP-OFDF may provide a potential opportunity for oral delivery of drugs with poor water solubility.

  17. Indium--tin oxide films radio frequency sputtered from specially formulated high density indium--tin oxide targets

    International Nuclear Information System (INIS)

    Kulkarni, S.; Bayard, M.

    1991-01-01

    High density ITO (indium--tin oxide) targets doped with Al 2 O 3 and SiO 2 manufactured in the Tektronix Ceramics Division have been used to rf sputter ITO films of various thicknesses on borosilicate glass substrates. Sputtering in an oxygen--argon gas mixture and annealing in forming gas, resulted in ITO films exhibiting 90% transmission at 550 nm and a sheet resistance of 15 Ω/sq for a thickness of 1100 A. Sputtering in an oxygen--argon gas mixture and annealing in air increased sheet resistance without a large effect on the transmission. Films sputtered in argon gas alone were transparent in the visible and the sheet resistance was found to be 100--180 Ω/sq for the same thickness, without annealing

  18. Ceramic Composite Thin Films

    Science.gov (United States)

    Ruoff, Rodney S. (Inventor); Stankovich, Sasha (Inventor); Dikin, Dmitriy A. (Inventor); Nguyen, SonBinh T. (Inventor)

    2013-01-01

    A ceramic composite thin film or layer includes individual graphene oxide and/or electrically conductive graphene sheets dispersed in a ceramic (e.g. silica) matrix. The thin film or layer can be electrically conductive film or layer depending the amount of graphene sheets present. The composite films or layers are transparent, chemically inert and compatible with both glass and hydrophilic SiOx/silicon substrates. The composite film or layer can be produced by making a suspension of graphene oxide sheet fragments, introducing a silica-precursor or silica to the suspension to form a sol, depositing the sol on a substrate as thin film or layer, at least partially reducing the graphene oxide sheets to conductive graphene sheets, and thermally consolidating the thin film or layer to form a silica matrix in which the graphene oxide and/or graphene sheets are dispersed.

  19. Synthesis and Gas Transport Properties of Hyperbranched Polyimide–Silica Hybrid/Composite Membranes

    Directory of Open Access Journals (Sweden)

    Masako Miki

    2013-12-01

    Full Text Available Hyperbranched polyimide–silica hybrids (HBPI–silica HBDs and hyperbranched polyimide–silica composites (HBPI–silica CPTs were prepared, and their general and gas transport properties were investigated to clarify the effect of silica sources and preparation methods. HBPI–silica HBDs and HBPI–silica CPTs were synthesized by two-step polymerization of A2 + B3 monomer system via polyamic acid as precursor, followed by hybridizing or blending silica sources. Silica components were incorporated by the sol-gel reaction with tetramethoxysilane (TMOS or the addition of colloidal silica. In HBPI-silica HBDs, the aggregation of silica components is controlled because of the high affinity of HBPI and silica caused by the formation of covalent bonds between HBPI and silica. Consequently, HBPI-silica HBDs had good film formability, transparency, and mechanical properties compared with HBPI-silica CPTs. HBPI-silica HBD and CPT membranes prepared via the sol-gel reaction with TMOS showed specific gas permeabilities and permselectivities for CO2/CH4 separation, that is, both CO2 permeability and CO2/CH4 selectivity increased with increasing silica content. This result suggests that gas transport can occur through a molecular sieving effect of the porous silica network derived from the sol-gel reaction and/or through the narrow interfacial region between the silica networks and the organic matrix.

  20. Granulated decontamination formulations

    Science.gov (United States)

    Tucker, Mark D.

    2007-10-02

    A decontamination formulation and method of making that neutralizes the adverse health effects of both chemical and biological compounds, especially chemical warfare (CW) and biological warfare (BW) agents, and toxic industrial chemicals. The formulation provides solubilizing compounds that serve to effectively render the chemical and biological compounds, particularly CW and BW compounds, susceptible to attack, and at least one reactive compound that serves to attack (and detoxify or kill) the compound. The formulation includes at least one solubilizing agent, a reactive compound, a sorbent additive, and water. A highly adsorbent sorbent additive (e.g., amorphous silica, sorbitol, mannitol, etc.) is used to "dry out" one or more liquid ingredients into a dry, free-flowing powder that has an extended shelf life, and is more convenient to handle and mix in the field.

  1. Formulation and in vitro characterization of novel sildenafil citrate-loaded polyvinyl alcohol-polyethylene glycol graft copolymer-based orally dissolving films.

    Science.gov (United States)

    Xu, Li-Li; Shi, Li-Li; Cao, Qing-Ri; Xu, Wei-Juan; Cao, Yue; Zhu, Xiao-Yin; Cui, Jing-Hao

    2014-10-01

    This work was aimed to develop novel sildenafil citrate (SC)-loaded polyvinyl alcohol (PVA)-polyethylene glycol (PEG) graft copolymer (Kollicoat(®) IR)-based orally dissolving films (ODFs) using a solvent casting method. Formulation factors such as plasticizers and disintegrants were optimized on the basis of characteristics of blank ODFs. The SC-loaded ODF with a loading capacity up to 6.25mg in an area of 6 cm(2) was prepared and evaluated in terms of mechanical properties, disintegration time and dissolution rate. The physicochemical properties of drug-loaded ODF were also investigated using the scanning electron microscope (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR). The blank ODF composed of Kollicoat(®) IR, sodium alginate (ALG-Na) and glycerol (10:2:1.5, w/w) had a remarkably short disintegration time of about 20s. The SC-loaded ODF showed a delayed disintegration time (about 25s), but exhibited improved mechanical properties when compared to the blank ODF. SC was homogeneously dispersed throughout the ODF and the crystalline form of drug had been partly changed, existing strong hydrogen bonding between the drug and carriers. The Kollicoat(®) IR/ALG-Na based ODFs containing SC might be an alternative to conventional tablet for the treatment of male erectile dysfunction. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Silica artificial opal incorporated with silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Li Wenjiang, E-mail: wjli@zju.edu.cn [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China); Sun Tan [Center for Optical and Electromagnetic Research, State Key Laboratory for Modern Optical Instrumentation, Zhejiang University, Joint Research Center of Photonics of the Royal Institute of Technology and Zhejiang University, Zijingang Campus, Room 210, East Building 5, Hangzhou 310058 (China)

    2009-07-15

    The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

  3. Silica artificial opal incorporated with silver nanoparticles

    International Nuclear Information System (INIS)

    Li Wenjiang; Sun Tan

    2009-01-01

    The silica artificial opal with a three-dimensional (3D) periodic structure was prepared using highly monodispersed silica microspheres by a force packing method in ITO glass cell. The silica artificial opal incorporated with silver nanoparticles was fabricated by the electroplating technique. The optical microscope images of the synthetic sample and the corresponding optical properties were measured after each treatment of electroplating-washing-drying circle. The transmission and reflection spectra presented a red shift, showing that the effective refractive index of the complex silver/silica opal increased after each electroplating. Combining the SEM images, it was seen that the silver nanoparticles could be directly deposited on the surface of silica spheres in the opaline structure. The silver/silica complex opal film could provide a simple way to tune the opal properties by controlling silver nanoparticles in the silica opal. The silver/silica opal crystal structures could be used for nano-photonic circuits, white-light LEDs or as photocatalysts.

  4. On the controlled isotropic shrinkage induced fine-tuning of photo-luminescence in terbium ions embedded silica inverse opal films

    Science.gov (United States)

    Shrivastava, Vishnu Prasad; Kumar, Jitendra; Sivakumar, Sri

    2017-12-01

    Tb3+ embedded silica inverse opal structures with different photonic stop bands have been fabricated by annealing the SiO2-polystyrene spheres (diameter 390 nm) opal template at 320-650 oC. The PSB tuning realized in the wavelength range 498 - 600 nm is shown to depend on annealing temperature and impending isotropic shrinkage of silica matrix. The impact of wide PSB shift on four Tb3+ ion emission bands (blue, green, yellow, and red at 486, 545, 580, and 620 nm, respectively) corresponding to 5D4→7Fj (j = 6,5,4,3) transitions have been investigated. The effect amounts to significant suppression of emission bands at 586, 545 and 486 nm in inverse opals, obtained by annealing opal template at 350, 400, and 650 oC, respectively. Further, luminescence lifetime of Tb3+ ion 5D4 state increases with shrinkage induced in inverse opal progressively and get enhanced up to 2.3 times vis-à-vis reference silica. The changes in refractive index caused by thermal annealing of opal template is found to be responsible for the observed improvement in 5D4 state lifetime.

  5. Impregnação de filmes do compósito de policarbonato (PC e sílicagel (Si com corante fotocrômico em fluido supercrítico = Impregnation of composite from polycarbonate (PC and silica gel (Si films with photochromic dye in supercritical fluid

    Directory of Open Access Journals (Sweden)

    Fernanda de Almeida Fin de Lima

    2010-01-01

    Full Text Available O objetivo deste trabalho foi estudar a impregnação do corante fotocromático Reversacol Graphit® em filmes do compósito de policarbonato (PC e sílica-gel (Si, com a finalidade de obter aplicações em lentes fotocrômicas. Filmes de PC puros também foramimpregnados nas mesmas condições, para verificar o efeito da adição de sílica-gel. Os filmes do compósito foram produzidos em proporções de Si:PC de 1:40 e 1:80 (m m-1, pelo método casting. Para a impregnação do corante Reversacol Graphit nos filmes obtidos foiutilizado o processo supercrítico, pela sua eficiência e benefícios. A impregnação foi feita nos tempos de 15, 30, 45, 60, 90, 120, 150 e 180 min. A temperatura e a pressão adotadas foram de 60ºC e 120 bar. A quantidade de pigmento impregnado nos filmes de Si:PC – 1:40e 1:80 (m m-1 foi de 29 e 23% de massa de corante por massa de compósito, respectivamente, e para o filme de PC puro foi de apenas 2,2% massa de corante por massa de compósito. Pelas análises térmicas, verificou-se que os filmes do compósito apresentarammaior estabilidade térmica. Pela técnica de microscopia eletrônica, observou-se que os filmes de PC puro e dos compósitos Si:PC – 1:40 e 1:80 (m m-1 apresentaram uma superfície lisa e homogênea.The aim of this work was to study the impregnation of the photochromic dye Reversacol Graphit® in composite films ofpolycarbonate (PC and silica gel, with the purpose of finding applications in photochromic lenses. Pure PC films were also impregnated in the same conditions, to verify the effect of the silica-gel addition. The composites films were produced in Si:PC ratios of 1:40 and 1:80 (m m-1, using the casting method . For the impregnation of the dye Reversacol Graphit in the obtained films, the supercritical process was used due to its efficiency and benefits. The impregnation was made in the times of 15, 30, 45, 60, 90, 120, 150 and 180 minutes. The adopted temperature and pressure

  6. Functionalization of silica nanoparticles for polypropylene nanocomposites applications

    International Nuclear Information System (INIS)

    Bracho, Diego; Palza, Humberto; Quijada, Raul; Dougnac, Vivianne

    2011-01-01

    Synthetic silica nanospheres of different diameters produced via the sol-gel method were used in order to enhance the barrier properties of the polypropylene-silica nanocomposites. Modification of the silica surface by reaction with organic chlorosilanes was performed in order to improve the particles interaction with the polypropylene matrix and its dispersion. Unmodified and modified silica nanoparticles were characterized using electronic microscopy (TEM), elemental analysis, thermo gravimetric analysis (TGA), and solid state nuclear magnetic resonance (NMR) spectroscopy. Preliminary permeability tests of the polymer-silica nanocomposite films showed no significant change at low particles load (3 wt%) regardless its size or surface functionality, mainly because of the low aspect ratio of the silica nanospheres. However, it is expected that at a higher concentration of silica particles differences will be observed. (author)

  7. Steady-state leaching of tritiated water from silica gel

    DEFF Research Database (Denmark)

    Das, H.A.; Hou, Xiaolin

    2009-01-01

    Aqueous leaching of tritium from silica gel, loaded by absorption of water vapor, makes part of reactor de-commissioning. It is found to follow the formulation of steady-state diffusion.......Aqueous leaching of tritium from silica gel, loaded by absorption of water vapor, makes part of reactor de-commissioning. It is found to follow the formulation of steady-state diffusion....

  8. Plasma Polymerization of Acetylene onto silica: and Approach to control the distribution of silica in single elastomers and immiscible blends

    NARCIS (Netherlands)

    Tiwari, M.; Noordermeer, Jacobus W.M.; Ooij, W.J.; Dierkes, Wilma K.

    2008-01-01

    Surface modification of silica by acetylene plasma polymerization is applied in order to improve the dispersion in and compatibility with single rubbers and their blends. Silica, used as a reinforcing filler for elastomers, is coated with a polyacetylene (PA) film under vacuum conditions. Water

  9. Metal-silica sol-gel materials

    Science.gov (United States)

    Stiegman, Albert E. (Inventor)

    2002-01-01

    The present invention relates to a single phase metal-silica sol-gel glass formed by the co-condensation of a transition metal with silicon atoms where the metal atoms are uniformly distributed within the sol-gel glass as individual metal centers. Any transition metal may be used in the sol-gel glasses. The present invention also relates to sensor materials where the sensor material is formed using the single phase metal-silica sol-gel glasses. The sensor materials may be in the form of a thin film or may be attached to an optical fiber. The present invention also relates to a method of sensing chemicals using the chemical sensors by monitoring the chromatic change of the metal-silica sol-gel glass when the chemical binds to the sensor. The present invention also relates to oxidation catalysts where a metal-silica sol-gel glass catalyzes the reaction. The present invention also relates to a method of performing oxidation reactions using the metal-silica sol-gel glasses. The present invention also relates to organopolymer metal-silica sol-gel composites where the pores of the metal-silica sol-gel glasses are filled with an organic polymer polymerized by the sol-gel glass.

  10. Flexible and robust N-doped carbon nanofiber film encapsulating uniformly silica nanoparticles: Free-standing long-life and low-cost electrodes for Li- and Na-Ion batteries

    International Nuclear Information System (INIS)

    Li, Liye; Liu, Pengcheng; Zhu, Kongjun; Wang, Jing; Tai, Guoan; Liu, Jinsong

    2017-01-01

    With the wearable electronics progressing rapidly, the demand for flexible, long-life and low-cost electrodes of Li-ion batteries (LIBs) becomes more and more urgent. Due to the abundant resources and low cost, silica (SiO_2), especially the amorphous one, has attracted a lot of interests on the application of anode materials for LIBs. However, SiO_2 still suffer from the poor cycling performance mainly caused by the huge volume change during cycling like other alloy-type materials. Furthermore, it remains a challenge to fabricate the SiO_2–based flexible electrode. Herein, we propose a facile in situ strategy to fabricate the electrospun robust free-standing SiO_2/carbon nanofibers (denoted as in-SCNFs) film constructed by N-doped carbon nanofibers encapsulating uniformly amorphous SiO_2 nanoparticles. The in situ synthesized finer SiO_2 nanoparticles in the in-SCNFs are uniformly encapsulated in flexible carbon nanofibers, which can effectively buffer the volume change. Furthermore, the robust in-SCNFs film possesses the excellent mechanical flexibility and strength. So, when served as the free-standing anode of LIBs, the in-SCNFs film exhibits superior cycling performance. A discharge specific capacity of 405 mAh/g can be delivered even after a long-term 1000 cycles at a large current density of 500 mA/g, and the retention is up to 115%. It is an exciting finding that the in-SCNFs film is also a long-life anode of Na-ion batteries (NIBs). The 99% of initial capacity can be kept after 250 cycles at 500 mA/g. To our best knowledge, this is the first report on the application of SiO_2/C composite for NIBs. These results suggest that the as-fabricated in-SCNFs film can become one promising free-standing long-life anode for LIBs and NIBs.

  11. Preferential adsorption of polycarboxylate superplasticizers on cement and silica fume in ultra-high performance concrete (UHPC)

    International Nuclear Information System (INIS)

    Schröfl, Ch.; Gruber, M.; Plank, J.

    2012-01-01

    UHPC is fluidized particularly well when a blend of MPEG- and APEG-type PCEs is applied. Here, the mechanism for this behavior was investigated. Testing individual cement and micro silica pastes revealed that the MPEG-PCE disperses cement better than silica whereas the APEG-PCE fluidizes silica particularly well. This behavior is explained by preferential adsorption of APEG-PCE on silica while MPEG-PCEs exhibit a more balanced affinity to both cement and silica. Adsorption data obtained from individual cement and micro silica pastes were compared with those found for the fully formulated UHPC containing a cement/silica blend. In the UHPC formulation, both PCEs still exhibit preferential and selective adsorption similar as was observed for individual cement and silica pastes. Preferential adsorption of PCEs is explained by their different stereochemistry whereby the carboxylate groups have to match with the steric position of calcium ions/atoms situated at the surfaces of cement hydrates or silica.

  12. Hybrid silica luminescent materials based on lanthanide-containing lyotropic liquid crystal with polarized emission

    Energy Technology Data Exchange (ETDEWEB)

    Selivanova, N.M., E-mail: natsel@mail.ru [Kazan National Research Technological University, 68 Karl Marx Str., Kazan 420015 (Russian Federation); Vandyukov, A.E.; Gubaidullin, A.T. [A.E. Arbuzov Institute of Organic and Physical Chemistry of the Kazan Scientific Center of the Russian Academy of Sciences, 8 Acad. Arbuzov Str., Kazan 420088 (Russian Federation); Galyametdinov, Y.G. [Kazan National Research Technological University, 68 Karl Marx Str., Kazan 420015 (Russian Federation)

    2014-11-14

    This paper represents the template method for synthesis of hybrid silica films based on Ln-containing lyotropic liquid crystal and characterized by efficient luminescence. Luminescence films were prepared in situ by the sol–gel processes. Lyotropic liquid crystal (LLC) mesophases C{sub 12}H{sub 25}O(CH{sub 2}CH{sub 2}O){sub 10}H/Ln(NO{sub 3}){sub 3}·6H{sub 2}O/H{sub 2}O containing Ln (III) ions (Dy, Tb, Eu) were used as template. Polarized optical microscopy, X-ray powder diffraction, and FT-IR-spectroscopy were used for characterization of liquid crystal mesophases and hybrid films. The morphology of composite films was studied by the atomic force microscopy method (AFM). The optical properties of the resulting materials were evaluated. It was found that hybrid silica films demonstrate significant increase of their lifetime in comparison with an LLC system. New effects of linearly polarized emission revealed for Ln-containing hybrid silica films. Polarization in lanthanide-containing hybrid composites indicates that silica precursor causes orientation of emitting ions. - Highlights: • We suggest a new simple approach for creating luminescence hybrid silica films. • Ln-containing hybrid silica films demonstrate yellow, green and red emissions. • Tb(III)-containing hybrid film have a high lifetime. • We report effects of linearly polarized emission in hybrid film.

  13. Control of silicification by genetically engineered fusion proteins: Silk–silica binding peptides

    Science.gov (United States)

    Zhou, Shun; Huang, Wenwen; Belton, David J.; Simmons, Leo O.; Perry, Carole C.; Wang, Xiaoqin; Kaplan, David L.

    2014-01-01

    In the present study, an artificial spider silk gene, 6mer, derived from the consensus sequence of Nephila clavipes dragline silk gene, was fused with different silica-binding peptides (SiBPs), A1, A3 and R5, to study the impact of the fusion protein sequence chemistry on silica formation and the ability to generate a silk–silica composite in two different bioinspired silicification systems: solution–solution and solution– solid. Condensed silica nanoscale particles (600–800 nm) were formed in the presence of the recombinant silk and chimeras, which were smaller than those formed by 15mer-SiBP chimeras [1], revealing that the molecular weight of the silk domain correlated to the sizes of the condensed silica particles in the solution system. In addition, the chimeras (6mer-A1/A3/R5) produced smaller condensed silica particles than the control (6mer), revealing that the silica particle size formed in the solution system is controlled by the size of protein assemblies in solution. In the solution–solid interface system, silicification reactions were performed on the surface of films fabricated from the recombinant silk proteins and chimeras and then treated to induce β-sheet formation. A higher density of condensed silica formed on the films containing the lowest β-sheet content while the films with the highest β-sheet content precipitated the lowest density of silica, revealing an inverse correlation between the β-sheet secondary structure and the silica content formed on the films. Intriguingly, the 6mer-A3 showed the highest rate of silica condensation but the lowest density of silica deposition on the films, compared with 6mer-A1 and -R5, revealing antagonistic crosstalk between the silk and the SiBP domains in terms of protein assembly. These findings offer a path forward in the tailoring of biopolymer–silica composites for biomaterial related needs. PMID:25462851

  14. Microporous silica membranes

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Yue, Yuanzheng

    2012-01-01

    Hydrothermal stability is a crucial factor for the application of microporous silica-based membranes in industrial processes. Indeed, it is well established that steam exposure may cause densification and defect formation in microporous silica membranes, which are detrimental to both membrane...... permeability and selectivity. Numerous previous studies show that microporous transition metal doped-silica membranes are hydrothermally more stable than pure silica membranes, but less permeable. Here we present a quantitative study on the impact of type and concentration of transition metal ions...... on the microporous structure, stability and permeability of amorphous silica-based membranes, providing information on how to design chemical compositions and synthetic paths for the fabrication of silica-based membranes with a well accessible and highly stabile microporous structure....

  15. Fabrication of transparent superhydrophobic glass with fibered-silica network

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Feng [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province & Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006 (China); Shi, Zhenwu, E-mail: zwshi@suda.edu.cn [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province & Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006 (China); Jiang, Yingjie; Xu, Chengyun; Wu, Zhuhui; Wang, Yanyan [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province & Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006 (China); Peng, Changsi, E-mail: changsipeng@suda.edu.cn [College of Physics, Optoelectronics and Energy & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215006 (China); Key Lab of Advanced Optical Manufacturing Technologies of Jiangsu Province & Key Lab of Modern Optical Technologies of Education Ministry of China, Soochow University, Suzhou 215006 (China)

    2017-06-15

    Highlights: • Superhydrophobic fibred-silica film with water contact angle of 166° and sliding angle of 1° was efficiently prepared using soot as template by CVD. • The film showed transmittance of 88% in visible range. • The superhydrophobic film possesses excellent mechanical robustness, chemical corrosion resistance, and thermal stability. • The superhydrophobic film showed outstanding self-cleaning behavior. - Abstract: In this paper, silica was deposited on the soot film pre-coated glass via chemical vapor deposition. Through calcination at 500 °C with the assistance of O{sub 2} airflow, the soot film was removed and a novel robust fibered-silica network film was then decorated onto the glass substrate. After modification with fluorosilane, the surface water contact angle (WCA) was 166° and sliding angle (SA) was 1° which behaves a good self-cleaning for the as-prepared glass. And its average transmittance was still over 88% in visible wavelength. Moreover, this fibered-silica coating showed a strong tolerance for heavy water droplets, acid/alkali corrosion, salt solution immersion and thermal treatment.

  16. What Is Crystalline Silica?

    Science.gov (United States)

    ... and ceramic manufacturing and the tool and die, steel and foundry industries. Crystalline silica is used in manufacturing, household abrasives, adhesives, paints, soaps, and glass. Additionally, ...

  17. Selective porous gates made from colloidal silica nanoparticles

    Directory of Open Access Journals (Sweden)

    Roberto Nisticò

    2015-11-01

    Full Text Available Highly selective porous films were prepared by spin-coating deposition of colloidal silica nanoparticles on an appropriate macroporous substrate. Silica nanoparticles very homogenous in size were obtained by sol–gel reaction of a metal oxide silica precursor, tetraethyl orthosilicate (TEOS, and using polystyrene-block-poly(ethylene oxide (PS-b-PEO copolymers as soft-templating agents. Nanoparticles synthesis was carried out in a mixed solvent system. After spin-coating onto a macroporous silicon nitride support, silica nanoparticles were calcined under controlled conditions. An organized nanoporous layer was obtained characterized by a depth filter-like structure with internal porosity due to interparticle voids. Permeability and size-selectivity were studied by monitoring the diffusion of probe molecules under standard conditions and under the application of an external stimulus (i.e., electric field. Promising results were obtained, suggesting possible applications of these nanoporous films as selective gates for controlled transport of chemical species in solution.

  18. Fabrication of keratin-silica hydrogel for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Kakkar, Prachi; Madhan, Balaraman, E-mail: bmadhan76@yahoo.co.in

    2016-09-01

    In the recent past, keratin has been fabricated into different forms of biomaterials like scaffold, gel, sponge, film etc. In lieu of the myriad advantages of the hydrogels for biomedical applications, a keratin-silica hydrogel was fabricated using tetraethyl orthosilicate (TEOS). Textural analysis shed light on the physical properties of the fabricated hydrogel, inturn enabling the optimization of the hydrogel. The optimized keratin-silica hydrogel was found to exhibit instant springiness, optimum hardness, with ease of spreadability. Moreover, the hydrogel showed excellent swelling with highly porous microarchitecture. MTT assay and DAPI staining revealed that keratin-silica hydrogel was biocompatible with fibroblast cells. Collectively, these properties make the fabricated keratin-silica hydrogel, a suitable dressing material for biomedical applications. - Highlights: • Keratin-silica hydrogel has been fabricated using sol–gel technique. • The hydrogel shows appropriate textural properties. • The hydrogel promotes fibroblast cells proliferation. • The hydrogel has potential soft tissue engineering applications like wound healing.

  19. Crystalline Silica Primer

    Science.gov (United States)

    ,

    1992-01-01

    Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. The term crystalline refers to the fact that the oxygen and silicon atoms are arranged in a threedimensional repeating pattern. This group of minerals has shaped human history since the beginning of civilization. From the sand used for making glass to the piezoelectric quartz crystals used in advanced communication systems, crystalline silica has been a part of our technological development. Crystalline silica's pervasiveness in our technology is matched only by its abundance in nature. It's found in samples from every geologic era and from every location around the globe. Scientists have known for decades that prolonged and excessive exposure to crystalline silica dust in mining environments can cause silicosis, a noncancerous lung disease. During the 1980's, studies were conducted that suggested that crystalline silica also was a carcinogen. As a result of these findings, crystalline silica has been regulated under the Occupational Safety and Health Administration's (OSHA) Hazard Communication Standard (HCS). Under HCS, OSHAregulated businesses that use materials containing 0.1% or more crystalline silica must follow Federal guidelines concerning hazard communication and worker training. Although the HCS does not require that samples be analyzed for crystalline silica, mineral suppliers or OSHAregulated

  20. Oxygen configurations in silica

    International Nuclear Information System (INIS)

    Chelikowsky, James R.; Chadi, D. J.; Binggeli, N.

    2000-01-01

    We propose a transition state for oxygen in silica. This state is produced by the insertion of an oxygen molecule into the Si-O-Si bond, i.e., it consists of producing a Si-O-O-O-Si bond. This state allows molecular oxygen diffusion in silica without breaking the molecular O 2 bond and it is energetically more stable than a peroxy configuration. This configuration may allow for exchange of molecular oxygen with the oxygen in the silica framework. (c) 2000 The American Physical Society

  1. Silica coatings on clarithromycin.

    Science.gov (United States)

    Bele, Marjan; Dmitrasinovic, Dorde; Planinsek, Odon; Salobir, Mateja; Srcic, Stane; Gaberscek, Miran; Jamnik, Janko

    2005-03-03

    Pre-crystallized clarithromycin (6-O-methylerythromycin A) particles were coated with silica from the tetraethyl orthosilicate (TEOS)-ethanol-aqueous ammonia system. The coatings had a typical thickness of 100-150 nm and presented about 15 wt.% of the silica-drug composite material. The properties of the coatings depended on reactant concentration, temperature and mixing rate and, in particular, on the presence of a cationic surfactant (cetylpyridinium chloride). In the presence of cetylpyridinium chloride the silica coatings slightly decreased the rate of pure clarithromycin dissolution.

  2. Silica aerogel Cerenkov counter

    International Nuclear Information System (INIS)

    Yasumi, S.; Masaike, A.; Yamamoto, A.; Yoshimura, Y.; Kawai, H.

    1984-03-01

    In order to obtain silica aerogel radiators of good quality, the prescription used by Saclay group has been developed. We have done several experiments using beams from KEK.PS to test the performance of a Cerenkov counter with aerogel modules produced in KEK. It turned out that these modules had excellent quality. The production rate of silica aerogel in KEK is 15 -- 20 litres a week. Silica aerogel modules of 20 x 10 x 3 cm 3 having the refractive index of 1.058 are successfully being used by Kyoto University group in the KEK experiment E92 (Σ). Methodes to produce silica aerogel with higher refractive index than 1.06 has been investigated both by heating an module with the refractive index of 1.06 and by hydrolyzing tetraethyl silicate. (author)

  3. Two-dimensional silica opens new perspectives

    Science.gov (United States)

    Büchner, Christin; Heyde, Markus

    2017-12-01

    In recent years, silica films have emerged as a novel class of two-dimensional (2D) materials. Several groups succeeded in epitaxial growth of ultrathin SiO2 layers using different growth methods and various substrates. The structures consist of tetrahedral [SiO4] building blocks in two mirror symmetrical planes, connected via oxygen bridges. This arrangement is called a silica bilayer as it is the thinnest 2D arrangement with the stoichiometry SiO2 known today. With all bonds saturated within the nano-sheet, the interaction with the substrate is based on van der Waals forces. Complex ring networks are observed, including hexagonal honeycomb lattices, point defects and domain boundaries, as well as amorphous domains. The network structures are highly tuneable through variation of the substrate, deposition parameters, cooling procedure, introducing dopants or intercalating small species. The amorphous networks and structural defects were resolved with atomic resolution microscopy and modeled with density functional theory and molecular dynamics. Such data contribute to our understanding of the formation and characteristic motifs of glassy systems. Growth studies and doping with other chemical elements reveal ways to tune ring sizes and defects as well as chemical reactivities. The pristine films have been utilized as molecular sieves and for confining molecules in nanocatalysis. Post growth hydroxylation can be used to tweak the reactivity as well. The electronic properties of silica bilayers are favourable for using silica as insulators in 2D material stacks. Due to the fully saturated atomic structure, the bilayer interacts weakly with the substrate and can be described as quasi-freestanding. Recently, a mm-scale film transfer under structure retention has been demonstrated. The chemical and mechanical stability of silica bilayers is very promising for technological applications in 2D heterostacks. Due to the impact of this bilayer system for glass science

  4. Effects of Silica Nanostructures in Poly(ethylene oxide)-Based Composite Polymer Electrolytes.

    Science.gov (United States)

    Mohanta, Jagdeep; Anwar, Shahid; Si, Satyabrata

    2016-06-01

    The present work describes the synthesis of some poly(ethylene oxide)-based nanocomposite polymer electrolyte films using various silica nanostructures as the inorganic filler by simple solution mixing technique, in which the nature of the silica nanostructures play a vital role in modulating their electrochemical performances at room temperature. The silica nanostructures are prepared by ammonical hydrolysis of tetraethyl orthosilicate following the modified St6ber method. The resulting films are characterized by X-ray diffraction and differential scanning calorimeter to study their crystallinity. Room temperature AC impedance spectroscopy is utilized to determine the Li+ ion conductivity of the resulting films. The observed conductivity values of various NCPE films depend on the nature of silica filling as well as on their surface characteristics and also on the varying PEO-Li+ ratio, which is observed to be in the order of 10(-7)-10(-6) S cm(-1).

  5. Bidisperse silica nanoparticles close-packed monolayer on silicon substrate by three step spin method

    Science.gov (United States)

    Khanna, Sakshum; Marathey, Priyanka; Utsav, Chaliawala, Harsh; Mukhopadhyay, Indrajit

    2018-05-01

    We present the studies on the structural properties of monolayer Bidisperse silica (SiO2) nanoparticles (BDS) on Silicon (Si-100) substrate using spin coating technique. The Bidisperse silica nanoparticle was synthesised by the modified sol-gel process. Nanoparticles on the substrate are generally assembled in non-close/close-packed monolayer (CPM) form. The CPM form is obtained by depositing the colloidal suspension onto the silicon substrate using complex techniques. Here we report an effective method for forming a monolayer of bidisperse silica nanoparticle by three step spin coating technique. The samples were prepared by mixing the monodisperse solutions of different particles size 40 and 100 nm diameters. The bidisperse silica nanoparticles were self-assembled on the silicon substrate forming a close-packed monolayer film. The scanning electron microscope images of bidisperse films provided in-depth film structure of the film. The maximum surface coverage obtained was around 70-80%.

  6. Enhanced microcontact printing of proteins on nanoporous silica surface

    Energy Technology Data Exchange (ETDEWEB)

    Blinka, Ellen; Hu Ye; Gopal, Ashwini; Hoshino, Kazunori; Lin, Kevin; Zhang, John X J [Department of Biomedical Engineering, University of Texas at Austin, Austin, TX 78758 (United States); Loeffler, Kathryn; Liu Xuewu; Ferrari, Mauro, E-mail: John.Zhang@engr.utexas.edu [Department of Nanomedicine and Biomedical Engineering, University of Texas Health Science Service, Houston, TX 77031 (United States)

    2010-10-15

    We demonstrate porous silica surface modification, combined with microcontact printing, as an effective method for enhanced protein patterning and adsorption on arbitrary surfaces. Compared to conventional chemical treatments, this approach offers scalability and long-term device stability without requiring complex chemical activation. Two chemical surface treatments using functionalization with the commonly used 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde (GA) were compared with the nanoporous silica surface on the basis of protein adsorption. The deposited thickness and uniformity of porous silica films were evaluated for fluorescein isothiocyanate (FITC)-labeled rabbit immunoglobulin G (R-IgG) protein printed onto the substrates via patterned polydimethlysiloxane (PDMS) stamps. A more complete transfer of proteins was observed on porous silica substrates compared to chemically functionalized substrates. A comparison of different pore sizes (4-6 nm) and porous silica thicknesses (96-200 nm) indicates that porous silica with 4 nm diameter, 57% porosity and a thickness of 96 nm provided a suitable environment for complete transfer of R-IgG proteins. Both fluorescence microscopy and atomic force microscopy (AFM) were used for protein layer characterizations. A porous silica layer is biocompatible, providing a favorable transfer medium with minimal damage to the proteins. A patterned immunoassay microchip was developed to demonstrate the retained protein function after printing on nanoporous surfaces, which enables printable and robust immunoassay detection for point-of-care applications.

  7. Study of silica sol-gel materials for sensor development

    Science.gov (United States)

    Lei, Qiong

    Silica sol-gel is a transparent, highly porous silicon oxide glass made at room temperature by sol-gel process. The name of silica sol-gel comes from the observable physical phase transition from liquid sol to solid gel during its preparation. Silica sol-gel is chemically inert, thermally stable, and photostable, it can be fabricated into different desired shapes during or after gelation, and its porous structure allows encapsulation of guest molecules either before or after gelation while still retaining their functions and sensitivities to surrounding environments. All those distinctive features make silica sol-gel ideal for sensor development. Study of guest-host interactions in silica sol-gel is important for silica-based sensor development, because it helps to tailor local environments inside sol-gel matrix so that higher guest loading, longer shelf-life, higher sensitivity and faster response of silica gel based sensors could be achieved. We focused on pore surface modification of two different types of silica sol-gel by post-grafting method, and construction of stable silica hydrogel-like thin films for sensor development. By monitoring the mobility and photostability of rhodamine 6G (R6G) molecules in silica alcogel thin films through single molecule spectroscopy (SMS), the guest-host interactions altered by post-synthesis grafting were examined. While physical confinement remains the major factor that controls mobility in modified alcogels, both R6G mobility and photostability register discernable changes after surface charges are respectively reversed and neutralized by aminopropyltriethoxysilane (APTS) and methyltriethoxysilane (MTES) grafting. The change in R6G photostability was found to be more sensitive to surface grafting than that of mobility. In addition, silica film modification by 0.4% APTS is as efficient as that by pure MTES in lowering R6G photostability, which suggests that surface charge reversal is more effective than charge neutralization

  8. Fabrication of semi-transparent super-hydrophobic surface based on silica hierarchical structures

    KAUST Repository

    Chen, Ping-Hei

    2011-01-01

    This study successfully develops a versatile method of producing superhydrophobic surfaces with micro/nano-silica hierarchical structures on glass surfaces. Optically transparent super hydrophobic silica thin films were prepared by spin-coating silica particles suspended in a precursor solution of silane, ethanol, and H2O with molar ratio of 1:4:4. The resulting super hydrophobic films were characterized by scanning electron microscopy (SEM), optical transmission, and contact angle measurements. The glass substrates in this study were modified with different particles: micro-silica particles, nano-silica particles, and hierarchical structures. This study includes SEM micrographs of the modified glass surfaces with hierarchical structures at different magnifications. © 2011 The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.

  9. Supramolecular Complex Antioxidant Consisting of Vitamins C, E and Hydrophilic-Hydrophobic Silica Nanoparticles

    Science.gov (United States)

    Laguta, I. V.; Kuzema, P. O.; Stavinskaya, O. N.; Kazakova, O. A.

    Samples with varied amount of surface trimethylsilyl groups were obtained via gas-phase chemical modification of silica nanoparticles. The biocompatibility tests conducted in erythrocyte suspension have shown that hydrophobization of silica decreases its damaging effect to the cells. Being wettable in aqueous media, partially silylated silicas have higher affinity to hydrophobic bioactive molecules in comparison with the initial silica. Novel antioxidant consisting of vitamins C and E and silica with 40% of surface trimethylsilyl groups was formulated. It was found that supramolecular complexes are formed on the silica surface due to the affinity of water- and fat-soluble antioxidants to hydrophilic silanol and hydrophobic trimethylsilyl groups, respectively. Test reactions (total phenolic index determination, DPPH test) and in vitro studies (spectral analysis of erythrocyte suspensions undergoing UV irradiation) revealed the correlation between antioxidant activity of the complex antioxidant and the vitamins’ content. The antioxidant remained active during long-term storage under standard conditions.

  10. Rapid and sensitive electrochemical determination of codeine in pharmaceutical formulations and human urine using a boron-doped diamond film electrode

    International Nuclear Information System (INIS)

    Švorc, Ľubomír; Sochr, Jozef; Svítková, Jana; Rievaj, Miroslav; Bustin, Dušan

    2013-01-01

    Highlights: ► Novel electrochemical sensor for the determination of codeine is presented. ► Codeine provided a single oxidation peak at +1.0 V vs. Ag/AgCl in BRBS at pH 7. ► Detection limit of 0.08 μM was achieved without electrode surface modification. ► Benefits of method: rapidity, low cost, low elaborateness and high repeatability. ► Possibility for drug quality control and drug analysis of biological samples. - Abstract: An unmodified boron-doped diamond film electrode was used for the first time as a sensitive and selective electrochemical sensor for the determination of codeine by the use of differential pulse voltammetry. Codeine provided a single well-defined oxidation peak at +1.0 V vs. Ag/AgCl in Britton-Robinson buffer solution at pH 7.0. Using the optimal differential pulse voltammetric conditions (modulation amplitude of 50 mV, modulation time of 40 ms and scan rate of 50 mV s −1 ), the detection limit of 0.08 μM, the linear response of peak current on codeine concentration in the range from 0.1 to 60 μM (R 2 = 0.998, n = 6) and relative standard deviation of 0.9% at 10 μM concentration level (n = 10) were achieved without any electrode surface modification. The influence of potential interfering agents on the current response was also studied and the results indicated that the proposed method was sufficiently selective. The method was successfully applied in the determination of codeine in real samples including pharmaceutical tablets and human urine with results similar to those declared by manufacturer and obtained by reference high-performance liquid chromatography method, respectively. The typical benefits of the method may be summarized as: rapidity (20 determinations per hour), sensitivity and selectivity, low cost and elaborateness, simplicity, wide linear concentration range, low detection limit and excellent repeatability. It might also represent the competitive alternative to the existing analytical methods in monitoring of

  11. Silica-Immobilized Enzyme Reactors

    Science.gov (United States)

    2007-08-01

    Silica-IMERs 14 implicated in neurological disorders such as Schizophrenia and Parkinson’s disease.[86] Drug discovery for targets that can alter the...primarily the activation of prodrugs and proantibiotics for cancer treatments or antibiotic therapy , respectively.[87] Nitrobenzene nitroreductase was...BuChE) Monolith disks* Packed Silica Biosilica Epoxide- Silica Silica-gel Enzyme Human AChE Human AChE Human AChE Equine BuChE Human

  12. Silica reinforced triblock copolymer gels

    DEFF Research Database (Denmark)

    Theunissen, E.; Overbergh, N.; Reynaers, H.

    2004-01-01

    The effect of silica and polymer coated silica particles as reinforcing agents on the structural and mechanical properties of polystyrene-poly(ethylene/butylene)-polystyrene (PS-PEB-PS) triblock gel has been investigated. Different types of chemically modified silica have been compared in order...

  13. Silica from Ash

    Indian Academy of Sciences (India)

    management, polymer composites and chemical process design. Figure 1 Difference in color of the ash ... The selection of ash is important as the quality of ash determines the total amount as well as quality of silica recoverable Ash which has undergone maximum extent of combustion is highly desirable as it contains ...

  14. Hydrothermal stability of silica, hybrid silica and Zr-doped hybrid silica membranes

    NARCIS (Netherlands)

    ten Hove, Marcel; Luiten-Olieman, Mieke W.J.; Huiskes, Cindy; Nijmeijer, Arian; Winnubst, Louis

    2017-01-01

    Hybrid silica membranes have demonstrated to possess a remarkable hydrothermal stability in pervaporation and gas separation processes allowing them to be used in industrial applications. In several publications the hydrothermal stability of pure silica or that of hybrid silica membranes are

  15. Formulating a low-alkalinity cement for radioactive waste repositories

    International Nuclear Information System (INIS)

    Coumes, C. Cau Dit; Courtois, S.; Leclercq, S.; Bourbon, X.

    2004-01-01

    A multi-annual research program has been launched in January 2003 by CEA, EDF and ANDRA in order to formulate and characterize low-alkalinity and low-heat cements which would be compatible with an underground waste repository environment. Four types of bindings have been investigated: binary blends of Portland cement and silica fume or metakaolin, as well as ternary blends of Portland cement, fly ash and silica fume or metakaolin. Promising results have been obtained with a mixture comprising 37.5% Portland cement, 32.5% silica fume, and 30% fly ash: pH of water in equilibrium with fully hydrated cement is below 11. Moreover, silica fume compensates for the low reactivity of fly ash, while fly ash allows to reduce water demand, heat release, and dimensional variations of cement pastes and mortars. (authors)

  16. Formulating a low-alkalinity cement for radioactive waste repositories

    Energy Technology Data Exchange (ETDEWEB)

    Coumes, C. Cau Dit; Courtois, S.; Leclercq, S.; Bourbon, X

    2004-07-01

    A multi-annual research program has been launched in January 2003 by CEA, EDF and ANDRA in order to formulate and characterize low-alkalinity and low-heat cements which would be compatible with an underground waste repository environment. Four types of bindings have been investigated: binary blends of Portland cement and silica fume or metakaolin, as well as ternary blends of Portland cement, fly ash and silica fume or metakaolin. Promising results have been obtained with a mixture comprising 37.5% Portland cement, 32.5% silica fume, and 30% fly ash: pH of water in equilibrium with fully hydrated cement is below 11. Moreover, silica fume compensates for the low reactivity of fly ash, while fly ash allows to reduce water demand, heat release, and dimensional variations of cement pastes and mortars. (authors)

  17. Addition of Silica Fume to Improve Strength of Cement Paste

    Science.gov (United States)

    Chen, Jiajian; Chen, Hongniao; Li, Gu

    2018-03-01

    This study measured the packing densities of 0 to 30% silica fume (SF) added cementitious materials and strength of the cementitious pastes with various water content. The results revealed that addition of silica fume up to a certain level has great effects on packing density and strength. In-depth analysis illustrated that a lower W/CM ratio would not always result in a higher cube strength, and the range between 0.05 and 0.07 µm would be the amount of water film thickness (WFT) for muximum strength.

  18. Crystallization Formulation Lab

    Data.gov (United States)

    Federal Laboratory Consortium — The Crystallization Formulation Lab fills a critical need in the process development and optimization of current and new explosives and energetic formulations. The...

  19. Control of silicification by genetically engineered fusion proteins: silk-silica binding peptides.

    Science.gov (United States)

    Zhou, Shun; Huang, Wenwen; Belton, David J; Simmons, Leo O; Perry, Carole C; Wang, Xiaoqin; Kaplan, David L

    2015-03-01

    In the present study, an artificial spider silk gene, 6mer, derived from the consensus sequence of Nephila clavipes dragline silk gene, was fused with different silica-binding peptides (SiBPs), A1, A3 and R5, to study the impact of the fusion protein sequence chemistry on silica formation and the ability to generate a silk-silica composite in two different bioinspired silicification systems: solution-solution and solution-solid. Condensed silica nanoscale particles (600-800 nm) were formed in the presence of the recombinant silk and chimeras, which were smaller than those formed by 15mer-SiBP chimeras, revealing that the molecular weight of the silk domain correlated to the sizes of the condensed silica particles in the solution system. In addition, the chimeras (6mer-A1/A3/R5) produced smaller condensed silica particles than the control (6mer), revealing that the silica particle size formed in the solution system is controlled by the size of protein assemblies in solution. In the solution-solid interface system, silicification reactions were performed on the surface of films fabricated from the recombinant silk proteins and chimeras and then treated to induce β-sheet formation. A higher density of condensed silica formed on the films containing the lowest β-sheet content while the films with the highest β-sheet content precipitated the lowest density of silica, revealing an inverse correlation between the β-sheet secondary structure and the silica content formed on the films. Intriguingly, the 6mer-A3 showed the highest rate of silica condensation but the lowest density of silica deposition on the films, compared with 6mer-A1 and -R5, revealing antagonistic crosstalk between the silk and the SiBP domains in terms of protein assembly. These findings offer a path forward in the tailoring of biopolymer-silica composites for biomaterial related needs. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  20. Mesoporous Silica Molecular Sieve based Nanocarriers: Transpiring Drug Dissolution Research.

    Science.gov (United States)

    Pattnaik, Satyanarayan; Pathak, Kamla

    2017-01-01

    Improvement of oral bioavailability through enhancement of dissolution for poorly soluble drugs has been a very promising approach. Recently, mesoporous silica based molecular sieves have demonstrated excellent properties to enhance the dissolution velocity of poorly water-soluble drugs. Current research in this area is focused on investigating the factors influencing the drug release from these carriers, the kinetics of drug release and manufacturing approaches to scale-up production for commercial manufacture. This comprehensive review provides an overview of different methods adopted for synthesis of mesoporous materials, influence of processing factors on properties of these materials and drug loading methods. The drug release kinetics from mesoporous silica systems, the manufacturability and stability of these formulations are reviewed. Finally, the safety and biocompatibility issues related to these silica based materials are discussed. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  1. In Situ Growth of Mesoporous Silica with Drugs on Titanium Surface and Its Biomedical Applications.

    Science.gov (United States)

    Wan, Mimi; Zhang, Jin; Wang, Qi; Zhan, Shuyue; Chen, Xudong; Mao, Chun; Liu, Yuhong; Shen, Jian

    2017-06-07

    Mesoporous silica has been developed for the modification of titanium surfaces that are used as implant materials. Yet, the traditional modification methods failed to effectively construct mesoporous silica on the titanium surface evenly and firmly, in which the interaction between mesoporous silica and titanium was mainly physical. Here, in situ growth of mesoporous silica on a titanium surface was performed using a simple evaporation-induced self-assembly strategy. Meantime, in situ introduction of drugs (heparin and vancomycin) to mesoporous silica was also adopted to improve the drug-loading amount. Both the above-mentioned processes were completed at the same time. Transmission electron microscopy, N 2 adsorption-desorption isotherms, Fourier transform infrared spectroscopy, scanning electron microscopy, and water contact angle measurements were used to characterize the structure of the mesoporous silica film. Results indicated that the mesoporous silica film that in situ grew on the titanium surface was smooth, thin, transparent, and stable. Cytotoxicity, proliferation performance of osteoblast cells, and in vitro and in vivo studies of the antibacterial activity of the coating were tested. This is the first study to modify the titanium surface by the in situ growth of a mesoporous silica coating with two kinds of drugs. The stability of the mesoporous silica coating can be attributed to the chemical bonding between dopamine and silicon hydroxyl of the mesoporous silica coating, and the smooth surface of mesoporous silica is a result of the method of in situ growth. The large amount of drug-loading also could be ascribed to the in situ introduction of drugs during the synthetic process. The strategy proposed in this work will bring more possibilities for the preparation of advanced functional materials based on the combination of mesoporous structure and metallic materials.

  2. Silica particles and method of preparation thereof

    NARCIS (Netherlands)

    2015-01-01

    The invention is in the field of silica products. More in particular, the invention is in the field of amorphous silica particles. The invention is directed to amorphous silica particles and related products including clusters of said silica particles, a suspension of said silica particles, and an

  3. Serpentinization processes: Influence of silica

    Science.gov (United States)

    Huang, R.; Sun, W.; Ding, X.; Song, M.; Zhan, W.

    2016-12-01

    Serpentinization systems are highly enriched in molecular hydrogen (H2) and hydrocarbons (e.g. methane, ethane and propane). The production of hydrocarbons results from reactions between H2 and oxidized carbon (carbon dioxide and carbon monoxide), which possibly contribute to climate changes during early history of the Earth. However, the influence of silica on the production of H2 and hydrocarbons was poorly constrained. We performed experiments at 311-500 °C and 3.0 kbar using mechanical mixtures of silica and olivine in ratios ranging from 0 to 40%. Molecular hydrogen (H2), methane, ethane and propane were formed, which were analyzed by gas chromatography. It was found that silica largely decreased H2 production. Without any silica, olivine serpentinization produced 94.5 mmol/kg H2 after 20 days of reaction time. By contrast, with the presence of 20% silica, H2 concentrations decreased largely, 8.5 mmol/kg. However, the influence of silica on the production of hydrocarbons is negligible. Moreover, with the addition of 20%-40% silica, the major hydrous minerals are talc, which was quantified according to an established standard curve calibrated by infrared spectroscopy analyses. It shows that silica greatly enhances olivine hydration, especially at 500 °C. Without any addition of silica, reaction extents were serpentinization at 500 °C and 3.0 kbar. By contrast, with the presence of 50% silica, olivine was completely transformed to talc within 9 days. This study indicates that silica impedes the oxidation of ferrous iron into ferric iron, and that rates of olivine hydration in natural geological settings are much faster with silica supply.

  4. FTIR and morphology of liquid epoxidized natural rubber acrylate (LENRA)/silica hybrid composites

    International Nuclear Information System (INIS)

    Eda Yuhana Ariffin; Azizan Ahmad; Dahlan Mohd; Mahathir Mohamed

    2009-01-01

    Synthesis of organic-inorganic hybrid composites was carried out by combination of liquid epoxidized natural rubber acrylate (LENRA) and silica. Silica was introduce to the matrix by sol gel technique. The sol-gel technique was employed to prepare silica using tetraethyorthosilicate (TEOS) as precursor. HDDA and irga cure 184 were added to the formulations as reactive diluents and photosensitizer, respectively. The chemical modification was studied by Fourier Transform Infrared (FTIR) and energy dispersive X-ray analysis (EDAX). The morphological studies were conducted by the optical and scanning electron microscopes (SEM). It shows that silica was dispersed very well in the matrix for lower concentration of TEOS while agglomeration occurs at the higher concentration. The average particles size of silica were less than 100 nm. (Author)

  5. Miniature all-silica optical fiber pressure sensor with an ultrathin uniform diaphragm.

    Science.gov (United States)

    Wang, Wenhui; Wu, Nan; Tian, Ye; Niezrecki, Christopher; Wang, Xingwei

    2010-04-26

    This paper presents an all-silica miniature optical fiber pressure/acoustic sensor based on the Fabry-Perot (FP) interferometric principle. The endface of the etched optical fiber tip and silica thin diaphragm on it form the FP structure. The uniform and thin silica diaphragm was fabricated by etching away the silicon substrate from a commercial silicon wafer that has a thermal oxide layer. The thin film was directly thermally bonded to the endface of the optical fiber thus creating the Fabry-Perot cavity. Thin films with a thickness from 1microm to 3microm have been bonded successfully. The sensor shows good linearity and hysteresis during measurement. A sensor with 0.75 microm-thick diaphragm thinned by post silica etching was demonstrated to have a sensitivity of 11 nm/kPa. The new sensor has great potential to be used as a non-intrusive pressure sensor in a variety of sensing applications.

  6. Silica coated ionic liquid templated mesoporous silica nanoparticles ...

    African Journals Online (AJOL)

    A series of long chain pyridinium based ionic liquids 1-tetradecylpyridinium bromide, 1-hexadecylpyridinium bromide and 1-1-octadecylpyridinium bromide were used as templates to prepare silica coated mesoporous silica nanoparticles via condensation method under basic condition. The effects of alkyl chain length on ...

  7. Hydrothermal stability of microporous silica and niobia-silica membranes

    NARCIS (Netherlands)

    Boffa, V.; Blank, David H.A.; ten Elshof, Johan E.

    2008-01-01

    The hydrothermal stability of microporous niobia–silica membranes was investigated and compared with silica membranes. The membranes were exposed to hydrothermal conditions at 150 and 200 °C for 70 h. The change of pore structure before and after exposure to steam was probed by single-gas permeation

  8. Ordered nanoporous silica as carriers for improved delivery of water insoluble drugs: a comparative study between three dimensional and two dimensional macroporous silica

    Directory of Open Access Journals (Sweden)

    Wang Y

    2013-10-01

    Full Text Available Ying Wang, Qinfu Zhao, Yanchen Hu, Lizhang Sun, Ling Bai, Tongying Jiang, Siling WangDepartment of Pharmaceutics, Shenyang Pharmaceutical University, Liaoning Province, People’s Republic of ChinaAbstract: The goal of the present study was to compare the drug release properties and stability of the nanoporous silica with different pore architectures as a matrix for improved delivery of poorly soluble drugs. For this purpose, three dimensional ordered macroporous (3DOM silica with 3D continuous and interconnected macropores of different sizes (200 nm and 500 nm and classic mesoporous silica (ie, Mobil Composition of Matter [MCM]-41 and Santa Barbara Amorphous [SBA]-15 with well-ordered two dimensional (2D cylindrical mesopores were successfully fabricated and then loaded with the model drug indomethacin (IMC via the solvent deposition method. Scanning electron microscopy (SEM, N2 adsorption, differential scanning calorimetry (DSC, and X-ray diffraction (XRD were applied to systematically characterize all IMC-loaded nanoporous silica formulations, evidencing the successful inclusion of IMC into nanopores, the reduced crystallinity, and finally accelerated dissolution of IMC. It was worth mentioning that, in comparison to 2D mesoporous silica, 3DOM silica displayed a more rapid release profile, which may be ascribed to the 3D interconnected pore networks and the highly accessible surface areas. The results obtained from the stability test indicated that the amorphous state of IMC entrapped in the 2D mesoporous silica (SBA-15 and MCM-41 has a better physical stability than in that of 3DOM silica. Moreover, the dissolution rate and stability of IMC loaded in 3DOM silica was closely related to the pore size of macroporous silica. The colorimetric 3-(4,5-Dimethylthiazol-2-yl-2,5-diphenyltetrazolium bromide (MTT and Cell Counting Kit (CCK-8 assays in combination with direct morphology observations demonstrated the good biocompatibility of nanoporous

  9. Study of the spectra of silica colloidal crystals with assembled silver obtained from a photolysis method

    Science.gov (United States)

    Li, Wenjiang; He, Jinglong; He, Sailing

    2005-02-01

    The colorful artificial 3D silica colloidal crystals (opal) were prepared through self-assembly of silica spheres in the visible frequency range. We directly synthesized nano silver particles in the void of the silica artificial opal film using the photolysis of silver nitrate under UV light, nano silver particles were self-deposited around the surface of silica sphere. The shifts of the stop band of the artificial crystals after exposing different time under UV light were studied. Synthetic silica opal with three-dimensional (3D) structure is potentially useful for the development of diffractive optical devices, micro mechanical systems, and sensory elements because photonic band gaps obtained from self-assembled closely packed periodic structures.

  10. Preparation and characterization of silk/silica hybrid biomaterials by sol-gel crosslinking process

    Energy Technology Data Exchange (ETDEWEB)

    Hou Aiqin, E-mail: aiqinhou@dhu.edu.c [National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, 3H, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China); Chen Huawei [National Engineering Research Center for Dyeing and Finishing of Textiles, Donghua University, 3H, 2999 North Renmin Road, Songjiang, Shanghai 201620 (China)

    2010-03-15

    The silk/silica hybrid biomaterials are synthesized by sol-gel crosslinking process. The chemical and morphological structures of silk/silica hybrids are investigated with micro-FT-IR spectra, X-ray diffraction, SEM, AFM, and DSC. The results show that the crosslinking reactions among inorganic nano-particles, fibroin and 2,4,6-tri[(2-epihydrin-3-bimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-EBAC) take place during sol-gel process. The silk/silica hybrids form new molecular structures containing not only organic fibroin but also inorganic nano-silica particles. The inorganic particles are bounded to the fibroin through covalent bonds. The silk/silica hybrids can form excellent film with very even nanometer particles. The thermal properties of organic/inorganic hybrid are improved.

  11. Preparation and characterization of silk/silica hybrid biomaterials by sol-gel crosslinking process

    International Nuclear Information System (INIS)

    Hou Aiqin; Chen Huawei

    2010-01-01

    The silk/silica hybrid biomaterials are synthesized by sol-gel crosslinking process. The chemical and morphological structures of silk/silica hybrids are investigated with micro-FT-IR spectra, X-ray diffraction, SEM, AFM, and DSC. The results show that the crosslinking reactions among inorganic nano-particles, fibroin and 2,4,6-tri[(2-epihydrin-3-bimethyl-ammonium)propyl]-1,3,5-triazine chloride (Tri-EBAC) take place during sol-gel process. The silk/silica hybrids form new molecular structures containing not only organic fibroin but also inorganic nano-silica particles. The inorganic particles are bounded to the fibroin through covalent bonds. The silk/silica hybrids can form excellent film with very even nanometer particles. The thermal properties of organic/inorganic hybrid are improved.

  12. Synthesis and properties of highly dispersed ionic silica-poly(ethylene oxide) nanohybrids.

    KAUST Repository

    Fernandes, Nikhil J

    2013-02-04

    We report an ionic hybrid based on silica nanoparticles as the anion and amine-terminated poly(ethylene oxide) (PEO) as a cation. The charge on the nanoparticle anion is carried by the surface hydroxyls. SAXS and TEM reveal an exceptional degree of dispersion of the silica in the polymer and high degree of order in both thin film and bulk forms. In addition to better dispersion, the ionic hybrid shows improved flow characteristics compared to silica/PEO mixtures in which the ionic interactions are absent.

  13. Synthesis and properties of highly dispersed ionic silica-poly(ethylene oxide) nanohybrids.

    KAUST Repository

    Fernandes, Nikhil J; Akbarzadeh, Johanna; Peterlik, Herwig; Giannelis, Emmanuel P

    2013-01-01

    We report an ionic hybrid based on silica nanoparticles as the anion and amine-terminated poly(ethylene oxide) (PEO) as a cation. The charge on the nanoparticle anion is carried by the surface hydroxyls. SAXS and TEM reveal an exceptional degree of dispersion of the silica in the polymer and high degree of order in both thin film and bulk forms. In addition to better dispersion, the ionic hybrid shows improved flow characteristics compared to silica/PEO mixtures in which the ionic interactions are absent.

  14. Pecan drying with silica gel

    Energy Technology Data Exchange (ETDEWEB)

    Ghate, S.R.; Chhinnan, M.S.

    1983-07-01

    High moisture in-shell pecans were dried by keeping them in direct and indirect contact with silica gel to investigate their drying characteristics. In-shell pecans were also dried with ambient air from a controlled environment chamber and with air dehumidified by silica gel. Direct contact and dehumidified air drying seemed feasible approaches.

  15. Hydrophobic silica nanoparticles as reinforcing filler for poly (lactic acid polymer matrix

    Directory of Open Access Journals (Sweden)

    Pilić Branka M.

    2016-01-01

    Full Text Available Properties of poly (lactic acid (PLA and its nanocomposites, with silica nanoparticles (SiO2, as filler were investigated. Neat PLA films and PLA films with different percentage of hydrophobic fumed silica nanoparticles (0.2, 0.5, 1, 2, 3 and 5 wt. % were prepared by solution casting method. Several tools were used to characterize the influence of different silica content on crystalline behavior, and thermal, mechanical and barrier properties of PLA/SiO2 nanocomposites. Results from scanning electron microscope (SEM showed that the nanocomposite preparation and selection of specific hydrophobic spherical nano filler provide a good dispersion of the silica nanoparticles in the PLA matrix. Addition of silica nanoparticles improved mechanical properties, the most significant improvement being observed for lowest silica content (0.2wt.%. Barrier properties were improved for all measured gases at all loadings of silica nanoparticles. The degree of crystallinity for PLA slightly increased by adding 0.2 and 0.5 wt. % of nano filler. [Projekat Ministarstva nauke Republike Srbije, br. III46001

  16. Oxide ultrathin films science and technology

    CERN Document Server

    Pacchioni, Gianfranco

    2012-01-01

    A wealth of information in one accessible book. Written by international experts from multidisciplinary fields, this in-depth exploration of oxide ultrathin films covers all aspects of these systems, starting with preparation and characterization, and going on to geometrical and electronic structure, as well as applications in current and future systems and devices. From the Contents: Synthesis and Preparation of Oxide Ultrathin Films Characterization Tools of Oxide Ultrathin Films Ordered Oxide Nanostructures on Metal Surfaces Unusual Properties of Oxides and Other Insulators in the Ultrathin Limit Silica and High-K Dielectrics Thin Films in Microelectronics Oxide Passive Films and Corrosion Protection Oxide Films as Catalytic Materials and as Models of Real Catalysts Oxide Films in Spintronics Oxide Ultrathin Films in Solid Oxide Fuel Cells Transparent Conducting and Chromogenic Oxide Films as Solar Energy Materials Oxide Ultrathin Films in Sensor Applications Ferroelectricity in Ultrathin Film Capacitors T...

  17. End stage renal disease among ceramic workers exposed to silica

    OpenAIRE

    Rapiti, E.; Sperati, A.; Miceli, M.; Forastiere, F.; Di, L; Cavariani, F.; Goldsmith, D. F.; Perucci, C. A.

    1999-01-01

    OBJECTIVES: To evaluate whether ceramic workers exposed to silica experience an excess of end stage renal disease. METHODS: On the basis of a health surveillance programme, a cohort of 2980 male ceramic workers has been enrolled during the period 1974-91 in Civitacastellana, Lazio, Italy. For each worker, employment history, smoking data, and x ray film readings were available. The vital status was ascertained for all cohort members. All 2820 people still alive and resident in the Lazio...

  18. SEM and Raman studies of CNT films on porous Si

    Science.gov (United States)

    Belka, R.; Keczkowska, J.; Suchańska, M.; Firek, P.; Wronka, H.; Kozłowski, M.; Radomska, J.; Czerwosz, E.; Craciunoiu, F.

    2017-08-01

    Carbon nanotube (CNT) films deposited on different porous silica substrates were studied by Scanning Electron Microscopy (SEM) and Raman Spectroscopy (RS). The films samples were prepared by a two-step method consisting of PVD and CVD processes. In the first step the nanocomposite Ni-C film was obtained by evaporation in dynamic vacuum from two separated sources of fullerenes and nickel acetate. Those films were deposited on porous silica and DLC/porous silica substrates. Analysis of SEM imaging showed that the obtained film are composed of carbon nanotubes, the distribution, size and quality of which depend on the type of substrate. The CNT films were studied by RS method to determine the influence of the substrate type on disordering of carbonaceous structure and quality of CNT in deposited films.

  19. Status of sennosides content in various Indian herbal formulations: Method standardization by HPTLC

    OpenAIRE

    Md.Wasim Aktar; Rajlakshmi Poi; Anjan Bhattacharyya

    2008-01-01

    Several poly-herbal formulations containing senna (Cassia angustifolia) leaves are available in the Indian market for the treatment of constipation. The purgative effect of senna is due to the presence of two unique hydroxy anthracene glycosides sennosides A and B. A HPTLC method for the quantitative analysis of sennosides A and B present in the formulation has been developed. Methanol extract of the formulations was analyzed on a silica gel 60 GF254 HPTLC plates with spot visualization under...

  20. Surface texture modification of spin-coated SiO2 xerogel thin films ...

    Indian Academy of Sciences (India)

    hydrolysis and condensation of tetraethylorthosilicate (TEOS) with ethanol as a solvent. Further, the deposited thin films were ... termed as hydrolysis and condensation that occur simultane- ously in the formation of silica films. ... rial leads to capillary tensions, which destroy the structure of silica (Naik and Ghosh 2009).

  1. Tetragonal zirconia quantum dots in silica matrix prepared by a modified sol-gel protocol

    Science.gov (United States)

    Verma, Surbhi; Rani, Saruchi; Kumar, Sushil

    2018-05-01

    Tetragonal zirconia quantum dots (t-ZrO2 QDs) in silica matrix with different compositions ( x)ZrO2-(100 - x)SiO2 were fabricated by a modified sol-gel protocol. Acetylacetone was added as a chelating agent to zirconium propoxide to avoid precipitation. The powders as well as thin films were given thermal treatment at 650, 875 and 1100 °C for 4 h. The silica matrix remained amorphous after thermal treatment and acted as an inert support for zirconia quantum dots. The tetragonal zirconia embedded in silica matrix transformed into monoclinic form due to thermal treatment ≥ 1100 °C. The stability of tetragonal phase of zirconia is found to enhance with increase in silica content. A homogenous dispersion of t-ZrO2 QDs in silica matrix was indicated by the mapping of Zr, Si and O elements obtained from scanning electron microscope with energy dispersive X-ray analyser. The transmission electron images confirmed the formation of tetragonal zirconia quantum dots embedded in silica. The optical band gap of zirconia QDs (3.65-5.58 eV) was found to increase with increase in zirconia content in silica. The red shift of PL emission has been exhibited with increase in zirconia content in silica.

  2. Silica research in Glasgow

    International Nuclear Information System (INIS)

    Barr, B W; Cagnoli, G; Casey, M M; Clubley, D; Crooks, D R M; Danzmann, K; Elliffe, E J; Gossler, S; Grant, A; Grote, H; Heptonstall, A; Hough, J; Jennrich, O; Lueck, H; McIntosh, S A; Newton, G P; Palmer, D A; Plissi, M V; Robertson, D I; Robertson, N A; Rowan, S; Skeldon, K D; Sneddon, P; Strain, K A; Torrie, C I; Ward, H; Willems, P A; Willke, B; Winkler, W

    2002-01-01

    The Glasgow group is involved in the construction of the GEO600 interferometer as well as in R and D activity on technology for advanced gravitational wave detectors. GEO600 will be the first GW detector using quasi-monolithic silica suspensions in order to decrease thermal noise significantly with respect to steel wire suspensions. The results concerning GEO600 suspension mounting and performance will be shown in the first section. Section 2 is devoted to the present results from the direct measurement of thermal noise in mirrors mounted in the 10 m interferometer in Glasgow which has a sensitivity limit of 4 x 10 -19 m Hz -1/2 above 1 kHz. Section 3 presents results on the measurements of coating losses. R and D activity has been carried out to understand better how thermal noise in the suspensions affects the detector sensitivity, and in section 4 a discussion on the non-linear thermoelastic effect is presented

  3. Kit systems for granulated decontamination formulations

    Science.gov (United States)

    Tucker, Mark D.

    2010-07-06

    A decontamination formulation and method of making that neutralizes the adverse health effects of both chemical and biological compounds, especially chemical warfare (CW) and biological warfare (BW) agents, and toxic industrial chemicals. The formulation provides solubilizing compounds that serve to effectively render the chemical and biological compounds, particularly CW and BW compounds, susceptible to attack, and at least one reactive compound that serves to attack (and detoxify or kill) the compound. The formulation includes at least one solubilizing agent, a reactive compound, a sorbent additive, and water. A highly adsorbent sorbent additive (e.g., amorphous silica, sorbitol, mannitol, etc.) is used to "dry out" one or more liquid ingredients into a dry, free-flowing powder that has an extended shelf life, and is more convenient to handle and mix in the field. The formulation can be pre-mixed and pre-packaged as a multi-part kit system, where one or more of the parts are packaged in a powdered, granulated form for ease of handling and mixing in the field.

  4. Characterization of electron beam deposited thin films of HfO2 and binary thin films of (HfO2:SiO2) by XRD and EXAFS measurements

    International Nuclear Information System (INIS)

    Das, N.C.; Sahoo, N.K.; Bhattacharyya, D.; Thakur, S.; Kamble, N.M.; Nanda, D.; Hazra, S.; Bal, J.K.; Lee, J.F.; Tai, Y.L.; Hsieh, C.A.

    2009-10-01

    In this report, we have discussed the microstructure and the local structure of composite thin films having varying hafnia and silica compositions and prepared by reactive electron beam evaporation. XRD and EXAFS studies have confirmed that the pure hafnium oxide thin film has crystalline microstructure whereas the films with finite hafnia and silica composition are amorphous. The result of EXAFS analysis has shown that the bond lengths as well as coordination numbers around hafnium atom change with the variation of hafnia and silica compositions in the thin film. Finally, change of bond lengths has been correlated with change of refractive index and band gap of the composite thin films. (author)

  5. A methodology for the preparation of nanoporous polyimide films with low dielectric constants

    International Nuclear Information System (INIS)

    Jiang Lizhong; Liu Jiugui; Wu Dezhen; Li Hangquan; Jin Riguang

    2006-01-01

    A method to generate nanoporous polyimide films with low dielectric constants was proposed. The preparation consisted of two steps. Firstly, a polyimide/silica hybrid film was prepared via sol-gel process. Secondly, the hybrid film was treated with hydrofluoric acid to remove the dispersed silica particles, leaving pores with diameters between 20 and 120 nm, depending on the size of silica particles. Both hybrid and porous films were subjected to a variety of characterizations including transmission electron microscopy observation, dielectric constant measurement and tensile strength measurement

  6. A study on the silica removal in primary system using the membrane process

    International Nuclear Information System (INIS)

    Kim, Bong Jin; Lee, Sang Jin; Yang, Ho Yeon; Kim, Kyung Duk; Jung, Hee Chul; Jo, Hang Rae

    2005-01-01

    Silica in primary system combines with an alkali grammatical particle metal and forms the zeolite layer which is hindering the heat transfer on the surface of the cladding. Zeolite layer becomes the cause of the damage in this way. The problems of the NPP's primary system have been issued steadily by EPRI. Through a series of experiments of the laboratory scale, we confirmed the applicability of NF membrane for silica removal, as silica rejection rate of NF membrane is about 60 ∼ 70% and boron rejection rate is about 10 ∼ 20%. We accomplished a site experiment about four NF membranes manufactured by FilmTec and Osmonics Inc. In experiment using 400L of SFP water, when operation pressure is 10kg f /cm 2 , we confirmed that the silica rejection rate of NF90-2540 manufactured by FilmTec Inc. is about 98%, boron rejection rate is about 43%. The silica rejection rate of NF270-2540 is about 38%, boron rejection rate is about 3.5%. Afterward, through additional experiments, such as long term characteristic experiments, we are going to design a optimum NF membrane system for silica removal

  7. A study on the silica removal in primary system using the membrane process

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bong Jin; Lee, Sang Jin; Yang, Ho Yeon; Kim, Kyung Duk [Korea Hydro and Nuclear Power Co., LTD., Taejeon (Korea, Republic of); Jung, Hee Chul; Jo, Hang Rae [Korea Hydro and Nuclear Power Co., LTD., Uljin (Korea, Republic of)

    2005-06-15

    Silica in primary system combines with an alkali grammatical particle metal and forms the zeolite layer which is hindering the heat transfer on the surface of the cladding. Zeolite layer becomes the cause of the damage in this way. The problems of the NPP's primary system have been issued steadily by EPRI. Through a series of experiments of the laboratory scale, we confirmed the applicability of NF membrane for silica removal, as silica rejection rate of NF membrane is about 60 {approx} 70% and boron rejection rate is about 10 {approx} 20%. We accomplished a site experiment about four NF membranes manufactured by FilmTec and Osmonics Inc. In experiment using 400L of SFP water, when operation pressure is 10kg{sub f}/cm{sup 2}, we confirmed that the silica rejection rate of NF90-2540 manufactured by FilmTec Inc. is about 98%, boron rejection rate is about 43%. The silica rejection rate of NF270-2540 is about 38%, boron rejection rate is about 3.5%. Afterward, through additional experiments, such as long term characteristic experiments, we are going to design a optimum NF membrane system for silica removal.

  8. Construction of proton exchange membranes under ultrasonic irradiation based on novel fluorine functionalizing sulfonated polybenzimidazole/cellulose/silica bionanocomposite.

    Science.gov (United States)

    Esmaielzadeh, Sheida; Ahmadizadegan, Hashem

    2018-03-01

    Novel sulfonated polybenzimidazole (s-PBI)/cellulose/silica bionanocomposite membranes were prepared from fluorine-containing s-PBI copolymer with a cellulose/silica precursor and a bonding agent. The introduction of the bonding agent results in the reinforcing interfacial interaction between s-PBI chains and the cellulose/silica nanoparticles. Commercially available silica nanoparticles were modified with biodegradable nanocellolose through ultrasonic irradiation technique. Transmission electron microscopy (TEM) analyses showed that the cellulose/silica composites were well dispersed in the s-PBI matrix on a nanometer scale. The mechanical properties and the methanol barrier ability of the s-PBI films were improved by the addition of cellulose/silica. The modulus of the s-PBI/10 wt% cellulose/silica nanocomposite membranes had a 45% increase compared to the pure s-PBI films, and the methanol permeability decreased by 62% with respect to the pure s-PBI membranes. The conductivities of the s-PBI/cellulose/silica nanocomposites were slightly lower than the pure s-PBI. The antibacterial activity of (s-PBI)/cellulose/silica was investigated against Gram-positive bacteria, ie, Staphylococcus aureus and methicillin-resistant S. aureus and Gram-negative bacteria, ie, Escherichia coli, E. coli O157:H7 and Pseudomonas aeruginosa by the disc diffusion method using Mueller Hinton agar at different sizes of cellulose/silica. All of the synthesized (s-PBI)/cellulose/silica were found to have high antibacterial activity. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. The influence of silica functionalized with silanes on migration of heavy metals in soil

    Directory of Open Access Journals (Sweden)

    Grzesiak Piotr

    2016-03-01

    Full Text Available 3-Mercaptopropyl-trimethoxysilane and [3-(2-aminoethylaminopropyl]trimethoxysilane were used to functionalize the surface of silica from Piotrowice in Poland to stabilize heavy metals (HMs and arsenic in soil. The soil for the study was sampled from the impact zone of Głogów Copper Smelter and Refinery. The soil samples were exposed to five-step Tessier sequential extraction. The speciation studies were limited to five sequentially defined fractions in which metal content was determined. The addition of unmodified silica did not affect significantly the concentration of metals in individual fractions. Significant changes were noted upon introduction of functionalized silica in the soil. The hybrid formulations obtained significantly reduce the release of heavy metals and arsenic from soil sorption complex. The results indicate the potential use of functional formulations for reduction of metal migration in soil in the areas of exceeded concentration of heavy metals and arsenic in the soil, caused by industrial activity.

  10. Silica research in Glasgow

    CERN Document Server

    Barr, B W; Casey, M M; Clubley, D; Crooks, D R M; Danzmann, K; Elliffe, E J; Gossler, S; Grant, A; Grote, H; Heptonstall, A; Hough, J; Jennrich, O; Lück, H B; McIntosh, S A; Newton, G P; Palmer, D A; Plissi, M V; Robertson, D I; Robertson, N A; Rowan, S; Skeldon, K D; Sneddon, P; Strain, K A; Torrie, C I; Ward, H; Willems, P A; Willke, B; Winkler, W

    2002-01-01

    The Glasgow group is involved in the construction of the GEO600 interferometer as well as in R and D activity on technology for advanced gravitational wave detectors. GEO600 will be the first GW detector using quasi-monolithic silica suspensions in order to decrease thermal noise significantly with respect to steel wire suspensions. The results concerning GEO600 suspension mounting and performance will be shown in the first section. Section 2 is devoted to the present results from the direct measurement of thermal noise in mirrors mounted in the 10 m interferometer in Glasgow which has a sensitivity limit of 4 x 10 sup - sup 1 sup 9 m Hz sup - sup 1 sup / sup 2 above 1 kHz. Section 3 presents results on the measurements of coating losses. R and D activity has been carried out to understand better how thermal noise in the suspensions affects the detector sensitivity, and in section 4 a discussion on the non-linear thermoelastic effect is presented.

  11. Functionalized silica aerogels for gas-phase purification, sensing, and catalysis: A review

    Energy Technology Data Exchange (ETDEWEB)

    Amonette, James E.; Matyáš, Josef

    2017-09-01

    Silica aerogels have a rich history and a unique, fascinating gas-phase chemistry that has lent them to many diverse applications. This review starts with a brief discussion of the fundamental issues driving the movement of gases in silica aerogels and then proceeds to provide an overview of the work that has been done with respect to the purification of gases, sensing of individual gases, and uses of silica aerogels as catalysts for gas-phase reactions. Salient features of the research behind these different applications are presented, and, where appropriate, critical aspects that affect the practical use of the aerogels are noted. Specific sections under the gas-purification category focus on the removal of airborne nanoparticles, carbon dioxide, volatile organic compounds, sulfur gases and radioactive iodine from gas streams. The use of silica aerogels as sensors for humidity, oxygen, hydrocarbons, volatile acids and bases, various non-ammoniacal nitrogen gases, and viral particles is discussed. With respect to catalysis, the demonstrated use of silica aerogels as supports for oxidation, Fischer-Tropsch, alkane isomerization, and hydrogenation reactions is reviewed, along with a section on untested catalytic formulations involving silica aerogels. A short section focuses on recent developments in thermomolecular Knudsen compressor pumps using silica aerogel membranes. The review continues with an overview of the production methods, locations of manufacturing facilities globally, and a brief discussion of the economics before concluding with a few remarks about the present and future trends revealed by the work presented.

  12. Silica Nanoparticles Functionalized with Zwitterionic Sulfobetaine Siloxane for Application as a Versatile Antifouling Coating System.

    Science.gov (United States)

    Knowles, Brianna R; Wagner, Pawel; Maclaughlin, Shane; Higgins, Michael J; Molino, Paul J

    2017-06-07

    The growing need to develop surfaces able to effectively resist biological fouling has resulted in the widespread investigation of nanomaterials with potential antifouling properties. However, the preparation of effective antifouling coatings is limited by the availability of reactive surface functional groups and our ability to carefully control and organize chemistries at a materials' interface. Here, we present two methods of preparing hydrophilic low-fouling surface coatings through reaction of silica-nanoparticle suspensions and predeposited silica-nanoparticle films with zwitterionic sulfobetaine (SB). Silica-nanoparticle suspensions were functionalized with SB across three pH conditions and deposited as thin films via a simple spin-coating process to generate hydrophilic antifouling coatings. In addition, coatings of predeposited silica nanoparticles were surface functionalized via exposure to zwitterionic solutions. Quartz crystal microgravimetry with dissipation monitoring was employed as a high throughput technique for monitoring and optimizing reaction to the silica-nanoparticle surfaces. Functionalization of nanoparticle films was rapid and could be achieved over a wide pH range and at low zwitterion concentrations. All functionalized particle surfaces presented a high degree of wettability and resulted in large reductions in adsorption of bovine serum albumin protein. Particle coatings also showed a reduction in adhesion of fungal spores (Epicoccum nigrum) and bacteria (Escherichia coli) by up to 87 and 96%, respectively. These results indicate the potential for functionalized nanosilicas to be further developed as versatile fouling-resistant coatings for widespread coating applications.

  13. Films Deliver: Teaching Creatively with Film.

    Science.gov (United States)

    Schillaci, Anthony, Ed.; Culkin, John M., Ed.

    The fifteen papers in this resource guide are grouped into four sections. Section one contains formulations of the basic rationale for screen education and descriptions of new concepts and approaches to film study. Section two presents a definition of the elements involved in filmmaking and viewing, and it describes several model programs which…

  14. Waste vitrification: prediction of acceptable compositions in a lime-soda-silica glass-forming system

    International Nuclear Information System (INIS)

    Gilliam, T.M.; Jantzen, C.M.

    1996-10-01

    A model is presented based upon calculated bridging oxygens which allows the prediction of the region of acceptable glass compositions for a lime-soda-silica glass-forming system containing mixed waste. The model can be used to guide glass formulation studies (e.g., treatability studies) or assess the applicability of vitrification to candidate waste streams

  15. On the role of acidity in amorphous silica-alumina based catalysts

    NARCIS (Netherlands)

    Poduval, D.G.

    2011-01-01

    Amorphous silica-alumina (ASA) is widely used as a solid acid catalyst or as a carrier for well-dispersed metal sulfide or metal catalysts. They are often involved in hydrocracking catalyst formulations, especially so when the aim is to produce middle distillates from heavy oil fractions. With

  16. Gas Separation through Bilayer Silica, the Thinnest Possible Silica Membrane.

    Science.gov (United States)

    Yao, Bowen; Mandrà, Salvatore; Curry, John O; Shaikhutdinov, Shamil; Freund, Hans-Joachim; Schrier, Joshua

    2017-12-13

    Membrane-based gas separation processes can address key challenges in energy and environment, but for many applications the permeance and selectivity of bulk membranes is insufficient for economical use. Theory and experiment indicate that permeance and selectivity can be increased by using two-dimensional materials with subnanometer pores as membranes. Motivated by experiments showing selective permeation of H 2 /CO mixtures through amorphous silica bilayers, here we perform a theoretical study of gas separation through silica bilayers. Using density functional theory calculations, we obtain geometries of crystalline free-standing silica bilayers (comprised of six-membered rings), as well as the seven-, eight-, and nine-membered rings that are observed in glassy silica bilayers, which arise due to Stone-Wales defects and vacancies. We then compute the potential energy barriers for gas passage through these various pore types for He, Ne, Ar, Kr, H 2 , N 2 , CO, and CO 2 gases, and use the data to assess their capability for selective gas separation. Our calculations indicate that crystalline bilayer silica, which is less than a nanometer thick, can be a high-selectivity and high-permeance membrane material for 3 He/ 4 He, He/natural gas, and H 2 /CO separations.

  17. Atomistic study of two-level systems in amorphous silica

    Science.gov (United States)

    Damart, T.; Rodney, D.

    2018-01-01

    Internal friction is analyzed in an atomic-scale model of amorphous silica. The potential energy landscape of more than 100 glasses is explored to identify a sample of about 700 two-level systems (TLSs). We discuss the properties of TLSs, particularly their energy asymmetry and barrier as well as their deformation potential, computed as longitudinal and transverse averages of the full deformation potential tensors. The discrete sampling is used to predict dissipation in the classical regime. Comparison with experimental data shows a better agreement with poorly relaxed thin films than well relaxed vitreous silica, as expected from the large quench rates used to produce numerical glasses. The TLSs are categorized in three types that are shown to affect dissipation in different temperature ranges. The sampling is also used to discuss critically the usual approximations employed in the literature to represent the statistical properties of TLSs.

  18. Audits of radiopharmaceutical formulations

    International Nuclear Information System (INIS)

    Castronovo, F.P. Jr.

    1992-01-01

    A procedure for auditing radiopharmaceutical formulations is described. To meet FDA guidelines regarding the quality of radiopharmaceuticals, institutional radioactive drug research committees perform audits when such drugs are formulated away from an institutional pharmacy. All principal investigators who formulate drugs outside institutional pharmacies must pass these audits before they can obtain a radiopharmaceutical investigation permit. The audit team meets with the individual who performs the formulation at the site of drug preparation to verify that drug formulations meet identity, strength, quality, and purity standards; are uniform and reproducible; and are sterile and pyrogen free. This team must contain an expert knowledgeable in the preparation of radioactive drugs; a radiopharmacist is the most qualified person for this role. Problems that have been identified by audits include lack of sterility and apyrogenicity testing, formulations that are open to the laboratory environment, failure to use pharmaceutical-grade chemicals, inadequate quality control methods or records, inadequate training of the person preparing the drug, and improper unit dose preparation. Investigational radiopharmaceutical formulations, including nonradiolabeled drugs, must be audited before they are administered to humans. A properly trained pharmacist should be a member of the audit team

  19. Pumping Iron and Silica Bodybuilding

    Science.gov (United States)

    Mcnair, H.; Brzezinski, M. A.; Krause, J. W.; Parker, C.; Brown, M.; Coale, T.; Bruland, K. W.

    2016-02-01

    The availability of dissolved iron influences the stoichiometry of nutrient uptake by diatoms. Under nutrient replete conditions diatoms consume silicic acid and nitrate in a 1:1 ratio, this ratio increases under iron stress. Using the tracers 32Si and PDMPO, the total community and group-specific silica production rates were measured along a gradient of dissolved iron in an upwelling plume off the California coast. At each station, a control (ambient silicic acid) and +20 µM silicic acid treatment were conducted with each tracer to determine whether silicic acid limitation controlled the rate of silica production. Dissolved iron was 1.3 nmol kg-1 nearshore and decreased to 0.15 nmol kg-1 offshore. Silicic acid decreased more rapidly than nitrate, it was nearly 9 µM higher in the nearshore and 7 µM lower than nitrate in the middle of the transect where the iron concentration had decreased. The rate of diatom silica production decreased in tandem with silicic acid concentration, and silica production limitation by low silicic acid was most pronounced when iron concentrations were >0.4 nmol kg-1. The composition of the diatom assemblage shifted from Chaetoceros spp. dominated nearshore to a more sparse pennate-dominated assemblage offshore. Changes in taxa-specific silica production rates will be reported based on examination of PDMPO labeled cells using confocal microscopy.

  20. Fabrication of semi-transparent super-hydrophobic surface based on silica hierarchical structures

    KAUST Repository

    Chen, Ping-Hei; Hsu, Chin-Chi; Lee, Pei-Shan; Lin, Chao-Sung

    2011-01-01

    -coating silica particles suspended in a precursor solution of silane, ethanol, and H2O with molar ratio of 1:4:4. The resulting super hydrophobic films were characterized by scanning electron microscopy (SEM), optical transmission, and contact angle measurements

  1. Amperometric xanthine biosensors using glassy carbon electrodes modified with electrografted porous silica nanomaterials loaded with xanthine oxidase

    International Nuclear Information System (INIS)

    Saadaoui, Maroua; Sánchez, Alfredo; Díez, Paula; Raouafi, Noureddine; Pingarrón, José M.; Villalonga, Reynaldo

    2016-01-01

    Glassy carbon electrodes were modified with silica materials such as silica nanoparticles, mesoporous silica nanoparticles and mesoporous silica thin films with the aim to introduce scaffolds suitable for the immobilization of enzymes. Xanthine oxidase was selected as a model enzyme, and xanthine as the target analyte. A comparison of the modified electrodes showed the biosensor prepared with mesoporous silica nanoparticles to perform best. By using the respective biosensor, xanthine can be amperometrically determined (via measurement of enzymatically formed hydrogen peroxide) at a working voltage of 0.7 V (vs. Ag/AgCl) with a 0.28 μM detection limit. The biosensor was evaluated in terms of potential interferences, reproducibility and stability, and applied to the determination of fish freshness via sensing of xanthine. (author)

  2. Reactive decontamination formulation

    Science.gov (United States)

    Giletto, Anthony [College Station, TX; White, William [College Station, TX; Cisar, Alan J [Cypress, TX; Hitchens, G Duncan [Bryan, TX; Fyffe, James [Bryan, TX

    2003-05-27

    The present invention provides a universal decontamination formulation and method for detoxifying chemical warfare agents (CWA's) and biological warfare agents (BWA's) without producing any toxic by-products, as well as, decontaminating surfaces that have come into contact with these agents. The formulation includes a sorbent material or gel, a peroxide source, a peroxide activator, and a compound containing a mixture of KHSO.sub.5, KHSO.sub.4 and K.sub.2 SO.sub.4. The formulation is self-decontaminating and once dried can easily be wiped from the surface being decontaminated. A method for decontaminating a surface exposed to chemical or biological agents is also disclosed.

  3. Dual influence of colloidal silica on skin deposition of vitamins C and E simultaneously incorporated in topical microemulsions.

    Science.gov (United States)

    Rozman, Branka; Gosenca, Mirjam; Gasperlin, Mirjana; Padois, Karine; Falson, Franciose

    2010-07-01

    Colloidal silica is the thickener of interest for topical formulations and can therefore be used to optimize the viscosity of both hydrophilic and lipophilic microemulsions (MEs). To the best of our knowledge, no information is available about the effect of topically applied colloidal silica on skin penetration of drugs. So, our aim was to determine its influence on the effectiveness of ME in the simultaneous delivery of vitamins C and E to the skin. Two different aspects of silica possible function were investigated. Its effects on formulation characteristics were studied by determination of partition coefficient of the vitamins, their solubility and release profile. The direct impact of silica on the skin was further evaluated by transepidermal water loss measurements, scanning electron microscopy (SEM), and cell toxicity determination (MTT assay). The addition of colloidal silica to ME was shown to increase significantly the vitamins' solubility and their partition to the phase in which they were less soluble. Its presence also increased the amount of both vitamins in epidermis, which was confirmed by release studies. Furthermore, we demonstrated that colloidal silica interacts with excised skin. It decreased transepidermal water loss, probably by retaining water in the stratum corneum because of its massive accumulation in the upper layers, as revealed by SEM. The results confirmed that addition of colloidal silica in ME simultaneously loaded with vitamins C and E enhanced vitamins' skin bioavailability by its dual influence on delivery characteristics of ME as well as on skin properties.

  4. Study of thin insulating films using secondary ion emission

    International Nuclear Information System (INIS)

    Hilleret, Noel

    1973-01-01

    Secondary ion emission from insulating films was investigated using a CASTAING-SLODZIAN ion analyzer. Various different aspects of the problem were studied: charge flow across a silica film; the mobilization of sodium during ion bombardment; consequences of the introduction of oxygen on the emission of secondary ions from some solids; determination of the various characteristics of secondary ion emission from silica, silicon nitride and silicon. An example of measurements made using this type of operation is presented: profiles (concentration as a function of depth) of boron introduced by diffusion or implantation in thin films of silica on silicon or silicon nitride. Such measurements have applications in microelectronics. The same method of operation was extended to other types of insulating film, and in particular, to the metallurgical study of passivation films formed on the surface of stainless steels. (author) [fr

  5. Preparation of radiopharmaceutical formulations

    International Nuclear Information System (INIS)

    Simon, J.; Garlich, J.R.; Frank, R.K.; McMillan, K.

    1998-01-01

    Radiopharmaceutical formulations for complexes comprising at least one radionuclide complexed with a ligand, or its physiologically-acceptable salts thereof, especially 153 samarium-ethylenediaminetetramethylenephosphonic acid, which optionally contains a divalent metal ion, e.g. calcium, and is frozen, thawed, and then administered by injection. Alternatively, the radiopharmaceutical formulations must contain the divalent metal and are frozen only if the time before administration is sufficiently long to cause concern for radiolysis of the ligand. 2 figs., 9 tabs

  6. Tariff formulation and equalization

    International Nuclear Information System (INIS)

    Svartsund, Trond

    2003-01-01

    The primary goal of the transmission tariff is to provide for socioeconomic use of the transmission grid. The present tariff structure is basically right. The responsibility for the formulation of the tariff resides with the local grid owner. This must take place in agreement with the current regulations which are passed by the authorities. The formulation must be adaptable to the local requirements. EBL (Norwegian Electricity Industry Association) is content with the current regulations

  7. Silica nanoparticle stability in biological media revisited.

    Science.gov (United States)

    Yang, Seon-Ah; Choi, Sungmoon; Jeon, Seon Mi; Yu, Junhua

    2018-01-09

    The stability of silica nanostructure in the core-silica shell nanomaterials is critical to understanding the activity of these nanomaterials since the exposure of core materials due to the poor stability of silica may cause misinterpretation of experiments, but unfortunately reports on the stability of silica have been inconsistent. Here, we show that luminescent silver nanodots (AgNDs) can be used to monitor the stability of silica nanostructures. Though relatively stable in water and phosphate buffered saline, silica nanoparticles are eroded by biological media, leading to the exposure of AgNDs from AgND@SiO 2 nanoparticles and the quenching of nanodot luminescence. Our results reveal that a synergistic effect of organic compounds, particularly the amino groups, accelerates the erosion. Our work indicates that silica nanostructures are vulnerable to cellular medium and it may be possible to tune the release of drug molecules from silica-based drug delivery vehicles through controlled erosion.

  8. Mesoporous silica as carrier of antioxidant for food packaging materials

    Science.gov (United States)

    Buonocore, Giovanna Giuliana; Gargiulo, Nicola; Verdolotti, Letizia; Liguori, Barbara; Lavorgna, Marino; Caputo, Domenico

    2014-05-01

    Mesoporous silicas have been long recognized as very promising materials for the preparation of drug delivery systems. In this work SBA-15 mesoporous silica has been functionalized with amino-silane to be used as carrier of antioxidant compound in the preparation of active food packaging materials exhibiting tailored release properties. Active films have been prepared by loading the antioxidant tocopherol, the purely siliceous SBA-15 and the aminofunctionalized SBA-15 loaded with tocopherol into LDPE matrix trough a two-step process (mixing+extrusion). The aim of the present work is the study of the effect of the pore size and of the chemical functionality of the internal walls of the mesophase on the migration of tocopherol from active LDPE polymer films. Moreover, it has been proved that the addition of the active compound do not worsen the properties of the film such as optical characteristic and water vapor permeability, thus leading to the development of a material which could be favorably used mainly, but not exclusively, in the sector of food packaging.

  9. Development of silica RO membranes

    International Nuclear Information System (INIS)

    Ikeda, Ayumi; Kawamoto, Takashi; Matsuyama, Emi; Utsumi, Keisuke; Nomura, Mikihiro; Sugimoto, Masaki; Yoshikawa, Masato

    2012-01-01

    Silica based membranes have been developed by using a counter diffusion CVD method. Effects of alkyl groups in the silica precursors and deposition temperatures had investigated in order to control pore sizes of the silica membranes. In this study, this type of a silica membrane was applied for RO separation. Effects of silica sources, deposition temperatures and post treatments had been investigated. Tetramethoxysilane (TMOS), Ethyltrimethoxysilane (ETMOS) and Phenyltrimethoxysilane (PhTMOS) were used as silica precursors. A counter diffusion CVD method was carried out for 90 min at 270 - 600degC on γ-alumina capillary substrates (effective length: 50 mm, φ: 4 nm: NOK Co.). O 3 or O 2 was introduced into the inside of the substrate at the O 2 rate of 0.2 L min -1 . Ion beam irradiation was carried out for a post treatment using Os at 490 MeV for 1.0 x 10 10 ions cm -2 or 3.0 x 10 10 ions cm -2 . Single gas permeance was measured by using H 2 , N 2 and SF 6 . RO tests were employed at 3.0 or 5.4 MPa for 100 mg L -1 of feed NaCl solution. First, effects of the silica sources were investigated. The total fluxes increased by increasing N 2 permeance through the silica membrane deposited by ETMOS. The maximum NaCl rejection was 28.2% at 12.2 kg m -2 h -1 of the total flux through the membrane deposited at 270degC. N 2 permeance was 9.6 x 10 -9 mol m -2 s -1 Pa -1 . While, total fluxes through the membrane deposited by using PhTMOS were smaller than those through the ETMOS membranes. The phenyl groups for the PhTMOS membrane must be important for the hydrophobic properties through the membrane. Next, effects of ion beam irradiation were tested for the TMOS membranes. Water is difficult to permeate through the TMOS membranes due to the low N 2 permeance through the membrane (3.1 x 10 -11 mol m -2 s -1 Pa -1 ). N 2 permeance increased to 7.3 x 10 -9 mol m -2 s -1 Pa -1 by the irradiation. Irradiation amounts had little effects on N 2 permeance. However, NaCl rejections

  10. [Oral films as perspective dosage form].

    Science.gov (United States)

    Walicová, Veronika; Gajdziok, Jan

    Oral films, namely buccal mucoadhesive films and orodispersible films represent innovative formulations for administration of a wide range of drugs. Oral films show many advantageous properties and are intended for systemic drug delivery or for local treatment of the oral mucosa. In both cases, the film represents a thin layer, which could be intended to adhere to the oral mucosa by means of mucoadhesion; or to rapid dissolution and subsequent swallowing without the need of liquid intake, in the case of orodispersible films. Main constitutive excipients are film-forming polymers, which must in the case of mucoadhesive forms remain on the mucosa within the required time interval. Oral films are currently available on the pharmaceutical market and could compete with conventional oral dosage forms in the future. oral cavity oral films buccal mucoadhesive films orodispersible films film-forming polymers.

  11. Niobia-silica and silica membranes for gas separation

    NARCIS (Netherlands)

    Boffa, V.

    2008-01-01

    This thesis describes the development of ceramic membranes suitable for hydrogen separation and CO2 recovery from gaseous streams. The research work was focused on the three different parts of which gas selective ceramic membranes are composed, i.e., the microporous gas selective silica layer, the

  12. Sonochemical coating of magnetite nanoparticles with silica.

    Science.gov (United States)

    Dang, Feng; Enomoto, Naoya; Hojo, Junichi; Enpuku, Keiji

    2010-01-01

    Magnetite nanoparticles were coated with silica through the hydrolysis and condensation of tetraethyl orthosilicate (TEOS) under ultrasonic irradiation. The ultrasonic irradiation was used to prevent the agglomeration of the magnetite particles and accelerate the hydrolysis and condensation of TEOS. TEM, DLS, XRF, VSM, TG and sedimentation test were used to characterize the silica-coated magnetite particles. The dispersibility of silica-coated magnetite particles in aqueous solution was improved significantly and the agglomerate particle size was decreased to 110 nm. It was found that the agglomerate particle size of silica-coated magnetite particles was mainly decided by the coating temperature and the pH value in the silica-coating process. The weight ratio of silica in silica-coated magnetite particles was mainly decided by the pH value in the silica-coating process. The dispersibility of silica-coated magnetite particles was mainly decided by the agglomerate particle size of the suspension. The oxidation of magnetite particles in air was limited through the coated silica. The magnetism of silica-coated magnetite particles decreased slightly after silica-coating.

  13. 21 CFR 584.700 - Hydrophobic silicas.

    Science.gov (United States)

    2010-04-01

    ...) Product. Amorphous fumed hydrophobic silica or precipitated hydrophobic silica (CAS Reg. No. 68611-0944... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Hydrophobic silicas. 584.700 Section 584.700 Food... DRUGS, FEEDS, AND RELATED PRODUCTS FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE IN FEED AND...

  14. Fabrication and characterization of Aerogel-Polydimethyl siloxane (PDMS) Insulation Film

    Science.gov (United States)

    Noh, Yeoung ah; Song, Sinae; Taik Kim, Hee

    2018-03-01

    The building has a large impact on the space heating demand and the indoor environment is affected by climate or daylight. Hence, silica aerogel has generally used as a film to reduce the coefficient of the window in the building. Silica aerogel is a suitable material to apply for insulation material with lower thermal conductivity than that of air to save interior energy. However expensive precursor and drying process were the main issue of the silica aerogel synthesis and practical usage. We attempt to fabricate aerogel insulation film for energy saving through the economic process under ambient pressure. Silica aerogel was synthesized from rice husk ash, which was an agricultural waste to be able to recycle. Taguchi design was used to optimize the parameters (amount of rice husk ash, pH, aging time) controlling the surface area of silica aerogel. The silica aerogel is prepared by sol-gel processing through acidic treatment and aging. The silica aerogel was obtained by modification of silica hydrogel surface and dry at ambient pressure. Finally, aerogel film was respectively fabricated by the different content of aerogel in polydimethylsiloxane (PDMS). Silica aerogel obtained 21 – 24nm average particle size was analyzed by SEM and silica aerogel with high surface area (832.26 m2/g), pore size ( 3.30nm ) was characterized by BET. Then silica Aerogel – PDMS insulation film with thermal conductivity (0.002 W/mK) was analyzed by thermal wave system. The study demonstrates an eco-friendly and low-cost route toward silica – PDMS insulation film with low thermal conductivity (0.002 W/mK).

  15. Poling of Planar Silica Waveguides

    DEFF Research Database (Denmark)

    Arentoft, Jesper; Kristensen, Martin; Jensen, Jesper Bo

    1999-01-01

    UV-written planar silica waveguides are poled using two different poling techniques, thermal poling and UV-poling. Thermal poling induces an electro-optic coefficient of 0.067 pm/V. We also demonstrate simultaneous UV-writing and UV-poling. The induced electro-optic effect shows a linear dependence...

  16. Functionalized silica materials for electrocatalysis

    Indian Academy of Sciences (India)

    To increase the efficiency of the electrocatalytic process and to increase the electrochemical accessibility of the immobilized electrocatalysts, functionalized and non-functionalized mesoporous organo-silica (MCM41-type-materials) are used in this study. These materials possess several suitable properties to be durable ...

  17. Preparation of mesoporous silica microparticles by sol-gel/emulsion route for protein release.

    Science.gov (United States)

    Vlasenkova, Mariya I; Dolinina, Ekaterina S; Parfenyuk, Elena V

    2018-04-06

    Encapsulation of therapeutic proteins into particles from appropriate material can improve both stability and delivery of the drugs, and the obtained particles can serve as a platform for development of their new oral formulations. The main goal of this work was development of sol-gel/emulsion method for preparation of silica microcapsules capable of controlled release of encapsulated protein without loss of its native structure. For this purpose, the reported in literature direct sol-gel/W/O/W emulsion method of protein encapsulation was used with some modifications, because the original method did not allow to prepare silica microcapsules capable for protein release. The particles were synthesized using sodium silicate and tetraethoxysilane as silica precursors and different compositions of oil phase. In vitro kinetics of bovine serum albumin (BSA) release in buffer (pH 7.4) was studied by Fourier transform infrared (FTIR) and fluorescence spectrometry, respectively. Structural state of encapsulated BSA and after release was evaluated. It was found that the synthesis conditions influenced substantially the porous structure of the unloaded silica particles, release properties of the BSA-loaded silica particles and structural state of the encapsulated and released protein. The modified synthesis conditions made it possible to obtain the silica particles capable of controlled release of the protein during a week without loss of the protein native structure.

  18. Synthesis of mesoporous silica nanoparticles by sol–gel as nanocontainer for future drug delivery applications

    Energy Technology Data Exchange (ETDEWEB)

    Vazquez, N.I.; Gonzalez, Z.; Ferrari, B.; Castro, Y.

    2017-07-01

    Development of mesoporous silica nanoparticles as carriers for drug delivery systems has increased exponentially during the last decade. The present work is focused on the synthesis of silica carriers by sol–gel from tetraethyl orthosilicate (TEOS) as precursor of silica and cetyltrimethylammonium bromide (CTAB) as pore generating agent. The synthesis conditions were modified varying the molar ratio of water/TEOS, NH3/TEOS and amount of CTAB. The silica particles were characterized by scan electron microscopy techniques (FESEM), high resolution transmission electron microscopy (HR-TEM), N2 adsorption–desorption isotherms, Zeta-potential and Dynamic Light Scattering (DLS). The results show that the specific surface area and the porosity of silica particles were strongly affected by the addition of CTAB and the amount of H2O. The dispersion and stability of silica mesoporous particles is achieved in spite of the high surface reactivity. The synthesis formulation affects considerably to the particle morphology, which changes from spheres to rods when the molar ratio of H2O increases. A maximum specific surface area of 1480m2/g was obtained with pore sizes ranging 2.5–2.8nm. (Author)

  19. Elaboration of colloidal silica sols in aqueous medium: functionalities, optical properties and chemical detection of coating

    International Nuclear Information System (INIS)

    Le Guevel, X.

    2006-03-01

    The aim of this work was to study surface reactivity of silica nanoparticles through physical and chemical properties of sols and coatings. Applications are numerous and they are illustrated in this work by optical coating preparation for laser components and chemical gas sensor development for nitroaromatics detection. On one hand, protocol synthesis of colloidal silica sols has been developed in water medium using sol-gel process (0 to 100 w%). These sols, so-called BLUESIL, are time-stable during at least one year. Homogeneous coatings having thickness fixed to 200 nm, have been prepared on silica substrate and show high porosity and high transparence. Original films have been developed using catalytic curing in gas atmosphere (ammonia curing) conferring good abrasive resistance to the coating without significant properties modification. In order to reduce film sensitivity to molecular adsorption (water, polluting agents... ), specific BLUESIL coatings have been prepared showing hydrophobic property due to apolar species grafting onto silica nanoparticles. Using this route, coatings having several functional properties such as transparence, hydrophobicity, high porosity and good abrasive resistance have been elaborated. On the other hand, we show that colloidal silica is a material specifically adapted to the detection of nitro aromatic vapors (NAC). Indeed, the use of colloidal silica as chemical gas sensor reveals very high sensitivity, selectivity to NAC compared to Volatile Organic Compound (V.O.C) and good detection performances during one year. Moreover, chemical sensors using functionalized colloidal silica have exhibited good results of detection, even in high humidity medium (≥70 %RH). (author)

  20. Fracture properties of hydrogenated amorphous silicon carbide thin films

    International Nuclear Information System (INIS)

    Matsuda, Y.; King, S.W.; Bielefeld, J.; Xu, J.; Dauskardt, R.H.

    2012-01-01

    The cohesive fracture properties of hydrogenated amorphous silicon carbide (a-SiC:H) thin films in moist environments are reported. Films with stoichiometric compositions (C/Si ≈ 1) exhibited a decreasing cohesive fracture energy with decreasing film density similar to other silica-based hybrid organic–inorganic films. However, lower density a-SiC:H films with non-stoichiometric compositions (C/Si ≈ 5) exhibited much higher cohesive fracture energy than the films with higher density stoichiometric compositions. One of the non-stoichiometric films exhibited fracture energy (∼9.5 J m −2 ) greater than that of dense silica glasses. The increased fracture energy was due to crack-tip plasticity, as demonstrated by significant pileup formation during nanoindentation and a fracture energy dependence on film thickness. The a-SiC:H films also exhibited a very low sensitivity to moisture-assisted cracking compared with other silica-based hybrid films. A new atomistic fracture model is presented to describe the observed moisture-assisted cracking in terms of the limited Si-O-Si suboxide bond formation that occurs in the films.

  1. Sol-gel preparation of Ag-silica nanocomposite with high electrical conductivity

    Science.gov (United States)

    Ma, Zhijun; Jiang, Yuwei; Xiao, Huisi; Jiang, Bofan; Zhang, Hao; Peng, Mingying; Dong, Guoping; Yu, Xiang; Yang, Jian

    2018-04-01

    Sol-gel derived noble-metal-silica nanocomposites are very useful in many applications. Due to relatively low price, higher conductivity, and higher chemical stability of silver (Ag) compared with copper (Cu), Ag-silica has gained much more research interest. However, it remains a significant challenge to realize high loading of Ag content in sol-gel Ag-silica composite with high structural controllability and nanoparticles' dispersity. Different from previous works by using multifunctional silicon alkoxide to anchor metal ions, here we report the synthesis of Ag-silica nanocomposite with high loading of Ag nanoparticles by employing acetonitrile bi-functionally as solvent and metal ions stabilizer. The electrical conductivity of the Ag-silica nanocomposite reached higher than 6800 S/cm. In addition, the Ag-silica nanocomposite could simultaneously possess high electrical conductivity and positive conductivity-temperature coefficient by properly controlling the loading content of Ag. Such behavior is potentially advantageous for high-temperature devices (like phosphoric acid fuel cells) and inhibiting the thermal-induced increase of devices' internal resistance. The strategy proposed here is also compatible with block-copolymer directed self-assembly of mesoporous material, spin-coating of film and electrospinning of nanofiber, making it more charming in various practical applications.

  2. Cultivation of human dermal fibroblasts and epidermal keratinocytes on keratin-coated silica bead substrates.

    Science.gov (United States)

    Tan, Bee Yi; Nguyen, Luong T H; Kim, Hyo-Sop; Kim, Jae-Ho; Ng, Kee Woei

    2017-10-01

    Human hair keratin is promising as a bioactive material platform for various biomedical applications. To explore its versatility further, human hair keratin was coated onto monolayers of silica beads to produce film-like substrates. This combination was hypothesized to provide a synergistic effect in improving the biochemical properties of the resultant composite. Atomic force microscopy analysis showed uniform coatings of keratin on the silica beads with a slight increase in the resulting surface roughness. Keratin-coated silica beads had higher surface energy and relatively lower negative charge than those of bare silica beads. To investigate cell response, human dermal fibroblasts (HDFs), and human epidermal keratinocytes (HEKs) were cultured on the substrates over 4 days. Results showed that keratin coatings significantly enhanced the metabolic activity of HDFs and encouraged cell spreading but did not exert any significant effects on HEKs. HDF expression of collagen I was significantly more intense on the keratin-coated compared to the bare silica substrates. Furthermore, HDF secretion of various cytokines suggested that keratin coatings triggered active cell responses related to wound healing. Collectively, our study demonstrated that human hair keratin-coated silica bead monolayers have the potential to modulate HDF behavior in culture and may be exploited further. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2789-2798, 2017. © 2017 Wiley Periodicals, Inc.

  3. Development of Formulations for a-SiC and Manganese CMP and Post-CMP Cleaning of Cobalt

    Science.gov (United States)

    Lagudu, Uma Rames Krishna

    . Furthermore, addition of a low concentration of 250 ppm Brij-35 to this slurry suppressed the RRs of silicon dioxide to zero, while retaining the RRs of a-SiC at ˜2700 nm/h , a combination of RRs that is appropriate for hard mask polishing. The second part of this thesis focuses on the polishing of manganese which was proposed as a "self-forming" barrier material to prevent copper diffusion in advanced generation (22 nm and smaller) Si devices. A major challenge associated with such a self-forming Mn barrier for Cu interconnects in sub-22nm devices is galvanic corrosion that can occur at the Cu-Mn interface during chemical mechanical planarization. In the present work, it was shown that an aqueous solution of sucrose, BTA and potassium periodate reduces the corrosion potential gap between Cu and Mn to ˜ 0.01 V at pH 10 while also lowering the galvanic currents significantly and hence can be an excellent candidate for a polishing slurry. We discuss the role of these reagents and the inhibiting film that can be formed at the interface of the bimetallic system in this solution. Preliminary polishing results for Cu and Mn using a silica-based slurry formulated with this solution are also presented. The third part involves the development of compositions for Post CMP cleaning of cobalt barriers in advanced generation (22 nm and smaller). The thickness of the cobalt films was found to impact the corrosion behavior of the films. Thinner films of cobalt were found be more prone to galvanic corrosion in the presence of copper. The corrosion currents were low for both Cu and Co in all the solutions tested but the galvanic currents varied significantly. It was found that while BTA was not able to suppress the galvanic corrosion between Cu and Co (2000 A) at pH 8, either 60 mM of 3 Amino 1,2,4 triazole or 30 mM of 3 Amino 5 methyl thio 1,2,4 triazole were able to suppress the galvanic corrosion between Cu and Co (2000 A) to < 0.3 micro amperes per square cm at pH 8. These compositions

  4. Etodolac Containing Topical Niosomal Gel: Formulation Development and Evaluation

    Directory of Open Access Journals (Sweden)

    Gyati Shilakari Asthana

    2016-01-01

    Full Text Available The present study aimed to investigate the delivery potential of Etodolac (ETD containing topical niosomal gel. Niosomal formulations were prepared by thin film hydration method at various ratios of cholesterol and Span 60 and were evaluated with respect to particle size, shape, entrapment efficiency, and in vitro characteristics. Dicetyl phosphate (DCP was also added in the niosomal formulation. Mean particle size of niosomal formulation was found to be in the range of 2 μm to 4 μm. Niosomal formulation N2 (1 : 1 ratio of cholesterol and surfactant displayed good entrapment efficiency (96.72%. TEM analyses showed that niosomal formulation was spherical in shape. Niosomal formulation (N2 displayed high percentage of drug release after 24 h (94.91 at (1 : 1 ratio of cholesterol : surfactant. Further selected niosomal formulation was used to formulate topical gel and was characterized with respect to its various parameters such as pH, viscosity, spreadability, ex vivo study, and in vivo potential permeation. Ex vivo study showed that niosomal gel possessed better skin permeation study than the plain topical gel. Further in vivo study revealed good inhibition of inflammation in case of topical niosomal gel than plain gel and niosomal formulation. The present study suggested that topical niosomal gel formulations provide sustained and prolonged delivery of drug.

  5. Synthesis of wrinkled mesoporous silica and its reinforcing effect for dental resin composites.

    Science.gov (United States)

    Wang, Ruili; Habib, Eric; Zhu, X X

    2017-10-01

    The aim of this work is to explore the reinforcing effect of wrinkled mesoporous silica (WMS), which should allow micromechanical resin matrix/filler interlocking in dental resin composites, and to investigate the effect of silica morphology, loading, and compositions on their mechanical properties. WMS (average diameter of 496nm) was prepared through the self-assembly method and characterized by the use of the electron microscopy, dynamic light scattering, and the N 2 adsorption-desorption measurements. The mechanical properties of resin composites containing silanized WMS and nonporous smaller silica were evaluated with a universal mechanical testing machine. Field-emission scanning electron microscopy was used to study the fracture morphology of dental composites. Resin composites including silanized silica particles (average diameter of 507nm) served as the control group. Higher filler loading of silanized WMS substantially improved the mechanical properties of the neat resin matrix, over the composites loaded with regular silanized silica particles similar in size. The impregnation of smaller secondary silica particles with diameters of 90 and 190nm, denoted respectively as Si90 and Si190, increased the filler loading of the bimodal WMS filler (WMS-Si90 or WMS-Si190) to 60wt%, and the corresponding composites exhibited better mechanical properties than the control fillers made with regular silica particles. Among all composites, the optimal WMS-Si190- filled composite (mass ratio WMS:Si190=10:90, total filler loading 60wt%) exhibited the best mechanical performance including flexural strength, flexural modulus, compressive strength and Vickers microhardness. The incorporation of WMS and its mixed bimodal fillers with smaller silica particles led to the design and formulation of dental resin composites with superior mechanical properties. Copyright © 2017 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  6. Influence of surface modified nano silica on alkyd binder before and after accelerated weathering

    DEFF Research Database (Denmark)

    Nikolic, Miroslav; Nguyen, Hiep Dinh; Daugaard, Anders Egede

    2016-01-01

    Introduction of nano fillers in exterior wood coatings is not straight forward. Influence on aging of polymer binder needs to be taken into account along with possible benefits that nano fillers can provide immediately after application. This study shows the influence of two differently modified...... hydrophobic nano silica on an alkyd binder for exterior wood coatings. One month after application, the highest strength and energy required to break the films was obtained with addition of 3% disilazane modified silica. Changes in tensile properties were accompanied with a small increase in glass transition...

  7. Planar waveguide amplifiers and laser in erbium doped silica

    DEFF Research Database (Denmark)

    Guldberg-Kjær, Søren Andreas; Kristensen, Martin

    1999-01-01

    with UV-light and that permanent Bragg-gratings can be induced. Planar waveguide lasers with integrated Bragg-gratings are manufactured and characterised. It is shown that linewidths below 125 kHz and output powers around 0.5 mW can be obtained, and that the manufactured lasers are resistant to mechanical...... lightwave circuits, as well as provide the gain medium for integrated planar waveguide lasers. The work and the obtained results are presented in this thesis: The manufacturing of silica thin films is described and it is shown that the refractive index o fthe films can be controlled by germanium co...... as well as thermal influence. A simple method for producing an array of planar waveguide lasers is presented and it is shown that the difference in output wavelength of the individual lasers can be controlled with great accuracy....

  8. Environmentally-Friendly Geopolymeric Binders Made with Silica

    Science.gov (United States)

    Erdogan, S. T.

    2013-12-01

    Portland cement (PC) is the ubiquitous binding material for constructions works. It is a big contributor to global warming and climate change since its production is responsible for 5-10 % of all anthropogenic CO2 emissions. Half of this emission arises from the calcination of calcareous raw materials and half from kiln fuel burning and cement clinker grinding. Recently there have been efforts to develop alternative binders with lower greenhouse gas emissions. One such class of binders is geopolymers, formed by activating natural or waste materials with suitable alkaline or acidic solutions. These binders use natural or industrial waste raw materials with a very low CO2 footprint from grinding of the starting materials, and some from the production of the activating chemicals. The total CO2 emissions from carefully formulated mixtures can be as low as 1/10th - 1/5th of those of PC concrete mixtures with comparable properties. While use of industrial wastes as raw materials is environmentally preferable, the variability of their chemical compositions over time renders their use difficult. Use of natural materials depletes resources but can have more consistent properties and can be more easily accepted. Silica sand is a natural material containing very high amounts of quartz. Silica fume is a very fine waste from silicon metal production that is mostly non-crystalline silica. This study describes the use of sodium hydroxide and sodium silicate solutions to yield mortars with mechanical properties comparable to those of portland cement mortars and with better chemical and thermal durability. Strength gain is slower than with PC mixtures at room temperature but adequate ultimate strength can be achieved with curing at slightly elevated temperatures in less than 24 h. The consistency of the chemical compositions of these materials and their abundance in several large, developing countries makes silica attractive for producing sustainable concretes with reduced carbon

  9. Influence of surface modified nanoilmenite/amorphous silica composite particles on the thermal stability of cold galvanizing coating

    Directory of Open Access Journals (Sweden)

    A.M. Al-Sabagh

    2018-03-01

    Full Text Available The present approach investigates the use of novel nanoilmenite/amorphous silica composite (NI/AS particles fabricated from ilmenite nanoparticles (FeTiO3 NPs and synthesized amorphous silica grains to improve thermal stability of the cold galvanizing coating. Transmission electron microscopic (TEM images demonstrated that both nanoilmenite and nanocomposite particles were of flaky-like nature and the average diameter of the particles is 20 nm. The lamellar shape of the nanocomposite and spherical nature of Zn-dust particles were illustrated by scanning electron microscopy (SEM micrographs. Different alkyd-based cold galvanizing coating formulations were modified using uniformly dispersing various amounts of the processed nanocomposite particles as a modifier to form some engineering nanocomposite coatings. Thermal stability of the nanocomposite and Zn-dust particles was determined by thermo-gravimetric analysis (TGA. From the obtained results it could be observed that the weight loss (% as a feature of the thermal stability in case of the nanocomposite particles was 2.9 compared to 85.9 for Zn-dust powder grains. Derivative thermo-gravimetric (DTG measurements were done under nitrogen atmosphere for the cured cold galvanizing coating samples heated from room temperature to 1000 °C. The obtained results revealed that the maximum decomposition temperature point in the third degradation step for 6% nanocomposite surface modified cured sample (CG-F was detected at 693 °C and was less value for unmodified conventional cold galvanizing coating (CG-A at 612 °C. The increase in thermal stability with increasing the concentration of nanocomposite particles could be mainly attributed to the interface surface interaction between the nanocomposite particles and alkyd resin matrix in which enhancing the inorganic-organic network stiffness by causing a reduction in the total free spaces and enhancement in the cross-linking density of the cured film

  10. Nanodrilling of fused silica using nanosecond laser radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lorenz, P., E-mail: pierre.lorenz@iom-leipzig.de; Zajadacz, J.; Bayer, L.; Ehrhardt, M.; Zimmer, K.

    2015-10-01

    Graphical abstract: - Highlights: • Low-fluence irradiation of 10 nm Mo on SiO{sub 2} results in the formation of Mo droplets. • High-fluence irradiation of droplets results in the formation of holes in the SiO{sub 2}. • The process allows the formation of randomly distributed and periodic holes. • The randomly distributed hole density ρ{sub h} depends on the fluence (ρ{sub h} ≤ 1.3 μm{sup −2}). • The interaction of the laser beam with Mo/SiO{sub 2} was simulated by FEM. - Abstract: The fast laser drilling of dielectric surfaces with hole diameters in the sub-μm range and a high aspect ratio is a challenge for laser methods. In this study, a novel laser structuring method for the production of randomly and periodically distributed holes in a fused silica surface will be presented using a self-assembling process. A fused silica surface was covered with a 10 nm thick magnetron-sputtered molybdenum film. The metal film was irradiated by a KrF excimer laser (wavelength λ = 248 nm, pulse duration Δt{sub p} = 25 ns) with low laser fluences (Φ < 1 J/cm{sup 2}) and the laser-induced heating resulting in a melting of the metal film and finally in a self-assembled formation of randomly distributed metal droplets due to the surface tension of the metal liquid phase using a top hat beam profile. Furthermore, the usage of a periodically modulated laser beam profile allows the fabrication of periodically distributed droplet pattern. The multi-pulse irradiation of the laser-generated metal droplets with higher laser fluences results in a stepwise evaporation of the metal and in a partial evaporation of the fused silica near the metal droplets. Finally, the laser-induced stepwise evaporation process results in a formation of cone-like holes in the fused silica surface where the resultant holes are dependent on the size of the generated metal droplets and on the laser parameters. The “drilling” process allows the fabrication of holes with a depth up to 1

  11. Silica aerogel and space astrophysics

    International Nuclear Information System (INIS)

    Koch-Miramond, L.

    1985-09-01

    Silica aerogels have been produced in large and transparent blocks for space astrophysics experiments since the beginning of the 1970's. They were used in cosmic ray experiments on board balloons by the Saclay group. A new space venture where aerogel Cerenkov radiators will play a decisive role is currently being prepared by a large collaboration of European and US Institutes. It will be part of the so-called International Solar Polar Mission (ISPM) which will explore the heliosphere over the full range of solar latitudes from the ecliptic (equatorial) plane to the magnetic poles of the sun. Comments on properties and long term behaviour of silica aerogel cerenkov radiators in space environment are given

  12. Infrared characterization of strontium titanate thin films

    International Nuclear Information System (INIS)

    Almeida, B.G.; Pietka, A.; Mendes, J.A.

    2004-01-01

    Strontium titanate thin films have been prepared at different oxygen pressures with various post-deposition annealing treatments. The films were deposited by pulsed laser ablation at room temperature on Si(0 0 1) substrates with a silica buffer layer. Infrared reflectance measurements were performed in order to determine relevant film parameters such as layer thicknesses and chemical composition. The infrared reflectance spectra were fitted by using adequate dielectric function forms for each layer. The fitting procedure provided the extraction of the dielectric functions of the strontium titanate film, the silica layer and the substrate. The as-deposited films are found to be amorphous, and their infrared spectra present peaks corresponding to modes with high damping constants. As the annealing time and temperature increases the strontium titanate layer becomes more ordered so that it can be described by its SrTiO 3 bulk mode parameters. Also, the silica layer grows along with the ordering of the strontium titanate film, due to oxidation during annealing

  13. Silica Nanofiber Combat Hemostat (SINCH)

    Science.gov (United States)

    2008-10-13

    1.5mg 0.6 65 205 High aspect ratio silica fibers (30um x 60nm) 9mg 0.63 58.9 140 Kaolin (TEG control) 0.2mg n/a 59.8 155 TiO2 high aspect ratio...high surface area to volume ratio and thus the material is difficult to handle in an uncontrolled environment. It is easily dispersed and is not easy

  14. Synthesis of poly(ethylene oxide)-silica hybrids

    International Nuclear Information System (INIS)

    Ishak Manaf

    2002-01-01

    A hybrid material incorporating silica networks in poly (ethylene oxide) was produced using the sol-gel process from solution mixtures of poly (ethylene oxide) dissolved in water and partially polymerized tetraethylorthosilicate (TEOS) with and without compatibilisation agent. These mixtures were converted into films by solvent evaporation and drying them in an air-circulating oven at 60 degree C. Depending on the alkoxysilane solution composition and several mixing parameters, different morphologies were obtained, varying from semi-interpenetrating networks of PEO within highly cross linked silica chains, to finely dispersed heterogeneous system exhibiting either co-continuous or particulate microstructure. The influence of pH, type of solvents, mixing temperatures and time, as well as the nature of compatibiliser was found to be extremely important in controlling the morphology and properties of the fine hybrid films. It was found that compatibilisation of PEO-SiO 2 hybrid system is achieved exclusively with the use of γ-glycidyloxypropyltrimethoxysilane (GOTMS) coupling agent. (Author)

  15. Film Reviews.

    Science.gov (United States)

    Lance, Larry M.; Atwater, Lynn

    1987-01-01

    Reviews four Human Sexuality films and videos. These are: "Personal Decisions" (Planned Parenthood Federation of America, 1985); "The Touch Film" (Sterling Production, 1986); "Rethinking Rape" (Film Distribution Center, 1985); "Not A Love Story" (National Film Board of Canada, 1981). (AEM)

  16. Catalytic removal of sulfur dioxide from dibenzothiophene sulfone over Mg-Al mixed oxides supported on mesoporous silica.

    Science.gov (United States)

    You, Nansuk; Kim, Min Ji; Jeong, Kwang-Eun; Jeong, Soon-Yong; Park, Young-Kwon; Jeon, Jong-Ki

    2010-05-01

    Dibenzothiophene sulfone (DBTS), one of the products of the oxidative desulfurization of heavy oil, can be removed through extraction as well as by an adsorption process. It is necessary to utilize DBTS in conjunction with catalytic cracking. An object of the present study is to provide an Mg-Al-mesoporous silica catalyst for the removal of sulfur dioxide from DBTS. The characteristics of the Mg-Al-mesoporous silica catalyst were investigated through N2 adsorption, XRD, ICP, and XRF. An Mg-Al-mesoporous silica catalyst formulated in a direct incorporation method showed higher catalytic performance compared to pure MgO during the catalytic removal of sulfur dioxide from DBTS. The higher dispersion of Mg as well as the large surface area of the Mg-Al-mesoporous silica catalyst strongly influenced the catalyst basicity in DBTS cracking.

  17. MASS BALANCE OF SILICA IN STRAW FROM THE PERSPECTIVE OF SILICA REDUCTION IN STRAW PULP

    Directory of Open Access Journals (Sweden)

    Celil Atik,

    2012-06-01

    Full Text Available The high silica content of wheat straw is an important limiting factor for straw pulping. High silica content complicates processing and black liquor recovery, wears out factory installations, and lowers paper quality. Each section of wheat straw has different cells and chemical compositions and thus different silica content. In this work, the silica content of balled straw samples were examined according to their physical components, including internodes, nodes, leaves (sheath and blade, rachis, grain, other plant bodies, and other plant spikes. Mass distribution of silica was determined by a dry ashing method. Half (50.90% of the silica comes from leaves, and its mechanical separation will reduce the silica content in wheat straw pulp significantly. Destroying silica bodies by sonication will increase the strength properties of straw pulp.

  18. Femtosecond Laser Desorption of Thin Polymer Films from a Dielectric Surface

    Directory of Open Access Journals (Sweden)

    Mercadier L.

    2013-11-01

    Full Text Available We desorb polymer films from fused silica with a femtosecond laser and characterize the results by atomic force microscopy. Our study as a function of beam geometry and energy reveals two ways of achieving spatially controlled nanodesorption.

  19. Mesoporous Silica: A Suitable Adsorbent for Amines

    Directory of Open Access Journals (Sweden)

    Abdollahzadeh-Ghom Sara

    2009-01-01

    Full Text Available Abstract Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices.

  20. Effect Of Formulating Additives On The Properties Of Ibuprofen Tablets

    African Journals Online (AJOL)

    A study of the comparative effects of different formulating additives and film coating on the properties of ibuprofen tablets was made. The tested properties were hardeness (H), friability (F), the disintegration time (D) and dissolution characteristics of ibuprofen tablets. The hardeness, friability, the hardeness friability ratio ...

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

    Science.gov (United States)

    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. Effect of sol aging time on the anti-reflective properties of silica coatings templated with phosphoric acid

    Directory of Open Access Journals (Sweden)

    Wen Wen

    Full Text Available Silica anti-reflective coatings have been prepared by a sol–gel dip-coating process using the sol containing phosphoric acid as a pore-forming template. The effect of the aging time of the sol on the anti-reflective properties has been investigated. The surface topography of the silica AR coatings has been characterized. With increasing sol aging time, more over-sized pores larger than 100 nm are formed in the silica coatings. These could act as scattering centers, scattering visible light and thereby lowering transmittance. The optimal aging time was identified as 1 day, and the corresponding silica coatings showed a maximum transmittance of 99.2%, representing an 8% increase compared to the bare glass substrate. Keywords: Thin films, Anti-reflective coatings, Aging, Dip-coating, Sol–gel preparation

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    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 + → Ag 0 ) 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. (paper)

  4. COOH-functionalisation of silica particles

    Energy Technology Data Exchange (ETDEWEB)

    Majewski, Peter, E-mail: peter.majewski@unisa.edu.au [School of Advanced Manufacturing and Mechanical Engineering, Mawson Institute, University of South Australia, Adelaide (Australia); Albrecht, Trent [Ian Wark Research Institute, University of South Australia, Adelaide (Australia); Weber, Siegfried [Department of Biotechnology, University of Applied Sciences, Mannheim (Germany)

    2011-09-01

    In this study COOH-functionalised silica is synthesised using phosphonateN-(phosphonomethyl)iminodiacetic acid (PMIDA) in an aqueous solution. The presence of PMIDA on the silica particles was verified using Fourier Transform Infrared Spectroscopy, X-ray Photoelectron Spectroscopy and titration. Experimentally, surface concentrations of COOH functional groups of up to about 3 mmol/g{sub silica} were achieved, whereas theoretical calculation of the maximum COOH functional group concentration gave about 1 mmol/g{sub silica}. The discrepancy may be caused by PMIDA multilayer formation on the particle.

  5. Cellular membrane trafficking of mesoporous silica nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Fang, I-Ju [Iowa State Univ., Ames, IA (United States)

    2012-01-01

    This dissertation mainly focuses on the investigation of the cellular membrane trafficking of mesoporous silica nanoparticles. We are interested in the study of endocytosis and exocytosis behaviors of mesoporous silica nanoparticles with desired surface functionality. The relationship between mesoporous silica nanoparticles and membrane trafficking of cells, either cancerous cells or normal cells was examined. Since mesoporous silica nanoparticles were applied in many drug delivery cases, the endocytotic efficiency of mesoporous silica nanoparticles needs to be investigated in more details in order to design the cellular drug delivery system in the controlled way. It is well known that cells can engulf some molecules outside of the cells through a receptor-ligand associated endocytosis. We are interested to determine if those biomolecules binding to cell surface receptors can be utilized on mesoporous silica nanoparticle materials to improve the uptake efficiency or govern the mechanism of endocytosis of mesoporous silica nanoparticles. Arginine-glycine-aspartate (RGD) is a small peptide recognized by cell integrin receptors and it was reported that avidin internalization was highly promoted by tumor lectin. Both RGD and avidin were linked to the surface of mesoporous silica nanoparticle materials to investigate the effect of receptor-associated biomolecule on cellular endocytosis efficiency. The effect of ligand types, ligand conformation and ligand density were discussed in Chapter 2 and 3. Furthermore, the exocytosis of mesoporous silica nanoparticles is very attractive for biological applications. The cellular protein sequestration study of mesoporous silica nanoparticles was examined for further information of the intracellular pathway of endocytosed mesoporous silica nanoparticle materials. The surface functionality of mesoporous silica nanoparticle materials demonstrated selectivity among the materials and cancer and normal cell lines. We aimed to determine

  6. Practical Hydrogen Loading of Air Silica Fibres

    DEFF Research Database (Denmark)

    Sørensen, Henrik Rokkjær; Jensen, Jesper Bevensee; Jensen, Jesper Bo Damm

    2005-01-01

    A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown.......A method for hydrogen-loading air-silica optical fibres has been developed allowing out-diffusion times comparable to standard step-index fibres. Examples of the first grating written in Ge-doped air-silica fibres using a 266nm UV-laser are shown....

  7. Systematic Equation Formulation

    DEFF Research Database (Denmark)

    Lindberg, Erik

    2007-01-01

    A tutorial giving a very simple introduction to the set-up of the equations used as a model for an electrical/electronic circuit. The aim is to find a method which is as simple and general as possible with respect to implementation in a computer program. The “Modified Nodal Approach”, MNA, and th......, and the “Controlled Source Approach”, CSA, for systematic equation formulation are investigated. It is suggested that the kernel of the P Spice program based on MNA is reprogrammed....

  8. Drug delivery and formulations.

    Science.gov (United States)

    Breitkreutz, Jörg; Boos, Joachim

    2011-01-01

    Paediatric drug delivery is a major challenge in drug development. Because of the heterogeneous nature of the patient group, ranging from newborns to adolescents, there is a need to use appropriate excipients, drug dosage forms and delivery devices for different age groups. So far, there is a lack of suitable and safe drug formulations for children, especially for the very young and seriously ill patients. The new EU legislation will enforce paediatric clinical trials and drug development. Current advances in paediatric drug delivery include interesting new concepts such as fast-dissolving drug formulations, including orodispersible tablets and oral thin strips (buccal wafers), and multiparticulate dosage forms based on mini-tabletting or pelletization technologies. Parenteral administration is likely to remain the first choice for children in the neonatal period and for emergency cases. Alternative routes of administration include transdermal, pulmonary and nasal drug delivery systems. A few products are already available on the market, but others still need further investigations and clinical proof of concept.

  9. Ether formulations of relativity

    International Nuclear Information System (INIS)

    Duffy, M.C.

    1980-01-01

    Contemporary ether theories are surveyed and criticised, especially those formally identical to orthodox Relativity. The historical development of Relativity, Special and General, in terms of an ether, is briefly indicated. Classical interpretations of Generalized Relativity using ether are compared to Euclidean formulations using a background space. The history of a sub-group of theories, formulating a 'new' Relativity involving modified transforms, is outlined. According to the theory with which they agree, recent supposed detections of drift are classified and criticised. Cosmological evidence suggesting an ether is mentioned. Only ether theories formally identical to Relativity have been published in depth. They stand criticised as being contrary to the positivist spirit. The history of mechanical analogues is traced, from Hartley's representing gravitating matter as spherical standing waves, to recent suggestions that vortex-sponge might model electromagnetic, quantum, uncertainty and faster-than-light phenomena. Contemporary theories are particular physical theories, themselves 'second interpretations' of a primary mathematical model. Mechanical analogues are auxiliary, not necessary, to other theory, disclosing relationships between classical and non-classical descriptions of assemblies charging state. The ether-relativity polemic, part of a broader dispute about relativity, is founded on mistaken conceptions of the roles of mathematical and physical models, mechanical analogues; and a distored view of history, which indicates that ether theories have become relativistic. (author)

  10. Synthesis of uniform carbon at silica nanocables and luminescent silica nanotubes with well controlled inner diameters

    International Nuclear Information System (INIS)

    Qian Haisheng; Yu Shuhong; Ren Lei; Yang Yipeng; Zhang Wei

    2006-01-01

    Uniform carbon at silica nanocables and silica nanotubes with well-controlled inner diameters can be synthesized in an easy way by a sacrificial templating method. This was performed using carbon nanofibres as hard templates that were synthesized previously by a hydrothermal carbonization process. Silica nanotubes with well-controlled inner diameters were synthesized from carbon at silica core-shell nanostructures by removal of the core carbon component. The inner diameters of the as-prepared silica nanotubes can be well controlled from several nanometres to hundreds of nanometres by adjusting the diameters of the carbon nanofibres. The silica nanotubes synthesized by this method display strong photoluminescence in ultraviolet at room temperature. Such uniform silica nanotubes might find potential applications in many fields such as encapsulation, catalysis, chemical/biological separation, and sensing

  11. Silica gel matrix immobilized Chlorophyta hydrodictyon africanum ...

    African Journals Online (AJOL)

    Chlorophyta hydrodictyon africanum was immobilized on a silica gel matrix to improve its mechanical properties. The algae-silica gel adsorbent was used for batch sorption studies of a cationic dye, methylene blue (MB). Optimum adsorption was obtained with a dosage of 0.8 g bio sorbent. Results from sorption studies ...

  12. Nanoporous silica membranes with high hydrothermal stability

    DEFF Research Database (Denmark)

    Boffa, Vittorio; Magnacca, Giualiana; Yue, Yuanzheng

    to improve the stability of nanoporous silica structure. This work is a quantitative study on the impact of type and concentration of transition metal ions on the microporous structure and stability of amorphous silica-based membranes, which provides information on how to design chemical compositions...

  13. Biomimetic silica encapsultation of living cells

    Science.gov (United States)

    Jaroch, David Benjamin

    Living cells perform complex chemical processes on size and time scales that artificial systems cannot match. Cells respond dynamically to their environment, acting as biological sensors, factories, and drug delivery devices. To facilitate the use of living systems in engineered constructs, we have developed several new approaches to create stable protective microenvironments by forming bioinspired cell-membrane-specific silica-based encapsulants. These include vapor phase deposition of silica gels, use of endogenous membrane proteins and polysaccharides as a site for silica nucleation and polycondensation in a saturated environment, and protein templated ordered silica shell formation. We demonstrate silica layer formation at the surface of pluripotent stem-like cells, bacterial biofilms, and primary murine and human pancreatic islets. Materials are characterized by AFM, SEM and EDS. Viability assays confirm cell survival, and metabolite flux measurements demonstrate normal function and no major diffusion limitations. Real time PCR mRNA analysis indicates encapsulated islets express normal levels of genetic markers for β-cells and insulin production. The silica glass encapsulant produces a secondary bone like calcium phosphate mineral layer upon exposure to media. Such bioactive materials can improve device integration with surrounding tissue upon implantation. Given the favorable insulin response, bioactivity, and long-term viability observed in silica-coated islets, we are currently testing the encapsulant's ability to prevent immune system recognition of foreign transplants for the treatment of diabetes. Such hybrid silica-cellular constructs have a wide range of industrial, environmental, and medical applications.

  14. Chemical immobilisation of humic acid on silica

    NARCIS (Netherlands)

    Koopal, L.K.; Yang, Y.; Minnaard, A.J.; Theunissen, P.L.M.; Riemsdijk, W.H. van

    1998-01-01

    Immobilisation of purified Aldrich humic acid (PAHA) on aminopropyl silica and glutaraldehyde-activated aminopropyl silica has been investigated. In general the humic acid is bound to the solid by both physical and chemical bonds. The physically adsorbed HA can be released to a large extent at high

  15. Refractive index dispersion law of silica aerogel

    International Nuclear Information System (INIS)

    Bellunato, T.; Calvi, M.; Matteuzzi, C.; Musy, M.; Perego, D.L.; Storaci, B.

    2007-01-01

    This paper presents measurements of the refractive index of a hygroscopic silica aerogel block at several wavelengths. The measurements, performed with a monochromator, have been compared with different parameterisations for n(λ), in order to determine the best chromaticity law for the aerogel. This is an important input for design and operation of RICH detectors with silica aerogel radiator. (orig.)

  16. Magnetic core-shell silica particles

    NARCIS (Netherlands)

    Claesson, E.M.

    2007-01-01

    This thesis deals with magnetic silica core-shell colloids and related functionalized silica structures. Synthesis routes have been developed and optimized. The physical properties of these colloids have been investigated, such as the magnetic dipole moment, dipolar structure formation and

  17. The Pozzolanic reaction of silica fume

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    2012-01-01

    Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone. In the ......Silica fume is a very important supplementary cementitious binder in High-Performance and Ultra High-Performance Concretes. Through its pozzolanic reaction the silica fume densifies the concrete micro-structure, in particular it strengthens the paste-aggregate interfacial transition zone....... In the present paper different aspects of the pozzolanic reaction of silica fume are investigated. These include chemical shrinkage, isothermal heat development and strength development. Key data for these are given and compared with theoretical calculations, and based on presented measurements the energy...

  18. Easy approach to assembling a biomimetic color film with tunable structural colors.

    Science.gov (United States)

    Wang, Wentao; Tang, Bingtao; Ma, Wei; Zhang, Jian; Ju, Benzhi; Zhang, Shufen

    2015-06-01

    The self-assembly of silica microspheres into a close-packed array is a simple method of fabricating three-dimensional photonic crystal structural color films. However, the color is very dull because of the interferences of scattering and background light. In this study, we added a small quantity of surface-modified carbon black (CB) to the system of colloidal silica in n-propanol. The use of n-propanol as a dispersant is beneficial to the rapid development of photonic crystal films during the process of dip-coating. The doping of CB into silica microspheres can absorb background and scattering light, resulting in vivid structural colors.

  19. 78 FR 14540 - Cyromazine, Silica Silicates (Silica Dioxide and Silica Gel), Glufosinate Ammonium, Dioctyl...

    Science.gov (United States)

    2013-03-06

    ... variety of agricultural food crop as well as non-food uses such as landscape and greenhouse ornamentals... film covering their bodies which normally prevents the loss of water, leading to death by desiccation...

  20. A new non-destructive and standardless method for the determination of thin films by XRF measurement

    International Nuclear Information System (INIS)

    Gries, W.H.; Wybenga, F.T.

    1981-01-01

    The thickness of thin uniform films can be determined by measuring the signal ratio of a fluorescent line at two different take-off angles and using the result in either of two mathematical relationships which link the ratio to the film thickness. A zinc sulphide film on silica is used as an example for application of this method

  1. Vozy formule 1

    OpenAIRE

    Zbožínek, Adam

    2009-01-01

    Tato práce uvádí základní pravidla a předpoklady pro konstrukci a použití vozů formule 1. Hlavní zaměření je na aerodynamiku, která je nejdůležitější disciplínou v tomto motoristickém sportu, dále je tato práce zaměřena na základní faktory týkající se motoru vozu, kol, nové technologie KERS a provedení volantu. This work shows basic rules and conditions for construction and use of cars formula 1. The main part of this work focus on the aerodynamics which is the most important discipline of...

  2. Assessment of strategy formulation

    DEFF Research Database (Denmark)

    Acur, Nuran; Englyst, Linda

    2006-01-01

    of the success criteria through face-to-face interviews with 46 managers, workshops involving 40 managers, and two in-depth case studies. The success criteria have been slightly modified due to the empirical results, to yield the assessment tool. Findings – The resulting assessment tool integrates three generic...... approaches to strategy assessment, namely the goal-centred, comparative and improvement approaches, as found in the literature. Furthermore, it encompasses three phases of strategy formulation processes: strategic thinking, strategic planning and embedding of strategy. The tool reflects that the different......, but cases and managerial perceptions indicate that the need for accurate and detailed plans might be overrated in the literature, as implementation relies heavily on continuous improvement and empowerment. Concerning embedding, key aspects relate both to the goal-centred and improvement approaches, while...

  3. Growth of ZnO nanocrystals in silica by rf co-sputter deposition and post-annealing

    International Nuclear Information System (INIS)

    Siva Kumar, V.V.; Singh, F.; Kumar, Amit; Avasthi, D.K.

    2006-01-01

    Thin films with ZnO nanocrystals in silica were synthesized by rf reactive magnetron co-sputter deposition and post-annealing. The films were deposited from a ZnO/Si composite target in an rf oxygen plasma. The deposited films were annealed in air/vacuum at high temperatures to grow ZnO nanocrystals. The deposited and annealed films were characterized by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), uv-vis spectroscopy (UV-VIS) and photoluminescence (PL) measurements. FT-IR results of the films show the vibrational features of Si-O-Si and Zn-O bonds. UV-VIS spectra of the deposited film shows the band edge of ZnO. The XRD results of the films annealed at 750 deg. C and 1000 deg. C indicate the growth of ZnO nanocrystals with average crystallite sizes between 7 nm and 26 nm. PL measurements of the deposited film show a broad visible luminescence peak which can be due to ZnO. These results suggest the growth of ZnO nanocrystals in silica matrix

  4. Radiosensitizing Silica Nanoparticles Encapsulating Docetaxel for Treatment of Prostate Cancer.

    Science.gov (United States)

    Belz, Jodi; Castilla-Ojo, Noelle; Sridhar, Srinivas; Kumar, Rajiv

    2017-01-01

    The applications of nanoparticles in oncology include enhanced drug delivery, efficient tumor targeting, treatment monitoring, and diagnostics. The "theranostic properties" associated with nanoparticles have shown enhanced delivery of chemotherapeutic drugs with superior imaging capabilities and minimal toxicities. In conventional chemotherapy, only a fraction of the administered drug reaches the tumor site or cancer cells. For successful translation of these formulations, it is imperative to evaluate the design and properties of these nanoparticles. Here, we describe the design of ultra-small silica nanoparticles to encapsulate a radiosensitizing drug for combined chemoradiation therapy. The small size of nanoparticles allows for better dispersion and uptake of the drug within the highly vascularized tumor tissue. Silica nanoparticles are synthesized using an oil-in-water microemulsion method. The microemulsion method provides a robust synthetic route in which the inner hydrophobic core is used to encapsulate chemotherapy drug, docetaxel while the outer hydrophilic region provides dispersibility of the synthesized nanoparticles in an aqueous environment. Docetaxel is commonly used for treatment of resistant or metastatic prostate cancer, and is known to have radiosensitizing properties. Here, we describe a systematic approach for synthesizing these theranostic nanoparticles for application in prostate cancer.

  5. Polymer-Silica Nanocomposites: A Versatile Platform for Multifunctional Materials

    Science.gov (United States)

    Chiu, Chi-Kai

    was ground into two different sizes of powder followed by powder pressing, heat-treating and etching. A new robust porous silver foam was then successfully made. By combining the results from room temperature and high temperature processes, we further study the patterned silver nanoparticles arrays in order to examine how mobility of silver can be controlled on a quantifiable scale. Furthermore, we have identified a thiolcontaining sol-gel precursor to control the affinity between silver and silica matrix. Lastly, the effects of interfacial interactions between sol-gel silica and other nanocomposite components and the effect of thickness of the sol-gel layer on mechanical properties were investigated. These studies were applied to the biomimetic hydroxyapatite-gelatin system. We have found that by limiting the thickness while maintaining interfacial interactions of the sol-gel layer, a unique moldable property and short hardening time from these nanocomposites can be achieved without compromising its biocompatibility. Their biocompatibility has been proven based on the in vitro and in vivo testing of these materials. In conclusion, the present study has demonstrated that polymer-silica nanocomposite is a versatile platform to carry out applications in nanocrystal growth, nanoporous metals, metal-ceramic composites, nano-imprint thin film, and bone grafts. These important findings not only provide new insights into nanocomposites but also give new meanings to the previously functional-limited sol-gel materials.

  6. Stability of anti-reflection coatings via the self-assembly encapsulation of silica nanoparticles by diazo-resins

    Science.gov (United States)

    Metzman, Jonathan S.; Ridley, Jason I.; Khalifa, Moataz B.; Heflin, James R.

    2015-12-01

    A modified silica nanoparticle (MSNP) solution was formed by the encapsulation of negatively charged silica nanoparticles by the UV-crosslinkable polycation oligomer diazo-resin (DAR). Appropriate DAR encapsulation concentrations were determined by use of zeta-potential and dynamic light scattering measurements. The MSNPs were used in conjunction with poly(styrene sulfonate) (PSS) to grow homogenous ionic self-assembled multilayer anti-reflection coatings. Stability was induced within the films by the exposure of UV-irradiation that allowed for crosslinking of the DAR and PSS. The films were characterized by UV/vis/IR spectroscopy and field emission scanning electron microscopy. The transmission and reflection levels were >98.5% and <0.05%, respectively. The refractive indices resided in the 1.25-1.26 range. The solvent stability was tested by sonication of the films in a ternary solvent (H2O/DMF/ZnCl2 3:5:2 w/w/w).

  7. Silica and lung cancer: a controversial issue.

    Science.gov (United States)

    Pairon, J C; Brochard, P; Jaurand, M C; Bignon, J

    1991-06-01

    The role of crystalline silica in lung cancer has long been the subject of controversy. In this article, we review the main experimental and epidemiological studies dealing with this problem. Some evidence for a genotoxic potential of crystalline silica has been obtained in the rare in vitro studies published to date. In vivo studies have shown that crystalline silica is carcinogenic in the rat; the tumour types appear to vary according to the route of administration. In addition, an association between carcinogenic and fibrogenic potency has been observed in various animal species exposed to crystalline silica. An excess of lung cancer related to occupational exposure to crystalline silica is reported in many epidemiological studies, regardless of the presence of silicosis. However, most of these studies are difficult to interpret because they do not correctly take into account associated carcinogens such as tobacco smoke and other occupational carcinogens. An excess of lung cancer is generally reported in studies based on silicosis registers. Overall, experimental and human studies suggest an association between exposure to crystalline silica and an excess of pulmonary malignancies. Although the data available are not sufficient to establish a clear-cut causal relationship in humans, an association between the onset of pneumoconiosis and pulmonary malignancies is probable. In contrast, experimental observations have given rise to a pathophysiological mechanism that might account for a putative carcinogenic potency of crystalline silica.

  8. Agmatine attenuates silica-induced pulmonary fibrosis.

    Science.gov (United States)

    El-Agamy, D S; Sharawy, M H; Ammar, E M

    2014-06-01

    There is a large body of evidence that nitric oxide (NO) formation is implicated in mediating silica-induced pulmonary fibrosis. As a reactive free radical, NO may not only contribute to lung parenchymal tissue injury but also has the ability to combine with superoxide and form a highly reactive toxic species peroxynitrite that can induce extensive cellular toxicity in the lung tissues. This study aimed to explore the effect of agmatine, a known NO synthase inhibitor, on silica-induced pulmonary fibrosis in rats. Male Sprague Dawley rats were treated with agmatine for 60 days following a single intranasal instillation of silica suspension (50 mg in 0.1 ml saline/rat). The results revealed that agmatine attenuated silica-induced lung inflammation as it decreased the lung wet/dry weight ratio, protein concentration, and the accumulation of the inflammatory cells in the bronchoalveolar lavage fluid. Agmatine showed antifibrotic activity as it decreased total hydroxyproline content of the lung and reduced silica-mediated lung inflammation and fibrosis in lung histopathological specimen. In addition, agmatine significantly increased superoxide dismutase (p Agmatine also reduced silica-induced overproduction of pulmonary nitrite/nitrate as well as tumor necrosis factor α. Collectively, these results demonstrate the protective effects of agmatine against the silica-induced lung fibrosis that may be attributed to its ability to counteract the NO production, lipid peroxidation, and regulate cytokine effects. © The Author(s) 2014.

  9. Optically transparent, superhydrophobic methyltrimethoxysilane based silica coatings without silylating reagent

    International Nuclear Information System (INIS)

    Kavale, Mahendra S.; Mahadik, D.B.; Parale, V.G.; Wagh, P.B.; Gupta, Satish C.; Rao, A.Venkateswara; Barshilia, Harish C.

    2011-01-01

    The superhydrophobic surfaces have drawn lot of interest, in both academic and industries because of optically transparent, adherent and self-cleaning behavior. Surface chemical composition and morphology plays an important role in determining the superhydrophobic nature of coating surface. Such concert of non-wettability can be achieved, using surface modifying reagents or co-precursor method in sol-gel process. Attempts have been made to increase the hydrophobicity and optical transparency of methyltrimethoxysilane (MTMS) based silica coatings using polymethylmethacrylate (PMMA) instead of formal routes like surface modification using silylating reagents. The optically transparent, superhydrophobic uniform coatings were obtained by simple dip coating method. The molar ratio of MTMS:MeOH:H 2 O was kept constant at 1:5.63:1.58, respectively with 0.5 M NH 4 F as a catalyst and the weight percent of PMMA varied from 1 to 8. The hydrophobicity of silica coatings was analyzed by FTIR and contact angle measurements. These substrates exhibited 91% optical transmittance as compared to glass and water drop contact angle as high as 171 ± 1 deg. The effect of humidity on hydrophobic nature of coating has been studied by exposing these films at relative humidity of 90% at constant temperature of 30 deg. C for a period of 45 days. The micro-structural studies carried out by transmission electron microscopy (TEM).

  10. End stage renal disease among ceramic workers exposed to silica.

    Science.gov (United States)

    Rapiti, E; Sperati, A; Miceli, M; Forastiere, F; Di Lallo, D; Cavariani, F; Goldsmith, D F; Perucci, C A

    1999-08-01

    To evaluate whether ceramic workers exposed to silica experience an excess of end stage renal disease. On the basis of a health surveillance programme, a cohort of 2980 male ceramic workers has been enrolled during the period 1974-91 in Civitacastellana, Lazio, Italy. For each worker, employment history, smoking data, and x ray film readings were available. The vital status was ascertained for all cohort members. All 2820 people still alive and resident in the Lazio region as in June 1994 were searched for a match in the regional end stage renal diseases registry, which records (since June, 1994) all patients undergoing dialysis treatment in public and private facilities of the region. Expected numbers of prevalent cases from the cohort were computed by applying the rate of patients on dialysis treatment by the age distribution of the cohort. A total of six cases was detected when 1.87 were expected (observed/expected (O/E) = 3.21; 95% confidence interval (95% CI) 1.17 to 6.98). The excess risk was present among non-smokers (O = 2; O/E = 4.34) and smokers (O = 4; O/E = 2.83), as well as among workers without silicosis (O = 4; O/E = 2.78) and workers with silicosis (O = 2; O/E = 4.54). The risk was higher among subjects with 20 years. These results provide further evidence that exposure to silica dust among ceramic workers is associated with nephrotoxic effects.

  11. Silica-sol-based spin-coating barrier layer against phosphorous diffusion for crystalline silicon solar cells.

    Science.gov (United States)

    Uzum, Abdullah; Fukatsu, Ken; Kanda, Hiroyuki; Kimura, Yutaka; Tanimoto, Kenji; Yoshinaga, Seiya; Jiang, Yunjian; Ishikawa, Yasuaki; Uraoka, Yukiharu; Ito, Seigo

    2014-01-01

    The phosphorus barrier layers at the doping procedure of silicon wafers were fabricated using a spin-coating method with a mixture of silica-sol and tetramethylammonium hydroxide, which can be formed at the rear surface prior to the front phosphorus spin-on-demand (SOD) diffusion and directly annealed simultaneously with the front phosphorus layer. The optimization of coating thickness was obtained by changing the applied spin-coating speed; from 2,000 to 8,000 rpm. The CZ-Si p-type silicon solar cells were fabricated with/without using the rear silica-sol layer after taking the sheet resistance measurements, SIMS analysis, and SEM measurements of the silica-sol material evaluations into consideration. For the fabrication of solar cells, a spin-coating phosphorus source was used to form the n(+) emitter and was then diffused at 930°C for 35 min. The out-gas diffusion of phosphorus could be completely prevented by spin-coated silica-sol film placed on the rear side of the wafers coated prior to the diffusion process. A roughly 2% improvement in the conversion efficiency was observed when silica-sol was utilized during the phosphorus diffusion step. These results can suggest that the silica-sol material can be an attractive candidate for low-cost and easily applicable spin-coating barrier for any masking purpose involving phosphorus diffusion.

  12. Formation of plasma induced surface damage in silica glass etching for optical waveguides

    International Nuclear Information System (INIS)

    Choi, D.Y.; Lee, J.H.; Kim, D.S.; Jung, S.T.

    2004-01-01

    Ge, B, P-doped silica glass films are widely used as optical waveguides because of their low losses and inherent compatibility with silica optical fibers. These films were etched by ICP (inductively coupled plasma) with chrome etch masks, which were patterned by reactive ion etching (RIE) using chlorine-based gases. In some cases, the etched surfaces of silica glass were very rough (root-mean square roughness greater than 100 nm) and we call this phenomenon plasma induced surface damage (PISD). Rough surface cannot be used as a platform for hybrid integration because of difficulty in alignment and bonding of active devices. PISD reduces the etch rate of glass and it is very difficult to remove residues on a rough surface. The objective of this study is to elucidate the mechanism of PISD formation. To achieve this goal, PISD formation during different etching conditions of chrome etch mask and silica glass was investigated. In most cases, PISD sources are formed on a glass surface after chrome etching, and metal compounds are identified in theses sources. Water rinse after chrome etching reduces the PISD, due to the water solubility of metal chlorides. PISD is decreased or even disappeared at high power and/or low pressure in glass etching, even if PISD sources were present on the glass surface before etching. In conclusion, PISD sources come from the chrome etching process, and polymer deposition on these sources during the silica etching cause the PISD sources to grow. In the area close to the PISD source there is a higher ion flux, which causes an increase in the etch rate, and results in the formation of a pit

  13. Sol-gel Derived Warfarin - Silica Composites for Controlled Drug Release.

    Science.gov (United States)

    Dolinina, Ekaterina S; Parfenyuk, Elena V

    2017-01-01

    Warfarin, commonly used anticoagulant in clinic, has serious shortcomings due to its unsatisfactory pharmacodynamics. One of the efficient ways for the improvement of pharmacological and consumer properties of drugs is the development of optimal drug delivery systems. The aim of this work is to synthesize novel warfarin - silica composites and to study in vitro the drug release kinetics to obtain the composites with controlled release. The composites of warfarin with unmodified (UMS) and mercaptopropyl modified silica (MPMS) were synthesized by sol-gel method. The composite formation was confirmed by FTIR spectra. The concentrations of warfarin released to media with pH 1.6, 6.8 and 7.4 were measured using UV spectroscopy. The drug release profiles from the solid composites were described by a series of kinetic models which includes zero order kinetics, first order kinetics, the modified Korsmeyer-Peppas model and Hixson-Crowell model. The synthesized sol-gel composites have different kinetic behavior in the studied media. In contrast to the warfarin composite with unmodified silica, the drug release from the composite with mercaptopropyl modified silica follows zero order kinetics for 24 h irrespective to the release medium pH due to mixed mechanism (duffusion + degradation and/or disintegration of silica matrix). The obtained results showed that warfarin - silica sol-gel composites have a potential application for the development of novel oral formulation of the drug with controlled delivery. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  14. SCC modification by use of amorphous nano-silica

    NARCIS (Netherlands)

    Quercia Bianchi, G.; Spiesz, P.R.; Hüsken, G.; Brouwers, H.J.H.

    2014-01-01

    In this study two different types of nano-silica (nS) were applied in self-compacting concrete (SCC), both having similar particle size distributions (PSD), but produced through two different processes: fumed powder silica and precipitated silica in colloidal suspension. The influence of nano-silica

  15. Anchoring selenido-carbonyl ruthenium clusters to functionalized silica xerogels

    International Nuclear Information System (INIS)

    Cauzzi, Daniele; Graiff, Claudia; Pattacini, Roberto; Predieri, Giovanni; Tiripicchio, Antonio

    2003-01-01

    Silica Xerogels containing carbonyl Ru 3 Se 2 nido clusters were prepared in three different ways. The simple dispersion of [Ru 3 (μ 3 -Se) 2 (CO) 7 (PPh 3 ) 2 ] via sol gel process produces an inhomogeneous material; by contrast, homogeneous xerogels were obtained by reaction of [Ru 3 (μ 3 -Se) 2 (CO) 8 (PPh 3 )] with functionalized xerogels containing grafted diphenylphosphine moieties and by reaction of [Ru 3 (CO) 12 ] with a xerogel containing grafted phosphine-selenide groups. The reaction between [Ru 3 (CO) 12 ] and dodecyl diphenylphosphine selenide led to the formation of four selenido carbonyl clusters, which are soluble in hydrocarbon solvents and can be deposited as thin films from their solution by slow evaporation. (author)

  16. Obtaining high purity silica from rice hulls

    Directory of Open Access Journals (Sweden)

    José da Silva Júnior

    2010-01-01

    Full Text Available Many routes for extracting silica from rice hulls are based on direct calcining. These methods, though, often produce silica contaminated with inorganic impurities. This work presents the study of a strategy for obtaining silica from rice hulls with a purity level adequate for applications in electronics. The technique is based on two leaching steps, using respectively aqua regia and Piranha solutions, which extract the organic matrix and inorganic impurities. The material was characterized by Fourier-transform infrared spectroscopy (FTIR, powder x-ray diffraction (XRD, x-ray fluorescence (XRF, scanning electron microscopy (SEM, particle size analysis by laser diffraction (LPSA and thermal analysis.

  17. Functionalized silica materials for electrocatalysis

    Indian Academy of Sciences (India)

    brane/film on the surface of the electrodes by dip or spin coating and .... electrode and a thin platinum wire as counter electrode were used for ... 3.1 Materials characterization. TFS and ... in the visible region.2,11,12,18,20 Surface plasmon res-.

  18. Baseline LAW Glass Formulation Testing

    International Nuclear Information System (INIS)

    Kruger, Albert A.; Mooers, Cavin; Bazemore, Gina; Pegg, Ian L.; Hight, Kenneth; Lai, Shan Tao; Buechele, Andrew; Rielley, Elizabeth; Gan, Hao; Muller, Isabelle S.; Cecil, Richard

    2013-01-01

    The major objective of the baseline glass formulation work was to develop and select glass formulations that are compliant with contractual and processing requirements for each of the LAW waste streams. Other objectives of the work included preparation and characterization of glasses with respect to the properties of interest, optimization of sulfate loading in the glasses, evaluation of ability to achieve waste loading limits, testing to demonstrate compatibility of glass melts with melter materials of construction, development of glass formulations to support ILAW qualification activities, and identification of glass formulation issues with respect to contract specifications and processing requirements

  19. Thick-film analysis: literature search and bibliography

    International Nuclear Information System (INIS)

    Gehman, R.W.

    1981-09-01

    A literature search was conducted to support development of in-house diagnostic testing of thick film materials for hybrid microcircuits. A background literature review covered thick film formulation, processing, structure, and performance. Important material properties and tests were identified and several test procedures were obtained. Several tests were selected for thick film diagnosis at Bendix Kansas City. 126 references

  20. Drug-loaded Cellulose Acetate and Cellulose Acetate Butyrate Films ...

    African Journals Online (AJOL)

    The purpose of this research work was to evaluate the contribution of formulation variables on release properties of matrix type ocular films containing chloramphenicol as a model drug. This study investigated the use of cellulose acetate and cellulose acetate butyrate as film-forming agents in development of ocular films.

  1. Amorphous silica from rice husk at various temperatures

    International Nuclear Information System (INIS)

    Javed, S.J.; Feroze, N.; Tajwar, S.

    2008-01-01

    Rice husk is being used as a source of energy in many heat generating system because of its high calorific value and its availability in many rice producing areas. Rice husk contains approximately 20% silica which is presented in hydrated form. This hydrated silica can be retrieved as amorphous silica under controlled thermal conditions. Uncontrolled burning of rice husk produces crystalline silica which is not reactive silica but can be used as filler in many applications. Amorphous silica is reactive silica which has better market value due to its reactive nature in process industry. The present study deals with the production of amorphous silica at various temperatures from rice husk. Various ashes were prepared in tube furnace by changing the burning temperatures for fixed time intervals and analyzed by XRD. It has been observed that for two hours calculation's of rice husk renders mostly amorphous silica at 650 degree C where as at higher temperatures crystalline silica was obtained. (author)

  2. Silica-coated flexible liposomes as a nanohybrid delivery system for enhanced oral bioavailability of curcumin

    Directory of Open Access Journals (Sweden)

    Li C

    2012-12-01

    Full Text Available Chong Li, Yan Zhang, Tingting Su, Lianlian Feng, Yingying Long, Zhangbao ChenKey Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Pharmaceutical Sciences, Southwest University, Chongqing, ChinaAbstract: We investigated flexible liposomes as a potential oral drug delivery system. However, enhanced membrane fluidity and structural deformability may necessitate liposomal surface modification when facing the harsh environment of the gastrointestinal tract. In the present study, silica-coated flexible liposomes loaded with curcumin (CUR-SLs having poor water solubility as a model drug were prepared by a thin-film method with homogenization, followed by the formation of a silica shell by the sol-gel process. We systematically investigated the physical properties, drug release behavior, pharmacodynamics, and bioavailability of CUR-SLs. CUR-SLs had a mean diameter of 157 nm and a polydispersity index of 0.14, while the apparent entrapment efficiency was 90.62%. Compared with curcumin-loaded flexible liposomes (CUR-FLs without silica-coatings, CUR-SLs had significantly higher stability against artificial gastric fluid and showed more sustained drug release in artificial intestinal fluid as determined by in vitro release assays. The bioavailability of CUR-SLs and CUR-FLs was 7.76- and 2.35-fold higher, respectively, than that of curcumin suspensions. Silica coating markedly improved the stability of flexible liposomes, and CUR-SLs exhibited a 3.31-fold increase in bioavailability compared with CUR-FLs, indicating that silica-coated flexible liposomes may be employed as a potential carrier to deliver drugs with poor water solubility via the oral route with improved bioavailability.Keywords: silica, flexible liposome, oral bioavailability, curcumin

  3. Influence of the ammonium hydroxide concentration in morphological control of meso porous silica particles

    International Nuclear Information System (INIS)

    Yoon, Sukbon; Jung, Chonghun; Yoon, Inho; Kim, Changki; Choi, Wangkyu; Moon, Jeikwon

    2012-01-01

    The discovery of new M41S meso porous silica families in 1992 extended the applications into much wider pore ranges, bringing in a new prosperous era in porous material research. The synthesis of these meso porous silicas has been mainly accomplished through a self-assembly between surfactant molecules and inorganic species under various pH conditions. Meanwhile, many studies have been conducted on the application as catalysts, adsorbents, and packing materials for separation columns due to their unique properties such as high specific surface area, large pore volume, tuneable pore size, and narrow pore size distribution. The pore sizes of these materials can be easily controlled by changing the alkyl-chain length of the surfactant used. However, the control of the morphology and the pore structure is not so common. The morphological control of these materials in particular is one of the major challenges for their industrial application. Recently, the meso porous silica materials with various shapes such as fibers, films, polyhedral particles, and spheres have been reported. In our previous study, the core-shell nanoparticles with a silica core and a meso porous shell under basic conditions were synthesized using the silica nanoparticles as a core and tetraethyl orthosilicate (TEOS)-cetyltrimethylammonium bromide (CTABr)-NH 4 OH-H 2 O-C 2 H 5 OH system. In this work, we report the synthesis of the most well known hexagonal MCM-41 among three main mesophases in the M41S families using TEOS-CTABr-NH 4 OH-H 2 O system. Also, in the control of the morphology and pore structure of the meso porous silica materials, the influence of the NH 4 OH concentration was investigated

  4. Defect studies of thin ZnO films prepared by pulsed laser deposition

    International Nuclear Information System (INIS)

    Vlček, M; Čížek, J; Procházka, I; Novotný, M; Bulíř, J; Lančok, J; Anwand, W; Brauer, G; Mosnier, J-P

    2014-01-01

    Thin ZnO films were grown by pulsed laser deposition on four different substrates: sapphire (0 0 0 1), MgO (1 0 0), fused silica and nanocrystalline synthetic diamond. Defect studies by slow positron implantation spectroscopy (SPIS) revealed significantly higher concentration of defects in the studied films when compared to a bulk ZnO single crystal. The concentration of defects in the films deposited on single crystal sapphire and MgO substrates is higher than in the films deposited on amorphous fused silica substrate and nanocrystalline synthetic diamond. Furthermore, the effect of deposition temperature on film quality was investigated in ZnO films deposited on synthetic diamond substrates. Defect studies performed by SPIS revealed that the concentration of defects firstly decreases with increasing deposition temperature, but at too high deposition temperatures it increases again. The lowest concentration of defects was found in the film deposited at 450° C.

  5. Interfacial interaction between the epoxidized natural rubber and silica in natural rubber/silica composites

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tiwen [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Jia, Zhixin, E-mail: zxjia@scut.edu.cn [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Luo, Yuanfang; Jia, Demin [College of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 (China); Peng, Zheng [Agricultural Product Processing Research Institute, Chinese Academy of Tropical Agriculture Sciences, Zhanjiang 524001 (China)

    2015-02-15

    Highlights: • Substantiate the ring open reaction between Si-OH of silica and epoxy groups of ENR. • ENR can act as a bridge between NR and silica to enhance the interfacial interaction. • As a modifier, ENR gets the potential to be used in the tread of green tire for improving the wet skid resistance apparently. - Abstract: The epoxidized natural rubber (ENR) as an interfacial modifier was used to improve the mechanical and dynamical mechanical properties of NR/silica composites. In order to reveal the interaction mechanism between ENR and silica, the ENR/Silica model compound was prepared by using an open mill and the interfacial interaction of ENR with silica was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and stress–strain testing. The results indicated that the ring-opening reaction occurs between the epoxy groups of ENR chains and Si-OH groups on the silica surfaces and the covalent bonds are formed between two phases, which can improve the dispersion of silica in the rubber matrix and enhance the interfacial combination between rubber and silica. The ring-opening reaction occurs not only in vulcanization process but also in mixing process, meanwhile, the latter seems to be more important due to the simultaneous effects of mechanical force and temperature.

  6. Effect of silica concentration on electrical conductivity of epoxy resin-carbon black-silica nanocomposites

    International Nuclear Information System (INIS)

    Zhang Wei; Blackburn, Richard S.; Dehghani-Sanij, Abbas A.

    2007-01-01

    Electrical properties of nanocomposites are determined by the conductive paths of carbon black and influenced by a 'network' of silica. With increasing content of silica, carbon black (CB) particles are optimally dispersed, contributing to the generation of a conductive network between CB particles via direct particle contact and a tunneling effect; maximum conductivity for the epoxy resin-CB-silica nanocomposite described herein occurs at a ratio of 0.6:1.0 (SiO 2 :CB). As a non-conductive component, excessive silica will prevent electron flow, giving rise to low conductivity

  7. Cathodoluminescence microcharacterization of ballen silica in impactites

    International Nuclear Information System (INIS)

    Okumura, T.; Ninagawa, K.; Toyoda, S.; Gucsik, A.; Nishido, H.

    2009-01-01

    The ballen silica shows fairly weak (faint) CL with homogeneous feature in its grain exhibiting almost same spectral pattern with two broad band peaks at around 390 and 650 nm, which might be assigned to self-trapped excitons (STE) or an intrinsic and nonbridging oxygen hole centers (NBOHC), respectively, recognized in amorphous and crystalline silica. In addition, ballen silica from Lappajaervi crater shows bright and heterogeneous CL with a broad band centered at around 410 nm, presumably attributed to [AlO 4 /M + ] 0 centers or self-trapped excitons (STE). Micro-Raman and micro-XRD analyses show that fairly homogeneous CL part is α-quartz and heterogeneous CL part is composed of α-cristobalite and α-quartz. These indicate that ballen silica could be formed in the quenching process from relatively high temperature.

  8. Anomalous enthalpy relaxation in vitreous silica

    DEFF Research Database (Denmark)

    Yue, Yuanzheng

    2015-01-01

    scans. It is known that the liquid fragility (i.e., the speed of the viscous slow-down of a supercooled liquid at its Tg during cooling) has impact on enthalpy relaxation in glass. Here, we find that vitreous silica (as a strong system) exhibits striking anomalies in both glass transition and enthalpy...... relaxation compared to fragile oxide systems. The anomalous enthalpy relaxation of vitreous silica is discovered by performing the hyperquenching-annealing-calorimetry experiments. We argue that the strong systems like vitreous silica and vitreous Germania relax in a structurally cooperative manner, whereas...... the fragile ones do in a structurally independent fashion. We discuss the origin of the anomalous enthalpy relaxation in the HQ vitreous silica....

  9. Ordered mesoporous silica materials with complicated structures

    KAUST Repository

    Han, Yu; Zhang, Daliang

    2012-01-01

    Periodically ordered mesoporous silicas constitute one of the most important branches of porous materials that are extensively employed in various chemical engineering applications including adsorption, separation and catalysis. This short review

  10. Pore-Confined Carriers and Biomolecules in Mesoporous Silica for Biomimetic Separation and Targeting

    Science.gov (United States)

    Zhou, Shanshan

    Selectively permeable biological membranes composed of lipophilic barriers inspire the design of biomimetic carrier-mediated membranes for aqueous solute separation. This work imparts selective permeability to lipid-filled pores of silica thin film composite membranes using carrier molecules that reside in the lipophilic self-assemblies. The lipids confined inside the pores of silica are proven to be a more effective barrier than bilayers formed on the porous surface through vesicle fusion, which is critical for quantifying the function of an immobilized carrier. The ability of a lipophilic carrier embedded in the lipid bilayer to reversibly bind the target solute and transport it through the membrane is demonstrated. Through the functionalization of the silica surface with enzymes, enzymatic catalysis and biomimetic separations can be combined on this nanostructured composite platform. The successful development of biomimetic nanocomposite membrane can provide for efficient dilute aqueous solute upgrading or separations using engineered carrier/catalyst/support systems. While the carrier-mediated biomimetic membranes hold great potential, fully understanding of the transport processes in composite synthetic membranes is essential for improve the membrane performance. Electrochemical impedance spectroscopy (EIS) technique is demonstrated to be a useful tool for characterizing the thin film pore accessibility. Furthermore, the effect of lipid bilayer preparation methods on the silica thin film (in the form of pore enveloping, pore filling) on ion transport is explored, as a lipid bilayer with high electrically insulation is essential for detecting activity of proteins or biomimetic carriers in the bilayer. This study provides insights for making better barriers on mesoporous support for carrier-mediated membrane separation process. Porous silica nanoparticles (pSNPs) with pore sizes appropriate for biomolecule loading are potential for encapsulating dsRNA within the

  11. Microporous Silica Based Membranes for Desalination

    Directory of Open Access Journals (Sweden)

    João C. Diniz da Costa

    2012-09-01

    Full Text Available This review provides a global overview of microporous silica based membranes for desalination via pervaporation with a focus on membrane synthesis and processing, transport mechanisms and current state of the art membrane performance. Most importantly, the recent development and novel concepts for improving the hydro-stability and separating performance of silica membranes for desalination are critically examined. Research into silica based membranes for desalination has focussed on three primary methods for improving the hydro-stability. These include incorporating carbon templates into the microporous silica both as surfactants and hybrid organic-inorganic structures and incorporation of metal oxide nanoparticles into the silica matrix. The literature examined identified that only metal oxide silica membranes have demonstrated high salt rejections under a variety of feed concentrations, reasonable fluxes and unaltered performance over long-term operation. As this is an embryonic field of research several target areas for researchers were discussed including further improvement of the membrane materials, but also regarding the necessity of integrating waste or solar heat sources into the final process design to ensure cost competitiveness with conventional reverse osmosis processes.

  12. Grassy Silica Nanoribbons and Strong Blue Luminescence

    Science.gov (United States)

    Wang, Shengping; Xie, Shuang; Huang, Guowei; Guo, Hongxuan; Cho, Yujin; Chen, Jun; Fujita, Daisuke; Xu, Mingsheng

    2016-09-01

    Silicon dioxide (SiO2) is one of the key materials in many modern technological applications such as in metal oxide semiconductor transistors, photovoltaic solar cells, pollution removal, and biomedicine. We report the accidental discovery of free-standing grassy silica nanoribbons directly grown on SiO2/Si platform which is commonly used for field-effect transistors fabrication without other precursor. We investigate the formation mechanism of this novel silica nanostructure that has not been previously documented. The silica nanoribbons are flexible and can be manipulated by electron-beam. The silica nanoribbons exhibit strong blue emission at about 467 nm, together with UV and red emissions as investigated by cathodoluminescence technique. The origins of the luminescence are attributed to various defects in the silica nanoribbons; and the intensity change of the blue emission and green emission at about 550 nm is discussed in the frame of the defect density. Our study may lead to rational design of the new silica-based materials for a wide range of applications.

  13. Mesoporous Silica from Rice Husk Ash

    Directory of Open Access Journals (Sweden)

    S.A. Mandavgane

    2010-12-01

    Full Text Available Mesoporous silica is used as a raw material in several areas: in preparation of catalysts, in inks, as aconcrete hardening accelerator, as a component of detergents and soaps, as a refractory constituent etc.Sodium silicate is produced by reacting rice hull ash (RHA with aqueous NaOH and silica is precipitatedfrom the sodium silicate by acidification. In the present work, conversion of about 90% of silica containedin RHA into sodium silicate was achieved in an open system at temperatures of about 100 °C. The resultsshowed that silica obtained from RHA is mesoporous, has a large surface area and small particle size.Rice Husk is usually mixed with coal and this mixture is used for firing boilers. The RHA therefore, usuallycontains carbon particles. Activated carbon embedded on silica has been prepared using the carbon alreadypresent in RHA. This carbon shows good adsorption capacity. ©2010 BCREC UNDIP. All rights reserved(Received: 25th April 2010, Revised: 17th June 2010, Accepted: 24th June 2010[How to Cite: V.R. Shelke, S.S. Bhagade, S.A. Mandavgane. (2010. Mesoporous Silica from Rice Husk Ash. Bulletin of Chemical Reaction Engineering and Catalysis, 5 (2: 63-67. doi:10.9767/bcrec.5.2.793.63-67

  14. Mesoporous Silica from Rice Husk Ash

    Directory of Open Access Journals (Sweden)

    V.R. Shelke

    2011-01-01

    Full Text Available Mesoporous silica is used as a raw material in several areas: in preparation of catalysts, in inks, as a concrete hardening accelerator, as a component of detergents and soaps, as a refractory constituent etc. Sodium silicate is produced by reacting rice hull ash (RHA with aqueous NaOH and silica is precipitated from the sodium silicate by acidification. In the present work, conversion of about 90% of silica contained in RHA into sodium silicate was achieved in an open system at temperatures of about 100 °C. The results showed that silica obtained from RHA is mesoporous, has a large surface area and small particle size. Rice Husk is usually mixed with coal and this mixture is used for firing boilers. The RHA therefore, usually contains carbon particles. Activated carbon embedded on silica has been prepared using the carbon already present in RHA. This carbon shows good adsorption capacity. ©2010 BCREC UNDIP. All rights reserved(Received: 25th April 2010, Revised: 17th June 2010, Accepted: 24th June 2010[How to Cite: V.R. Shelke, S.S. Bhagade, S.A. Mandavgane. (2010. Mesoporous Silica from Rice Husk Ash. Bulletin of Chemical Reaction Engineering and Catalysis, 5 (2: 63-67. doi:10.9767/bcrec.5.2.793.63-67][DOI: http://dx.doi.org/10.9767/bcrec.5.2.793.63-67

  15. Transparent conducting zinc oxide thin film prepared by off-axis rf ...

    Indian Academy of Sciences (India)

    Highly conducting and transparent ZnO : Al thin films were grown by off-axis rf magnetron sputtering on amorphous silica substrates without any post-deposition annealing. The electrical and optical properties of the films deposited at various substrate temperatures and target to substrate distances were investigated in detail ...

  16. TiO2 and SiC nanostructured films, organized CNT structures

    Indian Academy of Sciences (India)

    sized nanostructured TiO2 films through hydrolysis of titanium tetra-isopropoxide. (TTIP) [9 ... structured TiO2 as a photocatalyst is as follows [15]:. TiO2(ns) ... The deposited films were easily detached from the silica tube and subjected to. SEM.

  17. Chemical solution deposition of CaCu 3 Ti 4 O 12 thin film

    Indian Academy of Sciences (India)

    CaCu3Ti4O12 (CCTO) thin film was successfully deposited on boron doped silica substrate by chemical solution deposition and rapid thermal processing. The phase and microstructure of the deposited films were studied as a function of sintering temperature, employing X-ray diffractometry and scanning electron ...

  18. Grafting of polymer onto silica surface in the presence of γ-ray irradiated silica

    International Nuclear Information System (INIS)

    Tsuchida, A.; Yokoyama, R.; Takami, M.; Chen, J.; Ohta, M.; Tsubokawa, N.

    2002-01-01

    Complete text of publication follows. We have reported the graft polymerization of vinyl monomers initiated by surface radicals formed by the decomposition of azo and peroxide groups previously introduced onto the surface. In addition, the grafting of polymers onto carbon black has been reported by the reaction of polymer radicals with the surface. On the other hand, it is well known that the relatively stable radicals are generated on the surface by the γ-ray irradiation. In this paper, the grafting of polystyrene onto silica surface during the thermal polymerization of styrene in the presence of γ-ray irradiated silica, grafting mechanism and thermal stability of grafted polymer will be discussed. The grafting of polymers onto silica surface by irradiation of polymer-adsorbed silica was also investigated. Silica obtained from Mitsubishi Chemical Co., Japan was used after pulverization: the particle size was 0.037-0.088 mm. Irradiation was performed in Cs-137 source at room temperature. The silica was irradiated at 50 Gy with dose rate of 3.463 Gy/min. Into a polymerization tube, styrene and irradiated silica was charged and the polymerization was carried out under argon under stirring. The percentage of polystyrene grafting was determined from weight loss when polystyrene-grafted silica was heated at 600 deg C by a thermal analyzer. Untreated silica did not affect the thermal polymerization of styrene. On the contrary, the thermal polymerization of styrene was remarkably retarded in the presence of the irradiated silica at 60 deg C. Similar tendency was reported during the polymerization of vinyl monomers in the presence of carbon black. In the initial stage of the polymerization in the presence of the irradiated silica below 50 deg C, the polymerization was accelerated. During the polymerization in the presence of irradiated silica, polystyrene was grafted onto the surface: the percentage of grafting was 5-11%. The amount of polystyrene grafted onto silica

  19. Sampling silica and ferrihydrite colloids with fiberglass wicks under unsaturated conditions.

    Science.gov (United States)

    Shira, Jason M; Williams, Barbara C; Flury, Markus; Czigány, Szabolcs; Tuller, Markus

    2006-01-01

    The suitability of passive capillary samplers (PCAPS) for collection of representative colloid samples under partially saturated conditions was evaluated by investigating the transport of negatively and positively charged colloids in fiberglass wicks. A synthetic pore water solution was used to suspend silica microspheres (330 nm in diameter) and ferrihydrite (172 nm in diameter) for transport experiments on fiberglass wicks. Breakthrough curves were collected for three unsaturated flow rates with silica microspheres and one unsaturated flow rate with ferrihydrite colloids. A moisture characteristic curve, relating tensiometer measurements of matric potential to moisture content, was developed for the fiberglass wick. Results indicate that retention of the silica and the ferrihydrite on the wick occurred; that is, the wicks did not facilitate quantitative sampling of the colloids. For silica microspheres, 90% of the colloids were transmitted through the wicks. For ferrihydrite, 80 to 90% of the colloids were transmitted. The mechanisms responsible for the retention of the colloids on the fiberglass wicks appeared to be physicochemical attachment and not thin-film, triple-phase entrapment, or mechanical straining. Visualization of pathways by iron staining indicates that flow is preferential at the center of twisted bundles of filaments. Although axial preferential flow in PCAPS may enhance their hydraulic suitability for sampling mobile colloids, we conclude that without specific preparation to reduce attachment or retention, fiberglass wicks should only be used for qualitative sampling of pore water colloids.

  20. Development of novel biocompatible hybrid nanocomposites based on polyurethane-silica prepared by sol gel process

    Energy Technology Data Exchange (ETDEWEB)

    Rashti, Ali [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Yahyaei, Hossein [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Firoozi, Saman [Department of Tissue Engineering & Regenerative Medicine, Faculty of Advanced Technologies in Medicine, Iran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Ramezani, Sara [Department of Neuroscience, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Rahiminejad, Ali [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Karimi, Roya [Department of Tissue Engineering and Applied Cell Science, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Farzaneh, Khadijeh [Tehran Heart Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Mohseni, Mohsen [Department of Polymer Engineering and Color Technology, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Ghanbari, Hossein, E-mail: hghanbari@tums.ac.ir [Department of Medical Nanotechnology, School of Advanced Technologies in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Tehran Heart Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Medical Biomaterials Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

    2016-12-01

    Due to high biocompatibility, polyurethane has found many applications, particularly in development of biomedical devices. A new nanocomposite based on thermoset polyurethane and silica nanoparticles was synthesized using sol-gel method. Sol-gel process was fulfilled in two acidic and basic conditions by using tetraethylorthosilicate (TEOS) and trimethoxyisocyanatesilane as precursors. The hybrid films characterized for mechanical and surface properties using tensile strength, contact angle, ATR-FTIR and scanning electron microscopy. Biocompatibility and cytotoxicity of the hybrids were assessed using standard MTT, LDH and TUNEL assays. The results revealed that incorporation of silica nanoparticles was significantly improved tensile strength and mechanical properties of the hybrids. Based on the contact angle results, silica nanoparticles increased hydrophilicity of the hybrids. Biocompatibility by using human lung epithelial cell line (MRC-5) demonstrated that the hybrids were significantly less cytotoxic compared to pristine polymer as tested by MTT and LDH assays. TUNEL assay revealed no signs of apoptosis in all tested samples. The results of this study demonstrated that incorporation of silica nanoparticles into polyurethane lead to the enhancement of biocompatibility, indicating that these hybrids could potentially be used in biomedical field in particular as a new coating for medical implants. - Highlights: • Nanocomposites based on polyurethane and nanosilica prepared by sol-gel method fabricated • Addition of inorganic phase improved mechanical properties. • Nanosilica prepared by sol-gel method increased hydrophilicity. • By adding nanosilica to polyurethane biocompatibility increased significantly.

  1. Silica ecosystem for synergistic biotransformation

    Science.gov (United States)

    Mutlu, Baris R.; Sakkos, Jonathan K.; Yeom, Sujin; Wackett, Lawrence P.; Aksan, Alptekin

    2016-06-01

    Synergistical bacterial species can perform more varied and complex transformations of chemical substances than either species alone, but this is rarely used commercially because of technical difficulties in maintaining mixed cultures. Typical problems with mixed cultures on scale are unrestrained growth of one bacterium, which leads to suboptimal population ratios, and lack of control over bacterial spatial distribution, which leads to inefficient substrate transport. To address these issues, we designed and produced a synthetic ecosystem by co-encapsulation in a silica gel matrix, which enabled precise control of the microbial populations and their microenvironment. As a case study, two greatly different microorganisms: Pseudomonas sp. NCIB 9816 and Synechococcus elongatus PCC 7942 were encapsulated. NCIB 9816 can aerobically biotransform over 100 aromatic hydrocarbons, a feat useful for synthesis of higher value commodity chemicals or environmental remediation. In our system, NCIB 9816 was used for biotransformation of naphthalene (a model substrate) into CO2 and the cyanobacterium PCC 7942 was used to provide the necessary oxygen for the biotransformation reactions via photosynthesis. A mathematical model was constructed to determine the critical cell density parameter to maximize oxygen production, and was then used to maximize the biotransformation rate of the system.

  2. Plasma-deposited hybrid silica membranes with a controlled retention of organic bridges

    Energy Technology Data Exchange (ETDEWEB)

    Ngamou, P.H.T.; Creatore, M. [Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Overbeek, J.P.; Kreiter, R.; Van Veen, H.M.; Vente, J.F. [ECN, Energy research Centre of the Netherlands, Petten (Netherlands); Wienk, I.M.; Cuperus, P.F. [SolSep BV, Apeldoorn (Netherlands)

    2013-03-05

    Hybrid organically bridged silica membranes are suitable for energy-efficient molecular separations under harsh industrial conditions. Such membranes can be useful in organic solvent nanofiltration if they can be deposited on flexible, porous and large area supports. Here, we report the proof of concept for applying an expanding thermal plasma to the synthesis of perm-selective hybrid silica films from an organically bridged monomer, 1,2-bis(triethoxysilyl)ethane. This membrane is the first in its class to be produced by plasma enhanced chemical vapor deposition. By tuning the plasma and process parameters, the organic bridging groups could be retained in the separating layer. This way, a defect free film could be made with pervaporation performances of an n-butanol-water mixture comparable with those of conventional ceramic supported membranes made by sol-gel technology (i.e. a water flux of [similar]1.8 kg m'-{sup 2} h{sup -1}, a water concentration in the permeate higher than 98% and a separation factor of >1100). The obtained results show the suitability of expanding thermal plasma as a technology for the deposition of hybrid silica membranes for molecular separations.

  3. Multilayered gold/silica nanoparticulate bilayer devices using layer-by-layer self organisation for flexible bending and pressure sensing applications

    Energy Technology Data Exchange (ETDEWEB)

    Shah Alam, Md. [Department of Electrical and Electronic Engineering, Rajshahi University of Engineering and Technology, Rajshahi 6204 (Bangladesh); Center of Excellence in Nanotechnology, Asian Institute of Technology, 12120 Pathumthani (Thailand); Mohammed, Waleed S., E-mail: waleed.m@bu.ac.th [Center of Research in Optoelectronics, Communication and Control System (BU-CROCCS), School of Engineering, Bangkok University, Pathumthani 12120 (Thailand); Dutta, Joydeep, E-mail: dutta@squ.edu.om [Center of Excellence in Nanotechnology, Asian Institute of Technology, 12120 Pathumthani (Thailand); Chair in Nanotechnology, Water Research Center, Sultan Qaboos University, P.O. Box 33, Al Khoud 123 (Oman)

    2014-02-17

    A pressure and bending sensor was fabricated using multilayer thin films fabricated on a flexible substrate based on layer-by-layer self-organization of 18 nm gold nanoparticles separated by a dielectric layer of 30 nm silica nanoparticles. 50, 75, and 100 gold-silica bi-layered films were deposited and the device characteristics were studied. A threshold voltage was required for electron conduction which increases from 2.4 V for 50 bi-layers to 3.3 V for 100 bi-layers. Upon bending of the device up to about 52°, the threshold voltage and slope of the I-V curves change linearly. Electrical characterization of the multilayer films was carried out under ambient conditions with different pressures and bending angles in the direct current mode. This study demonstrates that the developed multilayer thin films can be used as pressure as well as bending sensing applications.

  4. Some Durability Characteristics of Micro Silica and Nano Silica Contained Concrete

    Directory of Open Access Journals (Sweden)

    Mohammed Salah Nasr

    2016-12-01

    Full Text Available This paper aims to investigate the influence of replacement of cement with nano and micro silica admixtures on some durability properties of concrete such as water absorption, chloride content and pH tests. Three replacement ratios (5%,10%,15% of micro silica and four replacement proportions (0.5%,1.5%,3%,5% for nano silica were used in this study. Two exposure conditions were considered for chloride content test: wetting-drying and full immersing exposure in 6% of chloride ions solution, NaCl type. Results showed that mixes of %5 micro silica and 5% nano silica had lower content of chloride (about 0.19% and 0.18% for wetting-drying and full immersing exposure respectively. For water absorption test, all mixes incorporated micro and nano silica, except for %5 micro silica mix, showed lower absorption than control mixes. For pH test, results indicated that the adding of nano and micro silica didn’t affect adversely the alkalinity of concrete.

  5. Preparation of resveratrol-loaded nanoporous silica materials with different structures

    Science.gov (United States)

    Popova, Margarita; Szegedi, Agnes; Mavrodinova, Vesselina; Novak Tušar, Natasa; Mihály, Judith; Klébert, Szilvia; Benbassat, Niko; Yoncheva, Krassimira

    2014-11-01

    Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated. Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound.

  6. Growth and applicability of radiation-responsive silica nanowires

    Science.gov (United States)

    Bettge, Martin

    Surface energetics play an important role in processes on the nanoscale. Nanowire growth via vapor-liquid-solid (VLS) mechanism is no exception in this regard. Interfacial and line energies are found to impose some fundamental limits during three-phase nanowire growth and lead to formation of stranded nanowires with fascinating characteristics such as high responsiveness towards ion irradiation. By using two materials with a relatively low surface energy (indium and silicon oxide) this is experimentally and theoretically demonstrated in this doctoral thesis. The augmentation of VLS nanowire growth with ion bombardment enables fabrication of vertically aligned silica nanowires over large areas. Synthesis of their arrays begins with a thin indium film deposited on a Si or SiO 2 surface. At temperatures below 200ºC, the indium film becomes a self-organized seed layer of molten droplets, receiving a flux of atomic silicon by DC magnetron sputtering. Simultaneous vigorous ion bombardment through substrate biasing aligns the growing nanowires vertically and expedites mixing of oxygen and silicon into the indium. The vertical growth rate can reach up to 1000 nm-min-1 in an environment containing only argon and traces of water vapor. Silicon oxide precipitates from each indium seed in the form of multiple thin strands having diameters less than 9 nm and practically independent of droplet size. The strands form a single loose bundle, eventually consolidating to form one vertically aligned nanowire. These observations are in stark contrast to conventional VLS growth in which one liquid droplet precipitates a single solid nanowire and in which the precipitated wire diameter is directly proportional to the droplet diameter. The origin of these differences is revealed through a detailed force balance analysis, analogous to Young's relation, at the three-phase line. The liquid-solid interfacial energy of indium/silica is found to be the largest energy contribution at the three

  7. Thermal processing of EVA encapsulants and effects of formulation additives

    Energy Technology Data Exchange (ETDEWEB)

    Pern, F.J.; Glick, S.H. [National Renewable Energy Lab., Golden, CO (United States)

    1996-05-01

    The authors investigated the in-situ processing temperatures and effects of various formulation additives on the formation of ultraviolet (UV) excitable chromophores, in the thermal lamination and curing of ethylene-vinyl acetate (EVA) encapsulants. A programmable, microprocessor-controlled, double-bag vacuum laminator was used to study two commercial as formulated EVA films, A9918P and 15295P, and solution-cast films of Elvaxrm (EVX) impregnated with various curing agents and antioxidants. The results show that the actual measured temperatures of EVA lagged significantly behind the programmed profiles for the heating elements and were affected by the total thermal mass loaded inside the laminator chamber. The antioxidant Naugard P{trademark}, used in the two commercial EVA formulations, greatly enhances the formation of UV-excitable, short chromophores upon curing, whereas other tested antioxidants show little effect. A new curing agent chosen specifically for the EVA formulation modification produces little or no effect on chromophore formation, no bubbling problems in the glass/EVX/glass laminates, and a gel content of {approximately}80% when cured at programmed 155{degrees}C for 4 min. Also demonstrated is the greater discoloring effect with higher concentrations of curing-generated chromophores.

  8. Novel Formulations for Antimicrobial Peptides

    Directory of Open Access Journals (Sweden)

    Ana Maria Carmona-Ribeiro

    2014-10-01

    Full Text Available Peptides in general hold much promise as a major ingredient in novel supramolecular assemblies. They may become essential in vaccine design, antimicrobial chemotherapy, cancer immunotherapy, food preservation, organs transplants, design of novel materials for dentistry, formulations against diabetes and other important strategical applications. This review discusses how novel formulations may improve the therapeutic index of antimicrobial peptides by protecting their activity and improving their bioavailability. The diversity of novel formulations using lipids, liposomes, nanoparticles, polymers, micelles, etc., within the limits of nanotechnology may also provide novel applications going beyond antimicrobial chemotherapy.

  9. Novel Formulations for Antimicrobial Peptides

    Science.gov (United States)

    Carmona-Ribeiro, Ana Maria; Carrasco, Letícia Dias de Melo

    2014-01-01

    Peptides in general hold much promise as a major ingredient in novel supramolecular assemblies. They may become essential in vaccine design, antimicrobial chemotherapy, cancer immunotherapy, food preservation, organs transplants, design of novel materials for dentistry, formulations against diabetes and other important strategical applications. This review discusses how novel formulations may improve the therapeutic index of antimicrobial peptides by protecting their activity and improving their bioavailability. The diversity of novel formulations using lipids, liposomes, nanoparticles, polymers, micelles, etc., within the limits of nanotechnology may also provide novel applications going beyond antimicrobial chemotherapy. PMID:25302615

  10. In vitro⿿in vivo performance of bare and drug loaded silica gel synthesized via optimized process parameters

    Science.gov (United States)

    Chakraborty, Suparna; Biswas, Supratim

    2016-01-01

    Silica xerogel as a potential drug carrier system for the in vivo as well as in vitro delivery of andrographolide was tested. The present study aims to optimize the effective experimental parameters; volume of ethanol, volume of water and drying temperature by applying response surface methodology coupled with Box⿿Behnken experimental design. The in vitro drug release in simulated body fluid at 37 οC from the selected formulation was significantly highest (44.83 ± 0.9%) among rest of the formulations. Results indicate that sol⿿gel method is useful for entrapping andrographolide in the silica gel and for releasing the same via diffusion through the porous matrix under the in vitro/in vivo conditions. Silica gel exhibited slow matrix degradation as well as sustained release of andrographolide within the experimental time frame of 168 h. In vivo study was performed with three increasing doses [2 mg (S1), 8 mg (S2), and 16 mg (S3)] of silica. Histological fates of different organs were executed with those doses.

  11. Processing, adhesion and electrical properties of silicon steel having non-oriented grains coated with silica and alumina sol-gel

    International Nuclear Information System (INIS)

    Vasconcelos, D.C.L.; Orefice, R.L.; Vasconcelos, W.L.

    2007-01-01

    Silicon steels having non-oriented grains are usually coated with a series of inorganic or organic films to be used in electrical applications. However, the commercially available coatings have several disadvantages that include poor adhesion to the substrates, low values of electrical resistance and degradation at higher temperatures. In this work, silica and alumina sol-gel films were deposited onto silicon steel in order to evaluate the possibility of replacing the commercially available coatings by these sol-gel derived materials. Silica and alumina sol-gel coatings were prepared by dipping silicon steel samples into hydrolyzed silicon or aluminum alkoxides. Samples coated with sol-gel films were studied by scanning electron microscopy, energy dispersive spectroscopy and infrared spectroscopy. Adhesion between silicon steel and sol-gel films was measured by using several standard adhesion tests. Electrical properties were evaluated by the Franklin method. Results showed that homogeneous sol-gel films can be deposited onto silicon steel. Thicknesses of the films could be easily managed by altering the speed of deposition. The structure of the films could also be tailored by introducing additives, such as nitric acid and N,N-dimethyl formamide. Adhesion tests revealed a high level of adhesion between coatings and metal. The Franklin test showed that sol-gel films can produce coated samples with electrical resistances suitable for electrical applications. Electrical properties of the coated samples could also be manipulated by altering the structure of the sol-gel films or by changing the thickness of them

  12. Surfactant adsorption and aggregate structure of silica nanoparticles: a versatile stratagem for the regulation of particle size and surface modification

    International Nuclear Information System (INIS)

    Chaudhary, Savita; Rohilla, Deepak; Mehta, S K

    2014-01-01

    The area of silica nanoparticles is incredibly polygonal. Silica particles have aroused exceptional deliberation in bio-analysis due to great progress in particular arenas, for instance, biocompatibility, unique properties of modifiable pore size and organization, huge facade areas and pore volumes, manageable morphology and amendable surfaces, elevated chemical and thermal stability. Currently, silica nanoparticles participate in crucial utilities in daily trade rationales such as power storage, chemical and genetic sensors, groceries dispensation and catalysis. Herein, the size-dependent interfacial relation of anionic silica nanoparticles with twelve altered categories of cationic surfactants has been carried out in terms of the physical chemical facets of colloid and interface science. The current analysis endeavours to investigate the virtual consequences of different surfactants through the development of the objective composite materials. The nanoparticle size controls, the surface-to-volume ratio and surface bend relating to its interaction with surfactant will also be addressed in this work. More importantly, the simulated stratagem developed in this work can be lengthened to formulate core–shell nanostructures with functional nanoparticles encapsulated in silica particles, making this approach valuable and extensively pertinent for employing sophisticated materials for catalysis and drug delivery. (papers)

  13. Lyophilized silica lipid hybrid (SLH) carriers for poorly water-soluble drugs: physicochemical and in vitro pharmaceutical investigations.

    Science.gov (United States)

    Yasmin, Rokhsana; Tan, Angel; Bremmell, Kristen E; Prestidge, Clive A

    2014-09-01

    Lyophilization was investigated to produce a powdery silica-lipid hybrid (SLH) carrier for oral delivery of poorly water-soluble drugs. The silica to lipid ratio, incorporation of cryoprotectant, and lipid loading level were investigated as performance indicators for lyophilized SLH carriers. Celecoxib, a nonsteroidal anti-inflammatory drug, was used as the model poorly soluble moiety to attain desirable physicochemical and in vitro drug solubilization properties. Scanning electron microscopy and confocal fluorescence imaging verified a nanoporous, homogenous internal matrix structures of the lyophilized SLH particles, prepared from submicron triglyceride emulsions and stabilized by porous silica nanoparticles (Aerosil 380), similar to spray-dried SLH. 20-50 wt % of silica in the formulation have shown to produce nonoily SLH agglomerates with complete lipid encapsulation. The incorporation of a cryoprotectant prevented irreversible aggregation of the silica-stabilized droplets during lyophilization, thereby readily redispersing in water to form micrometre-sized particles (water-soluble therapeutics is confirmed. © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

  14. Characteristics of supported nano-TiO{sub 2}/ZSM-5/silica gel (SNTZS): Photocatalytic degradation of phenol

    Energy Technology Data Exchange (ETDEWEB)

    Zainudin, Nor Fauziah; Abdullah, Ahmad Zuhairi [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Penang (Malaysia); Mohamed, Abdul Rahman, E-mail: chrahman@eng.usm.my [School of Chemical Engineering, Engineering Campus, Universiti Sains Malaysia, Seri Ampangan, 14300 Nibong Tebal, Penang (Malaysia)

    2010-02-15

    Photocatalytic degradation of phenol was investigated using the supported nano-TiO{sub 2}/ZSM-5/silica gel (SNTZS) as a photocatalyst in a batch reactor. The prepared photocatalyst was characterized using XRD, TEM, FT-IR and BET surface area analysis. The synthesized photocatalyst composition was developed using nano-TiO{sub 2} as the photoactive component and zeolite (ZSM-5) as the adsorbents, all supported on silica gel using colloidal silica gel binder. The optimum formulation of SNTZS catalyst was observed to be (nano-TiO{sub 2}:ZSM-5:silica gel:colloidal silica gel = 1:0.6:0.6:1) which giving about 90% degradation of 50 mg/L phenol solution in 180 min. The SNTZS exhibited higher photocatalytic activity than that of the commercial Degussa P25 which only gave 67% degradation. Its high photocatalytic activity was due to its large specific surface area (275.7 m{sup 2}/g), small particle size (8.1 nm), high crystalline quality of the synthesized catalyst and low electron-hole pairs recombination rate as ZSM-5 adsorbent was used. The SNTZS photocatalyst synthesized in this study also has been proven to have an excellent adhesion and reusability.

  15. Characteristics of supported nano-TiO2/ZSM-5/silica gel (SNTZS): Photocatalytic degradation of phenol

    International Nuclear Information System (INIS)

    Zainudin, Nor Fauziah; Abdullah, Ahmad Zuhairi; Mohamed, Abdul Rahman

    2010-01-01

    Photocatalytic degradation of phenol was investigated using the supported nano-TiO 2 /ZSM-5/silica gel (SNTZS) as a photocatalyst in a batch reactor. The prepared photocatalyst was characterized using XRD, TEM, FT-IR and BET surface area analysis. The synthesized photocatalyst composition was developed using nano-TiO 2 as the photoactive component and zeolite (ZSM-5) as the adsorbents, all supported on silica gel using colloidal silica gel binder. The optimum formulation of SNTZS catalyst was observed to be (nano-TiO 2 :ZSM-5:silica gel:colloidal silica gel = 1:0.6:0.6:1) which giving about 90% degradation of 50 mg/L phenol solution in 180 min. The SNTZS exhibited higher photocatalytic activity than that of the commercial Degussa P25 which only gave 67% degradation. Its high photocatalytic activity was due to its large specific surface area (275.7 m 2 /g), small particle size (8.1 nm), high crystalline quality of the synthesized catalyst and low electron-hole pairs recombination rate as ZSM-5 adsorbent was used. The SNTZS photocatalyst synthesized in this study also has been proven to have an excellent adhesion and reusability.

  16. Synthesis of Macroporous Silica Particles by Continuous Generation of Droplets for Insulating Materials.

    Science.gov (United States)

    Cho, Young-Sang; Lee, Dokyoung

    2018-09-01

    We report on the synthesis of porous silica particles by self-assembly routes in a continuous manner for application to thermal insulators. A continuous process was employed to produce tiny droplets containing precursor materials such as silica and organic templates for self-organization to fabricate particles with well defined pores. A rotating cylinder system or a spray drying process was adopted to form emulsions or aerosol droplets as micro-reactors for self-assembly, and the physical properties including the thermal conductivity of the resulting porous particles were compared between the two methods. The porous particles could be coated as a thick film by solution dripping, and the fluorination treatment using a silane coupling agent was performed to produce superhydrophobic surfaces of insulating layers by a lotus effect.

  17. Structure and Properties of LENRA/ Silica Composite

    International Nuclear Information System (INIS)

    Mahathir Mohamed; Dahlan Mohd

    2010-01-01

    The sol-gel reaction using tetra ethoxysilane (TEOS) was conducted for modified natural rubber (NR) matrix to obtain in situ generated NR/ silica composite. The present of acrylate group in the modified NR chain turns the composite into radiation-curable. The maximum amount of silica generated in the matrix was 50 p hr by weight. During the sol-gel process the inorganic mineral was deposited in the rubber matrix forming hydrogen bonding between organic and inorganic phases. The composites obtained were characterized by various techniques including thermogravimetric analysis and infrared spectrometry to study their molecular structure. The increase in mechanical properties was observed for low silica contents ( 30 p hr) where more silica were generated, agglomerations were observed at the expense of the mechanical properties. From the DMTA data, it shows an increase of the interaction between the rubber and silica phases up to 30 p hr TEOS. Structure and morphology of the heterogeneous system were analyzed by transmission electron microscopy. The average particle sizes of between 150 nm to 300 nm were achieved for the composites that contain less than 20 p hr of TEOS. (author)

  18. Two-Stage Crystallizer Design for High Loading of Poorly Water-Soluble Pharmaceuticals in Porous Silica Matrices

    OpenAIRE

    Leia Dwyer; Samir Kulkarni; Luzdary Ruelas; Allan Myerson

    2017-01-01

    While porous silica supports have been previously studied as carriers for nanocrystalline forms of poorly water-soluble active pharmaceutical ingredients (APIs), increasing the loading of API in these matrices is of great importance if these carriers are to be used in drug formulations. A dual-stage mixed-suspension, mixed-product removal (MSMPR) crystallizer was designed in which the poorly soluble API fenofibrate was loaded into the porous matrices of pore sizes 35 nm-300 nm in the first st...

  19. Neonates need tailored drug formulations.

    Science.gov (United States)

    Allegaert, Karel

    2013-02-08

    Drugs are very strong tools used to improve outcome in neonates. Despite this fact and in contrast to tailored perfusion equipment, incubators or ventilators for neonates, we still commonly use drug formulations initially developed for adults. We would like to make the point that drug formulations given to neonates need to be tailored for this age group. Besides the obvious need to search for active compounds that take the pathophysiology of the newborn into account, this includes the dosage and formulation. The dosage or concentration should facilitate the administration of low amounts and be flexible since clearance is lower in neonates with additional extensive between-individual variability. Formulations need to be tailored for dosage variability in the low ranges and also to the clinical characteristics of neonates. A specific focus of interest during neonatal drug development therefore is a need to quantify and limit excipient exposure based on the available knowledge of their safety or toxicity. Until such tailored vials and formulations become available, compounding practices for drug formulations in neonates should be evaluated to guarantee the correct dosing, product stability and safety.

  20. Silica nanoparticles as the adjuvant for the immunisation of mice using hepatitis B core virus-like particles.

    Directory of Open Access Journals (Sweden)

    Dace Skrastina

    Full Text Available Advances in nanotechnology and nanomaterials have facilitated the development of silicon dioxide, or Silica, particles as a promising immunological adjuvant for the generation of novel prophylactic and therapeutic vaccines. In the present study, we have compared the adjuvanting potential of commercially available Silica nanoparticles (initial particles size of 10-20 nm with that of aluminium hydroxide, or Alum, as well as that of complete and incomplete Freund's adjuvants for the immunisation of BALB/c mice with virus-like particles (VLPs formed by recombinant full-length Hepatitis B virus core (HBc protein. The induction of B-cell and T-cell responses was studied after immunisation. Silica nanoparticles were able to adsorb maximally 40% of the added HBc, whereas the adsorption capacity of Alum exceeded 90% at the same VLPs/adjuvant ratio. Both Silica and Alum formed large complexes with HBc VLPs that sedimented rapidly after formulation, as detected by dynamic light scattering, spectrophotometry, and electron microscopy. Both Silica and Alum augmented the humoral response against HBc VLPs to the high anti-HBc level in the case of intraperitoneal immunisation, whereas in subcutaneous immunisation, the Silica-adjuvanted anti-HBc level even exceeded the level adjuvanted by Alum. The adjuvanting of HBc VLPs by Silica resulted in the same typical IgG2a/IgG1 ratios as in the case of the adjuvanting by Alum. The combination of Silica with monophosphoryl lipid A (MPL led to the same enhancement of the HBc-specific T-cell induction as in the case of the Alum and MPL combination. These findings demonstrate that Silica is not a weaker putative adjuvant than Alum for induction of B-cell and T-cell responses against recombinant HBc VLPs. This finding may have an essential impact on the development of the set of Silica-adjuvanted vaccines based on a long list of HBc-derived virus-like particles as the biological component.

  1. Microcanonical formulation of quantum field theories

    International Nuclear Information System (INIS)

    Iwazaki, A.

    1984-03-01

    A microcanonical formulation of Euclidean quantum field theories is presented. In the formulation, correlation functions are given by a microcanonical ensemble average of fields. Furthermore, the perturbative equivalence of the formulation and the standard functional formulation is proved and the equipartition low is derived in our formulation. (author)

  2. Thin films

    International Nuclear Information System (INIS)

    Strongin, M.; Miller, D.L.

    1976-01-01

    This article reviews the phenomena that occur in films from the point of view of a solid state physicist. Films form the basis for many established and developing technologies. Metal layers have always been important for optical coatings and as protective coatings. In the most sophisticated cases, films and their interaction on silicon surfaces form the basis of modern electronic technology. Films of silicon, GaAs and composites of these materials promise to lead to practical photovoltaic devices

  3. Nuclear films

    International Nuclear Information System (INIS)

    Malone, Peter.

    1985-01-01

    This booklet is a resource for the study of feature films that highlight the theme of nuclear war. It provides basic credits and brief indication of the theme, treatment, quality and particular notable aspects; and a series of questions raised by the film. Seventy feature films and thirty documentaries are examined

  4. CdS thin films prepared by continuous wave Nd:YAG laser

    Science.gov (United States)

    Wang, H.; Tenpas, Eric W.; Vuong, Khanh D.; Williams, James A.; Schuesselbauer, E.; Bernstein, R.; Fagan, J. G.; Wang, Xing W.

    1995-08-01

    We report new results on continuous wave Nd:YAG laser deposition of cadmium sulfide thin films. Substrates were soda-lime silicate glass, silica glass, silicon, and copper coated formvar sheets. As deposited films were mixtures of cubic and hexagonal phases, with two different grain sizes. As revealed by SEM micrographs, films had smooth surface morphology. As revealed by TEM analysis, grain sizes were extremely small.

  5. In vitro testing of thiolated poly(aspartic acid) from ophthalmic formulation aspects.

    Science.gov (United States)

    Budai-Szű Cs, Mária; Horvát, Gabriella; Gyarmati, Benjámin; Szilágyi, Barnabás Áron; Szilágyi, András; Csihi, Tímea; Berkó, Szilvia; Szabó-Révész, Piroska; Mori, Michela; Sandri, Giuseppina; Bonferoni, Maria Cristina; Caramella, Carla; Csányi, Erzsébet

    2016-08-01

    Ocular drug delivery formulations must meet anatomical, biopharmaceutical, patient-driven and regulatory requirements. Mucoadhesive polymers can serve as a better alternative to currently available ophthalmic formulations by providing improved bioavailability. If all requirements are addressed, a polymeric formulation resembling the tear film of the eye might be the best solution. The optimum formulation must not have high osmotic activity, should provide appropriate surface tension, pH and refractive index, must be non-toxic and should be transparent and mucoadhesive. We would like to highlight the importance of in vitro polymer testing from a pharmaceutical aspect. We, therefore, carried out physical-chemical investigations to verify the suitability of certain systems for ophthalmic formulations. In this work, in situ gelling, mucoadhesive thiolated poly(aspartic acid)s were tested from ophthalmic formulation aspects. The results of preformulation measurements indicate that these polymers can be used as potential carriers in ophthalmic drug delivery.

  6. Multifunctional nanomedicine with silica: Role of silica in nanoparticles for theranostic, imaging, and drug monitoring.

    Science.gov (United States)

    Chen, Fang; Hableel, Ghanim; Zhao, Eric Ruike; Jokerst, Jesse V

    2018-07-01

    The idea of multifunctional nanomedicine that enters the human body to diagnose and treat disease without major surgery is a long-standing dream of nanomaterials scientists. Nanomaterials show incredible properties that are not found in bulk materials, but achieving multi-functionality on a single material remains challenging. Integrating several types of materials at the nano-scale is critical to the success of multifunctional nanomedicine device. Here, we describe the advantages of silica nanoparticles as a tool for multifunctional nano-devices. Silica nanoparticles have been intensively studied in drug delivery due to their biocompatibility, degradability, tunable morphology, and ease of modification. Moreover, silica nanoparticles can be integrated with other materials to obtain more features and achieve theranostic capabilities and multimodality for imaging applications. In this review, we will first compare the properties of silica nanoparticles with other well-known nanomaterials for bio-applications and describe typical routes to synthesize and integrate silica nanoparticles. We will then highlight theranostic and multimodal imaging application that use silica-based nanoparticles with a particular interest in real-time monitoring of therapeutic molecules. Finally, we will present the challenges and perspective on future work with silica-based nanoparticles in medicine. Copyright © 2018 Elsevier Inc. All rights reserved.

  7. Interfacial interaction between the epoxidized natural rubber and silica in natural rubber/silica composites

    Science.gov (United States)

    Xu, Tiwen; Jia, Zhixin; Luo, Yuanfang; Jia, Demin; Peng, Zheng

    2015-02-01

    The epoxidized natural rubber (ENR) as an interfacial modifier was used to improve the mechanical and dynamical mechanical properties of NR/silica composites. In order to reveal the interaction mechanism between ENR and silica, the ENR/Silica model compound was prepared by using an open mill and the interfacial interaction of ENR with silica was investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD) and stress-strain testing. The results indicated that the ring-opening reaction occurs between the epoxy groups of ENR chains and Si-OH groups on the silica surfaces and the covalent bonds are formed between two phases, which can improve the dispersion of silica in the rubber matrix and enhance the interfacial combination between rubber and silica. The ring-opening reaction occurs not only in vulcanization process but also in mixing process, meanwhile, the latter seems to be more important due to the simultaneous effects of mechanical force and temperature.

  8. Nanopatterning Gold by Templated Solid State Dewetting on the Silica Warp and Weft of Diatoms

    Directory of Open Access Journals (Sweden)

    Jon Hiltz

    2016-01-01

    Full Text Available The diatom, Nitzschia palea, exhibits complex silica shell (frustule topography that resembles the warp and weft pattern of woven glass. The surface is perforated with a rhombic lattice of roughly oblong pores between periodically undulating transverse weft costae. Exfoliated frustules can be used to template gold nanoparticles by thermally induced dewetting of thin gold films. Acting as templates for the process, the frustules give rise to two coexisting hierarchies of particle sizes and patterned distributions of nanoparticles. By examining temperature dependent dewetting of 5, 10, and 15 nm Au films for various annealing times, we establish conditions for particle formation and patterning. The 5 nm film gives distributions of small particles randomly distributed over the surface and multiple particles at the rhombic lattice points in the pores. Thicker films yield larger faceted particles on the surface and particles that exhibit shapes that are roughly conformal with the shape of the pore container. The pores and costae are sources of curvature instabilities in the film that lead to mass transport of gold and selective accumulation in the weft valleys and pores. We suggest that, with respect to dewetting, the frustule comprises 2-dimensional sublattices of trapping sites. The pattern of dewetting is radically altered by interposing a self-assembled molecular adhesive of mercaptopropyltrimethoxysilane between the Au film overlayer and the frustule. By adjusting the interfacial energy in this manner, a fractal-like overlay of Au islands coexists with a periodic distribution of nanoparticles in the pores.

  9. Study of the pluronic-silica interaction in synthesis of mesoporous silica under mild acidic conditions.

    Science.gov (United States)

    Sundblom, Andreas; Palmqvist, Anders E C; Holmberg, Krister

    2010-02-02

    The interaction between silica and poly(ethylene oxide) (PEO) in water may appear trivial and it is generally stated that hydrogen bonding is responsible for the attraction. However, a literature search shows that there is not a consensus with respect to the mechanism behind the attractive interaction. Several papers claim that only hydrogen bonding is not sufficient to explain the binding. The silica-PEO interaction is interesting from an academic perspective and it is also exploited in the preparation of mesoporous silica, a material of considerable current interest. This study concerns the very early stage of synthesis of mesoporous silica under mild acidic conditions, pH 2-5, and the aim is to shed light on the interaction between silica and the PEO-containing structure directing agent. The synthesis comprises two steps. An organic silica source, tetraethylorthosilicate (TEOS), is first hydrolyzed and Pluronic P123, a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymer, is subsequently added at different time periods following the hydrolysis of TEOS. It is shown that the interaction between the silica and the Pluronic is dependent both on the temperature and on the time between onset of TEOS hydrolysis and addition of the copolymer. The results show that the interaction is mainly driven by entropy. The effect of the synthesis temperature and of the time between hydrolysis and addition of the copolymer on the final material is also studied. The material with the highest degree of mesoorder was obtained when the reaction was performed at 20 degrees C and the copolymer was added 40 h after the start of TEOS hydrolysis. It is claimed that the reason for the good ordering of the silica is that whereas particle formation under these conditions is fast, the rate of silica condensation is relatively low.

  10. Molecular Dynamics Simulations of Water Droplets On Hydrophilic Silica Surfaces

    DEFF Research Database (Denmark)

    Zambrano, Harvey A; Walther, Jens Honore; Jaffe, Richard L.

    2009-01-01

    and DNA microarrays technologies.Although extensive experimental, theoretical and computational work has been devoted to study the nature of the interaction between silica and water, at the molecular level a complete understanding of silica-water systems has not been reached. Contact angle computations...... dynamics (MD) simulations of a hydrophilic air-water-silica system using the MD package FASTTUBE. We employ quantum chemistry calculation to obtain air-silica interaction parameters for the simulations. Our simulations are based in the following force fields: i) The silica-silica interaction is based...... of water droplets on silica surfaces offers a useful fundamental and quantitative measurement in order to study chemical and physical properties of water-silica systems. For hydrophobic systems the static and dynamic properties of the fluid-solid interface are influenced by the presence of air. Hence...

  11. Respiratory health effects of exposure to crystalline silica epidemiology.

    CSIR Research Space (South Africa)

    Hnzido, E

    1999-01-01

    Full Text Available The present report describes two additional studies of exposure-response relationship between respiratory disease and silica dust in gold mines. Section 3 describes a study of pulmonary tuberculosis in relation to silica dust, and section 4...

  12. Tactile friction of topical formulations.

    Science.gov (United States)

    Skedung, L; Buraczewska-Norin, I; Dawood, N; Rutland, M W; Ringstad, L

    2016-02-01

    The tactile perception is essential for all types of topical formulations (cosmetic, pharmaceutical, medical device) and the possibility to predict the sensorial response by using instrumental methods instead of sensory testing would save time and cost at an early stage product development. Here, we report on an instrumental evaluation method using tactile friction measurements to estimate perceptual attributes of topical formulations. Friction was measured between an index finger and an artificial skin substrate after application of formulations using a force sensor. Both model formulations of liquid crystalline phase structures with significantly different tactile properties, as well as commercial pharmaceutical moisturizing creams being more tactile-similar, were investigated. Friction coefficients were calculated as the ratio of the friction force to the applied load. The structures of the model formulations and phase transitions as a result of water evaporation were identified using optical microscopy. The friction device could distinguish friction coefficients between the phase structures, as well as the commercial creams after spreading and absorption into the substrate. In addition, phase transitions resulting in alterations in the feel of the formulations could be detected. A correlation was established between skin hydration and friction coefficient, where hydrated skin gave rise to higher friction. Also a link between skin smoothening and finger friction was established for the commercial moisturizing creams, although further investigations are needed to analyse this and correlations with other sensorial attributes in more detail. The present investigation shows that tactile friction measurements have potential as an alternative or complement in the evaluation of perception of topical formulations. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Thermodynamics of the silica-steam system

    Energy Technology Data Exchange (ETDEWEB)

    Krikorian, Oscar H [Lawrence Radiation Laboratory, University of California, Livermore, CA (United States)

    1970-05-01

    In most nuclear cratering and cavity formation applications, the working fluid in the expanding cavity consists primarily of vaporized silica and steam. The chemical reaction products of silica and steam under these conditions are not known, although it is known that silica is very volatile in the presence of high-pressure steam under certain geologic conditions and in steam turbines. A review is made of work on the silica-steam system in an attempt to determine the vapor species that exist, and to establish the associated thermo-dynamic data. The review indicates that at 600-900 deg K and 1-100 atm steam pressure, Si(OH){sub 4} is the most likely silicon-containing gaseous species. At 600-900 deg. K and 100-1000 atm steam, Si{sub 2}O(OH){sub 6} is believed to predominate, whereas at 1350 deg K and 2000-9000 atm, a mixture of Si(OH){sub 4} and Si{sub 2}O(OH){sub 6} is consistent with the observed volatilities. In work at 1760 deg. K in which silica was reacted either with steam at 0.5 and 1 atm, or with gaseous mixtures of H{sub 2}/H{sub 2}O and O{sub 2}/H{sub 2}O at 1 atm total pressure, only part of the volatility could be accounted for by Si(OH){sub 4}. Hydrogen was found to greatly enhance the volatility of silica, and oxygen to suppress it. The species most likely to explain this behavior is believed to be SiO(OH). A number of other species may also be significant under these conditions. Thermodynamic data have been estimated for all species considered. The Si-OH bond dissociation energy is found to be {approx}117 kcal/mole in both Si(OH){sub 4} and Si{sub 2}O(OH){sub 6}. (author)

  14. Micromagnetic study of single-domain FePt nanocrystals overcoated with silica

    International Nuclear Information System (INIS)

    Hyun, Changbae; Lee, Doh C; Korgel, Brian A; Lozanne, Alex de

    2007-01-01

    Chemically-synthesized FePt nanocrystals must be annealed at a high temperature (>550 deg. C) to induce the hard ferromagnetic L 1 0 phase. Unfortunately, the organic stabilizer covering these nanocrystals degrades at these temperatures and the nanocrystals sinter, resulting in the loss of control over nanocrystal size and separation in the film. We have developed a silica overcoating strategy to prevent nanocrystal sintering. In this study, 6 nm diameter FePt nanocrystals were coated with 17 nm thick shells of silica using an inverse micelle process. Magnetization measurements of the annealed FePt-SiO 2 nanocrystals indicate ferromagnetism with a high coercivity at room temperature. Magnetic force microscopy (MFM) results show that the film composed of nanocrystals behaves as a dipole after magnetization by an 8 T external field. The individual nanocrystals are modelled as single-domain particles with random crystallographic orientations. We propose that the interparticle magnetic dipole interaction is weaker than the magnetocrystalline energy in the remanent state, leading to an unusual material with no magnetic anisotropy and no domains. Films of these nanoparticles are promising candidates for magnetic media with a data storage density of ∼Tb/in 2

  15. Characterization, sensorial evaluation and moisturizing efficacy of nanolipidgel formulations.

    Science.gov (United States)

    Estanqueiro, M; Conceição, J; Amaral, M H; Sousa Lobo, J M

    2014-04-01

    Nanostructured lipid carriers (NLC) have been widely studied for cosmetic and dermatological applications due to their favourable properties that include the formation of an occlusive film on the skin surface that reduces the transepidermal water loss (TEWL) and increase in water content in the skin which improves the appearance on healthy human skin and reduces symptoms of some skin disorders like eczema. The main objective of this study was the development of semisolid formulations based NLC with argan oil or jojoba oil as liquid lipids, by addition of Carbopol®934 or Carbopol®980 as gelling agents, followed by comparison between instrumental analysis and sensorial evaluation and in vivo efficacy evaluation. Nanostructured lipid carriers dispersions were produced by the ultrasound technique, and to obtain a semisolid formulation, gelling agents were dispersed in the aqueous dispersion. Particle size, polydispersity index and zeta potential were determined. Instrumental characterization was performed by rheological and textural analysis; the sensorial evaluation was also performed. Finally, skin hydration and TEWL were studied by capacitance and evaporimetry evaluation, respectively. Particles showed a nanometric size in all the analysed formulations. All the gels present pseudoplastic behaviour. There is a correspondence between the properties firmness and adhesiveness as determined by textural analysis and the sensory evaluation. The formulations that showed a greater increase in skin hydration also presented appropriate technological and sensorial attributes for skin application. Nanolipidgel formulations with the addition of humectants are promising systems for cosmetic application with good sensory and instrumental attributes and moisturizing efficacy.

  16. Ordered mesoporous silica materials with complicated structures

    KAUST Repository

    Han, Yu

    2012-05-01

    Periodically ordered mesoporous silicas constitute one of the most important branches of porous materials that are extensively employed in various chemical engineering applications including adsorption, separation and catalysis. This short review gives an introduction to recently developed mesoporous silicas with emphasis on their complicated structures and synthesis mechanisms. In addition, two powerful techniques for solving complex mesoporous structures, electron crystallography and electron tomography, are compared to elucidate their respective strength and limitations. Some critical issues and challenges regarding the development of novel mesoporous structures as well as their applications are also discussed. © 2011 Elsevier Ltd.

  17. Silica-scaled chrysophytes of Lake Baikal

    Directory of Open Access Journals (Sweden)

    A. Yu. Bessudova

    2017-12-01

    Full Text Available The list of silica-scaled chrysophytes of Lake Baikal has been enlarged using electron microscopy. It has been supplemented with 12 species and 2 forms. Spiniferomonas takahashii has been observed for the first time in the water bodies of Russia. According to our data, the list of silica-scaled chrysophytes of Lake Baikal includes 25 species and intra-species taxa: Chrysosphaerella – 3, Paraphysomonas – 2, Clathromonas – 1, Spiniferomonas – 7, Mallomonas – 8 and Synura – 4. We have also analyzed their seasonal dynamics and observed algal species that are dominant in spring, summer and autumn.

  18. Formation of Uniform Hollow Silica microcapsules

    Science.gov (United States)

    Yan, Huan; Kim, Chanjoong

    2013-03-01

    Microcapsules are small containers with diameters in the range of 0.1 - 100 μm. Mesoporous microcapsules with hollow morphologies possess unique properties such as low-density and high encapsulation capacity, while allowing controlled release by permeating substances with a specific size and chemistry. Our process is a one-step fabrication of monodisperse hollow silica capsules with a hierarchical pore structure and high size uniformity using double emulsion templates obtained by the glass-capillary microfluidic technique to encapsulate various active ingredients. These hollow silica microcapsules can be used as biomedical applications such as drug delivery and controlled release.

  19. Measurement and modelization of silica opal optical properties

    OpenAIRE

    Avoine , Amaury; Ngoc Hong , Phan; Frederich , Hugo; Aregahegn , Kifle; Bénalloul , Paul; Coolen , Laurent; Schwob , Catherine; Thu Nga , Pham; Gallas , Bruno; Maître , Agnès

    2014-01-01

    International audience; We present the synthesis process and optical characterization of artificial silica opals. The specular reflection spectra are analyzed and compared to band structure calculations and finite difference time domain (FDTD) simulations. The silica optical index is a key parameter to correctly describe an opal and is usually not known and treated as a free parameter. Here we propose a method to infer the silica index, as well as the silica spheres diameter, from the reflect...

  20. Synthesis of Various Silica Nanoparticles for Foam Stability

    International Nuclear Information System (INIS)

    Yoon, Suk Bon; Yoon, Inho; Jung, Chonghun; Kim, Chorong; Choi, Wangkyu; Moon, Jeikwon

    2013-01-01

    The synthesis of the non-porous silica nanoparticles with uniform sizes has been reported through the Sto ber method, the synthesis of meso porous silica nanoparticles with a specific morphology such as core-shell, rod-like, and hexagonal shapes is not so common. As a synthetic strategy for controlling the particle size, shape, and porosity, the synthesis of core-shell silicas with meso porous shells formed on silica particle cores through the self-assembly of silica precursor and organic templates or spherical meso porous silicas using modified Sto ber method was also reported. Recently, in an effort to reduce the amount of radioactive waste and enhance the decontamination efficiency during the decontamination process of nuclear facilities contaminated with radionuclides, a few research for the preparation of the decontamination foam containing solid nanoparticles has been reported. In this work, the silica nanoparticles with various sizes, shapes, and structures were synthesized based on the previous literatures. The resulting silica nanoparticles were used to investigate the effect of the nanoparticles on the foam stability. In a study on the foam stability using various silica nanoparticles, the results showed that the foam volume and liquid volume in foam was enhanced when using a smaller size and lower density of the silica nanoparticles. Silica nanoparticles with various sizes, shapes, and structures such as a non-porous, meso porous core-shell, and meso porous silica were synthesized to investigate the effect of the foam stability. The sizes and structural properties of the silica nanoparticles were easily controlled by varying the amount of silica precursor, surfactant, and ammonia solution as a basic catalyst. The foam prepared using various silica nanoparticles showed that foam the volume and liquid volume in the foam were enhanced when using a smaller size and lower density of the silica nanoparticles

  1. Effects of annealing time on the structure, morphology, and stress of gold–chromium bilayer film

    International Nuclear Information System (INIS)

    Zhang Hong; Wang Hu; Huang Hao-Peng; Jin Yun-Xia; Kong Fang-Yu; Cui Yun

    2016-01-01

    In this work, a 200-nm-thick gold film with a 10-nm-thick chromium layer used as an adhesive layer is fabricated on fused silica by the electron beam evaporation method. The effects of annealing time at 300 °C on the structure, morphology and stress of the film are studied. We find that chromium could diffuse to the surface of the film by formatting a solid solution with gold during annealing. Meanwhile, chromium is oxidized on the surface and diffused downward along the grain grooves in the gold film. The various operant mechanisms that change the residual stresses of gold films for different annealing times are discussed. (paper)

  2. Decontamination formulation with sorbent additive

    Science.gov (United States)

    Tucker; Mark D. , Comstock; Robert H.

    2007-10-16

    A decontamination formulation and method of making that neutralizes the adverse health effects of both chemical and biological compounds, especially chemical warfare (CW) and biological warfare (BW) agents, and toxic industrial chemicals. The formulation provides solubilizing compounds that serve to effectively render the chemical and biological compounds, particularly CW and BW compounds, susceptible to attack, and at least one reactive compound that serves to attack (and detoxify or kill) the compound. The formulation includes at least one solubilizing agent, a reactive compound, a bleaching activator, a sorbent additive, and water. The highly adsorbent, water-soluble sorbent additive (e.g., sorbitol or mannitol) is used to "dry out" one or more liquid ingredients, such as the liquid bleaching activator (e.g., propylene glycol diacetate or glycerol diacetate) and convert the activator into a dry, free-flowing powder that has an extended shelf life, and is more convenient to handle and mix in the field.

  3. Formulation and Characterization of Potential Antifungal Oleogel with Essential Oil of Thyme

    Directory of Open Access Journals (Sweden)

    Giedre Kasparaviciene

    2018-01-01

    Full Text Available The aim of this research was to formulate oleogel with thyme essential oil with potential antimicrobial activity, design optimal formulation, and evaluate the influence of ingredients on texture parameters of preparation. Central composite design was applied to statistical optimization of colloidal silica and paraffin oil mixture for the modeling of oleogel delivery system. The influence of designed formulations on response variables (texture parameters, firmness, cohesiveness, consistency, and index of viscosity, was evaluated. Quality of essential oil of thyme was assessed by determinate concentration of thymol and carvacrol using gas chromatography with flame ionization detection (GC-FID. Microbiological tests have shown that oleogel with thyme essential oil affects Candida albicans microorganism when thyme essential oil’s concentration is 0,05% in oleogel mixture.

  4. A Variational approach to thin film hydrodynamics of binary mixtures

    KAUST Repository

    Xu, Xinpeng; Thiele, Uwe; Qian, Tiezheng

    2015-01-01

    In order to model the dynamics of thin films of mixtures, solutions, and suspensions, a thermodynamically consistent formulation is needed such that various coexisting dissipative processes with cross couplings can be correctly described

  5. New Silica Magnetite Sorbent: The Influence of Variations of Sodium Silicate Concentrations on Silica Magnetite Character

    Science.gov (United States)

    Azmiyawati, C.; Pratiwi, P. I.; Darmawan, A.

    2018-04-01

    The adsorption capacity of an adsorbent is determined by the adsorbent and the adsorbate properties. The character of the adsorbent will play a major role in its ability to adsorb the corresponding adsorbate. Therefore, in this study we looked at the effects of variations of sodium silicate concentrations on the resulting magnetite silica adsorbent properties. The application of silica coating on the magnetite was carried out through a sol-gel process with sodium silicate and HCl precursors. Based on the characterization data obtained, it was found that the silica coating on magnetite can increase the resistance to acid leaching, increase the particle size, but decrease the magnetic properties of the magnetite. Based on Gas Sorption Analyzer (GSA) and X-ray Difraction (XRD) data it can successively be determined that increase in concentration of sodium silicate will increase the surface area and amorphous structure of the Silica Magnetie.

  6. Surface engineering on mesoporous silica chips for enriching low molecular weight phosphorylated proteins

    Science.gov (United States)

    Hu, Ye; Peng, Yang; Lin, Kevin; Shen, Haifa; Brousseau, Louis C., III; Sakamoto, Jason; Sun, Tong; Ferrari, Mauro

    2011-02-01

    Phosphorylated peptides and proteins play an important role in normal cellular activities, e.g., gene expression, mitosis, differentiation, proliferation, and apoptosis, as well as tumor initiation, progression and metastasis. However, technical hurdles hinder the use of common fractionation methods to capture phosphopeptides from complex biological fluids such as human sera. Herein, we present the development of a dual strategy material that offers enhanced capture of low molecular weight phosphoproteins: mesoporous silica thin films with precisely engineered pore sizes that sterically select for molecular size combined with chemically selective surface modifications (i.e. Ga3+, Ti4+ and Zr4+) that target phosphoroproteins. These materials provide high reproducibility (CV = 18%) and increase the stability of the captured proteins by excluding degrading enzymes, such as trypsin. The chemical and physical properties of the composite mesoporous thin films were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy and ellipsometry. Using mass spectroscopy and biostatistics analysis, the enrichment efficiency of different metal ions immobilized on mesoporous silica chips was investigated. The novel technology reported provides a platform capable of efficiently profiling the serum proteome for biomarker discovery, forensic sampling, and routine diagnostic applications.Phosphorylated peptides and proteins play an important role in normal cellular activities, e.g., gene expression, mitosis, differentiation, proliferation, and apoptosis, as well as tumor initiation, progression and metastasis. However, technical hurdles hinder the use of common fractionation methods to capture phosphopeptides from complex biological fluids such as human sera. Herein, we present the development of a dual strategy material that offers enhanced capture of low molecular weight phosphoproteins: mesoporous

  7. Laser ablation of toluene liquid for surface micro-structuring of silica glass

    International Nuclear Information System (INIS)

    Niino, H.; Kawaguchi, Y.; Sato, T.; Narazaki, A.; Gumpenberger, T.; Kurosaki, R.

    2006-01-01

    Microstructures with well-defined micropatterns were fabricated on the surfaces of silica glass using a laser-induced backside wet etching (LIBWE) method by diode-pumped solid state (DPSS) UV laser at the repetition rate of 10 kHz. For a demonstration of flexible rapid prototyping as mask-less exposure system, the focused laser beam was directed to the sample by galvanometer-based point scanning system. Additionally, a diagnostics study of plume propagation in the ablated products of toluene solid film was carried out with an intensified CCD (ICCD) camera

  8. Different effects of silica added internal or external on in vitro dissolution of indomethacin hot-melt extrudates.

    Science.gov (United States)

    Xia, Yulong; Yuan, Meng; Deng, Yueyang; Ke, Xue; Ci, Tianyuan

    2017-12-20

    The purpose of this work was to investigate the effect on the dissolution behavior when silica was added in different ways. The solid dispersion was prepared by hot-melt extrusion (HME) using indomethacin (IND) as a model drug and Kollidon VA64 as a carrier. In order to change the dissolution behavior, the silica was added during or after the HME respectively, to obtain the corresponding silica internal-added solid dispersion (InSD) and silica external-added solid dispersion (ExSD). According to the results, the internal-added silicon dioxide could reduce the dissolution rate from 66.91%/h to 24.12%/h and the water infiltration rate from 0.37mm/h to 0.16mm/h in the phosphate buffer solution (PBS) of pH 6.8, so the formulation of InSD had a significant sustained release effect. But the infiltration rate of the ExSD was increased to 13.22mm/h when silica was added external, and the density of VA64 in the powder was decreased from 541.87mg/cm3 to 141.87mg/cm3, leading to a weak resistance to the external force, and the powder was easy to be dispersed after wetted by water so that the formulation of ExSD had a relatively higher dissolution rate. This phenomenon was more visible when the phosphate buffer solution was changed to pH 5.6 in which the API was more difficult to be dissolved. Accordingly, different addition ways of aerosil would change release behavior of the HME preparation. Copyright © 2017. Published by Elsevier B.V.

  9. Health hazards due to the inhalation of amorphous silica

    International Nuclear Information System (INIS)

    Merget, R.; Bruening, T.; Bauer, T.; Kuepper, H.U.; Breitstadt, R.; Philippou, S.; Bauer, H.D.

    2002-01-01

    Occupational exposure to crystalline silica dust is associated with an increased risk for pulmonary diseases such as silicosis, tuberculosis, chronic bronchitis, chronic obstructive pulmonary disease (COPD) and lung cancer. This review summarizes the current knowledge about the health effects of amorphous (non-crystalline) forms of silica. The major problem in the assessment of health effects of amorphous silica is its contamination with crystalline silica. This applies particularly to well-documented pneumoconiosis among diatomaceous earth workers. Intentionally manufactured synthetic amorphous silicas are without contamination of crystalline silica. These synthetic forms may be classified as (1) wet process silica, (2) pyrogenic (''thermal'' or ''fumed'') silica, and (3) chemically or physically modified silica. According to the different physico-chemical properties, the major classes of synthetic amorphous silica are used in a variety of products, e.g. as fillers in the rubber industry, in tyre compounds, as free-flow and anti-caking agents in powder materials, and as liquid carriers, particularly in the manufacture of animal feed and agrochemicals; other uses are found in toothpaste additives, paints, silicon rubber, insulation material, liquid systems in coatings, adhesives, printing inks, plastisol car undercoats, and cosmetics. Animal inhalation studies with intentionally manufactured synthetic amorphous silica showed at least partially reversible inflammation, granuloma formation and emphysema, but no progressive fibrosis of the lungs. Epidemiological studies do not support the hypothesis that amorphous silicas have any relevant potential to induce fibrosis in workers with high occupational exposure to these substances, although one study disclosed four cases with silicosis among subjects exposed to apparently non-contaminated amorphous silica. Since the data have been limited, a risk of chronic bronchitis, COPD or emphysema cannot be excluded. There is no

  10. Synthesis of silica nanosphere from homogeneous and ...

    Indian Academy of Sciences (India)

    WINTEC

    avoid it, reaction in heterogeneous system using CTABr was carried out. Nanosized silica sphere with ... Homogeneous system contains a mixture of ethanol, water, aqueous ammonia and ... heated to 823 K (rate, 1 K/min) in air and kept at this.

  11. Nanostructured Mesoporous Silicas for Bone Tissue Regeneration

    Directory of Open Access Journals (Sweden)

    Isabel Izquierdo-Barba

    2008-01-01

    Full Text Available The research on the development of new biomaterials that promote bone tissue regeneration is receiving great interest by the biomedical scientific community. Recent advances in nanotechnology have allowed the design of materials with nanostructure similar to that of natural bone. These materials can promote new bone formation by inducing the formation of nanocrystalline apatites analogous to the mineral phase of natural bone onto their surfaces, i.e. they are bioactive. They also stimulate osteoblast proliferation and differentiation and, therefore, accelerate the healing processes. Silica-based ordered mesoporous materials are excellent candidates to be used as third generation bioceramics that enable the adsorption and local control release of biological active agents that promote bone regeneration. This local delivery capability together with the bioactive behavior of mesoporous silicas opens up promising expectations in the bioclinical field. In this review, the last advances in nanochemistry aimed at designing and tailoring the chemical and textural properties of mesoporous silicas for biomedical applications are described. The recent developed strategies to synthesize bioactive glasses with ordered mesopore arrangements are also summarized. Finally, a deep discussion about the influence of the textural parameters and organic modification of mesoporous silicas on molecules adsorption and controlled release is performed.

  12. Mass transport in thin supported silica membranes

    NARCIS (Netherlands)

    Benes, Nieck Edwin

    2000-01-01

    In this thesis multi-component mass transport in thin supported amorphous silica membranes is discussed. These membranes are micro-porous, with pore diameters smaller than 4Å and show high fluxes for small molecules (such as hydrogen) combined with high selectivities for these molecules with respect

  13. Anisotropic silica mesostructures for DNA encapsulation

    Indian Academy of Sciences (India)

    The encapsulation of biomolecules in inert meso or nanostructures is an important step towards controlling drug delivery agents. Mesoporous silica nanoparticles (MSN) are of immense importance owing to their high surface area, large pore size, uniform particle size and chemical inertness. Reverse micellar method with ...

  14. Kinetics of silica-phase transitions

    International Nuclear Information System (INIS)

    Duffy, C.J.

    1993-07-01

    In addition to the stable silica polymorph quartz, several metastable silica phases are present in Yucca Mountain. The conversion of these phases to quartz is accompanied by volume reduction and a decrease in the aqueous silica activity, which may destabilize clinoptilolite and mordenite. The primary reaction sequence for the silica phases is from opal or glass to disordered opal-CT, followed by ordering of the opal-CT and finally by the crystallization of quartz. The ordering of opal-CT takes place in the solid state, whereas the conversion of opal-CT takes place through dissolution-reprecipitation involving the aqueous phase. It is proposed that the rate of conversion of opal-CT to quartz is controlled by diffusion of defects out of a disordered surface layer formed on the crystallizing quartz. The reaction rates are observed to be dependent on temperature, pressure, degree of supersaturation, and pH. Rate equations selected from the literature appear to be consistent with observations at Yucca Mountain

  15. Silica nanoparticles with a substrate switchable luminescence

    International Nuclear Information System (INIS)

    Bochkova, O D; Mustafina, A R; Fedorenko, S V; Konovalov, A I

    2011-01-01

    Silica nanoparticles with visible (Tb and Ru doped), near IR (Yb doped) and dual visible-near IR luminescence (Ru-Yb doped) were obtained by reverse w/o microemulsion procedure. Plenty of luminescent complexes (from 4900 to 10000) encapsulated into each nanoparticle ensures the intensive luminescence of nanoparticles and their applicability as biomarkers. The silica surface decoration by definite anchor groups is the required step for the gaining to these nanoparticles marking and sensing functions. Thus covalent and non-covalent surface modification of these nanoparticles was developed to provide the binding with biotargets and sensing of anions. The dicationic surfactant coating of negatively charged Tb(III)-TCAS doped silica nanoparticles was chosen as the basis for the anion responsible system. The reversible insertion of the quenching anions (namely phenol red) into the surfactant based layer at the surface of luminescent nanoparticles switches off the Tb-centered luminescence. In turn the reversible reestablishment of the luminescence results from the competitive insertion of the non-quenching anions into the surfactant layer at the silica/water interface. The hydrophobic anions exemplified by dodecylsulfates versus hydrophilic ones (hydrophosphates) are preferable in the competition with phenol red anions.

  16. Photo darkening of rare earth doped silica

    DEFF Research Database (Denmark)

    Mattsson, Kent Erik

    2011-01-01

    /2/11/2 chemical bond is formed on dioxasilirane which comprises the PD color center for the visible and near-infrared. Difference in solid acidity of the silica material co-doped with Yb/Al and Yb/P may explain the observed difference in spectral shapes by change of bond order to the formed chemical bond. © 2011...

  17. Silica gel matrix immobilized Chlorophyta hydrodictyon africanum ...

    African Journals Online (AJOL)

    Aghomotsegin

    2015-08-05

    Aug 5, 2015 ... The algae-silica gel adsorbent was used for batch sorption studies of a cationic dye, ... traditional methods of treating industrial effluent, these ... Author(s) agree that this article remains permanently open access under the terms of the Creative ... sodium silicate solution (v/v) and 25 mL of distilled water. With.

  18. Silica incorporated membrane for wastewater based filtration

    Science.gov (United States)

    Fernandes, C. S.; Bilad, M. R.; Nordin, N. A. H. M.

    2017-10-01

    Membrane technology has long been applied for waste water treatment industries due to its numerous advantages compared to other conventional processes. However, the biggest challenge in pressure driven membrane process is membrane fouling. Fouling decreases the productivity and efficiency of the filtration, reduces the lifespan of the membrane and reduces the overall efficiency of water treatment processes. In this study, a novel membrane material is developed for water filtration. The developed membrane incorporates silica nanoparticles mainly to improve its structural properties. Membranes with different loadings of silica nanoparticles were applied in this study. The result shows an increase in clean water permeability and filterability of the membrane for treating activated sludge, microalgae solution, secondary effluent and raw sewage as feed. Adding silica into the membrane matrix does not significantly alter contact angle and membrane pore size. We believe that silica acts as an effective pore forming agent that increases the number of pores without significantly altering the pore sizes. A higher number of small pores on the surface of the membrane could reduce membrane fouling because of a low specific loading imposed to individual pores.

  19. Investigation of fused silica dynamic behaviour

    International Nuclear Information System (INIS)

    Malaise, F.; Chevalier, J.M.; Bertron, I.; Malka, F.

    2006-01-01

    The survivability of the fused silica shields to shrapnel impacts is a key factor for the affordable operation of the intense laser irradiation future facility Laser Mega Joule (LMJ). This paper presents experimental data and computational modelling for LMJ fused silica upon shock wave loading and unloading. Gas-gun flyer plate impact and explosively driven tests have been conducted to investigate the dynamic behaviour of this material. Hugoniot states and the Hugoniot Elastic Limit of LMJ fused silica have been obtained. These experimental data are useful for determining some constitutive model constants of the 'Crack-Model', a continuum tensile and compressive failure model with friction based. This model has been improved by taking into account nonlinear elasticity. The numerical results obtained by performing computations of the previous tests and some ballistic impact tests are discussed. The numerical comparisons with the experimental data show good agreement. Further developments to simulate the permanent densification and the solid-to-solid phase transformation of fused silica are required. (authors)

  20. Cyclic olefin copolymer-silica nanocomposites foams

    Czech Academy of Sciences Publication Activity Database

    Pegoretti, A.; Dorigato, A.; Biani, A.; Šlouf, Miroslav

    2016-01-01

    Roč. 51, č. 8 (2016), s. 3907-3916 ISSN 0022-2461 R&D Projects: GA MŠk(CZ) LO1507 Institutional support: RVO:61389013 Keywords : cyclic olefin copolymer * nanocomposites * silica Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.599, year: 2016

  1. Fluorescence metrology of silica sol-gels

    Indian Academy of Sciences (India)

    We have developed a new method for measuring in-situ the growth of the nanometre-size silica particles which lead to the formation of sol-gel glasses. This technique is based on the decay of fluorescence polarisation anisotropy due to Brownian rotation of dye molecules bound to the particles. Results to date give near ...

  2. Facile method to fabricate raspberry-like particulate films for superhydrophobic surfaces.

    Science.gov (United States)

    Tsai, Hui-Jung; Lee, Yuh-Lang

    2007-12-04

    A facile method using layer-by-layer assembly of silica particles is proposed to prepare raspberry-like particulate films for the fabrication of superhydrophobic surfaces. Silica particles 0.5 microm in diameter were used to prepare a surface with a microscale roughness. Nanosized silica particles were then assembled on the particulate film to construct a finer structure on top of the coarse one. After surface modification with dodecyltrichlorosilane, the advancing and receding contact angles of water on the dual-sized structured surface were 169 and 165 degrees , respectively. The scale ratio of the micro/nano surface structure and the regularity of the particulate films on the superhydrophobic surface performance are discussed.

  3. Crystallization of biogenic hydrous amorphous silica

    Science.gov (United States)

    Kyono, A.; Yokooji, M.; Chiba, T.; Tamura, T.; Tuji, A.

    2017-12-01

    Diatom, Nitzschia cf. frustulum, collected from Lake Yogo, Siga prefecture, Japan was cultured in laboratory. Organic components of the diatom cell were removed by washing with acetone and sodium hypochlorite. The remaining frustules were studied by SEM-EDX, FTIR spectroscopy, and synchrotron X-ray diffraction. The results showed that the spindle-shaped morphology of diatom frustule was composed of hydrous amorphous silica. Pressure induced phase transformation of the diatom frustule was investigated by in situ Raman spectroscopic analysis. With exposure to 0.3 GPa at 100 oC, Raman band corresponding to quartz occurred at ν = 465 cm-1. In addition, Raman bands known as a characteristic Raman pattern of moganite was also observed at 501 cm-1. From the integral ratio of Raman bands, the moganite content in the probed area was estimated to be approximately 50 wt%. With the pressure and temperature effect, the initial morphology of diatom frustule was completely lost and totally changed to a characteristic spherical particle with a diameter of about 2 mm. With keeping the compression of 5.7 GPa at 100 oC, a Raman band assignable to coesite appeared at 538 cm-1. That is, with the compression and heating, the hydrous amorphous silica can be readily crystallized into quartz, moganite, and coesite. The first-principles calculations revealed that a disiloxane molecule stabilized in a trans configuration is twisted 60o and changed into the cis configuration with a close approach of water molecule. It is therefore a reasonable assumption that during crystallization of hydrous amorphous silica, the Si-O-Si bridging unit with the cis configuration would survive as a structural defect and then crystallized into moganite by keeping the geometry. This hypothesis is adaptable to the phase transformation from hydrous amorphous silica to coesite as well, because coesite has the four-membered rings and easily formed from the hydrous amorphous silica under high pressure and high

  4. Curcumin nanodisks: formulation and characterization

    OpenAIRE

    Ghosh, Mistuni; Singh, Amareshwar T. K.; Xu, Wenwei; Sulchek, Todd; Gordon, Leo I.; Ryan, Robert O.

    2010-01-01

    Nanodisks (ND) are nanoscale, disk-shaped phospholipid bilayers whose edge is stabilized by apolipoproteins. In the present study, ND were formulated with the bioactive polyphenol, curcumin, at a 6:1 phospholipid:curcumin molar ratio. Atomic force microscopy revealed that curcumin-ND are particles with diameters

  5. Covariant Formulation of Hooke's Law.

    Science.gov (United States)

    Gron, O.

    1981-01-01

    Introducing a four-vector strain and a four-force stress, Hooke's law is written as a four-vector equation. This formulation is shown to clarify seemingly paradoxical results in connection with uniformly accelerated motion, and rotational motion with angular acceleration. (Author/JN)

  6. Hamiltonian formulation of the supermembrane

    International Nuclear Information System (INIS)

    Bergshoeff, E.; Sezgin, E.; Tanii, Y.

    1987-06-01

    The Hamiltonian formulation of the supermembrane theory in eleven dimensions is given. The covariant split of the first and second class constraints is exhibited, and their Dirac brackets are computed. Gauge conditions are imposed in such a way that the reparametrizations of the membrane with divergence free 2-vectors are unfixed. (author). 10 refs

  7. Improved antimicrobial property and controlled drug release kinetics of silver sulfadiazine loaded ordered mesoporous silica

    Directory of Open Access Journals (Sweden)

    Suman Jangra

    2016-09-01

    Full Text Available The present study deals with the loading of silver sulfadiazine into ordered mesoporous silica material by post-impregnation method and its effect on the in vitro release kinetics and antimicrobial property of the drug. The formulated SBA-15 silica material with rope-like morphology and SBA-15-silver sulfadiazine (SBA-AgSD were characterized by UV–visible spectrophotometer, small and wide-angle powder X-ray diffraction (PXRD, field emission scanning electron microscope (FESEM and high resolution transmission electron microscope (HRTEM. Thermo-gravimetric analysis of SBA-AgSD revealed a high loading amount of 52.87%. Nitrogen adsorption–desorption analysis confirmed the drug entrapment into host material by revealing a reduced surface area (214 m2/g and pore diameter (6.7 nm of the SBA-AgSD. The controlled release of silver sulfadiazine drug from the mesoporous silica to simulated gastric, intestinal and body fluids was evaluated. The Korsmeyer–Peppas model fits the drug release data with the non-Fickian diffusion model and zero order kinetics of SBA-AgSD. The antibacterial performance of the SBA-AgSD was evaluated with respect to Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa. The controlled drug delivery of the SBA-AgSD revealed improved antibacterial activity, thus endorsing its applicability in effective wound dressing.

  8. Preparation of resveratrol-loaded nanoporous silica materials with different structures

    Energy Technology Data Exchange (ETDEWEB)

    Popova, Margarita, E-mail: mpopova@orgchem.bas.bg [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Szegedi, Agnes [Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Hungarian Academy of Sciences, 1117 Budapest, Magyar tudósok körútja 2. (Hungary); Mavrodinova, Vesselina [Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria); Novak Tušar, Natasa [National Institute of Chemistry, Ljubljana (Slovenia); Mihály, Judith; Klébert, Szilvia [Research Centre for Natural Sciences, Institute of Materials and Environmental Chemistry, Hungarian Academy of Sciences, 1117 Budapest, Magyar tudósok körútja 2. (Hungary); Benbassat, Niko; Yoncheva, Krassimira [Faculty of Pharmacy, 2 Dunav Str., 1000 Sofia (Bulgaria)

    2014-11-15

    Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated. Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound. - Graphical abstract: trans-Resveratrol was stabilized in the pores of BEA zeolite, MCM-41and KIL2 mesoporous silicas. - Highlights: • BEA, KIL-2 and MCM-41 materials were used as carriers for resveratrol loading. • Resveratrol encapsulation in ethanol solution and solid state procedure were applied. • The solid-state preparation appears very effective for stabilization of trans-resveratrol.

  9. Preparation of resveratrol-loaded nanoporous silica materials with different structures

    International Nuclear Information System (INIS)

    Popova, Margarita; Szegedi, Agnes; Mavrodinova, Vesselina; Novak Tušar, Natasa; Mihály, Judith; Klébert, Szilvia; Benbassat, Niko; Yoncheva, Krassimira

    2014-01-01

    Solid, nanoporous silica-based spherical mesoporous MCM-41 and KIL-2 with interparticle mesoporosity as well as nanosized zeolite BEA materials differing in morphology and pore size distribution, were used as carriers for the preparation of resveratrol-loaded delivery systems. Two preparation methods have been applied: (i) loading by mixing of resveratrol and mesoporous carrier in solid state and (ii) deposition in ethanol solution. The parent and the resveratrol loaded carriers were characterized by XRD, TEM, N2 physisorption, thermal analysis, and FT-IR spectroscopy. The influence of the support structure on the adsorption capacity and the release kinetics of this poorly soluble compound were investigated. Our results indicated that the chosen nanoporous silica supports are suitable for stabilization of trans-resveratrol and reveal controlled release and ability to protect the supported compound against degradation regardless of loading method. The solid-state dry mixing appears very effective for preparation of drug formulations composed of poorly soluble compound. - Graphical abstract: trans-Resveratrol was stabilized in the pores of BEA zeolite, MCM-41and KIL2 mesoporous silicas. - Highlights: • BEA, KIL-2 and MCM-41 materials were used as carriers for resveratrol loading. • Resveratrol encapsulation in ethanol solution and solid state procedure were applied. • The solid-state preparation appears very effective for stabilization of trans-resveratrol

  10. Potential of nanoparticles for allergen-specific immunotherapy - use of silica nanoparticles as vaccination platform.

    Science.gov (United States)

    Scheiblhofer, Sandra; Machado, Yoan; Feinle, Andrea; Thalhamer, Josef; Hüsing, Nicola; Weiss, Richard

    2016-12-01

    Allergen-specific immunotherapy is the only curative approach for the treatment of allergies. There is an urgent need for improved therapies, which increase both, efficacy and patient compliance. Novel routes of immunization and the use of more advanced vaccine platforms have gained heightened interest in this field. Areas covered: The current status of allergen-specific immunotherapy is summarized and novel routes of immunization and their challenges in the clinics are critically discussed. The use of nanoparticles as novel delivery system for allergy vaccines is comprehensively reviewed. Specifically, the advantages of silica nanoparticles as vaccine carriers and adjuvants are summarized. Expert opinion: Future allergen-specific immunotherapy will combine engineered hypoallergenic vaccines with novel routes of administration, such as the skin. Due to their biodegradability, and the easiness to introduce surface modifications, silica nanoparticles are promising candidates for tailor-made vaccines. By covalently linking allergens and polysaccharides to silica nanoparticles, a versatile vaccination platform can be designed to specifically target antigen-presenting cells, render the formulation hypoallergenic, and introduce immunomodulatory functions. Combining potent skin vaccination methods, such as fractional laser ablation, with nanoparticle-based vaccines addresses all the requirements for safe and efficient therapy of allergic diseases.

  11. Development of vapor deposited silica sol-gel particles for use as a bioactive materials system.

    Science.gov (United States)

    Snyder, Katherine L; Holmes, Hallie R; VanWagner, Michael J; Hartman, Natalie J; Rajachar, Rupak M

    2013-06-01

    Silica-based sol-gel and bioglass materials are used in a variety of biomedical applications including the surface modification of orthopedic implants and tissue engineering scaffolds. In this work, a simple system for vapor depositing silica sol-gel nano- and micro-particles onto substrates using nebulizer technology has been developed and characterized. Particle morphology, size distribution, and degradation can easily be controlled through key formulation and manufacturing parameters including water:alkoxide molar ratio, pH, deposition time, and substrate character. These particles can be used as a means to rapidly modify substrate surface properties, including surface hydrophobicity (contact angle changes >15°) and roughness (RMS roughness changes of up to 300 nm), creating unique surface topography. Ions (calcium and phosphate) were successfully incorporated into particles, and induced apatitie-like mineral formation upon exposure to simulated body fluid Preosteoblasts (MC3T3) cultured with these particles showed up to twice the adhesivity within 48 h when compared to controls, potentially indicating an increase in cell proliferation, with the effect likely due to both the modified substrate properties as well as the release of silica ions. This novel method has the potential to be used with implants and tissue engineering materials to influence cell behavior including attachment, proliferation, and differentiation via cell-material interactions to promote osteogenesis. Copyright © 2012 Wiley Periodicals, Inc.

  12. Encapsulation of antigen-loaded silica nanoparticles into microparticles for intradermal powder injection.

    Science.gov (United States)

    Deng, Yibin; Mathaes, Roman; Winter, Gerhard; Engert, Julia

    2014-10-15

    Epidermal powder immunisation (EPI) is being investigated as a promising needle-free delivery methods for vaccination. The objective of this work was to prepare a nanoparticles-in-microparticles (nano-in-micro) system, integrating the advantages of nanoparticles and microparticles into one vaccine delivery system for epidermal powder immunisation. Cationic mesoporous silica nanoparticles (MSNP-NH2) were prepared and loaded with ovalbumin as a model antigen. Loading was driven by electrostatic interactions. Ovalbumin-loaded silica nanoparticles were subsequently formulated into sugar-based microparticles by spray-freeze-drying. The obtained microparticles meet the size requirement for EPI. Confocal microscopy was used to demonstrate that the nanoparticles are homogeneously distributed in the microparticles. Furthermore, the silica nanoparticles in the dry microparticles can be re-dispersed in aqueous solution showing no aggregation. The recovered ovalbumin shows integrity compared to native ovalbumin. The present nano-in-micro system allows (1) nanoparticles to be immobilized and finely distributed in microparticles, (2) microparticle formation and (3) re-dispersion of nanoparticles without subsequent aggregation. The nanoparticles inside microparticles can (1) adsorb proteins to cationic shell/surface voids in spray-dried products without detriment to ovalbumin stability, (2) deliver antigens in nano-sized modes to allow recognition by the immune system. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Effect of the Silica Content of Diatoms on Protozoan Grazing

    Directory of Open Access Journals (Sweden)

    Shuwen Zhang

    2017-06-01

    Full Text Available This study examined the effect that silica content in diatom cells has on the behavior of protists. The diatoms Thalassiosira weissflogii and T. pseudonana were cultured in high or low light conditions to achieve low and high silica contents, respectively. These cells were then fed to a heterotrophic dinoflagellate Noctiluca scintillans and a ciliate Euplotes sp. in single and mixed diet experiments. Our results showed that in general, N. scintillans and Euplotes sp. both preferentially ingested the diatoms with a low silica content rather than those with a high silica content. However, Euplotes sp. seemed to be less influenced by the silica content than was N. scintillans. In the latter case, the clearance and ingestion rate of the low silica diatoms were significantly higher, both in the short (6-h and long (1-d duration grazing experiments. Our results also showed that N. scintillans required more time to digest the high silica-containing cells. As the high silica diatoms are harder to digest, this might explain why N. scintillans exhibits a strong preference for the low silica prey. Thus, the presence of high silica diatoms might limit the ability of the dinoflagellate to feed. Our findings suggest that the silica content of diatoms affects their palatability and digestibility and, consequently, the grazing activity and selectivity of protozoan grazers.

  14. Effect of silica particle size on macrophage inflammatory responses.

    Directory of Open Access Journals (Sweden)

    Toshimasa Kusaka

    Full Text Available Amorphous silica particles, such as nanoparticles (<100 nm diameter particles, are used in a wide variety of products, including pharmaceuticals, paints, cosmetics, and food. Nevertheless, the immunotoxicity of these particles and the relationship between silica particle size and pro-inflammatory activity are not fully understood. In this study, we addressed the relationship between the size of amorphous silica (particle dose, diameter, number, and surface area and the inflammatory activity (macrophage phagocytosis, inflammasome activation, IL-1β secretion, cell death and lung inflammation. Irrespective of diameter size, silica particles were efficiently internalized by mouse bone marrow-derived macrophages via an actin cytoskeleton-dependent pathway, and induced caspase-1, but not caspase-11, activation. Of note, 30 nm-1000 nm diameter silica particles induced lysosomal destabilization, cell death, and IL-1β secretion at markedly higher levels than did 3000 nm-10000 nm silica particles. Consistent with in vitro results, intra-tracheal administration of 30 nm silica particles into mice caused more severe lung inflammation than that of 3000 nm silica particles, as assessed by measurement of pro-inflammatory cytokines and neutrophil infiltration in bronchoalveolar lavage fluid of mice, and by the micro-computed tomography analysis. Taken together, these results suggest that silica particle size impacts immune responses, with submicron amorphous silica particles inducing higher inflammatory responses than silica particles over 1000 nm in size, which is ascribed not only to their ability to induce caspase-1 activation but also to their cytotoxicity.

  15. Converting Water Adsorption and Capillary Condensation in Usable Forces with Simple Porous Inorganic Thin Films.

    Science.gov (United States)

    Boudot, Mickael; Elettro, Hervé; Grosso, David

    2016-11-22

    This work reports an innovative humidity-driven actuation concept based on conversion of chemical energy of adsorption/desorption using simple nanoporous sol-gel silica thin films as humidity-responsive materials. Bilayer-shaped actuators, consisting of a humidity-sensitive active nanostructured silica film deposited on a polymeric substrate (Kapton), were demonstrated as an original mean to convert water molecule adsorption and capillary condensation in usable mechanical work. Reversible solvation stress changes in silica micropores by water adsorption and energy produced by the rigid silica film contraction, induced by water capillary condensation in mesopores, were finely controlled and used as energy sources. The influence of the film nanostructure (microporosity, mesoporosity) and thickness and the polymeric substrate thickness on actuation force, on movement speed and on displacement amplitude are clearly evidenced and discussed. We show that the global mechanical response of such silica-based actuators can easily be adjusted to fabricate tailor-made actuation systems triggered by humidity variation. This study provides insight into hard ceramic stimulus-responsive materials that seem to be a promising alternative to traditional soft organic materials for surface-chemistry-driven actuation systems.

  16. Film processing

    International Nuclear Information System (INIS)

    Abdul Nassir Ibrahim; Azali Muhammad; Ab. Razak Hamzah; Abd. Aziz Mohamed; Mohamad Pauzi Ismail

    2008-01-01

    The processing was made not only to show what are in the film but also to produce radiograph with high quality where the information gathered really presented level of the quality of the object inspected. Besides that, good procedure will make the film with good quality can keep the film in long time for reference. Here, more detailed on how the dark room functioned and its design. So, the good procedure while processed the film will be discussed detailed in this chapter from entering the dark room to exit from there.

  17. Demens Film

    DEFF Research Database (Denmark)

    Jensen, Anders Møller

    2012-01-01

    Vi vil skabe film til mennesker med demens – ikke film om demens sygdommen eller beretninger om livet og hverdagen med en kronisk lidelse. Filmene skal medvirke til at frembringe en behagelig stemning omkring og hos mennesker med demens, så hverdagen bliver så tryg som mulig. Filmene skal samtidig...... var at afgrænse og prioritere projektet, samt komme med anbefalinger omkring hvad der er vigtigt, i forbindelse med produktion af film målrettet mennesker med demens. Resultat af ekspertgruppen sammenfattes i denne rapport. Projektet gennemføres som et samarbejde mellem Retrospect Film...

  18. Formulation and process considerations affecting the stability of solid dosage forms formulated with methacrylate copolymers.

    Science.gov (United States)

    Petereit, H U; Weisbrod, W

    1999-01-01

    General considerations concerning the stability of coated dosage forms are discussed, in order to avoid predictable interactions which may cause long-term stability problems. As polymers themselves maintain a high chemical stability and a low reactivity, instability phenomena mainly have to be explained by interactions of low molecular weight substances or physical changes. Possible interactions of functional groups can be predicted easily and insulating subcoates are proper countermeasures. Impurities, remaining in the polymeric material from the manufacturing process, may accelerate the hydrolysis of sensitive drugs. Instabilities of coated dosage forms are mainly based on physical interactions, caused by improper formulations of coating suspensions (i.e. plasticizers or pigments) or the film coating process. Residual moisture or solvents, probably enclosed in the core and migrating over time, may increase the permeability of coatings, due to plasticizing effects. The functionality of coatings from aqueous dispersions is linked to coalescence of latex particles. Thus any incomplete film formation, caused by too high or too low coating temperatures, may result in high permeable coatings. During storage, preferably under stress conditions this process will continue and thus change the release profile. Therefore bed temperatures of 10-20 degrees C above MFT must ensure the formation of homogeneous polymer layers during the coating process. Stability test procedures and packaging materials also need to be adapted to the physicochemical properties of the dosage form, in order to get meaningful results in stability tests.

  19. Influence of polymer matrix and adsorption onto silica materials on the migration of alpha-tocopherol into 95% ethanol from active packaging.

    Science.gov (United States)

    Heirlings, L; Siró, I; Devlieghere, F; Van Bavel, E; Cool, P; De Meulenaer, B; Vansant, E F; Debevere, J

    2004-11-01

    In this study, the effect of polymer materials with different polarity, namely low density polyethylene (LDPE) and ethylene vinyl acetate (EVA), on the migration behaviour of alpha-tocopherol from active packaging was investigated. The antioxidant was also adsorbed onto silica materials, namely SBA-15 (Santa Barbara-15) and Syloblock, in order to protect the antioxidant during extrusion and to ensure a controlled and sufficient release during the shelf-life of the food product. Migration experiments were performed at 7.0 +/- 0.5 degrees C and 95% ethanol was used as fatty food simulant. All films contained a high concentration of alpha-tocopherol, approximately 2000 mg kg(-1), to obtain an active packaging. Polymer matrix had a small influence on the migration profile. The migration of 80% of total migrated amount of antioxidant was retarded for 2.4 days by using LDPE instead of EVA. When alpha-tocopherol was adsorbed onto both silica materials, the migration of 80% of total migrated amount of antioxidant was retarded for 3.4 days in comparison to pure alpha-tocopherol. No difference was seen between the migration profiles of alpha-tocopherol adsorbed onto both silica materials. In the case of pure alpha-tocopherol, 82% of the initial amount of alpha-tocopherol in the film migrated into the food simulant at a rather fast migration rate. In the case of adsorption on silica materials, a total migration was observed. These antioxidative films can have positive food applications.

  20. Surfactant mediated slurry formulations for Ge CMP applications

    KAUST Repository

    Basim, G. Bahar

    2013-01-01

    In this study, slurry formulations in the presence of self-assembled surfactant structures were investigated for Ge/SiO2 CMP applications in the absence and presence of oxidizers. Both anionic (sodium dodecyl sulfate-SDS) and cationic (cetyl trimethyl ammonium bromide-C12TAB) micelles were used in the slurry formulations as a function of pH and oxidizer concentration. CMP performances of Ge and SiO2 wafers were evaluated in terms of material removal rates, selectivity and surface quality. The material removal rate responses were also assessed through AFM wear rate tests to obtain a faster response for preliminary analyses. The surfactant adsorption characteristics were studied through surface wettability responses of the Ge and SiO2 wafers through contact angle measurements. It was observed that the self-assembled surfactant structures can help obtain selectivity on the silica/germanium system at low concentrations of the oxidizer in the slurry. © 2013 Materials Research Society.

  1. Characterization of a silica-PVA hybrid for high density and stable silver dissolution

    Energy Technology Data Exchange (ETDEWEB)

    Dorin, Bryce, E-mail: bryce.dorin@postgrad.manchester.ac.uk [The Photon Science Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); School of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Zhu, Guangyu, E-mail: g.zhu@liverpool.ac.uk [Lairdside Laser Engineering Centre, The University of Liverpool, Campbeltown Road, Merseyside, CH41 9HP (United Kingdom); Parkinson, Patrick, E-mail: patrick.parkinson@manchester.ac.uk [The Photon Science Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Perrie, Walter, E-mail: wpfemto1@liverpool.ac.uk [Lairdside Laser Engineering Centre, The University of Liverpool, Campbeltown Road, Merseyside, CH41 9HP (United Kingdom); Benyezzar, Med, E-mail: med.benyezzar@manchester.ac.uk [The Photon Science Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Scully, Patricia, E-mail: patricia.scully@manchester.ac.uk [The Photon Science Institute, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); School of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom)

    2016-07-01

    A silica and polyvinyl alcohol (PVA) hybrid material mixed with a high density of silver ions is synthesised and characterized in this work. The hybrid material can be cast into thick films, which we determined to be homogeneous using Raman spectroscopy. We observed that the silver ions remain stable in the material over time and at temperatures of 100 °C, which represents a marked improvement over previous solid solutions of silver. Differential scanning calorimetry and thermogravimetric analysis indicate the rapid activation of silver at 173 °C, resulting in a dense formation of silver nanoparticles within the hybrid. The activation of silver was also demonstrated in 3-dimensional geometries using femtosecond duration laser pulses. These results illustrate the silica-PVA hybrid is an attractive material for developing silver-insulator composites. - Highlights: • A novel PVA-silica hybrid is developed for silver ion dissolution. • The hybrid exhibits a high silver saturation point and good silver stability. • Heating and laser irradiation are capable of converting the silver ions to metal. • The hybrid material enables the fabrication of 3D metal-insulator composites.

  2. Arrays of Hollow Silica Half-Nanospheres Via the Breath Figure Approach

    KAUST Repository

    Gao, Yangqin; Hou, Yuanfang; Beaujuge, Pierre

    2015-01-01

    Breath figures (BFs) are patterns of liquid droplets that usually form upon condensation on a cold surface. Earlier work has shown that BFs can be used to produce continuous films of porous honeycomb-structured patterns on various types of materials, paving the path to a number of important applications such as the manufacturing of highly ordered nano- and micron-sized templates, micro lenses, and superhydrophobic coatings. It is worth noting, however, that few new findings have been reported in this area in recent years, limiting pursuits of novel architectures and key applications. In this report, an alternative method is described by which arrays of hollow silica half-nanospheres can be produced via BF templates. In the present method, a chemical vapor deposition (CVD) protocol performed while the BF is formed on a glass substrate yields a nanostructured pattern of silica half-spheres, which size (100-700 nm) and density across the glass surface vary with substrate modification and with the relative rates of water condensation and hydrolysis from silica precursors (a process carried out at room temperature). This method of forming arrays of hollow half-nanospheres via the BF approach may be applicable to various other oxides and a broad range of substrates including large-area flexible plastics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Wideband two-port beam splitter of a binary fused-silica phase grating.

    Science.gov (United States)

    Wang, Bo; Zhou, Changhe; Feng, Jijun; Ru, Huayi; Zheng, Jiangjun

    2008-08-01

    The usual beam splitter of multilayer-coated film with a wideband spectrum is not easy to achieve. We describe the realization of a wideband transmission two-port beam splitter based on a binary fused-silica phase grating. To achieve high efficiency and equality in the diffracted 0th and -1st orders, the grating profile parameters are optimized using rigorous coupled-wave analysis at a wavelength of 1550 nm. Holographic recording and the inductively coupled plasma dry etching technique are used to fabricate the fused-silica beam splitter grating. The measured efficiency of (45% x 2) = 90% diffracted into the both orders can be obtained with the fabricated grating under Littrow mounting. The physical mechanism of such a wideband two-port beam splitter grating can be well explained by the modal method based on two-beam interference of the modes excited by the incident wave. With the high damage threshold, low coefficient of thermal expansion, and wideband high efficiency, the presented beam splitter etched in fused silica should be a useful optical element for a variety of practical applications.

  4. Arrays of Hollow Silica Half-Nanospheres Via the Breath Figure Approach

    KAUST Repository

    Gao, Yangqin

    2015-04-21

    Breath figures (BFs) are patterns of liquid droplets that usually form upon condensation on a cold surface. Earlier work has shown that BFs can be used to produce continuous films of porous honeycomb-structured patterns on various types of materials, paving the path to a number of important applications such as the manufacturing of highly ordered nano- and micron-sized templates, micro lenses, and superhydrophobic coatings. It is worth noting, however, that few new findings have been reported in this area in recent years, limiting pursuits of novel architectures and key applications. In this report, an alternative method is described by which arrays of hollow silica half-nanospheres can be produced via BF templates. In the present method, a chemical vapor deposition (CVD) protocol performed while the BF is formed on a glass substrate yields a nanostructured pattern of silica half-spheres, which size (100-700 nm) and density across the glass surface vary with substrate modification and with the relative rates of water condensation and hydrolysis from silica precursors (a process carried out at room temperature). This method of forming arrays of hollow half-nanospheres via the BF approach may be applicable to various other oxides and a broad range of substrates including large-area flexible plastics. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Boiling of water in flow restricted areas modeled by colloidal silica deposits

    International Nuclear Information System (INIS)

    Peixinho, Jorge; Lefevre, Gregory; Coudert, Francois-Xavier; Hurisse, Olivier

    2012-09-01

    Understanding the effects of particle deposits on evaporation and boiling of water represents an important issue for EDF because it causes a severe reduction in efficiency particularly in steam generators of pressurized water reactor. These deposits are made of oxide metallic particles and the deposition process depends on multiple factors. Here we mimic deposits using a simple system made of hydrophilic silica particles. The present study reports experiments on evaporation or boiling of water confined in the pores of colloidal mono-dispersed silica micro-sphere deposits. The boiling of water confined in the pores of the colloidal crystal is studied using optical microscopy, scanning electron microscopy, nitrogen adsorption, water adsorption through infrared attenuated total reflectance spectroscopy, differential scanning calorimetry and thermal gravimetric analysis. By comparison of the results with silica deposits and alumina membranes with cylindrical pores, our study shows that the morphology of the pores contributes to the evaporation and boiling of water. The measurements suggest that particle resuspension and crust formation take place during drying at elevated temperature and are responsible for cracks formation within the deposit film. (authors)

  6. Silica fractionation and reactivity in soils

    Science.gov (United States)

    Unzué Belmonte, Dácil; Barão, Lúcia; Vandevenne, Floor; Schoelynck, Jonas; Struyf, Eric; Meire, Patrick

    2014-05-01

    The Si cycle is a globally important biogeochemical cycle, with strong connections to other biogeochemical cycles, including C. Silica is taken up by plants to form protective structures called phytoliths, which become a part of the soil and contribute strongly to soil Si cycling upon litter burial. Different silica fractions are found in soils, with phytoliths among the most easily soluble, especially compared to silicate minerals. A whole set of secondary non-biogenic fractions exist, that also have a high reactivity (adsorbed Si, reactive secondary minerals…). A good characterization of the different fractions of reactive silica is crucial to move forward knowledge on ecosystem Si cycling, which has been recognized in the last decade as crucial for terrestrial Si fluxes. A new method to analyze the different fractions of silica in soils has been described by Koning et al. (2002) and adapted by our research team (Barão et al. 2013). Using a continuous extraction of Si and aluminum in 0.5M NaOH, biogenic and non-biogenic reactive fractions are separated based on their Si/Al ratios and their reactivity in NaOH. Applying this new method I will investigate three emerging ideas on how humans can affect directly terrestrial Si fluxes. -Land use. I expect strong silica fractionation and reactivity differences in different land uses. These effects due to agricultural and forestry management have already been shown earlier in temperate soils (Vandevenne et al. 2012). Now we will test this hypothesis in recently deforested soils, in the south of Brazil. 'Pristine' forest, managed forest and tobacco field soils (with and without rotation crops) will be studied. This research belongs to an interdisciplinary project on soils and global change. -Fire. According to the IPCC report, extreme events such as fires (number and intensity) would increase due to climate change. We analyzed litter from spruce forest, beech forest and peat soils at two burning levels, after 350°C and

  7. Effect of formulation compositions on niosomal preparations.

    Science.gov (United States)

    Chaw, Cheng Shu; Kim, Kwong Yioung Ah

    2013-01-01

    This study was aimed to investigate the effects of molar ratio of cholesterol to Span 60 and stabilizers (Solutol HS 15 or dicetyl phosphate (DCP)) on the entrapment of methylene blue, a model hydrophilic drug. The niosomes were prepared by the film hydration method and characterized for drug entrapment efficiency (EE), vesicle size, zeta potential and thermal properties of niosomal membrane. It was found that niosomal vesicles possessed median diameter ranging from 0.35 to 1.85 μm. The niosomes that were formulated with lower molar ratios of cholesterol to Span 60 of 0.33 and 0.50 produced significantly higher EE with both stabilizers when compared to cholesterol to Span 60 molar ratios of 1.0 and above (p Solutol HS 15 except at a molar ratio of cholesterol to Span 60 of 0.33. In conclusion, with low molar ratios of cholesterol to Span 60, more drugs could be entrapped within the niosomes regardless of the type of stabilizers. Furthermore, EE and median diameter of niosomes containing DCP were higher than those stabilized with Solutol HS 15.

  8. Spectroscopy of nanosized composites silicon-organic polymer/nanoporous silicas

    International Nuclear Information System (INIS)

    Ostapenko, N.; Kozlova, N.; Suto, S.; Watanabe, A.

    2006-01-01

    Fluorescence and excitation spectra (T=5-290 K) of nanosized silicon-organic polymers poly(di-n-hexylsilane) and poly(methyl(phenyl)silane) incorporated into porous silica materials MCM-41 and SBA-15 have been studied with varying pore diameter from 2.8 to 10 nm. The controlled variation of the pore diameter in a wide range (2.8-10 nm) permitted us, for the first time, to investigate the optical properties of the polymers on their transition from isolated macromolecules to a film. It is found that this transition depends on polymer type and occurs via the formation of new spatially independent structures of the polymers not observed in the spectra of the film, namely, via the formation of disordered and (or) ordered conformations of polymer chains and clusters

  9. Curcumin and its topical formulations for wound healing applications.

    Science.gov (United States)

    Mohanty, Chandana; Sahoo, Sanjeeb K

    2017-10-01

    Oxidative damage and inflammation have been identified, through clinical and preclinical studies, as the main causes of nonhealing chronic wounds. Reduction of persistent chronic inflammation by application of antioxidant and anti-inflammatory agents such as curcumin has been well studied. However, low aqueous solubility, poor tissue absorption, rapid metabolism and short plasma half-life have made curcumin unsuitable for systemic administration for better wound healing. Recently, various topical formulations of curcumin such as films, fibers, emulsion, hydrogels and different nanoformulations have been developed for targeted delivery of curcumin at wounded sites. In this review, we summarize and discuss different topical formulations of curcumin with emphasis on their wound-healing properties in animal models. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Thiolated Chitosan Masked Polymeric Microspheres with Incorporated Mesocellular Silica Foam (MCF for Intranasal Delivery of Paliperidone

    Directory of Open Access Journals (Sweden)

    Stavroula Nanaki

    2017-11-01

    Full Text Available In this study, mesocellular silica foam (MCF was used to encapsulate paliperidone, an antipsychotic drug used in patients suffering from bipolar disorder. MCF with the drug adsorbed was further encapsulated into poly(lactic acid (PLA and poly(lactide-co-glycolide (PLGA 75/25 w/w microspheres and these have been coated with thiolated chitosan. As found by TEM analysis, thiolated chitosan formed a thin layer on the polymeric microspheres’ surface and was used in order to enhance their mucoadhesiveness. These microspheres aimed at the intranasal delivery of paliperidone. The DSC and XRD studies showed that paliperidone was encapsulated in amorphous form inside the MCF silica and for this reason its dissolution profile was enhanced compared to the neat drug. In coated microspheres, thiolated chitosan reduced the initial burst effect of the paliperidone dissolution profile and in all cases sustained release formulations have been prepared. The release mechanism was also theoretically studied and three kinetic models were proposed and successfully fitted for a dissolution profile of prepared formulations to be found.

  11. Development of gellan gum containing formulations for transdermal drug delivery: Component evaluation and controlled drug release using temperature responsive nanogels.

    Science.gov (United States)

    Carmona-Moran, Carlos A; Zavgorodnya, Oleksandra; Penman, Andrew D; Kharlampieva, Eugenia; Bridges, S Louis; Hergenrother, Robert W; Singh, Jasvinder A; Wick, Timothy M

    2016-07-25

    Enhancing skin permeation is important for development of new transdermal drug delivery formulations. This is particularly relevant for non-steroidal anti-inflammatory drugs (NSAIDs). To address this, semisolid gel and solid hydrogel film formulations containing gellan gum as a gelling agent were developed and the effects of penetration enhancers (dimethyl sulfoxide, isopropyl alcohol and propylene glycol) on transport of the NSAID diclofenac sodium was quantified. A transwell diffusion system was used to accelerate formulation development. After 4h, diclofenac flux from a superior formulation of the semisolid gel or the solid hydrogel film was 130±11μg/cm(2)h and 108±7μg/cm(2)h, respectively, and significantly greater than that measured for a currently available diclofenac sodium topical gel (30±4μg/cm(2)h, ptransdermal drug formulations with adjustable drug transport kinetics. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. thin films

    Indian Academy of Sciences (India)

    microscopy (SEM) studies, respectively. The Fourier transform ... Thin films; chemical synthesis; hydrous tin oxide; FTIR; electrical properties. 1. Introduction ... dehydrogenation of organic compounds (Hattori et al 1987). .... SEM images of (a) bare stainless steel and (b) SnO2:H2O thin film on stainless steel substrate at a ...

  13. Into films

    DEFF Research Database (Denmark)

    Tan, Ed S.; Doicaru, Miruna M.; Hakemulder, Frank

    2017-01-01

    Most film viewers know the experience of being deeply absorbed in the story of a popular film. It seems that at such moments they lose awareness of watching a movie. And yet it is highly unlikely that they completely ignore the fact that they watch a narrative and technological construction. Perh...

  14. Plasma polymer-functionalized silica particles for heavy metals removal.

    Science.gov (United States)

    Akhavan, Behnam; Jarvis, Karyn; Majewski, Peter

    2015-02-25

    Highly negatively charged particles were fabricated via an innovative plasma-assisted approach for the removal of heavy metal ions. Thiophene plasma polymerization was used to deposit sulfur-rich films onto silica particles followed by the introduction of oxidized sulfur functionalities, such as sulfonate and sulfonic acid, via water-plasma treatments. Surface chemistry analyses were conducted by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy. Electrokinetic measurements quantified the zeta potentials and isoelectric points (IEPs) of modified particles and indicated significant decreases of zeta potentials and IEPs upon plasma modification of particles. Plasma polymerized thiophene-coated particles treated with water plasma for 10 min exhibited an IEP of less than 3.5. The effectiveness of developed surfaces in the adsorption of heavy metal ions was demonstrated through copper (Cu) and zinc (Zn) removal experiments. The removal of metal ions was examined through changing initial pH of solution, removal time, and mass of particles. Increasing the water plasma treatment time to 20 min significantly increased the metal removal efficiency (MRE) of modified particles, whereas further increasing the plasma treatment time reduced the MRE due to the influence of an ablation mechanism. The developed particulate surfaces were capable of removing more than 96.7% of both Cu and Zn ions in 1 h. The combination of plasma polymerization and oxidative plasma treatment is an effective method for the fabrication of new adsorbents for the removal of heavy metals.

  15. Langevin formulation of quantum dynamics

    International Nuclear Information System (INIS)

    Roncadelli, M.

    1989-03-01

    We first show that nonrelativistic quantum mechanics formulated at imaginary-(h/2 π) can formally be viewed as the Fokker-Planck description of a frictionless brownian motion, which occurs (in general) in an absorbing medium. We next offer a new formulation of quantum mechanics, which is basically the Langevin treatment of this brownian motion. Explicitly, we derive a noise-average representation for the transition probability W(X'',t''|X',t'), in terms of the solutions to a Langevin equation with a Gaussian white-noise. Upon analytic continuation back to real-(h/2 π),W(X'',t''|X',t') becomes the propagator of the original Schroedinger equation. Our approach allows for a straightforward application to quantum dynamical problems of the mathematical techniques of classical stochastic processes. Moreover, computer simulations of quantum mechanical systems can be carried out by using numerical programs based on the Langevin dynamics. (author). 19 refs, 1 tab

  16. FY 1999 results of the regional consortium R and D project/the regional consortium energy R and D. 1st year. Development of the energy-saving type production technology of high-purity/transparent silica glass; 1999 nendo kojundo tomei sekiei glass no sho energy gata seizo gijutsu no kaihatsu seika hokokusho. 1

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    For the purpose of achieving the remarkable energy conservation, high accuracy and low cost in the production of high-purity/transparent silica glass, the developmental research was conducted on slip casting method. In the development of technology to synthesize silica powder by the sol-gel method, monodisperse - polydisperse high-purity colloidal silica was obtained. In the development of technology to make silica power ultra-highly pure, a process was found out in which silica particles can be obtained by applying moderate amounts of ammonium bicarbonate and aqueous ammonia to the solution of silicic acid for heating. In the slip cast forming, a high-density forming body with a mean particle size of 1.5{mu}m was obtained. In the trial manufacture of reflector model, a translucent silica glass sintered body was obtained by transcribing the gypsum type dimensional shape in high purity. Besides, experimental researches were conducted on the examination of gypsum type/resin type and evaluation of physical properties, heat deterioration characteristics of the actual multi-layer film and trial manufacture of the heat resistant film, analysis/evaluation of trace impurities inside silica glass, conditions for the manufacture of dense silica glass sheets, etc. (NEDO)

  17. Optimization of chlorphenesin emulgel formulation

    OpenAIRE

    Mohamed, Magdy I.

    2004-01-01

    This study was conducted to develop an emulgel formulation of chlorphenesin (CHL) using 2 types of gelling agents: hydroxypropylmethyl cellulose (HPMC) and Carbopol 934. The influence of the type of the gelling agent and the concentration of both the oil phase and emulsifying agent on the drug release from the prepared emulgels was investigated using a 23 factorial design. The prepared emulgels were evaluated for their physical appearance, rheological behavior, drug release, antifungal activi...

  18. Two-Stage Crystallizer Design for High Loading of Poorly Water-Soluble Pharmaceuticals in Porous Silica Matrices

    Directory of Open Access Journals (Sweden)

    Leia Dwyer

    2017-05-01

    Full Text Available While porous silica supports have been previously studied as carriers for nanocrystalline forms of poorly water-soluble active pharmaceutical ingredients (APIs, increasing the loading of API in these matrices is of great importance if these carriers are to be used in drug formulations. A dual-stage mixed-suspension, mixed-product removal (MSMPR crystallizer was designed in which the poorly soluble API fenofibrate was loaded into the porous matrices of pore sizes 35 nm–300 nm in the first stage, and then fed to a second stage in which the crystals were further grown in the pores. This resulted in high loadings of over 50 wt % while still producing nanocrystals confined to the pores without the formation of bulk-sized crystals on the surface of the porous silica. The principle was extended to another highly insoluble API, griseofulvin, to improve its loading in porous silica in a benchtop procedure. This work demonstrates a multi-step crystallization principle API in porous silica matrices with loadings high enough to produce final dosage forms of these poorly water-soluble APIs.

  19. Production and Application of Olivine Nano-Silica in Concrete

    Science.gov (United States)

    Mardiana, Oesman; Haryadi

    2017-05-01

    The aim of this research was to produce nano silica by synthesis of nano silica through extraction and dissolution of ground olivine rock, and applied the nano silica in the design concrete mix. The producing process of amorphous silica used sulfuric acid as the dissolution reagent. The separation of ground olivine rock occurred when the rock was heated in a batch reactor containing sulfuric acid. The results showed that the optimum mole ratio of olivine- acid was 1: 8 wherein the weight ratio of the highest nano silica generated. The heating temperature and acid concentration influenced the mass of silica produced, that was at temperature of 90 °C and 3 M acid giving the highest yield of 44.90%. Characterization using Fourier Transform Infrared (FTIR ) concluded that amorphous silica at a wavenumber of 1089 cm-1 indicated the presence of siloxane, Si-O-Si, stretching bond. Characterization using Scanning Electron Microscope - Energy Dispersive Spectroscopy (SEM-EDS) showed the surface and the size of the silica particles. The average size of silica particles was between 1-10 μm due to the rapid aggregation of the growing particles of nano silica into microparticles, caused of the pH control was not fully achieved.

  20. Arachidonic acid metabolism in silica-stimulated bovine alveolar macrophages

    International Nuclear Information System (INIS)

    Englen, M.D.

    1989-01-01

    The in vitro production of arachidonic acid (AA) metabolites in adherent bovine alveolar macrophages (BAM) incubated with silica was investigated. BAM were pre-labelled with 3 H-AA, and lipid metabolites released into the culture medium were analyzed by high performance liquid chromatography (HPLC). Lactate dehydrogenase (LDH) release was simultaneously assayed to provide an indication of cell injury. Increasing doses of silica selectively stimulated the 5-lipoxygenase pathway of AA metabolism, while cyclooxygenase metabolite output was suppressed. LDH release increased in a linear, dose-dependent fashion over the range of silica doses used. Moreover, within 15 min following addition of a high silica dose, a shift to the production of 5-lipoxygenase metabolites occurred, accompanied by a reduction in cyclooxygenase products. This rapid alteration in AA metabolism preceded cell injury. To examine the relationship between cytotoxicity and AA metabolite release by BAM exposed to silicas with different cytotoxic and fibrogenic activities, BAM were exposed to different doses of DQ-12, Minusil-5, and Sigma silicas, and carbonyl iron beads. The median effective dose (ED 50 ) of each particulate to stimulate the release of AA metabolites and LDH was calculated. The ED 50 values for DQ-12, Minusil-5, and Sigma silica showed that the relative cytotoxicities of the different silicas for BAM corresponded to the relative potencies of the silicas to elicit 5-lipoxygenase metabolites from BAM. These results indicate that the cytotoxic, and presumed fibrogenic potential, of a silica is correlated with the potency to stimulate the release of leukotrienes from AM

  1. Silica sol as grouting material: a physio-chemical analysis.

    Science.gov (United States)

    Sögaard, Christian; Funehag, Johan; Abbas, Zareen

    2018-01-01

    At present there is a pressing need to find an environmentally friendly grouting material for the construction of tunnels. Silica nanoparticles hold great potential of replacing the organic molecule based grouting materials currently used for this purpose. Chemically, silica nanoparticles are similar to natural silicates which are essential components of rocks and soil. Moreover, suspensions of silica nanoparticles of different sizes and desired reactivity are commercially available. However, the use of silica nanoparticles as grouting material is at an early stage of its technological development. There are some critical parameters such as long term stability and functionality of grouted silica that need to be investigated in detail before silica nanoparticles can be considered as a reliable grouting material. In this review article we present the state of the art regarding the chemical properties of silica nanoparticles commercially available, as well as experience gained from the use of silica as grouting material. We give a detailed description of the mechanisms underlying the gelling of silica by different salt solutions such as NaCl and KCl and how factors such as particle size, pH, and temperature affect the gelling and gel strength development. Our focus in this review is on linking the chemical properties of silica nanoparticles to the mechanical properties to better understand their functionality and stability as grouting material. Along the way we point out areas which need further research.

  2. Enhanced adsorption of trivalent arsenic from water by functionalized diatom silica shells.

    Directory of Open Access Journals (Sweden)

    Jianying Zhang

    Full Text Available The potential of porous diatom silica shells as a naturally abundant low-cost sorbent for the removal of arsenic in aqueous solutions was investigated in a batch study. The objective of this work was to chemically modify the silica shells of a diatom Melosira sp. with bifunctional (thiol and amino groups to effectively remove arsenic in its toxic As(III form (arsenite predominant in the aquatic environment. Sorption experiments with this novel sorbent were conducted under varying conditions of pH, time, dosage, and As(III concentration. A maximum adsorption capacity of 10.99 mg g-1 was achieved within 26 h for a solution containing 12 mg L-1 As(III at pH 4 and sorbent dosage of 2 g L-1. The functionalized diatom silica shells had a surface morphological change which was accompanied by increased pore size at the expense of reduced specific surface area and total pore volume. As(III adsorption was best fitted with the Langmuir-Freundlich model, and the adsorption kinetic data using pore surface diffusion model showed that both the external (film and internal (intraparticle diffusion can be rate-determining for As(III adsorption. Fourier transform infrared spectroscopy (FTIR indicated that the thiol and amino groups potentially responsible for As(III adsorption were grafted on the surface of diatom silica shells. X-ray photoelectron spectroscopy (XPS further verified that this unique sorbent proceeded via a chemisorption mechanism through the exchange between oxygen-containing groups of neutral As(III and thiol groups, and through the surface complexation between As(III and protonated nitrogen and hydroxyl groups. Results indicate that this functionalized bioadsorbent with a high As(III adsorption capacity holds promise for the treatment of As(III containing wastewater.

  3. Particulate silica test agents for hepa filters

    International Nuclear Information System (INIS)

    Bauman, A.J.

    1987-01-01

    The authors developed a solid test aerosol (Dri-Test) and a versatile portable delivery system for it. The aerosol is based on thermal silica, modified chemically to make it surface-hydrophobic and fluorescent under UV illumination. The fluorescent tag enables one to identify tested filters. Primary particles are 7 nm in diameter, spherical, and of density 2.20 gm-cm/sup -3/ bulk aerosol powder has a density of 0.048 gm-cm/sup -3/. Tests by means of laser particle counters, TSI Nucleation counters and California Measurements Quartz Microbalance mass analyzer show that the delivered aerosol has a bimodal size distribution with peaks near 80 and 100 nm. An estimated 40-50% of the aerosol has a size below the limits of detectability by laser (Las-X) counters, i.e. 50 nm. The surfachydrophobic aerosol is unaffected by ambient humidity and unlike hydrophilic silicas is innocuous to health

  4. Mechanical losses in thin fused silica fibres

    International Nuclear Information System (INIS)

    Bilenko, I A; Braginsky, V B; Lourie, S L

    2004-01-01

    Intracavity topology of the readout system for LIGO III project and table-top QND mechanical measurements under development require the use of small probe masses and suspensions with a very low level of internal losses. A good choice is to use thin fused silica fibres similar to LIGO II mirrors suspensions. Mechanical losses of silica fibres are investigated in this work through the study of quality factor dependence on diameter for pendulum and violin modes of oscillations with diameters ranging from 1.5 to 40 μm. The estimated values of effective mechanical loss angle show noticeably greater growth with lower diameters than might be expected while extrapolating known results of research done for thicker fibres

  5. Mechanical losses in thin fused silica fibres

    Energy Technology Data Exchange (ETDEWEB)

    Bilenko, I A; Braginsky, V B; Lourie, S L [Department of Oscillatory Physics, Physics Faculty, Moscow State University (Russian Federation)

    2004-03-07

    Intracavity topology of the readout system for LIGO III project and table-top QND mechanical measurements under development require the use of small probe masses and suspensions with a very low level of internal losses. A good choice is to use thin fused silica fibres similar to LIGO II mirrors suspensions. Mechanical losses of silica fibres are investigated in this work through the study of quality factor dependence on diameter for pendulum and violin modes of oscillations with diameters ranging from 1.5 to 40 {mu}m. The estimated values of effective mechanical loss angle show noticeably greater growth with lower diameters than might be expected while extrapolating known results of research done for thicker fibres.

  6. Densification of silica glass at ambient pressure

    International Nuclear Information System (INIS)

    Zheng Lianqing; An Qi; Fu Rongshan; Ni Sidao; Luo, S.-N.

    2006-01-01

    We show that densification of silica glass at ambient pressure as observed in irradiation experiments can be attributed to defect generation and subsequent structure relaxation. In our molecular dynamics simulations, defects are created by randomly removing atoms, by displacing atoms from their nominal positions in an otherwise intact glass, and by assigning certain atom excess kinetic energy (simulated ion implantation). The former forms vacancies; displacing atoms and ion implantation produce both vacancies and 'interstitials'. Appreciable densification is induced by these defects after equilibration of the defective glasses. The structural and vibrational properties of the densified glasses are characterized, displaying resembling features regardless of the means of densification. These results indicate that relaxation of high free-energy defects into metastable amorphous structures enriched in atomic coordination serves as a common mechanism for densification of silica glass at ambient pressure

  7. Active and passive silica waveguide integration

    DEFF Research Database (Denmark)

    Hübner, Jörg; Guldberg-Kjær, Søren Andreas

    2001-01-01

    . The increasing complexity and functionality of optical networks prompts a demand for highly integrated optical circuits. On-board optical amplifiers, monolithically integrated with functionalities like switching or multiplexing/demultiplexing will allow flexible incorporation of optical integrated circuits...... in existing and future networks without affecting the power budget of the system. Silica on silicon technology offers a unique possibility to selectively dope sections of the integrated circuit with erbium where amplification is desired. Some techniques for active/passive integration are reviewed and a silica......Integrated optical amplifiers are currently regaining interest. Stand-alone single integrated amplifiers offer only limited advantage over current erbium doped fiber amplifiers, whereas arrays of integrated amplifiers are very attractive due to miniaturization and the possibility of mass production...

  8. Silica removal in industrial effluents with high silica content and low hardness.

    Science.gov (United States)

    Latour, Isabel; Miranda, Ruben; Blanco, Angeles

    2014-01-01

    High silica content of de-inked paper mill effluents is limiting their regeneration and reuse after membrane treatments such as reverse osmosis (RO). Silica removal during softening processes is a common treatment; however, the effluent from the paper mill studied has a low hardness content, which makes the addition of magnesium compounds necessary to increase silica removal. Two soluble magnesium compounds (MgCl₂∙6H₂O and MgSO₄∙7H₂O) were tested at five dosages (250-1,500 mg/L) and different initial pH values. High removal rates (80-90%) were obtained with both products at the highest pH tested (11.5). With these removal efficiencies, it is possible to work at high RO recoveries (75-85%) without silica scaling. Although pH regulation significantly increased the conductivity of the waters (at pH 11.5 from 2.1 to 3.7-4.0 mS/cm), this could be partially solved by using Ca(OH)₂ instead of NaOH as pH regulator (final conductivity around 3.0 mS/cm). Maximum chemical oxygen demand (COD) removal obtained with caustic soda was lower than with lime (15 vs. 30%). Additionally, the combined use of a polyaluminum coagulant during the softening process was studied; the coagulant, however, did not significantly improve silica removal, obtaining a maximum increase of only 10%.

  9. Degradability and Clearance of Silicon, Organosilica, Silsesquioxane, Silica Mixed Oxide, and Mesoporous Silica Nanoparticles

    KAUST Repository

    Croissant, Jonas G.

    2017-01-13

    The biorelated degradability and clearance of siliceous nanomaterials have been questioned worldwide, since they are crucial prerequisites for the successful translation in clinics. Typically, the degradability and biocompatibility of mesoporous silica nanoparticles (MSNs) have been an ongoing discussion in research circles. The reason for such a concern is that approved pharmaceutical products must not accumulate in the human body, to prevent severe and unpredictable side-effects. Here, the biorelated degradability and clearance of silicon and silica nanoparticles (NPs) are comprehensively summarized. The influence of the size, morphology, surface area, pore size, and surface functional groups, to name a few, on the degradability of silicon and silica NPs is described. The noncovalent organic doping of silica and the covalent incorporation of either hydrolytically stable or redox- and enzymatically cleavable silsesquioxanes is then described for organosilica, bridged silsesquioxane (BS), and periodic mesoporous organosilica (PMO) NPs. Inorganically doped silica particles such as calcium-, iron-, manganese-, and zirconium-doped NPs, also have radically different hydrolytic stabilities. To conclude, the degradability and clearance timelines of various siliceous nanomaterials are compared and it is highlighted that researchers can select a specific nanomaterial in this large family according to the targeted applications and the required clearance kinetics.

  10. Cytotoxic effects in 3T3-L1 mouse and WI-38 human fibroblasts following 72 hour and 7 day exposures to commercial silica nanoparticles

    International Nuclear Information System (INIS)

    Stępnik, Maciej; Arkusz, Joanna; Smok-Pieniążek, Anna; Bratek-Skicki, Anna; Salvati, Anna; Lynch, Iseult; Dawson, Kenneth A.; Gromadzińska, Jolanta; De Jong, Wim H.; Rydzyński, Konrad

    2012-01-01

    The potential toxic effects in murine (3T3-L1) and human (WI-38) fibroblast cell lines of commercially available silica nanoparticles (NPs), Ludox CL (nominal size 21 nm) and CL-X (nominal size of 30 nm) were investigated with particular attention to the effect over long exposure times (the tests were run after 72 h exposure up to 7 days). These two formulations differed in physico-chemical properties and showed different stabilities in the cell culture medium used for the experiments. Ludox CL silica NPs were found to be cytotoxic only at the higher concentrations to the WI-38 cells (WST-1 and LDH assays) but not to the 3T3-L1 cells, whereas the Ludox CL-X silica NPs, which were less stable over the 72 h exposure, were cytotoxic to both cell lines in both assays. In the clonogenic assay both silica NPs induced a concentration dependent decrease in the surviving fraction of 3T3-L1 cells, with the Ludox CL-X silica NPs being more cytotoxic. Cell cycle analysis showed a trend indicating alterations in both cell lines at different phases with both silica NPs tested. Buthionine sulfoximine (γ-glutamylcysteine synthetase inhibitor) combined with Ludox CL-X was found to induce a strong decrease in 3T3-L1 cell viability which was not observed for the WI-38 cell line. This study clearly indicates that longer exposure studies may give important insights on the impact of nanomaterials on cells. However, and especially when investigating nanoparticle effects after such long exposure, it is fundamental to include a detailed physico-chemical characterization of the nanoparticles and their dispersions over the time scale of the experiment, in order to be able to interpret eventual impacts on cells. -- Highlights: ► Ludox CL silica NPs are cytotoxic to WI-38 fibroblasts but not to 3T3-L1 fibroblasts. ► Ludox CL-X silica NPs are cytotoxic to both cell lines. ► In clonogenic assay both silica NPs induce cytotoxicity, higher for CL-X silica. ► Cell cycle analysis shows

  11. Cracking in Drying Colloidal Films

    Science.gov (United States)

    Singh, Karnail B.; Tirumkudulu, Mahesh S.

    2007-05-01

    It has long been known that thick films of colloidal dispersions such as wet clays, paints, and coatings crack under drying. Although capillary stresses generated during drying have been recently identified as the cause for cracking, the existence of a maximum crack-free film thickness that depends on particle size, rigidity, and packing has not been understood. Here, we identify two distinct regimes for crack-free films based on the magnitude of compressive strain at the maximum attainable capillary pressure and show remarkable agreement of measurements with our theory. We anticipate our results to not only form the basis for design of coating formulations for the paints, coatings, and ceramics industry but also assist in the production of crack-free photonic band gap crystals.

  12. Mesoporous silica coatings for cephalosporin active release at the bone-implant interface

    Energy Technology Data Exchange (ETDEWEB)

    Rădulescu, Dragoş [Bucharest University Hospital, Department of Orthopedics and Traumatology, 169 Splaiul Independentei, 050098 Bucharest (Romania); Voicu, Georgeta; Oprea, Alexandra Elena; Andronescu, Ecaterina [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 1–7 Polizu Street, 011061 Bucharest (Romania); Grumezescu, Valentina [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 1–7 Polizu Street, 011061 Bucharest (Romania); Lasers Department, National Institute for Lasers, Plasma & Radiation Physics, PO Box MG-36, Măgurele, Bucharest (Romania); Holban, Alina Maria [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 1–7 Polizu Street, 011061 Bucharest (Romania); Department of Microbiology and Immunology, Faculty of Biology, University of Bucharest, 1-3 Portocalelor Lane, Bucharest (Romania); Research Institute of the University of Bucharest, Bd. Mihail Kogălniceanu 36-46, 050107 Bucharest (Romania); Vasile, Bogdan Stefan; Surdu, Adrian Vasile [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 1–7 Polizu Street, 011061 Bucharest (Romania); Grumezescu, Alexandru Mihai, E-mail: grumezescu@yahoo.com [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Materials Science, University Politehnica of Bucharest, 1–7 Polizu Street, 011061 Bucharest (Romania); and others

    2016-06-30

    Graphical abstract: - Highlights: • Silica/Zinforo thin coatings by matrix assisted pulsed laser evaporation. • Anti-adherent coating on medical surfaces against E. coli. • Thin coatings show a great biocompatibility in vitro and in vivo. - Abstract: In this study, we investigated the potential of MAPLE-deposited coatings mesoporous silica nanoparticles (MSNs) to release Zinforo (ceftarolinum fosmil) in biologically active form. The MSNs were prepared by using a classic procedure with cetyltrimethylammonium bromide as sacrificial template and tetraethylorthosilicate as the monomer. The Brunauer–Emmett–Teller (BET) and transmission electron microscopy (TEM) analyses revealed network-forming granules with diameters under 100 nm and an average pore diameter of 2.33 nm. The deposited films were characterized by SEM, TEM, XRD and IR. Microbiological analyses performed on ceftaroline-loaded films demonstrated that the antibiotic was released in an active form, decreasing the microbial adherence rate and colonization of the surface. Moreover, the in vitro and in vivo assays proved the excellent biodistribution and biocompatibility of the prepared systems. Our results suggest that the obtained bioactive coatings possess a significant potential for the design of drug delivery systems and antibacterial medical-use surfaces, with great applications in bone implantology.

  13. Colorimetric-based detection of TNT explosives using functionalized silica nanoparticles.

    Science.gov (United States)

    Idros, Noorhayati; Ho, Man Yi; Pivnenko, Mike; Qasim, Malik M; Xu, Hua; Gu, Zhongze; Chu, Daping

    2015-06-03

    This proof-of-concept study proposes a novel sensing mechanism for selective and label-free detection of 2,4,6-trinitrotoluene (TNT). It is realized by surface chemistry functionalization of silica nanoparticles (NPs) with 3-aminopropyl-triethoxysilane (APTES). The primary amine anchored to the surface of the silica nanoparticles (SiO2-NH2) acts as a capturing probe for TNT target binding to form Meisenheimer amine-TNT complexes. A colorimetric change of the self-assembled (SAM) NP samples from the initial green of a SiO2-NH2 nanoparticle film towards red was observed after successful attachment of TNT, which was confirmed as a result of the increased separation between the nanoparticles. The shift in the peak wavelength of the reflected light normal to the film surface and the associated change of the peak width were measured, and a merit function taking into account their combined effect was proposed for the detection of TNT concentrations from 10-12 to 10-4 molar. The selectivity of our sensing approach is confirmed by using TNT-bound nanoparticles incubated in AptamerX, with 2,4-dinitrotoluene (DNT) and toluene used as control and baseline, respectively. Our results show the repeatable systematic color change with the TNT concentration and the possibility to develop a robust, easy-to-use, and low-cost TNT detection method for performing a sensitive, reliable, and semi-quantitative detection in a wide detection range.

  14. Laccase immobilized on methylene blue modified mesoporous silica MCM-41/PVA

    International Nuclear Information System (INIS)

    Xu Xinhua; Lu Ping; Zhou Yumei; Zhao Zhenzhen; Guo Meiqing

    2009-01-01

    The mesoporous silica sieve MCM-41 containing methylene blue (MB) provides a suitable immobilization of biomolecule matrix due to its uniform pore structure, high surface areas, good biocompatibility and nice conductivity. Based on this, a facilely fabricated amperometric biosensor by entrapping laccase into the MB modified MCM-41/PVA composite film has been developed. Laccase from Trametes versicolor is assembled on a composite film of MCM-41 containing MB/PVA modified Au electrode and the electrode is characterized with respect to transmission electron microscopy (TEM) and scanning electron microscopic (SEM), Cyclic voltammetry (CV), response time, detection limit, linear range and activity of laccase. The laccase modified electrode remains good redox behavior in pH 4.95 acetate buffer solution, at room temperature in present of 0.1 mM catechol. The response time (t 90% ) of the modified electrode is less than 4 s for catechol. The detection limit is 0.331 μM and the linear detect range is about from 4.0 μM to 87.98 μM for catechol with a correlation coefficient of 0.99913(S/N = 3). The apparent Michaelis-Menten (K M app ) is estimated using the Lineweaver-Burk equation and the K M app value is about 0.256 mM. This work demonstrated that the mesoporous silica MCM-41 containing MB provides a novel support for laccase immobilization and the construction of biosensors with a faster response and better bioactivity.

  15. Coaxial carbon plasma gun deposition of amorphous carbon films

    Science.gov (United States)

    Sater, D. M.; Gulino, D. A.; Rutledge, S. K.

    1984-01-01

    A unique plasma gun employing coaxial carbon electrodes was used in an attempt to deposit thin films of amorphous diamond-like carbon. A number of different structural, compositional, and electrical characterization techniques were used to characterize these films. These included scanning electron microscopy, scanning transmission electron microscopy, X ray diffraction and absorption, spectrographic analysis, energy dispersive spectroscopy, and selected area electron diffraction. Optical absorption and electrical resistivity measurements were also performed. The films were determined to be primarily amorphous, with poor adhesion to fused silica substrates. Many inclusions of particulates were found to be present as well. Analysis of these particulates revealed the presence of trace impurities, such as Fe and Cu, which were also found in the graphite electrode material. The electrodes were the source of these impurities. No evidence of diamond-like crystallite structure was found in any of the film samples. Details of the apparatus, experimental procedure, and film characteristics are presented.

  16. Coaxial carbon plasma gun deposition of amorphous carbon films

    International Nuclear Information System (INIS)

    Sater, D.M.; Gulino, D.A.

    1984-03-01

    A unique plasma gun employing coaxial carbon electrodes was used in an attempt to deposit thin films of amorphous diamond-like carbon. A number of different structural, compositional, and electrical characterization techniques were used to characterize these films. These included scanning electron microscopy, scanning transmission electron microscopy, X ray diffraction and absorption, spectrographic analysis, energy dispersive spectroscopy, and selected area electron diffraction. Optical absorption and electrical resistivity measurements were also performed. The films were determined to be primarily amorphous, with poor adhesion to fused silica substrates. Many inclusions of particulates were found to be present as well. Analysis of these particulates revealed the presence of trace impurities, such as Fe and Cu, which were also found in the graphite electrode material. The electrodes were the source of these impurities. No evidence of diamond-like crystallite structure was found in any of the film samples. Details of the apparatus, experimental procedure, and film characteristics are presented

  17. A flexible, bolaamphiphilic template for mesoporous silicas.

    Science.gov (United States)

    Yuen, Alexander K L; Heinroth, Falk; Ward, Antony J; Masters, Anthony F; Maschmeyer, Thomas

    2013-08-28

    A novel symmetrical bolaamphiphile, containing two N-methylimidazolium head-groups bridged by a 32-methylene linker, was synthesized and characterized. A variety of mesoporous silicas was prepared using the bolaamphiphile as a "soft template". The effects of absolute surfactant concentration and synthesis conditions upon the morphologies of these silicas were investigated. For a given surfactant concentration, particle morphology; pore size; and pore ordering were modified through control of the template to silica-precursor ratio and synthesis conditions. Observed morphologies included: lenticular core-shell nanoparticles and decorticated globules, truncated hexagonal plates, and sheets. In all cases the mesopores are aligned along the shortest axis of the nanomaterial. Decorticated materials displayed surface areas of up to 1200 m(2) g(-1) and pore diameters (D(BJH)) of 24-28 Å. Small-angle X-ray diffraction and transmission electron microscopy measurements revealed that the majority of the materials has elliptical pores arranged in rectangular lattices (c2mm). Adoption of this symmetry group is a result of the template aggregate deformation from a regular hexagonal phase of cylindrical rods to a ribbon phase under the synthetic conditions.

  18. Novel silica-based ion exchange resin

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-11-01

    Eichrom`s highly successful Diphonixo resin resembles a conventional ion exchange resin in its use of sulfonic acid ligands on a styrene- divinylbenzene matrix. Diphonix resin exhibits rapid exchange kinetics that allow economical operation of ion exchange systems. Unlike conventional resins, Diphonix resin contains chelating ligands that are diphosphonic acid groups that recognize and remove the targeted metals and reject the more common elements such as sodium, calcium and magnesium. This latter property makes Diphonix ideal for many industrial scale applications, including those involving waste treatment. For treatment of low-level, transuranic (TRU) and high- level radioactive wastes, Diphonix`s polystyrene backbone hinders its application due to radiolytic stability of the carbon-hydrogen bonds and lack of compatibility with expected vitrification schemes. Polystyrene-based Diphonix is approximately 60% carbon- hydrogen. In response to an identified need within the Department of Energy for a resin with the positive attributes of Diphonix that also exhibits greater radiolytic stability and final waste form compatibility, Eichrom has successfully developed a new, silica-based resin version of Diphonix. Target application for this new resin is for use in environmental restoration and waste management situations involving the processing of low-level, transuranic and high-level radioactive wastes. The resin can also be used for processing liquid mixed waste (waste that contains low level radioactivity and hazardous constituents) including mixed wastes contaminated with organic compounds. Silica-based Diphonix is only 10% carbon-hydrogen, with the bulk of the matrix silica.

  19. Elastic Moduli of Permanently Densified Silica Glasses

    Science.gov (United States)

    Deschamps, T.; Margueritat, J.; Martinet, C.; Mermet, A.; Champagnon, B.

    2014-01-01

    Modelling the mechanical response of silica glass is still challenging, due to the lack of knowledge concerning the elastic properties of intermediate states of densification. An extensive Brillouin Light Scattering study on permanently densified silica glasses after cold compression in diamond anvil cell has been carried out, in order to deduce the elastic properties of such glasses and to provide new insights concerning the densification process. From sound velocity measurements, we derive phenomenological laws linking the elastic moduli of silica glass as a function of its densification ratio. The found elastic moduli are in excellent agreement with the sparse data extracted from literature, and we show that they do not depend on the thermodynamic path taken during densification (room temperature or heating). We also demonstrate that the longitudinal sound velocity exhibits an anomalous behavior, displaying a minimum for a densification ratio of 5%, and highlight the fact that this anomaly has to be distinguished from the compressibility anomaly of a-SiO2 in the elastic domain. PMID:25431218

  20. Structural and optical studies of nano-structure silica gel doped with different rare earth elements, prepared by two different sol -gel techniques

    International Nuclear Information System (INIS)

    Battisha, I.K.; El Beyally, A.; Seliman, S.I.; El Nahrawi, A.S.

    2005-01-01

    Structural and optical characteristics of pure silica gel (silica-xerogel, SiO 2 ) and doped with different concentrations ranging from 1 up to 6% of some rare earth (REEs) ions such as, praseodymium Pr +3 ,and Europium Eu +3 , Erbium Er +3 and Holmium Ho +3 , ions, in the form of thin film and monolith materials were prepared by sol - gel technique, Using tetra-ethoxysilane as precursor materials, which are of particular interest for sol-gel integrated optics applications. Some structural and optical features of sol-gel derived monolith and thin films are analyzed and compared, namely the structure of nano-particle monolith and thin film silica-gel samples, based on X-ray diffraction (XRD). The types of structural information obtainable are compared in detail. It is show that the XRD spectra of a-cristobalite are obtained for the two type materials and even by doping with the four REEs ions. Optical measurements of monolith and thin films were also studied and compared, the normal transmission and specular reflection were measured. The refractive index were calculated and discussed